Abstract: The access of high proportion distributed power sources leads to problems such as voltage fluctuations,increased harmonics,and decreased power factors in the distribution network,which seriously affects the power supply quality. The traditional governance method is prone to over compensation for switching and under compensation for non-investment,and the actual application effect is not ideal.In order to solve the above problems,based on the operation data of distributed photovoltaic in the actual distribution network of a prefecture-level city in Shandong,substantive research were conducted on the reactive power impact,causes and improvement measures of low-voltage distributed photovoltaic in active distribution networks.Firstly,according to the actual operation status of the distribution network,the concept of phase change of transformer power flow was proposed,and a large amount of operating data was used to study the influence of the access of public transformer distributed photovoltaic on the power factor.Then,the reasons for the reduction of power factor after the public transformer is connected to photovoltaic were analyzed through the vector method,and a refinement reactive power compensation scheme for transformers based on intelligent fusion terminals of distribution transformers was proposed. Finally,through the example of engineering transformation,the power factor of the public transformer in the case of photovoltaic access was effectively improved,which proves the correctness and effectiveness of the method and research results proposed.