[go: up one dir, main page]

CN114487702B - A method for accurate time synchronization of distribution network fault indicators based on acquisition system - Google Patents

A method for accurate time synchronization of distribution network fault indicators based on acquisition system Download PDF

Info

Publication number
CN114487702B
CN114487702B CN202210019806.XA CN202210019806A CN114487702B CN 114487702 B CN114487702 B CN 114487702B CN 202210019806 A CN202210019806 A CN 202210019806A CN 114487702 B CN114487702 B CN 114487702B
Authority
CN
China
Prior art keywords
time
collection unit
synchronization
data frame
clock
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202210019806.XA
Other languages
Chinese (zh)
Other versions
CN114487702A (en
Inventor
唐金锐
李振海
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wuhan University of Technology WUT
Original Assignee
Wuhan University of Technology WUT
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wuhan University of Technology WUT filed Critical Wuhan University of Technology WUT
Priority to CN202210019806.XA priority Critical patent/CN114487702B/en
Publication of CN114487702A publication Critical patent/CN114487702A/en
Application granted granted Critical
Publication of CN114487702B publication Critical patent/CN114487702B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/088—Aspects of digital computing

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

本发明提出了一种基于采集系统的配电网故障指示器精确时间同步方法。采集系统包括采集单元、汇集单元。汇集单元计算首先采集单元的频偏变化率，根据采集单元的频偏变化率计算采集单元的频偏变化率时钟误差，根据采集单元的频偏变化率计算采集单元的同步时间数据帧发送最大间隔时间；然后根据配电线路电流的实时有效值调整汇集单元的广播时间同步数据帧的周期；最后在广播时间同步数据帧的周期内，通过极大似然估计算法对汇集单元与采集单元之间发送同步时间数据帧请求和应答的时刻进行计算，得到采集单元在该广播时间同步数据帧周期内的相位偏差和频偏的估算，修正采集单元在该广播时间同步数据帧周期内的初始相位和时钟频率。

The present invention proposes a method for accurate time synchronization of a distribution network fault indicator based on a collection system. The collection system includes a collection unit and a collection unit. The collection unit first calculates the frequency deviation change rate of the collection unit, calculates the frequency deviation change rate clock error of the collection unit according to the frequency deviation change rate of the collection unit, and calculates the maximum interval time for sending the synchronization time data frame of the collection unit according to the frequency deviation change rate of the collection unit; then adjusts the period of the broadcast time synchronization data frame of the collection unit according to the real-time effective value of the distribution line current; finally, within the period of the broadcast time synchronization data frame, the time of sending the synchronization time data frame request and response between the collection unit and the collection unit is calculated by the maximum likelihood estimation algorithm, and the phase deviation and frequency deviation of the collection unit within the period of the broadcast time synchronization data frame are estimated, and the initial phase and clock frequency of the collection unit within the period of the broadcast time synchronization data frame are corrected.

