一种并网逆变器无交流电压传感器控制策略研究

Research on a kind of AC Voltage Sensorless Control Strategy of Grid-connected Inverter

针对配电电压波动较大等问题,研究了一种基于正交滤波器的并网逆变器无交流电压传感器控制策略。首先利用二阶广义积分器对特定频率交流信号的无差跟随特性构成正交滤波器,然后使用该正交滤波器构建三相并网逆变器的电压观测器,在两相静止坐标系下直接对电网电压进行观测,结合三相并网逆变器在两相静止坐标系下的PR控制,实现逆变器在无交流电压传感器条件下的运行控制。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。通过仿真与实验验证了所提出策略的有效性。

To reduce the impact of voltage fluctuations in distribution network, a Quadrature Filter（QF） based AC voltage sensorless control of 3-phase voltage source inverter has been proposed. The Second Order Generalized Integrator（SOGI） based Quadrature Filter outputs two quadrature signal with certain frequency, which eases the observation of grid voltage. Then the voltage observer of the inverter is built by the Quadrature Filter, and the grid voltage can be observed directly in the two phase static coordinate. Combined with PR control in the two phase static coordinate of the inverter, the AC voltage sensorless control of the inverter can be achieved. Compared with conventional virtual flux observation, the proposed method can get rid of the problems of windup, initial value sensitive and static error. Analysis shows that the proposed method does not reduce system stability. All the proposed methods and theories have been verified via simulations and experiments.