Research On Resilience Improvement Strategy Of Distribution System Based On Virtual Energy Storage

Serious large-scale blackouts will occur in the distribution network under extreme events,which will directly affect the reliability of the user power supply.Improving the resilience of the distribution system to resist extreme disasters,reduce fault losses and restore power supply as soon as possible has become a hot spot of common concern for scholars at home and abroad.Virtual energy storage(VES)can guarantee the continuous power supply of key loads after extreme events by aggregating flexible resources such as mobile energy storage and demand response,which is an effective technical means to improve the resilience of the distribution system.However,at present,the optimal scheduling of VES is modeled and optimized in the form of discrete time points.It can only obtain the state of charge of a certain time section of VES,and it is difficult to accurately capture the operating state of VES in this time section.When extreme events occur,it is easy to cause problems such as imbalance between supply and demand and increased fault losses.Based on this,this paper proposes a resilience improvement strategy for the distribution system based on VES’s continuous operation.The specific research contents are as follows:Firstly,aiming at the problem of VES energy state evaluation in any closed interval,the definition and related properties of normalized Bernstein polynomials are derived by normalizing the operating variables.A continuous approximation method of interval normalized Bernstein polynomials is proposed,and a VES continuous operation model based on interval normalized Bernstein polynomials is constructed.Secondly,aiming at the problem that VES operation based on discrete time points is difficult to effectively improve the resilience of distribution network,by studying the coupling relationship between power network and transportation network,a mobile energy storage path planning mechanism based on shortest path is proposed.According to the interval normalized Bernstein polynomial,a resilience improvement strategy of distribution system based on VES continuous operation is proposed.The example analysis shows that the proposed resilience improvement method is effective in reducing load loss and operating costs.Finally,aiming at the operation and maintenance cost sharing problem of VES participating in the resilience improvement of distribution system,based on the cooperative game theory,a VES operation and maintenance cost sharing strategy based on nucleolus allocation method is proposed.On this basis,by constructing a proportional allocation model and a Shapley value allocation model,the effectiveness of the nucleolus allocation method in VES operation and maintenance cost sharing is discussed in detail from three aspects : allocation efficiency,allocation fairness and allocation rationality.The results show that the proportional distribution method has high computational efficiency,but the fairness and rationality of distribution are insufficient.The Shapley value distribution method can reflect the fairness of distribution,but it cannot guarantee the rationality of distribution to the greatest extent.The nucleolus distribution method can effectively balance the fairness and rationality of distribution,and is more convincing in the sharing of VES operation and maintenance costs.