Distributed Economic Dispatch Approach For Microgrid Considering Communication Line Reliability

As a new integrated technology of distributed power generation system,microgrid is the organic unit of future smart grid and one of the important technologies to solve the future energy and environmental problems.Among them,microgrid economic dispatch is the key technology of microgrid operation control.At present,the microgrid mainly adopts a centralized method to solve the economic dispatch problem.As the penetration rate of renewable energy and energy storage further increases,microgrid systems may face problems such as large information traffic,network congestion,and single-point-failure.In contrast,distributed control methods have received widespread attention because of the small amounts of information,effective overcoming single-point-failure,and adaptability to plug and play.Based on the distributed control method,this paper studies the economic dispatch of microgrid,the main contents are as follows:(1)A distributed economic dispatching method based on first-order consensus algorithm is constructed.Firstly,based on graph theory and probability theory,the communication network and communication line packet loss are modeled.Then,combined with the first-order consensus algorithm,a distributed economic dispatching algorithm for microgrid economic dispatching is proposed.Finally,a case study is carried out on the basis of a 6-node ring microgrid.The simulation results show that the incremental cost and the micro-source output can converge to the optimal solution under the ideal communication line.In addition,the impact of communication line packet loss on the algorithm convergence is analyzed.(2)A fault-correction adjustment mechanism based on similarity measurement method is proposed.In order to overcome the impact of communication line packet loss on the distributed economic dispatching algorithm,based on the Manhattan distance method,an adjustment mechanism is designed for the state variable including incremental cost and power mismatch estimate in the distributed economic dispatching algorithm.When the packets losses occur,the estimated value of the state variable of neighboring agents is obtained through the adjustment mechanism,thereby effectively reducing the impact of packet loss on the algorithm.(3)A distributed economic dispatching method based on robust ratio consensus algorithm is proposed.Based on the robust ratio consensus algorithm that it has the characteristics of robustness to line packet loss,and combined with the idea of virtual buffer in the algorithm,the distributed economic dispatching algorithm is improved.The virtual buffer variable of state mismatch estimate is added to the algorithm to design a robust distributed economic dispatching algorithm.(4)Based on the Siemens Benchmark low-voltage microgrid system,the simulation of robust distributed economic scheduling algorithm are provided.The Siemens Benchmark low-voltage microgrid test system was constructed,and four typical test days were selected.For the three hours of the typical day,the fluctuations of output of photovoltaic and wind systems,and loads were taken into consideration,as well as the different packet loss rates of the communication lines,plug and play scenarios etc.,to verify the effectiveness of robust distributed economic dispatching algorithms.The simulation results show that the robust distributed economic dispatching algorithm can converge to the optimal solution under packet loss of the communication line,thereby verifying the effectiveness of the algorithm.