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Continuous expansion in the scale of high-voltage flexible direct current (DC) transmission systems has resulted in higher requirements for clearing fault currents. The hybrid DC circuit breaker, as the most promising DC circuit breaker, can effectively isolate and remove the faults that occur in DC power grids. At present, hybrid DC circuit breakers can be divided into two types: two port and multiport. Two-port DC circuit breakers are used in a single line and have the advantages of simple and flexible control. Multiport DC circuit breakers are used at the DC bus and control the fault isolation operation of multiple lines connected to the bus. When compared to two-port DC circuit breakers, multiport DC circuit breakers significantly reduce the number of configurations, reduce costs, and occupy less space. First, this article classifies hybrid DC circuit breakers into two-port and multiport categories, and refines and organizes the two major categories. Then, it analyzes the functionality, reliability, control complexity, and economy of each scheme based on the topology structures proposed in the current literature. Finally, prospects for future research on hybrid DC circuit breakers are presented. [ABSTRACT FROM AUTHOR]

Lightning represents the primary threat to power grids, with approximately 80% of natural occurrences being multi-lightning strikes, which have been extensively studied and confirmed to pose even more severe hazards. Hybrid DC circuit breakers (DCCBs) exhibit promising application prospects due to their superior interruption performance. During multi-lightning strikes, lightning intrusive waves pose a greater threat to the insulation of equipment such as hybrid DC fuses, fast mechanical switches, and insulated gate bipolar transistors. Therefore, this paper establishes a simulation model using the Real-Time Digital Simulator based on the model and parameters of the DCCB in the ± 500 kV Zhangbei HVDC project in China. It analyzes the lightning intrusive waves on the DCCB and investigates the energy absorption of metal oxide varistors (MOVs) in the energy-consuming branch of the DCCB under multi-lightning strikes, as well as the overvoltage levels of various branches of the DCCB under such conditions. The research results indicate that the energy-consuming branch has a certain tolerance to multi-lightning strikes. However, if the MOV collapses under multi-lightning strikes, it can lead to severe overvoltage issues. Therefore, the design and selection of DCCBs should fully consider the impact of multi-lightning strikes. [ABSTRACT FROM AUTHOR]

To address the technical challenge of rapid and reliable interruption of DC faults in offshore wind power DC collection and transmission systems, which are critical for large-scale renewable energy integration, this paper proposes an integrated multi-port DC circuit breaker (DCCB) with bus fault clearing capability based on a dual H-bridge configuration. By extending a pair of bridge arms in the H-bridge to connect to the DC bus and employing diodes in the load commutation switches (LCSs) to form the second H-bridge, the proposed DCCB not only achieves conventional line fault clearing but also has the ability to interrupt bus faults. A five-terminal offshore wind power DC transmission system simulation model was built in PSCAD/EMTDC to verify the performance of the DCCB under various operating conditions. The results demonstrate that the proposed multi-port DCCB can protect multiple DC lines effectively under different conditions. [ABSTRACT FROM AUTHOR]

Aiming at the problems of high peak value fault current, fast rising speed, and being unable to ensure the reliability of the power supply in the non-fault zone in a multi-terminal DC system, a new cascade flexible current limiter and mechanical DC circuit breaker for medium- and high-voltage distribution networks are proposed. Firstly, the flexible current limiter is triggered by differential under-voltage protection to achieve the effect of interpole voltage clamping, suppressing the fault current and improving the dynamic recovery characteristics of the DC system after fault clearing. Secondly, according to the breaking speed of the DC circuit breaker, the action time of the current limiter can be set flexibly. The directional pilot protection signal of the circuit breaker is used to ensure the continuous action of the current limiter at the converter station side in the fault zone, until the circuit breaker acts to isolate the fault. The protection strategy can also avoid the blocking of the converter station and reduce the requirements for the breaking speed and breaking capacity of the circuit breaker. Finally, a four-terminal medium voltage distribution network model is built in MATLAB/SIMULINK, and the effect of the current limiter and the feasibility of the proposed protection strategy are verified by simulation. [ABSTRACT FROM AUTHOR]

To address the technical challenge of rapid and reliable interruption of DC faults in offshore wind power DC collection and transmission systems, which are critical for large-scale renewable energy integration, this paper proposes an integrated multi-port DC circuit breaker (DCCB) with bus fault clearing capability based on a dual H-bridge configuration. By extending a pair of bridge arms in the H-bridge to connect to the DC bus and employing diodes in the load commutation switches (LCSs) to form the second H-bridge, the proposed DCCB not only achieves conventional line fault clearing but also has the ability to interrupt bus faults. A five-terminal offshore wind power DC transmission system simulation model was built in PSCAD/EMTDC to verify the performance of the DCCB under various operating conditions. The results demonstrate that the proposed multi-port DCCB can protect multiple DC lines effectively under different conditions.

