改进DQ变换在光伏逆变器并网控制中的应用

Application of improved DQ transformation in grid connection control of photovoltaic inverter

在三相系统中,可以采用坐标变换实现解耦控制,而在单相系统中,传统的坐标变换已经不再适用。为了实现单相光伏发电系统中逆变器输出有功功率和无功功率的解耦控制,同时实现光伏发电系统的并网同步控制,引入了改进的DQ变换理论。介绍了改进DQ变换的原理及DQ锁相环的构成,通过改进DQ变换方法和DQ锁相环,将DQ变换输出反馈实现另一个自由度电压的构成,实现单相光伏发电系统的解耦控制和同步并网控制,对于逆变器采用三闭环控制,仿真结果验证了方案的可行性。

The decoupling control can be realized by adopting coordinate transformation in three-phase system,while the traditional coordinate transformation is no longer applicable in single phase system.In order to realize the decoupling control of active and reactive power of inverter in single phase photovoltaic power generation system and realize the grid connection synchronous control in single phase PV system,the improved DQ transformation theory was introduced.The principle of improved DQ transformation and the structure of DQ phase lock loop were introduced.The decoupling control and synchronous control in single phase PV system are realized through the improved DQ transformation theory and DQ phase lock loop,and another phase of voltage was structured by DQ transformation output feedback.A three closed loop control scheme was applied in the inverter control,and the simulation result proves the practicality of the method.