基于序分量和量测值的三相不平衡度量研究

IEC序分量三相不平衡度量包括负序和零序三相不平衡度，使得三相不平衡度不具有唯一性。以量测的有效值度量三相不平衡度与序分量度量形式不具有对应关系，给工程使用带来困扰。基于序分量和相量的大小关系，提出采用正序分量有效值的平方和与总量平方和之比度量三相平衡度，统一了含零序和不含零序系统的度量形式。在此基础上，分别针对不含零序分量的线电压、线电流，含有零序分量的相电压、相电流，给出了根据量测有效值获取序分量大小的方法，构建与序分量度量对应的量测有效值度量形式。算例显示，提出的序分量度量方式适用于三相三线制和三相四线制系统，构建的量测值度量形式和序分量具有对应关系，保证了工程应用中三相不平衡度量的唯一性。

Research on three phase unbalanced ratio measurement based on sequence components and measured values

IEC separately defines the negative sequence and zero sequence three phase unbalanced ratio. So, the definition is not unique. The unbalanced ratio calculated by measured RMS values has no correspondence with the sequence component definition. It makes for confusion in actual engineering. Based on the size relationship between RMS of the sequence component and phasor, it is proposed to measure the three-phase balance ratio using the square of the three-phase positive sequence component RMS divided by the square of the phasor RMS. In this way the definition is unified no matter whether it is with or without the zero sequence component. On this basis, the method of using measurement values to get sequence components is constructed, aiming at both the line voltage and current without the zero sequence component and phase voltage and current with the zero-sequence component. The measurement RMS unbalanced ratio definition has correspondence with the sequence component. The examples show that the proposed method of sequence component measurement is more suitable for a three-phase three-wire system and a three-phase four-wire system. The definition based on measured values corresponds with the sequence component definition. It guarantees the uniqueness of the three-phase unbalanced ratio in engineering. This work is supported by National Natural Science Foundation of China (No. 51607083), Major Natural Science Research Projects of Jiangsu Province University (No. 17KJA470003), and Project of State Key Laboratory of Smart Grid Protection and Control.