DIGITAL VOLTAGE AND FREQUENCY CONTROLLER FOR SELF-EXCITED INDUCTION GENERATOR

Abstract

The self-excited induction generator (SEIG) is a suitable power generation source utilizing renewable energy sources due to its advantages like simplicity, low cost, ruggedness, little maintenance, brushless construction, self-protection capability, ability to generate power while driven at variable speed etc. as compared to conventional synchronous generator. These advantages facilitate induction generator operation in stand-alone/isolated mode or in parallel with synchronous generator for supplying local load and in grid mode. The self-excited induction generator has a major drawback of poor voltage regulation. The inherent poor voltage and frequency regulation. of the SEIG is due to the difference between the reactive power supplied by the excitation capacitors and that demanded by the load and the machine. This is a major bottleneck for its application in isolated mode. One way to regulate the voltage and frequency of SEIG is to maintain a constant load at its terminals. Under such operation, SEIG requires fixed capacitance for excitation resulting in a fixed-point of operation. For this purpose, a suitable control scheme is to be developed such that the load on SEIG remains constant despite the change in the consumer load. Also, such control scheme should be simple, economical, rugged, and reliable. In this dissertation work, simulation model of electronic load controller has been developed. The hardware implementation of electronic load controller has been done in both analogue and digital signal processing (DSP) circuit. For analogue circuit, a simple PWM chip (SG3525) is used and feedback voltage is sensed by using single phase step down transformer. For digital circuit, TMS320F28335 DSP has been used. And finally the performance, advantages and disadvantages of digital and analogue electronic load controller circuit have been discussed.