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分析了PID控制算法与热工被控对象数学模型的关系,指出误差及导数结果中包含关于热工对象的丰富信息,加强对这些信息的分析可以提高PID控制器的性能。闭环系统在阶跃扰动下的动态过程可分为两个阶段:第一个阶段是处于远离热力学平衡态的非平衡定态。在较长的时间内围绕其某个固有频率维持高阶振荡。第二个阶段是闭环系统进入了线性非平衡热力学范围,PID调节器退化为积分调节器。以系统自由能耗散率为参数,提出了基于智能积分的PID控制算法,能动态改变比例增益和积分作用,有效地提高系统快速性和稳定性。通过某锅炉主汽温对象的仿真实验表明,其性能优于常规PID控制器。
The relationship between the PID control algorithm and the mathematic model of thermal controlled object is analyzed. It is pointed out that the error and derivative results contain rich information about the thermal object, and strengthening the analysis of these information can improve the performance of the PID controller. The dynamic process of a closed-loop system under step disturbance can be divided into two stages: The first stage is an unbalanced stationary state far from the thermodynamic equilibrium state. In a longer period of time around a certain natural frequency to maintain high-order oscillation. The second stage is the closed-loop system into the linear non-equilibrium thermodynamic range, PID regulators degenerated into integral regulator. Taking the dissipation rate of free energy of the system as a parameter, a PID control algorithm based on intelligent integral is proposed, which can dynamically change the proportional gain and integral function and effectively improve the system’s speediness and stability. Through a boiler main steam temperature object simulation experiments show that its performance is superior to the conventional PID controller.