Study On Primary Frequency Modulation Optimization Method Of Thermal Power Unit

The premise of safe and stable operation of power grid is to ensure the stability of power grid frequency.Corresponding to the grid-connected power plant,frequency stability is ensured by controlling the rotating speed of steam turbine and generator output to achieve the function of primary frequency modulation.Therefore,the performance of primary frequency modulation directly affects the power grid frequency and power quality.In this paper,a 2×660mw ultra-supercritical coal-fired generating unit is taken as the research object.In view of the problems in the operation of the unit,such as high frequency swing,primary frequency modulation inverse modulation phenomenon and insufficient frequency modulation margin,combined with the primary frequency modulation performance test and the high frequency modulation flow characteristic test,an improved primary frequency modulation performance scheme is proposed from the following aspects.In the scheme,the linear variation of turbine valve is caused by the long service time of turbine valve.First,through flow characteristic optimization test of steam turbine valve,the actual flow characteristic curve of high profile steam turbine valve is obtained.After curve optimization,it is written into DEH system to improve the unit's primary frequency modulation performance.Then the traditional method that the turbine speed is no longer used as the given value is put forward,and the actual frequency of power grid is taken as the given value to complete the unit's primary frequency modulation.Finally,according to the actual operation of primary frequency modulation in power plant,the main problem is found in DEH side,the adjustment instruc.tion is transferred to the distributed control system,and the control logic parameters are adjusted reasonably,so as to improve the quality of primary frequency modulation control.According to the optimization plan in this paper,the unit's primary frequency modulation test was carried out again.The test data showed that the unit's primary frequency modulation function after optimization could fully meet the requirements of the primary frequency modulation assessment rules of northwest power grid,which achieved the purpose of our optimization and verified the feasibility and practicability of the optimization plan.