Sensorless operation of a PWM rectifier for en-gen set as a distributed generation

In this paper an engine generator (en-gen) set is used as a distributed generation system. This paper presents the interface and control strategies for the en-gen set using a PWM rectifier without any ac reactors and voltage sensors. A scheme to estimate the generator's EMF voltage from the measurement of ac line currents, a method to get a synchronous angle from the estimated EMF voltages and techniques of obtaining the integrators' initial values in the estimator are proposed. The feasibility of the overall algorithms has been verified throughout experiments using a 35 hp commercial en-gen set.