Research On Comprehensive Evaluation Method Of Coal Mine Power Quality

With the scale of coal mining enterprises expanding and the growing use of non-linearloads, coal mine power quality is deteriorated.The stand of power quality is directly related tothe economic benefits of the coal mine enterprises, the status of power quality in coal minepower management has become more and more important.Therefore, it has a profoundtheoretical and practical significance to establish a set of relatively complete, scientific,operational power quality evaluation index system and method. In this paper, according to thespecial requirements of coal mine electrical load, the current harmonic distortion based on themaximum demand load current was quoted, as well as distortion power factor considering thenon-sinusoidal current waveform. Then, this paper proposed a evalution index system suitablefor coal mine power network,which including voltage, current, power factor of three primaryindicators and twelve secondary indicators.This paper discussed the advantages and disadvantages of all kinds of weighting methodfirst of all.Then, two objective weight(G1method,superiority chart)and two subjectiveweight(entropy method, variation coefficient method)were combined together to establish theoptimal model and to get the index weight for power quality comprehensive evaluationthrough solving this optimal model.The analysis result show that, using combined weight,which integrated many objective and subjective weight to determinate the power quality indexweight, considered the power consumer’s different demands,and reacted the powerconsumer’s subjective will, as well react the objective reality which makes the weight canembody the change of the index’s data, so reaches the unification of subjective and objective.The evaluation result is in accord with reality.At last, this paper usd the combination of probability statisties and fuzzy mathematics toevaluate the coal mine power quality and analyze the evaluation results.The analysis resultsshow that applying this method proposed in this paper for the comprehensive evaluation ofpower quality can reflect the real condition of the power quality in coal mine power network. It is not only can realize the overall level evaluation of coal mine power quality,also theclassification index.The result of comprehensive evaluation is more objective,accurate andreasonable.