Harmonic Pollution Level Assessment in Distribution System Using Extended Cloud Similarity Measurement Method

The purpose of harmonic pollution level assessment is to judge whether the harmonic pollution of a bus or a region is beyond the limit. Considering the fuzziness of the index criteria values caused by harmonic variation,this paper proposes an assessment method for harmonic pollution level based on the extended cloud similarity measurement. Firstly, according to the main characteristics of harmonic pollution, a set of evaluation index of harmonic pollution level is formed, including the total harmonic distortion rate of voltage,the fifth harmonic current RMS value, the seventh harmonic current RMS value,the eleventh harmonic current RMS value, and thirteenth harmonic current RMS value. Secondly, considering the group decision-making behavior of the harmonic pollution level assessment, the group eigenvalue method is utilized to integrate the weight of multiple operators and to calculate the comprehensive weight of the assessment index. On this basis, the harmonic pollution are divided into four levels, and the index criteria values are expressed as triangular fuzzy numbers. Besides, the fuzzy numbers are unified by the extended cloud.Finally, the extended cloud similarity and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is utilized to get the evaluation results.The monitoring data of seven 10 kV buses in Guangzhou is adopted to verify the validity and rationality of the evaluation method.