CN110492966B - Time synchronization method of distributed relay protection device - Google Patents
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Abstract
The invention provides a time synchronization method of a distributed relay protection device, which realizes the accurate positioning of a second edge by utilizing a crystal oscillator counter between a host machine and a sub machine, the next second interval, the next second sampling value sending interval and the next second remainder equipartition interval are calculated by a second interval calculation method and a remainder equipartition algorithm in the second interval, the problems that the time scale discrete performance is greatly fluctuated in the time synchronization process and the host machine and the sub machine cannot carry out high-precision time synchronization without GPS signals are solved, the discrete value of the sampling value sending interval is kept at nanosecond level by the residue number average algorithm in the second interval, the stability of the sampling value sending period is greatly improved, and no external GPS signal is needed, high-precision time synchronization between the distributed host machine and the sub machine of the relay protection device can be realized, and the reliability of relay protection is improved.
Description
Technical Field
The invention relates to the technical field of power communication, in particular to a time synchronization method of a distributed relay protection device.
Background
With the rapid development of communication technology, the form of relay protection devices has been developed from centralized type to distributed type. The distributed relay protection host machine and the distributed relay protection sub machine are distributed and work cooperatively, data collected by the distributed relay protection host machine and the distributed relay protection sub machine are shared through optical fibers, and high-precision time synchronization needs to be achieved between the host machine and the sub machine, so that high-precision data synchronization of the host machine and the sub machine is guaranteed.
In the prior art, the time synchronization method of the main machine and the sub machine of the relay protection device comprises the following two methods:
1. the method is characterized in that a total station GPS clock is used, a host machine and a sub machine are respectively connected with a GPS clock source and perform time synchronization with a GPS, a large amount of hardware resources are consumed, and the host machine and the sub machine cannot realize time synchronization under the condition that a GPS signal fails;
2. the method is based on UDP/IP protocol, time synchronization error is large, and the requirement of high-precision time synchronization between distributed relay protection devices cannot be met.
The traditional way for time synchronization of two system nodes is mainly that a child node receives a time frame of a main node, compensates transmission delay according to a certain algorithm, and then updates the time of the child node to be consistent with the time of the main node. In this way, high-precision time synchronization can be performed, but the discrete performance of the time scale of the child node greatly fluctuates during synchronization. In the field of relay protection, such large fluctuation cannot be accepted, for example, the transmission interval of a sampling point requires that the discrete performance is not more than 10us under any condition, so that a distributed time synchronization method for a relay protection device is urgently needed, and high-precision time synchronization can be realized between a host machine and a sub machine under the condition that the relay protection device does not rely on external time synchronization.
Disclosure of Invention
The invention aims to provide a time synchronization method of a distributed relay protection device, which aims to solve the problems that the time scale dispersion performance is greatly fluctuated in the time synchronization process in the prior art and a host machine and a sub machine cannot carry out high-precision time synchronization without a GPS signal, improve the stability of a sampling value sending period, do not need to use an external GPS signal and improve the reliability of relay protection.
In order to achieve the above technical object, the present invention provides a time synchronization method for a distributed relay protection device, including the following operations:
protecting a submachine to receive a synchronous frame of the host, representing the size of an interval by counting a crystal oscillator of the submachine, respectively calculating a next second interval, a next second sampling value sending interval and a next second remainder equipartition interval according to the interval between adjacent synchronous frame second edges sent by the host and the interval between the host synchronous frame second edges and the local second edges, controlling the next second interval and the sampling value sending interval according to the next second interval and the next second interval, temporarily adding 1 to the sampling value sending interval every other remainder equipartition interval, and enabling the submachine and the host second edges to be synchronous and keeping the discrete value of the sampling value sending interval at a nanosecond level;
and the protecting sub-machine receives the time-setting frame of the main machine, and updates the clock information carried in the time-setting frame of the main machine to the sub-machine after the second edges of the sub-machine and the main machine are synchronous.
Preferably, the synchronization frame format includes a frame type, a frame length, a transmission delay, and a transmission delay.
Preferably, the time frame includes a frame type, a frame length, and a host clock.
