Research On Accommodating Wind Power By CHP Based On Heat Accumulator

At present, during the heating season in the northern China,"wind heat conflict" leads to abundant curtailments of wind power more and more seriously, which has become an issue of concern of the whole society. The reason of conflict is that cogeneration unit has to improve its minimum output for meeting the heat load, which causes the lack of space for wind power integration. Thereby, a scheme is proposed that decreases the minimum output of CHP in our country by installing heat accumulator in the period of curtailed wind in this paper, which accommodates wind power. The mainly works and results are presented as follows:Firstly, the peak-load regulation ability of cogeneration unit with heat accumulator is analyzed to verify the technical feasibility of the scheme. The external characteristics of extraction cogenerating units with heat accumulators are modeled, and the operation mechanism is discussed. On this basis, the corresponding mathematical model for calculating the peak-load regulation capacity of cogeneration units with heat accumulator is established. The example analyses the effects on improving peak-load regulating ability of300MW and200MW typical cogeneration units in the north of china by adding heat accumulators, the results show that:under the level of heat load in current heating middle period, the peak-load regulating capacity of300MW and200MW units can increase by21%and13%of their nominal capacity by adding heat accumulators respectively, providing massive room for curtailed wind power.Secondly, a comprehensive combined power and heat dispatch model including heat accumulator is built to adapt the centralized dispatching operational background of current power system in China. Compared with traditional model, the new model has additional restraints:the system heat balance, the thermoelectric coupling of CHP unit and the operation of heat accumulator, and takes the minimum total coal consumption for both electricity and heat as its objective. The example verifies the effectiveness of the model, and shows that CHP plant with heat accumulator can effectively improve grid wind power accommodation level, and the coal saves per1MWh wind power benefit accommodation by heat accumulator is better than that by electric boiler.Lastly, a dispatch model based on scenario analysis including heat accumulator is built to make the next day operation strategy of heat accumulator, which considers uncertainty of wind, the model describes uncertainty of wind by scenario analysis method, and the objective function is the expectation of coal consumption under various scenarios. In view of the complexity of model, proposing a practical method to decrease calculation amount, through using different wind power scenarios integrated into comprehensive combined power and heat dispatch model to make alternative operation strategies, then establishing an index of "coal saving" expected value to evaluate, finally choosing the strategy corresponding to maximum "coal saving" expected value as the next day operation strategy of heat accumulator. The example verifies the effectiveness of the above methods, and shows that, the results obtained from practical method is basically similar to scenario analysis dispatch model.The research of this paper shows that the CHP plant installed heat accumulator is an effective means of promoting development of wind power and cogeneration power coordinately and friendly, which can effectively relieve the current "wind heat conflict" and provide a feasible solution to solve the abandoned wind problem in China.