AbstractDc microgrids (MG) have drawn more attention due to the demand for renewable energy sources, energy storage devices in distributed generation, and the separation of DC loads requiring more power converters. This system needed protection DC circuit breakers (DCCB) that could quickly isolate the faults in the system. These devices must be as small and light as possible but should only produce low power loss during the ON state. The impedance source DC circuit breaker was introduced as an improved structure (SSCB) which provided automatic turns off without needing external command due to its natural commutation operation principle. In addition, it had many advantages such as faster response, simpler control design, restricted fault current magnitude, which makes the system more fault-resilient, the fault current will not affect the source or the SCR, coordination of cascaded breakers is automatic, and convenience for protection with power converters. This paper presents different impedance source DC circuit breakers such as ZCB, ΓCB, TCB, and YCB. It will show their benefits and drawbacks, which could be used as a helping guide while choosing which type of impedance source DC circuit breakers is suitable for a specific application.

Precisely assessing plasma parameters holds paramount importance in investigating the arc extinguishing mechanism of semi-sealed splitter plate DC circuit breakers, refining the configuration of splitter plates, and optimizing the overall structural design of circuit breakers. Based on the principle of the Langmuir probe, a double probe diagnostic method is proposed to investigate the air arc plasma in the opening process of a DC circuit breaker. The diagnostic circuit of the probes is designed, and three sets of double probes are arranged to trace the evolution of the plasma density during the opening process. The research reveals that the plasma center density, measured by the diagnostic system during the opening process of the DC circuit breaker, is about 1022 m−3–1023 m−3. This density is compared with the diagnostic results obtained by other methods, confirming the accuracy of the Langmuir double probe for plasma measurements in the DC circuit breaker. The study also revealed an exponential decay behavior of electron density along the radial direction of the arc. A mathematical model was employed to describe this phenomenon, establishing a relationship between the distribution of electron density and arc current. [ABSTRACT FROM AUTHOR]

[Objective] DC circuit breaker is a key equipment in metro traction power supply system. To improve the reliability of the traction and power supply system through reasonable maintenance strategy, it is necessary to evaluate the health condition of DC circuit breaker accurately. [Method] Health indexes are used to characterize the overall health condition of the equipment and establish a comprehensive evaluation model of the equipment health condition. On the basis that the changes of the equipment characteristic parameters reflect the equipment health condition, evaluation indexes are reasonably selected and a multi-index evaluation system of equipment operating condition is established. With the method of hierarchy and entropy weight, the calculation method of the weight of each sub-index is improved, making the equipment health condition evaluation model more reasonable. The equipment health index is calculated based on the evaluation model, and the service life model based on historical health data is established to fit the trend of the equipment health index, evaluate the future health condition and predict the remaining service life. The proposed evaluation model is validated by the actual data of a traction substation. [Result & Conclusion] The example analysis results show that the proposed evaluation model of DC circuit breaker is effective and rational to some extent in that it can scientifically judge and predict the healthy condition and remaining service life of the DC circuit breaker.

The multi-terminal modular multi-level converter-based high voltage direct current (MMC-HVDC) grid with short circuit protection equipment (SCPE) is so complex that it is difficult to estimate its fault current and analyze the performance of SCPE by conventional time-domain numerical calculation method, it meets three big obstacles. This paper has made significant progress in overcoming these obstacles. 1). By applying the modern electrical circuit theory, a systematic formulation of the differential equation set for fault current calculation is developed to avoid a lot of complex and cumbersome matrix manual calculations. 2). A novel Y-Delta transformation in the s-domain is proposed to develop an eliminating virtual node approach for a complex MMC-HVDC grid, including the ring, radial, and hybrid topologies. 3). It is difficult to solve the equivalent circuit of MMC-HVDC grid with SCPE since SCPE is a timevariable-nonlinear circuit. A canonical voltage source model of SCPE is established to transform the time-variable-nonlinear circuit into a piecewise linear circuit. Based on the three significant progresses, a DC fault current fast-computing method of MMC-HVDC grid with SCPE is put forward to deal with all kinds of MMC-HVDC grids with several kinds of SCPEs. Then, the performance of several kinds of SCPE is analyzed and compared by this method. Consequently, the proposed DC fault current fast-computing method is a new powerful tool to estimate the fault current of MMC-HVDC grid and analyze the performance of SCPE. [ABSTRACT FROM AUTHOR]

In recent years, with the rapid development of high-voltage flexible direct current (DC) transmission systems, more and more multi-port high-voltage DC systems have been successfully put into operation. Therefore, the number of connecting ports on the DC bus is gradually increasing, which necessitates higher requirements for clearing fault current. To better protect the DC power grid, this paper integrates a DC fault current limiter with a multi-port DC circuit breaker. This article proposes a modular cascaded multi-port hybrid DC circuit breaker topology. It also elaborates on the topology structure, working principle, and control program under three different fault conditions. It completes the theoretical derivation and analysis of the circuit breaker fault isolation process, as well as the parameter design of the core components. Finally, a model is established in PSCAD/EMTDC for simulation verification. The application performance of the circuit breaker in four-terminal DC systems is studied and analyzed, and the current-limiting effect of the multi-port DC circuit breaker proposed in this article is demonstrated. In addition, the disconnection performance and energy consumption of the arrester have been improved to a certain extent, which has good feasibility and economy. [ABSTRACT FROM AUTHOR]

