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Series capacitors are used in electric transmission lines to increase their power transfer capacity. They compensate for the inductive reactance of the line. They offer a useful alternative to building new lines, in view of economic and environmental constraints. However, during transmission line faults, the presence of series capacitors causes problems for distance protection relays. Distance protection is the most widely used protection method in transmission lines, due to its relatively simple working principle and its ability to work with only local measurements of voltage and current. As the number of series compensated transmission lines is increasing, and the typical compensation level is also increasing, it has become essential to investigate protection methods that can be employed in place of traditional distance protection in series compensated lines. This thesis addresses the problems associated with line protection in the presence of series capacitor compensation. The first part is an assessment of the performance of traditional distance relays in cases with high levels of series compensation. This was based both on simulation studies and on published works describing research studies and industry experience with series capacitor projects and the related line-protection issues. It is concluded that traditional distance protection cannot be used reliably with high levels of series compensation. The second part of the thesis describes some alternative protection methods that are developed and studied as candidates for better single-ended protection of series-compensated lines. These are based on incremental quantities, Lissajous curves and RL/RLC line models. These methods show positive results for single ended protection of series compensated lines.The incremental-quantity based method is fast and operates reliably, but faces under-reach problems with fault resistance. The Lissajous-curve basedmethod can be used as an alternative to the Fourier transform, Seriekondensatorer används i elektriska transmissionsledningar för att öka deras kraftöoverföringskapacitet. De kompenserar för ledningens induktiv reaktans. På grund av ekonomiska och miljömässiga begränsningar erbjuder de en användbar alternativ till att bygga nya ledningar. Vid fel i ledningenkan dock seriekondensatorer orsakar problem för distansskyddsreläer. Distansskydd är den mest använda skyddsmetoden hos transmissionsledningar, som konsekvens av sitt relativt enkelt arbetsprincip och av att endast lokala mätningar av spännings och ström behövs. Då det finns ökningar i antalet seriekompenserad transmissionsledningar samt deras kompensationsnivåer, har det blivit väsentligt att utreda skyddsmetoder som kan användas i stället för traditionellt distansskydd. Denna avhandling tar upp problematiken av reläskydd hos seriekompenseradeledningar. Den första delen är en bedömning av prestationen av traditionella distansskyddsreläer vid fall med höga seriekompenseringsnivåer. Detta baserades både på simuleringsstudier och på publicerade arbeten som beskriverforskningsstudier och branscherfarenhet av skydd hos seriekompenseradeledningar. Man drar slutsatsen att traditionellt distansskydd inte kan användas på ett tillförlitligt sätt med höga seriekompenseringsnivåer. Den andra delen av avhandlingen beskriver några alternativa skyddsmetoder som utvecklas och studeras som kandidater för bättre skydd av seriekompenserade ledningar. Dessa är baserade på inkrementella storheter, Lissajous-kurvor och RL/RLC ledningsmodeller. Dessa metoder visar positiva resultat för kommunikationsoberoende skydd av seriekompenserade linjer. Metoden baserad på inkrementella storheter är snabb och fungerar tillförlitligt, men den har problem med underräckning vid högre felmotstånd. Den Lissajous-kurvabaseradmetoden kan användas som ett alternativ till fourier transform och har vissa fördelar för att övervinna inversionssituationer, men den kräver minst en periodav data. Den RL- och RLC-modellbas, QC 20230210

Series capacitors are used in electric transmission lines to increase their power transfer capacity. They compensate for the inductive reactance of the line. They offer a useful alternative to building new lines, in view of economic and environmental constraints. However, during transmission line faults, the presence of series capacitors causes problems for distance protection relays. Distance protection is the most widely used protection method in transmission lines, due to its relatively simple working principle and its ability to work with only local measurements of voltage and current. As the number of series compensated transmission lines is increasing, and the typical compensation level is also increasing, it has become essential to investigate protection methods that can be employed in place of traditional distance protection in series compensated lines. This thesis addresses the problems associated with line protection in the presence of series capacitor compensation. The first part is an assessment of the performance of traditional distance relays in cases with high levels of series compensation. This was based both on simulation studies and on published works describing research studies and industry experience with series capacitor projects and the related line-protection issues. It is concluded that traditional distance protection cannot be used reliably with high levels of series compensation. The second part of the thesis describes some alternative protection methods that are developed and studied as candidates for better single-ended protection of series-compensated lines. These are based on incremental quantities, Lissajous curves and RL/RLC line models. These methods show positive results for single ended protection of series compensated lines.The incremental-quantity based method is fast and operates reliably, but faces under-reach problems with fault resistance. The Lissajous-curve basedmethod can be used as an alternative to the Fourier transform, Seriekondensatorer används i elektriska transmissionsledningar för att öka deras kraftöoverföringskapacitet. De kompenserar för ledningens induktiv reaktans. På grund av ekonomiska och miljömässiga begränsningar erbjuder de en användbar alternativ till att bygga nya ledningar. Vid fel i ledningenkan dock seriekondensatorer orsakar problem för distansskyddsreläer. Distansskydd är den mest använda skyddsmetoden hos transmissionsledningar, som konsekvens av sitt relativt enkelt arbetsprincip och av att endast lokala mätningar av spännings och ström behövs. Då det finns ökningar i antalet seriekompenserad transmissionsledningar samt deras kompensationsnivåer, har det blivit väsentligt att utreda skyddsmetoder som kan användas i stället för traditionellt distansskydd. Denna avhandling tar upp problematiken av reläskydd hos seriekompenseradeledningar. Den första delen är en bedömning av prestationen av traditionella distansskyddsreläer vid fall med höga seriekompenseringsnivåer. Detta baserades både på simuleringsstudier och på publicerade arbeten som beskriverforskningsstudier och branscherfarenhet av skydd hos seriekompenseradeledningar. Man drar slutsatsen att traditionellt distansskydd inte kan användas på ett tillförlitligt sätt med höga seriekompenseringsnivåer. Den andra delen av avhandlingen beskriver några alternativa skyddsmetoder som utvecklas och studeras som kandidater för bättre skydd av seriekompenserade ledningar. Dessa är baserade på inkrementella storheter, Lissajous-kurvor och RL/RLC ledningsmodeller. Dessa metoder visar positiva resultat för kommunikationsoberoende skydd av seriekompenserade linjer. Metoden baserad på inkrementella storheter är snabb och fungerar tillförlitligt, men den har problem med underräckning vid högre felmotstånd. Den Lissajous-kurvabaseradmetoden kan användas som ett alternativ till fourier transform och har vissa fördelar för att övervinna inversionssituationer, men den kräver minst en periodav data. Den RL- och RLC-modellbas, QC 20230210

