三相不平衡条件下低压配电变压器合环操作研究

Study on Closed Loop Operation of Low Voltage Distribution Transformer under Three Phase Unbalanced Condition

采用合环操作实现不停电倒负荷可大大提高低压配电网供电可靠性,但由于低压电网中配电变压器负载不对称性和合环点存在电压差等因素,合环操作会改变配电变压器负载不平衡度,且操作中会产生合环冲击电流,对电网安全运行产生影响。对此,提出了适用于低压配电网配电变压器合环时电流和不平衡度的计算方法,给出了低压配变合环操作的判定条件,并通过仿真分析了低压配变负载率和不平衡度对合环电流及合环后配电网不平衡度的影响,验证了计算方法的正确性。

The use of closing loop operation can greatly improve the power supply reliability of low-voltage distribution network.Due to the asymmetry load of distribution transformer and voltage difference of both sides,the closed loop operation will change the load imbalance of power distribution transformer,and produce the closed loop impact current,which affects the security operation of the power grid.To solve the above problems,this paper proposed calculation method for closed loop current and imbalance degree of distribution transformer in low voltage distribution network.Determinant conditions of the closed loop operation in low-voltage distribution transformer are given.The influence of load rate and unbalance degree of low voltage distribution transformer on the closed loop current and the unbalance degree of distribution network after operation is simulated to verify the correctness of the calculation method.