A rapid load varying control strategy for flexible operation of large scale coal-fired power unit under full operating conditions
With the increasingly prominent problem of load fluctuations in high proportion renewable energy grids,improving the fast load response ability of large-scaled thermal power units under full operating conditions has become an urgent need to maintain the safe and stable operation of the power system.Therefore,a rapid load change strategy combined with the high-pressure bypass transformation technology under the flexibility demand of supercritical power units is proposed.Firstly,the high-pressure bypass is added to the high-pressure regenerative system to flexibly change the steam extracted amount from turbine,thus to accelerate the energy supply rate of once-through boiler.Secondly,to adapt to the high ramping rate,a load change scheme is designed with the limitations of main steam pressure,temperature and their change rate that boiler can withstand at sliding-pressure operation mode and the decoupling of load-main steam pressure for unit.Finally,test on a 600 MW coal-fired thermal power unit shows that,the unit can successfully achieve a high load ramping rate of 3%Pe/min under full operating conditions.Moreover,the main steam pressure,position of main steam valve and other parameters are maintained stable.In addition,the load regulation ability of the unit with load ramping rate of 5%Pe/min is verified,confirming the effectiveness of the proposed load rapid regulation strategy.
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