基于凝结水节流串级控制的新型协调控制

摘要

新能源的规模化并网对火电机组变负荷能力提出了更高的要求,凝结水节流控制能够有效利用锅炉蓄热,达到快速变负荷的目的.本文设计的凝结水节流串级控制是结合凝结水节流控制的机炉协调控制系统,凝结水节流通道在调节初期利用机组蓄热快速响应负荷指令,并通过内回路保证除氧器水位不超限;机炉协调控制通道通过调节给煤量保证负荷调节后期的静态性能,包含凝结水流量控制和除氧器水位控制,这样保证了凝结水节流快速变负荷过程中除氧器水位的稳定.以某1 000 MW机组为例,对上述控制策略进行仿真,并应用IAE、ITAE和AGC考核指标对该新型凝结水节流串级控制策略与传统机炉协调控制策略进行量化对比,结果表明:凝结水节流串级控制大大提高机组升负荷速率,且负荷调节过程中除氧器水位变化较小.%Thermal power plants are required to improve the rate of regulating the power output for various renewable resources connect to the grid.Regulating the once through boiler load by condensate throttling can utilize the store energy effectively and enhance load response rate of the unit.The condensate throttling cascade control designed in this paper is a boiler-turbine coordinated control system combining with the condensate throttling.The condensate throttling channel can rapidly response the load instruction in initial stage of the regulation and the inner loop can keep the water level of deaerator varying in a safe range.Through regulating the feed coal quantity,the boilerturbine coordinated control channel ensures the static performance of the control system in last stage of the regulation,which includes the condensate flow control and water level control for the deaerator.Taking a 1000MW unit as the example,the above control strategy was applied to carry out the simulation.Moreover,the IAE,ITAE and AGC indexes were employed to compare the new control strategy with the conventional control strategies.The results show that,this condensate throttling cascade control dramatically enhanced the load rise rate of the unit,and the water level in the deaerator changed little during the whole load regulation process.