Research On A Control Strategy Of Voltages And Power Flow On10KV Busbars

Distributed Generation (DG) is one of current main fields of power system and also an imperative part of the smart power grids in China. Though DG is highly efficient and environmentally friendly, it brings new problems such as the implement of distributed generators could lead the rise even violation of the bus voltage. Therefore, establishing proper Energy Management System (EMS) is crucial to the development of DG. Under the support from the projects, Research On Signal Processing Technology For Smart Sensor(No.08ZC010), Research On Highly Efficient Delivery Of Power With Strong Intermittency(No.Z2012015), Research On Highly Efficient Delivery Of Power With Randomness(No.13ZA0025) and another project(No.CHUANJIAOCAI[2013]203), for effictively increasing the reliability and penetration of DG, a control strategy for managing the voltages, currents and power flow on grid busbars is proposed.The power electronic device proposed in this paper consists of two back-to-back voltage-sourced converters (VSCs) and a direct current (DC) bus in the middle of the two VSCs. The DC bus is designed to work as a constant DC source. One of the two VSCs is designed as a rectifier to maintain the DC bus voltage. The other one is designed as an inverter to transfer desired power from the DC bus to grid. The filter for harmonics and control modules for device outputs on10KV busbars are designed. The external DC bus voltage control loop and the internal rectifier current control loop work jointly to maintain the DC bus voltage. The external critical load voltage control loop and the internal inverter current control loop work jointly to control the outputs of the device’s inverter-side. The performance of the device in normal condition and fault. conditions are analyzed via simulation experiments. In both conditions, the device can rapidly regulate the voltages, currents and power flow on the both sides of it. The total harmonic distortion (THD) meets the national standard. In islanded condition, the device works as a voltage source to supply the critical load and can respond to the load fluctuation in time. In three-phase short circuit condition, the device restricts the short-circuit currents, effectively decreasing the short-circuit current level.