TCT式并联电抗器控制绕组匝间故障保护方案

基于对晶闸管控制变压器(TCT)式并联电抗器的本体结构和控制绕组匝间短路故障特性分析,提出一种针对其控制绕组匝间故障保护的新方案。该方案综合利用控制绕组匝间故障时网侧零序电压低、补偿绕组零序电流大的特点,采用主判据和辅助判据相结合的方式,主判据采用零序过电流保护元件,采取两段式的整定方式以兼顾匝间故障下保护的灵敏度和容量调节过程中的可靠性;辅助判据由网侧零序高电压闭锁元件构成,并增加闭锁判据,保证TCT式并联电抗器在系统非全相运行、区外不对称故障、电抗器空投、容量调节等暂态过程中保护可靠不误动。基于仿真测试结果确定了所提方案的具体整定方法,并对灵敏度进行了校验,分析计算的结果证明了所提方案的可行性和有效性。

Protection schemes for control winding inter-turn faults of TCT-type shunt reactor

The body structure and control winding inter-turn fault characteristics of TCT(Thyristor-Controlled Transformer)-type shunt reactor are analyzed and a protection scheme of main criterion combined with auxiliary criterion is proposed according to the fault characteristics of low grid-side zero-sequence voltage and large compensation winding zero-sequence current. The main criterion adopts the zero-sequence over-current protection element with two-segment setting mode to guarantee the sensitivity of inter-turn fault protection and the reliability of capacity adjustment. The auxiliary criterion adopts the high grid-side zero-sequence voltage blocking element with additional blocking criterion to guarantee the reliable operation of TCT shunt reactor protection during the transient processes of system incomplete-phase operation, out-zone asymmetric fault, reactor switching and capacity adjustment. Its setting principles are determined based on the simulative and experimental results, its sensitivity is checked, and its feasibility and effectiveness are verified by the analytical and calculative results.