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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.

This work reports the personal computer implementation of a real-time simulator based on the widely used Electromagnetic Transients Program, version Alternative Transients Program (EMTP-ATP) software for testing protection and control devices. The proposed simulator was implemented on a conventional PC with a GNU/Linux operative system including a real-time kernel. Using foreign models programmed in C, ATP was recompiled with the PortAudio (sound card I/O library) with tools for writing and reading the parallel port. In this way, the sound card was used as a digital-to-analog converter to generate voltage waveform outputs at each simulation time step of the ATP, and the parallel port was used for digital inputs and outputs, resulting in a real-time simulator that can interact with protection and control devices by means of hardware-in-the-loop tests. This work uses the minimum possible hardware requirements to try to implement a real-time simulator. Due to the limitation of two channels, this simulator was used mainly to demonstrate the implementation methodology concept at this stage, this concept could potentially be expanded with more powerful hardware to improve its performance. The performance of the implemented simulator was analyzed through interactions with a real intelligent electronic device (IED). Furthermore, a comparison with the results obtained by means of the well-known real-time digital simulator (RTDS) was presented and discussed.

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.