A differential protection method and system suitable for communication delay uncertainty

Abstract

The application discloses a differential protection method and system suitable for communication delay uncertainty, wherein the method comprises the following steps: a real-time sampling data is stored in different data buffer areas according to the distance from the current sampling time by a local differential protection device; the real-time sampling data sent by a remote differential protection device through an unknown time delay communication channel is received; the local real-time sampling data of the same sampling time is matched from the data buffer area of the local differential protection device according to the sampling time of the remote differential protection device; the extraction rate required by the remote real-time sampling data is calculated and extraction is performed; and then the extracted remote real-time sampling data is subjected to differential protection calculation together with the matched local real-time sampling data. The application can store the sampling data of a longer time window in a fixed size buffer space, prolong the judgment time window of the differential protection, and improve the reliability and adaptability of the differential protection to the communication delay.

Description

Technical Field

[0001] This invention belongs to the field of power system relay protection technology, specifically relating to a differential protection method and system suitable for communication delay uncertainty. Background Technology

[0002] Traditional power system differential protection involves synchronizing the protection devices on both sides of the protection zone, then having the two protection devices transmit their respective collected sample values, including the sampling time, via optical fiber. After receiving the sample value from the other side, the protection device on its side selects the sample value with the same sampling time from its data buffer and uses these two sets of data to make differential protection judgments.

[0003] Currently, data transmission for differential protection is divided into wireless and wired methods. While fiber optic communication offers advantages such as low latency and no jitter, its high construction cost, maintenance difficulties, and low channel utilization severely limit its widespread application in differential protection systems. Wireless communication, on the other hand, boasts low construction costs, easy maintenance, and flexible expansion. 5G communication, as a next-generation wireless communication technology, provides a communication foundation for differential protection in distribution networks with its high bandwidth and low latency. It is already being applied to differential protection in distribution networks, offering new prospects for the precise location and isolation of faults in power system distribution networks.

[0004] However, both wired and wireless communication have the problem of time delay uncertainty in the channel. Differential protection has extremely strict requirements on the analog quantity delay time on both sides of the line. Under the uncertainty of transmission delay, when the sampling data of the differential device on the other side is sent to this side, the historical sampling data of this period has already been covered or discarded in the buffer of this device, resulting in the differential protection malfunctioning or refusing to operate, thus affecting the reliability of differential protection. Summary of the Invention

[0005] The purpose of this invention is to provide a differential protection method and system suitable for communication delay uncertainty, so as to solve the problem of reduced reliability caused by communication delay uncertainty when performing differential protection by communication.

[0006] To address the aforementioned technical problems, this invention provides a differential protection method suitable for communication delay uncertainty, comprising:

[0007] Step S1: The local differential protection device stores the real-time sampling data into different pre-defined data buffers according to their distance from the current sampling time.

[0008] Step S2: Receive real-time sampling data sent by the differential protection device on the other side through a communication channel with unknown time delay; match the real-time sampling data of the same sampling time from the data buffer of the differential protection device on this side according to the sampling time of the differential protection device on the other side; and calculate the extraction rate required for the real-time sampling data of the other side.

[0009] Step S3: Extract the received real-time sampling data from the other side according to the extraction rate, and then perform differential protection calculations on the extracted real-time sampling data from the other side and the matched real-time sampling data from the local side.

[0010] Furthermore, before step S1, the differential protection device on this side divides its own data cache space into multiple data cache areas of the same memory size and constructs them into a cache queue according to the first-in-first-out rule.

[0011] Furthermore, the sampling data of the differential protection device on this side is stored in the first buffer queue in real time according to the first-in-first-out rule. After the first buffer queue is full, the earliest sampled data in the buffer of this area overflows and is extracted and stored in the second buffer queue according to the preset extraction rate. After the second buffer queue is full, the earliest sampled data in the buffer of this area overflows and is extracted and stored in the third buffer queue according to the preset extraction rate. This process is repeated in a progressive and cyclical manner.

[0012] Further, step S2 specifically includes: the local differential protection device receives a message frame sent by the remote differential protection device through a communication channel with unknown delay, confirms the sampling time of the remote differential protection device based on the message frame, then matches the sampling data of the local differential protection device with the same sampling time from the data buffer of the local differential protection device, and calculates the extraction rate required for the data of the remote differential protection device.

