Terminal timing method for low voltage substation area based on maximum matching of downsampled feature sequences

Abstract

The present invention discloses a low-voltage area terminal timing method based on maximum matching of down-sampling feature sequences, including: the user-side measurement terminal extracts significant voltage change events, and the user-side measurement terminal uploads the time sequence of significant voltage change events and the state sequence of significant voltage change events to the edge terminal; the edge terminal calculates the clock deviation between any two user-side measurement terminals by the down-sampling maximum sequence matching method; the edge terminal selects a user-side measurement terminal as a reference, calculates the clock deviation between other user-side measurement terminals and it, and sends it to other user-side measurement terminals; the user-side measurement terminal performs time offset when uploading cross-section data based on the received clock deviation, so as to realize accurate timing of low-voltage area terminals. The present invention does not rely on GPS / Beidou synchronous timing, the terminal equipment in the area asynchronously collects feature sequences, and the edge equipment in the area aligns the feature sequences of each terminal, and finally realizes clock synchronization between various types of equipment.

Description

Technical Field

[0001] The present invention relates to the field of power distribution technology, and in particular to a low-voltage station terminal timing method based on maximum matching of down-sampling feature sequences. Background Art

[0002] With the deepening of the digital construction of low-voltage distribution networks, more and more intelligent measurement devices are connected to the intelligent distribution network, and clock synchronization between measurement devices has become an important research topic. The uPMU device equipped with GPS / Beidou chips is a high-precision power measurement device that can collect phase information such as current and voltage of the power system with a microsecond sampling cycle, and calculate the power, phase, power angle and other information of the measurement point. It can synchronize each state quantity to the same time section to achieve real-time synchronous monitoring of the power system operation information, but the cost is high and it is difficult to implement in practical applications. Summary of the invention

[0003] Technical purpose: In response to the defects in the prior art, the present invention discloses a low-voltage substation terminal timing method based on maximum matching of down-sampling feature sequences. It does not rely on GPS / Beidou synchronous timing. Terminal devices in the substation asynchronously collect feature sequences, and the edge devices in the substation align the feature sequences of each terminal, ultimately achieving clock synchronization between various devices.

[0004] Technical solution: In order to achieve the above technical objectives, the present invention adopts the following technical solution.

[0005] A low voltage area terminal time synchronization method based on maximum matching of down-sampling feature sequences, the method comprising:

[0006] The user-side measurement terminal extracts a significant voltage change event, wherein the voltage change of the user-side measurement terminal is determined according to a preset threshold to determine whether it belongs to a significant voltage change event; the user-side measurement terminal is a low-voltage station terminal;

[0007] The user-side measurement-side terminal uploads the time sequence of significant voltage change events and the state sequence of significant voltage change events to the edge terminal;

[0008] The edge terminal calculates the clock deviation between any two user-side measurement terminals through the downsampling maximum sequence matching method;

[0009] The edge terminal selects a user-side measurement terminal as a reference, calculates the clock deviations of other user-side measurement terminals and the reference, and sends the result to other user-side measurement terminals.

[0010] The user-side measurement terminal performs time offset when uploading section data based on the received clock deviation, thereby achieving accurate time synchronization of the low-voltage substation terminal.

[0011] Preferably, the significant voltage change event includes time information; the user-side measurement terminal continuously calculates the effective value of its own voltage for several cycles under its own clock. , calculate the difference of the effective value of the frequency voltage at adjacent times to get the time The value of the frequency voltage change , filter out the number of days that exceed the preset threshold The time of the user-side measurement terminal The value of the frequency voltage change The absolute value of the voltage change event is marked as a significant voltage change event, and the time of the significant voltage change event is recorded synchronously. .

[0012] Preferably, the voltage change value of each significant voltage change event is The positive and negative relationship of the voltage change state is obtained , voltage change state The calculation formula is:

[0013] ,

[0014] in, When , it indicates that the voltage increases; , it indicates that the voltage decreases.

[0015] Preferably, the edge terminal calculates the clock deviation between any two user-side measurement terminals by using a downsampling maximum sequence matching method, including the following steps:

[0016] The time series of significant voltage change events sent by each user-side measurement terminal , generate downsampled time series ;

[0017] The time series after fusion downsampling for each user-side measurement terminal and state sequence , construct a comparison sequence ; Compare sequences Elements in The calculation formula is:

[0018] ,

[0019] in, is the moment of significant voltage change event, is the voltage change state;

[0020] Measurement terminal on the user side Comparison sequence Apply offset Then get the offset sequence , offset sequence With the user-side measurement terminal Comparison sequence Take the intersection of the elements and record the maximum number of intersections, that is, the offset corresponding to the maximum number of common elements ;

[0021] According to the maximum offset Calculate the user-side measurement terminal , User-side measurement terminal of clock error.