Description

Accurate time synchronization method for power distribution network fault indicator based on acquisition system
Technical Field
The invention belongs to the technical field of power distribution networks, and particularly relates to a power distribution network fault indicator accurate time synchronization method based on an acquisition system.
Background
The distribution network is a link directly facing users in the power system, and has direct influence on the reliability of power supply of the users. The distribution line is an important component part of the distribution network, has a plurality of topological branches, has a severe running environment, is difficult to quickly find and determine the fault position once the fault occurs, and seriously affects the improvement of the power supply reliability.
The distribution network fault indicator is an important component of a distribution automation system and can be conveniently mounted on a distribution line. Once a short-circuit fault or a single-phase ground fault occurs, the fault location of the distribution network can be realized.
The power distribution network fault indicator system consists of a background positioning system, a collecting unit and an acquisition unit. In order to realize accurate and reliable fault location, each collecting unit and 3 matched collecting units are required to meet accurate time synchronization so as to ensure the accuracy of synchronous sampling of each phase of current and zero sequence current synthesis.
In the fault indicator system of the power distribution network, each collecting unit directly adopts a high-power-consumption time synchronization technology, such as GPS/Beidou, so as to realize accurate time synchronization. And each collecting unit and 3 matched collecting units are used for regularly broadcasting synchronous time data frames in the conventional method, and after the 3 matched collecting units receive the broadcasted synchronous time frames, the collecting units perform respective time calibration to finish time synchronization. The field operation result shows that:
After the traditional time synchronization method is adopted, the time synchronization error between each collecting unit and the 3 matched collecting units is about 100 milliseconds;
The current of the distribution line terminal and the branch line can not meet the requirement of periodically realizing time synchronization of the acquisition unit and the collecting unit due to small line load current.
At this time, the power distribution network fault indicator system cannot realize high-precision fault section positioning based on transient current sampling values.
Disclosure of Invention
The invention aims to provide an accurate time synchronization method of a power distribution network fault indicator based on an acquisition system, which can be used for greatly improving the time synchronization precision between each collecting unit and 3 acquisition units matched with each collecting unit in the power distribution network fault indicator system so as to overcome the problems in the background technology.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
the acquisition system comprises an acquisition unit and a collection unit;
the collecting unit is connected with the collecting unit in a wireless mode;
the accurate time synchronization method of the power distribution network fault indicator comprises the following steps:
the collecting unit is used for collecting the real-time current of the distribution line in real time and wirelessly transmitting the real-time current to the collecting unit, and the collecting unit calculates the real-time effective value of the current of the distribution line according to the real-time current of the distribution line;
Step 2, the collecting unit calculates the frequency offset change rate of the collecting unit, calculates the clock error of the frequency offset change rate of the collecting unit according to the frequency offset change rate of the collecting unit, calculates the maximum interval time of sending the synchronous time data frame of the collecting unit according to the frequency offset change rate of the collecting unit, and sets the period of the broadcasting time synchronous data frame of the collecting unit according to the real-time effective value of the current of the distribution line and the maximum interval time of sending the synchronous time data frame of the collecting unit;
Step 3, in the period of the broadcast time synchronous data frame, the collecting unit sends a synchronous time data frame request to the collecting unit, and after the collecting unit receives the synchronous time data frame request, the collecting unit further sends a synchronous time data frame response to the collecting unit;
preferably, the distribution line real-time current in step 1 is:
X(1),X(2),X(3),X(4),......,X(NTs)
Wherein X (k) represents the current at the moment of the distribution line k, N Ts represents the number of sampling moments, and k epsilon [1, N Ts ];
The real-time effective value of the distribution line current obtained by calculation in the step1 is as follows:
Wherein X (k) represents the current at the moment of the distribution line k, and X (eq) represents the real-time effective value of the distribution line current;
Preferably, in step 2, the frequency offset change rate of the calculation and acquisition unit is:
Clock synchronization is respectively carried out between the acquisition unit and the collecting unit at t i、ti+1、ti+2;
the time offset of the acquisition unit due to the frequency offset during the period Δt i+1＝ti+1-ti is expressed as:
θ(ti+1)＝[T'(ti+1)-T'(ti)]-(ti+1-ti)
In the above formula, T i+1 represents the time of the collecting unit in the process of the i+1th clock synchronization, T i represents the time of the collecting unit in the process of the i-th clock synchronization, T '(T i+1) represents the time of the collecting unit in the process of the i+1th clock synchronization, and T' (T i) respectively represents the time of the collecting unit in the process of the i-th clock synchronization;
the time offset of the acquisition unit due to the frequency offset in the period of Δt i+2＝ti+2-ti+1 is expressed as:
θ(ti+2)＝[T'(ti+2)-T'(ti+1)]-(ti+2-ti+1)
In the above formula, T i+2 represents the time of the collecting unit in the i+2th clock synchronization process, T i+1 represents the time of the collecting unit in the i+1th clock synchronization process, T '(T i+2) represents the time of the collecting unit in the i+2th clock synchronization process, and T' (T i+1) represents the time of the collecting unit in the i+1th clock synchronization process;
The frequency offset change rate of the acquisition unit in the step2 is as follows:
wherein, gamma represents the frequency offset change rate of the acquisition unit in the step 2;
And step2, calculating the clock error of the frequency offset change rate of the acquisition unit, wherein the clock error is as follows:
in the above formula, T op represents an operation time period, and e represents a clock error;
and step 2, calculating the maximum interval time of the synchronous time data frame transmission of the acquisition unit as follows:
in the above description, T int.max represents the maximum interval time of sending the synchronous time data frame of the acquisition unit, and E L.max represents the minimum requirement of accurate fault location on the time synchronization error between the power distribution network fault indicator collection unit and the acquisition unit;
And step 2, setting the period of the broadcasting time synchronous data frame of the aggregation unit as follows:
in the above formula, T int.per represents a period of a broadcast time synchronization data frame of the sink unit, X (eq) represents a real-time effective value of a distribution line current, I L.min represents a minimum current flowing through a distribution line corresponding to a normal operation of the fault indicator collection unit, I L.max represents a maximum current flowing through a distribution line corresponding to a normal operation of the fault indicator collection unit, T int.min represents a minimum period of a broadcast time synchronization data frame of the sink unit, and X (eq) represents a real-time effective value of a distribution line current;
