A flooding type sampling synchronization method suitable for differential protection of power distribution network system

Abstract

The application provides a flooding type sampling synchronization method suitable for differential protection of power distribution network system, any one power distribution automation device with differential protection function in a line is set as a host computer, and the rest are set as slave computers; the host computer uses a calculation period data frame to flood and publish the latched value of the sampling count value of the PPS second pulse moment of GPS / BD to adjacent devices; the adjacent devices flood and send the received information to their adjacent devices in turn at intervals of the calculation period, so that all power distribution automation terminals know the latched value of the sampling point count of the host computer second pulse moment. The application realizes the unity of the sampling point count of all line power distribution automation terminals by using a simple flooding method, thereby ensuring the unity of the calculation moment, well meeting the demand of the differential protection of the power distribution network, and having a smaller demand for calculation amount, and being implemented with a smaller change on the basis of the original power distribution automation equipment design.

Description

Technical Field

[0001] This invention relates to the field of power system distribution network protection technology, and specifically provides a flooding sampling synchronization method suitable for differential protection of distribution network systems. Background Technology

[0002] With the grid connection of a large number of distributed power sources, the distribution network has gradually evolved into a multi-source power supply network architecture. The increased penetration rate of distributed power sources may make it difficult to set the three-stage overcurrent protection settings, and in extreme cases, it may even cause the overcurrent protection function to fail.

[0003] Differential protection has inherent selectivity, making it highly suitable for multi-source networks. Due to the relatively low voltage levels in distribution networks and the high cost control requirements of automation equipment, the best way to implement differential functionality is to add differential functionality to existing distribution automation devices. For example... Figure 1 As shown, the device located between two nodes (e.g., 0802) needs to participate in the dual-end or multi-end differential protection on both sides. If the cost is increased by adding more devices or by calculating independently on both sides, it will increase the cost. Summary of the Invention

[0004] The technical objective of this invention is to address the aforementioned problems by providing a flooding-type sampling synchronization method suitable for differential protection in distribution network systems. This method achieves the sampling synchronization requirements of relevant equipment at each differential node while meeting cost control requirements and without increasing CPU computational load.

[0005] A flood-type sampling synchronization method suitable for differential protection in a distribution network system is disclosed. Each segment of the distribution network system is equipped with a distribution automation device with differential protection function. The implementation of the flood-type sampling synchronization method includes the following:

[0006] Designate any one of the distribution automation devices with differential protection function in the line as the master (e.g., 0102), and the rest as slave devices;

[0007] The host uses the calculation periodic data frame to flood and publish the latched value of the sampled count value of the PPS second pulse of GPS / BD to adjacent devices;

[0008] The adjacent devices sequentially flood the received information to their respective adjacent devices at calculation intervals, so that all power distribution automation terminals know the sampling point count latch value at the second pulse moment of the host.

[0009] Furthermore, the differential protection function is a differential protection function installed in the distribution automation device of the 10kV distribution network system.

[0010] Furthermore, the calculation period is half a cycle, and the sampling points per cycle are 256 points. Specifically, the sampling calculation time is 0 or 128 points. The main content of the data frame is the fundamental current phasor value obtained from the full-wave data.

[0011] Furthermore, the method is implemented by setting an effective flooding time window to avoid flooding overlap and ensure that the counting at the sampling time is synchronized and effective;

[0012] Furthermore, the effective time window begins no earlier than 30ms after the PPS second pulse and ends no later than 150ms.

[0013] Furthermore, after the effective time for flood transmission ends, the host calculates the periodic data frame and clears the flood valid bit.

[0014] Furthermore, two additional distribution automation devices with differential protection functions located at the same-name protection node and different-name protection nodes of the main unit are used as backup main units.

[0015] Furthermore, the backup host is activated when no host information is received for more than 3 seconds;

[0016] Once the host computer resumes communication, the backup host computer begins to re-forward the host computer's latched data.

[0017] Furthermore, when the slave device receives information directly or through flooding from the master device, it performs a difference calculation between the latched value of the master device's sampled count and its own latched value of the PPS second pulse moment. When the difference between the sampling points is greater than 2 points, the counting point is adjusted to 8 or 12 points when sampling at the 10th point of each cycle. By jumping forward or backward, the calculation time (0 or 128 points) is cleverly avoided to achieve a smooth transition of the calculated value.

[0018] Furthermore, when the difference between the sampling points exceeds 8 points, the differential protection function is locked.

[0019] Compared with existing technologies, the flooding sampling synchronization method for differential protection of distribution network systems proposed in this invention has the following outstanding advantages:

[0020] This invention utilizes a simple flooding method to unify the counting of sampling points at the entire distribution automation terminal, thereby ensuring consistent calculation timing. This effectively meets the needs of differential protection in distribution networks, while requiring relatively low computational load. It can be implemented with minor modifications to the existing distribution automation equipment design. It achieves the sampling synchronization requirements of related equipment at each differential node without increasing CPU computational load, while simultaneously meeting cost control requirements. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a typical circuit topology of a power distribution network;

[0022] Figure 2 This is a diagram illustrating the flooding of host synchronization information. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0024] A flood-type sampling synchronization method applicable to differential protection of distribution network systems.

