基于磁通门原理的保护用电流互感器残留剩磁快速在线检测和消除方法研究

Protection current transformer (CT) is one of the most important equipment in a power system. The problem of CT saturation significantly affect the performance of power system protection, and cause relays mal-operation. The remanent flux is the most important reason causing CT saturation. This project tries to solve the problems of remanent flux measurement and elimination fast and in situ. The research includes: ①Studying the feasibility of the fluxgate theory on iron-core remanent flux measurement, proposing the CT remanent flux measurement method based on the fluxgate theory, and analyzing the impact of the operation of CT remanent flux measurement on the performance of power system protection; ②Studying the dynamic response of CT excited by biased high-frequency square-wave voltage, proposing the CT remanent flux elimination method based on biased high frequency square wave voltage excitation, and analyzing the impact of the operation of CT remanent flux elimination on the performance of power system protection; ③Studying the optimal design of high-frequency square-wave voltage source, proposing the control method of the power electronic convertor and analyzing its dynamic response, and analyzing the impact of stray parameters on the performance of the proposed CT remanent flux measurement and elimination methods; ④Building the experimental prototype of the proposed CT remanent flux measurement and elimination methods and verify the performance of the proposed methods. The achievements of this research can not only reduce the probability of CT saturation occurrence, and then avoid relays mal-operation due to CT saturation, but also lay the foundation of remanent flux measurement and elimination for other equipment with iron-core.

保护用电流互感器（CT）是电力系统的重要设备之一，其饱和问题严重影响了电力系统保护的性能，会导致继电器误动或拒动。铁芯残留剩磁是导致CT饱和的重要诱因之一。本项目将进行CT残留剩磁快速在线检测与消除的研究，主要包括：①研究磁通门原理在铁芯剩磁检测的适用性，提出基于磁通门原理的CT剩磁快速在线检测方法，以及剩磁检测操作对各类保护的影响分析；②研究含偏置高频方波激励状态下的CT动态响应，提出基于含偏置高频方波电压激励的CT残留剩磁快速在线消除方法，以及剩磁消除操作对各类保护的影响分析；③设计最佳的高频方波电压源并研究其控制方法，分析其动态响应和寄生参数对剩磁检测与剩磁消除方法的影响；④研制CT残留剩磁在线检测与消除装置并通过实验验证其性能。本项目成果不但有助于减少CT饱和的概率，进而减少继电器因CT饱和而产生的误动或拒动，而且可以为其他含铁芯的电力设备消磁奠定理论基础。

保护用电流互感器（CT）是电力系统的重要设备之一，其饱和问题严重影响了电力系统保护的性能，会导致继电器误动或拒动。铁芯残留剩磁是导致CT饱和的重要诱因之一。本项目首先提出了基于磁通门原理的CT残留剩磁检测方法，在CT二次侧以高频交流电压激励，通过检测电阻的电压的二倍频幅值来检测剩磁；然后，分别提出了两种保护用CT的残留剩磁消除方法，第一种方法是不基于剩磁的检测而直接消除，另一种方法是在剩磁提前检测后利用高频激励来消除剩磁，两种方法均可以快速有效的消除保护用CT的残留剩磁；接下来，设计了高频交流电压源，并进行了硬件实验。研究结果表明，基于磁通门原理的残留剩磁检测方法能够快速有效的检测保护用CT的残留剩磁，基于含偏置高频交流电压激励的残留剩磁消除方法能够快速有效的消除保护用CT的残留剩磁，进而大幅度减少了保护用CT饱和发生的概率。