Capacity Allocation of Heat Accumulator in Combined Heat and Power Plant for Wind Power Accommodation

The installed capacity of wind power generation is developing rapidly in China, but at the same time wind power accommodation is still a serious problem. The combined heat and power (CHP) units operating under the principle of ‘electric power determined by heat load’ is the main reason for wind curtailment during heating season in Northern China. Allocating heat accumulator to CHP unit can partly decouple power output from heat output and enhance the flexibility and peak regulation ability of the unit in order to promote wind power accommodation. Based on the relationship between power and heat output of extraction unit, which is the main type of CHP units in Northern China, the operation strategy of extraction unit with heat accumulator to maximize peak regulation capacity is analyzed. A calculation model for the increment in peak regulation capacity is proposed, and the method for optimal capacity allocation of heat accumulator is proposed under the objective of maximizing wind power accommodation. Case studies based on a typical extraction unit in China are provided to show the effect of heat accumulator. Besides, the calculation model for the increment in peak regulation capacity proposed in this paper can be the basis for subsequent capacity allocation research considering economy.