preferably, in step 3, the time for transmitting the request and the response of the synchronous time data frame is calculated by using a maximum likelihood estimation algorithm, so as to obtain the estimation of the phase deviation and the frequency deviation of the acquisition unit in the broadcast time synchronous data frame period, which specifically includes:
According to the communication process between the collecting unit and the collecting unit, the calculation expressions of the moments T 1,i+1 and T 4,i+1 are obtained:
T1,i+1＝T2,i+1-d-xi+1+θB,i+1(T2,i+1-T4,i-d-xi+1)+θA,i+1
=(1+θB,i+1)(T2,i+1-T4,i-d-xi+1)+θA,i+1+T4,i
T4,i+1＝T3,i+1+d+yi+1+θB,i+1(T3,i+1-T4,i+d+yi+1)+θA,i+1
=(1+θB,i+1)(T3,i+1-T4,i+d+yi+1)+θA,i+1+T4,i
In the above formula, in the (i+1) clock synchronization process, the time from the response of the acquisition unit to the synchronization time data frame of the collection unit is T 1,i+1, the time from the response of the collection unit to the synchronization time data frame of the collection unit is T 2,i+1, the synchronization time data frame is sent to the collection unit, the time is T 3,i+1, and the time from the last collection unit to the synchronization time data frame sent back by the collection unit is T 4,i+1. Meanwhile, the estimation method also needs to use the time T 4,i when the acquisition unit receives the synchronous time data frame sent back by the aggregation unit in the ith clock synchronization process, d represents a determination part of path delay, x i+1 represents an uncertainty part of path delay when the acquisition unit sends the synchronous data frame to the aggregation unit in the ith clock synchronization process, the uncertainty part generally obeys random distribution, theta A,i+1 represents clock initial phase deviation existing between the aggregation unit and the acquisition unit in the ith clock synchronization process, theta B,i+1 represents frequency deviation between the aggregation unit and the acquisition unit in the ith clock synchronization process, theta B,i+1(T1,i+1-T4,i+d+xi+1) represents clock deviation caused by the frequency deviation, y i+1 represents an uncertainty part of path delay when the aggregation unit sends the synchronous data frame to the acquisition unit in the ith clock synchronization process, and the uncertainty part generally obeys random distribution.
Enabling S1＝T1,i+1-T4,i;S2＝T2,i+1-T4,i;S3＝T3,i+1-T4,i;S4＝T4,i+1-T4,i; to obtain an expression of initial clock phase deviation theta A,i+1 and frequency deviation theta B,i+1 existing between the collecting unit and the collecting unit in the (i+1) th clock synchronization process by using a maximum likelihood estimation method:
In the above formula, d represents a determination part of path delay, a calculation formula of d=l dis/vc,Ldis represents a distance between the collecting unit and the collecting unit, and vc represents a communication speed, which is generally taken as 3×10 8 m/s.
Step 3, the correction acquisition unit synchronizes the initial phase and the clock frequency in the data frame period at the broadcast time, specifically:
Adjusting the clock signal phase of the acquisition unit to be theta rev,i+1＝θinit,i+1+θA,i+1 by utilizing the obtained initial phase deviation theta A,i+1 of the clocks between the aggregation unit and the acquisition unit in the i+1th clock synchronization process, so as to ensure synchronization time synchronization, wherein theta init,i+1 is the initial phase of the acquisition unit in the i+1th clock synchronization process, and theta rev,i+1 is the adjusted phase of the acquisition unit in the i+1th clock synchronization process; and adjusting the clock frequency of the acquisition unit to be f rev,i+1＝finit,i+1+θB,i+1 by utilizing the obtained clock frequency deviation theta B,i+1 between the aggregation unit and the acquisition unit in the i+1th clock synchronization process, wherein f init,i+1 is the initial clock frequency of the acquisition unit in the i+1th clock synchronization process, and f rev,i+1 is the clock frequency of the acquisition unit after adjustment in the i+1th clock synchronization process. And finally, accurate time synchronization between the collecting unit and the collecting unit in the period of each broadcast time synchronization data frame is realized.
Therefore, the invention has the following advantages:
The accurate time synchronization method of the power distribution network fault indicator is based on the calculated frequency offset change rate between the collecting unit and the clock of the collecting unit and the load current flowing through the power distribution line, and can adaptively adjust the synchronization period of the broadcast time synchronization data frame between the collecting unit and the collecting unit, so that the time synchronization precision between the collecting unit and the collecting unit can be greatly improved on the premise of ensuring the normal energy supply of the collecting unit.
The accurate time synchronization method of the power distribution network fault indicator provided by the invention obtains the clock initial phase deviation and the frequency deviation existing between the collecting unit and the collecting unit at the starting moment of each synchronization period by utilizing the maximum likelihood estimation method in the time synchronization period of each collecting unit and the collecting unit, and accordingly, the clock of the collecting unit is corrected, and the accurate time synchronization precision between the collecting unit and the collecting unit in each self-adaptive synchronization period can be greatly improved.
Drawings
FIG. 1 is a flow chart of accurate time synchronization of fault indicators of a power distribution network according to the method of the invention
Fig. 2 is a schematic diagram of clock synchronization principle of a power distribution network fault indicator collecting unit and a collecting unit in a broadcast time synchronization data frame period.
FIG. 3 is a schematic diagram of a distribution network fault indicator collection unit and an acquisition unit according to the method of the present invention for broadcasting time synchronization data frames in the ith, the (i+1) and the (i+2) times.
Fig. 4 shows a principle of a synchronization process of a collection unit and an acquisition unit of the fault indicator of the power distribution network.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the present invention. In addition, the technical features described below in the various embodiments of the present invention may be combined with each other as long as they do not conflict with each other.
Embodiments of the present invention are described below with reference to fig. 1 to 4.
The system comprises an acquisition unit and a collection unit;
the collecting unit is connected with the collecting unit in a wireless mode;
The acquisition unit is an induction power-taking transient wave recording type fault indicator acquisition unit comprising a 433MHz wireless communication module;
The collecting unit comprises a 433MHz wireless communication module, a GPS module, a 2G/4G communication module and a fault indicator collecting unit of an optical storage power supply module;
a method for accurate time synchronization of fault indicators of a power distribution network is characterized by comprising the following steps,
The collecting unit is used for collecting the real-time current of the distribution line in real time and wirelessly transmitting the real-time current to the collecting unit, and the collecting unit calculates the real-time effective value of the current of the distribution line according to the real-time current of the distribution line;
The real-time current of the distribution line in the step 1 is as follows:
X(1),X(2),X(3),X(4),......,X(NTs)
Wherein X (k) represents the distribution line k moment current, N Ts = 1024 represents the number of sampling moments, k e [1, N Ts ];
The real-time effective value of the distribution line current obtained by calculation in the step1 is as follows:
Wherein, X (k) represents the current at the moment of the distribution line k, X (eq) represents the real-time effective value of the distribution line current, and X (eq) =30A is calculated at the moment;
