| In recent years,with the rapid development of the wind power,the phenomenon of wind power curtailment can not be negligible,particularly in the “Three North” area of China,which is mainly owing to the insufficient flexibility of combined heat and power(CHP)units as a result of the heat-led mode of the CHP units.Therefore,more and more researchers have been paying attention to the utilisation of thermal inertia of the district heating system(DHS)to improve the operational flexibility of the CHP for wind power integration.However,for truly utilizing the thermal inertia of the DHS to integrate more wind power,several problems have still not been addressed by the relevant researchers,such as the dynamic thermal characteristic of the DHS and operation regulation of combined heat and power dispatch.The paper focuses on optimizing the operation regulation parameters and operation regulation mode of the combined heat and power system to utilize the thermal inertia of the DHS for wind power integration,and then improve the operation economics of the combined heat and power system.The hydraulic calculation model of the DHS was built and solved by loop method.On this basis,a hydraulic parameter identification method was proposed.In the method,firstly a resistance coefficient identification model of control valve was built to identify the resistance coefficient change of the control valve when the hydraulic condition was changed.Then,in combination with the adjustment characteristics of the valve,the opening of the valve was calculated.Meanwhile,the operating conditions of the circulation pumps was also optimized in the valve resistance coefficient identification.On the basis of hydraulic parameter identification,the dynamic thermal models of each component of the DHS were firstly built according to the conservation of mass and energy,in which the dynamic thermal model of pipe was built by the node method,taking into account the transmission time and heat loss of temperature in the pipe.Secondly,based on the graph theory and matrix theory,the ‘integration method' was proposed to dynamically connects the dynamic thermal model of each component of the DHS by the built connection pipe matrix,matrix of inlet node of connection pipe,connection pipe number matrix.And then the complete dynamic thermal model of the DHS was built.The actual operation data were obtained by testing a real heating system with large and quick temperature changes.Then the proposed DHS dynamic thermal model was validated by applying it to the real DHS and compared with measurements.The results showed that under the condition of large and quick temperature changes,the simulated average error of the supply temperatures and delay time at the fathest substation are 0.67? and 0.15 h respectively;meanwhile,the results also showed that the proposed DHS dynamic thermal model has the ability to simulate the dynamic return temperature at the heat source.Therefore,the accuracy of the proposed DHS dynamic thermal model was proved to meet actual engineering requirements.Moreover,The proposed model was also preliminary demonstrated that it can simulate the dynamic temperature distribution of complex DHS,which can featuring dynamic hydraulic condition and containing loops,multiheat sources.The principle of improving the operational flexibility of the CHP by utilizing the thermal inertia of the DHS for wind power integration were analyzed and the characteristc parameters of DHS thermal inertia were defined and calcualted.And then on the basis of hydraulic parameter identification and complete dynamic thermal model of the DHS,the combined heat and power dispatch models considering the thermal inertia of the DHS to integrated moer wind power were proposed for different operation regulation mode of DHS and solved by ‘MATALB+CPLEX'.The proposed combined heat and power dispatch models were applied to an combined heat and power system to quantitatively analyse the effects of the thermal inertia of the DHS on wind power integration and compare the effects of the operation regulation mode of DHS on wind power integration and the operation economic of the combined heat and power system on an typical day in Northeast China.The results show that the thermal inertia of the DHS can effectively reduce the wind power curtailment;the heat storage capacity of the used DHS heating for 10 millions m2 building areas in Northeast China can be equivalent to a heat storage with the volume of 20000m3 in the combined heat and power dispatch for wind power integration;by using the thermal inertia of the DHS,the abandonment rate of wind power can be reduced from 16.67% to 1.83% and the daily operation cost of the combined heat and power system can save 1.80 × 105? in a scenario where the average electric load is 500 MW,average predicted wind power is 100 MW,and the average outdoor environment average temperature is-10?.Furthermore,Based on multi-scenario analysis,the variable temperature-variable flow control was prove to be the optimal operation regulation mode to promote wind power integration and reduce system operating costs when utilizing the thermal inertia of the DHS for wind power integration in an combined heat and power system.Moreover,the the proposed complete dynamic thermal model of DHS was further demonstrated that it can simulate the dynamic temperature distribution of complex DHS,which can featuring dynamic hydraulic condition and containing loops,multi-heat sources. |
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