Risk Assessment Of Distribution Network Considering The Uncertainty Of Photovoltaic Power Output

With the development of photovoltaic power generation,the penetration of photovoltaic power generation in distribution networks is also increasing.Photovoltaic power generation is affected to a great extent by environmental,meteorological,and other uncertainties.The volatility of its output under high-permeability scenarios has caused a series of adverse effects on the operational safety of distribution networks.The safe operation of the distribution network is not only related to the power system itself,but also related to the user's personal and property safety.Therefore,the risk assessment of the distribution network under the scene of high-permeability photovoltaic generation,quantify the operational risk level of the distribution network,and take reasonable measures for risk control.This has practical significance for improving the safety of distribution network operation and ensuring the quality of power supply for users.Based on the probabilistic risk assessment theory,this paper studies the risk assessment methods for distribution networks containing photovoltaic power generation and the operational risk control methods based on active distribution networks.The main tasks are as follows:This paper establishes operational risk assessment indicators for distribution networks containing photovoltaic power generation.Without considering the fault within a short period of time during the operation of the system,the fluctuation of the photovoltaic power output may cause the voltage of the system to exceed the limit and the limit of the flow of the branch.Therefore,the paper establishes the node voltage limit and branch flow current limit is severe.Degree function,which in turn generates risk indicators.Based on the principle of correlation analysis and Bayesian network theory,a photovoltaic power generation probability prediction model based on data correlation analysis was established.The accuracy of the model's probabilistic forecast results was validated by an example of an actual photovoltaic power plant.This paper studies the risk assessment method for distribution network containing photovoltaic power generation.Based on the probabilistic prediction results of photovoltaic power generation output,Mont Carlo method is used to calculate the probability density curve and cumulative probability distribution curve of node voltage and branch power flow;the probability of node voltage over-limit and branch flow over-limit is calculated according to the curve,and the degree function gets the corresponding severity;Finally,according to the risk formula,the risk value of the system is calculated.The analysis of the risk assessment results shows that the higher the penetration rate of photovoltaic power generation in the system,the greater the system risk.This paper establishes a mathematical model for operational risk control of distribution networks containing photovoltaic power generation.According to the principle of maximum photovoltaic consumption,the objective function with the goal of maximum photovoltaic power output and relatively low risk is determined.The corresponding weight coefficient is set to control the risk level,and node voltage constraints,branch power flow constraints,power balance constraints and photovoltaic power capacity constraints are also considered.The improved particle swarm optimization algorithm is used to calculate the optimal output of the photovoltaic power supply,and the system risk is controlled within the allowable range.