[Objective] DC circuit breaker is a key equipment in metro traction power supply system. To improve the reliability of the traction and power supply system through reasonable maintenance strategy, it is necessary to evaluate the health condition of DC circuit breaker accurately. [Method] Health indexes are used to characterize the overall health condition of the equipment and establish a comprehensive evaluation model of the equipment health condition. On the basis that the changes of the equipment characteristic parameters reflect the equipment health condition, evaluation indexes are reasonably selected and a multi-index evaluation system of equipment operating condition is established. With the method of hierarchy and entropy weight, the calculation method of the weight of each sub-index is improved, making the equipment health condition evaluation model more reasonable. The equipment health index is calculated based on the evaluation model, and the service life model based on historical health data is established to fit the trend of the equipment health index, evaluate the future health condition and predict the remaining service life. The proposed evaluation model is validated by the actual data of a traction substation. [Result & Conclusion] The example analysis results show that the proposed evaluation model of DC circuit breaker is effective and rational to some extent in that it can scientifically judge and predict the healthy condition and remaining service life of the DC circuit breaker. [ABSTRACT FROM AUTHOR]

The multi-terminal modular multi-level converter-based high voltage direct current (MMC-HVDC) grid with short circuit protection equipment (SCPE) is so complex that it is difficult to estimate its fault current and analyze the performance of SCPE by conventional time-domain numerical calculation method, it meets three big obstacles. This paper has made significant progress in overcoming these obstacles. 1). By applying the modern electrical circuit theory, a systematic formulation of the differential equation set for fault current calculation is developed to avoid a lot of complex and cumbersome matrix manual calculations. 2). A novel Y-Delta transformation in the s-domain is proposed to develop an eliminating virtual node approach for a complex MMC-HVDC grid, including the ring, radial, and hybrid topologies. 3). It is difficult to solve the equivalent circuit of MMC-HVDC grid with SCPE since SCPE is a time-variable-nonlinear circuit. A canonical voltage source model of SCPE is established to transform the time-variable-nonlinear circuit into a piecewise linear circuit. Based on the three significant progresses, a DC fault current fast-computing method of MMC-HVDC grid with SCPE is put forward to deal with all kinds of MMC-HVDC grids with several kinds of SCPEs. Then, the performance of several kinds of SCPE is analyzed and compared by this method. Consequently, the proposed DC fault current fast-computing method is a new powerful tool to estimate the fault current of MMC-HVDC grid and analyze the performance of SCPE.

Dc microgrids (MG) have drawn more attention due to the demand for renewable energy sources, energy storage devices in distributed generation, and the separation of DC loads requiring more power converters. This system needed protection DC circuit breakers (DCCB) that could quickly isolate the faults in the system. These devices must be as small and light as possible but should only produce low power loss during the ON state. The impedance source DC circuit breaker was introduced as an improved structure (SSCB) which provided automatic turns off without needing external command due to its natural commutation operation principle. In addition, it had many advantages such as faster response, simpler control design, restricted fault current magnitude, which makes the system more fault-resilient, the fault current will not affect the source or the SCR, coordination of cascaded breakers is automatic, and convenience for protection with power converters. This paper presents different impedance source DC circuit breakers such as ZCB, ΓCB, TCB, and YCB. It will show their benefits and drawbacks, which could be used as a helping guide while choosing which type of impedance source DC circuit breakers is suitable for a specific application. General Statement: The Impedance source circuit breakers are developed from the solid-state DC circuit breakers. They had been preferred over the traditional types of DCCB in protection systems because of their various advantages, such as the fastest response that could isolate the fault in microseconds, automatically isolated without needing external control or sensing elements, and so forth. This paper is the first review paper on the different kinds of Impedance source circuit breakers. It also presents different impedance source DC circuit breakers such as ZCB, ΓCB, TCB, and YCB. Moreover, showing their benefits and drawbacks. So, it provided a helping guide when choosing an impedance source DC circuit breaker suitable for a specific application or as a reference guide for additional research or topological enhancements. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the penetration of distributed energy resources (DER) has increased, research on direct current (DC) power transmission and distribution has been actively performed. The DC system has the advantage of high-power transmission efficiency. However, it has a very large and rapid increase in fault current in the DC system directly after a fault occurs. As one of the countermeasures, studies on the application of the superconducting fault current limiter (SFCL) into the DC system have been conducted to protect major facilities from DC fault current, which is expected to alleviate the power burden on the DC circuit breaker through its quench operation. Among the studied DC SFCLs, the trigger-type DC SFCL using a transformer, which can achieve the peak DC fault current-limiting operation, has been suggested. However, the DC fault current-limiting operation, in the case of the DC SFCL with a current-limiting reactor (CLR), was analyzed to not be effectively executed in the steady state since the transient state directly follows the fault occurrence. In this paper, the DC fault current-limiting operation of a twice-quench trigger type SFCL using a transformer considering magnetizing current and its CLR was analyzed. Through DC fault current-limiting experiments according to the inductance of its current-limiting reactor (CLR), the effective current-limiting design of twice-quench trigger type SFCL using a transformer was described. [ABSTRACT FROM AUTHOR]

