The comparison analysis of typical control strategies for LCL type inverter in Frequency domain

The LCL type inverter plays a significant role in the grid integration of renewable energy, the control strategies are the key factor to influence the performance of inverter. In this paper, several typical control strategies in synchronous or stationary frame for LCL type inverter are compared and analyzed in frequency domain to interpret the similarities and differences among them. First, the transfer functions of control strategy in synchronous frame are deduced to the stationary frame in frequency domain. Then, all of control strategies are compared and analyzed in the stationary frame to derive the essential reason of similarities and differences in detail. It is shown that the performance of PI controller in synchronous frame and PR controller in stationary frame can achieve the zero steady state error since two transfer function of are similar, however, PI controller in stationary frame cannot eliminate the steady state error because the integration of PI controller is only suitable for dc component. At last, the simulation platform is built in MATLAB Simulink, the simulation result verified the above analysis of transfer function in frequency domain.