| With the increasing use of the fossil fuels,the global energy crisis and environmental problem become severer,so it tends to be popular to utilize renewable resources and optimize electrical energy structure.The distributed generation(DG)technology supports the high efficient use of renewable energy resources.Because of the intermittency of renewable resource generation,the disorderd access will affect the safe and stable operation of main grid.Thus,the microgrid(MG)concept is put forward.MG,regarded as an effective management way of DGs,promotes the penetration of renewable resources and mitigates the impacts of renewable resources on main grid,which is significant for solving the global energy crisis and environmental problem.The distributed characteristics of MGs reduce the risk of system operation and dispatch,and improve the stability of system.But,numerous DGs and their intermittent and fluctuating outputs make the operation and control harder for MGs.Also,the low inertia of MGs and the bidirectional power flow will bring challenges for the dispatch of MGs.To realize the economic operation and optimal dispatch,this paper investigates the economic operation with minimal generation cost method and the optimal dispatch with demand response method.Firstly,based on multi agent system(MAS),the two-layer control model is proposed,and the equal incremental cost criterion is adopted to realize the economic operation with minimal cost of MG.Next,the demand response and dynamic price mechanism is introduced and dynamic price based MG optimal dispatch method with demand response is proposed to maximize the user-side payoff and minimize the operation cost of the generation side.Lastly,the digital simulation platform is established in Matlab/Simulink,and the economic operation and the optimal dispatch methods get verified,respectively.The main contents of this paper include the followings:(1)MAS based MG economic operation method.Faced with the islanded MG with lots of renewable resources,this paper proposes MAS based two-layer economic operation model,which consists of the lower layer for the electricity transmission and the upper layer for the information transmission.Then,the construction rules of communication network are given.The common method to derive the distributed control laws based on any arbitrary communication network is proposed.Through getting the consensus of incremental cost of DGs,the economic operation with minimal cost of MG is obtained.Further,the convergence of the distributed control laws is verified theoretically,which guarantees the system power balance during the iterations.Lastly,the effectiveness of the proposed two-layer method gets validated in the simulation platform.The simulation results show that with the fluctuation of the renewable resources and load demands,the proposed method can realize the minimal operation cost of MG.(2)Dynamic price based MG optimal dispatch method with demand response.On the basis of the minimal operation cost of the generation side,to maximize the payoff of the user-side,this paper proposes dynamic price based MG optimal dispatch method with demand response.Firstly,the dynamic price mechanism is proposed,which can maximize the penetration of renewable resources,and decrease the outputs of fossil fuel generator(like microtrubine).Combined with dynamic price and demand response,the optimal dispatch model of MG is proposed,to obtain the optimal participating amount of flexible loads,and ensure the maximal payoff of user-side.At the same time,equal incremental cost criteria is used to minimize the operation costs on generation side.Lastly,in order to test the effectiveness of the proposed method,the MG optimal dispatch with demand response simulation platform is established.The simulation results show that dynamic price based MG optimal dispatch with demand response method not only improves the payoff of the user-side,but also ensures the minimal operation cost of the generation side.(3)Economic operation and optimal dispatch of islanded MG simulation platform.To test the effectiveness of the economic operation and optimal dispatch method,the simulation platform is established in Matlab/Simulink.Firstly,the models of microturbine,windturbine,photovoltaic and energy storage system are established.According to the characteristics of different DGs,different control modes are adopted,among which,the micro turbine adopts the constant power(PQ)control,the wind turbine and photovoltaic adopt maximum power tracking point(MPPT)control,and the energy storage system adopts voltage frequency(V/F)control.Then,a radial islanded MG including four types of DGs is established.Meantime,a corresponding multi agent system based communication network is established.The simulation platform built in this paper not only implements various distributed control strategies,but also satisfy the needs of economic operation and optimal dispatch with demand response. |
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