Control Strategies of the Variable Speed Generating Systems

The paper presents a variable speed stand alone generating system. Such system called also as adjustable speed generating system is a modern technique that has great number of advantages over conventional synchronous generator driven with constant speed. In the adjustable speed generating system the prime mover drives a permanent magnet generator producing variable frequency and amplitude AC voltage. The variable voltage is conditioned by an AC/AC power electronic converter providing high quality multiphase AC sinusoidal voltage. The decoupling of the speed of the generator and output voltage frequency provides new way for optimizing prime mover like reducing of rated power, weight, emission and size and other optimization activities. In such generating systems prime mover speed control strategy is very important subject of investigation. The paper shows methods of control speed in stand alone adjustable speed generating systems. The paper presents performance of variable speed generating system according to implemented methods of speed control. The generating system was also equipped with additional controlled energy storage system made from supercapacitor bank. Energy provided by the supercapacitors allows to achieve good performance of the generating system during transient states. A simulation tests preliminary verifier developed methods of speed control, whereas presented laboratory tests results of the variable speed generating system with/without supercapacitor controlled energy storage system validates quality of the output voltage during transient states caused by steps of load.