On reliability and performance analyses of IEC 61850 for digital SAS

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Toward a substation automation system based on IEC 61850

With the global trend to digitalize substation automation systems, International Electro technical Commission 61850, a communication protocol defined by the International Electrotechnical Commission, has been given much attention to ensure consistent communication and integration of substation high-voltage primary plant assets such as instrument transformers, circuit breakers and power transformers with various intelligent electronic devices into a hierarchical level. Along with this transition, equipment of primary plants in the switchyard, such as non-conventional instrument transformers, and a secondary system including merging units are expected to play critical roles due to their fast-transient response over a wide bandwidth. While a non-conventional instrument transformer has advantages when compared with the conventional one, extensive and detailed performance investigation and feasibility studies are still required for its full implementation at a large scale within utilities, industries, smart grids and digital substations. This paper is taking one step forward with respect to this aim by employing an optimized network engineering tool to evaluate the performance of an Ethernet-based network and to validate the overall process bus design requirement of a high-voltage non-conventional instrument transformer. Furthermore, the impact of communication delay on the substation automation system during peak traffic is investigated through a detailed simulation analysis. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

ICT Technologies, Standards and Protocols for Active Distribution Network Automation and Management

The concept of active distribution network (ADN) is evolved to address the high penetration of renewables in the distribution network. To leverage the benefits of ADN, effective communication and information technology is required. Various communication standards to facilitate standard-based communication in distribution network have been proposed in literature. This chapter presents various communication standards and technologies that can be employed in ADN. Among various communication standards, IEC 61850 standard has emerged as the de facto standard for power utility automation. IEC 61850-based information modeling for ADN entities has also been presented in this chapter. To evaluate the performance of ADN communication architecture, performance metrics and performance evaluation tools have also been presented in this chapter

Automation, Protection and Control of Substation Based on IEC 61850

Reliability of power system protection system has been a key issue in the substation operation due to the use of multi-vendor equipment of proprietary features, environmental issues, and complex fault diagnosis. Failure to address these issues could have a significant effect on the performance of the entire electricity grid. With the introduction of IEC 61850 standard, substation automation system (SAS) has significantly altered the scenario in utilities and industries as indicated in this thesis

Performance analysis of transformer differential protection (87T) based on sampled values

