Application Research On Condensate Throttling For Primary Frequency Modulation Of Ultra-supercritical 1000 MW Unit

With the proportion of intermittent renewable energy generation such as wind power and solar energy and the disturbance factor of grid frequency increases,these requires coal-fired units with stronger controllability to participate in the deep primary frequency modulation of the grid.For steam turbine with full admission,high-pressure control valve throttle can quickly respond to grid load requirements,but resulted in large economic losses caused by deep primary frequency modulation requirements.In this paper,an engineering application of condensate throttling for primary frequency modulation control optimization based on super-supercritical 1000 MW steam turbine with full admission is studied.Research based on the existing control algorithm of primary frequency modulation,finds that the relative increment of power of primary frequency modulation increases with the running load of the unit declines,which causes large fluctuations in operating parameters,decreased operational stability and increased economic losses.The grid should improve the load rate of grid-connected units through optimizing load dispatch,to promote the energy efficiency of the whole society and reduce pollution emissions.Based on the Ebsilon software platform,the thermal performance calculation model of the ultra-supercritical 1000 MW steam turbine unit was developed.The generation output,the parameters of the turbine flow monitoring point and the heat consumption rate of different steam flow through overload valve and different rate of water by condensate throttling were carried out under different loads of the unit.The simulation calculation shows that the relative increment of the unit's generation output is proportional to the relative supplementary steam flow amount and the relative rate of condensed water by condensate throttling.The operation experiment of the overload valve function,the condensate throttling and the high-pressure control valve flow characteristic of the Jinling Power Plant NO.1 unit showed that the overload valve technology has a good primary frequency modulation performance,but The shaft vibration of NO.1 bearing exceeds the standard alarm at 30% opening degree;the condensate throttling also has a good primary frequency modulation performance,the deaerator and water level of the condenser are controllable,and the condensate water throttling adjustment reaches a stable value after 20 s.Based on the small opening degree of the overload valve with no vibration safety problem of the high pressure rotor and the initial corresponding speed of the condensate water throttle is slow,The primary frequency modulation compound method of the overload valve technology and the condensate throttling is proposed,the overload valve is quickly responded to the load requirement,the overload valve close slowly After condensate throttling is activated.The rapid response of the primary frequency modulation,the safety and economical operation of the unit are perfectly unified.Based on the operation experiment of condensate throttling and high-pressure control valve flow characteristics,the DEH valve management curve and the logic of condensate throttling for primary frequency modulation were designed on the DCS platform of Jinling Power Plant NO.1 unit,meanwhile,revised the logic for water level control of condenser and deaerator.This control method achieved optimizational control of frequency regulation,reduce the throttling loss of high-pressure control valve and improve the economics of unit operation.