采用改进有源补偿技术的中性点电压柔性控制方法

传统的有源补偿中性点电压技术是通过向中性点直接注入理论计算得到的电流来实现的,且忽略了系统的绝缘电阻,这会影响中性点电压的抑制效果,并且不能对中性点电压进行柔性控制。当电网异动时,还需要频繁测量电网参数,使得该方法不适应系统结构、参数的变化。采用先向中性点注入某一初始电流,然后利用差分法的思想,同时控制注入电流的大小和相位,最终实现中性点电压的柔性控制。该方法不仅能抑制中性点电压为零,也能控制中性点电压到任意非零的目标值,有收敛速度快、能同时调节注入电流的大小和相位、能适应系统结构和参数的变化等优点,其可行性得到了仿真验证。

Flexible Control Method of Neutral Point Voltage Using Improved Active Compensation Technology

The method of traditional active compensation for the neutral point voltage is realized by injecting a theoretically calculated current into the neutral point of the distribution network(DN). The insulation resistance of the DN affecting the compensation effect on the neutral point voltage is usually ignored. Neither is it possible to control the neutral point voltage flexibly. When the parameters of DN change, the traditional method has to measure them frequently. So it isn''t effective for DN whose system architecture and parameters change frequently. A new method based on the idea of the difference method is proposed. By injecting an initial current into the neutral point of DN, and controlling the amplitude and phase of this current simultaneously, flexible control of neutral point voltage is achieved ultimately. Not only is this method able to suppress the neutral point voltage at zero, but also it can suppress the neutral point voltage to an arbitrary non-zero target. It has such advantages as fast convergence, simultaneous adjustment to the amplitude and phase of the injection current, and wide application range that together make it usable in the DN whose system structure and parameters change frequently. Its feasibility has been verified by simulation. This work is supported by National Natural Science Foundation of China(No. 51107143).