The selections of nominal plant and weighting functions for robust control design

This paper presents the μ-synthesis robust control problem of the multi-model perturbed system of the leading and inertia sections of the superheater of a supercritical concurrent 600MW boiler. The strong change of the multi-model(including time constant, gain, even the orders etc.) of the controlled member occurs as the operating conditions are changed with extensiveness. A design method of μ-synthesis robust PID control system is proposed, the selections of nominal plant and weighting functions of the multi-model robust control system are discussed in the high, medium and low frequency change of the perturbed object. The μ -synthesis robust PI controllers are solved. Results of the design look as if they were normal PI controllers, but their control quality and robustness are better than the latter, and their structures are simple, definite, useful etc. The realization of the controllers doesn´t involve extra cost to the control equipment in existence. The results show that the proposed method is valid.