Multifunctional Protection Relays Research Articles

Design and Implementation of Multifunction Relay Based on Microcontroller

The power systems are exposed to many abnormal conditions, so an advanced protection system must be provided to stand up to these challenges. Protection devices evolved continuously with the development of power systems. The accuracy, high response, reliability, and speed of fault detection are required in the operating mode of multi-function protective relays. A Multifunction Relay has been designed and implemented, which consists of three types of relays: over current relay OCR, over/under voltage relay OVR/UVR, and differential relay DFR. The relays OCR, OVR/UVR, and DFR are designed according to the standards IEC 60255, IEEE 1159, and IEEE C37.91, respectively, based on Arduino MEGA. The multi-function relay was implemented to work on a single phase.
 The setting of the multi-function relay configuration done using a new design based on the MATLAB GUI environment. Furthermore, the results obtained after each test appear on it and LCD screen. The multi-function relay which is designed can work as (OCR, OVR/UVR, DFR) in the case of a single-phase source.
 The experiential results show that the proposed multi-function relay is accurate, fast response, reliable, selective, good performance, low cost, and sensitivity when used to protect the power system equipment under different operating conditions.

Design, Modeling and Implementation of Multi-Function Protective Relay with Digital Logic Algorithm

In this paper, three phase transmission power system with three different protective schemes such as over current relay, over and under voltage relay and over and under frequency relay is developed using MATLAB/Simulink toolbox. The protective relay is tested for different operating conditions of the transmission power system such as overload, over and under voltage, over and under frequency conditions. Protective relays are explained with simple flowcharts. We used digital logic algorithm for implementation of protective relay. In this paper, a digital multi-function protective relay was designed and implemented on MATLAB/Simulink. In this study we also explore some current techniques ranging from the use of digital logic algorithms to system protection applications. Mother power system protective relays are digital systems based on digital signal processing of power system voltage and current waveforms.

Scheme for synchronous machine stator turn‐to‐turn protection

This study presents a new protection scheme for turn-to-turn fault protection in the stator windings of synchronous machines. The main difference with other methods is the calculation of voltage of the winding from the phase to ground and neutral to ground voltages, which can be obtained from the monitoring provided by any commercial generator multifunction protection relay. This new method allows the employment of the protection transformers already installed in the protection scheme, simplifying and reducing the cost of the protection function. To validate this new technique, finite element method simulations and numerous tests have been performed in a specially built synchronous generator with taps in one of the stator windings. In this way, several turn-to-turn faults have been created at different fault severity levels.

Adaptive phasor estimation technique during off-nominal frequency for numerical relays

ABSTRACTThe use of digital multifunction protection relays and their proper integration on the power system and smart grid is an important element. However, the performance of digital relays depends on many factors and needs to be carefully evaluated. These factors may be caused by correct operations with less performance or completely incorrect operations. Frequency deviation is one of those factors which results from unbalanced demand load and generation levels. Load characteristics and generation control response to demand load changes will effect on amount and duration of frequency deviations. Frequency decreases when demand load is higher than generation, whereas it increases when load is less than generation. Protection relays are provided with frequency tracking to reduce the effects of frequency deviations on accuracy of relay decisions. In this paper, traditional frequency tracking technique used on protection relays is modified to give a better performance (less Total Vector Error, TVE) during off-nominal frequency variations. The performance of the proposed algorithm is compared with traditional tracking using Least Square Error (LSQ), and Discrete Fourier transform (DFT) algorithm without any tracking, which are investigated in MATLAB environment.

Low-Latency Distance Protective Relay on FPGA

The need for high-speed multi-function protective relays in both traditional transmission systems and the new emerging paradigm of the smart grid is growing. As a widely used protective scheme for transmission lines, a distance relay's high speed and reliable operation to clear faults is essential. This paper proposes a real-time low-latency hardware digital distance protective relay on the field programmable gate array (FPGA). Taking advantage of inherent hard-wired architecture of the FPGA, the proposed hardware distance relay design is paralleled and fully pipelined to achieve low latencies in various relay modules which are developed in textual VHDL language. This low-latency feature allows fast operating and data throughput so that the relay can handle high-frequency sampled data and reach higher computational efficiency. In addition, the parallelism and hardwired architecture of the FPGA makes the design more reliable in computation than the sequential software-based numeric relay. The FPGA-based distance relay can operate on both phasor-based signals and instantaneous signals with 2.09 μs and 0.35 μs latency respectively based on the clock frequency of 100 MHz. The hardware relay is tested in real-time by feeding it with generated faulted current and voltage data for typical faults and the relay response recorded. The results demonstrate the speed and effectiveness of the hardware distance relay.

Global Positioning System Application in Current Phase Comparison of Differential Protection Relay of Power Transmission Line

This study simulates short-circuit current before a power transmission system is integrated into the system, so that the differential protection relays at both ends have current value and that current transducer transforms three-phase current to voltage value. Furthermore, a multi-function protection relay tester was used to obtain voltage waveform. The reference voltage using global positioning system synchronous time was compared with three-phase current waveform at both ends so as to obtain time difference. The current angle of various phases at both ends was calculated to compare whether the current angle difference between various phases at both ends was about 180°. The current phase comparison could be used to determine whether wiring is correct. The primary protection relay can synchronously operate when the line is integrated into the system.

Multi-function protective relay on FPGA

Protective relays play a crucial role in the proper operation of a power system, and the reliable transfer of electrical power. The design and implementation of a multi-function digital protective relay on a single field programmable gate array (FPGA) is discussed in this paper. The multi-function relay monitors the frequency and the voltage of the system. An output trip signal is set whenever the voltage value or the frequency value is outside pre-determined ranges. In addition, the multi-function relay estimates the rate of the frequency change. The FPGA (Xilinx 3030PC84-100) was used in the implementation.

A multifunction protective relay for the cogeneration industry

A multifunction relay that uses advanced digital electronic design to incorporate most (or all) of the required protection functions into one package and thereby significantly reduce the expense is described. User requirements and design considerations are examined. The discrete-Fourier-transform-based digital signal processor is discussed. Interprocessor communication and the host processor are briefly considered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Development Of A Neural Network-based Multi-function Protection Relay

The protection of DC traction circuits from fault conditions is a difficult task. The paper describes the development of a neural network to be used in a multifunction protection relay. The neural network developed can discriminate between normal train operation and short-circuit conditions on the DC traction supply. The neural network provides fault protection and location. The neural network was trained and tested using both simulated and actual data. The paper presents results showing that the neural network can discriminate between faults on a DC traction system and the normal operation of both camshaft and chopper controlled rolling stock. Conclusions are given on the advantages and disadvantages of using neural networks, along with their possible use in also locating a fault.