Quantitative Analysis And Research On The Influence Of Composite Power Quality On The Loss Of Medium-and Low-Voltage Distribution Network

With the wide application of power electronics technology in distribution network and the increase of nonlinear,impact and asymmetric load,the problem of power quality is becoming more and more serious.As the main component of power loss,quantitatively analyzing the relationship between medium-and low-voltage distribution network loss and power quality can improve the accuracy of loss calculation and provide theoretical guidance for analyzing the composition of loss and formulating a reasonable loss reduction scheme.The main research work of this paper is as follows:First of all,based on the definition of power quality,this paper introduced the concept,cause,characterization index and national standard of three-phase unbalance,voltage deviation and harmonic steady-state power quality,the influence mechanism of each single power quality on the loss of main energy consumption equipment in medium-and low-voltage distribution network was briefly analyzed.Based on this,the single power quality additional loss calculation model of the main energy consumption equipment was established,and the distribution network under the action of each power quality was modeled and simulated in the MATLAB/Simulink simulation platform,the accuracy of the calculation model was verified,and the relationship between single power quality and additional loss was quantitatively analyzed.Secondly,based on the calculation model of additional loss of main energy consumption equipment under the action of single power quality,the calculation model of additional loss under the action of composite power quality was obtained,and the calculation model was verified by simulation,the relationship between three-phase unbalance,harmonic and additional loss was analyzed quantitatively.Based on this,the relationship between the composite power quality loss and the single power quality loss was further analyzed.From the symmetrical component method,it was found that the additional loss caused by the simultaneous action of three-phase unbalance and harmonics is not the linear addition of the additional loss caused by the action of the two alone.In order to accurately analyze the composition of additional loss under the interaction of composite power quality,an additional loss decomposition model was proposed,which decomposes the additional loss of composite power quality into the sum of each single additional loss of power quality,the correctness and rationality of the decomposition model were verified by simulation.Finally,combined with the measured data of the actual distribution network,the accuracy of the composite power quality additional loss calculation model was verified.The actual composite power quality additional loss was decomposed into the additional loss caused by each power quality by using the additional loss decomposition model,which can guide the effective implementation of power quality governance and energy saving and loss reduction scheme according to the size of each power quality additional loss.