While traditional AC mechanical circuit breakers can protect AC circuits, many other DC power distribution technologies, such as DC microgrids (MGs), yield superior disruption performance, e.g., faster and more reliable switching speeds. However, novel DC circuit breaker (DCCB) designs are challenging due to the need to quickly break high currents within milliseconds, caused by the high fault current rise in DC grids compared to AC grids. In DC grids, the circuit breaker must not provide any current crossing and must absorb surges, since the arc is not naturally extinguished by the system. Additionally, the DC breaker must mitigate the magnetic energy stored in the system inductance and withstand residual overvoltages after current interruption. These challenges require a fundamentally different topology for DCCBs, which are typically made using solid-state semiconductor technology, metal oxide varistors (MOVs), and ultra-fast switches. This study aims to provide a comprehensive review of the development, design, and performance of DCCBs and an analysis of internal topology, the energy absorption path, and subcircuits in solid-state (SS)-based DCCBs. The research explores various novel designs that introduce different structures for an energy dissipation solution. The classification of these designs is based on the fundamental principles of surge mitigation and a detailed analysis of the techniques employed in DCCBs. In addition, our framework offers an advantageous reference point for the future evolution of SS circuit breakers in numerous developing power delivery systems. [ABSTRACT FROM AUTHOR]

With the continuous application and popularization of distributed energy, DC power distribution will become the mainstream form of future power distribution system. As a new type of power distribution system, the overvoltage and insulation coordination of flexible DC power distribution urgently needs further research and improvement. The addition of medium-voltage DC circuit breakers has also led to fundamental changes in the operating overvoltage transient characteristics of the system. It is necessary to analyze the operating overvoltage distribution characteristics and insulation coordination of the flexible DC distribution network with DC circuit breakers. Firstly, the electromagnetic transient simulation model of ±10 kV ring-network flexible DC power distribution network is constructed, and the protection action scheme based on DC circuit breaker is designed. Then, the ±10 kV ring network flexible DC power distribution system is simulated and analyzed for operating overvoltage, horizontal spatial distribution characteristics of its amplitude and the decisive working condition of the maximum overvoltage at key positions are obtained, insulation coordination scheme of the ±10 kV ring network flexible DC power distribution system is proposed. Finally, the simulation analysis of the transient induced overvoltage of the DC cable sheath under the influence of the action of the DC circuit breaker is carried out. The results show that the addition of DC circuit breakers improves the reliability and flexibility of DC distribution network, and the layout of arrester and cable metal shield protector is further optimized, which is of great significance to the design of insulation matching scheme of flexible direct distribution network of ring network.

The stability of opening process of fast mechanical switch is the key factor affecting the breaking performance of DC circuit breaker. Based on the finite element method, the multi-field coupling calculation of electromagnetic, thermal and momentum is carried out for the opening process of high current fast switch with permanent magnet operating mechanism and electromagnetic repulsion mechanism. The influence of the driving coil input for the permanent magnet operating mechanism and different driving coil currents on the opening process of double-action mechanism are analyzed. The calculation results show that the permanent magnet suction force can be cancelled in advance when the driving coil of the permanent magnet operating mechanism is put in, thereby avoiding the opening spring back phenomenon caused by the electromagnetic repulsion force due to the short working time. Because the electromagnetic repulsion force is very large at the initial stage of opening, the driving coil input of the permanent magnet operating mechanism has little influence on the initial speed of opening. After the electromagnetic repulsion disappears, the greater the driving coil current of the permanent magnet operating mechanism is, the greater the speed to reach the rated opening distance after the electromagnetic repulsion force disappearing. In order to avoid opening rebound phenomenon, the current value of the driving coil should be selected reasonably. The comparison between the simulation results and the opening process characteristic curves of the actual prototype shows that two curves are in good agreement, which verifies the correctness of the simulation method.