[0013] Furthermore, the step of calculating the sampling rate required for the differential protection device data on the opposite side specifically involves selecting the sampling rate corresponding to the sampling time of the matched differential protection device data on this side as the sampling rate required for the differential protection device data on the opposite side.

[0014] The present invention also provides a differential protection system suitable for communication delay uncertainty, including a local differential protection device, a remote differential protection device, and a differential protection calculation module;

[0015] The local differential protection device is used to store real-time sampling data into different pre-divided data buffers according to their distance from the current sampling time; receive real-time sampling data sent by the opposite differential protection device through a communication channel with unknown time delay; match the local real-time sampling data with the same sampling time from the data buffer of the local differential protection device according to the sampling time of the opposite differential protection device; and calculate the extraction rate required for the real-time sampling data of the opposite side.

[0016] The differential protection calculation module is used to perform differential protection calculations by extracting the real-time sampling data of the opposite side according to the extraction rate and matching the real-time sampling data of the local side.

[0017] Furthermore, the local differential protection device divides its own data cache space into multiple data cache areas of the same memory size, and constructs them into a cache queue according to the first-in-first-out rule.

[0018] Furthermore, the sampling data of the differential protection device on this side is stored in the first buffer queue in real time according to the first-in-first-out rule. After the first buffer queue is full, the earliest sampled data in the buffer overflows and is extracted and stored in the second buffer queue according to the preset extraction rate. After the second buffer queue is full, the earliest sampled data in the buffer overflows and is extracted and stored in the third buffer queue according to the preset extraction rate. This process is repeated in a cyclical manner.

[0019] Furthermore, the local differential protection device receives a message frame sent by the remote differential protection device through a communication channel with unknown delay. Based on the message frame, it confirms the sampling time of the remote differential protection device, then matches the sampling data of the local differential protection device with the same sampling time from the data buffer of the local differential protection device, and calculates the extraction rate required for the data of the remote differential protection device.

[0020] Furthermore, the step of calculating the sampling rate required for the differential protection device data on the opposite side specifically involves selecting the sampling rate corresponding to the sampling time of the matched differential protection device data on this side as the sampling rate required for the differential protection device data on the opposite side.

[0021] The present invention has the following advantages: Compared with the traditional differential protection method, the present invention can store sampling data for a longer time window in a fixed-size buffer space, extend the time window for comparing the sampling values ​​of the two differential protection devices, and improve the reliability of differential protection. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating a differential protection method applicable to communication delay uncertainty according to an embodiment of the present invention.

[0024] Figure 2This is a schematic diagram illustrating the implementation principle of an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram illustrating the implementation of the progressive partitioning cache in this embodiment of the invention. Detailed Implementation

[0026] The following description of the embodiments is taken with reference to the accompanying drawings, which illustrate specific embodiments in which the invention can be implemented.

[0027] Please refer to Figure 1 As shown, Embodiment 1 of the present invention provides a differential protection method suitable for communication delay uncertainty, comprising:

[0028] Step S1: The local differential protection device stores the real-time sampling data into different pre-defined data buffers according to their distance from the current sampling time.

[0029] Step S2: Receive real-time sampling data sent by the differential protection device on the other side through a communication channel with unknown time delay; match the real-time sampling data of the same sampling time from the data buffer of the differential protection device on this side according to the sampling time of the differential protection device on the other side; and calculate the extraction rate required for the real-time sampling data of the other side.

[0030] Step S3: Extract the received real-time sampling data from the other side according to the extraction rate, and then perform differential protection calculations on the extracted real-time sampling data from the other side and the matched real-time sampling data from the local side.

[0031] Specifically, please combine Figure 2 , Figure 3 As shown, in this embodiment, the protected area consists of a local differential protection device and a remote differential protection device, with the two differential protection devices synchronizing in time. The local differential protection device pre-divides the data cache space into three data cache areas of equal memory size (e.g., ...). Figure 2 The data is stored in three buffer areas (A, B, and C) as shown, and arranged into buffer queues according to a first-in-first-out (FIFO) rule. The sampled data from the differential protection device on this side is stored in real-time in the first buffer queue (data buffer C area) using the FIFO rule. When the first buffer queue is full, the earliest sampled data in this area overflows and is extracted and stored in the second buffer queue (data buffer B area) at a 1 / 2 extraction rate. When the second buffer queue is full, the earliest sampled data in this area overflows and is extracted and stored in the third buffer queue (data buffer A area) at a 1 / 2 extraction rate. This progressive cyclic storage continues. This progressive partitioned caching method of the present invention avoids the problem of insufficient buffered sampled values ​​for differential protection calculations caused by the uncertainty of data transmission delays in wireless communication.

