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Electrical utility substations are wired with intelligent electronic devices (IEDs), such as protective relays, power meters, and communication switches. Substation engineers commission these IEDs to assess the appropriate measurements for monitoring, control, power system protection, and communication applications. Like real electrical utility substations, complex electrical substation grid testbeds (ESGTs) need to be assessed for measuring current and voltage signals in monitoring, power system protection, control (synchro check), and communication applications that are limited by small-measurement percentage errors. In the process of setting an ESGT with real-time simulators and IEDs in the loop, protective relays, power meters, and communication devices must be commissioned before running experiments. In this study, an ESGT with IEDs and distributed ledger technology was developed. The ESGT with a real-time simulator and IEDs in the loop was satisfactorily assessed and commissioned. The commissioning and problem-solving tasks of the testbed are described to define a method with flowcharts to assess possible troubleshooting in ESGTs. This method was based on comparing the simulations versus IED measurements for the phase current and voltage magnitudes, three-phase phasor diagrams, breaker states, protective relay times with selectivity coordination at electrical faults, communication data points, and time-stamp sources.

A busca por novas tecnologias para tornar os sistemas de automação de subestações (SAS) mais eficientes é contínua. A norma IEC 61850 têm garantido a melhoria contínua da gestão do sistema de potência em diferentes níveis. A parte 9-2 da norma define o perfil do protocolo Sampled Values (SV) e com ele surge a possibilidade da substituição do método de medição convencional, baseado em cabos de cobre, por uma rede Ethernet chamado de Process Bus (PB). A implementação do PB não depende apenas da mudança da instrumentação convencional do pátio, mas também da adaptação da arquitetura dos dispositivos eletrônicos inteligentes ao novo tipo de entrada de dados. Esta pesquisa tem como objetivo a investigação dos efeitos da implementação do PB sobre o desempenho dos relés de proteção, como, por exemplo, os efeitos sobre a amplitude, o espectro de frequência e defasamento angular dos sinais medidos. Foram apresentados, ainda, os aspectos que devem ser considerados durante o processo de engenharia e de projeto de soluções PB de acordo com o guia de aplicação IEC61850-9-2LE e a norma IEC61869-9. As investigações foram realizadas utilizando uma arquitetura de teste laboratorial composta por um relé convencional de distância e dois relés PB do mesmo modelo. Quanto à sincronização de tempo, os dispositivos foram sincronizados via protocolo IEEE1588 (PTP) para garantir a precisão do tempo necessária. Os estudos de caso realizados incluem a simulação de uma linha de transmissão, sob condição de falta no software ATPDraw, dados coletos em campo, como, a curva de inrush de um transformador de média tensão e os tempos de atuação de uma proteção de distância. A principal contribuição desta pesquisa é, apresentar o efeito de reamostragem do sinal SV, que não é considerado pelas normas de PB, os relés PB apresentam um sinal de entrada deslocado em comparação ao relé convencional o que impacta nas análises e detecção de falhas, principalmente em sistemas mistos. O tempo final de atuação da proteção é aumentado em aproximadamente 9 ms devido ao atraso da rede e o metodo de processamento do relé de PB. Esse atraso precisa ser considerado nos estudos de proteção antes da implementação. Caso contrário, pode resultar em um impacto significativo na coordenação, seletividade e ciclo de vida dos ativos. The pursuit for new technologies to make the substation automation systems (SAS) more efficient is continuous. The IEC 61850 standards have ensured the continuous improvement of the power system management at different levels, the part 9-2 of the standard defines the sampled values protocol’s profile and joint with it the possibility of the replacement of the conventional measurement method by an ethernet-based system called process bus. The implementation of the process bus relies not only on changing the conventional switchyard instrumentation but the adaptation of the intelligent electronic device’s architecture to the new kind of data input. This research focuses on the investigation of the effects of the PB implementation over the protection relays performance such as increasing trip time, measurement, and possible phase shift. This research presents aspects that must be considered through the engineering process and design, considering when using PB according to IEC61850- 9-2LE and IEC61869-9. The investigations were performed using a test architecture composed of a distance conventional relay and two PB relays of the same model, regarding time synchronization, the devices were synchronized via IEEE1588 (PTP) protocol to guarantee the time accuracy needed. The carried-out study cases include simulation of a transmission line under fault using the ATPDraw software, data collected in the field, such as the inrush curve of a medium voltage transformer and the trip times of a line distance protection. The two PB relays presented similar results during the tests. This work has as major contributions, to present the resampling effect of the SV signal that is not considered by the PB standards, the PB relays present a time shift in the input signal compared to the conventional relay, which impacts analysis and failure detection, especially in mixed systems. The final trip time is increased by approximately 9 ms due to network delay, this delay needs to be considered in protection studies before implementation. Otherwise, it can result in a significant impact on the coordination, selectivity, and lifecycle of assets.