[0022] Preferably, the downsampled time series The calculation formula is:

[0023] ,

[0024] in, Indicates that the input value is rounded down. is the time series after downsampling The elements in , is the time series of significant voltage change events The elements in .

[0025] Preferably, the maximum offset corresponding to the maximum number of intersections is The calculation process includes:

[0026] ,

[0027] in, is the offset; Indicated in and Find common elements in the output and use them to output the common elements in the offset sequence The index number in , common elements in the comparison sequence The index number in , the number of common elements .

[0028] Preferably, according to the maximum offset Corresponding , Locating the user-side measurement terminal Comparison sequence And user-side measurement terminal Comparison sequence The corresponding common elements in the user side measurement terminal , User-side measurement terminal Time series of significant voltage change events Subtract the time from the previous one and take the average value as the clock error.

[0029] Preferably, the user-side measurement terminal , User-side measurement terminal The clock error The calculation formula includes:

[0030] ,

[0031] in, Measuring terminals on the user side for common elements Time series of significant voltage change events The moment in Measuring terminals on the user side for common elements Time series of significant voltage change events The moment in Measuring terminals on the user side for common elements , User-side measurement terminal Time series of significant voltage change events The time difference in Indicates taking the mean value.

[0032] Beneficial effects:

[0033] 1. Some existing methods for clock synchronization in low-voltage areas require adding hardware modules other than measurement and communication modules to the user-side measurement terminal through micro-synchronous vector measurement unit μpmu equipment and GPS timing. This method does not require the installation of additional equipment and does not rely on GPS / Beidou synchronous timing. The terminal equipment in the area asynchronously collects feature sequences, and the edge equipment in the area aligns the feature sequences of each terminal, ultimately achieving clock synchronization among various devices.

[0034] 2. Some existing low-voltage substation clock synchronization methods perform clock synchronization by sending synchronization instructions from the edge side terminal to the user side terminal. However, the synchronization effect is greatly affected by the communication quality of the substation, and it is impossible to accurately guarantee the clock alignment of the user side measurement terminal. The present invention is based on the clock synchronization technology of matching the characteristic sequence collected by the measurement equipment in the substation. The terminal equipment in the substation asynchronously collects the characteristic sequence, and the edge equipment of the substation aligns the characteristic sequence of each terminal, and sends the synchronization information in the form of the absolute value of the clock deviation. It has low requirements on the real-time communication quality and still has a good synchronization effect in the data complex substation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] As attached Figure 1 As shown, a low-voltage area terminal timing method based on maximum matching of down-sampling feature sequences in this embodiment uses the principle of voltage similarity within the same area to extract events with significant voltage changes on the user side and form a sequence to upload to the edge side, and the edge side performs clock alignment on all user-side uplink sequences; the following steps are included:

[0038] Step 1: The user-side measurement terminal extracts a significant voltage change event, wherein it is determined whether the voltage change of the user-side measurement terminal belongs to a significant voltage change event according to a preset threshold; the significant voltage change event includes time information and state information; the user-side measurement terminal is a low-voltage station terminal;

[0039] The user-side measurement terminal continuously calculates the effective value of its own voltage for several cycles under its own clock. In some embodiments of the present invention, the cyclic voltage is sampled at a frequency of 20 ms / point to obtain The effective value of the frequency voltage , calculate the difference of the effective value of the frequency voltage at adjacent times to get the time The value of the frequency voltage change ,time The value of the frequency voltage change The calculation formula is:

[0040] ,

[0041] in, For the moment The effective value of the frequency voltage;

[0042] Filter out the number of days that exceed the preset threshold The time of the user-side measurement terminal The value of the frequency voltage change The absolute value of the voltage change event is marked as a significant voltage change event, and the time of the significant voltage change event is recorded synchronously. ,time Expressed in seconds, the value range is 0-86400, the minimum resolution is 0.02, and the preset threshold is The selection is made according to the actual situation. In some embodiments of the present invention, the preset threshold The value range is 3V-5V; in addition, according to the cycle voltage change value of each significant voltage change event The positive and negative relationship of the voltage change state is obtained , voltage change state The calculation formula is:

[0043] ,

[0044] in, When , it indicates that the voltage increases; , it indicates that the voltage decreases.

