A method and system for data synchronization of differential protection for power distribution lines

Abstract

This invention discloses a method and system for synchronizing differential protection data on power distribution lines, belonging to the field of power distribution differential protection technology. The method includes: determining the current time as the data transmission time of the M / N side protection device; packaging the time-stamped differential protection data into a package; caching the packaged data locally, and sending the packaged data from the M-side protection device to the N-side protection device, and sending the packaged data from the N-side protection device to the M-side protection device; when the M / N side protection device receives the packaged data, extracting the time stamp from the packaged data, and matching the extracted time stamp with the time stamp of the locally cached packaged data. This invention provides a method and system for synchronizing differential protection data on power distribution lines, achieving synchronization of differential protection data sampled by protection devices on both sides of the protected power distribution line through time stamp matching.

Description

Technical Field

[0001] This invention relates to the field of power distribution differential protection technology, and more specifically, to a method and system for data synchronization of differential protection for power distribution lines. Background Technology

[0002] The basic principle of differential current protection (or differential protection for short) is Kirchhoff's Current Law (KCL), which states that at any node, at any given moment, the sum of the currents flowing into the node equals the sum of the currents flowing out of the node. In differential protection, the protected line can be abstracted as a node. At any given moment, the current flowing into the line equals the current flowing out of the line. If this condition is not met, a fault has occurred on that line at that moment.

[0003] As mentioned above, differential protection identifies faults inside and outside the protection zone by exchanging current data at both ends of the line in real time. When applied to distribution networks, the first challenge is addressing the communication channel issue. The key technology lies in achieving a lower and more stable communication channel delay between the protection devices on both sides of the protected line. Currently, the main communication methods for differential protection in distribution networks are carrier communication, fiber optic communication, and 5G wireless communication.

[0004] Carrier communication equipment is simple and inexpensive, but its anti-interference capability is poor. With the widespread access of distributed power sources to distribution networks in recent years, the distribution network and line environment have become more complex, and the characteristics of line faults have become more diversified. The reliability of carrier communication does not meet the requirements of differential protection applications.

[0005] Fiber optic communication offers high transmission stability and relatively low latency. However, due to the large number and wide distribution network points, large-scale fiber optic deployment faces numerous challenges, including high costs, long construction periods, and difficulties, which have become the main bottleneck restricting the promotion and application of differential protection in distribution networks.

[0006] 5G is the fifth generation of mobile network communication technology, offering higher speeds, larger capacity, and lower latency compared to 4G. As 5G communication technology matures and becomes commercially available, its applications in vertical business sectors are deepening, with distributed protection and control of smart power distribution networks being one of the most promising application areas.

[0007] As can be seen from the first paragraph, differential protection devices need to adopt a reasonable synchronization mechanism to ensure the consistency of sampling time and data transmission time. Currently, the timing methods applied to distribution network differential protection mainly include the fault timing method, the 5G communication timing method, and the GPS / BD-based satellite timing method.

[0008] The principle of the fault-time method is to approximate the moment of current change detected by the protection device as the actual fault time, and then synchronously start sampling and transmit data. However, the self-synchronization algorithm has its own errors, especially when the line contains distributed generation (DG). There is a certain phase difference between the two power sources and the equivalent impedance to the fault point is different. The fault currents on both sides themselves have a certain angle difference, which is not conducive to the differential protection exerting its own advantages.

[0009] The 5G communication time synchronization method, through the configuration of 5G base stations, enables 5G information to carry absolute time information. Therefore, this time information can be used to achieve synchronized sampling by protection devices on both sides. 5G time synchronization actually consists of two parts: time synchronization between 5G base stations and time synchronization between base stations and 5G terminals. Time synchronization between 5G base stations is achieved by the time server in the 5G network receiving and parsing time information from the satellite, and then transmitting PTP messages with high-precision time information through the 5G time synchronization bearer network to synchronize the time of each base station. This technology can be provided by telecom operators. Currently, various operators in my country can achieve an air interface time deviation of less than 1.5µs between base stations, reaching a relatively high level. After the 5G terminal completes time synchronization, it can output this absolute time information in B-code form for use by the protection device. However, this method is limited by the cooperation of operators. Although it can guarantee the time deviation between base stations, its accuracy will inevitably decrease for applications across base stations and across routes. There are few application examples for distribution networks with many nodes, and the application effect cannot be guaranteed. Summary of the Invention