This article proposes the optimal coordination problem of protective relays within a hybrid optimisation framework which is presented based on integer coded genetic algorithm (ICGA) and non-linear programming (NLP). The optimal coordination problem of directional overcurrent relays (DOCRs) is implemented while aimed at finding the optimal plug setting multiplier (PSM) and time dial setting (TDS). In this respect, PSM is a function of the current transformer (CT) size and the tap of the relay which is discrete in nature. TDS is a function of the operating time of the relay for different short-circuit currents at different locations of the system. Here, the variables of the problem are decomposed into continuous and discrete variables. The first stage of the problem uses the ICGA to determine the size of CTs considering the permitted tap of relays while the second stage utilises the NLP method to evaluate the feasibility and optimality. The presented framework is then simulated on an 8-bus test system. The obtained results verify the effectiveness and the applicability of the optimisation technique to find the optimal settings of DOCRs.

Adding Power Electronic Interfaced Devices (PEID) generation to grids is an increasing trend because of the concurrent development of better power electronic converters and a greater interest in a better utilisation of energy resources. Small and dispersed energy sources that would previously not be worth introducing into the grid is becoming more and more viable and other potential benefits such as better control of voltage levels and smoothing out load changes also spur this development. But while there are great potential benefits of the controllability of these devices there are also risks when existing protection systems are made for the linear behaviour of traditional synchronous generators. This thesis describes the peculiarities of the short circuit behaviour of PEID generators and how this affects the short circuit energy levels in terms of short circuit current, I2t and incident arc energy. Using simulation, it is shown that in the case of the specific mine grid studied, the incident arc energy increases substantially and that this need to be considered when evaluating installation of PEID generation. Användningen av nätansluten omformardriven generering ökar alltmer i takt med att bättre omformare utvecklas och intresset för ett effektivare nyttjande av energiresurser ökar. Små och utspridda energiresurser som tidigare inte var värda att ta vara på tillgängliggörs alltmer, och fördelar som bättre spänningsreglering och lastutjämning driver på utvecklingen. Men med de fördelar som kommer av omformarnas reglerbarhet så kommer också risker beroende av deras olinjäritet, eftersom existerande skyddssystem är anpassade till det linjära beteendet hos traditionella synkrongeneratorer. Den här avhandlingen behandlar säregenheterna i kortslutningsbeteendet hos effektelektroniska omformare och hur det påverkar kortslutningsenergin i bemärkelsen I2t, händelseenergin vid ljusbågar samt kortslutningsströmmen. Via dynamisk simulering så visas att händelseenergin i vissa fall kan öka avsevärt och att detta behöver övervägas vid installation av omformardriven generering.

The uses of high-temperature superconducting (HTS) cables pose a challenge of power system protection since the impedance of the HTS cable is varied during fault conditions. The protection systems should be designed properly to ensure the reliability and stability of the whole system. This paper presents a fault analysis of the co-axial HTS cable in the mesh system and proposes a coordinated protection system. In the proposed protection system, the main protection is the differential current relay whereas the backup protections are the overcurrent and directional overcurrent relays. The normal and abnormal relay operations are considered to analyze the transient fault current in the HTS cable and evaluate the performance of the proposed coordinated protection system. Characteristics of cable impedances and temperatures under various fault conditions are presented. The proposed protection scheme is validated by the simulation in the PSCAD/EMTDC program. Simulation results show that the coordinated protection scheme could successfully protect the HTS cables in both normal and abnormal relay operations.

The design and real-time hardware-in-the-loop implementation of a hybrid synchrophasors and GOOSE-based automatic synchronization algorithm are presented in this paper. Automatic synchronization is performed by utilizing the synchrophasor measurements from two commercial phasor measurement units (PMUs), while the coordinated control commands to automatic voltage regulator and/or turbine governor control and trip command to the circuit breaker are issued using IEC 61850-8-1 GOOSE messages. The algorithm is deployed inside the PMU using the protection logic equations, and direct communication between the PMUs is established to minimize the communication latencies. In addition, the algorithm is tested using a standard protection relay test-set, and automatic test sequences are executed to validate its performance. It is concluded that the hybrid synchrophasor and GOOSE-based automatic synchronization scheme ensures minimum communication latencies, reduces equipment cost, facilitates interoperability, and performs automatic reconnection adequately.

