Sampling synchronization method for differential protection device, differential protection device and system

Abstract

The present disclosure relates to a sampling synchronization method for a differential protection device arranged at one end of a data channel as an adjustment end device and another differential protection device arranged at the other end of the data channel as a reference end device. According to the sampling synchronization method, sampling synchronization operation is started once in each adjusting end sampling period. The sampling synchronization operation comprises the following steps: sending a first message to the reference end device; receiving a second message sent by the reference end device; determining the sampling time deviation of the adjusting end device and the reference end device; and adjusting the sampling time of the first adjusting end after the sampling synchronization operation is completed based on the sampling time deviation. The invention further relates to a differential protection device and a system for differential protection.

Description

Technical Field

[0001] The present disclosure relates to the field of relay protection, and in particular to a sampling synchronization method for a differential protection device, a differential protection device, and a system for differential protection. Background Art

[0002] Differential protection is a commonly used relay protection method. It determines whether there is a fault in the protection zone by detecting the current imbalance in the protection zone, so as to perform corresponding protection actions, such as triggering a circuit breaker. Differential protection devices are usually set at both ends of the protection zone. Ensuring the synchronization of the sampling data collected by the differential protection devices on both sides is the key to the safety and reliability of differential protection. In practical applications, sampling time errors are caused by the inconsistency of the clocks of the differential protection devices on both sides and the drift of the crystal oscillator.

[0003] The mainstream solution is to perform sampling synchronization based on the Fourier algorithm. However, sampling synchronization based on the Fourier algorithm cannot provide fault recording containing data from both sides, making it difficult to perform subsequent fault analysis, and the fault detection generated when the inductor used for current sensing and monitoring is saturated affects the Fourier calculation results, making data acquisition inaccurate. Inductor detection with the help of the Fourier algorithm requires at least one cycle of data sampling, resulting in a differential protection delay of approximately 20ms. In addition, after the sampled data is Fourier calculated and rotated, additional error current will be introduced in the sampling synchronization, reducing the protection sensitivity and protection action time. Summary of the invention

[0004] In order to solve the above problems, the present disclosure provides a sampling synchronization method for a differential protection device, a differential protection device and a system for differential protection, which can achieve simpler, more accurate and reliable sampling synchronization without the need for Fourier transform of sampled data and without the need for an external time source.

[0005] The embodiment of the present disclosure provides a sampling synchronization method for a differential protection device, wherein the differential protection device is arranged at one end of a data channel as an adjustment end device, and another differential protection device is arranged at the other end of the data channel as a reference end device. The sampling synchronization method starts a sampling synchronization operation in each adjustment end sampling cycle, and the two ends of the adjustment end sampling cycle are the adjustment end sampling moments.

[0006] The sampling synchronization operation includes: sending a first message to the reference end device, the first message including the adjustment end sampling data sampled at the adjustment end sampling moment at the starting point of the adjustment end sampling period; receiving a second message sent by the reference end device, the second message including the reference end receiving moment when the reference end device receives the first message, the reference end sending moment when the reference end device sends the second message, the first reference end sampling moment after the reference end receiving moment, and the reference end sampling data sampled at the first reference end sampling moment; determining the sampling moment deviation between the adjustment end device and the reference end device based on the moment of sending the first message, the moment of receiving the second message, the reference end receiving moment, the reference end sending moment, the first reference end sampling moment and the first adjustment end sampling moment after the starting point adjustment end sampling moment; and adjusting the first adjustment end sampling moment after the completion of the sampling synchronization operation based on the sampling moment deviation.

[0007] According to an embodiment of the present disclosure, determining the sampling time deviation between the adjustment end device and the reference end device includes: calculating the channel delay of the data channel based on the following formula:

[0008] T d =(T2'-T1'-(T2-T1)) / 2

[0009] And the sampling time deviation is calculated based on the following formula:

[0010] T o =T2'-T d -(T2-T B2 )-T A2

[0011] Wherein, T1' is the time when the first message is sent, T1 is the time when the reference end receives, T2 is the time when the reference end sends, T2' is the time when the second message is received, T B2 is the first reference end sampling time, T A2 It is the first adjustment end sampling time after the start adjustment end sampling time.

