Comparison of Fuel-saving Effect Between Heat Accumulator and Electric Boiler Used for Wind Power Accommodation in CHP Plant

Abstract

The combined heat and power (CHP) units operating under the principle of ‘electric power determined by heat load’ is a main reason for the serious wind power curtailment problem during heating season in Northern China. Allocating heat accumulator or electric boiler to CHP unit are two effective measures to partly decouple its power output from heat output in order to enhance the flexibility and peak regulation ability of the unit for wind power accommodation. This paper mainly focuses on the analysis and comparison of fuel-saving effect between these two measures when used for 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, and the fuel consumption characteristic of it, the changes in operation mode after allocating heat accumulator or electric boiler to extraction unit are analyzed, and the expressions for the quantity of the saved fuel due to more consumption in wind power are given. The fuel-saving effect of these two measures are compared theoretically, and case studies based on an optimal dispatch model for joint operation of wind farm and CHP plant are presented to verify the conclusions drawn from theoretical analysis. The research in this paper can provide certain support for the selection between these two measures, and for the formulation of relevant policies for wind power accommodation.