Segmented power supply at traction network protection scheme and system based on correlation analysis

Abstract

The application discloses a segmented power supply AT traction network protection scheme and system based on correlation analysis, and belongs to the technical field of relay protection of railway traction network. Firstly, voltage data and current data of each section of the segmented power supply AT traction network are collected in real time; then, low-voltage protection is used as a starting criterion of the protection scheme to calculate correlation coefficients of currents on both sides of each section; finally, a fault identification criterion is constructed according to the correlation coefficients of the currents on both sides of each section, the section meeting the fault identification criterion is disconnected from circuit breakers on both sides to isolate the fault, and the section not meeting the fault identification criterion continues to collect data in real time. The protection scheme algorithm is simple, reliable and fast, the time from fault occurrence to sending a trip signal is about 150 ms, the fault section of the segmented power supply AT traction network can be quickly removed, normal power supply of the traction network in the non-fault section is ensured, the power cut range is reduced, and the requirements of selectivity and fast action of the segmented power supply AT traction network protection are met.

Description

Technical Field

[0001] This invention relates to a segmented power supply AT traction network protection scheme and system based on correlation analysis, belonging to the field of railway traction network relay protection technology. Background Technology

[0002] With the development of high-speed railways in my country, the fully parallel AT power supply wiring method has been widely used in traction power supply systems due to its advantages of high power supply capacity and high reliability. Considering the complexity of the wiring configuration of the fully parallel AT traction power supply method, configuring an accurate and reliable protection scheme is crucial for ensuring the safe operation of high-speed railways. Existing protection schemes will cause the traction substation circuit breaker to trip and the entire power supply arm to lose power if a fault occurs at any point on the power supply arm. This is especially true for fully parallel AT power supply traction networks, where both the upstream and downstream power supply arms will lose power after a fault, resulting in a wider power outage area.

[0003] To address this issue, some scholars have proposed a segmented power supply method for the traction network. This method divides the fully parallel AT traction network into several segments and uses the currents on both sides of each segment to construct a differential current, which is then compared with the set value to determine whether a segment is faulty. However, the protection scheme based on the set value is affected by the contact network capacitance, the transformer transmission characteristics, and the fault transition resistance, resulting in poor reliability.

[0004] Therefore, it is necessary to further study the protection scheme of the segmented power supply AT traction network in order to accurately and timely minimize the scope of power outages and ensure normal power supply to non-faulty sections. Summary of the Invention

[0005] The purpose of this invention is to solve the protection problem of segmented power supply AT traction network, and to provide a segmented power supply AT traction network protection scheme and system based on correlation analysis, which can accurately and timely minimize the power outage range and ensure normal power supply to non-faulty sections.

[0006] To achieve the above objectives, the present invention adopts the following scheme: First, voltage and current data on both sides of each section of the segmented power supply AT traction network are collected in real time; then, low voltage protection is used as the activation criterion for the protection scheme. After the activation criterion is met, the correlation coefficient of the current on both sides of each section is calculated; finally, a fault identification criterion is constructed based on the correlation coefficient of the current on both sides of each section. For sections that meet the fault identification criterion, the circuit breakers on both sides are disconnected to isolate the fault; for sections that do not meet the fault identification criterion, data collection continues in real time.

[0007] This invention provides a segmented power supply AT traction network protection scheme based on correlation analysis, specifically including:

[0008] Step 1: Real-time collection of voltage data on both sides of each section of the segmented power supply AT traction network. and current data And calculate its effective value in real time. ,in, This indicates a segmented power supply section of the fully parallel AT traction network;

[0009] Step 2: Construct low-voltage start-up criteria based on the voltage on both sides of each section;

[0010] Step 3: If the low-voltage start-up criterion is met, calculate the correlation coefficient of the current on both sides of each section; if the low-voltage start-up criterion is not met, continue to Step 1.

[0011] Step 4: Construct fault identification criteria based on the correlation coefficient of the current on both sides of each section;

[0012] Step 5: For sections that meet the fault identification criteria, disconnect the circuit breakers on both sides to isolate the fault; for sections that do not meet the fault identification criteria, continue to Step 1.

[0013] Furthermore, in Step 1, local monitoring and control units are set up in each section of the segmented power supply AT traction network. ,in, This indicates a segmented power supply section of the fully parallel AT traction network; the local measurement and control unit Used for processing and analyzing sections Current and voltage data, and for sections The control system is controlled by circuit breakers on both sides; They are distributed in traction substations, AT stations, and sectioning stations, forming distributed unit protection units.

[0014] Furthermore, in Step 2, the low-voltage start-up criterion is: In the formula, For section The voltage on the left side, For section The voltage on the right side, This is the undervoltage protection setting value.

[0015] Furthermore, in Step 3, Pearson correlation quantification is used for the segment. Current on both sides and The correlation between the segments and the correlation coefficients of each segment. The calculation formula is as follows:

[0016] .

