Research On Power Quality Analysis Of Distribution Network With Distributed Generation

With the development of economy,science and technology,the large-scale use of fossil energy not only brings great pollution to the global environment,but also intensifies the formation of greenhouse effect.The research and development of new energy technology has become one of the core methods to alleviate energy and environmental problems all over the world.Clean and green energy,represented by wind power and solar photovoltaic power generation,is more and more widely used in the power grid.It has taken solid steps to achieve the grand goal of carbon peak by 2030 and carbon neutral by 2060.Due to the widespread application of distributed power supply,it will not only seriously affect the power quality and system stability of distribution power grid,and can also lead to the power supply structure,operation and management methods have a significant change.So to further analyze the power quality of distribution network is very necessary,there is also a great practical significance.This dissertation first describes the development status of distributed generation at home and abroad.Then the power quality problem generated by the distributed generation is described,focusing on wind power generation and solar photovoltaic power generation as an example to analyze the influence characteristics of distributed power grid on power quality.All kinds of evaluation indexes of power quality are summarized,and the advantages and disadvantages of main evaluation methods of power quality are analyzed.Secondly,based on the distributed power grid to carry on the simulation,analysis and research of its specific impact on power quality,the grid-connected wind power generation simulation system and grid-connected photovoltaic power generation simulation system are set up respectively based on Simulink.They are simulated under different operating conditions,and the relevant power quality index data is obtained.Through analysis and judgment of the data,the influence characteristics and factors of distributed power grid on power quality are summarized.Thirdly,the existing typical power quality evaluation methods are summarized and analysis,and the two kinds of evaluation method are studied based on weighted features.The power quality evaluation method is presented based on the improved entropy method,and the other power quality evaluation method is presented based on the improved analytic hierarchy process（AHP）.Through the example analysis,the two kinds of evaluation method was verified the rationality and practicability.On the basis of the above evaluation methods,this dissertation proposes a comprehensive evaluation method of power quality based on AHP-CRITIC subjective and objective variation coefficient synthetic weighting.An example is given to verify that the proposed method can comprehensively evaluate the power quality of a distributed power grid,which the weight is assigned by the combination of subjective and objective variation coefficients.The results show that the method in this paper considers both subjective and objective factors,and the comprehensive evaluation results are more credible and reasonable.