Study On Heating Capacity Of Provincial Electricity-heat Integrated Energy System

In recent years,the problem of wind power and solar power curtailment condition has become more and more serious.In order to solve this problem,China is actively carrying out the flexibility transformation of CHP unit,the existing schemes include: heat storage,electric heating,bypass reconstruction,low-pressure cylinder cut-off.Its essence is to change the traditional CHP unit's “determining electricity by heat” operation mode to “determining heat by electricity” operation mode,that is,to preferentially accept renewable energy and then coproduce heat.If the cogeneration heat is insufficient due to insufficient power generation space,other methods are used to compensate the heating.Due to the change of operation mode of CHP plant,under the priority of renewable energy,what is the ability of cogeneration heating of CHP unit,how to tap the heating ability for CHP plant,does the CHP plant have enough heating ability to meet the requirements,a series of problems need to be studied.So,the work on these issues are summarized as follows:(1)This paper takes the extraction coal-fired CHP units as the research object,analyzes the influence of the "electricity-heat coupling" characteristic of the CHP unit on the absorption of renewable energy in the system,establishes the model of cogeneration heating capacity of CHP unit under the operation mode of " heat supply determined by the electricity demand ",analyzes the mechanism of low-pressure cylinder cut-off,electric boiler to improve the heating capacity of CHP unit,establishes the heating capacity model of CHP unit after flexibility transformation.(2)Taking the power balance of the power system side as the constraint and the maximum heating capacity of the heating system side as the goal,this paper establishes a model to calculate the heating capacity of electricity-heat integrated energy system.Based on the matching mechanism of heating capacity and heating load,this paper establishes the corresponding heating area model of the system,analyzes the mechanism of heat storage to enhance the heating area of the system and establishes the heating area model of the system after configuration of heat storage.(3)Based on the actual power supply structure,load forecast data and the heating ability model,this paper calculates the maximum heating power time series curve of the system.Based on the curve,this paper constructs the indicators representing the heating ability of the system,analyzing the influence of new energy forecast deviation,the minimum output of the pure condensing unit and penetration ratio of renewable energy on the heating capacity of the system.The analysis results show that large scale consumption of new energy will significantly reduce the cogeneration heating capacity of CHP plants.The low-pressure cylinder cut-off of the CHP unit can make full use of the waste heat of the low-pressure cylinder for cogeneration heating to improve the heating capacity of the unit,however,it can't solve the problem of insufficient cogeneration heating caused by the reduction of electric load.The essence of electric boiler heating is using the surplus capacity of the unit boiler for heating,the lower the electric load undertaken by CHP unit is,the larger its heating ability is,which can solve the problem of insufficient cogeneration heating supply caused by the renewable energy consumption on the power system side;In order to make full use of the heating capacity of CHP units,heat storage can be configured to stabilize the heating fluctuation and match the heat load to increase the heating area.By 2021,under the condition of priority consumption of renewable energy,the maximum heating area of the directly dispatched CHP units of the province will increase from 380 million square meters to 800 million square meters,which can reach 1.6 times of the planned target,and the total capacity of electric boiler required to be configured is 6230 MW,the total capacity of heat storage tank required to be configured is 67030 MWh,the maximum heat storage and release power is 10210 MW.Improving the prediction capacity of the renewable energy generation and reducing the minimum output rate of the pure condensing unit all can improve the heating capacity of the system in the heating period under various flexibility modification schemes.With the increase of the penetration ratio of renewable energy,the heating capacity of the system under the condition that the system is not reformed or only cut off the low pressure cylinder gradually decreases,while the heating capacity of the system after the electric boiler is configured increases with the increase of the penetration ratio of renewable energy.The proposed method and related conclusions can provide a reference for the system heating plan and flexibility transformation plan of CHP plants.