THE INFLUENCE OF CABLE CAPACITANCE ON TRIPLEN HARMONICS PRODUCED BY SYNCHRONOUS GENERATOR

Generator neutral earthing resistor (NER) at Universiti Teknologi PETRONAS (UTP) power plant becomes high temperature during parallel operation with utility grid of Tenaga Nasional Berhad (TNB). Due to increase in triplen harmonics current that flow through the generator NER, it has been observed that cable capacitance allows triplen harmonics current to flow back to the generator neutral. The main objective of this study is to investigate the influence of cable capacitance on the triplen harmonics behaviour. Lab scaled experiments have been conducted to vary all parameters related to cable capacitance under various load impedance conditions in both island and parallel mode. Cable capacitance which depends on cable length, size and number of parallel cable, combined with load impedance determines the third harmonic current magnitude. The triplen harmonic current is proportional to the cable capacitance value. The presence of cable capacitance that interact with generator inductance resulted to series harmonic resonance at 9th and 15th harmonic order that causes high 9th and 15th harmonic current flowing between generator and cable capacitor. The author hope by the end of this project, the findings will help the industry to understand better the characteristics of triplen harmonic flowing through cable capacitance.