I detta examensarbete utreds möjligheten att med hjälp av nya smarta elmätare få en ökad inblick i elkvalitén i elnäten samt att ge nätägare möjligheten att automatiskt eller via fjärrsignal koppla bort solcellsanläggningar i de fall de orsakar dålig elkvalité. Motiveringen till studien har varit att en ökad utbyggnad av solcellsanläggningar med tilhörande växelriktare och en trolig framtida ökning av snabbladdare och andra olinjära laster i näten ökar utmaningen för elnätsföretag att klara gällande krav på elkvalité. Samtidigt har utvecklingen av elmätare gjort att de idag har många funktioner som elnätsföretag kan dra nytta av på sätt som tidigare inte varit möjligt. Studien inleddes med en litteratur-studie där information om vad elmätare idag är kapabla till togs fram. Ett praktiskt test genomfördes på en solcellsanläggning där en elmätare installerades och konfigurerades att koppla bort solcellerna vid över-spänning. Studien har visat att smarta elmätare bör kunna användas som ett långsammare, sekundärt skydd som kopplar bort solceller i de fall som växelriktarna brister i sina säkerhetsfunktioner. Elmätarna kommer också kunna ge nätägare en mängd intressant information om elkvalitén. In this thesis the possibility for smart meters to give utility companies an increased knowledge about the power quality in the grid has been investigated. During the investigation the possibility to use smart meters to automatically or by remote control disconnect solar power units in case of poor power quality caused by the production units has also been researched. The motivation to perform the study was that a future increase in distributed generation, rapid chargers for electric vehicles and other non-linear loads will make it harder for utility companies to meet the demands concerning power quality. At the same time electricity meters has developed over time and are today capable of providing grid operators with functions that has not been possible in the past. The first part of the study focused on obtaining information about what smart meters are capable of today through a literary study. A practical test was conducted on a solar power unit where a smart meter was installed and configured to automatically disconnect the solar power unit in case of over voltage. The study has shown that smart meters could be used as a slower, secondary protection that disconnects the solar power units in cases where the solar inverters safety functions fails. The smart meters will also be able to give grid operators a large amount of information about the power quality in the grid.

High Voltage Shunt Capacitor Banks (HV-SCBs) are critical substation assets that are primarily used to improve power factor and thus power transmission capability. Over temperature, over voltages, manufacturing defects can cause internal failures of capacitor elements. With today’s sensitive protection available in numerical relays these failures will be detected and SCBs will be taken out of service. But determining the phase and section in which capacitor elements have failed is important for utilities to decrease downtime of SCBs. This thesis proposes methods to address the challenges in fault location of SCBs. The proposed methods apply calibrating factors that compensate for pre-existing inherent unbalances, and system voltage unbalances. They can mitigate the gradual capacitance change due to temperature effects or natural aging. The presented fault location methods are further enhanced to detect the number of failed elements. The proposed methods can be integrated into common unbalance protection of the multi-functional numerical SCB relays and put forth solutions to condition monitoring of SCBs. Advance maintenance alarms for fuse saving in externally-fused SCBs, and reducing the search space for the faulty cans with fuseless or internally-fused designs are the significant outcomes of the proposed methods. The proposed methods are simulated in a relay modeled in MATLAB and the voltages/currents are played back from COMTRADE records of PSCAD electromagnetics transient simulations. Detecting consecutive failures, ambiguous failures, and delivering the number of failed elements for each alarm in fault reports are valuable to the utility community and have been verified for the proposed methods.

More and more maritime applications as marine vessels and offshore platforms need an adaptive protection power system. However, the adaptive protection is yet to be implemented in the maritime sector. Usually, the adaptive protection implies the existence of a central control unit that monitors the entire electrical network and changes the relay settings accordingly, but this approach is not adequate for the maritime power systems. This paper propose a decentralized adaptive protection method, where each protection relay is able to identify by itself the network status without the need of a central control unit. The new adaptive protection method is based on communication between the overcurrent relays and the equipment that could affect the protection system, such as circuit breakers and generators. Using PSCAD, the proposed method is implemented in a test medium voltage maritime power system that possess some of the characteristics of the maritime applications, as variable generation and network reconfiguration.

The paper present a preliminary study of the protective relays of a 10 MW sized battery energy storage system (BESS) recently installed by TERNA, the Italian TSO. A complete model of the system, including inverters, has been implemented in ATP-EMTP in order to assess the behaviour of protective relays during symmetric and asymmetric faults. Results show that ground fault protection of MV feeders can be performed by zero-sequence non-directional overcurrent relays, obtaining a correct fault selection even for fault resistances in the kΩ range. Phase-to-phase and three-phase fault selection can be performed by means of overcurrent relays: an inverter current limiting control under fault conditions has to be implemented to avoid the system shutdown. Lastly, HV-level faults have been simulated during BESS-supplied, islanded operation, evidencing very low fault current contributions, depending on the actual share of battery modules operating at the time of fault, with less modules giving worst results.

