Design and Analysis of a Grid Connected Photovoltaic Generation System with Active Filtering Function

Abstract

In recent years there has been a growing interest in moving away from large centralized power generation toward distributed energy resources. Solar energy generation presents several benefits for use as a distributed energy resource, especially as a peaking power source. One drawback of solar energy sources is the need for energy storage for the system to be utilized for a significant percentage of the day. One way of avoiding adding energy storage to a solar generation system while still maintaining high system utilization is to design the power conversion subsystem to also provide harmonic and reactive compensation. When the sun is unavailable for generation, the system hardware can still be utilized to correct for harmonic and reactive currents on the distribution system. This system's dual-purpose operation solves both the power generation need, and helps to improve the growing problem of harmonic and reactive pollution of the distribution system. A control method is proposed for a system that provides approximately 1 kW of solar generation as well as up to 10 kVA of harmonic and reactive compensation simultaneously. The current control for the active was implemented with the synchronous reference frame method. The system and controller was designed and simulated. The harmonic and reactive compensation part of the system was built and tested experimentally. Due to the delay inherent in the control system from the sensors, calculation time, and power stage dynamics, the system was unable to correct for higher order harmonics. To allow the system to correct for all of the harmonics of concern, a hybrid passive - active approach was investigated by placing a set of inductors in series with the AC side of the load. A procedure was developed for properly sizing the inductors based on the harmonic residuals with the compensator in operation.