[0032] For example, the sampled values ​​of the differential protection device on this side are first stored in data buffer C. Assuming that data buffer C can cache a maximum of 4 sampled data, if data buffer C is full and more sampled data needs to be stored, the sampled data at time t1 in data buffer C (assuming the time order is t1-t2-t3-t4, with time t1 being the earliest) is stored in data buffer B at a sampling rate of 1 / 2; the sampled data at time t2 in data buffer C is stored in data buffer B at a sampling rate of 1 / 2; then, the sampled data at time t1 in data buffer B is stored in data buffer A at a sampling rate of 1 / 2, and the sampled data at time t3 in data buffer C is stored in data buffer B at a sampling rate of 1 / 2; then, the sampled data at time t2 in data buffer B is stored in data buffer A at a sampling rate of 1 / 2, and the sampled data at time t4 in data buffer C is stored in data buffer B at a sampling rate of 1 / 2; following this rule, the data buffers are subsequently partitioned and cached progressively.

[0033] In step S2, the local differential protection device receives a message frame sent by the remote differential protection device through a communication channel with unknown delay. Based on the message frame, it confirms the sampling time of the remote differential protection device. Then, it matches the sampling data of the local differential protection device with the same sampling time from its data buffer and calculates the required sampling rate for the remote differential protection device's data. It should be noted that calculating the required sampling rate for the remote differential protection device's data specifically involves selecting the sampling rate corresponding to the sampling time of the matched local differential protection device's sampling data as the required sampling rate for the remote differential protection device's data. The sampling rate can be selected based on actual conditions; the smaller the data buffer, the higher the selected sampling sampling rate.

[0034] In this embodiment, the differential protection device on the opposite side transmits real-time sampled data to the differential protection device on the local side through a communication channel with unknown time delay, and performs differential algorithm calculations with the sampled data in the progressive partition buffer of the differential protection device on the local side to realize differential protection.

[0035] Corresponding to the differential protection method applicable to communication delay uncertainty in Embodiment 1 of the present invention, Embodiment 2 of the present invention provides a differential protection system applicable to communication delay uncertainty, including a local differential protection device, a remote differential protection device, and a differential protection calculation module;

[0036] The local differential protection device is used to store real-time sampling data into different pre-divided data buffers according to their distance from the current sampling time; receive real-time sampling data sent by the opposite differential protection device through a communication channel with unknown time delay; match the local real-time sampling data with the same sampling time from the data buffer of the local differential protection device according to the sampling time of the opposite differential protection device; and calculate the extraction rate required for the real-time sampling data of the opposite side.

[0037] The differential protection calculation module is used to perform differential protection calculations by extracting the real-time sampling data of the opposite side according to the extraction rate and matching the real-time sampling data of the local side.

[0038] Furthermore, the local differential protection device divides its own data cache space into multiple data cache areas of the same memory size, and constructs them into a cache queue according to the first-in-first-out rule.

[0039] Furthermore, the sampling data of the differential protection device on this side is stored in the first buffer queue in real time according to the first-in-first-out rule. After the first buffer queue is full, the earliest sampled data in the buffer overflows and is extracted and stored in the second buffer queue according to the preset extraction rate. After the second buffer queue is full, the earliest sampled data in the buffer overflows and is extracted and stored in the third buffer queue according to the preset extraction rate. This process is repeated in a cyclical manner.

[0040] Furthermore, the local differential protection device receives a message frame sent by the remote differential protection device through a communication channel with unknown delay. Based on the message frame, it confirms the sampling time of the remote differential protection device, then matches the sampling data of the local differential protection device with the same sampling time from the data buffer of the local differential protection device, and calculates the extraction rate required for the data of the remote differential protection device.

[0041] Furthermore, the step of calculating the sampling rate required for the differential protection device data on the opposite side specifically involves selecting the sampling rate corresponding to the sampling time of the matched differential protection device data on this side as the sampling rate required for the differential protection device data on the opposite side.

[0042] For the working principle and process of the differential protection system applicable to communication delay uncertainty in this embodiment, please refer to the description of the aforementioned Embodiment 1 of the present invention, which will not be repeated here.

