适用于不同类型滤波器的光伏逆变器控制策略研究

Study of Control Strategy for PV Inverter Considering Impact of Filters

针对含不同类型滤波器的三相逆变器采用不同控制策略的问题,分析了含不同类型滤波器的逆变器控制策略和实现方法,提出了一种适用于不同类型滤波器的逆变器控制策略。该控制策略基于αβ坐标系,将三相逆变器的控制转换为2个单相逆变器的控制,避免了复杂的坐标旋转变换和前馈解耦控制,可有效提高控制效率,降低控制器成本;并且使正常情况下的稳定运行控制、故障情况下的低电压穿越(LVRT)控制以及孤岛情况下的电压/频率(u/f)控制之间的转换相对方便,只需根据并网点电压及孤岛信号来确定工作状态,通过简单的开关转换即可满足含不同类型滤波器的逆变器在各种工作状态之间的转换操作,稳定性好,操作方便。在PSCAD/EMTDC上搭建光伏电源及控制模型,仿真结果表明该控制策略适用于不同的运行工况,验证了控制方法的有效性。

In the light of the problem of using various control strategies for three-phase inverter with different types of filter, this paper puts forward a control strategy applied to the inverter with different filters based on the analysis of control strategy and corresponding implementation for the inverters with diverse filters. The proposed control strategy is performed in theαβ coordinate system, to separate the control procedure of a three-phase inverter into two single-phase inverters control, avoiding the complex transform of coordinate rotation and feed-forward decoupling, which improves the control efficiency and reduces the cost of controller. Besides, it is relatively convenient to switch the control strategy among different operation modes such as stable operation, low voltage ride through under fault condition and islanding operation. According to the voltage at the point of common coupling （PCC） and islanding signal, the working condition is determined, and the working mode is changed by using simple switch operations. This control strategy keeps stable performance and easy implementation. PV power source model has been built by using PSCAD/EMTDC tool, and simulation results show that the control strategy is suitable for different operation modes, verifying the effectiveness of the control strategy.