[0012] According to an embodiment of the present disclosure, the determining factor of the reference end sending time includes a predetermined message processing period.

[0013] According to an embodiment of the present disclosure, when the time interval between the reference end receiving moment and the first reference end sampling moment is greater than the message processing period, the reference end sending moment is the first reference end sampling moment; and when the time interval between the reference end receiving moment and the first reference end sampling moment is less than or equal to the message processing period, the reference end sending moment is the moment when the message processing period is completed.

[0014] According to an embodiment of the present disclosure, the first adjustment end sampling moment after the sampling synchronization operation is completed based on the sampling moment deviation includes: setting an adjustment step and comparing the adjustment step with the sampling moment deviation; when the adjustment step is less than the sampling moment deviation, adjusting the first adjustment end sampling moment after the sampling synchronization operation is completed with the adjustment step; and when the adjustment step is greater than or equal to the sampling moment deviation, adjusting the first adjustment end sampling moment after the sampling synchronization operation is completed with the sampling moment deviation to eliminate the sampling moment deviation.

[0015] According to an embodiment of the present disclosure, the first adjustment end sampling moment after the sampling synchronization operation is completed based on the sampling moment deviation includes: setting an adjustment step and a deviation threshold, and comparing the sampling moment deviation with the deviation threshold, when the sampling moment deviation is greater than or equal to the deviation threshold, adjusting the first adjustment end sampling moment after the sampling synchronization operation is completed with the adjustment step; and when the sampling moment deviation is less than the deviation threshold, not adjusting the first adjustment end sampling moment after the sampling synchronization operation is completed.

[0016] According to an embodiment of the present disclosure, the adjustment step length is less than 10 μs.

[0017] According to an embodiment of the present disclosure, the deviation threshold is less than 10 μs.

[0018] An embodiment of the present disclosure provides a differential protection device, including: a processor; and a memory, wherein an executable program is stored in the memory, and when the executable program is executed by the processor, the sampling synchronization method according to the present disclosure is executed.

[0019] An embodiment of the present disclosure provides a system for differential protection, comprising a first differential protection device and a second differential protection device respectively arranged at two ends of the system. The first differential protection device is a differential protection device according to the present disclosure. The second differential protection device is a differential protection device as a reference end device according to the present disclosure, wherein the reference end device is capable of receiving a first message at a reference end receiving time and sending a second message at a reference end sending time.

[0020] According to the sampling synchronization method of the embodiment of the present disclosure, the sampling moment of the differential protection device on one side is synchronized with the differential protection device on the other side, so as to obtain the original sampling data of the same absolute moment on this side and the opposite side, without the need to transform the sampling data. Furthermore, according to the sampling synchronization method of the embodiment of the present disclosure, the sending and receiving of the sampling data on this side are combined with the sampling synchronization operation on this side, which simplifies the implementation of the sampling synchronization method and the design of the differential protection device. Moreover, since the sampling synchronization operation is started once in each adjustment end sampling cycle, the sampling synchronization can be monitored and guaranteed in real time and continuously throughout the differential protection process. In addition, the sampling synchronization method of the embodiment of the present disclosure does not require an external time source independent of the adjustment end device and the reference end device, which simplifies the implementation of the sampling synchronization method and the design of the differential protection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some exemplary embodiments of the present disclosure, and a person of ordinary skill in the art can obtain other drawings based on these drawings without creative work.

[0022] Figure 1 A flow chart schematically shows a sampling synchronization method and a sampling synchronization operation for a differential protection device according to an embodiment of the present disclosure;

[0023] Figure 2 The method for calculating the sampling time deviation according to the embodiment of the present disclosure is schematically illustrated with a message propagation example diagram;

[0024] Figure 3 A schematic diagram of a differential protection device according to an embodiment of the present disclosure is shown;

[0025] Figure 4 A schematic diagram of a system for differential protection according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present disclosure more obvious, the exemplary embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments of the present disclosure, and it should be understood that the present disclosure is not limited to the exemplary embodiments described here.

[0027] In this specification and the accompanying drawings, substantially the same or similar steps and elements are represented by the same or similar reference numerals, and repeated descriptions of these steps and elements will be omitted. At the same time, in the description of the present disclosure, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance or ranking.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure pertains. The terms used herein are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

[0029] To facilitate description of the present disclosure, concepts related to the present disclosure are introduced below.