Karmaşık bir yapıya sahip olan elektrik güç sistemlerinin meydana gelen arızalara karşı korunabilmesi için bulanık mantık tabanlı sayısal koruma rölesinin tasarımı ve prototip laboratuar modeli üzerinde gerçekleştirilmesi bu çalışmada incelenmiştir. Laboratuar ortamında bir prototip oluşturulmuş ve sonuçlar elde edilmiştir. Tasarlanan bulanık mantık tabanlı sayısal koruma rölesi çok amaçlı yapıya sahip olup, korumanın yanısıra işletime yönelik karar mekanizması da oluşturulabilmektedir.

Karmaşık bir yapıya sahip olan elektrik güç sistemlerinin meydana gelen arızalara karşı korunabilmesi için bulanık mantık tabanlı sayısal koruma rölesinin tasarımı ve prototip laboratuar modeli üzerinde gerçekleştirilmesi bu çalışmada incelenmiştir. Laboratuar ortamında bir prototip oluşturulmuş ve sonuçlar elde edilmiştir. Tasarlanan bulanık mantık tabanlı sayısal koruma rölesi çok amaçlı yapıya sahip olup, korumanın yanısıra işletime yönelik karar mekanizması da oluşturulabilmektedir.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior This dissertation proposes two methodologies for the phasor estimation on protective relays in Electrical Power Systems. Firstly, a theoretical introduction of signal processing, the structure of a protective relay and phasor estimation algorithms is presented, including some of the algorithms used on the electrical system, as well as the two proposed methodologies. The first one makes use of the concept of curve-fitting, while the other uses Artificial Neural Networks, both with the goal of performing the real-time estimation of the signal amplitude and phase angle. Secondly, it is made a comparative analysis of the two proposed methods with four well-known and currently used algorithms. This comparison is made through the creation of several test signals with different simulation parameters. From these simulations, six performance indexes are used for the quantitative evaluation of each algorithm, from where the most effective method can be determined through the arithmetic mean of these indexes. Lastly, after all the simulation cases have been presented, a summary of the characteristics of each algorithm is made, based in their numerical results. Then, based on the values obtained on each performance index, the strong and weak points are highlighted, as well as the general classification of each method. Essa dissertação propõe duas metodologias para a estimação fasorial em relés de proteção em Sistemas Elétricos de Potência. Primeiramente é apresentada uma introdução teórica ao processamento de sinais, à estrutura do relé de proteção, e aos algoritmos de estimação fasorial propriamente ditos, incluindo alguns dos algoritmos utilizados no sistema elétrico, assim como as duas metodologias propostas. A primeira delas faz uso do conceito de ajuste de curvas, enquanto que a segunda utiliza Redes Neurais Artificiais, ambas com o objetivo de realizar a estimação da amplitude e ângulo de fase de um sinal em tempo real. Em um segundo momento, é feita a análise comparativa dos dois métodos propostos com quatro algoritmos bastante conhecidos e utilizados nos relés numéricos. A comparação é feita através da criação de diversos sinais de teste com diferentes parâmetros de simulação. A partir dessas simulações, são usados seis índices de desempenho para a avaliação quantitativa de cada algoritmo, de onde, a partir da média aritmética destes índices, pode-se determinar o método mais eficaz para cada caso. Por fim, após todos os testes terem sido realizados, com base em seus resultados numéricos, é realizada uma condensação das características de cada algoritmo. Com base nos valores obtidos em cada índice de desempenho, são destacados os pontos fortes e fracos, bem como a classificação geral de cada método.

