Research On Fuel-steam Pressure Fractional-order Modeling And Control For Supercritical Once-though Boiler

The steam water flow of supercritical boiler is completed with once through. Therefrigerant flow and energy flow couple together. There is serious coupling betweenturbine and boiler. one of the important symbols which can measure the energy balancebetween turbine and boiler is the main steam pressure. It is one of the important processcontrol parameters of supercritical units at the same time. The fuel—pressure controlsystem of the supercritical once through boiler has some characteristics including largedelay, large inertia, strong coupling, time-varying parameter. So this paper studies thefractional order control which is an advanced control theory. Introduce it tofuel—pressure control system of the supercritical once through boiler. Since thefractional calculus of the order can be arbitrary, it expands the integer-order calculusdescription ability, therefore Fractional model can more accurately describe the dynamicresponse of the actual system. Compared with the integer order PID controller, fractionalorder PID controller more than two adjustable parameters, extends the integer order PIDcontroller tuning range, it can be more flexible control of the controlled object, toimprove quality control.Analyzed1000MW unit Supercritical static characteristics, and calculate the amountof fuel and feed water disturbance on the boiler outlet steam pressure and steamtemperature. The results show that the amount of disturbance to the water vapor pressureof the boiler outlet disturbances affects smaller than fuel; both of them have littledifference on main steam temperature and the opposite direction. In order to overcomethe disturbance of fuel impact on vapor pressure system proposed coal power factorconcept. Coal power factor to reflect the changes of coal quality in real time, thesystem has the ability to automatically adapt to changes in coal quality. Through theanalysis of influence factors of main steam pressure and the operationcharacteristics of boiler, this paper makes a fractional order model and integer ordermodel identification with the Particle Swarm Optimization algorithm for a1000MWunit. The identification results show that the fractional order model is more accuratethan the integer order model. Design a fractional order PID controller with theParticle Swarm Optimization algorithm and compare with the traditional PIDcontroller. Simulate in MATLAB environment, the results showed that the fractionalorder PID controller has the strong robustness and anti-interference ability.