Orientador: Prof. Dr. André Augusto MarianoCoorientador: Prof. Dr. Mateus Duarte TeixeiraDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Elétrica. Defesa : Curitiba, 27/07/2023Inclui referênciasResumo: A norma IEC 61850 e o barramento de processos se tornaram o padrão para sistemas de automação em subestações no mundo todo, redefinindo como os Sistemas de Proteção, Controle e Automação (PACS) são projetados. A aplicação do barramento de processos representa a utilização de merging units como um elemento de digitalização entre equipamentos primários e relés de proteção. Este novo componente no sistema de proteção pode introduzir tempo adicional para eliminação de faltas na cadeia de proteção. Para esta dissertação, o objetivo é analisar o impacto destas alterações na cadeia de proteção. Foi utilizado um ambiente de testes para avaliar uma proteção de transformador em uma condição tal que permitisse quantificar o desempenho do transformador em cenários específicos: i) diferentes topologias de merging units, com uma ou duas merging units publicando SV streams, mais uma condição com uma simulação híbrida, com um enrolamento de transformador medido digitalmente e outro convencionalmente; ii) com streams de sampled values considerando um ou dois ASDUs, como especificado nas normas IEC 61850-9-2LE e IEC 61869-9 respectivamente; iii) O volume de tráfego de rede, levando em conta o uso de VLANs para limitar as mensagens que são entregues as portas ethernet do IED de proteção, variando de todas as mensagens publicadas na rede, para apenas as necessárias, mais um caso adicional onde todos os dispositivos desnecessários foram desconectados. Todos os testes foram realizados com um relé de proteção adicional conectado em paralelo com o digital, para gerar os resultados exatos necessários para comparar aplicações digitais e convencionais. Para todos os casos de teste, uma mala de testes foi utilizada para gerar a falta diferencial trifásica. Os resultados dos testes identificaram um desempenho melhor para topologias híbridas ou com duas MUs do que com uma MU. A aplicação medida com uma ASDU encontrou tempos de trip mais rápidos do que com duas ASDU. A comparação relacionada a tráfego de dados confirma seu impacto no desempenho da proteção, onde uma rede com tráfego leve apresentou resultados melhore que em testes com volume maior. Finalmente, a comparação geral entre todos os testes com proteção com barramento de processos e convencional resultaram em resultados levemente mais rápidos para a proteção convencional. Ainda, todos os testes realizados com merging units atenderam as normas referidas para desempenho de proteção, bem como todos os resultados estão alinhados com aqueles apresentados nas publicações utilizadas como referência.Abstract: IEC 61850 and process bus have become the standard for substation automation systems worldwide, redefining how Protection, Automation, and Control Systems (PACS) are designed. The application of process bus represents introducing merging units as the digitization element between the primary switchgear and protection relays. Such new component in the protection system can induce additional time in the overall protection chain for fault clearance. For this dissertation, the objective is to analyze the impact of such changes in the protection chain. A test environment was utilized to evaluate a transformer protection in such a condition that allowed to quantify its performance for certain scenarios: i) different merging unit topologies, with either one or two MUs publishing SV streams, plus another condition with a hybrid simulation, with one transformer winding digitally measured and another conventional one; ii) with sampled values streams considering one or two ASDUs, as present on IEC 61850-9-2LE and IEC 61869-9 respectively; iii) The network traffic load, by taking into account the usage of VLANs to limit the data that is delivered to the ethernet ports of the protection IED, ranging from all the published messages in the network, to just the necessary ones, plus an additional case where all unnecessary devices were disconnected. All tests were performed with a conventional protection relay connected in parallel to the digitized one, to generate the exact results necessary to compare digital and conventional applications. For all test cases, a relay test set was used to generate a three-phase differential fault. Test results have identified better performance for topologies with hybrid or two MUs then with one MU. The measured application with one ASDU had faster trip times then the one with two ASDU. The comparison related to network traffic shows the impact of it on protection performance, where a light network traffic load resulted on better results than the tests with more load. Finally, the overall comparison between all tests with process bus and conventional protection give the conventional protection a slight better overall result. Still, all test results with merging units have complied with the referred standards for protection performance, as well as the results are aligned with those found on reference papers

Investigating Performance and Reliability of Process Bus Networks for Digital Protective Relaying

To reduce the cost of complex and long copper wiring, as well as to achieve flexibility in signal communications, IEC 61850 part 9-2 proposes a process bus communication network between process level switchyard equipments, and bay level protection and control (P&C) Intelligent Electronic Devices (IEDs). After successful implementation of Ethernet networks for IEC 61850 standard part 8-1 (station bus) at several substations worldwide, major manufacturers are currently working on the development of interoperable products for the IEC 61850-9-2 based process bus. The major technical challenges for applying Ethernet networks at process level include: 1) the performance of time critical messages for protection applications; 2) impacts of process bus Ethernet networks on the reliability of substation protection systems. This work starts with the performance analysis in terms of time critical Sampled Value (SV) messages loss and/or delay over the IEC 61850-9-2 process bus networks of a typical substation. Unlike GOOSE, the SV message is not repeated several times, and therefore, there is no assurance that each SV message will be received from the process bus network at protection IEDs. Therefore, the detailed modeling of IEC 61850 based substation protection devices, communication protocols, and packet format is carried out using an industry-trusted simulation tool OPNET, to study and quantify number of SV loss and delay over the process bus. The impact of SV loss/delay on digital substation protection systems is evident, and recognized by several manufacturers. Therefore, a sample value estimation algorithm is developed in order to enhance the performance of digital substation protection functions by estimating the lost and delayed sampled values. The error of estimation is evaluated in detail considering several scenarios of power system relaying. The work is further carried out to investigate the possible impact of SV loss/delay on protection functions, and test the proposed SV estimation algorithm using the hardware setup. Therefore, a state-of-the-art process bus laboratory with the protection IEDs and merging unit playback simulator using industrial computers on the QNX hard-real-time platform, is developed for a typical IEC 61850-9-2 based process bus network. Moreover, the proposed SV estimation algorithm is implemented as a part of bus differential and transmission line distance protection IEDs, and it is tested using the developed experimental setup for various SV loss/delay scenarios and power system fault conditions. In addition to the performance analysis, this work also focuses on the reliability aspects of protection systems with process bus communication network. To study the impact of process bus communication on reliability indices of a substation protection function, the detailed reliability modeling and analysis is carried out for a typical substation layout. First of all, reliability analysis is done using Reliability Block Diagrams (RBD) considering various practical process bus architectures, as well as, time synchronization techniques. After obtaining important failure rates from the RBD, an extended Markov model is proposed to analyze the reliability indices of protection systems, such as, protection unavailability, abnormal unavailability, and loss of security. It is shown with the proposed Markov model that the implementation of sampled value estimation improves the reliability indices of a protection system