Com novas normas, incentivos governamentais e preocupação com questões ambientais, é esperado um crescimento no número de unidades de geradoras conectadas a rede a partir dos consumidores. Algumas questões técnicas relacionadas à elevada penetração de geração distribuída nos alimentadores de distribuição preocupam as concessionárias de energia, as quais buscam meios de prevenir possíveis efeitos indesejados no sistema elétrico. Esta pesquisa apresenta o desenvolvimento de um relé digital aplicado à proteção da conexão de geração distribuída na rede elétrica, com foco em microgeração e minigeração proveniente de geradores síncronos, assíncronos e inversores. O relé digital contempla as principais funções de proteção exigidas pelos procedimentos e normas de acesso nacionais, incluindo algoritmos anti-ilhamento. O seu funcionamento se dá pela medição das grandezas elétricas no ponto de conexão entre a geração distribuída e a rede elétrica, filtragem digital dos sinais e processamento dos algoritmos das funções de proteção. Como num relé digital convencional, as funções de proteção podem ser configuradas individualmente, permitindo construção de expressões lógicas e de bloqueio. O protótipo pode ser monitorado e controlado localmente, através de uma aplicação instalada em um computador e utilizando a rede Ethernet. O protótipo permite controle remoto pela concessionária através de uma rede de telecomunicação em malha instalada no sistema elétrico de distribuição, utilizando protocolo ZigBee. É apresentada uma revisão bibliográfica sobre os efeitos e os problemas da geração distribuída no sistema elétrico, contextualizando o futuro das nossas redes de distribuição em relação a situação de países mais desenvolvidos nesse tema. Em seguida, são apresentadas as principais técnicas de processamento digital de sinais para relés digitais e o funcionamento das funções de proteção. Os detalhes do desenvolvimento do hardware, estratégias para filtragem digital e implementação dos algoritmos de proteção são apresentados. Algumas técnicas no algoritmo de filtragem e nas funções de proteção, como a medição de frequência trifásica utilizando a transformada de Clarke, são discutidas e avaliadas. Os resultados dos testes de funcionamento do protótipo, realizados em laboratório, são apresentados. Concluiu-se que o relé digital contempla um conjunto de proteções que abrange as principais normas para o acesso de geração distribuída no Brasil, pode ser utilizado como proteção de retaguarda para sistemas já dotados de proteções internas, como inversores, além de possibilitar o controle remoto de geração distribuída através da rede de telecomunicação em malha com protocolo ZigBee. With new standards, government incentives and concerns about environmental questions, is expected the growth of the number of generating units connected to the grid from consumers. Some technical issues related to the high penetration of distributed generation on distribution feeders concerns the power utilities, which look for solutions to prevent possible unwanted effects on the electrical system. This research presents the development of a digital relay applied to protect the interconnection of distributed generation in the grid, focusing on micro and mini electricity generation plants from synchronous and asynchronous generators, and inverters. The digital relay contains the main protection functions required by PRODIST and utilities standards, including anti-islanding algorithms. Its operation is given by the measurement of electrical parameters at the point between the distributed generation and grid, followed by digital signal filtering and protection algorithms processing. Like a conventional digital relay, the protection functions can be individually configured, it’s possible to build logical and blocking expressions with them. The prototype can be monitored and controlled by a personal computer connected in the same local network. The computer must run an interface program. The prototype allow remote control by the utilities, this communication is done by a mesh network installed along the electric distribution system, using the ZigBee protocol. It’s presented a review about the effects and problems caused in the electrical power system by the distributed generation, giving the context of the future Brazilian distribution network in relation to the actual situation of more experienced countries on distributed generation. Following, it’s presented the main technics of digital signal processing applied to digital relays and operation of the protection functions. So then, the details of the hardware development, digital filtering strategies and the implementation of the protection algorithms are presented. Some technics applied to the filtering algorithms and protection function, as the three-phase frequency measurement using Clarke’s transformation, are discussed and evaluated. The test results of the prototype operation are presented, the tests were done in laboratory. The digital relay contain a set of protection functions that covers the main standards of distributed generation access in Brazil, it’s possible to use as a backup protection for systems with protections embedded, as grid tie inverters, and the possibility of remote control of distributed generation through the mesh network with ZigBee protocol.

Philosophy beginning with the ancient Greeks is literally "a love of wisdom" and deals with the most general issues of reality. The Wikipedia dictionary determines philosophy as a science, which studies everything. Logic and critical analysis are the pillars of philosophic thinking. ‘So, why don’t we use these attributes of philosophy to analyze the situation around relay protection,’ – Dr. Vladimir Gurevich raises this question, and it appears that such analysis may result in counterintuitive findings. Философия ( греч.) – дословно "любовь к мудрости", изучает наиболее общие принципы реальности. Википедия определяет философию, как науку, изучающую все. Логика и критический анализ являются столпами философского мышления. Почему бы не применить эти атрибуты философии к анализу ситуации в релейной защите – задался вопросом канд. техн. наук Владимир Гуревич. Оказалось, что такой анализ может привести к парадоксальным выводам

