Grid-Connected Control System for Three-Phase Bidirectional DC/AC Converter to Exploit Photovoltaic Power Generation

Abstract

Abstract:A grid-connetected control system is proposed in this paper to regulate three-phase bidirectional DC/AC converters in distribution grid exploiting photovoltaic power generation and not having energy storage at the DC side. To interact power flow at two its sides, statbilize voltage at the DCbus and synchronize with the grid, it includes an inner current controller and an outer voltage controller in a cascaded structure. Using small signal modeling and information about voltage at the point of common coupling and DCbus, control parameters for controllers are determined to balance power between photovoltaic system side and grid side. Simulation results show that the grid-connected control system helps the three-phase bidirectional DC/AC converter meet all requirements very well due to the balance of power at its sides to hold voltage at DC side at a fixed value, grid synchronization and low harmonic distortion total for current and voltage waveforms. They also represents the capability to exploit maximum available power of photovoltaic power generation under any operational condition.