[0010] To address the above problems, this invention proposes a method for synchronizing differential protection data in power distribution lines, comprising:

[0011] The protection device on the M / N side of the protected power distribution line generates millisecond pulses and counts them. If the count output value T of the millisecond pulses is... c The data transmission period T for the M / N side protection device s If the remainder is zero, then the current time is determined to be the data transmission time of the M / N side protection device;

[0012] Latch the count output value T c The count output value T c As a time stamp, it is added to the differential protection data of the M / N side protection device at the current moment, and the differential protection data with the time stamp is packaged to obtain the packaged data;

[0013] The packaged data is cached locally, and the packaged data of the M-side protection device is sent to the N-side protection device, and the packaged data of the N-side protection device is sent to the M-side protection device.

[0014] When the M / N side protection device receives the packaged data, it extracts the timestamp from the packaged data and matches the timestamp extracted from the packaged data with the timestamp of the locally cached packaged data. If the match is consistent, the differential protection data synchronization is completed.

[0015] Optionally, after a match is found, differential protection algorithm processing is performed on the packaged data locally cached by the M-side protection device and the packaged data received from the N-side protection device, and differential protection algorithm processing is performed on the packaged data locally cached by the N-side protection device and the packaged data received from the M-side protection device.

[0016] Optionally, if a match fails, the received packaged data is discarded, and the number of failed matches is determined. If the number of failed matches exceeds a set value N, the data is further processed. s If the channel delay is abnormal, the differential protection will be blocked. This will occur when N consecutive [times / times / conditions] are [affected / interrupted]. s After a matching is successful, the interlocking differential protection is deactivated.

[0017] Optionally, the M / N side protection device includes a high-precision crystal oscillator and a counter, with the high-precision crystal oscillator serving as a millisecond timer;

[0018] The millisecond timer generates millisecond pulses by cyclically resetting its timer value to zero.

[0019] The counter increments by 1 when the millisecond timer generates a millisecond pulse.

[0020] Optionally, the method also includes synchronizing the millisecond timer and counter, including:

[0021] If the millisecond timer and counter detect a time synchronization signal, the millisecond timer and counter are reset and restarted to synchronize with the time synchronization signal.

[0022] If the millisecond timer and counter do not detect the time synchronization signal, determine whether the time synchronization signal has timed out. If the time synchronization has timed out, determine the number of timeouts. If the number of timeouts is less than a set value N... a Then, the millisecond timer and counter are reset. If the number of timeouts is greater than or equal to the set value N, the timeout will be reset. a If the timing is abnormal, the differential protection will be locked out. This will occur if N consecutive cycles occur. a When the calibration signal arrives, the differential protection is deactivated.

[0023] Optionally, the counter's full value is 1000 + Δn, and the count output value T... c If the value is ≥1000+Δn, the time synchronization will time out.

[0024] Where Δn is the allowable timeout for a single instance, Δn×N a ≤Tpmax T pmax The maximum clock difference allowed for differential protection.

[0025] Optionally, the method also includes:

[0026] Establish communication between the protection devices on the M and N sides, and minimize communication delay;

[0027] Synchronize the time for the protection devices on the M and N sides.

[0028] Optionally, the method also includes:

[0029] The data transmission cycle T of the control M and N side protection devices s Less than the maximum communication delay of the protection devices on the M and N sides.

[0030] This invention also proposes a system for data synchronization of differential protection in power distribution lines, comprising:

[0031] The initial unit is used to generate millisecond pulses through the protection device on the M / N side of the protected distribution line, and to count the millisecond pulses. If the count output value T of the millisecond pulses is... c The data transmission period T for the M / N side protection device s If the remainder is zero, then the current time is determined to be the data transmission time of the M / N side protection device;

[0032] The data packaging unit is used to latch the counting output value T. c The count output value T c As a time stamp, it is added to the differential protection data of the M / N side protection device at the current moment, and the differential protection data with the time stamp is packaged to obtain the packaged data;

[0033] The data sending unit is used to cache the packaged data locally, send the packaged data of the M-side protection device to the N-side protection device, and send the packaged data of the N-side protection device to the M-side protection device.