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217 σ., Η ολοένα αυξανόμενη πολυπλοκότητα των συστημάτων ηλεκτρικής ενέργειας (ΣΗΕ) καθιστά αναγκαία όσο ποτέ άλλοτε τη βελτίωση των υπαρχουσών τεχνικών προστασίας, ελέγχου και μετρήσεων, και την ταυτόχρονη ανάπτυξη νέων καινοτόμων μεθόδων για την αποδοτικότερη λειτουργία τους. Μέχρι πριν από λίγα χρόνια, ο συμπληρωματικός εξοπλισμός προστασίας των ΣΗΕ, όπως οι εντοπιστές σφαλμάτων στις εναέριες γραμμές μεταφοράς και στα υπόγεια καλώδια, δε χρησιμοποιείτο συστηματικά. Τα τελευταία, όμως, χρόνια έχει γίνει ευρέως αποδεκτό ότι η γρήγορη και ακριβής εύρεση της θέσης του σφάλματος επιταχύνει σημαντικά το χρόνο αποκατάστασης των βλαβών στα ΣΗΕ, μειώνει τη διάρκεια των διακοπών της παρεχόμενης ισχύος προς τους καταναλωτές, και γενικά βελτιώνει την αξιοπιστία τους. Αναγνωρίζοντας τη σπουδαιότητα των παραγόντων αυτών για τις εταιρείες ηλεκτρισμού, παρατηρείται μία ολοένα αυξανόμενη ζήτηση για αποτελεσματικές μεθόδους εντοπισμού σφαλμάτων, γεγονός που έχει στρέψει το ενδιαφέρον της επιστημονικής κοινότητας που ασχολείται με την προστασία των ΣΗΕ σ’ αυτή την περιοχή έρευνας. Ο σκοπός αυτής της διατριβής είναι η ανάπτυξη προηγμένων αλγορίθμων εντοπισμού σφαλμάτων σε εναέριες γραμμές μεταφοράς ηλεκτρικής ενέργειας, με χρήση συγχρονισμένων ή μη μετρήσεων στα άκρα τους. Ως κριτήρια απόδοσης των αλγορίθμων, τα οποία τους διαφοροποιούν από τις υπάρχουσες μεθόδους, ορίζονται: α) η ακρίβεια των μετρήσεων, που χρησιμοποιούνται ως δεδομένα εισόδου, β) η εξάλειψη των παραμέτρων που ορίζονται από το χρήστη ή λαμβάνονται από εξωτερικές πηγές (π.χ. H/N προστασίας, SCADA), και οι οποίες μπορούν να εισαγάγουν σημαντικό σφάλμα στην ακρίβεια των παραγόμενων αποτελεσμάτων (π.χ. ηλεκτρικές παράμετροι των γραμμών, μοντέλο της διάταξης σειριακής αντιστάθμισης σε γραμμές με αντιστάθμιση σειράς, τύπος του σφάλματος, ισοδύναμα δίκτυα στα άκρα των γραμμών κτλ.), γ) η ακρίβεια του μοντέλου αναπαράστασης των γραμμών μεταφοράς, π.χ. αν πρόκειται για γραμμές μικρού, μεσαίου ή μεγάλου μήκους, δ) ο περιορισμός των αξιοποιούμενων δεδομένων μέτρησης από κάθε άκρο των γραμμών, ώστε να αποφεύγονται προβλήματα συμφόρησης στα κανάλια επικοινωνίας που χρησιμοποιούνται για τη μεταφορά τους. Με βάση τα παραπάνω κριτήρια, στην παρούσα διατριβή αναπτύσσονται επιτυχώς και παρουσιάζονται λεπτομερώς, καινοτόμοι αλγόριθμοι εντοπισμού σφαλμάτων σε γραμμές μεταφοράς απλού κυκλώματος (με ή χωρίς αντιμετάθεση φάσεων) και διπλού κυκλώματος (με ή χωρίς αντιμετάθεση φάσεων, με ή χωρίς χωρητική αντιστάθμιση σειράς, με χρήση μοντέλου μικρού, μεσαίου και μεγάλου μήκους). Οι προτεινόμενοι αλγόριθμοι επαληθεύονται μέσω λεπτομερών προσομοιώσεων σφαλμάτων από το πρόγραμμα υπολογισμού ταχέων μεταβατικών φαινομένων ATP/EMTP. Επιπλέον, αναπτύσσεται και παρουσιάζεται μια νέα μέθοδος υπολογισμού των φασιθετών των μετρούμενων τάσεων και εντάσεων, που θεωρούνται ως δεδομένα εισόδου στους παραπάνω αλγορίθμους, όταν η συχνότητα του συστήματος μεταβάλλεται., Due to the increasing complexities of modern power systems, improving the existing techniques of protection, control and measurement and developing new innovative ones have got much attention recently. The goal is to enhance the overall power system performance. A few years ago, the supplementary protection equipment such as fault locators has got little consideration compared with the main protection one. Nowadays, it has been widely recognized that prompt and accurate location of faults in power systems can accelerate system restoration, reduce outage time and improve the system reliability. This has led to remarkable investments in research for fault location methodologies, which has attracted the attention of power system protection community. The essential factors behind these new strategies are due to the competitive markets and new deregulation policies, in which the terms such as continuity, dependability and reliability play an important role for electric utilities. This thesis focuses on the development of advanced fault location algorithms for overhead transmission lines with use of two-end synchronized or unsynchronized measurements. The following criteria are established for the purpose of evaluating the proposed algorithms, which differentiate them from the existing ones: a) the accuracy of measurements used as input data, b) the exclusion of user-defined parameters or parameters that can be supplied from external sources (e.g. protective relays, SCADA), which can highly affect the fault location accuracy (e.g. electrical parameters of transmission lines, the compensation device model in series-compensated transmission lines, the fault type, the source impedance at line terminals etc.), c) the accuracy of transmission line models adopted (e.g. short, medium and long lines for phasor domain algorithms), d) the utilization of limited measurement data from both line ends, in order to reduce the burden of communication channels employed to transfer the required data. Based on the above criteria, this thesis presents new accurate fault location algorithms for single-circuit transmission lines (with or without transposition) and double-circuit transmission lines (with or without transposition, with or without series compensation, short/medium/long length line model). The thesis provides extensive evaluation studies of the proposed algorithms with use of reliable ATP/EMTP simulation data of faults applied under various system/fault conditions, at different locations on single/double-circuit transmission lines. Moreover, a practical and precise method is developed for calculating voltage and current phasors in electric power networks, which are used as input data to the proposed fault location algorithms, under frequency variations., Χρήστος Α. Αποστολόπουλος

