H桥级联式SSSC直流侧电容值选择及自励启动充能策略

Selection of DC Capacitance and Schemes of Self-excitation Startup Charge for the H-bridge Cascading SSSC

为了保证H桥级联式静止同步串联补偿器(SSSC)的安全、稳定运行,减少其对电网的谐波注入,依据SSSC直流侧及交流侧的数学关系,提出了一种计及SSSC的输出谐波和直流侧电压波动的直流侧电容值的选择方法。根据SSSC与电网的串联结构关系,考虑到充能过程对电网的干扰最小,提出了结合电子旁路轮换的二极管整流、等效Boost电路及全有功脉宽调制(PWM)整流3种直流侧电容自励启动充能方案,其中全有功PWM整流方案综合性能最优。最后,通过EMTDC/PSCAD仿真及实验验证了文中结论的正确性。

In order to guarantee the safety and stability of the H-bridge cascading SSSC and to reduce the harmonics, based on the mathematical relationship between DC and AC side of the SSSC, this paper presents a formula of selecting DC capacitance with the output harmonics and fluctuation of DC voltage being taken account of. Considering the fact that the SSSC is connected to transmission line in series, the paper proposes three types of self-excitation charging schemes for the SSSC to achieve a minimal disturbance to the connected power grid. The proposed schemes are the electric bypass plus alternative charge including diode rectifier, equivalent Boost circuit and full active power PWM rectifier that gives best performance. Finally, results of EMTDC/PSCAD simulation and experiment are given in the paper.