[0034] The data synchronization unit is used to extract the timestamp from the packaged data after the protection device on the M / N side receives the packaged data, and match the timestamp extracted from the packaged data with the timestamp of the locally cached packaged data. If the match is consistent, the differential protection data synchronization is completed.

[0035] Optionally, after a match is found, differential protection algorithm processing is performed on the packaged data locally cached by the M-side protection device and the packaged data received from the N-side protection device, and differential protection algorithm processing is performed on the packaged data locally cached by the N-side protection device and the packaged data received from the M-side protection device.

[0036] Optionally, if a match fails, the received packaged data is discarded, and the number of failed matches is determined. If the number of failed matches exceeds a set value N, the data is further processed. s If the channel delay is abnormal, the differential protection will be blocked. This will occur when N consecutive [times / times / conditions] are [affected / interrupted]. s After a matching is successful, the interlocking differential protection is deactivated.

[0037] Optionally, the M / N side protection device includes a high-precision crystal oscillator and a counter, with the high-precision crystal oscillator serving as a millisecond timer;

[0038] The millisecond timer generates millisecond pulses by cyclically resetting its timer value to zero.

[0039] The counter increments by 1 when the millisecond timer generates a millisecond pulse.

[0040] Optionally, the system also includes a time synchronization unit for synchronizing the millisecond timer and counter, including:

[0041] If the millisecond timer and counter detect a time synchronization signal, the millisecond timer and counter are reset and restarted to synchronize with the time synchronization signal.

[0042] If the millisecond timer and counter do not detect the time synchronization signal, determine whether the time synchronization signal has timed out. If the time synchronization has timed out, determine the number of timeouts. If the number of timeouts is less than a set value N... a Then, the millisecond timer and counter are reset. If the number of timeouts is greater than or equal to the set value N, the timeout will be reset. a If the timing is abnormal, the differential protection will be locked out. This will occur if N consecutive cycles occur. a When the calibration signal arrives, the differential protection is deactivated.

[0043] Optionally, the counter's full value is 1000 + Δn, and the count output value T... c If the value is ≥1000+Δn, the time synchronization will time out.

[0044] Where Δn is the allowable timeout for a single instance, Δn×N a ≤T pmax T pmax The maximum clock difference allowed for differential protection.

[0045] Optionally, the initial unit is also used for:

[0046] Establish communication between the protection devices on the M and N sides, and minimize communication delay;

[0047] Synchronize the time for the protection devices on the M and N sides.

[0048] Optionally, the initial unit is also used for:

[0049] The data transmission cycle T of the control M and N side protection devices s Less than the maximum communication delay of the protection devices on the M and N sides.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] This invention provides a method and system for synchronizing differential protection data for power distribution lines. By matching time stamps, the differential protection data sampled by the protection devices on both sides of the protected power distribution line is synchronized. Attached Figure Description

[0052] Figure 1 This is a diagram showing the relationship between the sampling points on both sides of the protected power distribution line and the communication delay in the method of this invention.

[0053] Figure 2 The flowchart of the method of the present invention

[0054] Figure 3 This is a flowchart of the data transmission process of the method of the present invention;

[0055] Figure 4 This is a flowchart of the data receiving process of the present invention;

[0056] Figure 5 This is a flowchart of the clock synchronization method of the present invention;

[0057] Figure 6 This is a schematic diagram illustrating an application of the method of the present invention in 5G.

[0058] Figure 7 This is a structural diagram of the system of the present invention. Detailed Implementation

[0059] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0060] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0061] Example 1:

[0062] like Figure 1As shown, after receiving the protection data from the N-side device, the M-side device performs protection algorithm processing. Due to the influence of channel delay, the data processed at this time is the sampled data at time M3 and the sampled data at time N1. According to the principle of differential protection, the M3 data should be paired with the N3 data, and the N1 data should be paired with the M1 data in order to correctly apply the differential algorithm.