Series capacitors are used in electric transmission lines to increase their power transfer capacity. They compensate for the inductive reactance of the line. They offer a useful alternative to building new lines, in view of economic and environmental constraints. However, during transmission line faults, the presence of series capacitors causes problems for distance protection relays. Distance protection is the most widely used protection method in transmission lines, due to its relatively simple working principle and its ability to work with only local measurements of voltage and current. As the number of series compensated transmission lines is increasing, and the typical compensation level is also increasing, it has become essential to investigate protection methods that can be employed in place of traditional distance protection in series compensated lines. This thesis addresses the problems associated with line protection in the presence of series capacitor compensation. The first part is an assessment of the performance of traditional distance relays in cases with high levels of series compensation. This was based both on simulation studies and on published works describing research studies and industry experience with series capacitor projects and the related line-protection issues. It is concluded that traditional distance protection cannot be used reliably with high levels of series compensation. The second part of the thesis describes some alternative protection methods that are developed and studied as candidates for better single-ended protection of series-compensated lines. These are based on incremental quantities, Lissajous curves and RL/RLC line models. These methods show positive results for single ended protection of series compensated lines.The incremental-quantity based method is fast and operates reliably, but faces under-reach problems with fault resistance. The Lissajous-curve basedmethod can be used as an alternative to the Fourier transform, Seriekondensatorer används i elektriska transmissionsledningar för att öka deras kraftöoverföringskapacitet. De kompenserar för ledningens induktiv reaktans. På grund av ekonomiska och miljömässiga begränsningar erbjuder de en användbar alternativ till att bygga nya ledningar. Vid fel i ledningenkan dock seriekondensatorer orsakar problem för distansskyddsreläer. Distansskydd är den mest använda skyddsmetoden hos transmissionsledningar, som konsekvens av sitt relativt enkelt arbetsprincip och av att endast lokala mätningar av spännings och ström behövs. Då det finns ökningar i antalet seriekompenserad transmissionsledningar samt deras kompensationsnivåer, har det blivit väsentligt att utreda skyddsmetoder som kan användas i stället för traditionellt distansskydd. Denna avhandling tar upp problematiken av reläskydd hos seriekompenseradeledningar. Den första delen är en bedömning av prestationen av traditionella distansskyddsreläer vid fall med höga seriekompenseringsnivåer. Detta baserades både på simuleringsstudier och på publicerade arbeten som beskriverforskningsstudier och branscherfarenhet av skydd hos seriekompenseradeledningar. Man drar slutsatsen att traditionellt distansskydd inte kan användas på ett tillförlitligt sätt med höga seriekompenseringsnivåer. Den andra delen av avhandlingen beskriver några alternativa skyddsmetoder som utvecklas och studeras som kandidater för bättre skydd av seriekompenserade ledningar. Dessa är baserade på inkrementella storheter, Lissajous-kurvor och RL/RLC ledningsmodeller. Dessa metoder visar positiva resultat för kommunikationsoberoende skydd av seriekompenserade linjer. Metoden baserad på inkrementella storheter är snabb och fungerar tillförlitligt, men den har problem med underräckning vid högre felmotstånd. Den Lissajous-kurvabaseradmetoden kan användas som ett alternativ till fourier transform och har vissa fördelar för att övervinna inversionssituationer, men den kräver minst en periodav data. Den RL- och RLC-modellbas, QC 20230210

Series capacitors are used in electric transmission lines to increase their power transfer capacity. They compensate for the inductive reactance of the line. They offer a useful alternative to building new lines, in view of economic and environmental constraints. However, during transmission line faults, the presence of series capacitors causes problems for distance protection relays. Distance protection is the most widely used protection method in transmission lines, due to its relatively simple working principle and its ability to work with only local measurements of voltage and current. As the number of series compensated transmission lines is increasing, and the typical compensation level is also increasing, it has become essential to investigate protection methods that can be employed in place of traditional distance protection in series compensated lines. This thesis addresses the problems associated with line protection in the presence of series capacitor compensation. The first part is an assessment of the performance of traditional distance relays in cases with high levels of series compensation. This was based both on simulation studies and on published works describing research studies and industry experience with series capacitor projects and the related line-protection issues. It is concluded that traditional distance protection cannot be used reliably with high levels of series compensation. The second part of the thesis describes some alternative protection methods that are developed and studied as candidates for better single-ended protection of series-compensated lines. These are based on incremental quantities, Lissajous curves and RL/RLC line models. These methods show positive results for single ended protection of series compensated lines.The incremental-quantity based method is fast and operates reliably, but faces under-reach problems with fault resistance. The Lissajous-curve basedmethod can be used as an alternative to the Fourier transform, Seriekondensatorer används i elektriska transmissionsledningar för att öka deras kraftöoverföringskapacitet. De kompenserar för ledningens induktiv reaktans. På grund av ekonomiska och miljömässiga begränsningar erbjuder de en användbar alternativ till att bygga nya ledningar. Vid fel i ledningenkan dock seriekondensatorer orsakar problem för distansskyddsreläer. Distansskydd är den mest använda skyddsmetoden hos transmissionsledningar, som konsekvens av sitt relativt enkelt arbetsprincip och av att endast lokala mätningar av spännings och ström behövs. Då det finns ökningar i antalet seriekompenserad transmissionsledningar samt deras kompensationsnivåer, har det blivit väsentligt att utreda skyddsmetoder som kan användas i stället för traditionellt distansskydd. Denna avhandling tar upp problematiken av reläskydd hos seriekompenseradeledningar. Den första delen är en bedömning av prestationen av traditionella distansskyddsreläer vid fall med höga seriekompenseringsnivåer. Detta baserades både på simuleringsstudier och på publicerade arbeten som beskriverforskningsstudier och branscherfarenhet av skydd hos seriekompenseradeledningar. Man drar slutsatsen att traditionellt distansskydd inte kan användas på ett tillförlitligt sätt med höga seriekompenseringsnivåer. Den andra delen av avhandlingen beskriver några alternativa skyddsmetoder som utvecklas och studeras som kandidater för bättre skydd av seriekompenserade ledningar. Dessa är baserade på inkrementella storheter, Lissajous-kurvor och RL/RLC ledningsmodeller. Dessa metoder visar positiva resultat för kommunikationsoberoende skydd av seriekompenserade linjer. Metoden baserad på inkrementella storheter är snabb och fungerar tillförlitligt, men den har problem med underräckning vid högre felmotstånd. Den Lissajous-kurvabaseradmetoden kan användas som ett alternativ till fourier transform och har vissa fördelar för att övervinna inversionssituationer, men den kräver minst en periodav data. Den RL- och RLC-modellbas, QC 20230210

