CAJ | 학술논문

电流互感器(current transformer，CT)的饱和特性对继电保护的动作性能会产生重要影响。地磁感应电流(geomagnetically induced current，GIC)在区域电网中具有高幅值、低频率、时变性等特点，它对CT饱和特性的影响与外部故障的穿越性电流、涌流中的非周期分量、高压直流输电引起的直流偏磁都不完全相同，值得引起人们的重视。根据 GIC 的典型波形特征构建 GIC 等效源模型，在PSCAD/EMTDC中对GIC作用下的CT饱和特性进行了仿真分析，并研究了与其相关的变压器差动保护受到的影响。研究结果表明，GIC可能导致CT的严重饱和，使CT二次侧电流的波形畸变特征消失，导致变压器差动保护计算出的不平衡电流增大，且差流中二次谐波含量很低，造成差动保护误动。针对该误动情况，可采用基于差流及其二次谐波含量趋势的措施来进行防范。
전류호감기(current transformer，CT)적포화특성대계전보호적동작성능회산생중요영향。지자감응전류(geomagnetically induced current，GIC)재구역전망중구유고폭치、저빈솔、시변성등특점，타대CT포화특성적영향여외부고장적천월성전류、용류중적비주기분량、고압직류수전인기적직류편자도불완전상동，치득인기인문적중시。근거 GIC 적전형파형특정구건 GIC 등효원모형，재PSCAD/EMTDC중대GIC작용하적CT포화특성진행료방진분석，병연구료여기상관적변압기차동보호수도적영향。연구결과표명，GIC가능도치CT적엄중포화，사CT이차측전류적파형기변특정소실，도치변압기차동보호계산출적불평형전류증대，차차류중이차해파함량흔저，조성차동보호오동。침대해오동정황，가채용기우차류급기이차해파함량추세적조시래진행방범。
There is a close relation between the saturation characteristic of current transformer (CT) and the performance of protective relayings. In regional power grid the geomagnetically induced current (GIC) possesses the feature of high-amplitude, low-frequency, time-variance and so on, its impact on saturation characteristic of CT is not so identical with the impacts of through-current due to external fault, non-periodic component in inrush current and DC magnetic biasing caused by HVDC power transmission, so it is worthy of attention. Based on typical waveform feature of GIC an equivalent source model of GIC is constructed, and using PSCAD/EMTDC the saturation characteristic of CT under the affect of GIC is simulated, and the resulting affect on transformer differential protection is researched. Research result shows that GIC may lead to serious saturation of CT’s magnetic path and it makes the waveform distortion characteristic in the current at CT’s secondary side disappeared, so the unbalanced current calculated by transformer differential protection is enlarged and the content of the second order harmonic in the differential current will drop below the restraint threshold, and finally the malfunction of transformer differential protection occurs. To prevent such a malfunction, the measure based on differential current and the variation tendency of the content of second order harmonic in it can be adopted.