Performance Comparison of Standalone AC Microgrid with Inner Loop Proportional Integral and Proportional Resonant Current Controllers

Due to the depletion of conventional energy sources and to enrich the increasing energy demand results the new concept of microgrid. Microgrid includes renewable energy sources (RES), Energy storage System (ESS), Distributed Generation (DG's) and loads in microgrid power electronic converters (PEC). PEC plays a key role in the integration of RES and ESS for energy distributed system. It assists in controlling, converting, and consumed or stored energy. Microgrid enhances the uninterruptable supply at good quality of power, reliable, stability and load sharing methodologies. Conventionally, for standalone system, the outer voltage control loop is followed by inner current control loop. The comparison of inner loop Proportional Resonant (PR) current controller using stationary reference frame and the inner loop Proportional Integral (PI) current controller using rotating reference frame is presented. Analysis of inner loop PR current controller over the inner loop PI current controller is implemented for standalone AC microgrid. It also deals with study of employment of inner loop PR current controller compared with conventional inner loop PI current controller. The inner loop PR current controller has the following advantages- steady-state error zero for sinusoidal waveforms having the same resonant frequency, lower order harmonic compensation (HC) and acts like a resonant filter. Different resonant frequencies with multiple inner loop PR current controller can operate in parallel without interfering with each other. Analysis of both the inner loop current controllers done by using MATLAB/Simulink.