| With the rapid development of science and technology and the national economy,the amount of non-linear load access in the power grid continues to increase,and the penetration rate of distributed power sources is also constantly increasing,resulting in more and more power quality problems.On the other hand,the sensitive loads in the power grid are also increasing.Especially with the continuous advancement of the power market reform,people pay more and more attention to the quality attributes of electric energy,and have higher and higher requirements on the overall quality of electric energy.However,power quality is a complex with multiple indicators.It is impossible to judge the overall quality of power quality by evaluating individual power quality indicators.Therefore,it is of great theoretical and practical significance to study how to comprehensively,scientifically,reasonably and accurately evaluate the power quality.It is of great theoretical and practical significance to assess the quality of power,to realize the quality pricing of electric energy,and to promote the safe and healthy development of power grid and electricity market.Firstly,based on the status of power quality comprehensive assessment research and the definition of power quality comprehensive assessment,this paper considers that the research on comprehensive assessment of power quality includes three aspects:evaluation indexes,evaluation index weight,and comprehensive evaluation model.In this paper,the weight of the evaluation index and the comprehensive evaluation method are mainly studied and discussed.Secondly,on the basis of the research on the method of determining the weights of evaluation indicators,a weights combination optimization model based on the least square principle is established,and the punitive state variable weight vector is constructed.A new power quality comprehensive evaluation variable weight decision method is proposed.Through the detailed research and comparison of the fixed weighting methods for evaluating indicators,the advantages and disadvantages of several subjective and objective weighting methods are analyzed.Based on this,the subjective and objective weight combination optimization based on least squares principle is proposed.Considering the influence of deterioration of power quality index on index weight,a punitive state variable weight vector is constructed,and a power quality comprehensive evaluation variable weight decision method based on state variable weight is proposed.Through the analysis of practical examples,the validity and rationality of the established weight combination optimization model and the constructed punitive state variable weight vector are verified.It provides theoretical support for the improvement of the fuzzy comprehensive evaluation method.Then,based on the normal cloud model and the penalty state variable weight vector,a normal cloud model based power quality variable weight fuzzy comprehensive evaluation model is established,and an improved fuzzy estimation method for power quality is proposed.On the basis of comprehensive consideration of factors such as the connection between indicators and the practicality of the evaluation method in the process of comprehensive evaluation of power quality,combined with the comprehensive assessment process of power quality,the concept of the cloud cloud's definition of cloud in the normal cloud model is used to construct a fuzzy relation matrix.It replaces the membership function in the fuzzy evaluation process,avoiding the influence of subjective factors in the evaluation process.In addition,the limitations of the traditional fuzzy comprehensive evaluation process are overcome by combining the penalty state variable weight vector and the asymmetric proximity criterion constructed in the previous paper.Based on the above,a fuzzy comprehensive evaluation model for power quality based on normal cloud model is established.An improved fuzzy evaluation method for power quality is proposed,which realizes comprehensive evaluation and comprehensive quantitative evaluation of power quality.Finally,combined with the power demand side energy efficiency management system,and based on the E language development platform,the demand side energy efficiency management system host computer software including the power quality comprehensive evaluation function module is programmed and designed.On the basis of the overall architecture,hardware and software components and development platform of the demand side energy efficiency management system,and combined with the improved power quality fuzzy comprehensive evaluation method proposed in this paper,the design idea of the power quality comprehensive evaluation function module and the function interface in the upper computer are demonstrated.Through the application of the example and the analysis of the results,the practicability of the functional module and the rationality and effectiveness of the evaluation results are verified. |
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