This paper presents two improved circuit breaker (CB) topologies based on resonant networks for medium voltage DC (MVDC) applications, such as shipboard power distribution and subsea oil and gas production. The topologies feature simple LC resonant networks that efficiently suppress fault current in just a few tens of microseconds, making them suitable for integration with existing solid-state or hybrid DC CB. Moreover, they also help to minimize the CB energy and reduce (if not eliminate) the requirement for protection devices like surge arresters during fault events. The proposed topologies are first tested using Typhoon Hardware-in-the-Loop (HiL) simulations at 1.2 MW (6 kV, 200 A) power levels and thyristor-based solid-state circuit breakers (SSCB). Then, scaled-down laboratory prototypes, also based on thyristor-based SSCB, are experimentally validated. The results show that both topologies quickly bring the current of the CB’s main switch to 0 A. The main circuit pathway requires only a small inductor and switch, resulting in a steady-state efficiency of $>$ 99.9%. The resonant network-based design allows for a fast response time of less than $50 \mu \text{s}$ using a simple and low-cost auxiliary circuit, eliminating the need for complex charging circuitry and protection devices typically used to suppress voltage surges during faults.

In the advent of recent developments in a higher efficiency Direct Current (DC) system, the DC microgrid proves to be a permissible future to match the load demand with distributed power generation. The distribution of the DC power system benefits more than the Alternate Current (AC) power system, and due to recent developments, many researchers focus on DC microgrid. DC microgrid system has the advantage of direct interfacing with Renewable energy sources (RES) and energy storage systems (ESS), making the system highly efficient and distinct. Since the protective devices used in AC power systems do not support DC applications, there are challenges in designing and implementing a proper protection device for DC microgrid, which includes the breaking of fault current and the rapid response in handling fault current, capability to overcome the fault and cost of implementing. Unlike traditional circuit breakers that work with a fixed voltage source, Z-Source Breakers are capable of interrupting current in systems with variable voltage sources, making it appropriate for applications involving renewable energy sources, microgrids and energy storage systems. These breakers use a unique Z-Source network to provide enhanced flexibility and reliability in managing electrical faults in modern power grids. This study intends to analyses the recent growth in the impedance-based DC circuit breaker and DC microgrid’s fault characteristics.

The direct current circuit breaker (DCCB) is extensively employed in DC microgrid applications to protect the network during faults. However, numerous DC converters are combined in parallel to form a DC microgrid, which creates a large network inductance. The grid stores energy during regular operation, which repels instantaneous current breaking, and this stored energy needs to be eliminated after current breaking. Conventional topologies use different energy absorption methods to dissipate the stored energy after breaking the current. In this paper, an efficient bidirectional DC circuit breaker (EBDCCB) topology is introduced to extract and reuse this energy instead of dissipating it. The proposed topology has bidirectional power flow capability to meet the requirements of DC microgrid applications as energy storage devices are frequently utilized. Furthermore, EBDCCB shows drastically improved performance in terms of current breaking time, voltage stress, regenerated average current, and energy recovery efficiency compared to the conventional DCCB topology. The mathematical modeling and sizing of the components used in the proposed EBDCCB are elaborately analyzed, and detailed performance testing is presented along with extensive PSIM software simulation. Additionally, an experimental investigation is conducted on a laboratory-scale 48 V/1 A prototype. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Engineering Technology is the property of Editorial Department of Electric Power Engineering Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Power Engineering Technology is the property of Editorial Department of Electric Power Engineering Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For the problem of fault isolation and power flow control in DC grid, this paper proposes a DC power flow controllable multi-port DC circuit breaker. Under the normal operation, this breaker has the function of DC power flow regulation, which is used to regulate the power flow on DC lines. After the DC system fails, this breaker is equivalent to the hybrid DC breaker, which is used to cut off the fault current and isolate the fault line. In the paper, the steady-state power flow regulation mechanism and transient current interrupting mechanism of the breaker are described in detail. Finally, a meshed DC grid is built in PSCAD/ EMTDC simulation platform. The simulation results show that the proposed topology has good performance in power flow control and current interrupting.

As the utilization of DC systems increases worldwide, the importance of DC cutoff technology is increasing. We proposed a hybrid DC cutoff technology combining an SFCL (superconducting fault-current-limiter) and a mechanical DC circuit breaker. This model can perform a fault-current-limiting operation through the quenching of the SFCL and a breaking operation through an artificial cutoff zero point of a mechanical DC circuit breaker. In particular, the SFCL is responsible for the growth of the initial fault current according to the DC characteristics. As the DC system's supply and demand increase, the DC system's capacity also increases. Therefore, the fault-current-limiting capability of the SFCL should be increased according to the increasing DC system breaking capacity. The fault-current-limiting capability can be increased by increasing the superconducting wires used in the SFCL. Current commercially available SFCLs use bifilar-helical-type and bifilar-spiral-type winding methods. These have the disadvantage of increased volume with increased capacity. To compensate for these disadvantages, we proposed a bifilar-meander-type winding method. In this paper, a new bifilar-meander-type winding method was introduced. In addition, the structural and electromagnetic parts of the existing winding method and the bifilar-meander-type winding method were compared and analyzed for differences. The program used for this analysis is the electromagnetic analysis Maxwell program. As a result, it was confirmed that the bifilar-meander-type winding method is superior to the conventional bifilar-helical and bifilar-spiral types. [ABSTRACT FROM AUTHOR]

