Composition and configuration of GPS Beidou clock synchronization (satellite time synchronization system) in power plant

Power plant GPS Beidou clock synchronization （ Satellite time synchronization system ） Composition and configuration
Power plant GPS Beidou clock synchronization （ Satellite time synchronization system ） Composition and configuration
With the rapid development of computer and network communication technology , Digitization of thermal automation system in thermal power plant 、 The era of networking has come . On the one hand, it is the data exchange between control and information systems 、 Analysis and application provide a better platform , On the other hand, it puts forward higher requirements for the accuracy of time tags of various real-time and historical data .
Use the inexpensive satellite clock to unify the clocks of various systems in the whole plant , It has been the standard practice adopted in the design of thermal power plants at present .
Unit distributed control system in power plant 、 Auxiliary system programmable controller 、 Plant level monitoring information system 、 Power plant management information system （MIS） Wait for the master clock to pass the appropriate GPS Beidou clock signal interface , Get standard TOD Time , Then according to their own clock synchronization mechanism , Limit the clock deviation in the system to a small enough range , So as to achieve the clock synchronization of the whole plant .
One 、 Composition of clock system
The clock synchronization system has many composition modes , There are two typical forms , They are as follows ：
1、 Single master clock synchronization system
By a master clock 、 Multiple slave clocks and signal transmission media , Used to set the time of a given device or system , According to the actual needs and technical requirements , The master clock can reserve an interface to receive the wired time reference signal sent by the upper level clock synchronization system .

2、 Dual master clock synchronization system
It consists of two master clocks 、 Multiple slave clocks and signal transmission media , Used to set the time of a given device or system . According to the actual needs and technical requirements , The master clock can reserve an interface to receive the wired time reference signal sent by the upper level time synchronization system .

Two 、 Configuration of clock synchronization system
1、 Single master clock synchronization system
Beidou +GPS, Suitable for small power plants 、35kV And the following substations .
2、 Dual master clock synchronization system
Double Beidou + double GPS, Applicable to control centers at all levels 、 Large power plants 、110kV And above substations .
3、 ... and 、 The basic composition of clock synchronization system
The clock synchronization device is mainly composed of 3 Most of the components ： Clock input unit 、 Internal clock unit and time output unit .

Technical specifications of clock input unit ：
GPS frequency ：1575.42MHz（L1 The signal ）
Reception sensitivity ： <-165 dBW
At the same time track ： As much as 12 A satellite
When the unit is cold started , No less than 3 satellite
Capture time ： Recapture <2S
When the unit is hot started <15S
When the unit is cold started <35 S
1PPS precision ： be better than 200ns( The absolute value )
Beidou receives the signal
frequency : 2491.75±4.08MHz( Spectral zero bandwidth )
Received signal power : C=-157.6dBW( Antenna port surface I Branch signal power )
Elevation : 10゜～75゜
Receive carrier frequency offset : ≤±500Hz (C=-157.6dBW)
Receive PN code frequency offset : ≤±0.2Hz (C=-157.6dBW)
Internal clock unit index ：
Built in constant temperature crystal oscillator , When not tracking satellites , The leading edge deviation of output pulse shall not be greater than 0.6μs/min.（ Optional rubidium clock, etc ）
Time output unit index ：
1）1PPS and 1PPM Pulse signal （TTL level ） Output , As a test port
2） Definable 1PPS、1PPM Pulse signal （ Air contact ） or 24V Active pulse output
2） Definable 1PPS、1PPM Pulse signal （ Differential signal , namely RS-422 level ）
3） Time date message serial port （RS－232 or RS-422） Output
4）IRIG-B（DC RS－422） Time code output
5）IRIG-B（DC TTL） Time code output
6）IRIG-B(AC) Time code output
7）DCF77（ Blank nodes ） Time code output
8） Frequency measurement data output
9） Network output （PTP/NTP）
The outputs are isolated from each other , The number of various synchronization signals can be combined according to actual needs , Each signal output interface can only be connected to one time service equipment . When there is no requirement for common land ,IRIG-B（DC RS－422） Each channel of time code output can be accessed 8 A time service device .