Research On Optimal Dispatch Of Active Distribution Network Considering Risk Of Over-limit

With the increasingly serious environmental pollution problem and the rapid development of the power industry,it is imperative to research and promote the green and renewable power generation technology.The large-scale access to the distribution network of distributed generator helps to improve power quality and power supply reliability,reduce network losses caused by long-distance transmission of power,and also improve the overall economic benefits of the distribution network.In order to improve the adaptability and capacity of the distribution network for large-scale distribution generator access and ensure the optimal operation of the grid as a whole,the concept of active distribution network came into being.The operation of large-scale renewable distributed power supply is random and intermittent,and its access changes the power flow distribution of active distribution network,resulting in the possibility of overvoltage and line blocking in the process of system operation,which brings challenges to the safe operation of active distribution network day-ahead scheduling.The research on the risk of the traditional distribution network is based on the establishment of the component outage model caused by the fault and the establishment of the system blackout risk index.In the active distribution network,with the access of the large uncontrollable distribution generator,the uncertainty of the uncontrollable distribution generator output is required.Consider the operational risks that the system brings.In order to realize the optimal dispatch operation of active distribution network,coordinate the management of various controllable resources within active distribution network,and properly handle the impact of the uncertainty of renewable distributed power output on the system.The study of the risk of exceeding the limits brought by the uncertainty of distribution generator output is very important.In this paper,the conditional value-at-risk theory is used to construct the voltage over-limit and tidal limit risk assessment indicators,and the active distribution network optimization scheduling model considering the conditional risk value safety constraints is established.Under the premise of ensuring the economic operation of active distribution network,ensure and evaluate its safety,at the same time evaluate and control the operational risk of the active distribution network through a reasonable active distribution network scheduling strategy.Firstly,this paper introduces the power system risk assessment method and risk index system,analyzes and models the uncertainty of uncontrollable distribution generator in active distribution network,considers the probability distribution characteristics of photovoltaic power source,and establishes the risk assessment index of active distribution network system based on conditional risk value.Secondly,the simulation calculation is carried out on the improved IEEE33 node test system,and the operational risk and operating cost under different confidence levels are compared and analyzed.The results show that the scheduling model considering conditional value-at-risk security constraints can objectively reflect the system operation risk,control the system risk within the allowable range,and guarantee the safe and economic operation of the active distribution network.Finally,the model proposed in this paper is verified based on the actual operation data of an active distribution network in a north city.The results show that the proposed active distribution network optimization scheduling scheme and ideas considering the conditional value-at-risk security constraints are correct,the system can be guaranteed to operate safely,and the validity and versatility of the verification model and scheduling strategy.