Power-system protection

About: Power-system protection is a research topic. Over the lifetime, 6353 publications have been published within this topic receiving 117961 citations.

Neural network approach to fault detection in electric power systems

Abstract: This paper describes a fault detector that uses artificial neural networks (ANN). It represents the first step to the development of a neural distance relay for protecting transmission lines. We envisage the fault detection problem as a pattern classification process. Our suggested approach is based on the fact that when a fault occurs, a change in the system impedance takes place and, as a consequence, the current phase and amplitude change. The ANN-based fault detector is trained to detect this changes as indicators of the instant of fault inception. Results showing the performance of the fault detector are presented in the paper, indicating that it is fast, robust and accurate.

Some improvements in the three-phase differential equation algorithm for fast transmission line protection

Abstract: This paper presents some improvements of the differential equation algorithm for transmission line protection. The improvements are: fault classification; new filtering; and a new algorithm for three-phase faults. Simulation results indicate a nominal operation time of 5-7 ms for three-phase faults and slightly higher for other fault types.

Protection System Modelling in a Probabilistic Assessment of Transient Stability

Abstract: The application of probability methods in the evaluation of power system transient stability has been demonstrated in recent papers1-3. A probabilistic index for transient stability was developed which in addition to considering the random variations in the operating conditions, included the probabilistic aspects associated with the type, location and clearance of the system faults. It was realized during these studies that there was a need to develop stochastic models for the protection system behaviour which include the actual design aspects. The operational behaviour of the protection system is an important component in the high degree of security and service continuity associated with bulk power systems. This paper illustrates an approach used to model the protection system in the probabilistic assessment of transient stability. The probability density functions of the operating times associated with the components of the protection system such as relays, breakers, etc. are used in conjunction with the reliabilities of the main and back-up protection schemes to obtain the probability density functions of the fault clearing time for different fault locations. These density functions are used together with the critical fault clearing time for a given fault type and location to obtain a probabilities index for transient stability. A simple distance impedance protection system is used to illustrate the procedure. Continuous as well as discrete density functions for the operating times of the protection system components are used. This paper illustrates the basic probabilistic nature of the fault clearing phenomenon and its importance in transient stability assessment.

A hybrid algorithm for high speed transmission line protection

Abstract: A common method used in UHV transmission line protection is based on impedance measurement technique. The fault detection speed of impedance protection schemes cannot be improved without sacrificing the relay reach limit. Protection algorithms based on fault generated transient signals have shown promising results in improving the speed, but these methods have inherent reliability problems. This paper examines how the fault generated transient information can be used to achieve fast fault detection speeds in a distance protection scheme while maintaining a high reliability level.