[0063] Based on this, the present invention proposes a method for data synchronization of differential protection in power distribution lines, such as... Figure 2 Shown, including:

[0064] S1. A millisecond pulse is generated by the protection device on the M / N side of the protected power distribution line, and the millisecond pulses are counted. If the count output value T of the millisecond pulses is... c The data transmission period T for the M / N side protection device s If the remainder is zero, then the current time is determined to be the data transmission time of the M / N side protection device;

[0065] S2, latch the counting output value T c The count output value T c As a time stamp, it is added to the differential protection data of the M / N side protection device at the current moment, and the differential protection data with the time stamp is packaged to obtain the packaged data;

[0066] S3. Cache the packaged data locally, and send the packaged data of the M-side protection device to the N-side protection device, and send the packaged data of the N-side protection device to the M-side protection device;

[0067] S4. When the M / N side protection device receives the packaged data, it extracts the timestamp from the packaged data and matches the timestamp extracted from the packaged data with the timestamp of the locally cached packaged data. If the match is consistent, the differential protection data synchronization is completed.

[0068] Before step S1, the present invention further includes:

[0069] Establish communication between the protection devices on the M and N sides, and minimize communication delay;

[0070] Synchronize the time for the protection devices on the M and N sides.

[0071] The data transmission cycle T of the control M and N side protection devices s Less than the maximum communication delay of the protection devices on the M and N sides.

[0072] In steps S1-3, the M / N side protection device includes a high-precision crystal oscillator and a counter, with the high-precision crystal oscillator serving as a millisecond timer;

[0073] The millisecond timer generates millisecond pulses by cyclically resetting its timer value to zero.

[0074] The counter increments by 1 when the millisecond timer generates a millisecond pulse.

[0075] Steps S1-3 in this invention can be considered as the data transmission process, specifically as follows: Figure 3 Shown, including:

[0076] The protection device uses a high-precision crystal oscillator to implement a 1-millisecond timer. The timer value is cyclically cleared to zero and generates millisecond pulses.

[0077] Design and implement a counter that increments by 1 every millisecond pulse, with the counter output value being T. c .

[0078] Let the data transmission period be T. s (milliseconds), then determine the current value T of the counter. c For T s Checking the remainder to determine if it is zero is equivalent to determining if it is the time to send a message.

[0079] If the current time is the same as the sending time, then latch the current time T. c The value is then used as a time stamp in the sampled data.

[0080] The packaged data packet is cached locally.

[0081] The packaged data is sent to the device on the other side.

[0082] In step S4, after the matching is complete, the packet data locally cached by the M-side protection device and the packet data received from the N-side protection device are processed by a differential protection algorithm.

[0083] If a match fails, the received packaged data is discarded, and the number of failed matches is determined. If the number of failed matches exceeds a set value N, the data will be further processed. s If the channel delay is abnormal, the differential protection will be blocked. This will occur when N consecutive [times / times / conditions] are [affected / interrupted]. s After a matching is successful, the interlocking differential protection is deactivated.

[0084] Step S4 and the above steps, in the context of this invention, can be considered as a data reception and synchronization process, specifically as follows: Figure 4 Shown, including:

[0085] It detects in real time whether it receives data sent from the other device.

[0086] Once data from the other side is detected, the timestamp information of the data from the other side is extracted and matched with the timestamp in the local cache data.

[0087] If data with the same time stamp is matched in the local cache, the data is retrieved and processed together with the data from the other side using the differential protection algorithm.

[0088] If the data on the other side cannot be matched locally, the data is considered to have failed to match, the current data is discarded, and the number of consecutive failed matches is determined.

[0089] If the number of failed matches has exceeded the set value N s If the channel delay is abnormal, the differential protection is considered to be blocked until data is re-matched and the situation stabilizes at N. s After the first match, the protection interlock is exited and the protection logic is restored.

[0090] The method of the present invention also includes time synchronization of the millisecond timer and counter, including:

[0091] If the millisecond timer and counter detect a time synchronization signal, the millisecond timer and counter are reset and restarted to synchronize with the time synchronization signal.

[0092] If the millisecond timer and counter do not detect the time synchronization signal, determine whether the time synchronization signal has timed out. If the time synchronization has timed out, determine the number of timeouts. If the number of timeouts is less than a set value N... a Then, the millisecond timer and counter are reset. If the number of timeouts is greater than or equal to the set value N, the timeout will be reset. a If the timing is abnormal, the differential protection will be locked out. This will occur if N consecutive cycles occur. a When the calibration signal arrives, the differential protection is deactivated.

[0093] The counter's full value is 1000 + Δn, and when the count output value T... c If the value is ≥1000+Δn, the time synchronization will time out.