Series capacitors are used in electric transmission lines to increase their power transfer capacity. They compensate for the inductive reactance of the line. They offer a useful alternative to building new lines, in view of economic and environmental constraints. However, during transmission line faults, the presence of series capacitors causes problems for distance protection relays. Distance protection is the most widely used protection method in transmission lines, due to its relatively simple working principle and its ability to work with only local measurements of voltage and current. As the number of series compensated transmission lines is increasing, and the typical compensation level is also increasing, it has become essential to investigate protection methods that can be employed in place of traditional distance protection in series compensated lines. This thesis addresses the problems associated with line protection in the presence of series capacitor compensation. The first part is an assessment of the performance of traditional distance relays in cases with high levels of series compensation. This was based both on simulation studies and on published works describing research studies and industry experience with series capacitor projects and the related line-protection issues. It is concluded that traditional distance protection cannot be used reliably with high levels of series compensation. The second part of the thesis describes some alternative protection methods that are developed and studied as candidates for better single-ended protection of series-compensated lines. These are based on incremental quantities, Lissajous curves and RL/RLC line models. These methods show positive results for single ended protection of series compensated lines.The incremental-quantity based method is fast and operates reliably, but faces under-reach problems with fault resistance. The Lissajous-curve basedmethod can be used as an alternative to the Fourier transform, Seriekondensatorer används i elektriska transmissionsledningar för att öka deras kraftöoverföringskapacitet. De kompenserar för ledningens induktiv reaktans. På grund av ekonomiska och miljömässiga begränsningar erbjuder de en användbar alternativ till att bygga nya ledningar. Vid fel i ledningenkan dock seriekondensatorer orsakar problem för distansskyddsreläer. Distansskydd är den mest använda skyddsmetoden hos transmissionsledningar, som konsekvens av sitt relativt enkelt arbetsprincip och av att endast lokala mätningar av spännings och ström behövs. Då det finns ökningar i antalet seriekompenserad transmissionsledningar samt deras kompensationsnivåer, har det blivit väsentligt att utreda skyddsmetoder som kan användas i stället för traditionellt distansskydd. Denna avhandling tar upp problematiken av reläskydd hos seriekompenseradeledningar. Den första delen är en bedömning av prestationen av traditionella distansskyddsreläer vid fall med höga seriekompenseringsnivåer. Detta baserades både på simuleringsstudier och på publicerade arbeten som beskriverforskningsstudier och branscherfarenhet av skydd hos seriekompenseradeledningar. Man drar slutsatsen att traditionellt distansskydd inte kan användas på ett tillförlitligt sätt med höga seriekompenseringsnivåer. Den andra delen av avhandlingen beskriver några alternativa skyddsmetoder som utvecklas och studeras som kandidater för bättre skydd av seriekompenserade ledningar. Dessa är baserade på inkrementella storheter, Lissajous-kurvor och RL/RLC ledningsmodeller. Dessa metoder visar positiva resultat för kommunikationsoberoende skydd av seriekompenserade linjer. Metoden baserad på inkrementella storheter är snabb och fungerar tillförlitligt, men den har problem med underräckning vid högre felmotstånd. Den Lissajous-kurvabaseradmetoden kan användas som ett alternativ till fourier transform och har vissa fördelar för att övervinna inversionssituationer, men den kräver minst en periodav data. Den RL- och RLC-modellbas, QC 20230210

Series capacitors are installed in transmission lines to increase power transfer capacity. However, their addition creates challenges for the line protection. Security and speed of phasor based protection schemes that work with local measurements (communication independent) are severely affected in the presence of series capacitors. Therefore, time-domain based protection methods may be considered as a potential solution for communication independent protection of series compensated lines. In this paper, an incremental quantity based protection scheme is presented for series compensated lines with the capacitor in the middle of the line. The method involves estimating the voltage across the capacitor bank, based on the current in the capacitor bank and metal oxide varistor during faults. Then this capacitor voltage estimation is used to implement the incremental quantity protection. The incremental quantity method consists of fault detection, phase selection, directional discrimination and distance estimation. A PSCAD model of a 500 kV, 200 km transmission line is used to simulate fault cases for evaluating the method. The proposed method is tested with different compensation levels, fault types, fault positions, inception angles, fault resistances and source impedance ratios. The results show that the proposed method can meet the dependability and security demands for the protection of series compensated lines., Part of ISBN [9781839537196]QC 20240706

Series capacitors are installed in transmission lines to increase power transfer capacity. However, their addition creates challenges for the line protection. Security and speed of phasor based protection schemes that work with local measurements (communication independent) are severely affected in the presence of series capacitors. Therefore, time-domain based protection methods may be considered as a potential solution for communication independent protection of series compensated lines. In this paper, an incremental quantity based protection scheme is presented for series compensated lines with the capacitor in the middle of the line. The method involves estimating the voltage across the capacitor bank, based on the current in the capacitor bank and metal oxide varistor during faults. Then this capacitor voltage estimation is used to implement the incremental quantity protection. The incremental quantity method consists of fault detection, phase selection, directional discrimination and distance estimation. A PSCAD model of a 500 kV, 200 km transmission line is used to simulate fault cases for evaluating the method. The proposed method is tested with different compensation levels, fault types, fault positions, inception angles, fault resistances and source impedance ratios. The results show that the proposed method can meet the dependability and security demands for the protection of series compensated lines., QC 20220509

Series capacitors are installed in transmission lines to increase power transfer capacity. However, their addition creates challenges for the line protection. Security and speed of phasor based protection schemes that work with local measurements (communication independent) are severely affected in the presence of series capacitors. Therefore, time-domain based protection methods may be considered as a potential solution for communication independent protection of series compensated lines. In this paper, an incremental quantity based protection scheme is presented for series compensated lines with the capacitor in the middle of the line. The method involves estimating the voltage across the capacitor bank, based on the current in the capacitor bank and metal oxide varistor during faults. Then this capacitor voltage estimation is used to implement the incremental quantity protection. The incremental quantity method consists of fault detection, phase selection, directional discrimination and distance estimation. A PSCAD model of a 500 kV, 200 km transmission line is used to simulate fault cases for evaluating the method. The proposed method is tested with different compensation levels, fault types, fault positions, inception angles, fault resistances and source impedance ratios. The results show that the proposed method can meet the dependability and security demands for the protection of series compensated lines., QC 20220509

Series capacitors are installed in transmission lines to increase power transfer capacity. However, their addition creates challenges for the line protection. Security and speed of phasor based protection schemes that work with local measurements (communication independent) are severely affected in the presence of series capacitors. Therefore, time-domain based protection methods may be considered as a potential solution for communication independent protection of series compensated lines. In this paper, an incremental quantity based protection scheme is presented for series compensated lines with the capacitor in the middle of the line. The method involves estimating the voltage across the capacitor bank, based on the current in the capacitor bank and metal oxide varistor during faults. Then this capacitor voltage estimation is used to implement the incremental quantity protection. The incremental quantity method consists of fault detection, phase selection, directional discrimination and distance estimation. A PSCAD model of a 500 kV, 200 km transmission line is used to simulate fault cases for evaluating the method. The proposed method is tested with different compensation levels, fault types, fault positions, inception angles, fault resistances and source impedance ratios. The results show that the proposed method can meet the dependability and security demands for the protection of series compensated lines., QC 20220509