Preferably, the next second interval, the next second sampling value sending interval and the next second remainder averaging interval are calculated as follows:
assuming that the number of the next host synchronous frame received by the protection sub-machine is 3, when the next second is over, the crystal oscillator counter value of the second edge corresponding to the host synchronous frame 4 is predicted as follows:
T3＝BT1+2×(BT1-BT0)
wherein BT0 is the value of the sub-machine crystal oscillator protection counter corresponding to the host synchronization frame 1, and BT1 is the value of the sub-machine crystal oscillator protection counter corresponding to the host synchronization frame 2;
the crystal oscillator counter value of the slave unit at the second edge of the slave unit at the end of the second is predicted as follows:
T2＝(T1+DT1)
t1 is the crystal oscillator counter value of the second edge when one second ends on the submachine, and DT1 is the second interval of the submachine per second;
the next second interval of the submachine is the difference of the counter values of the crystal oscillators corresponding to the two second edges:
DTs＝T3-T2＝BT1+2×(BT1-BT0)-(T1+DT1)
when the number of sampling points of the slave unit in the next second is known to be Nsv, the next-second sampling value sending interval is:
DTsv＝DTs/Nsv
the remainder is compensated evenly over one second interval, the next second remainder average interval being:
DTy＝DTs/Ny＝DTs/(DTs-(DTsv×Nsv))。
preferably, the master machine sends the synchronization frame to the slave machine once per second, and sends a time-alignment frame to the slave machine 500ms after the second edge.
Preferably, the discrete value of the sampling value transmission interval is 1 crystal oscillation period, which is in the order of nanoseconds.
Preferably, BT1-BT0 is checked for validity for a host sync framesecond interval before calculating a next second interval, a next second sample transmission interval, and a next second remainder averaging interval.
Preferably, the clock information carried in the time frame by the master is the UTC second value, and the following operations are simultaneously required to determine the millisecond time of the slave unit: when the second edge of the submachine comes, setting the millisecond value to 0
The effect provided in the summary of the invention is only the effect of the embodiment, not all the effects of the invention, and one of the above technical solutions has the following advantages or beneficial effects:
compared with the prior art, the invention realizes the accurate positioning of the second edge by utilizing the crystal oscillator counter between the host machine and the submachine, and realizes the calculation of the next second interval, the next second sampling value sending interval and the next second remainder averaging interval by utilizing the second interval calculation method and the remainder averaging algorithm in the second interval, thereby solving the problems that the time scale dispersion performance is greatly fluctuated in the time synchronization process and the host machine and the submachine can not carry out high-precision time synchronization without GPS signals.
Drawings
Fig. 1 is a schematic diagram of formats of a synchronization frame and a time frame between a host and a slave in the embodiment of the present invention;
fig. 2 is a schematic diagram of second edge synchronization between the slave machine and the master machine according to an embodiment of the present invention;
fig. 3 is a logic flow diagram of a second edge synchronization between the slave machine and the master machine according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a sub-machine refresh clock according to an embodiment of the present invention;
fig. 5 is a logic flow diagram of a sub-machine update clock provided in the embodiment of the present invention.
Detailed Description
In order to clearly explain the technical features of the present invention, the following detailed description of the present invention is provided with reference to the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be noted that the components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and procedures are omitted so as to not unnecessarily limit the invention.
The following describes a time synchronization method of a distributed relay protection device according to an embodiment of the present invention in detail with reference to the accompanying drawings.
The embodiment of the invention discloses a time synchronization method of a distributed relay protection device, which comprises the following operations:
protecting a submachine to receive a synchronous frame of the host, representing the size of an interval by counting a crystal oscillator of the submachine, respectively calculating a next second interval, a next second sampling value sending interval and a next second remainder equipartition interval according to the interval between adjacent synchronous frame second edges sent by the host and the interval between the host synchronous frame second edges and the local second edges, controlling the next second interval and the sampling value sending interval according to the next second interval and the next second interval, temporarily adding 1 to the sampling value sending interval every other remainder equipartition interval, and enabling the submachine and the host second edges to be synchronous and keeping the discrete value of the sampling value sending interval at a nanosecond level;
and the protecting sub-machine receives the time-setting frame of the main machine, and when the second edges of the sub-machine and the main machine are synchronous, the clock information carried in the time-setting frame of the main machine is updated to the sub-machine.
The frame formats for protecting the time synchronization of the master machine and the slave machine are divided into two types, namely a synchronization frame and a time synchronization frame, as shown in fig. 1. The synchronous frame format includes a frame type, a frame length, a transmission delay, and a transmission delay, for example, the frame type is fixed as a; the frame length is fixed to 8 bytes; the sending delay is dynamically filled when the host sends the synchronous frame, is the time delay from the second edge of the protection host to the beginning of sending the synchronous frame by the protection host, is expressed by the number of the oscillation periods of the crystal oscillator, and is filled by the host according to the actual condition; the transmission delay is determined by a transmission medium between the main machine and the sub machine, and is the time delay from the start of sending the synchronous frame by the protection main machine to the completion of receiving the synchronous frame by the protection sub machine through configuration file configuration and is represented by the number of crystal oscillator oscillation periods. The time frame includes a frame type, a frame length, and a host clock, for example, the frame type is fixed to B, the frame length is fixed to 8 bytes, and the host clock is the second of UTC time.
