Closed circuit television system for Sagardighi (2×300MW) power plant is designed with full digital plan. The project is for 2×300MW subcritical burning-coal steam turbine power unit. The closed circuit television system is installed to monitor and control #1 unit area, #2 unit area and common system area. The system is composed of the following units: front camera unit, transmission unit, network unit, as well as the unit for system center management, control, video record and display.
Closed circuit television system is composed of four units: 55 cameras, network transmission unit, control unit, display and record unit. Each unit includes more concrete equipments or parts. System structure schematics is as following:
Video Streamers COLOR DOME Control Center ` deco der Video Streamers Switch Color CCD Camera Video Manager
NetWork Record Server
CLIENT 2
To 2# lvs
CLIENT 1
To 1# lvs
1#Unit 2#Unit Common System
All functions are designed with modular. User can modify and expand its functions according to actual demand. The system can set up different user levels, provide simple and practical man-machine interface with graphic window, which is extremely convenient for system administrator's operation. At the same time, using customer - service network topology structure, the system administrator can easily add or subtract the actual number of motoring places, and can conveniently change the definite position of central monitoring workstation, which enhances the system utilize efficiency, and enable the whole closed circuit television system serve the power plant with high effect and great flexibility.
Camera
Camera part is the front part of the TV monitoring system and “eyes “of the whole system. Its function is as follows:
Camera is selected to suit to the indoor environments and agree with industry standard.
The selected cameras have backlight compensation function according to the size and contrast ratio of the subject in the whole image, the compensation electrical level needed is calculated automatically. Even at some positions of
monitoring point the backlight phenomenon is difficult to be avoided, the compensation function of a poor light of camera
can enable the system to produce the satisfied image, too. When the camera is shot by strong light, the camera can not be damaged or focus light, and the image is neither lost.
By selecting the camera with the low intensity of illumination, and the super strongly dynamic CCD can also take relatively clear pictures in the area of faint light source. The built-in synchronizer of the camera can select the synchronous way or outer synchronous way according to the conditions, and under any circumstance the image scroll won’t take place in order to keep the video signal vertical and in same phase.
Specification of System Equipments
The camera of this system design selects 11 integrative and intelligent high-speed dome type cameras (ENVD2450M is Day/Night, Color &B/W versions) and 44 color CCD cameras (LTC0455/51 is Day/Night, Color &B/W versions) of BOSCH, which guarantees high performance, high sensitivity effect and high quality pictures. The cameras with Pan/Tilt and zoom lens were selected to achieve a broad field-of-view angle and basically have no dead angle in main workshop area and other system areas. Thus we can monitor a long distance object, and save the number of cameras. Under a bad environment for monitoring, the outdoor camera housing (PT5723-3) with sun shroud, thermostatic fan & heater and wiper functions was used against adverse circumstance.
There are three cables for dome type camera (ENVD2450M), which includes power cable (AC24V), video cable (SYV 75-3) and RS485 control cable. An outdoor dome can be assembled for the dome type camera, which can be installed in wall-installation way
or in hanging installation way with corresponding support. The video signal of camera and the RS485 control signal of decoder are directly sent to the video Streamer (VIP X1). The camera power source AC240V of unit control room is transported to monitoring spots, then is transformed to AC24V as power source of equipments.
The color CCD camera (LTC0455/50) with electric zoom lens (LTC 3384/21) is installed in outdoor camera housing or indoor full function camera housing. The camera housing is installed on electric Pan/Tilt (LTC9420/11). The decoder (LTC8566/50) provides power source for camera, lens control and Pan/Tilt control. The camera video signal and RS485 control signal of decoder are directly sent to the video Streamer (VIP X1). The camera power source AC240V of unit control room is transported to decoder which will provide power source for front equipments.
RUNBACK ( RB )
Runback function principle.
RB is the short form of Runback which means the main auxiliary fault-trip due to unit’s actual power limitation. Control system still force to decrease the unit target load rate. This function called auxiliary unit fault load reduction. The perfect RB control strategy is established on the basis of coordinated control system. Every system must be internally coordinated (coordinated control system) and such ensure the balanced transition of the operation condition. The external coordinated control system such as FSSS, SCS, DEH, works very fast to stable the load to be decreased to unit output for premises of scope.
The condition to Runback-
I. Unit is on coordinate mode. II. Power load < 180 MW.
III. Runback push button is put into service. Runback items running condition.
The unit designs have 6 kinds of items:
a) Load < 180 MW, two ID fans in operation, and one ID fan trip. b) Load < 180 MW, two FD fans in operation, and one FD fan trip. c) Load < 180 MW, two PA fans in operation, and one PA fan trip. d) Load < 270 MW, 4 Mills in operation, and 1 mill trip.
e) Load < 220 MW, 3 Mills in operation, and 1 mill trip.
f) Load < 180 MW, 2 Feed water pump in operation, 1 Feed water pump trip.
When these conditions are fully qualified and any auxiliary trips then Runback happen. i. The process after the Runback happened.
The unit is in coordinate mode & operation is in constant pressure mode, boiler adjusts power, turbine adjust main steam pressure. According to normal working condition the target load of boiler [ 4 mill for 230MW, 3 mill for 180MW, feed water pump RB for 150MW, PA fan RB for 160MW, FD/ID fan RB for 180MW] corresponding coal feeding flow works as reducing fastly the load order of the boiler load. And according to the turbine pressure the governing pressure valve is to be set up.
ii. After RB happened automatically shut down all the super heater and reheater attemperating water, motor valve & governing valve (4 mills except RB).
iii. After RB happen when 2 mills are running in every 10 seconds 1 mill automatically trip. Trip mill sequence will be F,E,D,A,B,C. if the B or C flow mill is running then BC flow light-heavy oil gun automatically put into service.
iv. When load reduced to target value then automatically reset RB. Or after the load getting stable – manually reset mode is closed. At this time the unit coordinate control & stable pressure mode , turbine adjust unit power mode .