基于功率转移的混合级联电压均衡控制策略

A Cluster Voltage Balancing Control Strategy Based on Active Power Exchange

传统星形级联H桥(CHB)静止同步补偿器(STATCOM)补偿负序电流时会产生不平衡三相有功功率,造成相间直流电压不均衡。通常只能通过注入零序电压重新分配三相有功功率,来实现相间直流电压均衡。然而,零序电压注入将极大地增加STATCOM的输出电压,限制了负序电流补偿范围。以混合级联型STATCOM为研究对象,给出一种通过共直流母线单元来转移相间不平衡有功功率的方法,并以此提出相间均压控制策略。最后,在7.5 kvar的混合级联型STATCOM实验平台验证所提相间均压控制策略的可行性。

The traditional star cascade H-bridge(CHB) static synchronous compensator(STATCOM) will generate unbalanced three-phase active power when compensating for negative-sequence current,resulting in unbalanced phase-tophase DC voltage.Phase-to-phase DC voltage balance can usually only be achieved by redistributing three-phase active power by injecting zero-sequence voltages.However,the zero-sequence voltage injection will greatly increase the output voltage of the STATCOM,limiting the compensation range of the negative-sequence current compensation.The hybrid cascaded STATCOM is taken as the research object,and a method to transfer the phase-to-phase unbalanced active power through the common DC bus unit is presented,and based on this,a phase-to-phase voltage balance control strategy is proposed.Finally,the feasibility of the phase-to-phase voltage balance control strategy proposed is verified on the 7.5 kvar hybrid machine-connected STATCOM experimental platform.