Assuming that the frequency of the crystal oscillators protecting the master machine and the slave machine is 50000000Hz, the value of the crystal oscillator counter is increased by 1 in each oscillation period, and when the value of the crystal oscillator counter is greater than 49999999, the inversion is 0, and the timing system is based on three parameters: a second interval DTs, a sample value transmission interval DTsv, and a remainder averaging interval DTy. The second interval is the number of the crystal oscillator oscillation cycles in one second, the number of the crystal oscillator oscillation cycles in the next second is calculated, the second interval of the next second is obtained, and if the sub machine never receives the time synchronization signal of the main machine, the number of the crystal oscillator oscillation cycles in one second is 50000000. The sampling sending interval is the number of crystal oscillation periods contained in the sampling value sending period of the submachine. The remainder equipartition interval is the number of crystal oscillation periods contained in the remainder equipartition period within one second.
The master machine informs the slave machine of the occurrence of the second edge by issuing a synchronous frame to the slave machine when the second edge occurs. The master machine sends a synchronous frame to the submachine every second, and sends a time-to-time frame to the submachine 500ms after the second edge, so that the time information of the submachine in seconds and above is updated. The submachine calculates the second interval DTs of the submachine in the next second by calculating the interval between adjacent synchronous frame second edges sent by the main machine and the interval between the synchronous frame second edges of the main machine and the second edge of the local machine, and simultaneously calculates the sending interval DTsv and the remainder sharing interval DTy of the sampling point in the next second based on a remainder sharing algorithm, wherein the sending interval of the sampling value is temporarily adjusted to DTsv +1 at every other remainder sharing interval, the discrete value of the sending interval of the sampling value is 1 crystal oscillator oscillation period and is in nanosecond level, when the next second is finished, the alignment of the second edge of the submachine and the second edge of the main machine is realized, and after the second edges are aligned, the submachine updates the time of the local machine by reading time alignment frames.
As shown in fig. 2 and 3, when the master synchronization frame 1 arrives, the protection slave machine compensates the transmission delay and the transmission delay in the protection master synchronization frame to obtain a protection slave machine crystal oscillator counter value BT 0; when the host synchronization frame 2 arrives, the protection sub-machine compensates the transmission delay and the transmission delay in the protection host synchronization frame to obtain a crystal oscillator counter value BT1 of the protection sub-machine, checks whether the second interval BT1-BT0 of the host synchronization frame is effective, if not, continuously records the crystal oscillator counter value of the protection sub-machine when the synchronization frame arrives, and if so, continuously performs the following steps: at the end of the previous second, the crystal counter value corresponding to the second edge is T1, the second interval of the known protection sub-machine per second is DT1, and the crystal counter prediction of the second edge corresponding to the host synchronization frame 4 at the end of the next synchronization frame is:
T3＝BT1+2×(BT1-BT0)
the value prediction of the crystal oscillator counter corresponding to the slave unit second edge 3 at the end of the slave unit second is as follows:
T2＝(T1+DT1)
the difference of the crystal oscillator counters corresponding to two second edges at the next second interval of the submachine is as follows:
DTs＝T3-T2＝BT1+2×(BT1-BT0)-(T1+DT1)
if the number of sampling points of the slave unit in the next second is Nsv, the transmission interval of the sampling values in the next second is:
DTsv＝DTs/Nsv
since DTs and Nsv are both integer data types, the remainder Ny obtained by dividing DTs by Nsv is:
Ny＝DTs-(DTsv×Nsv)
in order to ensure the discrete performance of the sampling interval, the remainder is uniformly compensated within one second interval, and the next second remainder average interval is as follows:
DTy＝DTs/Ny＝DTs/(DTs-(DTsv×Nsv))
calculating next second interval DTs, next second sampling value sending interval DTsv and next second remainder equipartition interval DTy respectively, after the second is finished, the submachine controls the next second interval according to the DTs calculated by the second, and controls the next second sampling value sending interval according to the DTsv calculated by the second; on the basis, the sampling value sending interval is temporarily adjusted to DTsv +1 every other remainder sharing interval in the next second and is executed circularly.
As shown in fig. 4 and 5, the slave unit receives the time tick frame of the master unit and updates the time. Setting the millisecond value as 0 every time the second edge of the submachine comes; after the sub-machine receives the time-tick frame of the main machine, if the second edges of the sub-machine and the main machine are synchronized, the clock information carried in the time-tick frame of the main machine is updated to the sub-machine, if the second edges of the sub-machine and the main machine are not synchronized, when the second edge of the sub-machine comes, the millisecond value is set to be 0, and the operation is carried out in a circulating mode.
