Impact of load and speed variation to frequency variation on single-phase self-excited induction generator

Abstract

The induction generator has a sturdy, simple, reliable, inexpensive construction and little maintenance compared to a synchronous generator. Induction generators also have self-protection against overload and short circuit. Loads in remote rural areas are generally single-phase loads, it would be more advantageous if the generator used is a single-phase induction generator. The construction of a small-scale power plant that uses single-phase self-excited induction generator becomes one of the promising options. The induction generator can operate in two modes, that is connected to the grid and stand-alone. Stand-alone induction generator cannot generate reactive power. Therefore, for a stand-alone induction generator, a capacitor is required to be mounted on the coil terminal for excitation. Capacitors can produce the required reactive power for generator excitation and the load simultaneously. The induction generator can only generate active power. It is therefore only suitable for resistive loads. When load changes occur, the input power changes of the generator must able to compensate. Generator input power is the mechanical power of torque and rotation of the generator shaft. The output voltage frequency of the self-excited generator is unlike the output voltage frequency of the synchronous generator. The output voltage frequency of the synchronous generator voltage is proportional to the rotation speed and the number of poles. Meanwhile, the output voltage frequency of the self-excited induction generator is affected to both rotation speed of the shaft and the load changes. The results showed that any increase in the load needs to increase the rotation speed and any increase in the frequency is not proportional to the rotation speed. This study aims to obtain the relationship of how much influence the load variation on the frequency variation with the voltage kept constant and rotate slightly above the synchronous speed.