VOLTAGE AND FREQUENCY CONTROL OF PARALLEL OPERATED SYNCHRONOUS AND INDUCTION GENERATORS IN MICRO HYDRO SCHEME

Abstract

The induction generator 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 parallel with the synchronous generator for increase in demand of the load. The major drawback of the induction generator is its poor voltage regulation. This is due to its unbalance of reactive power supplied by the excitation capacitors and that demanded by the load and the machine. In this work, an excitation control system is designed to change the reactive power supplied by the system as per the load thereby attaining good voltage regulation. Another major challenge is the frequency of supply supplied by the operation of the synchronous and asynchronous generators. The conventional control system is not cost effective for the stand alone generators or more than one generator feeding the local load. It is therefore envisaged that while using the combination of synchronous and induction generators can cut down the cost of electro-mechanical equipment. The synchronous generator may provide reactive requirements of the load. The frequency sensitive load controllers is proposed to provide a variable load in the system in order to make the load seen by two generators, due variation in the consumer load remains constant. This shall ensure the constant voltage and frequency operation of the system. • In this dissertation work, simulation model of the parallel operation of synchronous and asynchronous generators along with the electronic load controller and the excitation controller is developed. The hard ware implementation of electronic load controller and excitation controller has been done in both analog and digital way. For analog circuit, a simple PWM chip (SG3525) is used and speed is sensed from the tachogenerator for electronic load controller. Terminal voltage is sensed by using single phase transformer. For digital circuit, arduino(atmega 2560), an open source software is used.