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.

Study of wavelet-based ultra high speed directional transmission line protection

Abstract: A novel wavelet-based directional protection scheme is presented in this paper. Using the theory of wavelet singularity detection as a powerful signal-processing tool, the initial arrival of the traveling wave and its sign can be identified reliably. Characteristics of the proposed directional protection algorithm are analyzed and results of simulation studies are given. The wavelet-based directional protection scheme solves several problems existing in current protective relays and is suitable for use as an ultra high speed UHV/EHV transmission line protective relay.

A novel fuzzy neural network based distance relaying scheme

Abstract: This paper presents a new approach to distance relaying using fuzzy neural network (FNM). The FNN can be viewed either as a fuzzy system, a neural network or fuzzy neural network. The structure is seen as a neural network for training and a fuzzy viewpoint is utilized to gain insight into the system and to simplify the model. The number of rules is determined by the data itself and therefore a smaller number of rules is produced. The network is trained with the backpropagation algorithm. A pruning strategy is applied to eliminate the redundant rules and fuzzification neurons, consequently a compact structure is achieved. The classification and location tasks are accomplished by using different FNN's. Once the fault type is identified by the FNN classifier the selected fault locating FNN estimates the location of the fault accurately. Normalized peaks of fundamental voltage and current waveforms are considered as inputs to all the networks and an additional input derived from the DC component is fed to fault locating networks. The peaks and DC component are extracted from sampled signals by the EKF. Test results show that the new approach provides robust and accurate classification/location of faults for a variety of power system operating conditions even with resistance in the fault path.

Adaptive-neuro-fuzzy inference system approach for transmission line fault classification and location incorporating effects of power swings

Abstract: In the present milieu, changes in regulations and the opening of power markets have manifested in the form of large amount of power transfer across transmission lines with frequent changes in loading conditions based on market price. Since conventional distance relays may consider power swing as a fault, tripping because of such malfunctioning would lead to serious consequences for power system stability. A frequency domain approach for digital relaying of transmission line faults mitigating the adverse effects of power swing on conventional distance relaying is presented. A wavelet-neuro-fuzzy combined approach for fault location is also presented. It is different from conventional algorithms that are based on deterministic computations on a well-defined model for transmission line protection. The wavelet transform captures the dynamic characteristics of fault signals using wavelet multi-resolution analysis (MRA) coefficients. The fuzzy inference system (FIS) and the adaptive-neuro-fuzzy inference system (ANFIS) are both used to extract important features from wavelet MRA coefficients and thereby to reach conclusions regarding fault location. Computer simulations using MATLAB have been conducted for a 300 km, 400 kV line and results indicate that the proposed localisation algorithm is immune to effects of fault inception, angle and distance. The results contained here validate the superiority of the ANFIS approach over the FIS for fault location.

A Current-Based Solution for Transformer Differential Protection. Part I: Problem Statement

Abstract: This paper analyzes the problem of transformer differential protection. First, we review the concept of transformer differential protection. We then analyze magnetizing inrush, overexcitation, and current transformer (CT) saturation phenomena as possible causes of relay misoperation. Finally, we summarize the existing methods for discriminating internal faults from inrush and overexcitation conditions. In Part II of the paper we propose a new approach for transformer differential protection and describe the relay that is based on this approach.

Power System Analysis

Abstract: Sinusoidal Steady State Circuit Concepts. Power System Representation. Transmission Lines. The Power Transformer. The Synchronous Machines. The Power Flow Problem. Operation and Control of Power Systems. Balanced and Unbalanced Faults. Fault Analysis by Computer Methods. Power System Protection. Power System Dynamic Performance. Appendices. Index.