Study On The Comprehensive Evaluation And Selective Improvement Of Power Quality

Classifying method of power quality is emphasized, namely the continuous and the event-based, and the major differences between them are analyzed well in the paper. On this basis, power quality evaluation framework, which is consist of classified evaluation of power quality, and comprehensive evaluation based on meaningful classification, is proposed. In addition, comprehensive evaluation methods based on meaningful classification are explored from aspects, quantitative calculation and qualitative analysis.Least squares support vector machine (LSSVM) theory is applied to the comprehensively grade evaluation of continuous power quality. Based on the platform of MATLAB, comprehensively grade evaluation model of continuous power quality based on LSSVM is established, and its effect is great by testing the validation samples.Statistical models of direct economic losses of the event-based power quality are established, and economic losses evaluation model of voltage sag is presented, which fully considers the voltage tolerated curves of sensitive equipments, economic losses of kinds of voltage sag and frequency of sag. At the same time, quality loss function in the quality engineering theory is introduced into indirect economic losses of voltage sag, voltage swell and short interruption, so total economic losses of event-based power quality can be obtained. According to the "economic equivalent balance principle", economic equivalent time of voltage sag, voltage swell and short interruption could be calculated. On this basis, power supply reliability index of event-based power quality is proposed, which could realize the comprehensive evaluation of event-based power quality.Selective improvement of power quality is proposed against the monitoring point where comprehensive evaluation grade doesn't meet the specified requirement. By the analysis from overall to the local, one or several power quality problems having more serious effects are obtained. By comparing the different power quality problems selected to control, and costs and benefits of different treatment schemes, the most scientific treatment scheme of power quality could be get.