[0030] Differential protection: A local protection for a protected section of a power system, based on the comparison of the currents at both ends of the protected section. Differential protection is based on Kirchhoff's current law, and in the event of a fault, the currents at both ends of the protected section deviate significantly from the balance.

[0031] Data channel: for example, an optical fiber channel, through which the differential protection device on this side sends sampling data on this side to the differential protection device on the opposite side and receives sampling data on the opposite side.

[0032] Clock: The differential protection device performs sampling based on an internal clock.

[0033] Sampling time: The differential protection devices perform sampling at the relative sampling time on their own side. Since the differential protection devices on both sides may have clock inconsistencies, the absolute sampling times of the differential protection devices on both sides are inconsistent.

[0034] Adjustment end device and reference end device: According to the embodiments of the present disclosure, the differential protection devices on both sides are respectively set to be used as the adjustment end device and the reference end device in the sampling synchronization method. The reference end device does not perform sampling synchronization adjustment, and its sampling time is used as a reference benchmark. The adjustment end device adjusts the sampling time on this side based on the sampling time deviation, so as to synchronize the sampling time of the adjustment end device with the sampling time of the reference end device.

[0035] Figure 1 The flowchart schematically shows a sampling synchronization method and a sampling synchronization operation for a differential protection device according to an embodiment of the present disclosure.

[0036] like Figure 1As shown on the left, the sampling synchronization method for a differential protection device according to an embodiment of the present disclosure can start a sampling synchronization operation in each adjustment end sampling cycle (e.g., the first adjustment end sampling cycle, the second adjustment end sampling cycle, the third adjustment end sampling cycle, etc.), ensuring that each local sampling moment of the differential protection device arranged at one end of the data channel as an adjustment end device, that is, the adjustment end sampling moment, is associated with a sampling synchronization operation. This achieves continuous synchronous monitoring and adjustment of the sampling synchronization method according to an embodiment of the present disclosure.

[0037] The two ends of the adjustment end sampling period may be, for example, adjustment end sampling moments, wherein the starting end may be, for example, an adjustment end sampling moment, also referred to as a starting adjustment end sampling moment hereinafter, and the ending end may be another adjustment end sampling moment. For example, one or more adjustment end sampling moments may be spanned between the ending end and the starting end.

[0038] Since each adjustment end sampling moment corresponds to an adjustment end sampling period, and the sampling synchronization operation performed in the adjustment end sampling period is not necessarily completed within the adjustment end sampling interval between successive adjustment end sampling moments, the adjustment end sampling periods may overlap in time, for example. Figure 1 The sequence of arrows shown on the left side only indicates the order in which the adjustment end sampling cycles occur, and does not mean that, for example, the second adjustment end sampling cycle will only begin after the first adjustment end sampling cycle ends.

[0039] like Figure 1 As shown on the right, according to an embodiment of the present disclosure, the sampling synchronization operation started and executed in each adjustment end sampling cycle may include four steps. Figure 2 The sampling synchronization operation is described in detail.

[0040] In the first step S1, for example, a first message may be sent to the reference terminal device, which schematically corresponds to Figure 2 The process is shown by the solid line with an arrow and the endpoint is T1'.

[0041] The first message may include, for example, the adjustment end sampling data sampled at the adjustment end sampling time at the start point of the adjustment end sampling period. Optionally, the first message also includes the adjustment end sampling time at the start point. Optionally, the first message also includes data that may be required, such as a sampling synchronization instruction or message verification information.

[0042] Preferably, the time when the first message is sent is the sampling time of the start point adjustment end. Optionally, the time when the first message is sent is later than the sampling time of the start point adjustment end.

[0043] In the second step S2, for example, a second message sent by the reference terminal device may be received, which schematically corresponds to Figure 2The process is shown by the solid line with an arrow and the endpoint is T2'.

[0044] The second message may, for example, include the reference end receiving time when the reference end device receives the first message, the reference end sending time when the reference end device sends the second message, the first reference end sampling time after the reference end receiving time, and the reference end sampling data sampled at the first reference end sampling time.

[0045] The determining factors of the reference end sending time may include, for example, a predetermined message processing period.

