Multi-Grade Energy Trading In Distribution Side Considering Heterogeneous Distributed Generation And Demand Flexibility

Recently,the penetration of distributed energy resources(DERs)grows constantly,which gives rise to the voltage violations and distribution line overload in distribution networks(DNs)and thereby posing challenges to the accommodation of distributed renewable energy.Promoting peer-to-peer(P2P)energy trading between DERs and customers in DNs is an important way to realize the local accommodation of distributed renewable energy.However,the existing electricity trading mechanisms fail to take the heterogeneity in power generation and demand flexibility into account,thus can’t fully encourage the enthusiasm of flexible demand to accommodate DERs.Therefore,it is imperative to establish a P2P energy trading mechanism that incorporates the heterogeneity of distributed energy resources and demand flexibility.This paper aims to encourage the flexible demand to locally absorb the uncertainty of distributed renewable energy so as to improve the utilization efficiency of DERs,which expedites the pursuit of the goal of the emission peak and carbon neutrality.The study of our research is outlined follows:This paper proposes a multi-grade energy trading model considering the power supply reliability and demand flexibility for efficient accommodation of DERs.The reliability level of distributed power supply and the flexibility level of customers are evaluated to obtain the credibility assessment value for various DERs.A multi-grade energy trading model considering the credibility assessment value is established to match different types of demand with the corresponding grades of energy.A distributed market clearing mechanism for P2P energy trading is established using the alternating direction multiplier method(ADMM),which can effectively preserve the privacy and decision autonomy of individual participants.Simulation results show that the proposed method can reduce trading risks while improving the DER producers’ profits and customers’ benefits by 20.2%and 5.2%,respectively.To substantially improve the computational efficiency of the proposed P2P energy trading model,this paper proposes a bisection-based fast solution method for energy trading.The KKT conditions of the DER producers’ model and customers’ model for P2P multi-grade energy trading are obtained with Lagrange multipliers.Then,this paper combines the complementary slackness characteristics of KKT conditions with the bisection method to develop a fast solution method to solve the optimal energy procurement of consumers.Furthermore,closed-form solutions to the DERs energy allocation problem are derived based on the complementary slackness conditions,which enables fast pricing of DER producers.The simulation results verifies the outstanding merits of the proposed fast solution method in aspects of accuracy and efficiency in solving the multi-grade energy trading problem in large-scale distribution system such as IEEE 8500-node distribution feeder.To deal with the operational security verification of the DNs with P2P multi-grade energy,this paper proposes a distributed operational security verification method considering the full spectrum of power sources,network and end-use customers.First,this paper proposes a centralized verification method considering the loss of DER producers’ profits to ensure the secure,economical and reliable operation of the DN through the adjustment of reactive power and network reconfiguration.Furthermore,a distributed operational security verification method considering the loss of the DER producers’ profits,the network loss of the distribution network and the loss of customers’benefits is developed,which is beneficial for the loss reduction and preserving the privacy as well as decision autonomy of individual trading entities.Simulation results show that DN reconfiguration can remarkably reduce the power loss using the centralized security verification operation.The total loss is reduced by 34%using the proposed distributed operational security verification method compared to the centralized operational security verification method.In summary,this paper focuses on multi-grade energy trading mechanism in DNs.This paper further investigates the solution method of the trading problem and the impact of energy trading on the operation of DNs,so as to achieve the efficient accommodation of DERs while ensuring the operational security of the DNs.