链式STATCOM的直流电容电压平衡控制策略

Direct Current Capacitor Voltage Balancing Control Strategy for Cascade STATCOM

针对链式静止同步补偿器(STATCOM)中链节直流电容电压不平衡的问题,提出基于有功功率分配的分级平衡控制方法。第1级通过解耦控制完成系统有功和无功控制,实现与电网总有功功率的交换;第2级采用与各相无功电流方向平行的控制量来调整三相之间的有功功率分配,实现相间的电容电压平衡控制;第3级采用与输出电流方向平行的有功电压对同相内的链节进行有功分配,实现相内的直流电容电压平衡控制。最后,研制了一台三相9个链节的链式STATCOM实验样机,并在样机上进行直流电容平衡的实验,验证了所提控制方法的可行性和有效性。

Aiming at the problem of unbalanced direct current capacitor voltage in the cascade static synchronous com pensator (STATCOM ), a hierarchical balancing control method based on active power distribution is proposed. In the first layer,the active power and reactive power are controlled by decoupling control and the total active power is ex changed with the grid.In the second layer, the active power distribution between the three phases is adjusted by the control variables parallel to the reactive current direction of each phase, and the capacitor voltage balance control be tween the three phases is realized.In the third layer, the active voltage parallel to the output current direction is used to distribute the active power among the in-phase links to realize the direct current capacitor voltage balance control in the phase.Finally, an experimental prototype of a three-phase nine-link cascade STATCOM is developed and the direct current capacitance balance experiment is carried out on the prototype which verifies the feasibility and effec tiveness of the proposed control method.