Series capacitors are installed in transmission lines to increase power transfer capacity. However, their addition creates challenges for the line protection. Security and speed of phasor based protection schemes that work with local measurements (communication independent) are severely affected in the presence of series capacitors. Therefore, time-domain based protection methods may be considered as a potential solution for communication independent protection of series compensated lines. In this paper, an incremental quantity based protection scheme is presented for series compensated lines with the capacitor in the middle of the line. The method involves estimating the voltage across the capacitor bank, based on the current in the capacitor bank and metal oxide varistor during faults. Then this capacitor voltage estimation is used to implement the incremental quantity protection. The incremental quantity method consists of fault detection, phase selection, directional discrimination and distance estimation. A PSCAD model of a 500 kV, 200 km transmission line is used to simulate fault cases for evaluating the method. The proposed method is tested with different compensation levels, fault types, fault positions, inception angles, fault resistances and source impedance ratios. The results show that the proposed method can meet the dependability and security demands for the protection of series compensated lines., QC 20220509

Series capacitors are installed in transmission lines to increase power transfer capacity. However, their addition creates challenges for the line protection. Security and speed of phasor based protection schemes that work with local measurements (communication independent) are severely affected in the presence of series capacitors. Therefore, time-domain based protection methods may be considered as a potential solution for communication independent protection of series compensated lines. In this paper, an incremental quantity based protection scheme is presented for series compensated lines with the capacitor in the middle of the line. The method involves estimating the voltage across the capacitor bank, based on the current in the capacitor bank and metal oxide varistor during faults. Then this capacitor voltage estimation is used to implement the incremental quantity protection. The incremental quantity method consists of fault detection, phase selection, directional discrimination and distance estimation. A PSCAD model of a 500 kV, 200 km transmission line is used to simulate fault cases for evaluating the method. The proposed method is tested with different compensation levels, fault types, fault positions, inception angles, fault resistances and source impedance ratios. The results show that the proposed method can meet the dependability and security demands for the protection of series compensated lines., QC 20220509

Introduction of series capacitors in transmission lines can cause problems with reliability and security of distance protection, due to problems such as current inversion, voltage inversion and sub-synchronous oscillation. Distance protection is widely used for transmission lines and has desirable features not available from traditional alternatives, which has motivated attempts to adapt it to work better with series capacitors. Research and development in overcoming the challenges using distance protection in series compensated lines have also been actively pursued during this period. Thus there is a need to summarize and systematically categorize developments, to show recent trends and highlight further research opportunities. This paper aims to fill that gap by a thorough literature survey of distance protection of series compensated lines, including a clear background of the problems that need to be solved. The scope of this work is limited to distance protection schemes that work with local measurements only. It is observed that the developments in this domain are largely concentrated on voltage drop estimation across capacitor bank, phasor estimation and adaptive protection schemes. This work will provide an overview of the latest developments for experienced researchers and will be a reference for new researchers interested in this domain., QC 20200923

This paper reviews the basics of series compensation in transmission systems through a literature survey. The benefits that this technology brings to enhance the steady state and dynamic operation of power systems are analyzed. The review outlines the evolution of the series compensation technologies, from mechanically operated switches to line- and self-commutated power electronic devices, covering control issues, different applications, practical realizations, and case studies. Finally, the paper closes with the major challenges that this technology will face in the near future to achieve a fully decarbonized power system.

In this paper a series controller from the FACTS (Flexible AC transmission system) family named as 'Thyristor Controlled Series Capacitor' (TCSC) is designed using Microcontroller. A transmission lines operating at high voltages is required to transmit power from generating station to load. The laboratory setup of circuit using a Thyristor controlled reactor in series with a capacitor will discussed in this paper. This paper also presents experimental results of a TCSC connected to a single phase system. This paper investigates the effects of TCSC on transmission line to improve voltage stability. The stability of system has been determined by using V-I and P-V curves.

In this paper a series controller from the FACTS (Flexible AC transmission system) family named as 'Thyristor Controlled Series Capacitor' (TCSC) is designed using Microcontroller. A transmission lines operating at high voltages is required to transmit power from generating station to load. The laboratory setup of circuit using a Thyristor controlled reactor in series with a capacitor will discussed in this paper. This paper also presents experimental results of a TCSC connected to a single phase system. This paper investigates the effects of TCSC on transmission line to improve voltage stability. The stability of system has been determined by using V-I and P-V curves.

In this paper a series controller from the FACTS (Flexible AC transmission system) family named as 'Thyristor Controlled Series Capacitor' (TCSC) is designed using Microcontroller. A transmission lines operating at high voltages is required to transmit power from generating station to load. The laboratory setup of circuit using a Thyristor controlled reactor in series with a capacitor will discussed in this paper. This paper also presents experimental results of a TCSC connected to a single phase system. This paper investigates the effects of TCSC on transmission line to improve voltage stability. The stability of system has been determined by using V-I and P-V curves.

In this paper a series controller from the FACTS (Flexible AC transmission system) family named as 'Thyristor Controlled Series Capacitor' (TCSC) is designed using Microcontroller. A transmission lines operating at high voltages is required to transmit power from generating station to load. The laboratory setup of circuit using a Thyristor controlled reactor in series with a capacitor will discussed in this paper. This paper also presents experimental results of a TCSC connected to a single phase system. This paper investigates the effects of TCSC on transmission line to improve voltage stability. The stability of system has been determined by using V-I and P-V curves.

In this paper a series controller from the FACTS (Flexible AC transmission system) family named as 'Thyristor Controlled Series Capacitor' (TCSC) is designed using Microcontroller. A transmission lines operating at high voltages is required to transmit power from generating station to load. The laboratory setup of circuit using a Thyristor controlled reactor in series with a capacitor will discussed in this paper. This paper also presents experimental results of a TCSC connected to a single phase system. This paper investigates the effects of TCSC on transmission line to improve voltage stability. The stability of system has been determined by using V-I and P-V curves.

In this paper a series controller from the FACTS (Flexible AC transmission system) family named as 'Thyristor Controlled Series Capacitor' (TCSC) is designed using Microcontroller. A transmission lines operating at high voltages is required to transmit power from generating station to load. The laboratory setup of circuit using a Thyristor controlled reactor in series with a capacitor will discussed in this paper. This paper also presents experimental results of a TCSC connected to a single phase system. This paper investigates the effects of TCSC on transmission line to improve voltage stability. The stability of system has been determined by using V-I and P-V curves.

This paper reviews the basics of series compensation in transmission systems through a literature survey. The benefits that this technology brings to enhance the steady state and dynamic operation of power systems are analyzed. The review outlines the evolution of the series compensation technologies, from mechanically operated switches to line- and self-commutated power electronic devices, covering control issues, different applications, practical realizations, and case studies. Finally, the paper closes with the major challenges that this technology will face in the near future to achieve a fully decarbonized power system.

