Neutral Earthing Reactance Design in Mitigating Third Harmonic Current at the Generator Neutral

Third harmonic (TH) is a component of triplen harmonic which is a type of waveform distortion originated from non-linear loads and synchronous generator. TH current from synchronous generator returns to its neutral via cable capacitance or other neutral grounding points in the network has caused the Neutral Earthing Resistor (NER) to experience high temperature. One of the solutions to mitigate the TH current is to use a suitable design of Neutral Earthing Impedance (NEI). In this project, the commonly used NEI device namely NER and Neutral Earthing Reactance (NERX) are being studied. Universiti Teknologi PETRONAS (UTP) distribution system is modelled in MATLAB Simulink in order to simulate the flow of TH current within the system under normal steady state condition. Once verified, grounding methods including different NEI types and several grounding configuration are applied to the developed model and the resulting behaviour of TH current for each methods and configuration is analyses.