[0094] Δn is the allowable timeout for a single instance, Δn×N a ≤T pmax T pmax The maximum clock difference allowed for differential protection.

[0095] Specifically, such as Figure 5 Shown, including:

[0096] When a time synchronization signal is detected, the system millisecond timer and system millisecond counter are reset and restarted to synchronize with the time synchronization signal.

[0097] If no time synchronization signal is detected, it is determined whether the time synchronization signal has timed out. The time synchronization signal is a signal with a period of 1 second. The full value of the system millisecond counter is set to 1000 + Δn, where Δn is the allowable timeout for a single timeout. When the count value of the millisecond counter is ≥1000 + Δn, the time synchronization is considered to have timed out.

[0098] When the number of timeouts is less than the set value N a The millisecond counter overflows and resets itself, simultaneously resetting the millisecond timer.

[0099] When the number of timeouts is greater than or equal to N a If the timing is abnormal, the differential protection will be locked until N consecutive times. a If a time synchronization pulse is detected, the protection interlock is released and the time synchronization logic is restored.

[0100] Specifically, Δn and N a The setting should follow Δn×N. a ≤T pmax T pmax The maximum clock difference allowed by differential protection will directly cause the sampling of devices on both sides of the protected line to be out of sync. Therefore, this value should be as small as possible, in principle, as long as the second pulse timeout can be detected.

[0101] This invention can be applied to 5G communication, such as... Figure 6 As shown, 5G communication is used for data transmission between the devices on both sides of the line protection.

[0102] It uses GPS / BD satellite time synchronization.

[0103] The data transmission cycle of the protection devices on both sides of the protected line is set to T. s =10ms, assuming the maximum 5G communication delay T cmax =20ms, additional tolerance N t =1, then the applicable cache depth N c =4, which can tolerate network latency ≤30ms, meaning the device will not fail to operate under this network latency condition.

[0104] The number of consecutive data matching failures N s Set it to 5.

[0105] The allowable timeout for a single time synchronization is Δn, which is 100µs.

[0106] Continuous time synchronization timeout number setting N a Set it to 5.

[0107] This invention also proposes a system 200 suitable for data synchronization of differential protection in power distribution lines, such as... Figure 7 Shown, including:

[0108] Initial unit 201 is used to generate millisecond pulses through the protection device on the M / N side of the protected distribution line, and to count the millisecond pulses. If the count output value T of the millisecond pulses is... c The data transmission period T for the M / N side protection device s If the remainder is zero, then the current time is determined to be the data transmission time of the M / N side protection device;

[0109] Data packaging unit 202 is used to latch the counting output value T c The count output value T c As a time stamp, it is added to the differential protection data of the M / N side protection device at the current moment, and the differential protection data with the time stamp is packaged to obtain the packaged data;

[0110] The data sending unit 203 is used to cache the packaged data locally, and send the packaged data of the M-side protection device to the N-side protection device, and send the packaged data of the N-side protection device to the M-side protection device.

[0111] The data synchronization unit 204 is used to extract the timestamp from the packaged data after the protection device on the M / N side receives the packaged data, and match the timestamp extracted from the packaged data with the timestamp of the locally cached packaged data. If the match is consistent, the differential protection data synchronization is completed.

[0112] After a match is found, differential protection algorithm processing is performed on the packaged data locally cached by the M-side protection device and the packaged data received from the N-side protection device.

[0113] If a match fails, the received packaged data is discarded, and the number of failed matches is determined. If the number of failed matches exceeds a set value N, the system will take further action. s If the channel delay is abnormal, the differential protection will be blocked. This will occur when N consecutive [times / times / conditions] are [affected / interrupted]. s After a matching is successful, the interlocking differential protection is deactivated.

[0114] The M / N side protection device includes a high-precision crystal oscillator and a counter, with the high-precision crystal oscillator serving as a millisecond timer.

[0115] The millisecond timer generates millisecond pulses by cyclically resetting its timer value to zero.

[0116] The counter increments by 1 when the millisecond timer generates a millisecond pulse.

[0117] The system also includes a time synchronization unit 205, used for synchronizing the millisecond timer and counter, including:

[0118] If the millisecond timer and counter detect a time synchronization signal, the millisecond timer and counter are reset and restarted to synchronize with the time synchronization signal.

