Improving connection and disconnection of a small scale distributed generator using solid-state controller

Self excited induction generator is extensively used in renewable energy sources such as small & large wind farms, small hydroelectric power plant and recently in micro combined heat and power systems muCHP. When connecting this unit to the grid a high transient current will flow. There will be a large, very fast, magnetic inrush current similar to that which occurs when a transformer is energised. This paper presents a solid state controller using coolMOS devices for improving connection and disconnection of the induction generator to and from the grid. The behaviour of the grid with connection/disconnection of the induction generator (islanding) through solid state controller have been simulated. Experimental model for solid state controller has been built using CoolMOS devices. Both simulations and experimental tests based on a laboratory 1.1 kW induction generator driven by a dc motor are clearly compared and show that the proposed controller are reliable and cost effective.