Step 2, the collecting unit calculates the frequency offset change rate of the collecting unit, calculates the clock error of the frequency offset change rate of the collecting unit according to the frequency offset change rate of the collecting unit, calculates the maximum interval time of sending the synchronous time data frame of the collecting unit according to the frequency offset change rate of the collecting unit, and sets the period of the broadcasting time synchronous data frame of the collecting unit according to the real-time effective value of the current of the distribution line and the maximum interval time of sending the synchronous time data frame of the collecting unit;
in the step 2, the frequency offset change rate of the calculation acquisition unit is as follows:
Clock synchronization is respectively carried out between the acquisition unit and the collection unit at T i、ti+1、ti+2; the time of the pooling unit is respectively T i =12 30 minutes 53 seconds 867.5 microseconds, T i+1 =12 40 minutes 54 seconds 865.6 microseconds, T i+2 =12 50 minutes 54 seconds 880.5 microseconds, and the time of the collecting unit is respectively T ' (T i) =12 30 minutes 53 seconds 862.5 microseconds, T ' (T i+1) =12 40 minutes 54 seconds 861.6 microseconds, T ' (T i+2) =12 50 minutes 54 seconds 877.8 microseconds.
Then the acquisition unit shifts in time by the frequency offset by θ (t i+1)＝T'(ti+1)-T'(ti)-Δti+1 =1 microsecond) for a period of Δt i+1＝ti+1-ti =10 minutes 0 seconds 99998.1 microseconds and shifts in time by the frequency offset by θ (t i+2) =1.3 microseconds for a period of Δt i+2＝ti+2-ti+1.
The frequency offset change rate of the acquisition unit in the step2 is as follows:
setting the requirement E L.max of accurate fault location on time synchronization accuracy of 3 acquisition units to obtain 20 microseconds, wherein the maximum interval time for calculating the synchronization time data frame transmission of the acquisition units in the step 2 is as follows:
The calculation process of setting the period of the broadcast time synchronization data frame of the collecting unit in step 2 includes that I L.min represents the minimum current flowing through the distribution line corresponding to the fault indicator collecting unit in normal operation, which is taken as 3A, I L.max represents the current flowing through the distribution line corresponding to the fault indicator collecting unit when the induction power-taking energy reaches the maximum value, which is taken as 600A, and T int.min represents the minimum period of the broadcast time synchronization data frame of the collecting unit, which is generally taken as 5 minutes, namely 300s. Then, between the collecting unit and the 3 collecting units, according to the current flowing through the distribution line, the period T int.per of the broadcasting time synchronization data frame of the collecting unit is adaptively adjusted to be:
In the above equation, X (eq) represents the real-time effective value of the distribution line current, and if the real-time effective value is equal to 30A, the period T int.per of the adaptive adjustment sink unit broadcast time synchronization data frame is 6597s.
Step 3, in the period of the broadcast time synchronous data frame, the collecting unit sends a synchronous time data frame request to the collecting unit, and after the collecting unit receives the synchronous time data frame request, the collecting unit further sends a synchronous time data frame response to the collecting unit;
Step 3, calculating the time of sending the request and the response of the synchronous time data frame by using a maximum likelihood estimation algorithm, and obtaining the estimation of the phase deviation and the frequency deviation of the acquisition unit in the broadcasting time synchronous data frame period specifically comprises the following steps:
According to the communication process between the collecting unit and the collecting unit, the calculation expressions of the moments T 1,i+1 and T 4,i+1 are obtained:
T1,i+1＝T2,i+1-d-xi+1+θB,i+1(T2,i+1-T4,i-d-xi+1)+θA,i+1
=(1+θB,i+1)(T2,i+1-T4,i-d-xi+1)+θA,i+1+T4,i
T4,i+1＝T3,i+1+d+yi+1+θB,i+1(T3,i+1-T4,i+d+yi+1)+θA,i+1
=(1+θB,i+1)(T3,i+1-T4,i+d+yi+1)+θA,i+1+T4,i
In the above formula, in the (i+1) clock synchronization process, the time from the response of the acquisition unit to the synchronization time data frame of the collection unit is T 1,i+1, the time from the response of the collection unit to the synchronization time data frame of the collection unit is T 2,i+1, the synchronization time data frame is sent to the collection unit, the time is T 3,i+1, and the time from the last collection unit to the synchronization time data frame sent back by the collection unit is T 4,i+1. Meanwhile, the estimation method also needs to use the time T 4,i when the acquisition unit receives the synchronous time data frame sent back by the aggregation unit in the ith clock synchronization process, d represents a determination part of path delay, x i+1 represents an uncertainty part of path delay when the acquisition unit sends the synchronous data frame to the aggregation unit in the ith clock synchronization process, the uncertainty part generally obeys random distribution, theta A,i+1 represents clock initial phase deviation existing between the aggregation unit and the acquisition unit in the ith clock synchronization process, theta B,i+1 represents frequency deviation between the aggregation unit and the acquisition unit in the ith clock synchronization process, theta B,i+1(T1,i+1-T4,i+d+xi+1) represents clock deviation caused by the frequency deviation, y i+1 represents an uncertainty part of path delay when the aggregation unit sends the synchronous data frame to the acquisition unit in the ith clock synchronization process, and the uncertainty part generally obeys random distribution. in actual process, it is measured that T 1,i+1 =12, 40 minutes, 54 seconds and 865.400 microseconds, T 2,i+1 =12, 40 minutes, 54 seconds and 865.402 microseconds, T 3,i+1 =12, 40 minutes, 54 seconds and 865.403 microseconds, T 4,i+1 =12, 40 minutes, 54 seconds and 865.404 microseconds, and T 4,i =12, 30 minutes, 53 seconds and 867.500 microseconds.
Let S1＝T1,i+1-T4,i;S2＝T2,i+1-T4,i;S3＝T3,i+1-T4,i;S4＝T4,i+1-T4,i; be S 1＝T1,i+1-T4,i =10 minutes 999997.900 microseconds, S 2＝T2,i+1-T4,i =10 minutes 999997.902 microseconds, S 3＝T3,i+1-T4,i =10 minutes 999997.903 microseconds, S 4＝T4,i+1-T4,i =10 minutes 999997.904 microseconds. The determination part d of the calculation path delay, d=l dis/vc＝3.33×10-9s,Ldis, represents the distance 1m between the collecting unit and the acquisition unit, vc represents the communication speed, taken as 3×10 8 m/s.
Obtaining an initial phase deviation theta A,i+1 and a frequency deviation theta B,i+1 expression of a clock existing between a collecting unit and a collecting unit in the (i+1) th clock synchronization process by using a maximum likelihood estimation method:
step 3, the correction acquisition unit synchronizes the initial phase and the clock frequency in the data frame period at the broadcast time, specifically:
Adjusting the clock signal phase of the acquisition unit to be theta rev,i+1＝θinit,i+1+θA,i+1 by utilizing the obtained initial phase deviation theta A,i+1 of the clocks between the aggregation unit and the acquisition unit in the i+1th clock synchronization process, so as to ensure synchronization time synchronization, wherein theta init,i+1 is the initial phase of the acquisition unit in the i+1th clock synchronization process, and theta rev,i+1 is the adjusted phase of the acquisition unit in the i+1th clock synchronization process; and adjusting the clock frequency of the acquisition unit to be f rev,i+1＝finit,i+1+θB,i+1 by utilizing the obtained clock frequency deviation theta B,i+1 between the aggregation unit and the acquisition unit in the i+1th clock synchronization process, wherein f init,i+1 is the initial clock frequency of the acquisition unit in the i+1th clock synchronization process, and f rev,i+1 is the clock frequency of the acquisition unit after adjustment in the i+1th clock synchronization process. And finally, accurate time synchronization between the collecting unit and the collecting unit in the period of each broadcast time synchronization data frame is realized.
The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention. It will be readily understood by those skilled in the art that the foregoing description is merely illustrative of the presently preferred embodiments of the invention and is not intended to limit the invention to the particular forms disclosed, but to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims (4)