In order to further optimize the rigid split speed and starting time of high voltage direct current (HVDC) circuit breaker and improve the motion characteristics of electromagnetic repulsion mechanism(ERM). An enhanced three coil ERM with electromagnetic suction as driving force was proposed. Kinematics, transient electromagnetic field and circuit were used for mathematical model coupling analysis. The two-dimensional model was established by using finite element analysis software solve its motion characteristics. It was verified by simulation test. Firstly, the influence of different parameters on its motion characteristics was analyzed. Secondly, the influence of closing coil intervention time on its motion characteristics was analyzed. Finally, the difference of motion characteristics between enhanced three coil model and double coil model was compared. The results show that travel time can be shortened by increasing the capacitance and voltage, among three coils, optimization effect of changing the driving circuit parameters of the moving coil is the best. The electromagnetic driving force can be increased by appropriately increasing the number of turns and section width of the coil, and shorten the starting time. Intervening from time 0 can maximize the motion speed of the mechanism. Under the same parameters, the three coil model can complete 25 mm stroke in 2 ms, The double coil model can complete 16 mm stroke in 2 ms. [ABSTRACT FROM AUTHOR]

This article presents a novel circuit configuration of a high-voltage direct current circuit breaker (HVdcCB) test bench that is based on a modified H-bridge modular multilevel cascaded converter (MMCC). The modified MMCC is composed of fewer H-bridge cells, and it can be reconfigured during operation to allow the proposed test bench to output large current or high voltage for the current breaking and dielectric withstand tests. Although simultaneous output of large current and high voltage is not possible, the maximum transient interrupt voltage (TIV) withstand test can be performed with reduced ratings. The controllable output allows generation of complex waveforms to simulate a wide range of fault conditions. Furthermore, the modified MMCC has some inherent safety features that can reduce the need for additional protective equipment in case of operational failure of the HVdcCB. In contrast, the conventional charged capacitor and inductor-based designs cannot generate arbitrary waveforms, are only suitable for current breaking tests, and require additional circuits to generate initial conditions for the HVdcCB. AC short-circuit generator-based designs offer one degree of freedom for control of the output waveforms and can sustain the maximum TIV withstand test. However, the ac output is unsuitable for the dielectric withstand test, and additional circuits are required to provide initial conditions for the HVdcCB. The proposed test bench circuit configuration is verified using a downscaled experimental test bench that consists of a total of nine H-bridge cells with an equivalent switching frequency of 92.5 kHz. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the DC fault transient study of a meshed DC grid with high-temperature superconducting (HTS) HVDC cables to integrate offshore wind power. A four-terminal meshed DC grid model with a ±100 kV DC voltage rating is developed. DC circuit breakers (DCCBs) are implemented in the DC grid to deal with DC cable faults. To conduct the fault transient study, the fault scenarios with different fault locations and protection delays are studied. The sensitivity study versus different DC fault locations reveals that the faults on the faulted cable will not cause the quenching of healthy cables. The sensitivity study considering different DC fault protection delays demonstrates that the HTS cables have a current-limiting effect and the long delay of DC fault protection does not result in large fault current and the quenching of healthy cables. Extensive simulations in PSCAD/EMTDC validate the founding. [ABSTRACT FROM AUTHOR]

Numerous problems have emerged with the development of HVDC transmission technology. One of them is the fault current that occurs when there is an issue in the line. In particular, in the case of a PTP (pole-to-pole) fault, a DCCB design suitable for the direction is required because the fault current flows through the positive and negative poles. In the case of PTP fault, a fault current of the same value occurs in the opposite direction, and in the case of DCCB, the breaking efficiency may be reduced or even impossible to break due to a mistake in the emission direction or a wrong design. In particular, when designing using several unidirectional DCCBs, it is cheaper and consumes less area than typical DCCBs, so it is economical, but this problem may be more prominent. To solve this problem, this paper proposes a 4- pole Hybrid HVDC circuit breaker to solve this problem. This circuit optimizes the DCCB internal components through quantitative analysis of the fault current to reduce the influence of the residual fault current as well as the previously most important parameter, Zero-Cross Time (ZCT). We also verified the circuit’s energy dissipation process to increase reliability. The circuit in this paper is simulated based on the VSC-based HVDC transmission link. Physically analyze the derived results and described the circuit mechanism.