[0043] As can be seen from the above description, compared with the prior art, the beneficial effects of the present invention are as follows: compared with the traditional differential protection method, the present invention can store sampling data for a longer time window in a fixed-size buffer space, extend the time window for comparing the sampling values ​​of the two differential protection devices, and improve the reliability of differential protection.

[0044] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A differential protection method suitable for communication delay uncertainty, characterized in that, include: Step S1: The local differential protection device stores the real-time sampling data into different pre-defined data buffers according to their distance from the current sampling time. Specifically, the sampled data is stored in the first cache queue in real time according to the first-in-first-out rule. When the first cache queue is full, the earliest sampled data in the cache overflows and is extracted and stored in the second cache queue according to the preset extraction rate. When the second cache queue is full, the earliest sampled data in the cache overflows and is extracted and stored in the third cache queue according to the preset extraction rate. This process is repeated in a loop. Step S2: Receive real-time sampling data sent by the differential protection device on the other side through a communication channel with unknown time delay; match the real-time sampling data of the same sampling time from the data buffer of the differential protection device on this side according to the sampling time of the differential protection device on the other side; and calculate the extraction rate required for the real-time sampling data of the other side. Step S3: Extract the received real-time sampling data from the other side according to the extraction rate, and then perform differential protection calculations on the extracted real-time sampling data from the other side and the matched real-time sampling data from the local side.

2. The method according to claim 1, characterized in that, Before step S1, the differential protection device on this side divides its own data cache space into multiple data cache areas of the same memory size and constructs them into a cache queue according to the first-in-first-out rule.

3. The method according to claim 1, characterized in that, Step S2 specifically includes: the local differential protection device receives a message frame sent by the remote differential protection device through a communication channel with unknown delay; confirms the sampling time of the remote differential protection device based on the message frame; then matches the sampling data of the local differential protection device with the same sampling time from the data buffer of the local differential protection device; and calculates the extraction rate required for the data of the remote differential protection device.

4. The method according to claim 3, characterized in that, The extraction rate required for calculating the data of the differential protection device on the opposite side is specifically: based on the sampling time of the sampled data of the matched differential protection device on this side, the extraction rate corresponding to the sampling time is selected as the extraction rate required for the data of the differential protection device on the opposite side.

5. A differential protection system suitable for communication delay uncertainty, characterized in that, Includes the differential protection device on this side, the differential protection device on the opposite side, and the differential protection calculation module; The local differential protection device is used to store real-time sampling data into different pre-divided data buffers according to their distance from the current sampling time; receive real-time sampling data sent by the opposite differential protection device through a communication channel with unknown time delay; match the local real-time sampling data with the same sampling time from the data buffer of the local differential protection device according to the sampling time of the opposite differential protection device; and calculate the extraction rate required for the real-time sampling data of the opposite side. The differential protection calculation module is used to perform differential protection calculations on the real-time sampling data obtained by extracting the real-time sampling data of the opposite side according to the extraction rate and the matched real-time sampling data of the local side. The sampling data of the differential protection device on this side is stored in the first buffer queue in real time according to the first-in-first-out rule. When the first buffer queue is full, the earliest sampled data in the buffer overflows and is extracted and stored in the second buffer queue according to the preset extraction rate. When the second buffer queue is full, the earliest sampled data in the buffer overflows and is extracted and stored in the third buffer queue according to the preset extraction rate. This process is repeated in a cyclical manner.

6. The system according to claim 5, characterized in that, The differential protection device on this side divides its own data cache space into multiple data cache areas of the same memory size, and constructs them into a cache queue according to the first-in-first-out rule.

7. The system according to claim 5, characterized in that, The local differential protection device receives a message frame sent by the remote differential protection device through a communication channel with unknown delay. Based on the message frame, it confirms the sampling time of the remote differential protection device, then matches the sampling data of the local differential protection device with the same sampling time from the data buffer of the local differential protection device, and calculates the extraction rate required for the data of the remote differential protection device.

8. The system according to claim 7, characterized in that, The extraction rate required for calculating the data of the differential protection device on the opposite side is specifically: based on the sampling time of the sampled data of the matched differential protection device on this side, the extraction rate corresponding to the sampling time is selected as the extraction rate required for the data of the differential protection device on the opposite side.

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