Decoupling Control Of Mill And Coal Pulverizing System And DCS Protectin Of Oil Station For Power Plant

Coal milling system is one of the most important system of the thermal power station, coal milling machine is the main equipment in coal milling system while it is the big electricity-consumed unit, its consumed electricity is a quarter of that used by all the whole power station. Now, in a majority of civil big or middle thermal power station, the operation of coal milling machine is still in the primitive status of human decision and hand operation, and the coal milling machine consumes the electricity largely, its economic benefit is poor. Therefore, it will bring good social and economic benefit if the operation status is improved and the computer control system for coal milling machine is developed.The operation of the coal milling machine takes on some remarkable characteristic such as the pure lag, big inertia and non-linear. Its dynamic characteristic is very complex, mathematic model is difficult to be build, and because of the variety of coal quality etc, the mathematic model varys slowly with the time. So adopting routine PID adjusting is very difficult actually to satisfy the need, even Smith pre-estimate control and Dahlin arithmetic are adoped, the exact mathematic model of controlled object should be known too, therefor it is not easy to obtain perfect control effect.The paper presents a kind of utility coupling-dispeled design way by combining Smith control and coupling-dispeled control. To HP863 coal milling machine, design and experimentation are performed, the engineering practice result indicated that the arithmetic was very simple and easy to realize by DCS, the designed system is capable to have good coupling-dispeled effect and resist disturbance, So the system is fit to spread in coal-combusting power station.After a complete tset of unit operate as a trial, every control system are launched one by one. According to the request of the standard in electric industry in China named "on line check and test rules of analog and digital control system of power station", every system is tested, and according to technological guides and operation rules, static and dynamic trial are required to be done, the quality of adjust, and response time also adapt to the requirement.The system has already operated for half a year, the practice proved that the design thought and design way are reasonable. It insured the functions of the system of the main machine OVATION are integrate, secure and reliable, reduced the labor intension of operation worker, offered abundant historic data and information which are neededby accident and trouble, and created the possibility of pre-controlling trouble, meanwhile, it provided effective an on line betimes monitor to lubricating oil system, decreased the economic loss as a result of the trouble of coal milling system in operation of the whole units.According to executing the technological reform to 300 MW units, the powerful control arithmetic and logical control function of OVATION were applied, FSSS system and protect function were more perfect, the quality of the operation parameter of the units was improved, the secure, effective and economic operation of the units was insured, and the automatization level of 300MW was promoted.