Electrical Load Emulation using Optimal Feedback Control Technique

The paper presents a method of emulating electrical loads using power electronic converters. The loads include machines such as induction motors and their associated mechanical load and also more complex machine systems such as wind-driven generators. The load emulator is effectively a dynamically controllable source or sink which is capable of bidirectional power exchange with either a grid or another power electronic converter system. Using load emulation, the feasibility of connecting a particular machine to a grid under various load conditions can be examined without the need for any electromechanical machinery. The paper considers the case of a power electronic Voltage Source Inverter (VSI) emulating a three phase induction motor connected to a three phase ac grid. The VSI is operated in a mode where the current drawn from the ac grid is controlled by closed loop control. Experimental results are provided to verify the scheme.