Research On Control System Of Reheat Steam Temperature And Dynamic Characteristic Analysis About A Double-reheat Ultra-supercritical Units

As the state of energy utilization and environmental protection increasingly strict,with the smooth implementation of the "big pressure on the small" policy,in the foreseeable future,boiler inevitably towards large capacity,large unit development trend.Ultra supercritical two reheat unit has excellent environmental effect and good economic benefits,and China has a solid material technology and thermal control technology,so the development of ultra supercritical two reheat unit will be China's development of high parameter and large capacity unit choice method.But because the two time complexity of reheat unit structure and particularity,so two reheat unit is big lag and large inertia is very obvious,so how to timely and effectively to reheat steam temperature control becomes a stumbling block to the development of the two reheat unit.This paper first analyzes the domestic and foreign existing two reheat steam temperature control strategy,according to the mass conservation and energy conservation equation,method of linear distributed parameter modeling,and using the low order approximation method and combined with the physical concept of a reasonable mathematical model is simplified to get two reheat unit.On this basis,a set of reheated steam temperature control scheme is obtained by combining PID control with state feedback.Finally,the simulation experiment of the control scheme is carried out on the platform of Matlab/Simulink.In this paper,the flue gas damper and the burner swing angle coordinated action are adopted to control the reheated steam temperature by taking the water jet temperature reduction as the control plan of the accident water injection.At the same time,in order to eliminate the large inertia and large delay of ultra supercritical two reheat unit,a control scheme combining PID control with state feedback control is proposed.Easy,timely and accurate estimation of the change of steam temperature.Burner angle adjustment,with one or two temperature of reheat steam automobile adjust the value and the actual value between the large deviation;regulating gas baffle,so that the deviation between the zero as the target of regulation.Adjustment of burner swing angle and regulation of flue baffle at the same time.The design of the control scheme through Matlab simulation test platform,it proves that this scheme can effectively eliminate two reheat ultra large inertia and large delay of supercritical unit,has good control performance and fast response speed.Through the demonstration and analysis of this paper,it can be used for reference to the new super supercritical two reheat unit in china.Easy to be mastered by engineering personnel,so as to facilitate popularization.