Research On Finite-Time Consensus-Based Distributed Coordination Control For Multi-Microgrid Systems

Low-carbon electricity under Double Carbon Goals is facilitating the development of the new power system with high-proportion of renewable energy.And how to reduce the impact of large-scale distributed generation(DG)accessing is a key issue.By integrating DGs,energy storage,and load locally,the microgrid(MG)has become known as the most effective vehicle by managing DGs.Multiple adjacent MGs can be interconnected to form a multi-microgrid system,thus the utilization of renewable energy and the operational reliability are improved through mutual power support among MGs.Nevertheless,the control of a multi-microgrid system is more difficult than that of a single MG,since there exists more complex power and information interaction between MGs.The multi-agent consensus algorithm,which makes the state of agents converge to a common value through the communication between agents,provides a feasible method to coordinate a multi-microgrid system.In this paper,the distributed coordination control for multi-microgrid system based on finite-time consensus algorithm is studied from the aspects of system modeling,theoretical analysis,strategy design,and simulation in islanded AC multi-microgrid.The main contents are as follows:(1)Multi-agent-based distributed control structure for multi-microgridA multi-agent-based distributed control structure for multi-microgrid is proposed,which establishes the correspondence between the multi-microgrid system and the multi-agent system.Based on graph theory,the mathematical model of the inter-agent communication network is established.The communication network includes inter-MG subnetwork and intra-MG subnetworks,in which MG agents(MAs)exchange information on inter-MG subnetwork while DG agents(DAs)exchange information on intra-MG subnetworks.Control actions are performed in a distributed manner through sparse communication among agents,which overcomes the shortcomings of centralized control and decentralized control.(2)Finite-time consensus-based distributed control strategy for multi-microgridThe distributed coordination control strategy for multi-microgrid includes primary droop control,frequency/voltage secondary regulation and tertiary economic dispatch,where the tertiary economic dispatch includes economic dispatch among MGs and economic dispatch within MGs.Based on the droop formula,DAs obtain the frequency/voltage correct item and calculate the optimal outputs for DGs through consensus iteration,so as to realize frequency/voltage secondary regulation and economic dispatch within MGs;MAs coordinate the power supports among MGs and calculate the optimal outputs for MGs through consensus iteration,so as to realize economic dispatch among MGs.In order to overcome the limitation of traditional consensus algorithm and achieve control objectives within a finite time,an improved fast finite-time consensus algorithm is proposed.The convergence performance of the proposed algorithm proved by Lyapunov theory,La Salle’s invariance principle,and finite-time stability theory.The simulation results validate the effectiveness of the proposed strategy and demonstrate that the proposed algorithm can accelerate convergence speed and has good anti-interference performance.(3)Participation factor-based robust economic dispatchMost existing economic dispatch schemes are implemented based on forecast,which assume the load/renewable energy power to be a invariant value within a certain dispatch period,rarely consider how to maintain the effectiveness of dispatch schemes under uncertainties.Therefore,a robust economic dispatch scheme for multi-microgrid based on participation factor policy is proposed.Considering power support among MGs,the economic dispatch model is established,and the optimal outputs of DGs and MGs are obtained by consensus algorithm.Based on the optimization results,the outputs of controllable DGs is dynamically adjusted according to their participation factors in the presence of load/renewable energy fluctuation.Each MG absorbs its own fluctuations so that the power support among MGs is not affected and the robustness of dispatch scheme against uncertainties is improved.The simulation results show that the proposed dispatch scheme still maintain good optimization performance when load/renewable energy fluctuates.