Micro-grid-based Electricity Market Transactions And Economic Operation

Micro-grid is composed of a variety of distributed power, with renewable energy as its main resources. Its attractive advantage is low cost, low voltage and low-pollution and so on. And, Micro-grid is available to integrate the advantage of a variety of distributed generation and coordinating the contradiction between the distributed system and the main grid. In this case, different resources with diversified characteristics have been utilized efficiently, so Micro-grid becomes a hot issue worldwide in recent year. However, with fast increasing of installed capacity of these distributed generations, power surplus in a micro-grid becomes an urgent problem to be solved, which means that there is excess power output except power consumption by the local users. One of solution is let these micro-grids participate in electricity market based on main grid. Considering the fact that Micro-grid have not the ability to bid with the conventional energy, this paper analyzes power biding among Micro-grids under the electricity market. After Micro-grids into electricity market, anyone of micro-grids would act as independent power producer. Like other roles in the market, the Micro-grid has its inherent incentive to maximize profits. As we known Micro-grid is composed of active low-voltage power distribution system, its scale is not large in its capacity. To get the best profit, Micro-grid bidding in electricity market and dispatching its generators in economic mode are needed.Firstly, after discussing the necessity of constructing a micro-grid electricity market, MAS-based auction model of micro-grid electricity market is proposed. In this model, the system is with hierarchical structure, having real-time control and biding function. Moreover, the role of each agent in micro-grid is designated. Considering that Micro-grids electricity trading volume is small and unsteady, so, they are only allowed into real-time market at now.Secondly, for micro-grid, mathematical model of bidding strategies on the basis of game theory is proposed. In this model, market factors such as bidding behavior and electricity prices are considered. An example is used to verify the availability to get bidding strategy for Micro-grid.Thirdly, economic dispatch among distributed generators is discussed once the Micro-grid has obtained its bidding power. Also, based on understanding the characteristics of every kind of distributed generation, mathematical model of economic dispatch in the Micro-grid is proposed. By comparing the advantages and disadvantages between improved PSO algorithm and standard PSO algorithm, hybrid PSO algorithm with improved linear decreasing weight is adopted to calculate the solution. And a programming with Matlab is designed.Based on the above research, a perfect solution that Micro-grid is expected to maximize the economic benefits when there is excess power surplus is obtained.