[0119] If the millisecond timer and counter do not detect the time synchronization signal, determine whether the time synchronization signal has timed out. If the time synchronization has timed out, determine the number of timeouts. If the number of timeouts is less than a set value N... a Then, the millisecond timer and counter are reset. If the number of timeouts is greater than or equal to the set value N, the timeout will be reset. a If the timing is abnormal, the differential protection will be locked out. This will occur if N consecutive cycles occur. a When the calibration signal arrives, the differential protection is deactivated.

[0120] The full value of the counter is 1000 + Δn, and the count output value T is... c If the value is ≥1000+Δn, the time synchronization will time out.

[0121] Where Δn is the allowable timeout for a single instance, Δn×N a ≤T pmax T pmax The maximum clock difference allowed for differential protection.

[0122] The initial unit 201 is also used for:

[0123] Establish communication between the protection devices on the M and N sides, and minimize communication delay;

[0124] Synchronize the time for the protection devices on the M and N sides.

[0125] The initial unit 201 is also used for:

[0126] The data transmission cycle T of the control M and N side protection devices s Less than the maximum communication delay of the protection devices on the M and N sides.

[0127] When differential data is matched according to the method described in this invention, the data participating in the differential protection processing after receiving the protection data from the other side is no longer the current local sampling data, but the cached data that matches the time stamp of the data from the other side, thus ensuring the consistency of the matched data in time.

[0128] In the method described in this invention, the buffer depth is related to the data transmission period and the communication latency. Let the data transmission period be T. s The actual maximum communication delay is T. cmax The applicable cache depth N is... c =(T cmax / T s )+1+N t .

[0129] Where N t For additional latency tolerance, a value of 1 is generally sufficient.

[0130] This invention addresses communication delay. <T cmax In this case, the correct data can be reliably matched, ensuring the correctness of the differential protection algorithm data and solving the problem of inconsistent sampling time of the calculated data caused by channel delay.

[0131] The method described in this invention relies on an accurate and stable time synchronization signal. When the time synchronization signal is abnormal, this invention uses its own timer to reset it. The cost of the self-reset method is the lag in the reset time. When the time synchronization signal occasionally times out or is lost, this method relies on the high-precision crystal oscillator of the protection device to ensure the normal operation of the differential protection logic and improve the anti-interference capability of the time synchronization signal on which it depends.

[0132] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0133] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0134] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1The function specified in one or more boxes.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0136] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0137] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for synchronizing differential protection data in power distribution lines, characterized in that, The method includes: The protection device on the M / N side of the protected power distribution line generates millisecond pulses and counts them. If the count output value T of the millisecond pulses is... c The data transmission period T for the M / N side protection device s If the remainder is zero, then the current time is determined to be the data transmission time of the M / N side protection device; Among these measures, communication between the protection devices on the M and N sides is established, and the communication delay is minimized. Synchronization time for protection devices on both the M and N sides; The data transmission cycle T of the control M and N side protection devices s Less than the maximum communication delay of the protection devices on the M and N sides; Latch the count output value T c The count output value T c As a time stamp, it is added to the differential protection data of the M / N side protection device at the current moment, and the differential protection data with the time stamp is packaged to obtain the packaged data; The packaged data is cached locally, and the packaged data of the M-side protection device is sent to the N-side protection device, and the packaged data of the N-side protection device is sent to the M-side protection device. When the M / N side protection device receives the packaged data, it extracts the timestamp from the packaged data and matches the timestamp extracted from the packaged data with the timestamp of the locally cached packaged data. If the match is consistent, the differential protection data synchronization is completed.

2. The method according to claim 1, characterized in that, After the matching is successful, the packaged data locally cached by the M-side protection device and the packaged data received from the N-side protection device are processed by a differential protection algorithm.

3. The method according to claim 1, characterized in that, If the matching fails, the received packaged data is discarded, and the number of matching failures is determined. If the number of matching failures exceeds a set value N, the data is considered lost. s If the channel delay is abnormal, the differential protection will be blocked. This will occur when N consecutive [times / times / conditions] are [affected / interrupted]. s After a matching is successful, the interlocking differential protection is deactivated.

4. The method according to claim 1, characterized in that, The M / N side protection device includes a high-precision crystal oscillator and a counter, with the high-precision crystal oscillator serving as a millisecond timer. The millisecond timer generates millisecond pulses by cyclically resetting its timer value to zero. The counter increments by 1 when the millisecond timer generates a millisecond pulse.

