PI controller gains tuning of the pressure control system by open-loop frequency response (thermal power plants)

A description is given of the tuning method for the boiler air draft control system of coal-fired thermal power plants, especially the speed control of the forced draft fan which supplies air to the boiler. The system transfer function is modeled as first-order system with time delay. The proportional-integral (PI) gains are determined by the Ziegler-Nichols tuning method based on open-loop frequency diagram which is developed from the pulse test data under the various operating conditions. Tuning the gains with this method resulted in successful results, and the validity of design procedure is confirmed through simulations and experiment.<
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