[0045] Step 2: The user-side measurement terminal uploads the time series of significant voltage change events and the state series of significant voltage change events to the edge terminal; each user-side measurement terminal sends a collection of significant voltage change events. , To the edge terminal, where , , which are the time series and state series of significant voltage change events respectively.

[0046] Step 3: The edge terminal calculates the clock deviation between any two user-side measurement terminals by using the downsampling maximum sequence matching method;

[0047] According to the event set obtained in step 2, the down-sampling maximum sequence matching operation is performed for any two user-side measurement terminals. The clock deviation is calculated as follows:

[0048] Step 3.1: Generate a downsampled time series for the time series of significant voltage change events sent by each user-side measurement terminal In some embodiments of the present invention, the granularity of the time series is downsampled from 0.02S to 1S to obtain the downsampled time series ;

[0049] Among them, the time series after downsampling The calculation formula is:

[0050] ,

[0051] in, It means to round down the input value, that is, to take the largest integer not greater than the input value, such as floor(2.04)=2.

[0052] Step 3.2: Fusion downsampled time series of each user-side measurement terminal and state sequence , construct a comparison sequence ; Compare sequences Elements in The calculation formula is:

[0053] ,

[0054] in, is the moment of significant voltage change event, is the voltage change state;

[0055] Step 3.3: Measure the terminal on the user side Comparison sequence Apply offset Then get the offset sequence , offset sequence With the user-side measurement terminal Comparison sequence Take the intersection of the elements and record the maximum number of intersections, that is, the offset corresponding to the maximum number of common elements ; The calculation process includes:

[0056] ,

[0057] in, Indicated in and Find common elements in the output and use them to output the common elements in the offset sequence The index number in , common elements in the comparison sequence The index number in , the number of common elements .For example, ;Offset The value is an integer between -900 and 900, that is, a deviation of plus or minus 15 minutes. The number of common elements output when taking different values Also different, according to the largest number of common elements Find the corresponding maximum offset .

[0058] Step 3.3: Maximum offset obtained from step 3.2 Calculate the user-side measurement terminal , User-side measurement terminal The clock error of

[0059] According to the maximum offset Corresponding , Locating the user-side measurement terminal Comparison sequence And user-side measurement terminal Comparison sequence The corresponding common elements in the user side measurement terminal , User-side measurement terminal Time series of significant voltage change events The time is subtracted from the time, and the average value is taken as the accurate clock error. The average value operation is used to deal with the slight differences in the various differences caused by the progressive error of the device's own clock during the day.

[0060] User-side measurement terminal , User-side measurement terminal The clock error The calculation formula includes:

[0061] ,

[0062] in, Measuring terminals on the user side for common elements Time series of significant voltage change events The moment in Measuring terminals on the user side for common elements Time series of significant voltage change events The moment in Measuring terminals on the user side for common elements , User-side measurement terminal Time series of significant voltage change events The time difference in Indicates taking the mean value.

[0063] Step 4: The edge terminal selects a user-side measurement terminal as a reference, calculates the clock deviations of other user-side measurement terminals and the reference, and sends the calculation results to other user-side measurement terminals.

[0064] The edge terminal selects a user-side measurement terminal as the reference, and obtains the clock deviations between other user-side measurement terminals and the edge terminal based on the calculation in step 3. For example, if the fixed terminal 1 is the reference, the clock deviation is 0, and the clock deviations of other terminals are , send deviation parameters to other terminals.

[0065] Step 5: The user-side measurement terminal performs time offset when uploading section data based on the received clock deviation to achieve accurate time synchronization of the low-voltage substation terminal.

[0066] Based on the clock deviation parameters issued in step 4, the user-side terminal i uploads section data, such as when the 1, 15, and 60-minute electrical quantity is frozen, The data is frozen in seconds and uploaded.

[0067] In this embodiment, the method is basically simulated and verified, and the specific situation is as follows:

[0068] In a certain residential area in a certain city in a certain province, a clock synchronization experiment was conducted on 4 user-side measurement terminals. During the experiment, a handheld terminal was used to synchronize the clocks of terminals 1, 2, 3, and 4 respectively through 485 communication. The deviations from the standard clock were set to 0s, +1.2s, -1.8s, and +45.1s, respectively. The experimental verification time was 1 day.

