Research On Key Technologies And Application For Coal-fired Power Unit Based On "Two Rules" Assessment

"The detailed implementation rules for the auxiliary service management of the power plant in north China" and "the detailed implementation rules for the operation and management of power plants in north China" were issued by the North China Electric Supervision Bureau(hereinafter referred to as the ’two rules’)in November,2008,which put forward higher requirements for the integrated control of the thermal power generating unit.However,as for the present large-scale automatic generation control(AGC)unit for thermal power,its actual running performance is different from its test performance due to coal property change,different running modes,actuator change,thermodynamic system and other factors.What’s more,desulfurization system,denitrification system and other additional factors are also exerting a profound impact on the original frequency and peakload modulation capacity of the unit.Therefore,it is very necessary and has the application prospect and significance to carry out the automatic control application research and comprehensively improve the frequency control performance under the AGC running mode of large-scale thermal power generating unit.Focusing on the characteristics of the load control and primary frequency control of the power unit under the power grid interconnection and the power grid assessment management standard,the common control problems of the thermal power unit under the automatic generation control mode were summarized,the standard requirements of the power grid dispatching for the load control and the response characteristics of the power unit were analyzed,and a method of adjusting load dynamically under the AGC mode was proposed,which can effectively guarantee the regulation rate,regulation precision and the response time index under the PROPR mode of the power unit.In addition,primary frequency control technology based on automatic valve operation was also proposed,which effectively solved the difference of action index caused by the difference between the single valve control mode and the sequence valve control mode.The primary frequency control optimization method and system based on the overshoot compensation was put forward,which effectively improved the problem of slow frequency modulation response caused by the inherent delay of the equipment itself and increased the pass rate of the primary frequency modulation action.The research on the intelligent control device of primary frequency modulation was done,and the primary frequency modulation optimization control device based on the dynamic compensation for the power measurement error was developed to realize the homologous unification of the frequency modulation signal.The times of the primary frequency modulation maloperation for the power unit were reduced greatly without movement resistance.Therefore,the primary frequency modulation action range decreases by no less than 30%,the pass rate of the primary frequency modulation reaches no less than 80%,the action times decrease by no less than 20%,the AGC index maintains above 2.3 and the main steam pressure fluctuation is within 0.4MPa.The homologous transformation of primary frequency modulation has significantly reduced the maloperation times and the action range of the power unit,and the impact of the frequency modulation on the control valve of the unit has been reduced.It is very important to prevent the incident of the broken shaft of the control valve.This technology has be applied to the 300MW unit of Tengzhou Xinyuan thermal power first.It is proved through long-term running that the primary frequency modulation homologous optimization control system is safe,reliable and steady,which can meet the primary frequency modulation performance index under the power grid assessment and guarantee the good performance index of the AGC and stable running of power unit.At present,this technology has been applied to 69 units from the 101 units listed to the primary frequency modulation assessment management of 300MW level or above of Shandong Power Grid.The market prospect of this technology is bright.