[0046] After receiving the first message, the reference end device can process, for example, parse the first message within a predetermined message processing period, so as to obtain the adjustment end sampling data in the first message to perform differential protection analysis, and optionally obtain the sampling synchronization instruction, so as to return the corresponding data in the second message. The predetermined message processing period can be specified by the user as needed, so that the message processing can be completed within the message processing period regardless of the length of the first message.

[0047] Since the second message needs to include the reference end sampling data sampled by the reference end device at a reference end sampling time, the reference end must span a reference end sampling time from the reference end receiving time of receiving the first message to the reference end sending time of sending the second message. The reference end sampling time is preferably the first reference end sampling time after the reference end receiving time.

[0048] Preferably, when the time interval between the reference end receiving time and the first reference end sampling time is greater than the above-mentioned message processing period, the reference end sending time is the first reference end sampling time. When the time interval between the reference end receiving time and the first reference end sampling time is less than or equal to the above-mentioned message processing period, the reference end sending time is the time when the message processing period is completed.

[0049] Optionally, the reference end sending moment is the first reference end sampling moment after the reference end receiving moment, and has nothing to do with the message processing period. This concept is based on the fact that the reference end device processes the first message in order to obtain the adjustment end sampling data, and this process does not affect the sampling synchronization relationship between the adjustment end and the reference end. The reference end device can send a second message containing the reference end sampling data after sampling at the first reference end sampling moment, regardless of whether the first message has been processed. In this way, for example, the duration of the sampling synchronization operation can be shortened. However, since it does not consider whether the first message has been processed, and the second message is returned without obtaining the message verification information or message integrity information that may be contained in the first message, the reliability of the sampling synchronization method may be reduced.

[0050] In the third step S3, for example, the sampling time deviation between the adjustment end device and the reference end device can be determined based on the time of sending the first message, the time of receiving the second message, the reference end receiving time, the reference end sending time, the first reference end sampling time after the reference end receiving time, and the first adjustment end sampling time after the starting point adjustment end sampling time. The adjustment end device obtains the time of sending the first message and the first adjustment end sampling time after the starting point adjustment end sampling time on its side, and the other times involved in the calculation are obtained by the second message received in the second step S2.

[0051] In the fourth step S4, for example, the first adjustment end sampling time after the sampling synchronization operation is completed can be adjusted based on the calculated sampling time deviation. In other words, after calculating the latest sampling time deviation between the adjustment end device and the reference end device, the upcoming adjustment end sampling time is adjusted so that the sampling time deviation is reduced.

[0052] As described above, the sampling synchronization operation performed in the adjustment end sampling cycle is not necessarily completed within the adjustment end sampling interval between consecutive adjustment end sampling moments, so after the latest sampling moment deviation is calculated in the sampling synchronization operation, the first adjustment end sampling moment after the sampling synchronization operation is completed is adjusted based on the sampling moment deviation. For example, if the sampling synchronization operation of the first adjustment end sampling cycle is completed and the third adjustment end sampling cycle is to be entered, the starting adjustment end sampling moment of the third adjustment end sampling cycle is adjusted based on the sampling moment deviation calculated in the first adjustment end sampling cycle.

[0053] The adjustment of the sampling moment of the adjustment end may include, for example, setting an adjustment step and comparing the adjustment step with the calculated sampling moment deviation. When the adjustment step is less than the sampling moment deviation, the first adjustment end sampling moment after the sampling synchronization operation is completed may be adjusted with the adjustment step, that is, the sampling moment deviation is reduced by the adjustment step. When the adjustment step is greater than or equal to the sampling moment deviation, for example, the first adjustment end sampling moment after the sampling synchronization operation is completed may be directly adjusted with the sampling moment deviation, so that the sampling moment deviation is eliminated. In this way, the sampling synchronization accuracy can be greatly improved, thereby improving the accuracy of differential protection.

[0054] Alternatively, the adjustment of the sampling moment of the adjustment end may include, for example, setting an adjustment step and a deviation threshold, and comparing the sampling moment deviation with the deviation threshold. When the sampling moment deviation is greater than or equal to the deviation threshold, the first adjustment end sampling moment after the sampling synchronization operation is completed is adjusted with the adjustment step. When the sampling moment deviation is less than the deviation threshold, it can be regarded that the adjustment end device has been synchronized with the reference end device, and therefore the first adjustment end sampling moment after the sampling synchronization operation is completed is not adjusted. In this way, a high sampling synchronization accuracy can be guaranteed while reducing the computational overhead of the differential protection device.