Replacing conventional generation by power electronics based generation changes the dynamic characteristics of the power system. This results among others in the increased susceptibility to sub synchronous oscillations (SSO). This paper proposes a systematic procedure for mitigating the interactions between a DFIG and a series compensated transmission line using the phase imbalance compensation (PIC) concept. The impact of the series and parallel PIC on the resonance behaviour of the grid is first thoroughly investigated. Then, the influence of the system strength on the capabilities of the PIC to mitigate DFIG-SSR is assessed. Based on the findings a design framework which enables the systematic assessment of the series and parallel PIC for mitigating DFIG-SSR is developed and successfully implemented in the IEEE 39 bus system. Comparison between both concepts reveals that the parallel PIC is better suited to mitigate DFIG-SSR. The impedance based stability analysis and detailed time domain electromagnetic transient (EMT) simulations are used to screen and validate the results., Intelligent Electrical Power Grids

Subsynchronous oscillations (SSO) were an issue that occurred in the past with conventional generators and were studied extensively throughout the years. However, with the rise of inverter-based resources, a new form of SSO emerged under the name subsynchronous control interaction (SSCI). More specifically, a resonance case occurs between Type-3 wind turbines and series compensation that can damage equipment within the wind farm and disrupt power generation. This work explores the types of SSCI and the various analysis methods as well as mitigation of SSCI. The work expands on the concept of frequency scan to be able to use it in an on-line setting with its output data used to mitigate SSCI through the modification of wind turbine parameters. Multiple frequency scans are conducted using PSCAD/EMTDC software to build a lookup table and harmonic injection is used in a parallel configuration to obtain the impedance of the system. Once the impedance of the system is obtained then the value of the parameters is adjusted using the look-up table. Harmonic injection is optimized through phase shifts to ensure minimal disruption of the steady-state operating point and is conducted using Python programming language with PSCAD Automation Library. Simulation results demonstrate the effectiveness of this approach by ensuring oscillations do not grow exponentially in comparison to the regular operation of the wind farm.

Series capacitors increase the power transfer limit of transmission lines. However, the protection of series compensated lines using only local measurement is challenging. Phasor based distance protection experiences delay and directional problems in the presence of a series capacitor. This paper presents an incremental quantity based distance protection algorithm for series compensated lines. The algorithm uses instantaneous voltage and current measurement from the local bus. It consists of capacitor voltage estimation, fault detection, phase selection, directional discrimination and distance estimation. The algorithm is extensively tested based on simulations with a line-end series capacitor, considering different source impedance ratios, fault inception angle, compensation levels, and fault resistance, location and type. This time-domain method is shown to work well, with fast decision time., QC 20220112

This paper reviews the basics of series compensation in transmission systems through a literature survey. The benefits that this technology brings to enhance the steady state and dynamic operation of power systems are analyzed. The review outlines the evolution of the series compensation technologies, from mechanically operated switches to line- and self-commutated power electronic devices, covering control issues, different applications, practical realizations, and case studies. Finally, the paper closes with the major challenges that this technology will face in the near future to achieve a fully decarbonized power system.

In this paper a series controller from the FACTS (Flexible AC transmission system) family named as 'Thyristor Controlled Series Capacitor' (TCSC) is designed using Microcontroller. A transmission lines operating at high voltages is required to transmit power from generating station to load. The laboratory setup of circuit using a Thyristor controlled reactor in series with a capacitor will discussed in this paper. This paper also presents experimental results of a TCSC connected to a single phase system. This paper investigates the effects of TCSC on transmission line to improve voltage stability. The stability of system has been determined by using V-I and P-V curves.

Subsynchronous oscillations (SSO) were an issue that occurred in the past with conventional generators and were studied extensively throughout the years. However, with the rise of inverter-based resources, a new form of SSO emerged under the name subsynchronous control interaction (SSCI). More specifically, a resonance case occurs between Type-3 wind turbines and series compensation that can damage equipment within the wind farm and disrupt power generation. This work explores the types of SSCI and the various analysis methods as well as mitigation of SSCI. The work expands on the concept of frequency scan to be able to use it in an on-line setting with its output data used to mitigate SSCI through the modification of wind turbine parameters. Multiple frequency scans are conducted using PSCAD/EMTDC software to build a lookup table and harmonic injection is used in a parallel configuration to obtain the impedance of the system. Once the impedance of the system is obtained then the value of the parameters is adjusted using the look-up table. Harmonic injection is optimized through phase shifts to ensure minimal disruption of the steady-state operating point and is conducted using Python programming language with PSCAD Automation Library. Simulation results demonstrate the effectiveness of this approach by ensuring oscillations do not grow exponentially in comparison to the regular operation of the wind farm.

This paper reviews the basics of series compensation in transmission systems through a literature survey. The benefits that this technology brings to enhance the steady state and dynamic operation of power systems are analyzed. The review outlines the evolution of the series compensation technologies, from mechanically operated switches to line- and self-commutated power electronic devices, covering control issues, different applications, practical realizations, and case studies. Finally, the paper closes with the major challenges that this technology will face in the near future to achieve a fully decarbonized power system.

This paper reviews the basics of series compensation in transmission systems through a literature survey. The benefits that this technology brings to enhance the steady state and dynamic operation of power systems are analyzed. The review outlines the evolution of the series compensation technologies, from mechanically operated switches to line- and self-commutated power electronic devices, covering control issues, different applications, practical realizations, and case studies. Finally, the paper closes with the major challenges that this technology will face in the near future to achieve a fully decarbonized power system.

Replacing conventional generation by power electronics based generation changes the dynamic characteristics of the power system. This results among others in the increased susceptibility to sub synchronous oscillations (SSO). This paper proposes a systematic procedure for mitigating the interactions between a DFIG and a series compensated transmission line using the phase imbalance compensation (PIC) concept. The impact of the series and parallel PIC on the resonance behaviour of the grid is first thoroughly investigated. Then, the influence of the system strength on the capabilities of the PIC to mitigate DFIG-SSR is assessed. Based on the findings a design framework which enables the systematic assessment of the series and parallel PIC for mitigating DFIG-SSR is developed and successfully implemented in the IEEE 39 bus system. Comparison between both concepts reveals that the parallel PIC is better suited to mitigate DFIG-SSR. The impedance based stability analysis and detailed time domain electromagnetic transient (EMT) simulations are used to screen and validate the results., Intelligent Electrical Power Grids

Integration of wind energy resources into the grid creates several challenges for power system dynamics. More specifically, Type-3 wind turbines are susceptible to subsynchronous control interactions (SSCIs) when they become radially connected to a series-compensated transmission line. SSCIs can cause disruptions in power generation and can result in significant damage to wind farm (WF) components and equipment. This paper proposes an approach to mitigate SSCIs using an online frequency scan, with optimized phase angles of voltage harmonic injection to maintain steady-state operation, to modify the controllers or the operating conditions of the wind turbine. The proposed strategy is simulated in PSCAD/EMTDC software on the IEEE second benchmark model for subsynchronous resonance. Simulation results demonstrate the effectiveness of this strategy by ensuring oscillations do not grow.

This paper reviews the basics of series compensation in transmission systems through a literature survey. The benefits that this technology brings to enhance the steady state and dynamic operation of power systems are analyzed. The review outlines the evolution of the series compensation technologies, from mechanically operated switches to line- and self-commutated power electronic devices, covering control issues, different applications, practical realizations, and case studies. Finally, the paper closes with the major challenges that this technology will face in the near future to achieve a fully decarbonized power system.

