Research on Reactive Power Impact and Optimization of Photovoltaic Power Distribution Network Based on the Concept of Power Flow Direction Change

With the development of the national economy, the distribution network equipment has been continuously upgraded and the operation level has been continuously improved, and the distribution network has gradually developed in the direction of automation, forming an active distribution network with high penetration, high reliability and self-healing rate of distributed power sources. However, the large-scale access of distributed photovoltaics in the active distribution network often leads to problems such as voltage fluctuation, harmonic over-limit and power factor reduction in the distribution network, which has a great impact on the power supply quality of the distribution network. Among them, the reduction of the power factor of the distribution network will lead to an increase in line loss, a decrease in voltage, and a decrease in equipment utilization, which is extremely detrimental to the power quality of the public grid. Based on the actual situation and operation data of distributed photovoltaic in distribution network of XC District, a city in Shandong Province, this paper conducts a practical study on the impact, causes and improvement measures of low-voltage distributed photovoltaic reactive power in active distribution network. Firstly, according to the actual operation of distribution network, the concept of transformer power flow direction change point (stage) is proposed. Then, based on the concept of transformer power flow direction change point (stage), this paper studied the impact of public transformer distributed photovoltaic access on power factor using a large number of operating data, and deeply analyzed the reasons for the reduction of power factor of public transformer connected to distributed photovoltaic through vector method, and then proposed a transformer refined reactive power compensation scheme based on intelligent fusion terminal of distribution transformer. Finally, this paper proved the correctness and scientificity of the research methods and results through an engineering reconstruction example.