| With the proposal of the goals of the carbon peaking and carbon neutrality and the planning of the “14th Five-Year plan” power system,China has entered an important period of energy structure transformation,and clean energy generation represented by wind power and photovoltaic power generation has ushered in a key node of development,with a view to building a clean,efficient,low-carbon and environmentally friendly energy and power structure.In order to deal with the severe consumption problem caused by the rapid development of new energy power generation,thermal power units,as the main force of peak regulation,have to operate frequently in low load or variable load conditions,which has an adverse impact on the economy and safety of the units.At the same time,the price of thermal coal has soared and stayed at a high level in recent years,and power generation enterprises are facing greater challenges,so it is very important to calculate the online performance of thermal power units.On-line performance calculation can obtain the real-time performance index of the unit,clarify the energy saving potential of the unit,control and optimize the unit,and improve the overall efficiency of the unit.Therefore,focusing on the problem of on-line performance calculation of thermal power unit,this paper takes 660 MW ultra-supercritical unit as the research object and carries out the following work:(1)The thermal system calculation of the unit was carried out.First of all,the thermal system structure of the unit studied in this paper was analyzed,and the thermal economic index calculation models of boiler side,turbine side and the whole plant were established.Then,taking the THA working condition of the unit as an example,the method and steps of thermal system calculation of steam turbine unit were given in detail,and the MATLAB/Simulink simulation model and DCS algorithm configuration were established.Finally,based on Hollysys DCS system,the on-line performance calculation function was realized on the #5 and #6 units of power plant;(2)The influence of steam turbine heat recovery equipment on the thermal economy of the unit was calculated and analyzed.By using the equivalent enthalpy drop method,the influence of heater terminal temperature difference of the regenerative system on the thermal economy of the unit under variable working conditions was calculated and analyzed.The results showed that the terminal temperature difference of the highest level of high pressure heater has the greatest impact on thermal economy.According to the calculation method of thermal system,a calculation model of unit under variable working conditions was established,and the influence of external steam cooler on the thermal economy of the unit under variable working conditions was calculated and analyzed.The results showed that the average heat rate of steam turbine was reduced by about19.4k J/k W·h,and the average coal consumption of standard power supply was reduced by about 0.75g/k W·h;(3)The main operating parameters of the unit were analyzed.Firstly,the determination method of the reference value of the main operating parameters of the unit and the detailed steps of the calculation method of the steam turbine unit under variable working conditions were introduced.Then,the variable working condition calculation model of the unit was established,and the influence of six main operating parameters on the thermal economy of the unit were calculated and analyzed,including main steam temperature,main steam pressure and reheat steam temperature.Finally,the DCS algorithm configuration was set up,and the function of energy-loss analysis was realized on the #5 and #6 units of power plant,and the operation result was good. |
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