[0055] According to an embodiment of the present disclosure, the adjustment step size is optionally less than 10 μs, preferably 5 μs, 2 μs, and other suitable adjustment step size values ​​are also conceivable. The smaller the adjustment step size, the higher the synchronization accuracy.

[0056] According to an embodiment of the present disclosure, the deviation threshold may be less than 10 μs, preferably 5 μs or 2 μs, and other suitable deviation thresholds may also be considered.

[0057] According to the sampling synchronization method according to the embodiment of the present disclosure, the sampling moment deviation is gradually reduced with an adjustment step in each adjustment end sampling cycle, ensuring that the adjustment amplitude of each sampling moment is small, so that the deviation of successive sampling data, such as the change in the phase angle of the current, will not be very large, effectively avoiding false protection actions.

[0058] Optionally, the adjustment-end sampling data and the reference-end sampling data are applied to the differential protection only after the adjustment-end device is synchronized with the reference-end device.

[0059] According to the sampling synchronization method of the embodiment of the present disclosure, the sampling moment of the differential protection device on one side is synchronized with that of the differential protection device on the other side, and the original sampling data of this side and the opposite side at the same absolute moment are obtained, so that the fault waveforms on both sides at the moment of the fault can be recorded, and the original data can be used for applications such as inductor monitoring in differential protection, making problem analysis simpler and more intuitive and running faster.

[0060] Further, according to the sampling synchronization method according to the embodiment of the present disclosure, the sending and receiving of the sampling data on this side are combined with the sampling synchronization operation on this side, instead of sending the sampling synchronization message separately from the transmission sampling data, which reduces the types and times of data to be transmitted, simplifies the implementation of the sampling synchronization method and the design of the differential protection device. In addition, since the sampling synchronization operation is started once in each adjustment end sampling cycle, the sampling synchronization can be monitored and guaranteed in real time and continuously throughout the differential protection process, meeting the requirements of long-term synchronization accuracy and uniform sampling, and thus also improving the reliability and accuracy of the differential protection.

[0061] In addition, the sampling synchronization method according to the embodiment of the present disclosure does not require a third clock (i.e., a common external time source) that is independent of the adjustment end device and the reference end device. It only needs to perform sampling synchronization operations within the adjustment end sampling period, that is, execute the sending, receiving and calculation of messages in the differential protection device set as the adjustment end device, so that the sampling moment of the adjustment end device is synchronized with the sampling moment of the reference end device, which simplifies the implementation of the sampling synchronization method and the design of the differential protection device.

[0062] Figure 2The method for calculating the sampling time deviation according to the embodiment of the present disclosure is schematically illustrated with a message propagation example diagram.

[0063] like Figure 2 As shown, the adjustment end devices AE are respectively at the adjustment end sampling time T A1 、T A2 、T A3 、T A4 、T A5 To perform sampling, the reference end device BE is respectively at the reference end sampling time T B1 、T B2 、T B3 、T B4 、T B5 Sampling is performed, and there is a sampling time deviation between the adjustment end sampling time and the reference end sampling time. For clarity, Figure 2 The example shown is only T A1 The time is the adjustment end sampling period of the starting point adjustment end sampling time, and the two ends of the adjustment end sampling period are T A1 Moment and T A4 time.

[0064] like Figure 2 As shown, the adjustment end device AE sends a first message M1 to the reference end device BE at time T1', and the time T1' may be, for example, T A1 The reference end device BE receives the first message M1 at the reference end receiving time T1, and sends the second message M2 at the reference end sending time T2. The second message includes the reference end receiving time T1, the reference end sending time T2, the first reference end sampling time T2 of the reference end device BE after the reference end receiving time T1, and the second message M2 sent by the reference end device BE at the reference end sending time T2. B2 And at the first reference end sampling time T B2 For the sake of clarity, the sampling time of the adjustment end device and the reference end device is indicated by a subscript with "A" or "B", and the time when the adjustment end device and the reference end device receive and send messages is indicated by a subscript without "A" or "B". In addition, the time on the local side of the reference end device BE is indicated by a superscript without "'", and the time on the local side of the adjustment end device AE is indicated by a superscript with "'".