Secure Control and Operation of Energy Cyber-Physical Systems Through Intelligent Agents

The operation of the smart grid is expected to be heavily reliant on microprocessor-based control. Thus, there is a strong need for interoperability standards to address the heterogeneous nature of the data in the smart grid. In this research, we analyzed in detail the security threats of the Generic Object Oriented Substation Events (GOOSE) and Sampled Measured Values (SMV) protocol mappings of the IEC 61850 data modeling standard, which is the most widely industry-accepted standard for power system automation and control. We found that there is a strong need for security solutions that are capable of defending the grid against cyber-attacks, minimizing the damage in case a cyber-incident occurs, and restoring services within minimal time. To address these risks, we focused on correlating cyber security algorithms with physical characteristics of the power system by developing intelligent agents that use this knowledge as an important second line of defense in detecting malicious activity. This will complement the cyber security methods, including encryption and authentication. Firstly, we developed a physical-model-checking algorithm, which uses artificial neural networks to identify switching-related attacks on power systems based on load flow characteristics. Secondly, the feasibility of using neural network forecasters to detect spoofed sampled values was investigated. We showed that although such forecasters have high spoofed-data-detection accuracy, they are prone to the accumulation of forecasting error. In this research, we proposed an algorithm to detect the accumulation of the forecasting error based on lightweight statistical indicators. The effectiveness of the proposed algorithms was experimentally verified on the Smart Grid testbed at FIU. The test results showed that the proposed techniques have a minimal detection latency, in the range of microseconds. Also, in this research we developed a network-in-the-loop co-simulation platform that seamlessly integrates the components of the smart grid together, especially since they are governed by different regulations and owned by different entities. Power system simulation software, microcontrollers, and a real communication infrastructure were combined together to provide a cohesive smart grid platform. A data-centric communication scheme was selected to provide an interoperability layer between multi-vendor devices, software packages, and to bridge different protocols together

Advanced Communication and Control Methods for Future Smartgrids

Proliferation of distributed generation and the increased ability to monitor different parts of the electrical grid offer unprecedented opportunities for consumers and grid operators. Energy can be generated near the consumption points, which decreases transmission burdens and novel control schemes can be utilized to operate the grid closer to its limits. In other words, the same infrastructure can be used at higher capacities thanks to increased efficiency. Also, new players are integrated into this grid such as smart meters with local control capabilities, electric vehicles that can act as mobile storage devices, and smart inverters that can provide auxiliary support. To achieve stable and safe operation, it is necessary to observe and coordinate all of these components in the smartgrid

Advancements in Real-Time Simulation of Power and Energy Systems

Modern power and energy systems are characterized by the wide integration of distributed generation, storage and electric vehicles, adoption of ICT solutions, and interconnection of different energy carriers and consumer engagement, posing new challenges and creating new opportunities. Advanced testing and validation methods are needed to efficiently validate power equipment and controls in the contemporary complex environment and support the transition to a cleaner and sustainable energy system. Real-time hardware-in-the-loop (HIL) simulation has proven to be an effective method for validating and de-risking power system equipment in highly realistic, flexible, and repeatable conditions. Controller hardware-in-the-loop (CHIL) and power hardware-in-the-loop (PHIL) are the two main HIL simulation methods used in industry and academia that contribute to system-level testing enhancement by exploiting the flexibility of digital simulations in testing actual controllers and power equipment. This book addresses recent advances in real-time HIL simulation in several domains (also in new and promising areas), including technique improvements to promote its wider use. It is composed of 14 papers dealing with advances in HIL testing of power electronic converters, power system protection, modeling for real-time digital simulation, co-simulation, geographically distributed HIL, and multiphysics HIL, among other topics