Anti-windup Strategies

3.6 Conclusions

In this chapter the integrator windup effect in the context of PID controllers has been analysed and different anti-windup techniques have been presented and compared.

Actually, all the considered methods are effective and each one has particular features that should be taken into account in a given application (indeed, there is not a technique that performs better than the others for all the kind of processes, PID parameters and actuator limits). From one point of view, the conditional integration approach has the advantage of being without an additional tuning parameter, but, from another point of view, the back-calculation methodology provides the capability to influence the transient response through the tuning of the tracking time constant (namely, a less aggressive response can be imposed by lowering the value of T_t). The combined approach seems to be less sensitive to the characteristics of the process. The two techniques considered for the PI(D) controller in automatic reset configuration do not show particular differences. With respect to them, a significant improvement in the performance does not actually emerges by applying the VSPID or the preload technique, despite they present a tuning parameter.