[0065] After receiving the second message M2, for example, the channel delay T of the data channel can be calculated on the adjustment end device AE side based on the following formula: d :

[0066] T d = (T2'-T1'-(T2-T1)) / 2 (Formula 1)

[0067] The premise of Formula 1 is that the channel delays from the adjustment end device AE to the reference end device BE and from the reference end device BE to the adjustment end device AE are equal.

[0068] The channel delay T is calculated. d Then, for example, the sampling time deviation T can be calculated based on the following formula: o :

[0069] T o = T2' - T d -(T2-T B2 ) -T A2 (Formula 2)

[0070] Among them, T A2 The starting point of the adjustment end sampling period involved is the adjustment end sampling time T A1 In the embodiment shown, T o Indicates the sampling time T of the adjustment end A2 With the reference end sampling time T B2 The deviation between .

[0071] In T o <0, adjust the end sampling time T A2 Ahead of the reference sampling time T B2 , in T o >0, adjust the end sampling time T A2 Lagging behind the reference sampling time T B2 .

[0072] According to the calculation method of the sampling time deviation of the embodiment of the present disclosure, instead of directly calculating the time of the reference end device BE and the time of the adjustment end device AE, the adjustment end device AE calculates the difference between the time of the reference end device BE and the time of the reference end device BE (for example, (T2-T1) in Formula 1 and (T2-T2) in Formula 2). B2 )) is calculated, which effectively avoids the problem of inconsistent recorded absolute time caused by inconsistent clocks of the adjustment end device AE and the reference end device BE. For this reason, the second message can also directly include the above-mentioned time difference of the reference end device BE.

[0073] like Figure 2 As shown, when calculating the sampling time deviation T o Afterwards, the first adjustment end sampling time after the sampling synchronization operation is completed, that is, T A4 time.

[0074] According to the sampling time deviation calculation method of the embodiment of the present disclosure, the channel delay and sampling time deviation can be calculated within one sampling synchronization operation and the upcoming adjustment end sampling time can be adjusted. The calculation method is simple, that is, based on multiple times, without the need to transform the sampling data.

[0075] Figure 3 A schematic diagram of a differential protection device 100 according to an embodiment of the present disclosure is shown.

[0076] like Figure 3 As shown, the differential protection device 100 includes one or more processors 101 and one or more memories 102. The memory 102 stores an executable program, and when the processor 101 executes the executable program, the sampling synchronization method described above is executed. The above detailed description of the sampling synchronization method is also applicable to the differential protection device 100.

[0077] The processor in the embodiments of the present disclosure may be an integrated circuit chip having signal processing capabilities. The processor may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc., and may be an X86 architecture or an ARM architecture.

[0078] Figure 4 A schematic diagram of a system S for differential protection according to an embodiment of the present disclosure is shown.

[0079] like Figure 4 As shown, the system S for differential protection may include a first differential protection device DP1 and a second differential protection device DP2 respectively arranged at two ends of the system.

[0080] The first differential protection device DP1 may be, for example, a differential protection device according to an embodiment of the present disclosure. The second differential protection device DP2 may be, for example, a differential protection device as a reference end device according to an embodiment of the present disclosure, wherein the reference end device is capable of receiving a first message at a reference end receiving time and sending a second message at a reference end sending time.

[0081] The above detailed description on the sampling synchronization method and the differential protection device is also applicable to the system S for differential protection.

[0082] In general, various example embodiments of the present disclosure may be implemented in hardware or dedicated circuits, software, firmware, logic, or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. When various aspects of the embodiments of the present disclosure are illustrated or described as block diagrams, flow charts, or using some other graphical representation, it will be understood that the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general purpose hardware or controllers or other computing devices, or some combination thereof as non-limiting examples.

[0083] The exemplary embodiments of the present disclosure described in detail above are merely illustrative and not restrictive. It should be understood by those skilled in the art that various modifications and combinations may be made to these embodiments or their features without departing from the principles and spirit of the present disclosure, and such modifications should fall within the scope of the present disclosure.

