电磁式电流互感器的GIC直流偏磁谐波分析

Abstract

地磁感应电流(GIC)和运行于单极–大地回路方式的高压直流输电系统会使电力系统中的电磁式电流互感器(TA)产生直流偏磁效应，可能引起计量装置的误差和继电保护装置误动。本文分析了在GIC作用下，电流互感器的直流偏磁的产生机理，并应用PSCAD/EMTDC软件，基于电流互感器的Jiles-Atherton模型，建立了交流系统中电流互感器的直流偏磁的等效分析电路并进行仿真，研究分析了不同大小的GIC入侵电流互感器一次绕组，励磁电流畸变程度及谐波分布关系，以及电流互感器线圈变比对饱和程度的影响。 Geomagnetic induced current (GIC) and the High Voltage Direct Current (HVDC) systems under mono-polar operation may lead to DC bias of current transformers (CT), which may have an effect on transferring characteristics of CT and result in the mal-operation of metering devices and transformer differential protection. This paper analyzes the generation mechanism of DC bias of CT caused by GIC, and an equivalent analysis model for CT in the AC power system is established based on Jiles-Atherton model in PSCAD/EMTDC. This article also analyzes the distortion levels of the exciting current and its harmonics under the condition of DC bias induced by different amplitudes of GIC, and how CT ratios have effect on its saturation is discussed as well.