不平衡补偿时静止同步补偿器的分相控制

通过分析不平衡补偿时补偿器输出电压与补偿电流的关系,并利用三相三线系统中没有零序电流通道的特点,证明了通过向补偿器三相输出电压中加入零序分量,能够达到使其输出电压幅值相同的目的。基于此原理,提出一种配网静止同步补偿器在不平衡补偿时的分相控制方法。该控制方法以各相无功功率为零作为控制目标,在保持调制比相同的情况下通过调节补偿器各相输出电压相对于系统电压的相角差δ来调节各相的输出电流,实现了补偿器的分相控制。通过分析说明了采用该控制方法的系统达到稳态时,电网电流三相平衡且功率因数为1,达到了无功补偿和负载功率平衡的目的。利用Matlab对分相控制方法进行仿真,仿真结果验证了该控制方法的正确性和有效性。

Individual phase control of D-STATCOM under unbalanced compensation

The relationship between the output voltage and compensating current of D- STATCOM under unbalanced compensation is analyzed. Because there is no zero sequence current in three -phase three-wire system, it is proved that, the three-phase output voltages of compensator may get same magnitude by adding zero sequence components to them. Based on this principle,an individual phase control method of D-STATCOM under unbalanced compensation is proposed,which keeps the reactive power of each phase zero as the control objective,adjusting the output current of each phase by regulating its phase difference 8 between compensator output voltage and line voltage while maintaining the modulation index constant. Analysis shows that,when the system controlled by this method reaches steady state,the three-phase line currents are balanced and the power factor is one. Matlab-based simulative result verifies its validity and feasibility.