Claims

1. A sampling synchronization method for a differential protection device, wherein the differential protection device is arranged at one end of a data channel as an adjustment end device, and another differential protection device is arranged at the other end of the data channel as a reference end device, wherein The sampling synchronization method starts a sampling synchronization operation once in each adjustment end sampling period, and both ends of the adjustment end sampling period are adjustment end sampling moments; and The sampling synchronization operation includes: Sending a first message to the reference end device, wherein the first message includes adjustment end sampling data sampled at the adjustment end sampling time at the starting point of the adjustment end sampling period, receiving a second message sent by the reference end device, the second message including a reference end receiving time when the reference end device receives the first message, a reference end sending time when the reference end device sends the second message, a first reference end sampling time after the reference end receiving time, and reference end sampling data sampled at the first reference end sampling time, determining a sampling time deviation between the adjustment end device and the reference end device based on a time of sending the first message, a time of receiving the second message, a reference end receiving time, a reference end sending time, the first reference end sampling time, and a first adjustment end sampling time after the starting adjustment end sampling time, and The first adjustment end sampling time after the sampling synchronization operation is completed is adjusted based on the sampling time deviation.

2. The sampling synchronization method according to claim 1, wherein: The determining of the sampling time deviation between the adjustment end device and the reference end device comprises: The channel delay of the data channel is calculated based on the following formula: T d =(T2’-T1’-(T2-T1)) / 2 And the sampling time deviation is calculated based on the following formula: T o =T2’-T d -(T2-T B2 )-T A2 Wherein, T1' is the time when the first message is sent, T1 is the time when the reference end receives, T2 is the time when the reference end sends, T2' is the time when the second message is received, T B2 is the first reference end sampling time, T A2 It is the first adjustment end sampling time after the starting point adjustment end sampling time.

3. The sampling synchronization method according to claim 1, wherein: The determining factors of the reference end sending time include a predetermined message processing period.

4. The sampling synchronization method according to claim 3, wherein: In the case where the time interval between the reference end receiving time and the first reference end sampling time is greater than the message processing period, the reference end sending time is the first reference end sampling time; and In the case where the time interval between the reference end receiving time and the first reference end sampling time is less than or equal to the message processing period, the reference end sending time is the time when the message processing period is completed.

5. The sampling synchronization method according to claim 1, wherein: The step of adjusting the first adjustment end sampling time after the sampling synchronization operation is completed based on the sampling time deviation comprises: Setting an adjustment step size and comparing the adjustment step size with the sampling time deviation, When the adjustment step is smaller than the sampling time deviation, the first adjustment end sampling time after the sampling synchronization operation is completed is adjusted with the adjustment step, and When the adjustment step is greater than or equal to the sampling time deviation, the first adjustment end sampling time after the sampling synchronization operation is completed is adjusted with the sampling time deviation to eliminate the sampling time deviation.

6. The sampling synchronization method according to claim 1, wherein: The step of adjusting the first adjustment end sampling time after the sampling synchronization operation is completed based on the sampling time deviation comprises: Setting an adjustment step size and a deviation threshold, and comparing the sampling time deviation with the deviation threshold, When the sampling time deviation is greater than or equal to the deviation threshold, the first adjustment end sampling time after the sampling synchronization operation is completed is adjusted with the adjustment step size, and When the sampling time deviation is less than the deviation threshold, the first adjustment end sampling time after the sampling synchronization operation is completed is not adjusted.

7. The sampling synchronization method according to claim 5 or 6, wherein: The adjustment step length is less than 10 μs.

8. The sampling synchronization method according to claim 6, wherein: The deviation threshold is less than 10 μs.

9. A differential protection device, comprising: processor; as well as A memory having an executable program stored therein, wherein when the executable program is executed by the processor, the sampling synchronization method according to any one of claims 1 to 8 is executed.

10. A system for differential protection, comprising a first differential protection device and a second differential protection device respectively arranged at two ends of the system, wherein: The first differential protection device is the differential protection device according to claim 9, The second differential protection device is a differential protection device as a reference end device according to any one of claims 1 to 8, wherein the reference end device is capable of receiving the first message at the reference end receiving time and sending the second message at the reference end sending time.

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