The manufacturer sells GPS Beidou satellite synchronous clock directlyThe manufacturer sells GPS Beidou satellite synchronous clock directly
The manufacturer sells GPS Beidou satellite synchronous clock directlyThe manufacturer sells GPS Beidou satellite synchronous clock directly
The manufacturer sells GPS Beidou satellite synchronous clock directly, and the manufacturer sells GPS Beidou satellite synchronous clock directly.
1. Overview
In modern power grid, a unified time system is of great significance for power system fault analysis, monitoring control and operation management. Substation timing refers to the synchronization process between the protection, measurement and monitoring equipment in the substation and the time protection of standard clock source, which ensures the consistency of real-time data acquisition in power system and provides an accurate time basis for system fault analysis and processing. Improve the efficiency and reliability of power grid operation, improve the level of Power Grid Accident Analysis and stability control, improve the accuracy of line fault location, phasor and power angle dynamic monitoring, unit and grid parameter verification.
Conventional transformers are used in traditional substations, and the transmission delay of primary and secondary electrical quantities is negligible. As long as the secondary electrical quantities of relevant TA and TV are sampled at a certain time according to the sampling pulses of automatic devices such as relay protection, the simultaneity of data can be guaranteed. The data acquisition module of automation equipment such as relay protection in intelligent substation moves forward to the merging unit. The primary electrical quantity of transformer needs to be collected by the front-end module and then processed by the merging unit. Because the acquisition and processing links of each interval transformer are independent of each other, there is no unified coordination, and the transmission of primary and secondary electrical quantities adds a delay link, resulting in the output data of each interval electronic transformer is not synchronous and can not be directly used in the protection calculation which requires high data synchronization. It can be seen that clock synchronization is the basis of ensuring network sampling synchronization. In power system, merging unit, synchronous phasor measurement device, fault recorder, electrical measurement and control unit, remote terminal, integrated protection and measurement and control device, computer protection device, safety automatic device, energy acquisition device, main station of computer monitoring system, distribution network terminal device and distribution network automation system all need to be imported. For row-to-row timing, these devices require time synchronization accuracy as shown in Table 1:
1.1 Basic Concept of Time
Time is a basic parameter of physics and one of the basic forms of matter existence. It is the fourth dimension of so-called space coordinates. Time represents the continuity of material movement and the sequence and duration of events. Its greatest feature is that it is impossible to keep constant.
Here are several different timing methods:
1. Universal Time: UT/UT0/UT1/UT2
The astronomical community will call the time of the flat sun from midnight, which is observed by the Greenwich Observatory in the United Kingdom, UT, and it has been used up to now.
The world directly obtained by observing stars is called UT0.
The earth's rotation axis is not fixed, so it is necessary to correct UT0 by polar shift, and record the world time obtained by polar shift correction as UT1, then UT1 = UT0 + lambda.
The earth's rotation rate is changing irregularly, and the rotation rate is slowing down. UT2 can be obtained by correcting the periodic variation of the earth's rotation rate for UT1. That is UT2 = UT1 + Ts = UT0 + lambda + Ts.
2. ATOMIC TIME/INTERNATIONAL ATOMIC TIME: TA/TAI
The study of atomic physics and quantum physics tells us that the energy level transitions occur in the peripheral electrons of the nucleus. The frequency standard is the frequency standard of the atom when it transits from the high level to the low level. That is the so-called atomic frequency standard (atomic frequency standard). The time measurement system based on atomic frequency standard is called atomic time, abbreviated as TA.
When the atom established by the International Time Bureau was designated as the International Atomic by the International Conference on Metrology, it was named TAI.
3. Coordinated Universal Time: UTC
The coordinated world time (UTC) is mainly used in China's power system, which represents the combination of the two time scales of IAT TAI and UT1. UTC is defined as
UTC (t) - TAI (t) = N seconds (N is an integer)
|UTC(t)—UT1(t)|＜0.9s
The specific implementation method of UTC is to cancel frequency offset adjustment, make UTC second length equal to TAI second length strictly, and make UTC close to UT1 in time. The difference between UT1 and TAI caused by the uneven rotation rate of the earth is compensated by adding 1 s or subtracting 1 s of leap seconds (i.e. hop seconds) in UTC time. Leap seconds are scheduled for 30 June or 31 December, that is to say, the last minute of UTC on 30 June or 31 December is 61 s or 59 s. Because of the inhomogeneity of the earth's rotation speed, the world time has been about 1 s slower than the atomic time in the past 20 years, and the difference between them has accumulated year by year, reaching 35 s by 2013.
1.2 Common Time Service System
The clock source is used to provide standard clock signals. The time service system mainly includes wireless time service and wired time service. Wireless time service system includes GPS (Global Positioning System) navigation system in the United States, Galileo navigation system in Europe, Beidou navigation system in China and GLINASS in Russia, etc. Cable time service system takes network or dedicated line as carrier, such as communication network time service system. At present, the main clock sources used in substations are GPS satellite timing and Beidou timing technology.
