Study On Electricity Transaction Participation Mechanism Of Microgrid Under Market-oriented Environment Of Electricity Retail-side

As the continuous access of microgrids with different sizes and types to local distribution networks,and the continuous construction and development of elelctricity market,the elelctricity market on the retail-side is presenting a new pattern of diversification of stakeholders.The microgrids have a certain position in the main participants of the electricity market,they can participate in various forms of market competition as a power producer,no longer be limited to the status of only power consumers.But at present,the research on electricity trading method and bidding theory for microgrid connected to distribution network is still in its infancy.This research adapts to the development trend of microgrids and modern distribution system.Based on the combination of economics(e.g.game theory,auction,etc.)and power system theory,the energy management and electricity trading methods of microgrid in market environment are studied.In this paper,a hierarchical energy management method is proposed to coordinate the relationship among market,distribution network dispatching and microgrid controllable units in the market environment.Meanwhile,the price formation mechanism of microgrid participating in electricity trading in electricity retail market,the auxiliary service mechanism of microgrid participating in distribution network and the microgrids’ P2 P electricity trading are focuse of study.The main work includes the following aspects:(1)The price formation mechanism of the electricity transaction between microgrids and distribution network is studied.There are two kinds of market behaviors of purchasing and selling electricity in the retail electricity market for microgrid.At present,the price of microgrid is usually set by the government,which is not conducive to the economic allocation of resources.This paper establishes the purchase and sale model of the electricity market on the retail side and puts forward the theory of dynamic purchase and sale prices.By optimizing the shadow price of the constraints on purchase and sale of electricity,the purpose of maximizing the comprehensive social welfare is achieved.The validity of the model and algorithm is verified by the case study.The results show that the regulation of dynamic purchase and sale price can increase the economic benefits of market participants and increase the average-to-peak rate of distribution network.(2)A hierarchical energy management method based on price signal for microgrid is proposed.Specifically,firstly,a price-based economic operation model is established for the internal units of the microgrid,and the controllable units are scheduled to minimize the operation cost.Then,according to the dispatching results,appropriate control methods are adopted for the controllable units to control the power output and voltage stability.Because DC microgrid represents the development trend of distributed energy supply system in the future,DC microgrid is choosed to study the voltage control method of internal dispatching units.A hierarchical energy management theory including upper layer economic dispatching and lower layer energy control of DC microgrid system is tested in the case study.(3)An innovative market mechanism for distribution network ancillary services with microgrid participation is proposed.Because the penetration of intermittent resources such as renewable energy and electric vehicles at the terminal of distribution network will affect the voltage stability of distribution network node,this paper uses price mechanism to encourage microgrid with energy storage system to participate in distribution network ancillary services,and to suppress some nodes of distribution network.Bertrand price auction mechanism is designed in the market to complete microgrid participation in distribution system voltage stability ancillary services.The numerical results show that the proposed market mechanism of ancillary services is not only conducive to increasing the economic benefits of microgrid,but also conducive to the stable operation of the distribution system.(4)P2P transactions among multiple microgrids are studied based on game thory.Because of the liberalization of the electricity market on the retail side,it is possible to trade electricity between microgrids.In this paper,through the establishment of the microgrid P2 P electricity trading market,on the basis of the proposed trading conditions and rules,the competition behavior of purchasing and selling microgrids are analyzed based on game theory.A game model of Muliti-leaders-follower for both sides of purchasing and selling microgrids.At the same time,purchasing microgrids capture their selection according to evolutionary game theory.The non-cooperative game is used to simulate the price competition behavior of the microgrid.Moreover,the existence of equilibrium is proved and an algorithm for solving equilibrium solution is proposed.The feasibility of the proposed P2 P transaction game model and the fast convergence and validity of the algorithm are proved by a case.Furethermore,the effection of P2 P transaction on the revenue and cost of the microgrids are compared from the economic point of view.