Autonomous control of a PWM inverter in islanded distributed generation with different feedback signals

A control strategy for PWM inverters in distributed generation system to operate in islanded mode is presented in this paper. The control system must provide sufficient active and reactive power to match the connected load, therein providing high power quality. The multiloop controller contains regulators for filter capacitor current, filter capacitor voltage, and real and reactive powers. The system modelling and controller description details of the proposed inverter based distributed generation system are given. The control system in this mode is based on voltage and frequency droop. A detailed analysis, based on the concept of harmonic impedance, establishes the appropriateness of capacitor current feedback versus other feedback control signals with respect to inverter power quality. To compensate the DSP calculation delay, a modified Kalman filter design is discussed. Simulation and experimental results are provided to demonstrate the validity of the proposed control method.