35 kV/8 Mvar链式直挂STATCOM已研制完成并投入运行,采用星型接线和自励启动。该装置的各链节采用自取电及互取电技术,可在单个链节故障时自动旁路从而实现了不停电(N-1)运行; 整个STATCOM采用了综合优化载波移相PWM、 分相瞬时电流控制和基于电压差值的直流电压平衡的控制方法,实现了动态无功输出; 为满足变电站功率因数考核要求,该STATCOM装置还采用了与变电站VQC系统协调控制的策略。经实际测试,装置效率可达99%以上,链节间直流电压的不平衡度在3.3%以下; 在系统电压跌落时STATCOM的无功输出响应时间小于 10 ms, 可有效支撑系统电压; 能较好地与VQC系统协调运行,实现了功率因数稳定控制。试验结果及现场运行数据表明该链式STATCOM的各项性能指标都达到了预期的目标。

A 35 kV/8 Mvar cascaded transformerless static synchronous compensator (STATCOM) has been developed as a star configuration with self-excitation. With multiple power supplies, each unit can be automatically bypassed when a fault occurs to implement (N-1) uninterrupted operation. The compensation uses the optimized carrier phase-shift PWM method, instantaneous current control and a capacitor balancing strategy based on the voltage difference to give fast dynamic reactive power compensation. The STATCOM also coordinates with the voltage and reactive power control (VQC) system. Tests show that the STATCOM efficiency reaches 99%, the degree of unbalance among units is not greater than 3.3%, and the response time is below 10 ms when a voltage sag is detected which maintains the power system. The power factor is also related to the coordination between the STATCOM and VQC systems. Experimental data and field operation results both show that the excellent performance of the transformerless 35 kV/8 Mvar STATCOM as a new solution for voltage and reactive power control in substations.