620 MW超临界机组辅机故障减负荷功能控制优化与应用

Optimization and Application of Run Back Function Control for 620 MW Super Critical Units

大容量、高参数火力发电机组良好的辅机故障减负荷(run back,RB)功能对电网的安全稳定运行具有十分重要的意义。为使RB过程更加安全可控、主要运行参数过度平稳,设计了RB控制策略,在两台新建机组上进行工程实践,并根据试验结果对RB过程中的给水、炉膛压力以及一次风压控制策略进行优化,旨在为同类型机组RB功能的正常实现、控制指标优良提供参考。采用所述的控制策略,实现了RB发生至复位全程零干预,并经过多次实践检验;通过针对性的优化避免了RB过程中过热度“虚高”引起的给水流量以及机组负荷波动,减弱了RB过程中各参数的相互副作用,较大幅度地提升了RB过程中炉膛压力控制的安全余裕,使其接近正常运行允许波动范围,进一步提高了RB过程的安全性和可靠性,对同类型机组具有参考价值。

Excellent run back(RB)function of the thermal power units with large capacity and high operating parameters is very important to the safe and stable operating of the electric grid.In order to enhance safety performance of the RB process and improve the control performance of the main operating parameters,RB control strategy was proposed and tested in two new units,and optimization methods for feed-water,furnace pressure and primary air pressure were proposed based on the analysis of test results.The purpose was to provide reference for the same type units to achieve normal RB function and excellent process control.By using the proposed strategy,the following results are got from the research.No operation is needed during the whole RB process,which is verified many times in factual application.After pertinent optimization,fluctuation of the unit load and feed water flow is avoided,which is resulted by fake high phenomenon of the superheat degree during RB process.Bad effect between operating parameters during feed water pump RB process is weaken.The safety margin of the furnace pressure control during the primary air fan RB process is highly enhanced,of which the fluctuation range is near to that of normal operation.The safety and reliability of the RB process is improved.