1.一种基于采集系统的配电网故障指示器精确时间同步方法，其特征在于，所述采集系统包括：采集单元、汇集单元；1. A distribution network fault indicator accurate time synchronization method based on a collection system, characterized in that the collection system comprises: a collection unit and a collection unit; 所述汇集单元与所述采集单元通过无线方式连接；The collection unit is connected to the acquisition unit wirelessly; 所述配电网故障指示器精确时间同步方法包括以下步骤：The distribution network fault indicator accurate time synchronization method comprises the following steps: 步骤1：所述采集单元用于实时采集配电线路实时电流，并无线传输至所述汇集单元；所述汇集单元根据配电线路实时电流计算得到配电线路电流的实时有效值；Step 1: The acquisition unit is used to collect the real-time current of the distribution line in real time and transmit it to the collection unit wirelessly; the collection unit calculates the real-time effective value of the distribution line current according to the real-time current of the distribution line; 步骤2：汇集单元计算采集单元的频偏变化率，根据采集单元的频偏变化率计算采集单元的频偏变化率时钟误差，根据采集单元的频偏变化率计算采集单元的同步时间数据帧发送最大间隔时间，根据配电线路电流的实时有效值、采集单元的同步时间数据帧发送最大间隔时间设定汇集单元的广播时间同步数据帧的周期；Step 2: The collection unit calculates the frequency deviation change rate of the collection unit, calculates the frequency deviation change rate clock error of the collection unit according to the frequency deviation change rate of the collection unit, calculates the maximum interval time for sending the synchronization time data frame of the collection unit according to the frequency deviation change rate of the collection unit, and sets the period of the broadcast time synchronization data frame of the collection unit according to the real-time effective value of the distribution line current and the maximum interval time for sending the synchronization time data frame of the collection unit; 步骤3：在广播时间同步数据帧的周期内，汇集单元向采集单元发送同步时间数据帧请求，采集单元接收到同步时间数据帧请求后，进一步发送同步时间数据帧应答至汇集单元；通过极大似然估计算法对发送同步时间数据帧请求和应答的时刻进行计算，得到采集单元在该广播时间同步数据帧周期内的相位偏差和频偏的估算，修正采集单元在该广播时间同步数据帧周期内的初始相位和时钟频率。Step 3: Within the period of the broadcast time synchronization data frame, the collection unit sends a synchronization time data frame request to the collection unit. After receiving the synchronization time data frame request, the collection unit further sends a synchronization time data frame response to the collection unit; the time of sending the synchronization time data frame request and response is calculated through the maximum likelihood estimation algorithm to obtain an estimate of the phase deviation and frequency deviation of the collection unit within the period of the broadcast time synchronization data frame, and correct the initial phase and clock frequency of the collection unit within the period of the broadcast time synchronization data frame. 2.根据权利要求1所述的基于采集系统的配电网故障指示器精确时间同步方法，其特征在于，2. The distribution network fault indicator accurate time synchronization method based on the acquisition system according to claim 1 is characterized in that: 步骤1所述配电线路实时电流为：The real-time current of the distribution line in step 1 is: X(1)，X(2)，X(3)，X(4)，……，X(NTs)X(1),X(2),X(3),X(4),…,X(N Ts ) 其中，X(k)表示配电线路k时刻电流，NTs表示采样时刻的数量，k∈[1,NTs]；Where X(k) represents the current of the distribution line at time k, N Ts represents the number of sampling times, k∈[1,N Ts ]; 步骤1中所述计算得到配电线路电流的实时有效值为：The real-time effective value of the distribution line current calculated in step 1 is: 式中，X(k)表示配电线路k时刻电流，X(eq)表示配电线路电流的实时有效值。Where X(k) represents the current of the distribution line at time k, and X(eq) represents the real-time effective value of the current of the distribution line. 3.根据权利要求1所述的基于采集系统的配电网故障指示器精确时间同步方法，其特征在于，步骤2中所述计算采集单元的频偏变化率为：3. The distribution network fault indicator accurate time synchronization method based on the acquisition system according to claim 1 is characterized in that the frequency deviation change rate of the acquisition unit calculated in step 2 is: 所述采集单元与所述汇集单元之间分别在ti、ti+1、ti+2进行时钟同步；The acquisition unit and the collection unit perform clock synchronization at ti , ti +1 , and ti +2 respectively; 则采集单元在Δti+1＝ti+1-ti时间段内由于频偏导致的时间偏移表示为：Then the time offset of the acquisition unit caused by the frequency deviation in the time period Δt i+1 =t i+1 -t i is expressed as: θ(ti+1)＝[T'(ti+1)-T'(ti)]-(ti+1-ti)θ(t i+1 )=[T'(t i+1 )-T'(t i )]-(t i+1 -t i ) 上式中，ti+1代表第i+1次时钟同步过程中汇集单元的时间，ti代表第i次时钟同步过程中汇集单元的时间，T'(ti+1)代表第i+1次时钟同步过程中采集单元的时间；T'(ti)分别代表第i次时钟同步过程中采集单元的时间；In the above formula, ti +1 represents the time of the collection unit during the i+1th clock synchronization process, ti represents the time of the collection unit during the i-th clock synchronization process, T'(ti +1 ) represents the time of the collection unit during the i+1th clock synchronization process; T'( ti ) represents the time of the