1. Overview
In modern power grid, a unified time system is of great significance for power system fault analysis, monitoring control and operation management. Substation timing refers to the synchronization process between the protection, measurement and monitoring equipment in the substation and the time protection of standard clock source, which ensures the consistency of real-time data acquisition in power system and provides an accurate time basis for system fault analysis and processing. Improve the efficiency and reliability of power grid operation, improve the level of Power Grid Accident Analysis and stability control, improve the accuracy of line fault location, phasor and power angle dynamic monitoring, unit and grid parameter verification.
Conventional transformers are used in traditional substations, and the transmission delay of primary and secondary electrical quantities is negligible. As long as the secondary electrical quantities of relevant TA and TV are sampled at a certain time according to the sampling pulses of automatic devices such as relay protection, the simultaneity of data can be guaranteed. The data acquisition module of automation equipment such as relay protection in intelligent substation moves forward to the merging unit. The primary electrical quantity of transformer needs to be collected by the front-end module and then processed by the merging unit. Because the acquisition and processing links of each interval transformer are independent of each other, there is no unified coordination, and the transmission of primary and secondary electrical quantities adds a delay link, resulting in the output data of each interval electronic transformer is not synchronous and can not be directly used in the protection calculation which requires high data synchronization. It can be seen that clock synchronization is the basis of ensuring network sampling synchronization. In power system, merging unit, synchronous phasor measurement device, fault recorder, electrical measurement and control unit, remote terminal, integrated protection and measurement and control device, computer protection device, safety automatic device, energy acquisition device, main station of computer monitoring system, distribution network terminal device and distribution network automation system all need to be imported. For row-to-row timing, these devices require time synchronization accuracy as shown in Table 1:
1.1 Basic Concept of Time
Time is a basic parameter of physics and one of the basic forms of matter existence. It is the fourth dimension of so-called space coordinates. Time represents the continuity of material movement and the sequence and duration of events. Its greatest feature is that it is impossible to keep constant.
Here are several different timing methods:
1. Universal Time: UT/UT0/UT1/UT2
The astronomical community will call the time of the flat sun from midnight, which is observed by the Greenwich Observatory in the United Kingdom, UT, and it has been used up to now.
The world directly obtained by observing stars is called UT0.
The earth's rotation axis is not fixed, so it is necessary to correct UT0 by polar shift, and record the world time obtained by polar shift correction as UT1, then UT1 = UT0 + lambda.
The earth's rotation rate is changing irregularly, and the rotation rate is slowing down. UT2 can be obtained by correcting the periodic variation of the earth's rotation rate for UT1. That is UT2 = UT1 + Ts = UT0 + lambda + Ts.
2. ATOMIC TIME/INTERNATIONAL ATOMIC TIME: TA/TAI
The study of atomic physics and quantum physics tells us that the energy level transitions occur in the peripheral electrons of the nucleus. The frequency standard is the frequency standard of the atom when it transits from the high level to the low level. That is the so-called atomic frequency standard (atomic frequency standard). The time measurement system based on atomic frequency standard is called atomic time, abbreviated as TA.
When the atom established by the International Time Bureau was designated as the International Atomic by the International Conference on Metrology, it was named TAI.
3. Coordinated Universal Time: UTC
The coordinated world time (UTC) is mainly used in China's power system, which represents the combination of the two time scales of IAT TAI and UT1. UTC is defined as
UTC (t) - TAI (t) = N seconds (N is an integer)
|UTC(t)—UT1(t)|＜0.9s
The specific implementation method of UTC is to cancel frequency offset adjustment, make UTC second length equal to TAI second length strictly, and make UTC close to UT1 in time. The difference between UT1 and TAI caused by the uneven rotation rate of the earth is compensated by adding 1 s or subtracting 1 s of leap seconds (i.e. hop seconds) in UTC time. Leap seconds are scheduled for 30 June or 31 December, that is to say, the last minute of UTC on 30 June or 31 December is 61 s or 59 s. Because of the inhomogeneity of the earth's rotation speed, the world time has been about 1 s slower than the atomic time in the past 20 years, and the difference between them has accumulated year by year, reaching 35 s by 2013.
1.2 Common Time Service System
The clock source is used to provide standard clock signals. The time service system mainly includes wireless time service and wired time service. Wireless time service system includes GPS (Global Positioning System) navigation system in the United States, Galileo navigation system in Europe, Beidou navigation system in China and GLINASS in Russia, etc. Cable time service system takes network or dedicated line as carrier, such as communication network time service system. At present, the main clock sources used in substations are GPS satellite timing and Beidou timing technology.