Orientadores: Walmir de Freitas Filho, José Carlos de Melo Vieira Júnior Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação Resumo: Geradores síncronos conectados em redes de distribuição de energia elétrica estão sujeitos a operarem de forma ilhada após a ocorrência de distúrbios na rede elétrica. Ilhamento ocorre quando uma parte da rede de distribuição torna-se eletricamente isolada da fonte de energia principal (subestação), mas continua a ser energizada por geradores distribuídos conectados no subsistema isolado. A prática atualmente utilizada pelas concessionárias e recomendada nos principais guias técnicos é desconectar todos os geradores tão logo ocorra um ilhamento. Tipicamente, é necessário detectar uma situação de ilhamento em menos de dois segundos, dependendo, principalmente, do tempo de operação dos religadores automáticos. Os métodos mais comuns e baratos para detectar ilhamento compreendem relés baseados em medidas de freqüência (sub/sobrefrequência, taxa de variação de frequência e "salto de vetor") e o relé de tensão. No entanto, esses relés podem falhar se os níveis de desbalanço de potência ativa e reativa no subsistema ilhado forem pequenos. Portanto, o objetivo dessa dissertação é investigar a potencialidade de novos sinais para detectar ilhamento de geradores síncronos distribuídos, como forma de substituição ou complementação aos dispositivos de proteção anti-ilhamento convencionais. Os sinais analisados neste trabalho são taxa de variação da potência ativa (dP/dt), a relação Volts por Hertz (V/Hz), a variação da impedância (Z) medida no ponto de acoplamento comum (PAC), e a diferença angular ('delta' 'teta') entre as tensões medidas no PAC e na subestação. A investigação é baseada no levantamento de um conjunto de curvas relacionando tempo de detecção e desbalanço de potência ativa/reativa e nas zonas de não detecção, as quais fornecem os pontos de operação para os quais o relé em estudo falha na detecção do ilhamento. As curvas e as zonas são obtidas através de simulações de transitórios eletromagnéticos trifásicas considerando diferentes perfis de carga-geração na rede ilhada. Os resultados obtidos mostram que os sinais analisados têm um grande potencial para esse tipo de aplicação, porém são sujeitos à atuação indevida no caso da ocorrência de eventos que não sejam ilhamentos na rede de distribuição. Assim, uma análise de falsa operação também é conduzida e são propostas melhorias para minimizar e/ou eliminar a atuação indevida desses relés aqui investigados Abstract: Synchronous generators connected to distribution power networks are likely to operate islanded following faults clearance in the system. Islanding occurs when a portion of the distribution system becomes electrically isolated from the substation, yet it continues energized by distributed generators connected to the islanded system. Utilities and standards recommend the disconnection of distributed generators immediately after islanding occurrences, otherwise it can lead to a number of problems to the generator and the connected loads. Typically, it is required to detect an islanding situation faster than two seconds after the island formation, depending, mainly, on the operation time of automatic reclosers. The most common and economical methods to detect islanding include the relays based on measures of frequency (under/over frequency, rate of change of frequency and vector surge) and voltage. However, these relays can fail if the active and reactive power imbalance levels in the islanded system are small. Therefore, the objective of this thesis is to investigate the potentiality of new signals to detect islanding of distributed synchronous generators, as replacement or complement to conventional protection anti-islanding devices. The signals analyzed in this research are the rate of change of generator active power (dP/dt), the ratio Volts per Hertz (V/Hz), impedance variation (Z) measured at the point of common coupling (PCC), and the angular difference ('delta' 'teta') between the voltage angle measured at the PCC and at the utility substation. The investigation is based on a set of curves, which relate time of islanding detection and active/reactive power imbalance and on the nondetection zones, which provide the operating points for which the relay fails to detect the islanding. These are obtained through electromagnetic transient three-phase simulations considering different profiles of generation-load in the islanded network. The results show that the signals analyzed have a huge potential for this type of application, however, their performance can decrease in case of occurrence of non-islanding events in the distribution system. Thereby, an analysis of false operation is conducted in order to propose improvements to minimize and/or to eliminate improper behavior of these relays Mestrado Energia Elétrica Mestre em Engenharia Elétrica

