配电网电压不平衡下级联型DSTATCOM控制方法研究

Research on Cascade DSTATCOM Control Method in Distribution Network with Unbalanced Voltage

研究了配电网电压不平衡下级联多电平配电静止同步补偿器(DSTATCOM)的控制策略。实际运行中,配电网电压不平衡工况会严重干扰DSTATCOM的安全稳定运行。在该工况下,DSTATCOM会产生很大的负序电流,且自身会出现二倍频的直流电压分量和三倍频的交流电流分量,严重影响开关等元件寿命、控制动态性能和无功补偿能力。因此,提出基于负序控制、零序电压注入和子模块直流电压均衡控制结合的控制方法,以应对配电网电压不平衡的问题。负序控制的作用是控制和降低负序电流,而零序电压注入和直流电压均衡控制可以抑制二倍频的直流电压分量和三倍频的交流电流分量。最后,通过对详细模型的时域仿真,验证了该方法的正确性和可行性。

The control strategy of cascaded multilevel static synchronous compensator(DSTATCOM)for distribution network with unbalanced voltage is studied.In actual operation,the unbalanced voltage of distribution network will seriously interfere with the safe and stable operation of DSTATCOM.Under this working condition,DSTATCOM will produce a large negative sequence current,and it will produce DC voltage component of double frequency and AC current component of triple frequency,which will seriously affect the life of switch and other components,control dynamic performance and reactive power compensation ability.Therefore,a control method based on negative sequence control,zero sequence voltage injection and submodule DC voltage equalization control is proposed to deal with the problem of voltage imbalance in distribution network.The function of negative sequence control is to control and reduce negative sequence current,while zero sequence voltage injection and DC voltage equalization control can suppress DC voltage component of double frequency and AC current component of triple frequency.Finally,the correctness and feasibility of the method are verified by time domain simulation of the detailed model.