Research Of The Distributed Synergetic Control Strategy For Microgrid

Due to the low cost,environment-friendly and high efficiency,distributed generation(DG)has received increasingly attention of the world.However,the utilization of small DGs is limited because of the fluctuation and intermittency in primary energy.Microgrid(MG)is a cluster of different DGs,energy storage system,loads and electric vehicles,which can provide reliable and high-quality electric power.In MG,most DGs connect to the grid through the power electronic converter,which have the characteristics of fast response and low inertia.As a result,the control strategy of MG needs to take into account the coordination of distributed resources in different time scales.Due to the requirement of complex communication network,the traditional centralized way cannot meet the application of distributed resources.Appoint to these problems,the distributed synergetic control strategy of distributed resources is proposed in this paper.Under the constraint of system stability of MG,the power quality of frequency and voltage,energy optimization control strategy are given in this paper.Moreover,the synergetic stability control strategy is proposed.In this paper,a distributed synergetic control based on multi-agent systems is proposed to solve the problems of frequency and voltage errors,system stability and power sharing accuracy in the traditional droop control of microgrid.Starting with power flow equations,we build the secondary-order dynamic model of microgrid,which consist of three parts—1)active power allocation,2)active power-frequency,and 3)reactive power-voltage droop control.Considering time-delays in communication network,the synergetic control algorithm with leaderless is proposed to allocate the active power in inverse proportion to the droop coefficient,and the synergetic control with a virtual leader is proposed to control the system frequency and voltage to keep at the expected value.Besides,the extended Lyapunov theorem is introduced to verify the globally asymptotical stability.Moreover,the impacts of communication disturbance is also discussed from the aspects of control precision and system stability.A multi-stage fuel consumption minimization in an islanded voltage source converter-based MG.At the upper layer,a first-order consensus protocol is applied to calculate the active power to minimize the total cost.At the middle layer,based on the secondary-order model of active power regulation,a novel consensus protocol is proposed to make the DG export the reference active power given in the first layer.At last,the secondary-order consensus protocol is used to adjust the droop parameters adaptively so that the system frequency and voltage is near at the expected.The control algorithms at each stage are distributed.The MG is globally asymptotic stability under the proposed control strategy through the analysis the direct Lyapunov method.To improve the stability of MG,an auxiliary controller is proposed to increase transient stability of virtual synchronous generator,which can be used to suppress the disturbance.Under the analysis of the operation and control mode of the conventional synchronous generator,a distributed stable controller is designed is proposed based on the distributed synergetic control.In the proposed controller,each DG can adjust its control parameters adaptively,and the MG has strong robustness.