Research On Comprehensive Evaluation And Application Of Power Quality For Microgrid Based On Dynamic Coefficient And CRITIC

The power quality assessment of microgrid provides scientific reference basis for the safe and stable operation of microgrid,and is important for the regulation of microgrid,and how to reasonably assess the power quality index of microgrid is also one of the key issues of microgrid power management.There are still some problems that should be improved when assessing the power quality of microgrid.For example,firstly,the traditional objective weighting method relies on a single data characteristic that cannot reflect the objective weight of the indexes more accurately,and it is easy to have the problem that the weight does not match with the actual operation situation.The weighting coefficients cannot accurately reflect the importance and dynamic changes of the operating load of the microgrid at different moments.Thirdly,how the evaluation results can guide the power quality management of microgrid is yet to be further researched.In view of the above problems,the following research is carried out step by step.Firstly,the traditional objective weighting method mainly uses the single data characteristic of dispersion between data to determine the objective weights of indicators,which causes the evaluation weights to be incompatible with the actual operating power quality problems of microgrid under certain special circumstances.The single-node power quality evaluation algorithm of microgrid based on CRITIC method is proposed in this paper.The method uses the correlation coefficient and standard deviation between indicators to determine the contrast strength and conflict of indicators and thus obtain the objective weights of each indicator.The proposed method could take full account of the contrast strength and conflict between indicators and makes effective use of the data.Therefore,the evaluation results obtained by using the two data characteristics to determine the weights are more closely related to the power quality situation in actual microgrid operation.Further,based on the single-node assessment method proposed above,a multi-node assessment method based on dynamic coefficients is proposed to evaluate the power quality of multiple nodes of the microgrid and determine the power quality problems and their severity of the whole microgrid.The method assigns different coefficients to the evaluation weights according to the influence of loads of different capacity levels on the evaluation results,and the coefficients change with the changes of loads.The method realizes the power quality assessment of multiple nodes of micro-network,and the assessment result is adjusted in real time with the change of load,and the size of coefficient reflects the importance of load,which reflects the real-time change of power quality of micro-network more objectively.Finally,the power quality assessment method of the microgrid is combined with the inverter control of the microgrid.Through the power quality assessment of the microgrid,the main power quality problems in the microgrid and the nodes with serious power quality problems are located,and the control mechanism of the inverter is adjusted according to the power quality assessment results to achieve the overall improvement of the power quality of the microgrid.By setting up a micro-network simulation experiment platform,the effectiveness,accuracy and practicality of the proposed method are verified by using arithmetic examples.The proposed single-node power quality assessment method determines the weights of the assessment indexes by comparing the intensity and correlation characteristics,which is more accurate and objective compared with the assessment results obtained by the traditional entropy weight method.In addition,according to the evaluation results of the proposed method,the power quality problems can be located and then the power quality problems can be targeted for treatment.