Приведено описание и представлены результаты экспериментальных исследований быстродействующего гибридного реле тока с чувствительным органом на герконе. Показано, что такое реле может быть с успехом использовано для ускорения действия основной релейной защиты. Приведено опис і представлення результатів експериментальних досліджень швидкодіючого гібридного реле струму з чутливим органом на герконі. Показано, що такі реле може бути з успіхом застосовано для прискорення дії основного релейного захисту. Specification and results of experimental research on a high-speed hybrid overcurrent relay with a reed switch as the sensitive element are given. It is shown that this relay can be successfully used for acceleration of the basic relay protection action.

It is the author's second publication on nonconformance of parameters of subminiature output relays used in microprocessor-based protective devices to actual operation conditions and standards. The article suggests adjustment of the standards and presents specific engineering solutions to this problem

In this article a methodology for setting up generator out-of-step protective relay, to be applied in any generator of Colombian Power System is presented. A comparison between settings proposed in research articles and a manufacturer was carried out. The application of the methodology required information as generator direct-axis transient reactance, transformer reactance, power system impedance and critical time for setting up protective relay. The proposed methodology for setting up generator out-of-step protective relay was applied in the Salvajina and Alto Anchicayá power plants, improving the selectivity with new settings approaches. En este artículo se presenta una metodología para el ajuste de la protección de pérdida de paso en generadores, que puede ser aplicada en cualquier generador del Sistema de Potencia Colombiano. Se presenta una comparación entre los criterios de ajuste propuestos en artículos de investigación y el de un fabricante. La aplicación metodológica requirió información como la reactancia transitoria de eje directo del generador, la reactancia del transformador y la impedancia del sistema, así como encontrar los tiempos críticos requeridos para un correcto ajuste de la protección. La metodología propuesta fue implementada en las protecciones de las centrales eléctricas de Salvajina y el Alto Anchicayá, mejorando la selectividad con nuevos criterios de ajuste

This paper presents an overview on optimal overcurrent relay coordination in protection system and protective relays. Efforts have been made to include all methods used for the coordination of overcurrent relays. It includes techniques, such as Artificial Intelligence (AI) and Nature Inspire Algorithm (NIA) as well as other conventional methods used for overcurrent protection. A brief mentioned is made about conventional methods while more prominence is given on the application of AI and NIA for the protection of overcurrent relays. This paper presents a set of references of all respective papers related and provides a brief summary of the research work. In addition, the results of these techniques also provided in the respective references.

A synchro-generator and a unijunction transistor oscillator in conjunction with a silicon-controlled rectifier form a detection and relay circuit for voltages appearing across the field of a three-phase alternator generated by negative-phase-sequence currents due to unbalanced conditions. Readings were taken of the times required for operation of the relay for various conditions of unbalance. Statistical studies were made to enable time predictions to be offered. It was concluded that the scheme offers the possibility of faster operation, and hence better protection and system stability, than is possible with existing types. In addition, the scheme will result in no loss of dependability over existing types, and the relay portion offers outstanding ruggedness and sensitivity. M.S.