电网电压不平衡时逆变器无交流电压传感器控制策略

针对非理想电网电压条件,研究一种适应电网电压不平衡情况的并网逆变器无交流电压传感器控制策略。首先基于二阶广义积分器构建正交滤波器及适合电网电压不平衡条件的三相并网逆变器电压观测器,在两相静止坐标系下对电网电压进行观测;然后基于正交滤波器输出量进行正、负序分离,使正、负序分离与电网电压观测同步进行;最后结合逆变器在两相静止坐标系下的PR控制,并采用负序补偿算法,实现逆变器在电网电压不平衡条件下的无交流电压传感器控制。该策略能够避免传统虚拟磁链观测中的积分饱和、初值敏感、静态误差等问题,并克服现有基于正交滤波器的逆变器无交流电压传感器控制无法适应电网电压不平衡情况的问题。通过仿真与实验验证了所提出策略的有效性。

AC Voltage Sensorless Control Strategy of Grid-Connected Inverter under Unbalanced Grid Voltage

In order to adapt to the non-ideal grid voltage conditions, a AC voltage sensorless control of 3-phase voltage source inverter under unbalanced grid voltage has been researched. Second order generalized integrator is used to build quadrature filter and voltage observer for unbalanced grid voltage, and grid voltage can be hence observed directly in the two-phase static coordinate. Then positive and negative sequence separation can be carried out by using outputs of the quadrature filter, which also can be synchronized with the grid voltage observation. Finally, combined with PR control in the two-phase static coordinate of the inverter and negative sequence compensation algorithm, the AC voltage sensorless control of the inverter under unbalanced grid voltage can be achieved. Compared with the conventional virtual flux observation, the proposed method can get rid of the problems of windup, initial value sensitivity and static error, and also overcome the problem that the conventional quadrature filter based AC voltage sensorless control cannot adapt to the unbalanced grid voltage. The proposed methods and theories have been verified via simulations and experiments.