The phase imbalance compensation concept is proposed in literature as an alternative way to mitigate classical subsynchronous resonance (SSR) problems in series-compensated transmission lines. However, a fundamental analysis to determine this concept's ability to mitigate resonances between a doubly-fed induction generator (DFIG) and a series compensated transmission line, i.e., DFIG-SSR, is not reported in literature. Therefore, the objective of this paper is to investigate to which extent phase imbalance compensation is able to mitigate DFIG-SSR. For the phase imbalance compensation scheme, an analytical model that captures the relation between the level of series compensation, the degree of asymmetry between the compensated phases, and the resulting shift in resonance frequency is developed and validated using time domain simulations. Then, an optimisation framework is developed to search for an adequate level of compensation asymmetry, capable of mitigating the adverse interactions. The optimisation allows us to show that, even with the best set of parameters, phase imbalance compensation is not suitable for mitigating DFIG-SSR. The analytical model enables us to explain the underlying physical reasons for this and an attempt is made to explain why this concept is theoretically able to mitigate classical resonance issues. Lastly, directions for future research are identified., Intelligent Electrical Power Grids

The replacement of conventional generation by power electronics-based generation changes the dynamic characteristics of the power system. This results in, among other things, the increased susceptibility to subsynchronous oscillations (SSO). First, this paper discusses three recently emerging SSO phenomena, which arise due to the interactions between (1) a doubly-fed induction generator and a series compensated transmission system; (2) a voltage source converter (VSC) and a weak grid; and (3) nearby VSCs. A fundamental review of these phenomena resulted in the requirement for a reclassification of the existing SSO phenomena. This reclassification is proposed in this work and is based on interacting components identified using participation factor analysis for the distinct phenomena. Second, a critical review of the existing mitigation measures is performed for these phenomena, highlighting the advantages and disadvantages of the solutions. The influence of the wind speed, grid strength, number of wind turbines, and several converter controller parameters are also discussed. To assist equipment manufacturers, control design engineers, and system operators in selecting and designing effective mitigation measures, the existing solutions are categorized in control solutions, hardware solutions, and solutions based on system level coordination. Finally, perspectives on open issues conclude this paper., Intelligent Electrical Power Grids

This paper assesses the suitability of the phase imbalance concept as an alternative approach for series compensating a transmission line, with the goal to eliminate adverse subsynchronous interactions between a DFIG and the transmission system. The performance of this concept, under a predefined degree of asymmetry, is compared with the classical series compensation scheme. First, it is concluded that the phase imbalance concept can reduce subsynchronous oscillations, as this concept results in lower resonance frequencies, which in turn lead to increased damping. Second, as these resonance frequencies remain in the DFIG's negative resistance region, the subsynchronous oscillations cannot be fully mitigated., Virtual/online event due to COVID-19 Accepted author manuscript, Intelligent Electrical Power Grids

The replacement of conventional generation by power electronics-based generation changes the dynamic characteristics of the power system. This results in, among other things, the increased susceptibility to subsynchronous oscillations (SSO). First, this paper discusses three recently emerging SSO phenomena, which arise due to the interactions between (1) a doubly-fed induction generator and a series compensated transmission system; (2) a voltage source converter (VSC) and a weak grid; and (3) nearby VSCs. A fundamental review of these phenomena resulted in the requirement for a reclassification of the existing SSO phenomena. This reclassification is proposed in this work and is based on interacting components identified using participation factor analysis for the distinct phenomena. Second, a critical review of the existing mitigation measures is performed for these phenomena, highlighting the advantages and disadvantages of the solutions. The influence of the wind speed, grid strength, number of wind turbines, and several converter controller parameters are also discussed. To assist equipment manufacturers, control design engineers, and system operators in selecting and designing effective mitigation measures, the existing solutions are categorized in control solutions, hardware solutions, and solutions based on system level coordination. Finally, perspectives on open issues conclude this paper., Intelligent Electrical Power Grids

This paper assesses the suitability of the phase imbalance concept as an alternative approach for series compensating a transmission line, with the goal to eliminate adverse subsynchronous interactions between a DFIG and the transmission system. The performance of this concept, under a predefined degree of asymmetry, is compared with the classical series compensation scheme. First, it is concluded that the phase imbalance concept can reduce subsynchronous oscillations, as this concept results in lower resonance frequencies, which in turn lead to increased damping. Second, as these resonance frequencies remain in the DFIG's negative resistance region, the subsynchronous oscillations cannot be fully mitigated., Virtual/online event due to COVID-19 Accepted author manuscript, Intelligent Electrical Power Grids

The phase imbalance compensation concept is proposed in literature as an alternative way to mitigate classical subsynchronous resonance (SSR) problems in series-compensated transmission lines. However, a fundamental analysis to determine this concept's ability to mitigate resonances between a doubly-fed induction generator (DFIG) and a series compensated transmission line, i.e., DFIG-SSR, is not reported in literature. Therefore, the objective of this paper is to investigate to which extent phase imbalance compensation is able to mitigate DFIG-SSR. For the phase imbalance compensation scheme, an analytical model that captures the relation between the level of series compensation, the degree of asymmetry between the compensated phases, and the resulting shift in resonance frequency is developed and validated using time domain simulations. Then, an optimisation framework is developed to search for an adequate level of compensation asymmetry, capable of mitigating the adverse interactions. The optimisation allows us to show that, even with the best set of parameters, phase imbalance compensation is not suitable for mitigating DFIG-SSR. The analytical model enables us to explain the underlying physical reasons for this and an attempt is made to explain why this concept is theoretically able to mitigate classical resonance issues. Lastly, directions for future research are identified., Intelligent Electrical Power Grids

Series capacitors are used in transmission lines for enhancing power transmission limit. However, they complicate the line’s protection due to impedance change of the line, voltage inversion, current inversion and sub-synchronous oscillation. Distance and differential protections are used in different arrangements in transmission line protection. Often they are used together as main and backup protection. In this paper, the fault tree method is used to compare the reliability of three common transmission line protection schemes. The schemes considered here are distance (main)-distance (backup)(Z; Z), differential (main)-distance (backup) (delta;Z) and differential (main)-differential (backup) (delta;delta). Fault trees are used to calculate the reliability of protection schemes in terms of both unavailability and failure rate. The analyses show that, for series compensated lines, using distance protection reduces protection system reliability. Differential protection performs best in terms of reliability despite depending entirely on communication., QC 20191211, FPS12, SweGRIDS

Series capacitors are used in some transmission lines to raise the power transfer limit. If a fault occurs at a location behind which the total reactance is capacitive, the result is current inversion, also known as current reversal. In a current inversion, current leads the voltage instead of lagging it. The probability of current inversion increases with higher levels of compensation. In this paper, the effect of current inversion is studied in distance and differential protection of transmission lines. A 500 kV transmission line is modelled, with compensation levels of 70%, 100% and 140%. Phase to ground faults are applied with fault inception angles of 0, 60 and 90. It is shown that current inversion can cause serious problems with distance protection. Differential protection is not severely affected by current inversion. The protection schemes are significantly influenced by parameters of the capacitor bank overvoltage protection components, particularly the metal-oxide varistor., Part of ISBN 979-835033199-8QC 20191209, FPS12, SweGRIDS

