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发电锅炉燃烧过程Smith预估解耦控制策略

Smith Predictive Decoupling Control Strategy for Combustion Process of Power Boiler

  • 摘要: 针对燃煤发电锅炉多变量耦合、大滞后和非线性等特点,提出Smith预估解耦控制策略。以喷煤量和送风量为输入量、主蒸汽压力和排烟氧量为被控量,将燃煤发电锅炉控制系统中主蒸汽压力和排烟氧量两个相互耦合的调节回路解耦为两个互相独立的调节子系统;设计Smith预估补偿器对解耦后子系统中的滞后环节进行补偿校正。仿真结果表明:与前馈补偿综合法相比,系统运行1 000 s在主蒸汽压力回路加入干扰的情况下,主蒸汽压力调节时间减少208.33 s、超调量降低23.83%,排烟氧量调节时间减少90.91 s、超调量降低3.50%;在烟气含氧量回路加入干扰的情况下,主蒸汽压力调节时间减少166.66 s、超调量降低20.80%,排烟氧量调节时间减少166.66 s、超调量降低7.51%。工程应用表明,主蒸汽压力波动范围为设定值±0.3 MPa,排烟氧量波动值范围为设定值±0.5%,提出的控制策略具有良好的控制效果,能够满足燃煤锅炉控制的实际要求。

     

    Abstract: In view of the characteristics of coal-fired boiler, such as multivariable coupling, large lag and nonlinearity, a Smith predictive decoupling control strategy was proposed. Taking the coal injection rate and air supply rate as the input quantity, the main steam pressure and the oxygen content of exhaust gas as the controlled quantity, the two coupling regulating circuits of main steam pressure and oxygen content of exhaust gas in the control system of the coal-fired power generation boiler were decoupled into two independent regulating subsystems. A Smith predictor compensator was designed to compensate and correct the hysteresis in the decoupled subsystem. The simulation results show that compared with the feedforward compensation synthesis method, when the system is operated for 1 000 s and the main steam pressure loop is interfered, the main steam pressure regulating time is reduced by 208.33 s, the overshoot is reduced by 23.83%, the regulating time of exhaust oxygen is reduced by 90.91 s, and the overshoot is reduced by 3.50%. When interference is added in the flue gas oxygen loop, the regulating time of main steam pressure is reduced by 166.66 s, the overshooting amount is reduced by 20.80%, the regulating time of smoke oxygen content is reduced by 166.66 s, and the overshooting amount is reduced by 7.51%. The engineering application shows that the fluctuation range of main steam pressure is set value±0.3 MPa, and the fluctuation range of smoke oxygen discharge is set value±0.5%. Therefore, the proposed control strategy has good control effect and can meet the actual requirements of coal-fired boiler control.

     

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