Poisson Distribution based algorithm to reduce grid harmonics caused by EV chargers

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The global market of electric vehicles (EVs) is growing rapidly because of several factors such as growing concerns for pollution, governmental incentives/subsidies and regulations and consumers’ increasing interest in quiet, pollution-free vehicles. Many countries are determined to sell only EVs from 2035 onwards. With the increase of EVs, fast charging stations need to be installed at many facilities such as universities, shopping malls, hospitals, parking facilities etc. When many EVs start plugging into these facilities to charge, the grid power quality is expected to deteriorate, so it is important that the grid power quality be maintained in the most economical way possible. In this thesis, a new statistics-based algorithm is proposed to reduce the grid harmonics caused by EVs which are essentially non-linear loads. The proposed algorithm helps reduce grid harmonics by phase-shifting the carrier waves of each charging bay within a charging station. When the carrier waves are phase-shifted, the switching transients are distributed over time and some of the generated harmonics will cancel each other. This technique does not require any centralized communication or information exchange between the charging bays to coordinate the carrier waves. As an example, the algorithm is implemented in twenty (20) bays within a charging station by utilizing the Mean and Variance values of the Cumulative Poisson Distribution. This methodology is implemented using MATLAB Simulink platform and the performance is validated. The techniques have demonstrated a 30% improvement in the power quality of the grid voltage.
Electric Vehicles (EVs), Electric grid, Power quality, Harmonics, Poisson Distribution