Series capacitors are used in transmission lines for enhancing power transmission limit. However, they complicate the line’s protection due to impedance change of the line, voltage inversion, current inversion and sub-synchronous oscillation. Distance and differential protections are used in different arrangements in transmission line protection. Often they are used together as main and backup protection. In this paper, the fault tree method is used to compare the reliability of three common transmission line protection schemes. The schemes considered here are distance (main)-distance (backup)(Z; Z), differential (main)-distance (backup) (delta;Z) and differential (main)-differential (backup) (delta;delta). Fault trees are used to calculate the reliability of protection schemes in terms of both unavailability and failure rate. The analyses show that, for series compensated lines, using distance protection reduces protection system reliability. Differential protection performs best in terms of reliability despite depending entirely on communication., QC 20191211, FPS12, SweGRIDS

Series capacitors are used in some transmission lines to raise the power transfer limit. If a fault occurs at a location behind which the total reactance is capacitive, the result is current inversion, also known as current reversal. In a current inversion, current leads the voltage instead of lagging it. The probability of current inversion increases with higher levels of compensation. In this paper, the effect of current inversion is studied in distance and differential protection of transmission lines. A 500 kV transmission line is modelled, with compensation levels of 70%, 100% and 140%. Phase to ground faults are applied with fault inception angles of 0, 60 and 90. It is shown that current inversion can cause serious problems with distance protection. Differential protection is not severely affected by current inversion. The protection schemes are significantly influenced by parameters of the capacitor bank overvoltage protection components, particularly the metal-oxide varistor., Part of ISBN 979-835033199-8QC 20191209, FPS12, SweGRIDS

Series capacitors are used in transmission lines for enhancing power transmission limit. However, they complicate the line’s protection due to impedance change of the line, voltage inversion, current inversion and sub-synchronous oscillation. Distance and differential protections are used in different arrangements in transmission line protection. Often they are used together as main and backup protection. In this paper, the fault tree method is used to compare the reliability of three common transmission line protection schemes. The schemes considered here are distance (main)-distance (backup)(Z; Z), differential (main)-distance (backup) (delta;Z) and differential (main)-differential (backup) (delta;delta). Fault trees are used to calculate the reliability of protection schemes in terms of both unavailability and failure rate. The analyses show that, for series compensated lines, using distance protection reduces protection system reliability. Differential protection performs best in terms of reliability despite depending entirely on communication., QC 20191211Part of ISBN 978-1-7281-4781-9, FPS12, SweGRIDS

Series capacitors are used in some transmission lines to raise the power transfer limit. If a fault occurs at a location behind which the total reactance is capacitive, the result is current inversion, also known as current reversal. In a current inversion, current leads the voltage instead of lagging it. The probability of current inversion increases with higher levels of compensation. In this paper, the effect of current inversion is studied in distance and differential protection of transmission lines. A 500 kV transmission line is modelled, with compensation levels of 70%, 100% and 140%. Phase to ground faults are applied with fault inception angles of 0, 60 and 90. It is shown that current inversion can cause serious problems with distance protection. Differential protection is not severely affected by current inversion. The protection schemes are significantly influenced by parameters of the capacitor bank overvoltage protection components, particularly the metal-oxide varistor., Part of ISBN 979-835033199-8QC 20191209, FPS12, SweGRIDS

Series capacitors are used in transmission lines for enhancing power transmission limit. However, they complicate the line’s protection due to impedance change of the line, voltage inversion, current inversion and sub-synchronous oscillation. Distance and differential protections are used in different arrangements in transmission line protection. Often they are used together as main and backup protection. In this paper, the fault tree method is used to compare the reliability of three common transmission line protection schemes. The schemes considered here are distance (main)-distance (backup)(Z; Z), differential (main)-distance (backup) (delta;Z) and differential (main)-differential (backup) (delta;delta). Fault trees are used to calculate the reliability of protection schemes in terms of both unavailability and failure rate. The analyses show that, for series compensated lines, using distance protection reduces protection system reliability. Differential protection performs best in terms of reliability despite depending entirely on communication., QC 20191211Part of ISBN 978-1-7281-4781-9, FPS12, SweGRIDS

Series capacitors are used in some transmission lines to raise the power transfer limit. If a fault occurs at a location behind which the total reactance is capacitive, the result is current inversion, also known as current reversal. In a current inversion, current leads the voltage instead of lagging it. The probability of current inversion increases with higher levels of compensation. In this paper, the effect of current inversion is studied in distance and differential protection of transmission lines. A 500 kV transmission line is modelled, with compensation levels of 70%, 100% and 140%. Phase to ground faults are applied with fault inception angles of 0, 60 and 90. It is shown that current inversion can cause serious problems with distance protection. Differential protection is not severely affected by current inversion. The protection schemes are significantly influenced by parameters of the capacitor bank overvoltage protection components, particularly the metal-oxide varistor., Part of ISBN 979-835033199-8QC 20191209, FPS12, SweGRIDS

Series capacitors are used in transmission lines for enhancing power transmission limit. However, they complicate the line’s protection due to impedance change of the line, voltage inversion, current inversion and sub-synchronous oscillation. Distance and differential protections are used in different arrangements in transmission line protection. Often they are used together as main and backup protection. In this paper, the fault tree method is used to compare the reliability of three common transmission line protection schemes. The schemes considered here are distance (main)-distance (backup)(Z; Z), differential (main)-distance (backup) (delta;Z) and differential (main)-differential (backup) (delta;delta). Fault trees are used to calculate the reliability of protection schemes in terms of both unavailability and failure rate. The analyses show that, for series compensated lines, using distance protection reduces protection system reliability. Differential protection performs best in terms of reliability despite depending entirely on communication., QC 20191211Part of ISBN 978-1-7281-4781-9, FPS12, SweGRIDS

Series capacitors are used in some transmission lines to raise the power transfer limit. If a fault occurs at a location behind which the total reactance is capacitive, the result is current inversion, also known as current reversal. In a current inversion, current leads the voltage instead of lagging it. The probability of current inversion increases with higher levels of compensation. In this paper, the effect of current inversion is studied in distance and differential protection of transmission lines. A 500 kV transmission line is modelled, with compensation levels of 70%, 100% and 140%. Phase to ground faults are applied with fault inception angles of 0, 60 and 90. It is shown that current inversion can cause serious problems with distance protection. Differential protection is not severely affected by current inversion. The protection schemes are significantly influenced by parameters of the capacitor bank overvoltage protection components, particularly the metal-oxide varistor., Part of ISBN 979-835033199-8QC 20191209, FPS12, SweGRIDS

This paper proposes an H∞ damping controller for the doubly-fed induction generator (DFIG) based wind farm (WF) to mitigate sub-synchronous control interactions (SSCI) with series capacitor compensated lines. A multi-input multi-output (MIMO) uncertain state-space model is developed to reflect the main SSCI characteristics considering the uncertainties of wind speed, series compensation (SC) levels and system parameters. The SSCI is analyzed using the eigenvalue analysis of the uncertain system model. In order to damp the SSCI between the WF and series capacitor compensated lines under uncertainties, an H∞ damping controller is designed for the rotor side converter (RSC). The weighting functions are designed to meet the mitigation requirements of sub-synchronous oscillation currents and output power. The robust stability (RS) and robust performance (RP) of the system are validated by the µ analysis. The performance of the H ∞ damping controller is demonstrated by time domain simulations of a 90 MW wind farm model with different wind speed, and SC levels. The case study with 6 m/s wind speed and 70% SC level shows superior performance of the H∞ damping controller.

