火电机组协调系统的非线性串级控制研究

Nonlinear cascade control research of a drum boiler turbine unit in thermal power plants

为了克服大型火电机组汽包型锅炉生产过程中存在的非线性强和指令响应慢的缺点,构造了一种非线性串级控制结构:外控制环以主汽压力为控制对象,将其控制器输出作为汽包压力设定值;内控制环则依据汽包压力与其设定值的偏差的大小调节锅炉的供给燃料量.仿真表明:与PI控制相比,在本设计系统的控制下,主汽压力的动态响应速度更快、超调量更小;当主汽压力受到0.1MW外扰作用及模型失配20%的情况时,非线性串级控制系统仍具有良好的大范围升、降负荷指令跟踪性能和稳定性.

To deal with the severe nonlinearity and slow dynamic responses of a large drum type boiler in thermal generate power units,a nonlinear cascade control structure was developed.The object of outside control loop was throttle pressure.The output of master controller was considered as the set point of drum pressure.In the inside control loop,the difference of drum pressure and its set point was used to regulate the fuel feed flow ratio.Simulation results show that comparison with the PI（proportional plus intergral plus） control method,the designed nonlinear cascade control system can gain a shorter transient time and smaller overshoot in the throttle pressure dynamic process.The designed control system can still exhibit a good tracking performance and stability while the operation is over a wide range,with 0.1 MW external disturbances on the throttle pressure and 20% model mismatch.