Distributed Cooperative Control And Optimization Of Microgrid Based On Consensus Algorithm

With the development of power technology,new energy has attracted more and more attention.How to use and develop the current distributed energy and realize more efficient and convenient power utilization has gradually become the focus of research in the field of power.Microgrid is a new power system composed of distributed power supply and load,energy storage system and control device,such as wind power generation system,photovoltaic power station and micro gas turbine.In island operation,the distribution of active power and reactive power of distributed generation in microgrid directly affects the frequency and voltage regulation of the system,and determines the stable operation of microgrid.Microgrid usually adopts droop control mode to make all distributed generators participate in power distribution by simulating the power frequency characteristics of generator units,so as to maintain the stability of system frequency and voltage.However,its essence is differential control,so it is difficult to achieve accurate power distribution in microgrid system with multiple distributed generators.Therefore,based on the information interaction of microgrid distributed generation,the average score of distributed generation power can be estimated through the distributed average consistency algorithm,and the secondary control items of microgrid can be constructed to improve the operation performance of the system,realize the accurate distribution of active power and reactive power in each distributed generation,and maintain the frequency and voltage of the system at the rated reference value.In the secondary control,the communication network topology directly affects the convergence speed of the distributed average consistency algorithm,and then affects the dynamic performance of the secondary control of microgrid.Under the background of reactive power distribution of microgrid distributed generation,this thesis focuses on the following problems:Firstly,this thesis introduces the relevant models of photovoltaic power generation,carries out the corresponding grid connection simulation experiments,studies the influence of lighting and other parameters on its power generation,and also establishes the relevant distributed microgrid model.Under this model,the microgrid island operation can accurately distribute the reactive power through droop control reactive power,Therefore,based on the droop control,the consistency theory is introduced as the secondary control of microgrid.The simulation results show that adding the secondary control can make the microgrid realize the accurate distribution of reactive power.Secondly,based on the distributed consistency algorithm,it is found that the evolution speed of reactive power allocation estimation in secondary control is related to the communication layer topology of microgrid.In order to improve the dynamic performance bit index of microgrid secondary control,this thesis is committed to the fast secondary control of microgrid under communication constraints.According to the relationship between the connectivity of microgrid communication network and the convergence speed of the estimated value of system reactive power distribution,using the idea of gradient descent,this thesis designs the minimum communication link optimization algorithm to realize the microgrid secondary control based on the minimum communication cost.From a practical point of view,it greatly saves the cost of communication link,The convergence speed of reactive power is guaranteed.Based on the reactive power sharing problem of distributed consistency algorithm,this thesis further considers the optimal design scheme of microgrid communication link.Under the background that the communication link of the system is fixed,that is,the communication cost is fixed,a topology optimization algorithm is designed to maximize the algebraic connectivity of the communication network structure on the premise of ensuring the communication network connectivity,In order to improve the estimation speed of average power score of distributed generation and improve the dynamic performance of microgrid.