[0069] The experimental results are shown in Table 1, which is a clock deviation verification table:

[0070]

[0071] It can be seen from Table 1 that the clock deviation identified by this method is basically consistent with the set value, and the predetermined clock synchronization effect is achieved.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low voltage area terminal time synchronization method based on maximum matching of down-sampling feature sequences, characterized in that: The method comprises: The user-side measurement terminal extracts a significant voltage change event, wherein the voltage change of the user-side measurement terminal is determined according to a preset threshold to determine whether it belongs to a significant voltage change event; the user-side measurement terminal is a low-voltage station terminal; The user-side measurement-side terminal uploads the time sequence of the significant voltage change event and the state sequence of the significant voltage change event to the edge terminal; The edge terminal calculates the clock deviation between any two user-side measurement terminals by using the downsampling maximum sequence matching method, including the following steps: The time series of significant voltage change events sent by each user-side measurement terminal , generate downsampled time series ; The time series after fusion downsampling for each user-side measurement terminal and state sequence , construct a comparison sequence ; Compare sequences Elements in The calculation formula is: ， in, is the moment of significant voltage change event, is the voltage change state; When , it indicates that the voltage increases; When , it indicates that the voltage decreases; Measurement terminal on the user side Comparison sequence Apply offset Then get the offset sequence , offset sequence With the user-side measurement terminal Comparison sequence Take the intersection of the elements and record the maximum number of intersections, that is, the offset corresponding to the maximum number of common elements ; According to the maximum offset Calculate the user-side measurement terminal , User-side measurement terminal The clock error of The edge terminal selects a user-side measurement terminal as a reference, calculates the clock deviations of other user-side measurement terminals and the reference, and sends the result to other user-side measurement terminals. The user-side measurement terminal performs time offset when uploading section data based on the received clock deviation, thereby achieving accurate time synchronization of the low-voltage substation terminal.

2. According to claim 1, a low-voltage area terminal timing method based on maximum matching of down-sampling feature sequences is characterized by: Significant voltage change events include time information; the user-side measurement terminal continuously calculates the effective value of its own voltage for several cycles under its own clock , calculate the difference of the effective value of the frequency voltage at adjacent times to get the time The value of the frequency voltage change , filter out the number of days that exceed the preset threshold The time of the user-side measurement terminal The value of the frequency voltage change The absolute value of the voltage change event is marked as a significant voltage change event, and the time of the significant voltage change event is recorded synchronously. .

3. According to claim 2, a low-voltage area terminal timing method based on maximum matching of down-sampling feature sequences is characterized in that: The significant voltage change event also includes status information; according to the cycle voltage change value of each significant voltage change event The positive and negative relationship of the voltage change state is obtained , voltage change state The calculation formula is: ， in, When , it indicates that the voltage increases; , it indicates that the voltage decreases.

4. According to claim 1, a low-voltage area terminal time synchronization method based on maximum matching of down-sampling feature sequences is characterized in that: Downsampled time series The calculation formula is: ， in, Indicates that the input value is rounded down. is the time series after downsampling The elements in , is the time series of significant voltage change events The elements in .

5. According to claim 1, a low voltage area terminal time synchronization method based on maximum matching of down-sampling feature sequences is characterized by: The maximum offset corresponding to the maximum number of intersections The calculation process includes: ， in, is the offset; Indicated in and Find common elements in the output and use them to output the common elements in the offset sequence The index number in , common elements in the comparison sequence The index number in , the number of common elements .

6. A low voltage area terminal time synchronization method based on maximum matching of down-sampling feature sequences according to claim 5, characterized in that: According to the maximum offset Corresponding , Locate the user-side measurement terminal Comparison sequence And user-side measurement terminal Comparison sequence The corresponding common elements in the user side measurement terminal , User-side measurement terminal Time series of significant voltage change events Subtract the time from the previous one and take the average value as the clock error.

7. The method for synchronizing low-voltage area terminals based on maximum matching of down-sampled feature sequences according to claim 6 is characterized in that: User-side measurement terminal , User-side measurement terminal The clock error The calculation formula include: ， in, Measuring terminals on the user side for common elements Time series of significant voltage change events The moment in Measuring terminals on the user side for common elements Time series of significant voltage change events The moment in Measuring terminals on the user side for common elements , User-side measurement terminal Time series of significant voltage change events The time difference in Indicates taking the mean value.

Images