一种新型的中性线电流补偿器

Compensator for neural line current

针对目前非线性负荷造成低压配电网中性线过负荷的问题,提出一种新型的中性线电流补偿器。该新型补偿器将逆变器接入曲折变压器中性点和中线之间,逆变器输出的电流通过曲折变压器提供的低阻抗的零序电流通道注入系统,进行中性线电流的补偿。曲折变压器的二次侧输出利用全控整流桥整流,为逆变器提供直流电源,实现了能量的双向流动,有效地解决了采用不控整流模块时,在补偿器吸收有功功率的情况下所造成的直流电压升高,易造成开关器件过压损坏的问题。通过建立模型对提出的补偿器进行仿真研究,结果表明该新型中性线电流补偿器能够有效地补偿中性线中的谐波及不平衡电流,逆变器的直流侧电压保持稳定。

A neural line current compensator is proposed to solve the problem of neural line overload caused by the nonlinear and unbalanced loads in distribution system,which connects a single-phase inverter between the neural point of zigzag transformer and the neural line. The output current of the inverter is injected into system through the path provided by the zig-zag transformer for neural line current compensation,which is of low impedance to the zero-sequence current. The output of the zigzag transformer at secondary side is commutated by a controllable rectifier to supply DC voltage for the inverter. If the uncontrollable rectifier is applied,the DC voltage arises when the compensator absorbs the active power. With the controllable rectifier, energy flows in both directions to avoid the DC voltage elevation and switching device damage. Modeling and simulation show that,the proposed compensator eliminates the neural line current effectively and the DC voltage of inverter keeps steady.