[0025] like Figure 1 As shown, a multi-dimensional self-sensing intelligent pole-mounted switch designates any one of the distribution automation devices 0102 with differential protection function in the circuit as the master, and designates two other devices 0207 and 0103 located at the same-name protection node and different-name protection node of the master as backup masters.

[0026] The latched value and flooding of the sampled count value of the PPS second pulse moment of GPS / BD are effectively published to adjacent devices by using the calculation periodic data frame;

[0027] When the slave device receives information directly from the master device or after flooding, it calculates the difference between the latched value of the master device's sample count and its own latched value at the PPS second pulse moment. When the difference between the sampling points is greater than 2 points, it adjusts the counting point to 8 or 12 points at the 10th point of each cycle, cleverly avoiding the calculation time (0 or 128 points) by jumping forward or backward to achieve a smooth transition of the calculated value. When the difference between the sampling points exceeds 8 points, the differential protection function is locked.

[0028] like Figure 2 As shown, adjacent devices sequentially send this information to their respective neighbors at intervals based on the calculation cycle, enabling all distribution automation terminals to obtain the sampling point count latch value at the second pulse moment of the host. This fulfills the sampling synchronization requirements of related devices at each differential node.

[0029] To avoid overlapping flooding, an effective flooding time window is set to ensure that the counting at the sampling time is synchronized and effective;

[0030] The effective time window begins no earlier than 35ms after the PPS second pulse and ends at 135ms. After the effective time window ends, the host calculates the periodic data frame and clears the flooded valid bits.

[0031] If the backup host does not receive host information for more than 3 seconds, it will be activated; when the host resumes communication, the backup host will start to re-forward the host latched data.

[0032] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solutions of the present invention should be included within the protection scope of the present invention.

Claims

1. A flood-type sampling synchronization method suitable for differential protection in distribution network systems, characterized in that, Each segment of the power distribution network system is equipped with a distribution automation device with differential protection function. The implementation of the flooding sampling synchronization method includes the following: Set any one of the distribution automation devices with differential protection function in the line as the master, and set the rest of the devices as slaves; The host uses the calculation periodic data frame to flood and publish the latched value of the sampled count value of the PPS second pulse of GPS / BD to adjacent devices. The adjacent devices sequentially flood the received information to their respective adjacent devices at calculation intervals, so that all power distribution automation terminals know the sampling point count latch value at the second pulse moment of the host. The calculation period is half a cycle, the sampling points are 256 points per cycle, and the sampling calculation time is 0 or 128 points. The main content of the data frame is the fundamental current phasor value obtained from the full-wave data. When the slave device receives information directly or through flooding from the master device, it performs a difference calculation between the latched value of the master device's sampled count and its own latched value of the PPS second pulse. When the difference between the sampling points is greater than 2 points, the counting point is adjusted to 8 or 12 points when sampling at the 10th point of each cycle. By jumping forward or backward, the counting point is cleverly avoided at the calculation time of 0 or 128 points to achieve a smooth transition of the calculated value.

2. The flooding sampling synchronization method for differential protection of distribution network systems according to claim 1, characterized in that, The differential protection function is a differential protection function installed in the distribution automation device of the 10kV distribution network system.

3. The flooding sampling synchronization method for differential protection of distribution network systems according to claim 1, characterized in that, The method is implemented by setting an effective flooding time window to avoid flooding overlap and ensure that the sampling time count is synchronized and effective.

4. The flooding sampling synchronization method for differential protection of distribution network systems according to claim 3, characterized in that, The effective time window starts no earlier than 30ms after the PPS second pulse and ends no later than 150ms.

5. The flooding sampling synchronization method for differential protection of distribution network systems according to claim 4, characterized in that, After the effective time window expires, the host uses the calculation cycle data frame to clear the flooding valid bits.

6. The flooding sampling synchronization method for differential protection of distribution network systems according to claim 1, characterized in that, The implementation of the method also includes: Two other power distribution automation devices with differential protection functions, located at the same-name protection node and the different-name protection node of the main unit, are used as backup main units.

7. A flooding-type sampling synchronization method for differential protection of distribution network systems according to claim 6, characterized in that, The backup host is activated when no host information is received for more than 3 seconds. Once the host computer resumes communication, the backup host computer begins to re-forward the host computer's latched data.

8. A flooding sampling synchronization method for differential protection in a distribution network system according to claim 7, characterized in that, When the difference between the sampling points exceeds 8 points, the differential protection function is locked.

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