The new method of harmonic detection in microgrid electric vehicle charging stations based on the improved HHT

The appearance of microgrid solves the shortcomings of distributed generation and attracts the attention of the whole world. What´s more, it has brought both opportunities and challenges for the development of electric vehicle charging stations. But due to the increasing use of electric vehicle chargers, the harmonic pollution of microgrid is becoming more and more serious, and it causes harm to both electric equipments and large power grid. Taking measures to govern the harmonic pollution is imperative, but before governance, the accurate and real-time detection of harmonic is indispensible. So this paper puts forward to use the improved HHT to detect the harmonics. The improved HHT combines the support vector regression machine and the mirror extension to improve the end effect of HHT and make the instantaneous frequency and amplitude become more meaningful. What´s more, the improved HHT can accurately detect the starting and ending time of harmonic disturbances. Through the simulation results, it can be confirmed that this method is efficient and applicable for the harmonic detection in microgrid electric vehicle charging stations.