collection unit during the i-th clock synchronization process; 采集单元在Δti+2＝ti+2-ti+1时间段内由于频偏导致的时间偏移表示为：The time offset of the acquisition unit caused by the frequency deviation in the time period of Δt i+2 =t i+2 -t i+1 is expressed as: θ(ti+2)＝[T'(ti+2)-T'(ti+1)]-(ti+2-ti+1)θ(t i+2 )=[T'(t i+2 )-T'(t i+1 )]-(t i+2 -t i+1 ) 上式中，ti+2代表第i+2次时钟同步过程中汇集单元的时间，ti+1代表第i+1次时钟同步过程中汇集单元的时间，T'(ti+2)代表第i+2次时钟同步过程中采集单元的时间，T'(ti+1)代表第i+1次时钟同步过程中采集单元的时间；In the above formula, ti +2 represents the time of the collection unit during the i+2th clock synchronization process, ti +1 represents the time of the collection unit during the i+1th clock synchronization process, T'(ti +2 ) represents the time of the collection unit during the i+2th clock synchronization process, and T'(ti +1 ) represents the time of the collection unit during the i+1th clock synchronization process; 步骤2所述采集单元的频偏变化率为：The frequency deviation change rate of the acquisition unit in step 2 is: 其中，γ表示步骤2所述采集单元的频偏变化率；Wherein, γ represents the frequency deviation change rate of the acquisition unit in step 2; 步骤2所述计算采集单元的频偏变化率时钟误差为：The frequency deviation change rate clock error of the acquisition unit calculated in step 2 is: 上式中，Top表示运行时间段，e表示时钟误差；In the above formula, T op represents the operation time period, and e represents the clock error; 步骤2所述计算采集单元的同步时间数据帧发送最大间隔时间为：The maximum interval time for sending the synchronization time data frame of the calculation collection unit in step 2 is: 上式中，Tint.max表示采集单元的同步时间数据帧发送最大间隔时间，EL.max代表精确故障定位对配电网故障指示器汇集单元与采集单元之间的时间同步误差的最低要求；In the above formula, Tint.max represents the maximum interval time of the synchronous time data frame sent by the acquisition unit, and E L.max represents the minimum requirement of the time synchronization error between the distribution network fault indicator collection unit and the acquisition unit for accurate fault location; 步骤2所述设定汇集单元的广播时间同步数据帧的周期为：The period of the broadcast time synchronization data frame of the aggregation unit is set as follows: 上式中，Tint.per表示汇集单元的广播时间同步数据帧的周期，X(eq)表示配电线路电流的实时有效值，IL.min表示故障指示器采集单元正常工作时对应的配电线路流过的最小电流，IL.max表示故障指示器采集单元正常工作时对应的配电线路流过的最大电流，Tint.min表示汇集单元广播时间同步数据帧的最小周期，X(eq)表示配电线路电流的实时有效值。In the above formula, Tint.per represents the period of the broadcast time synchronization data frame of the aggregation unit, X(eq) represents the real-time effective value of the distribution line current, IL.min represents the minimum current flowing through the corresponding distribution line when the fault indicator acquisition unit works normally, IL.max represents the maximum current flowing through the corresponding distribution line when the fault indicator acquisition unit works normally, Tint.min represents the minimum period of the broadcast time synchronization data frame of the aggregation unit, and X(eq) represents the real-time effective value of the distribution line current. 4.根据权利要求1所述的基于采集系统的配电网故障指示器精确时间同步方法，其特征在于，步骤3所述通过极大似然估计算法对发送同步时间数据帧请求和应答的时刻进行计算，得到采集单元在该广播时间同步数据帧周期内的相位偏差和频偏的估算具体为：4. The distribution network fault indicator accurate time synchronization method based on the acquisition system according to claim 1 is characterized in that the moment of sending the synchronization time data frame request and response is calculated by the maximum likelihood estimation algorithm in step 3, and the phase deviation and frequency deviation of the acquisition unit in the broadcast time synchronization data frame period are estimated specifically as follows: 根据汇集单元与采集单元之间的通信过程，得出时刻T1,i+1和T4,i+1的计算表达式：According to the communication process between the collection unit and the acquisition unit, the calculation expressions of time T 1,i+1 and T 4,i+1 are obtained: T1,i+1＝T2,i+1-d-xi+1+θB,i+1(T2,i+1-T4,i-d-xi+1)+θA,i+1 T 1,i+1 =T 2,i+1 -dx i+1 +θ B,i+1 (T 2,i+1 -T 4,i -dx i+1 )+θ A,i+1 ＝(1+θB,i+1)(T2,i+1-T4,i-d-xi+1)+θA,i+1+T4,i =(1+θ B,i+1 )(T 2,i+1 -T 4,i -dx i+1 )+θ A,i+1 +T 4,i T4,i+1＝T3,i+1+d+yi+1+θB,i+1(T3,i+1-T4,i+d+yi+1)+θA,i+1 T 4,i+1 =T 3,i+1 +d+y i+1 +θ B,i+1 (T 3,i+1 -T 4,i +d+y i+1 )+θ A,i+1 ＝(1+θB,i+1)(T3,i+1-T4,i+d+yi+1)+θA,i+1+T4,i =(1+θ B,i+1 )(T 3,i+1 -T 4,i +d+y i+1 )+θ A,i+1 +T 4,i 上式中，在第i+1次时钟同步过程中，采集单元应答同步时间数据帧至汇集单元的时刻为T1,i+1，汇集单元收到采集单元应答同步时间数据帧的时间为T2,i+1，并发送同步时间数据帧至采集单元，此时刻为T3,i+1；最后采集单元收到汇集单元发送回的同步时间数据帧的时刻为T4,i+1；同时，所提估算方法还需利用到第i次时钟同步过程中，采集单元收到汇集单元发送回的同步时间数据帧的时刻T4,i；d表示路径延时的确定部分；xi+1表示第i+1次时钟同步过程中采集单元发送同步数据帧至汇集单元时路径延时的不确定部分，其服从随机分布；θA,i+1表示第i+1次时钟同步过程中汇集单元与采集单元之间存在的时钟初始相位偏差；θB,i+1表示第i+1次时钟同步过程中汇集单元与采集单元之间的频偏，θB,i+1(T1,i+1-T4,i+d+xi+1)表示由于频偏导致的时钟偏差；yi+1表示第i+1次时钟同步过程中汇集单元发送同步数据帧至采集单元时路径延时的不确定部分，其也服从随机分布；In the above formula, during the i+1th clock synchronization process, the time when the collection