配网末端交直流系统功率互济方法研究

Research on Scheme of AC/DC System Interconnection at Terminal of Distribution Network

配电变压器在电力系统运行过程中会因负荷率较低存在欠载运行,也会因负荷率过高存在过载运行,同时过电流状态将造成设备过热及烧毁现象,严重影响电力系统供电的可靠性与经济性。为满足配网末端系统的动态平衡、经济与可靠运行,首先,根据每日不同时段配电变压器的负荷率确定电池储能装置充放电状态,提出在配网末端用户每日谷时段(22:00—次日8:00)对电池储能装置进行充电,而在用户每日峰时段(8:00—22:00)电池储能装置将储存的电能释放回电网的控制策略,以避免配网变压器出现欠载与过载现象;然后,建立了以储能为核心的交直流配网系统实现对配网末端的有功互济及就地无功补偿控制策略,并根据负荷功率变化提出了系统储能设备容量的基本配置方法;最后,通过仿真验证了所提功率互济控制策略的可行性。

During the process of power system operation, distribution transformer will be running at underload or overload status because of the low load rate or high load rate respectively. In addition, the overcurrent of distribution transformer will cause overheating for the equipment, which seriously affecting the power system reliability. Firstly, to meet the requirement of dynamic balance, operating economy and reliability of the terminal of distribution network system, a battery energy storage system （BESS） is introduced to avoid underload or overload of the distribution network transformer. Then according to the load rate of the distribution transformer during the different time interval daily, this paper studies a control strategy for the BESS by recharging the BESS during the electricity valley period （22：00--8：00 in the next day） and discharging the BESS during the electricity peak period （8：00--22：00）. The AC/DC hybrid system is established for the terminal of distribution network to achieve active power mutual aid and reactive power local compensation. Furthermore, the capacity of energy storage devices is configured based on the historical load curve of electric power system. Finally, the simulation results validate effectiveness of the proposed power mutual aid control strategy.