Identification of Three-Parameter Models from Step Response

Abstract

This paper provides an identification method for three-parameter models i.e. first order with dead time models and second order with dead time models. The proposed identification method is based on step response and can be easily implemented using digital microprocessors. The proposed method first identifies the order of the plant i.e. first order or second order from the behavior of the plant with constant input. After the order of the plant is determined, a test step input is applied to the system and the three parameters of the plant are obtained from the corresponding response of the plant. The output of the plant need not to be zero when the test signal is applied. The efficacy of proposed algorithms is verified through simulation and experiment.

Innovative Model-Based PID Control Design for Bus Voltage Regulation with STATCOM in Multi-Machine Power Systems

“…Furthermore, the resultant damping and oscillation coefficients for the dominant closed-loop poles are given by     and    , which are very close to the desired values (13). With these gains, the PID controller is implemented with a slight modification to the differential term:…”

“…In view of the constructed model, one can observe that there are two open-loop poles close to the imaginary axis and that these cause the oscillatory behavior of bus voltage response. On the basis of the observations of the model, a model-based PID control scheme is designed in such a way that the PID gains are determined in order to reduce the oscillatory behavior by moving the problematic poles to desirable places [13,14]. However, it is impossible to arbitrarily assign the closed-loop poles owing to the lack of degrees of freedom; i.e., the order of the closed loop system is higher than the number of PID controller gains.…”