The Economic Operation Of Microgrid In The Power Market

With the continued development of China's economic construction, the traditional monopolistic business model cannot meet the requirements of the development of the power industry. For that reason, the world are vigorously promoting the reform of the electricity market and introduce competition mechanism. On the other hand, the traditional centralized model of power supply cannot meet the demand for electricity of national production and life, coupled with increasing pressure on global energy issues and the environment. And Distributed Generation(DG) technologies get born at the very moment, which take good advantage of renewable energy source in generating and improve energy efficiency greatly. But the stability of large power grid shall be adversely affected when a single DG gets parallel running. To solve this problem, domestic and foreign experts propose microgrid. With the help of micro-grid energy management, DGs get operated in a manner coordinated with the distribution network.Different distributed generations constituting microgrid are introduced, their technical characteristics get analyzed, and their power characteristics get modeled mathematically. The output models of wind power and photovoltaic power get built based on statistical models of wind, light and other natural factors. According to the principle of ordering power by heat, the lower limit of micro-turbine's output is determined through cogeneration system analysis. The constraints of the battery charging and discharging process get put forward by considering the life of battery.The interaction between micro-grid and power market in the developing process of power industry get analyzed, on the basis of in-depth study of the electricity market. Electricity distributed company implements demand-side management by means of adjusting the electricity prices, which stimulate and encourage the electricity users to change their consumption behavior. And that helps reduce power loss and power demand. As a demand response, microgrid adjusts its trading electricity at peak periods by controlling DGs and energy storage devices effectively. In the realization of their own economic interests, the power fluctuations in distribution grid get improved. By analyzing micro-grid operating costs in the electricity market environment, the mathematical model of microgrid energy management, taking consideration of economic interests in contract periods, get established, where random variables get introduced.According to the concept of the confidence interval, the optimal model based on confidence interval gets proposed and the dealing methods of different random variables are illustrated. After that, the optimization ideas of changeable confidence interval get proposed. Finally, the effectiveness of the optimization method is confirmed by simulation example which proves that the method is able to solve the problem of microgrid energy management under power market environment.