Autonomous electrical power supply systems—wind/photovoltaic/diesel/battery

Abstract

A modular system for the supply of remote electrical consumers was developed, which makes possible a variable integration of wind energy and photovoltaic plants in connection with a diesel engine and battery storage. The wind energy converters, equipped with asynchronous generators, and a fast pitch control, work in parallel with a synchronous generator. The generator is driven by a diesel engine by means of an overrunning clutch, and is started by a small d.c. motor. If the diesel is off, or the starting process by the d.c. motor is finished, the synchronous generator works as a rotating phase-shifter and takes over voltage control and supply of reactive power. The speed versus power control of the wind energy converters makes possible an optimized parallel operation with the diesel-generator unit, and also directly takes over frequency control when operated singly without the diesel engine. The location of the wind turbine does not depend on the site of the diesel engine, because control cables are not necessary. To avoid too frequent starting of the diesel, a storage battery is installed. This paper describes the electrical and control design as well as the experience with the following, already built plant: -coupling of two wind turbines for the supply of water irrigation pumps, -combination of two WECs with a battery and a diesel-set, -combination of two WECs with a photovoltaic generator and a battery.