The issue of real-time deep down-regulation ancillary service has received increasing attention in the Northeast of China. Participation of combined heat and power plants with multitype units and flexible heating devices in the market is investigated. This paper establishes a model of feasible operating region and the coal consumption function for the combined heat and power plant. An internal optimal dispatch model and the minimum overall electric power output model for the plant satisfying a given heat load are presented. Furthermore, the models of total cost for down-regulation and average cost for deep down-regulation in two levels are established. These models are validated based on the realistic data of the plant in the Northeast of China. In case studies, the influence factors and change rules of the minimum electric power output, the total cost, and the average cost of plants are analyzed.Energies 2020, 13, 787 2 of 17 in real time and how to formulate a bidding strategy for CHP plants in the DDR market based on these parameters need to be further studied. Especially when a plant contains different types of units, the problem becomes more complicated.At present, many studies have been reported in the literature related to the issues of "decoupling power and heat" of CHP plants to improve the flexibility from different perspectives. At the system level, the main concerns are the impact of the decoupling on integration of renewable energy, energy consumption and emissions [3-5], national economy [6], and centralized dispatch operations [7] after the decoupling. At the power plant level, the main concerns are the impact of decoupling technology [8], operational flexibility evaluation [9][10][11][12], operational strategies and economics [13][14][15][16][17]. However, in the context of the Northeast China DDR market, there is little literature on the operational strategies of CHP plants after the decoupling. Only one of them [16] studies the bidding strategy of plants with extraction condensing units and HA through predicting the behavior of competitors, and obtains very useful conclusions. However, they do not consider multitypes of units and multiple decoupling methods. Therefore, a more general model is necessary. In addition, because the behavior of competitors is difficult to predict, there are many problems in practical applications.Therefore, this paper studies a CHP plant consisting of multitype units and the EB and HA. In the Northeast China real-time DDR market, several general models are established, including the operating constraints of devices in the plant, the coal consumption function, an internal optimized dispatch model of the plant, the model of minimizing the electric power output of the plant, the models of total cost for down-regulation and average cost for DDR. Furthermore, the bidding strategy of the plant participating in the real-time DDR ancillary service market is proposed.
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