Operation and control of grid connected wind — PV hybrid system

This paper deals with the operation and control of a hybrid power system powered by wind and photovoltaic sources. A utility grid connection is provided in order to replenish energy levels in case of power shortage from the renewable energy sources. The hybrid system is a combination of two sources via a common DC bus. The renewable energy sources are connected to the main DC bus using a Multiple Input Ćuk converter. A Permanent Magnet Synchronous Generator (PMSG) is used to drive the wind turbine. Variations in wind power and solar irradiance are considered. The MI Ćuk converter tracks the maximum power point for each of the sources individually. The input current control method for MPPT of wind turbine and incremental conductance method for PV are discussed. The simulation is done in MATLAB/Simulink based on a 30kW wind-solar hybrid power system and the performance of this system is analysed based on the availability of sources. This system not only can produce electricity from the renewable energy sources, but also can inject surplus power to the utility grid after feeding the local ac loads, under varying source and load conditions. Control of the grid connected inverter maintains the ac load voltage and frequency of the system constant. LC filter along with inverter control maintains the ac load voltage harmonics within limits.