This paper proposes a novel circuit configuration for a high-voltage direct-current circuit breaker (HVDCCB) test bench that differs significantly from conventional test benches. The proposed test bench consists of a modular multilevel cascaded converter (MMCC) that is based on H-bridge cells, an output inductor, and an auxiliary capacitor bank. The proposed test bench is capable of generating controllable output currents up to several kiloamperes and output voltages up to several hundred kilovolts because each MMCC cell is operated by phase-shifted pulse-width-modulated (PSPWM) signals. Consequently, the proposed test bench can simulate a wide range of fault conditions within hardware limitations to test different HVDCCB types with various current and voltage ratings. The flexibility of the proposed test bench is complemented by a longer service lifetime with inherent circuit protection in the case of operational failure of the HVDCCB. The concept of the proposed test bench is verified experimentally on a downscaled test bench that consists of nine H-bridge cells and operates at an equivalent switching frequency of $\mathrm {92.5 kHz }$ .

This paper proposes a thyristor-based hybrid DC circuit breaker (HDCCB), which is composed of a fast mechanical circuit breaker and an LC resonant circuit with thyristor switches. The proposed HDCCB provides a zero-crossing point for fault current by injecting a resonant current in the reverse direction of the fault current. The proposed HDCCB has a low conduction loss in normal operation using a mechanical circuit breaker, and it offers the advantages of low cost, high reliability, and large capacity using thyristor switches instead of IGBT switches. It also has the design flexibility to adjust the magnitude of the injection current depending on the fault current level. A bidirectional HDCCB is also proposed by adding several components to the developed unidirectional HDCCB, which can offer compact system size and low system cost. Design considerations of the proposed structure are discussed. The validity of the proposed HDCCB is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Piezoelectrically actuated fast mechanical switches provide a low-loss conduction path in hybrid circuit breakers for protecting medium-voltage direct-current systems. As the desired actuation speed approaches the driving limit of a piezoelectric actuator, excessive vibration starts to dominate its underdamped travel curves, resulting in insulation failures and delayed switching in the fast mechanical switch. To improve the underdamped travel curves into critically damped travel curves, several switching motion control schemes with active damping filters are proposed in this paper. The switching motion controllers are based on an electromechanical model of a fast mechanical switch with experimentally identified parameters. According to hardware implementation tests, the proposed closed-loop control schemes optimized the switch travel curves with a 56% reduction in the undershoot and a 75% reduction in the settling time. Equipped with the critically damped travel curves, the piezoelectrically actuated fast mechanical switch is better suited for sequential submodule operations to reduce the interruption time, the peak current and the fault energy to be absorbed in hybrid circuit breakers. [ABSTRACT FROM AUTHOR]

Nowadays, the dc microgrid is getting much more attention due to its numerous advantages. However, accurate and timely detection of a fault and its location is still challenging. This article proposes a fast and effective fault identification and localization scheme for dc microgrids. This article implements the dc component concept to detect and locate the fault. The sliding discrete Fourier transform technique is used for the computation of dc components. At the first stage, the fault is identified by noticing the change in the direction of both the end current signals. In the second stage, the fault point resistance is estimated. Finally, in the third stage, the location of the fault is determined. The proposed methodology is implemented in real-time on the LabVIEW platform. The testing is performed for different types of faults at various fault locations considering distant topologies of the dc microgrid. [ABSTRACT FROM AUTHOR]

DC circuit breaker is the key equipment to deal with the interruption of short-circuit current. Compared with the mechanical switch, the solid circuit breaker and the hybrid circuit breaker using the semiconductor device to interrupt the short-circuit current exhibit superiorities in response duration and arc-less characteristics. Massive power devices controlled by corresponding gate drivers which make the semiconductors-based dc circuit breaker bulky and costly are required to withstand the high dc-bus voltage. In this article, the master−slave concept based modular circuit breaker is proposed to simplify the gate driver topology. Only one single gate driver is required to control highly compact modular submodules consisting of power devices, passive components, and diodes. Moreover, the proposed topology can be easily implemented with high flexibility and low cost. Specifically, the gate control function and voltage equalization for series-connected devices can be realized reliably. The master−slave concept and operation principle of the proposed topology are elaborated and the effectiveness has been demonstrated by both simulation and experimental test. [ABSTRACT FROM AUTHOR]

High-voltage direct current (HVDC) circuit breaker development and deployment strongly depend on the testing process, which ensures that the HVDC circuit breakers will satisfy design requirements. This article presents an HVDC circuit breaker test bench circuit configuration that can provide controllable large output currents to simulate different fault conditions for the current breaking test and high output voltage for the dielectric withstand test. The current breaking test circuit is based on multiple cascaded power converters connected in parallel to provide the necessary output current capability. Each cascaded power converter is composed of multiple cells that are operated by a phase-shifted pulsewidth-modulated signal for greater controllability and higher quality of the output waveform. The dielectric withstand test circuit is a simple high-voltage source with a low power rating that can also be used to charge the test bench and the internal circuitry of the circuit breaker that is to be tested. The proposed test bench ensures that fault conditions can be replicated accurately and offers greater flexibility by being able to test mechanical, semiconductor-based, or hybrid HVDC circuit breakers with different current and voltage ratings on the same hardware without any changes. The idea and the operating principle of the proposed test bench are verified experimentally on a downscaled system that consists of three cascaded power converters connected in parallel with three cells per cascaded power converter and with a total equivalent switching frequency of 92.5 kHz. [ABSTRACT FROM AUTHOR]

