Abstract: A parametric model incorporating fan operating points, motor loads, VFD characteristics, and safety limits was developed for four auxiliaries in circulating fluidized bed semi-dry flue gas desulfurization. Conventional, proportional, and coordinated strategies were compared in 54 steady cases and three disturbances. Relative to conventional control, coordinated control saved 14.59% on average; proportional control violated 14 steady cases, whereas coordinated control was feasible throughout. Under compound disturbance, coordinated control used 2.08% more energy than the infeasible proportional strategy but eliminated 439 violation samples. Checking 48 low-confidence parameters against published gas-velocity ranges gave a tower area of 84.0 m2 and a minimum superficial velocity of 2.365 m/s; re-optimization retained feasibility without changing power. All 12 fan, motor, and VFD efficiency checks passed. Noisy DCS-like simulations identified 24 of 36 channels with a maximum mean time-constant error of 0.16%. The model supports power calculation, strategy comparison, feasible-region search, and dynamic safety-cost assessment; field use requires equipment curves and actual DCS data.