| With the emerging technology for distributed generation and urge of improving quality of service of power supply for energy users,more and more Microgrids(MG)are integrated into the distributed networks to serve the energy users.These Microgrids are gradually formulating a Multi-Microgrid System(MMGS),which will play an important role in the future energy supply.The centralized control and operation of MMGS may rise many issues since the distributed MGs are owned by different market entities.In addition,building a centralized control center not only increases the expense of investment,but also brings the issues of maintaining fairness among energy users.From the social level,adding an additional organization may cause many problems.Therefore,"decentralization" of energy supply is a more feasible solution for future energy supply.In this paper,we focus on the indispensable part of the energy supply "decentralization"-the transaction mechanism,carry out research,and propose a multimicrogrid decentralized transaction scheme based on blockchain technology.First,a peer-to-peer(P2P)energy trading strategy was designed based on auction quotation,and the entire matching transaction process was divided into two stages: quotation and clearing.In the quotation stage,each microgrid publishes its own transaction information to determine the role of the microgrid in selling or purchasing electricity.For the electricity sales priority of the electricity sales type microgrid,a unified weight clearing algorithm(UWCA)is designed and sorted on the basis of comprehensive consideration of environmental and power generation scale factors to form an energy sales unit sequence SESU.On the basis of considering the economic benefits of the multimicrogrid system,the energy purchase unit sequence SEBU formed by the power purchase type microgrid is determined by decreasing bid price algorithm(DBPA).In the clearing phase,according to the sequence of sales units and purchase units formed by energy,the middle market rate model is used to match the transaction objects.The comparison between auction-based P2 P trading strategies and traditional trading strategies shows that the cost reduction rate of P2 P trading strategies can be up to 40%.Secondly,the application of the underlying technology of the blockchain to multimicrogrid transactions is studied,the transaction mode based on the blockchain technology is designed,and the asymmetric encryption algorithm is applied to the information transfer process between microgrids to ensure the authenticity of information,and the smart contract technology is applied to the energy transfer process after the transaction is concluded to ensure the automatic forced transfer of energy,and a laddershaped transaction cycle structure is designed between the matching phase and the execution phase.According to the UTXO transaction model and account model,a multi-microgrid system energy credit account model is designed.To further solve the problem of distributed microgrids' consensus on transaction schemes,an evaluation mechanism based on factors such as bookkeeping,quotation,declared power,information interaction speed,power quality,etc.was designed.Based on the improved practical Byzantine fault-tolerant algorithm,the evaluation mechanism is introduced into the consensus process,a consensus algorithm based on evaluation is designed,and the effectiveness of the proposed consensus mechanism is verified by an example.Finally,in order to realize the proposed trading strategy and consensus algorithm,a trading mode based on Hyperledger Fabric is designed,and use Vmware Workstation14 Pro virtual machine to configure Linux Centos7 operating system to deploy Fabric1.1 network simulation to realize the P2 P transfer operation,thus verifying the operability of the P2 P transaction based on Fabric network.At the same time,in order to ensure the feasibility of the transaction scheme,the line is checked for safety based on the power transmission factor.For the line that exceeds the limit of the power flow,the power transmission factor is used to determine the power contribution of the microgrid and the congestion management price.A distributed congestion management method for adjusting microgrid quotations through congestion management electricity prices is designed and a method of "preempting transmission channels" is proposed.Finally,a simulation example verifies the proposed congestion management scheme.The results show that the proposed distributed congestion management method can effectively solve the problem of line congestion. |
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