unit responds to the synchronization time data frame to the collection unit is T 1,i+1 , the time when the collection unit receives the synchronization time data frame from the collection unit is T 2,i+1 , and sends the synchronization time data frame to the collection unit, this time is T 3,i+1 ; finally, the time when the collection unit receives the synchronization time data frame sent back by the collection unit is T 4,i+1 ; at the same time, the proposed estimation method also needs to use the time T 4,i when the collection unit receives the synchronization time data frame sent back by the collection unit during the i+1th clock synchronization; d represents the determined part of the path delay; x i+1 represents the uncertain part of the path delay when the collection unit sends the synchronization data frame to the collection unit during the i+1th clock synchronization, which obeys random distribution; θ A,i+1 represents the initial clock phase deviation between the collection unit and the collection unit during the i+1th clock synchronization; θ B,i+1 represents the frequency deviation between the collection unit and the collection unit during the i+1th clock synchronization, θ B,i+1 (T 1,i+1 -T 4,i +d+xi +1 ) represents the clock deviation caused by frequency deviation; yi +1 represents the uncertain part of the path delay when the aggregation unit sends the synchronization data frame to the acquisition unit during the i+1th clock synchronization process, which also obeys random distribution; 令S1＝T1,i+1-T4,i；S2＝T2,i+1-T4,i；S3＝T3,i+1-T4,i；S4＝T4,i+1-T4,i；利用极大似然估计法，得到第i+1次时钟同步过程中汇集单元与采集单元之间存在的时钟初始相位偏差θA,i+1以及频偏θB,i+1表达式：Let S 1 =T 1,i+1 -T 4,i ; S 2 =T 2,i+1 -T 4,i ; S 3 =T 3,i+1 -T 4,i ; S 4 =T 4,i+1 -T 4,i ; and use the maximum likelihood estimation method to obtain the expressions of the clock initial phase deviation θ A,i+1 and frequency deviation θ B,i+1 between the aggregation unit and the acquisition unit in the i+1th clock synchronization process: 上式中d表示路径延时的确定部分，计算公式为d＝Ldis/vc，Ldis表示汇集单元与采集单元之间的距离，vc表示通信速度，取为3×108m/s；In the above formula, d represents the determining part of the path delay, and the calculation formula is d = L dis /vc, L dis represents the distance between the collection unit and the collection unit, and vc represents the communication speed, which is taken as 3×10 8 m/s; 步骤3所述修正采集单元在该广播时间同步数据帧周期内的初始相位和时钟频率，具体为：Step 3, in which the initial phase and clock frequency of the acquisition unit are corrected within the broadcast time synchronization data frame period, is specifically: 利用得到的第i+1次时钟同步过程中汇集单元与采集单元之间时钟初始相位偏差θA,i+1，调整采集单元的时钟信号相位为θrev,i+1＝θinit,i+1+θA,i+1，保证同步对时，其中θinit,i+1为采集单元在第i+1次时钟同步过程中的初始相位，θrev,i+1为采集单元在第i+1次时钟同步过程中调整后的相位；利用得到的第i+1次时钟同步过程中汇集单元与采集单元之间时钟频偏θB,i+1，调整采集单元的时钟频率为frev,i+1＝finit,i+1+θB,i+1，其中finit,i+1为采集单元在第i+1次时钟同步过程中的初始时钟频率，frev,i+1为采集单元在第i+1次时钟同步过程中调整后的时钟频率；最终实现每个广播时间同步数据帧的周期内汇集单元与采集单元之间的精确时间同步。By using the obtained initial clock phase deviation θ A,i+1 between the collection unit and the collection unit during the i+1th clock synchronization process, the clock signal phase of the collection unit is adjusted to θ rev,i+1 =θ init,i+1 +θ A,i+1 to ensure synchronization, wherein θ init,i+1 is the initial phase of the collection unit during the i+1th clock synchronization process, and θ rev,i+1 is the adjusted phase of the collection unit during the i+1th clock synchronization process; by using the obtained clock frequency deviation θ B,i+1 between the collection unit and the collection unit during the i+1th clock synchronization process, the clock frequency of the collection unit is adjusted to f rev,i+1 = finit,i+1 +θ B,i+1 , whereinfinit,i+1 is the initial clock frequency of the collection unit during the i+1th clock synchronization process, and f rev,i+1 is the adjusted clock frequency of the collection unit during the i+1th clock synchronization process; finally, accurate time synchronization between the collection unit and the collection unit within the period of each broadcast time synchronization data frame is achieved.
CN202210019806.XA 2022-01-10 2022-01-10 A method for accurate time synchronization of distribution network fault indicators based on acquisition system Active CN114487702B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210019806.XA CN114487702B (en) 2022-01-10 2022-01-10 A method for accurate time synchronization of distribution network fault indicators based on acquisition system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210019806.XA CN114487702B (en) 2022-01-10 2022-01-10 A method for accurate time synchronization of distribution network fault indicators based on acquisition system