With the rapid development of DC systems and the increasing demand for DC circuit breakers, electromagnetic repulsive drive-based Thomson coil actuators (TCAs) are widely investigated to provide high-speed actuating required for ultra-fast mechanical switches, especially used in hybrid DC circuit breakers. The actuating mechanism is required to be fast, reliable, and economic. This also creates the need to perform fast highly accurate modeling, simulation, and optimization to investigate the operating mechanism performance. In this study, the fast-operating mechanism-based Thomson coil repulsive drive actuator modeling is investigated. Two simulation methods, equivalent-circuit method (ECM), and finite element method (FEM) are performed for analyzing the TCA performance. In the ECM simulation, Newton's equation of motion is solved together with the circuit equations of the coils. On the other hand, the electrical, magnetic, and mechanical coupling is solved by FEM simulation. A sliding mesh technique is introduced to reduce the computational cost. The two developed solutions were then compared with the experiment for model verification. Results showed that the presented mesh technique was able to significantly reduce the simulation time, and results were in good agreement with the experiment compared to ECM. [ABSTRACT FROM AUTHOR]

DC circuit breakers (DCCBs) are the critical equipment to isolate faults in high-voltage DC grids. The improvement of interruption performances of capacitor-based DCCBs (C-DCCBs) has been widely researched. However, in previous papers, the adaptive reclosing of C-DCCBs is less considered and requires further research. In this paper, a novel C-DCCB with adaptive reclosing ability is proposed. The interruption and adaptive reclosing processes of the proposed C-DCCB are presented. The fault current is interrupted by charging the internal capacitor to a voltage higher than the system voltage. The fault property identification is key to adaptive reclosing and is achieved using the capacitor discharge characteristic. The parameter designs are analyzed to guarantee successful interruptions, and the identification criteria are proposed to serve the adaptive reclosing. On the one hand, the proposed C-DCCB has good interruption performances; on the other hand, an adaptive reclosing strategy is designed for the proposed C-DCCB to restore the power transmission whereas avoiding a second fault shock, which is the main contribution of this paper. Finally, the interruption and adaptive reclosing performances of the proposed C-DCCB are validated using PSCAD/EMTDC simulations.

The modern DC grid is predominantly inductive due to several factors, including line inductance, and the use of current-limiting inductors to control fault current rising rates. These network inductances store a significant amount of energy during regular operation, which is either dissipated or freewheeled to ensure safe current breaking. This research article proposed a highly efficient bidirectional DC circuit breaker topology that not only provides safe current breaking but also effectively recovers the post-current breaking energy from the network's inductance instead of dissipation. An extensive simulation investigation is performed in PSIM software to test the breaker capability for a 400V/400A DC system and the laboratory-scale 48V/1A experimental setup has been developed and employed for further validation purposes. • Modern DC grids have large system inductance which stores significant energy during normal operation. • Developed a bidirectional DCCB topology with regenerative current breaking capability. • Provide efficient current breaking in highly inductive DC network. • Enhancing efficiency and safety of the DC grids by harnessing the energy stored in inductive components. [ABSTRACT FROM AUTHOR]

This paper presents a demonstration of the system identification theory applied to the estimation of Cassie and Mayr arc models' parameters. The purpose of this work is to present a process that allows to estimate the arc model parameters and verify its performances in the representation of a DC short-circuit in a railway system protected by a high-speed circuit breaker. The results show that the arc models can describe the relationship between the arc and the electrical circuit with good precision, but their generalization capacity is limited. [ABSTRACT FROM AUTHOR]

In conventional medium-voltage solid-state circuit breakers (SSCBs), series-connected semiconductor switches are used with metal oxide varistors (MOVs) in parallel with each of them to extend the voltage ratings of the breakers without incurring the dynamic voltage unbalance. Besides, for isolating the faults at faster speeds, the clamped surge voltages of the MOVs are always much higher than the system voltages. For those reasons, the voltage ratings of all the switches in the SSCBs have to be overdesigned according to the surge voltage values, which causes high material costs along with nonideal conduction losses in the SSCBs employed for medium-voltage dc distribution systems. To solve this dilemma, a surgeless diode-clamped multilevel SSCB is proposed in this article. It offers an ultrafast isolation speed with no significant surge voltages or dynamic unbalanced voltage across the semiconductor switches. With these attributes, the proposed SSCB can potentially use the semiconductor switches rated at lower voltages compared to conventional SSCBs and have higher efficiency along with faster isolation speed. The simulation and experimental results are presented to validate the technical feasibility and practical values of the proposed SSCB. [ABSTRACT FROM AUTHOR]