Series compensation is extensively applied to the transmission lines to increase the power transfer capability of transmission lines, reduce transmission losses, improve voltage profiles, and improve power oscillation damping and transient stability of power systems. But it modifies the apparent impedance of the transmission lines during fault conditions and might cause the distance protection of transmission lines to encounter directional discrimination issues and reach problems. The non-linear characteristic of metal oxide varistor in series compensation model creates further complexity to the fault analysis and might affects the performance of conventional distance protection scheme. The distance protection issues in the series compensated lines need to be addressed for the reliable and sustainable operation of power system.The directional discrimination issues related to current inversion and voltage inversion phenomenon, and reach problems related to sub-synchronous oscillation phenomenon are addressed in this thesis report. This report aims to analyse the impacts of series compensation on the performance of conventional distance relays, and proposes a new protection solution to mitigate the shortcomings of distance relays in the series compensated lines. The proposed new protection solution includes: new tripping characteristic of quadrilateral distance relays to cope with the steady-state reach problems due to current or voltage inversion, and a new high-pass filtering technique to handle the transient reach problems due to SSO.The proposed new protection algorithm is developed in MATLAB. The performance of new protection algorithm is evaluated by simulating a 500 kV two-source power system with a 200 km series compensated line in EMTDC/ PSCAD (Manitoba Hydro). The proposed new protection solution is found to be beneficial., Seriekompensation tillämpas i stor utsträckning på överföringsledningarna för att öka överföringsförmågan hos överföringsledningar, minska överföringsförluster, förbättra spänningsprofiler och förbättra effektdämpning och övergående stabilitet hos elsystem. Men det ändrar transmissionslinjernas uppenbara impedans under felförhållanden och kan orsaka att distansskydd för överföringsledningarna stöter på diskrimineringsproblem och uppnår problem. Den icke-linjära egenskapen hos metalloxidvaristor i seriekompensationsmodell skapar ytterligare komplexitet för felanalysen och kan påverka prestandan hos konventionella distansskyddssystem. Distansskydd problemen i seriekompenserade linjer måste lösas för en pålitlig och hållbar drift av elsystemet. De riktningsdiskrimineringsproblem som är relaterade till det aktuella inversions- och spänningsinversionsfenomenet och uppnår problem relaterade till subsynkron oscillationsfenomen tas upp i denna avhandlingsrapport. Denna rapport syftar till att analysera effekterna av seriekompensation för prestanda hos konventionella distansreläer och föreslår en ny skyddslösning för att mildra bristerna i distansreläerna i seriekompenserade linjer. Den föreslagna nya skyddslösningen innefattar: Ny utlösningskaraktäristik för fyrsidig distansreläer för att klara avståndet med stillastående / räckvidden på grund av ström- eller spänningsinversion och en ny högpassfiltreringsteknik för hantering av övergående över- Nå problem på grund av SSO. Den föreslagna nya skyddsalgoritmen har utvecklats i MATLAB. Utförandet av den nya skyddsalgoritmen utvärderas genom simulering av ett 500 kV två-källa kraftverk med en 200 km serie kompenserad linje i EMTDC / PSCAD (Manitoba Hydro). Den föreslagna nya skyddslösningen har visat sig vara fördelaktig.

Series compensation is extensively applied to the transmission lines to increase the power transfer capability of transmission lines, reduce transmission losses, improve voltage profiles, and improve power oscillation damping and transient stability of power systems. But it modifies the apparent impedance of the transmission lines during fault conditions and might cause the distance protection of transmission lines to encounter directional discrimination issues and reach problems. The non-linear characteristic of metal oxide varistor in series compensation model creates further complexity to the fault analysis and might affects the performance of conventional distance protection scheme. The distance protection issues in the series compensated lines need to be addressed for the reliable and sustainable operation of power system.The directional discrimination issues related to current inversion and voltage inversion phenomenon, and reach problems related to sub-synchronous oscillation phenomenon are addressed in this thesis report. This report aims to analyse the impacts of series compensation on the performance of conventional distance relays, and proposes a new protection solution to mitigate the shortcomings of distance relays in the series compensated lines. The proposed new protection solution includes: new tripping characteristic of quadrilateral distance relays to cope with the steady-state reach problems due to current or voltage inversion, and a new high-pass filtering technique to handle the transient reach problems due to SSO.The proposed new protection algorithm is developed in MATLAB. The performance of new protection algorithm is evaluated by simulating a 500 kV two-source power system with a 200 km series compensated line in EMTDC/ PSCAD (Manitoba Hydro). The proposed new protection solution is found to be beneficial., Seriekompensation tillämpas i stor utsträckning på överföringsledningarna för att öka överföringsförmågan hos överföringsledningar, minska överföringsförluster, förbättra spänningsprofiler och förbättra effektdämpning och övergående stabilitet hos elsystem. Men det ändrar transmissionslinjernas uppenbara impedans under felförhållanden och kan orsaka att distansskydd för överföringsledningarna stöter på diskrimineringsproblem och uppnår problem. Den icke-linjära egenskapen hos metalloxidvaristor i seriekompensationsmodell skapar ytterligare komplexitet för felanalysen och kan påverka prestandan hos konventionella distansskyddssystem. Distansskydd problemen i seriekompenserade linjer måste lösas för en pålitlig och hållbar drift av elsystemet. De riktningsdiskrimineringsproblem som är relaterade till det aktuella inversions- och spänningsinversionsfenomenet och uppnår problem relaterade till subsynkron oscillationsfenomen tas upp i denna avhandlingsrapport. Denna rapport syftar till att analysera effekterna av seriekompensation för prestanda hos konventionella distansreläer och föreslår en ny skyddslösning för att mildra bristerna i distansreläerna i seriekompenserade linjer. Den föreslagna nya skyddslösningen innefattar: Ny utlösningskaraktäristik för fyrsidig distansreläer för att klara avståndet med stillastående / räckvidden på grund av ström- eller spänningsinversion och en ny högpassfiltreringsteknik för hantering av övergående över- Nå problem på grund av SSO. Den föreslagna nya skyddsalgoritmen har utvecklats i MATLAB. Utförandet av den nya skyddsalgoritmen utvärderas genom simulering av ett 500 kV två-källa kraftverk med en 200 km serie kompenserad linje i EMTDC / PSCAD (Manitoba Hydro). Den föreslagna nya skyddslösningen har visat sig vara fördelaktig.