中文摘要：

在连续生产过程中,工艺上通过设立缓冲容器来解决前后工序之间的物料量突变,以确保生产的平稳性,针对这类容器的液位控制,常规PID定值控制已满足不了上述要求。为解决这个问题,以长期现场实践为基础,根据操作人员的思维特性,提出了一种基于模糊控制和常规控制相结合的液位区域控制方法。该方法以液位的上下限和变化量作为输入模糊量化依据,改变了传统输入模糊量化方法,同时对于模糊输出量到控制输出采用新的转换方法,使模糊输出离散量转化为希望调节的液位量。为提高控制精确度,在实际控制输出与希望调节偏差较大时,增加了输出校正环节以减少输出误差。这种方法允许液位在给定的高低限范围内波动,以保证送出的物料缓慢平稳变化;只有液位超出高低限时,或液位在正常范围内,并且液位变化量超过给定阈值时才进行调节,以确保维持下游工序的负荷平稳。实际应用结果验证了这种方法的有效性。

英文摘要：

Considering the stability of production and the balance of load the process requires that the materiel quantity should change slowly or be kept unchanged. It can be solved by controlling the liquid level of buffer container. However, the classical PID method cannot control the level of the horizontal container and the processes with phase change and disturbances. Based on practical experience a zone control method combined with fuzzy control and classical control was proposed. This method took the high limit, low limit and changing value as the basis of the input fuzzy values. It changed the classical fuzzy methods and used a new strategy to transform the fuzzy outputs and the control outputs which transformed the fuzzy outputs to the expected level values. A tuning output term was added to enhance the control accuracy when considering large deviation between practical outputs and expected outputs. This control method allowed the liquid level to fluctuate within the set range, and guaranteed a slow and stable change of materiel quantity. When the liquid level went beyond the set fluctuation range or the variable liquid level exceeded the set point, it was adjusted to ensure the stable load of the downstream unit. A practical application proved the effectiveness of the zone control method.