Research On Improvement Of Weighing Coal Feeding Control System

It is an important link in the production process to optimize the coal conveying and feeding system of thermal power plant by weighing coal feeding control system.In this thesis,firstly,the main equipment of coal handling control system and coal feeding control system is introduced in detail,and then the working process of coal conveying system and coal feeding system is described in detail.By summarizing the working principle of main auxiliary equipment,judging the fault phenomenon and introducing the protection measures,this thesis analyzes the current situation of coal conveying and coal feeding system in our plant,puts forward some equipment that needs to be improved and gives the upgrading design scheme of control system.In this thesis,the transformation design of roller screen of coal conveying control system,hardware upgrading design of coal feeder weighing system and PID control system of coal feeder based on speed feedforward are carried out.The core components of weighing and closed-loop PID regulation of the control system adopt the latest product of SDo C,i.e.decomont Tersus(dt-9)controller.The software and hardware of the coal feeder control system are upgraded,the weighing index after upgrading has been significantly improved,the frequency of system false alarm and refusing to move is obviously reduced,and the workload of maintenance unit is significantly reduced.#The upgrading scheme of control system for 6 coal feeders of 1 boiler is simple and easy to operate,which thoroughly solves a series of problems such as large measurement deviation,misoperation and refusing to move during operation of coal feeder,improves weighing measurement accuracy of coal feeder,improves operation safety and stability,has good benefits and effectively reduces maintenance cost of equipment.In this thesis,the scheme of using the speed signal of inverter output signal as the analog signal entering DCS system is designed.The feasibility of signal transmission is analyzed from the selection of inverter output signal,the transmission of analog signal,the conversion of signal mode,the display of signal and the verification of signal.The experiment is carried out during the shutdown of the unit,and the experimental results are good.The introduction of feedforward speed signal is the key part of the project design upgrade.How to introduce the local speed signal into DCS control cabinet determines the quality of PID controller in the later stage.In this project,the feed-forward compensation signal is introduced into the PID controller,which can effectively improve the poor regulation quality caused by the lag of feedback.Through a series of work,such as the construction of logical configuration,setting of adjustment parameters,recurrence of historical trend and comparison of performance indexes,it is proved that the introduction of feedforward compensation signal successfully improves the lag of the system,improves the regulation quality of the system,makes the reaction of the coal feeding system more sensitive and the coal feeding quantity more accurate,improves the combustion efficiency of the boiler and ensures the safety and stability of the unit Economic operation provides reliable guarantee.After running for more than half a year,the design scheme of this project is correct.The reconstruction of resonance probability screen makes the coal feeding weighing system more accurate;the upgrading of software and hardware of coal feeding system eliminates the potential hidden trouble and improves the measurement accuracy;the introduction of speed feed-forward signal basically eliminates the lag of regulator output signal caused by weighing feedback signal lag,and improves the control The system reliability and operation flexibility.