The Study Of Transmission Line Protection Based On Transient Current Polarity Comparison

As the rapid development of power industry, higher requirement is brought forward for the power system security and stabilization, and for the transmission line protection. It is an important issue for relay protection workers on how to utilize new types of technologies to develop new protection principle and methods, and improve the performance of the protection device. Focusing on transmission line, the transmission line protection principle realized by transient signal are studied. It has theory study and also face to practical application, which has great theory study and practical application signification.Analysis on the requirement of line transient current polarity comparison protection, wavelet primary function suited for transient signal protection analysis are presented and utilized to extract transient signal. On the basis of transmission line transient signal mathematical model, modular analysis from decoupling transformation and single-circuit transmission line protection principle based on transient current polarity comparison, the transmission line protection principle of a single bus and parallel lines protection principle based on transient current polarity comparison are presented. Phase selection principle and methods for the protection and protection program overview flow are also presented.Simulations of different fault types, fault situation and a practical line model are preceded in allusion to the transmission line protection principle of a single bus based on transient current polarity comparison which is presented in this paper. Simulations of the parallel lines protection principle based on transient current polarity comparison are also preceded. Results of the simulations proved the correctness of the principle.Transient protection hardware scheme is designed in order to utilize the transmission line protection principle based on transient current polarity comparison which is presented in this paper to engineering practice. The paper studies the design target and design methods for each part of the protection hardware design scheme.