Measurement noise and disturbance rejection for unstable SOPDT process

In this paper, a novel control structure method is proposed to obtain superior output response of the process in the presence of measurement noise and load disturbance. The derivative controller in the inner loop is aimed to stabilize the unstable SOPDT process and also reduce the effect of derivative kick and noise. Four parameters PID with series lead-lag filter are designed based on IMC principle for disturbance estimator. To achieve better output response, even in the presence of measurement noise, a first order low pass filter is inserted in the loop to denoise the output signal.