Research On Heat-electricity Combined Scheduling Method Of Peak Load Regulation Based On Boiler In The Secondary Heat Supply Network

The power grid of the "Three North" area is mainly constituted by coal-fired units while flexible peaking power, such as hydropower, gas and fuel oil, is severely lacking. Due to the heating demand, cogeneration units occupy a large proportion in the coal-fired units. So in the winter night, it is extremely difficult for peak load regulation and leads to serious phenomenon of abandoned wind power because of the high power output of cogeneration units according to heat determining power as in the peak period of thermal load, valley period of electrical load and blow period of wind power.In order to consume abandoned wind, the paper puts forwards the heating scheme that adds peak-shaving electric boiler in the secondary heat supply network, which is also called heat exchange station. Based on the heating system, it does a comprehensive and systematic study on start and stop control mode of peak-shaving electric boiler, heat balance of heat supply network, electricity-heat combined scheduling of the whole system and economical efficiency of the scheme.Firstly, based on analyzing the mechanism of abandoned wind phenomenon in the "Three North" area, a consuming abandoned wind scheme, which adds peak-shaving electric boiler in the secondary heat supply network, is proposed. On the basis of heating system, the paper researches the start and stop control mode of electric boiler and the heating characteristics of cogeneration units. Then it sets up the heating balance equation of primary and secondary network.Secondly, in the light of the heating balance equation of heating system, the paper constructed a new scheduling model with taking coal consumption as the objective function. In the new scheduling model, the electrical load is balanced by the whole network units while the thermal is balanced by the cogeneration units and peak-shaving electric boilers. Furthermore, the new scheduling model also considers the relationship between lower and upper power limit of cogeneration units and extraction volume as well as the punishment of abandoned wind power. According to the characteristics of multi constraints equation, changeable lower and upper bound of inequality constraints, it introduces penalty function and constraint self-regulation based on the elementary particle swarm optimization. Then the paper apply improved particle swarm algorithm to solve the optimized model of heat-electricity combined scheduling.Next, on account of case analysis, the paper studies the mechanism of consuming abandoned wind power of the scheme with peak-shaving electric boiler in the secondary heat supply network. Besides, it research es the influence of regulation scheme and capacity of electric boiler in heating network to the coal consumption and abandoned wind power.Finally, from the economic aspect, the paper studies the feasibility of scheme with peaking-shaving electric boiler in the secondary heat supply network. It regards feed-in tariff and heating earnings as income while depreciation and operating expenses of electric boiler, electric charge of electric boiler and consumption of coal as costs. Then a profit calculation model is established for the combined heat and power dispatching system. Meanwhile, the critical price of the scheme is calculated, and the effect of electricity price in the demand and generation side to profit is taken into consideration.The research and results of example analysis show that the scheme, which adds peaking-shaving electric boiler in the secondary heat supply network, can optimize the electric load curve the whole system provides and the thermal load curve the cogeneration units supply. The scheme also decreases the heating peak of cogeneration units and electric output of heat determining power while increase the electrical load valley of grid at the same time, which offers more space for wind power and improves the absorptive capacity of wind power.