Effective power transfer scheme for a grid connected hybrid wind/photovoltaic system

A new topology and effective power transfer scheme with minimum number of converters is proposed for a grid connected wind/photovoltaic (PV) system. Distributed generation sources considered are permanent magnet synchronous generator (PMSG)-based wind energy conversion system and PV array system. Two voltage source converters with a common DC-link serve as wind side converter (WSC) and grid side converter (GSC), respectively. The PV array is directly tied to the DC link without any power converter providing variable DC-link voltage. The Perturb and Observe technique extracts the maximum power from PV and the DC-link voltage is set to the maximum power point (MPP) voltage of the PV array. The output DC voltage of WSC is regulated to an MPP PV voltage using an outer proportional-integral voltage control loop. The maximum power from the PMSG and stator voltages is utilised to generate the reference currents for WSC to make stator currents to follow stator voltages. With unity power factor control, the overall VA of the WSC would contribute to the active power transfer and thereby reduce the kVA rating of the WSC in the proposed configuration. GSC tracks the maximum power from wind and PV array, and serves as a shunt active power filter to compensate for the current unbalance due to the connection of non-linear loads at the grid. All these functions are accomplished simultaneously. Various power transfer modes of operation are simulated through MATLAB/Simulink software and its results are validated through dSPACE Digital Signal Processor.