PLC uses AB's PLC-5/20 processor. For the convenience of maintenance, it is divided into three independent stations according to the professional nature: thermal measurement and control station, monitoring and protection station and electrical control station. The thermal measurement and control station is responsible for the detection of all thermal parameters of the unit and the water level control of the steam reheater, high pressure heater and low pressure heater. The monitoring and protection station is responsible for the protection control and monitoring alarms for the operation of the unit. It is dual-CPU hot standby and connected to the public remote I/O rack through a remote link. The electrical control station is responsible for the control of the electrical equipment of the unit and the start and stop operation of the unit. The two machines have the same application in important parts and can be used alternately to improve the reliability of the system application. The controller adopts the PROTRONICPS small digital control system manufactured by HARTMAN-BRAON, a total of four, plus a countercurrent protection logic unit for controlling air volume, wind pressure, steam pressure limit and anti-surge. The output of the air volume and steam pressure controller is connected to the wind pressure controller, and after the comprehensive calculation processing by the wind pressure controller, coordinated control is performed. The controller is connected to the PLC via an I/O channel to form a complete control system.
Air volume, wind pressure, and steam pressure control air volume control are used to adjust and set the air supply value of the unit and keep the air volume constant. Wind pressure control is used to limit the wind pressure to within limits. Steam pressure control prevents rotational stall failures when the steam pressure drops and limits the engine room pressure below the limit. All three adopt PI control mode, and adopt optimization measures such as asymmetric output control and automatic ramp-up method of loading and unloading. The adjustment targets of the three controllers are the same. For the coordinated action, the output values â€‹â€‹of the air volume and the steam pressure controller are added to the PI control block of the wind pressure control, and the minimum value is selected as the common output value. The output needs to adjust the turbine speed and the fan stator blade angle separately. The two must be closely matched. Therefore, a separate operation block is added, and the actual control values â€‹â€‹of the two are calculated according to the derived mathematics. In order to monitor and operate the normal operation of the unit, the monitoring system uses two industrial computer as the upper computer. Using the RSView software and V.Basic language of Rockwell Automation, a complete blower monitoring system is established, and the following functions are completed to collect all the data in real time. Establish a real-time database and use different scanning cycles to establish historical databases for days, weeks, months, and years. Provides dynamic condition operation diagram, system flow chart, control parameter setting diagram, various parameter tables and trend curves. In order to adapt to the on-site operating environment, the call display of all the screens is controlled by the buttons on the panel, and the supervisory driver is programmed for each button. Each screen sets various soft keys, writes corresponding macro commands, and selects different screens by controlling the focus movement in the event trigger form. (In the form of Recip), the parameter value can be set and modified for the lower computer control loop at any time. The alarm record file is created for the main status parameter and stored in DbaseIV format. At the same time, the alarm status bar window is established to display the latest alarm information in real time.
PLC internal fault handling subroutine PLC internal fault handling subroutine is used to monitor the faults caused by PLC software and hardware, take corresponding measures, and deal with them in time to reduce the fault hazard. The subroutine mainly monitors the error code and status code generated during PLC operation, and takes corresponding data protection for different operating states of the PLC. Corrective handling and prompting for recoverable errors; appropriate shutdown processing and alarms for unrecoverable faults. The fault subroutine is stored in the location specified by PLC-5 and is automatically called when an abnormal state or error code occurs.
Conclusion Since the control system was put into use in April 2000, the system has been stable and reliable, with precise control, sensitive to emergencies, easy operation and maintenance, clear indication of the working status of the unit, improved operating conditions and greatly improved blower. Operational efficiency and safety level.
Resistance type Strain Gauge is sensitive component, which uses resistance-strain effect and converts strain quantity of test piece into resistance change quantity, is the widest strain test component at present, and is mainly used in weighing/force measuring field.
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