Three Phase Single Stage Grid Synchronized PV Generator with Seamless Mode Transfer

This work presents the grid synchronized PV-VSC (Photovoltaic-Voltage Source Converter) with seamless mode transfer capability, which ensures electricity to local loads at the presence of PV panel power output more than the load power. These local loads are protected from the transients that occur due to sudden outage of the grid, and restoration of the grid. The performance of this system in grid synchronized mode and standalone mode at load dynamics, unbalancing in load currents, dynamic irradiance is investigated through the MATLAB simulated responses. The frequency adaptive moving average filter based control extracts the fundamental frequency orthogonal load current components. The transition mode control algorithm enables and disables the solid state transfer switch (STS) according to the criteria imposed by the IEEE-1547 standard to select the grid tied mode and a standalone mode function. The islanded mode control maintains the PCC (Point of Common Coupling) voltages in the close vicinity of the reference voltages. The PCC voltages are balanced on the occurrence of unbalancing of load in an islanded mode, while the grid currents are balanced even the unbalanced load is injected at the PCC. The total harmonics distortion of grid currents and the PCC voltages compliance the limits of the IEEE-519 standard.