Electrical equipment for a combined wind/PV isolated generating system

Wind and solar photovoltaic generating systems have advanced rapidly in recent years, but both suffer from the intermittent nature of their resource. A secure stand-alone power supply based on either requires a substantial energy store. Combining the two creates a supply with smaller storage requirement since the fluctuations have a statistical tendency to cancel. The system developed for a 10 kW application comprises wind and solar collectors, each of 5 kW rating, with a lead-acid battery for storage and a 10 kW PWM inverter for the final output. The wind turbine generator is a 5 kW, 200 RPM, direct-drive, permanent-magnet, axial-flux machine based on the `Torus' configuration. The three-phase output is rectified to form a variable voltage DC link. The power converter uses two DC-DC power converters connected in series, each with a bypass diode which conducts continuously when the corresponding source is not available.