According to the embodiment of the invention, the accurate positioning of the second edge is realized between the host machine and the submachine by using the crystal oscillator counter, the calculation of the next second interval, the next second sampling value sending interval and the next second remainder averaging interval is realized by the second interval calculation method and the remainder averaging algorithm in the second interval, the problems that the time scale dispersion performance is greatly fluctuated in the time synchronization process and the host machine and the submachine cannot carry out high-precision time synchronization without GPS signals are solved, the dispersion value of the sampling value sending interval is kept at a nanosecond level by the remainder averaging algorithm in the second interval, the stability of the sampling value sending period is greatly improved, the external GPS signals are not needed, the high-precision time synchronization between the distributed host machine and the submachine of the relay protection device can be realized, and the reliability of the relay protection is improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (7)
1. A time synchronization method of a distributed relay protection device is characterized by comprising the following operations:
the protection sub-machine receives the synchronous frame of the main machine, the interval size is represented by sub-machine crystal oscillator counting, the next second interval, the next second sampling value sending interval and the next second remainder equipartition interval are respectively calculated according to the interval between the adjacent synchronous frame second edges sent by the main machine and the interval between the main machine synchronous frame second edges and the local machine second edges, and the calculation process is as follows:
assuming that the number of the next host synchronous frame received by the protection sub-machine is 3, when the next second is over, the crystal oscillator counter value of the second edge corresponding to the host synchronous frame 4 is predicted as follows:
T3＝BT1+2×(BT1-BT0)
wherein BT0 is the value of the sub-machine crystal oscillator protection counter corresponding to the host synchronization frame 1, and BT1 is the value of the sub-machine crystal oscillator protection counter corresponding to the host synchronization frame 2;
the crystal oscillator counter value of the slave unit at the second edge of the slave unit at the end of the second is predicted as follows:
T2＝(T1+DT1)
t1 is the crystal oscillator counter value of the second edge when one second ends on the submachine, and DT1 is the second interval of the submachine per second;
the next second interval of the submachine is the difference of the counter values of the crystal oscillators corresponding to the two second edges:
DTs＝T3-T2＝BT1+2×(BT1-BT0)-(T1+DT1)
when the number of sampling points of the slave unit in the next second is known to be Nsv, the next-second sampling value sending interval is:
DTsv＝DTs/Nsv
wherein DTsv is an integer obtained by dividing DTs by Nsv;
the remainder is compensated evenly over one second interval, the next second remainder average interval being:
DTy＝DTs/Ny＝DTs/(DTs-(DTsv×Nsv))
wherein Ny is the remainder of dividing DTs by Nsv;
controlling the second interval and the sampling value sending interval of the next second according to the control, temporarily adding 1 to the sampling value sending interval every other remainder evenly-divided interval, so that the second edges of the submachine and the host machine are synchronous, and the discrete value of the sampling value sending interval is kept at the nanosecond level;
and the protecting sub-machine receives the time-setting frame of the main machine, and updates the clock information carried in the time-setting frame of the main machine to the sub-machine after the second edges of the sub-machine and the main machine are synchronous.
2. The time synchronization method of a distributed relay protection device according to claim 1, wherein the synchronization frame format includes a frame type, a frame length, a transmission delay, and a transmission delay.
3. The time synchronization method of a distributed relay protection device according to claim 1, wherein the time frame includes a frame type, a frame length, and a host clock.
4. The time synchronization method of the distributed relay protection device according to claim 1, wherein the host sends a synchronization frame to the slave unit once per second, and sends a time alignment frame to the slave unit 500ms after the second edge.
5. The time synchronization method of a distributed relay protection device according to claim 1, wherein a discrete value of the sampling value transmission interval is 1 crystal oscillation period, which is in the order of nanoseconds.
6. The time synchronization method of a distributed relay protection device according to claim 1, wherein it is necessary to check whether BT1-BT0 is valid for the host synchronization frame second interval before calculating the next second interval, the next second sampling value transmission interval, and the next second remainder equipartition interval.
7. The time synchronization method of a distributed relay protection device according to claim 1, wherein the clock information carried in the time frame by the host is the UTC second value, and the following operations are performed to determine the millisecond time of the slave unit: when the slave unit second edge comes, the millisecond value is set to 0.
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| JP2015198294A (en) * | 2014-03-31 | 2015-11-09 | 日本電波工業株式会社 | oscillation device |
| CN104536285B (en) * | 2014-11-25 | 2017-08-08 | 许继电气股份有限公司 | A kind of efficient crystal oscillator frequency timekeeping method |
| CN109814835B (en) * | 2019-01-30 | 2022-02-18 | 郑州云海信息技术有限公司 | FPGA-based interval uniform distribution device and IP core |
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| CN107453831A (en) * | 2016-05-31 | 2017-12-08 | 阿里巴巴集团控股有限公司 | The method for synchronizing time and device of distributed transaction system |
| CN107656151A (en) * | 2017-08-10 | 2018-02-02 | 国家电网公司 | Realize full-time sequence grid measurement data synchronized sampling and the investigating method of processing |
| CN109425844A (en) * | 2017-08-30 | 2019-03-05 | 北京智云芯科技有限公司 | A kind of calibration method and system of data sampling |
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