5. The method according to claim 4, characterized in that, The method further includes calibrating the millisecond timer and counter, including: If the millisecond timer and counter detect a time synchronization signal, the millisecond timer and counter are reset and restarted to synchronize with the time synchronization signal. If the millisecond timer and counter do not detect the time synchronization signal, determine whether the time synchronization signal has timed out. If the time synchronization has timed out, determine the number of timeouts. If the number of timeouts is less than a set value N... a Then, the millisecond timer and counter are reset. If the number of timeouts is greater than or equal to the set value N, the timeout will be reset. a If the timing is abnormal, the differential protection will be locked out. This will occur if N consecutive cycles occur. a When the calibration signal arrives, the differential protection is deactivated.

6. The method according to claim 5, characterized in that, The counter has a full value of 1000 + Δn, and the count output value T c If the value is ≥1000+Δn, the time synchronization will time out. Where Δn is the allowable timeout for a single instance, Δn×N a ≤T pmax T pmax The maximum clock difference allowed for differential protection.

7. A system for synchronizing differential protection data in power distribution lines, characterized in that, The system includes: The initial unit is used to generate millisecond pulses through the protection device on the M / N side of the protected distribution line, and to count the millisecond pulses. If the count output value T of the millisecond pulses is... c The data transmission period T for the M / N side protection device s If the remainder is zero, then the current time is determined to be the data transmission time of the M / N side protection device; Among these measures, communication between the protection devices on the M and N sides is established, and the communication delay is minimized. Synchronization time for protection devices on both the M and N sides; The data transmission cycle T of the control M and N side protection devices s Less than the maximum communication delay of the protection devices on the M and N sides; The data packaging unit is used to latch the counting output value T. c The count output value T c As a time stamp, it is added to the differential protection data of the M / N side protection device at the current moment, and the differential protection data with the time stamp is packaged to obtain the packaged data; The data sending unit is used to cache the packaged data locally and send the packaged data of the M-side protection device to the N-side protection device, and send the packaged data of the N-side protection device to the M-side protection device. The data synchronization unit is used to extract the timestamp from the packaged data after the protection device on the M / N side receives the packaged data, and match the timestamp extracted from the packaged data with the timestamp of the locally cached packaged data. If the match is consistent, the differential protection data synchronization is completed.

8. The system according to claim 7, characterized in that, After the matching is successful, the packaged data locally cached by the M-side protection device and the packaged data received from the N-side protection device are processed by a differential protection algorithm.

9. The system according to claim 7, characterized in that, If the matching fails, the received packaged data is discarded, and the number of matching failures is determined. If the number of matching failures exceeds a set value N, the data is considered lost. s If the channel delay is abnormal, the differential protection will be blocked. This will occur when N consecutive [times / times / conditions] are [affected / interrupted]. s After a matching is successful, the interlocking differential protection is deactivated.

10. The system according to claim 7, characterized in that, The M / N side protection device includes a high-precision crystal oscillator and a counter, with the high-precision crystal oscillator serving as a millisecond timer. The millisecond timer generates millisecond pulses by cyclically resetting its timer value to zero. The counter increments by 1 when the millisecond timer generates a millisecond pulse.

11. The system according to claim 10, characterized in that, The system further includes a time synchronization unit for synchronizing the millisecond timer and counter, including: If the millisecond timer and counter detect a time synchronization signal, the millisecond timer and counter are reset and restarted to synchronize with the time synchronization signal. If the millisecond timer and counter do not detect the time synchronization signal, determine whether the time synchronization signal has timed out. If the time synchronization has timed out, determine the number of timeouts. If the number of timeouts is less than a set value N... a Then, the millisecond timer and counter are reset. If the number of timeouts is greater than or equal to the set value N, the timeout will be reset. a If the timing is abnormal, the differential protection will be locked out. This will occur if N consecutive cycles occur. a When the calibration signal arrives, the differential protection is deactivated.

12. The system according to claim 11, characterized in that, The counter has a full value of 1000 + Δn, and the count output value T c If the value is ≥1000+Δn, the time synchronization will time out. Where Δn is the allowable timeout for a single instance, Δn×N a ≤T pmax T pmax The maximum clock difference allowed for differential protection.

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