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This work proposes an interfacing technique that uses the built-in three-phase transmission line models available in simulation platforms to perform Root Mean Square (RMS)- Electromagnetic Transient (EMT) real-time, multi-domain and multi-rate co-simulation. The main objective of this paper is to show the application of this kind of simulation in hardware-in-the-loop (HIL) testing of protective relays. Two well-known platforms are considered in this work: OPAL-RT with its ePhasorSim tool is used for RMS simulation, and RTDS is used for EMT simulation. However, the proposed technique is sufficiently general to be applied to other real-time simulation platforms that have similar built-in transmission line models. To convert waveforms to phasors, a non-buffered rapid curve fitting method was implemented to attend to real-time constraints. During the testing phase of this research, tests for the HIL were completed using an actual transmission line protection relay. The presented results of tests highlight the benefits of the proposed interfacing technique.

This work proposes the use of a novel faulted phase-selection phasor-based algorithm to solve the high-resistance and weak-infeed fault condition selection problem in existent long compensated transmission lines. The algorithm was originally developed for future half-wavelength lines (3000 km for 50 Hz system or 2500 km for 60 Hz), and was slightly modified and tested in a real 645 km 1000 kV Ultra High Voltage transmission system. The algorithm was implemented in a programmable protective relay and tested using a real-time simulator. A series of tests under extreme conditions (such as high impedance fault and very week infeed system together) were conducted to evaluate the performance and robustness of the proposed algorithm.

The evaluation of protection performance after a generator shutdown is mandatory to assess if all automatic actions resulted in system security and safety to its users. Nowadays, however, the number of digital fault recorders and protection devices with oscillographic functionalities has intensely increased, making traditional manual analysis excessively time consuming. In this context, the contribution of this work is to propose a procedure to automate the evaluation of generating units’ protection, making it possible for the engineers to focus on the most important data. The proposed procedure was evaluated through the development of a prototype designed using the multi-agent paradigm, taking advantage of its main computational benefits. The implemented prototype generated correct assessments for a large set of real disturbances, proving to be a very efficient and accurate tool for assessment and decision support to operators.

This paper presents a study on the performance of phasor-based fault location methods under reduced fault period conditions. Such a scenario can arise in lines equipped with high-speed circuit breakers (CBs) and time-domain protective relays, so that the fault can be eliminated even before it reaches its steady-state. Considering this context, challenging scenarios that may arise during phasor-based fault location procedures are firstly addressed, and then statistical approaches for fault location estimation sample processing are investigated, evaluating their advantages and limitations. Initially, Alternative Transients Program (ATP) fault simulations are carried out to generate realistic fault records, which are played back into actual micro-processed relays equipped with both high-speed time-domain protection functions and phasor-based fault location algorithms. Finally, by means of tests using a Real-Time Digital Simulator (RTDSTM) and an actual Digital Fault Recorder (DFR), different procedures to analyze phasor-based fault location data are assessed. The obtained results show the statistical processing of fault location estimations can improve existing fault location procedures in some cases, but not completely solving the problem if CBs come to be faster than those in the present technology.

In this paper, a novel faulted phase selection algorithm is proposed to be used for distance protection applied to half-wavelength power transmission lines. These lines represent an alternating current solution for very-long point-to-point interconnections as an alternative to HVDC. However, no such lines are currently in operation, and if this type of line is to be constructed, it will require its own protection philosophy because of its peculiar characteristics. This paper shows that the fault selection algorithms used in conventional relays do not work properly when applied to half-wavelength lines. The algorithm proposed herein is initially studied in the steady state and ultimately implemented in a programmable protective relay that is tested using a real-time simulator.

Orientador: Maria Cristina Dias Tavares Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação Resumo: A presente pesquisa tem por objetivo o estudo da proteção de distância para linhas de transmissão de energia de meio comprimento de onda (2500 km para frequência de 60 Hz). Tais linhas não existem até hoje e, no caso de serem construídas no Brasil, precisarão de uma nova filosofia de proteção que permita atingir sensibilidade e seletividade para as possíveis faltas que venham a ocorrer. Na primeira parte da pesquisa foi analisado o desempenho de relés comerciais existentes para proteger uma linha de meia onda. A aplicação foi feita para uma linha teste formada por um conjunto de linhas existentes no sistema elétrico brasileiro que formariam uma linha de um pouco mais de meio comprimento de onda (2600 km) e que seria energizada em vazio. Inicialmente foi analisada a função de distância e, em seguida, funções adicionais do relé foram estudadas de forma a melhorar o desempenho da proteção. Testes com o relé foram realizados através do simulador digital em tempo real (RTDS). Para o desenvolvimento de algoritmos de proteção, implementou-se um método de simulação baseado no uso de quadripolos trifásicos, o que tornou possível trabalhar diretamente em regime permanente, com fasores, possibilitanto a obtenção dos perfis de tensão, corrente e outros parâmetros que dependem destes para os diversos tipos de falta, de forma rápida e com baixo custo computacional. A contribuição fundamental do trabalho foi desenvolver algoritmos de dois componentes fundamentais da proteção de distância, projetados para atender linhas de meia onda, uma vez que tais componentes dos relés convencionais não desempenham as suas funções corretamente. Estes componentes são o seletor do tipo de falta e o cálculo das impedâncias aparentes. Desta forma, uma nova proteção de distância própria para linhas de meio comprimento de onda foi desenvolvida. Alguns testes foram feitos no RTDS usando o algoritmo seletor proposto Abstract: This research aims to study the distance protection for half wavelength transmission lines (HWL) (2500 km for frequency of 60 Hz). These lines have not been built yet, but there is a lack of specific protection that will achieve sensitivity and selectivity for possible faults in these very long lines. In the first part of the research, the performance of existing commercial relays was analyzed for protecting HWL. The application was made for a test system where a set of existing 500~kV transmission lines would form a line a with a little more than half wavelength (2600 km) and would be energized (no-load condition). Initially the distance protection function was analyzed, and then additional relay functions have been studied to improve the protection performance. Relay tests were conducted through the real time digital simulator (RTDS). For the development of protection algorithms, a simulation method based on three-phase two-port network that allows to work directly in steady state was implemented. Voltage and current profiles and other parameters that depend on these for different fault types were promptly obtained with very low computational cost. The main contribution of this research was to develop algorithms of two fundamental distance protection components, designed specifically to attend HWL, in which case such components of conventional relays did not operate properly. These components are the fault type selector and the apparent impedances calculation. Thus, a new distance protection appropriate for HWL was developed. Additionally, the fault selector algorithm was implemented into RTDS and some tests were conducted Doutorado Energia Elétrica Doutor em Engenharia Elétrica