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由于电网负荷指令变化频繁和煤质不稳定,火电机组更多处于变工况运行状态下,再热汽温控制品质难以满足要求。参考Smith预估器思想,利用被控制对象惰性区模型构造高阶导前微分环节,替换常规导前微分控制系统中的实际微分环节,构成高阶导前微分控制系统。系统达到最优的条件是,惰性区模型等于或接近实际对象,所以同时给出确定对象惰性区增益和惯性时间的方法。在此基础上,针对惰性区对象特性随机组负荷变化的问题,利用机组蒸汽流量信号在线调整模型参数,形成开环自适应系统以保证全负荷工况系统性能。工程实验证明,该方法具有控制品质好、物理意义明确、控制器参数整定简便的优点。
Due to the frequent change of grid load instruction and unstable coal, thermal power units are under more variable operating conditions and the quality of reheat steam temperature control is difficult to meet the requirements. With reference to the Smith predictor, the inertial zone model of the controlled object is used to construct the high-order derivative differential part to replace the actual derivative part in the conventional derivative control system to form the high-order derivative differential control system. The optimal condition for the system is that the inert region model is equal to or close to the actual object, so a method of determining the inert region gain and the inertia time of the object is also given. On the basis of this, aiming at the problem of load change of random group in inert zone, the model parameters are adjusted online by unit steam flow signal to form open loop adaptive system to ensure system performance under full load. Engineering experiments show that this method has the advantages of good control quality, clear physical meaning and easy tuning of controller parameters.