基于平衡补偿法对负载中性点偏移电压的测量

摘要

配电系统中一般已知三相电压以及三相功率潮流,不能测出负载端中性点偏移电压,而在建立并求解三相电源电流数学模型的前提是必须已知中性点偏移电压.介绍了一种根据平衡补偿法测量中性点电压偏移量,应用并联补偿装置对不对称负载进行平衡补偿,得出补偿后系统对称电流和对称阻抗.采用不对称负载和补偿电抗的星三角变换对不对称负载进行修正,依据补偿前不对称电流等于负载电流为条件重复迭代计算精确求出不对称负载,并求得中性点电压偏移量.最后依据广东某一变电站为例,计算并用Matlab仿真证明了该方法的正确性.%Three-phase voltage and power flow can be given in distributed system, while load side neutral point voltage offset cannot be measured in the substation, but the premise of establishing and solving the three-phase power supply current mathematical model must be known neutral point voltage offset.A kind of neutral point voltage offset measurement method based on balanced compensation method has been introduced in this paper, and the parallel compensation device is used to compensate the asymmetric load, thus the symmetric current and impedance of compensation system are obtained.The star triangle asymmetric load and reactive compensation transformation are used to modify asymmetric load, according to the compensation current is equal to the load current is asymmetric conditions before repeating iterative calculation precision and asymmetric load, and the neutral point voltage offset is obtained.Finally, on the basis of a transformer substation of Guangdong province as an example, the calculation and Matlab simulation prove the correctness of the proposed method.