不对称负载下离网逆变器的双序控制方法

输出电压的对称度是衡量三相离网逆变器性能的重要指标之一,而造成离网逆变器输出电压不对称的主要原因是负载不对称。常见的单序双闭环控制方法无法对负序电压进行控制,会导致输出电压不对称。为此,首先基于对称分量法推导了逆变器带不对称负载时输出分量的负序耦合公式,给出了负序电压的双闭环解耦控制方法。在此基础上提出一种双序控制方法,通过增加负序控制支路来对负序电压进行控制,保证离网逆变器输出电压的对称性。最后通过MATLAB进行对比仿真,给出系统相关参数,验证了这种控制方式的有效性。

Dual-sequence Control Method for Off-grid Inverter under Asymmetric Load

The symmetry degree of output voltage is one of the important indicators for measuring the performance of a three-phase off-grid inverter, and asymmetric load is the main reason for the asymmetry of output voltage from the off-grid inverter. The common single-sequence double closed-loop control methods cannot control the negative-sequence voltage, which will cause the output voltage to be asymmetric. In this paper, the negative-sequence coupling formula for the output component of the inverter under asymmetric load is deduced based on the symmetrical component method at first, and the double closed-loop decoupling control method for negative-sequence voltage is given. On this basis, a dual-sequence control method is put forward to control the negative-sequence voltage by adding a negative-sequence control branch, thus ensuring the symmetry of output voltage from the off-grid inverter. Finally, contrast simulations are carried out using MATLAB, and the relevant system parameters are given, which verifies the effectiveness of the proposed control method.