Influence Of Different Extraction Conditions On Frequency Regulation Capability Of Heating Units

With the development of electric power industry in China,the total installed capacity of heating units in China is larger and larger.These units are involved in heating in winter so that the dynamic characteristics of primary frequency regulation vary with the heat input of steam turbines and the performance of primary frequency modulation decreases with the increase of extraction steam.In order to study the response characteristics of the unit to the frequency under the condition of large extraction steam,this paper has done related research.Based on the research status of primary frequency regulation capability analysis of heating unit,the primary frequency regulation principle and control processes are introduced.And on the basis of the primary frequency regulation principle and the Simulink software platform,the prime mover model and control model of the heating unit with primary frequency regulation capability are established.The power output characteristics of steam turbines are analyzed by simulating.A primary frequency regulation test was carried out for typical generating units and the performance parameters of units under different extraction conditions were recorded.According to the test results,the power correction coefficient of the low pressure cylinder is added to the model,time constant of the connector of medium cylinder and low pressure cylinder is corrected for the heating unit,and multiplier is added to correct the influence of main steam pressure at the same time.It is proved by the test that the correction of the power output of the low pressure cylinder and time constant of the connector of medium cylinder and low pressure cylinder in the model has achieved the effect.It is concluded that the main reason for the decrease of primary frequency regulation is that the power output of the low pressure cylinder is insufficient and the load response speed decreases.The response characteristics to the speed difference disturbance of the unit under different extraction conditions and different main steam pressures are studied by running the modified simulation model.The concept of frequency modulation allowance is defined and comparing the simulation results,it is concluded that the increase of the steam extraction volume and the decrease of main steam pressure both will lead to the decrease of frequency modulation allowance.The above shows that the model can reflect the main dynamic characteristics of the unit and provide a more practical reference for the stable operation of power network and simulation calculation.