Publications (2)

Publication Number Publication Date
CN114487702A CN114487702A (en) 2022-05-13
CN114487702B true CN114487702B (en) 2025-02-14

Family

ID=81509607

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210019806.XA Active CN114487702B (en) 2022-01-10 2022-01-10 A method for accurate time synchronization of distribution network fault indicators based on acquisition system

Country Status (1)

Country Link
CN (1) CN114487702B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117407572B (en) * 2023-12-15 2024-03-15 国网浙江省电力有限公司绍兴供电公司 Fault information processing method and system for distribution network emergency integrated command

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1780276A (en) * 2004-11-25 2006-05-31 都科摩（北京）通信技术研究中心有限公司 Combined time synchronizing and frequency bias evaluation and evaluating device for orthogonal frequency division duplex system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI407719B (en) * 2007-07-26 2013-09-01 Univ Nat Chiao Tung A symbol time synchronization method for ofdm systems

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1780276A (en) * 2004-11-25 2006-05-31 都科摩（北京）通信技术研究中心有限公司 Combined time synchronizing and frequency bias evaluation and evaluating device for orthogonal frequency division duplex system

Also Published As

Publication number Publication date
CN114487702A (en) 2022-05-13

Similar Documents

Publication Publication Date Title
CN111711948B (en) Method and system for acquiring high-precision time from 5G base station through air interface
CN201127028Y (en) Time Synchronization System for Transferring Time Through Synchronous Digital Hierarchy Optical Communication Network
CN114487702B (en) A method for accurate time synchronization of distribution network fault indicators based on acquisition system
CN202889361U (en) Internet of Things terminal and Internet of Things time service system
CN113037415A (en) TSN (time delay network) clock synchronization method, system and equipment based on vehicle-mounted Ethernet transmission
CN111565084A (en) A satellite timing system and method based on frequency estimation
CN203313199U (en) Intelligent electronic device IEEE C37.238 time synchronization system
CN104410481B (en) A kind of setting means based on NTP networks and pair when system
CN101217330A (en) A method and device for time synchronization correction
CN101534002A (en) Data synchronization method for ET-connected optical-fiber differential protection devices
CN204631463U (en) A GPS Clock Synchronization System for Radiation Source Monitoring and Positioning
CN113315546A (en) Time synchronization method of low-voltage distribution room acquisition system based on HPLC carrier
CN105142210B (en) A kind of real-time clock synchronous calibration method and sensor for wireless sense network
CN101771487A (en) Equipment for network time service precision detection and detection method using the detection equipment
CN104079401B (en) A kind of short-period real-time communication system of high accuracy based on chain EPA network
CN108235427A (en) A kind of method for measuring Tof and Toda
WO2022262019A1 (en) 5g communication-based alternating current/direct current electric power transmission line traveling wave fault distance-measuring method and system
WO2021008532A1 (en) Active antenna unit delay alignment method and apparatus and active antenna unit
CN114205045B (en) TTE network clock calibration method and system
WO2012058986A1 (en) Communication system and method for transmitting clock signal
CN101236216B (en) Electrical power system metric data time difference compensation state estimation method
CN114374461A (en) Accurate time synchronization system for low-voltage transformer area electric meter
CN107231206A (en) A kind of satellite navigation time service is kept time the solution in clock system
CN116506802A (en) Underwater node time synchronization method for distributed acoustic measurement of ocean current field
CN103124212A (en) Numerical control system field bus time synchronization method and device based on Bayes principle

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant