STATCOM不对称控制策略下线路距离保护测量阻抗的改进算法

摘要

Unbalanced control strategy can ensure the safety of static synchronous compensator (STATCOM) when the network three-phase voltage is unbalanced, and achieves excellent effect of voltage control. For the non-uniform parallel transmission lines with single path shunt-compensated by STATCOM, operation condition of the impedance relays with short-circuit fault on the line is analyzed. It is confirmed that STATCOM under unbalanced control strategy may cause fault phase under-reaching and non-fault phase over-reaching. Considering current injection from STATCOM, modified fault location method is proposed. The measuring impedance of distance protection is corrected through coordinating the fault distance with the positive impedance of the line. Simulation results show that the modified algorithm guarantees correct operation of impedance relays, avoiding re-tuning distance protection after joining in STATCOM.%在电网三相电压不对称时，采用不对称控制策略能够保证静止同步补偿器（STATCOM）安全，实现良好的电压控制效果。针对较为复杂的单回并补双回线路，分析了线路短路后距离保护动作条件，证实采用不对称控制策略的STATCOM可能引起故障相保护拒动及非故障相保护误动。计及STATCOM注入电流，改进了故障测距算法。将故障距离值与线路正序阻抗配合，修正距离保护测量阻抗值。仿真结果验证了所提算法能够保证距离保护正确动作，避免接入STATCOM后重新整定距离保护。