[0017] Furthermore, in Step 4, the fault identification criterion is: .

[0018] Another aspect of the present invention provides a segmented power supply AT traction network protection system based on correlation analysis, specifically comprising:

[0019] Data acquisition module: Real-time acquisition of voltage and current data at both ends of each section of the segmented power supply AT traction network, and conversion of the acquired analog signals into digital signals;

[0020] Data processing module: Calculates the effective value of the voltage on both sides of each section and compares it with the setting value; calculates the correlation coefficient of the current on both sides of each section and compares it with the setting value; and determines whether each section is faulty based on the calculation results.

[0021] Circuit breaker control module: Based on the results provided by the data processing module, disconnect the circuit breaker or keep the circuit breaker closed.

[0022] The beneficial effects of this invention are:

[0023] 1. Compared with traditional setting value protection, this invention uses the Pearson correlation coefficient to characterize the difference in current on both sides of the section and constructs a protection criterion. The criterion setting value is a theoretical value, which does not need to be set according to the actual use scenario and has a wide range of applications.

[0024] 2. The protection scheme proposed in this invention has a simple, reliable algorithm and good speed. The time from the occurrence of the fault to the issuance of the trip signal is about 150ms. Compared with traditional power frequency quantity protection, it has better selectivity and speed.

[0025] 3. This invention adopts a distributed protection scheme, which eliminates the need to upload data to the substation's main station, avoiding data packet loss caused by communication channel congestion, and ensuring high reliability.

[0026] In summary, the present invention provides a scheme and system for constructing a segmented power supply AT traction network based on correlation analysis. This system can promptly and accurately isolate faulty sections, minimize the scope of power outages, improve the power supply reliability of the traction network, and ensure the safe operation of high-speed railways. Attached Figure Description

[0027] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art, as shown in the accompanying drawings below.

[0028] Figure 1 This is a structural diagram of the segmented power supply AT traction network of the present invention.

[0029] Figure 2This is a flowchart of the segmented power supply AT traction network protection scheme of the present invention.

[0030] Figure 3 This is a block diagram of the segmented power supply AT traction network protection system of the present invention.

[0031] Figure 4 The diagram shows the voltage waveforms and effective values ​​on both sides of the section through which the locomotive passes in Embodiment 1 of the present invention.

[0032] Figure 5 The diagram shows the voltage waveforms and RMS values ​​on both sides of the fault section in Embodiment 1 of the present invention.

[0033] Figure 6 This is a current waveform diagram of the beginning and end of segments 1, 2, 3, and 4 in Embodiment 2 of the present invention.

[0034] Figure 7 The current waveforms at the beginning and end of segments 5, 6, 7, and 8 in Embodiment 2 of the present invention are shown.

[0035] Figure 8 The current waveforms at the beginning and end of segments 9, 10, 11, and 12 in Embodiment 2 of the present invention are shown.

[0036] Figure 9 This is a current waveform diagram of the beginning and end of segments 1, 2, 3, and 4 in Embodiment 3 of the present invention.

[0037] Figure 10 The current waveforms at the beginning and end of segments 5, 6, 7, and 8 in Embodiment 3 of the present invention are shown.

[0038] Figure 11 The current waveforms at the beginning and end of segments 9, 10, 11, and 12 in Embodiment 3 of the present invention are shown. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The purpose of this invention is to provide a segmented power supply AT traction network protection scheme and system based on correlation analysis. This scheme aims to accurately and promptly detect faults, minimize the power outage range of the segmented power supply AT traction network, ensure normal power supply to non-faulty sections, and guarantee the safe operation of high-speed railways. The invention will be further described below with reference to specific embodiments.

[0041] Example 1: This example explains the low-voltage start-up criterion, according to... Figure 1 The structural diagram shown illustrates a segmented power supply AT traction network simulation model built in PSCAD / EMTDC electromagnetic transient simulation software. This traction system consists of one traction substation, two AT substations, and one section substation. Each power supply segment is 10km long, the data sampling frequency is 100kHz, and the low-voltage start-up setting value is... Set to 18kV.

[0042] The model includes two scenarios: the locomotive passing through section 2 and a ground fault occurring in the contact network of section 2. The fault time is 0.27 seconds. The voltage waveforms and their effective values ​​on both sides of section 2 are shown below. Figure 4 and Figure 5 As shown.

[0043] Depend on Figure 4 and Figure 5 It can be seen that during normal operation or when a locomotive passes by, the voltage values ​​on both sides of the section are greater than the protection setting value of this scheme. 15ms after a fault occurs, the voltage values ​​on both sides of the section are less than the low-voltage protection setting value of this scheme, and the protection is activated. In summary, the low-voltage activation criterion of this invention can reliably not operate during normal voltage fluctuations and when a locomotive passes by; it can reliably operate when a fault occurs.

[0044] Example 2: This example illustrates the fault identification criteria. In the PSCAD / EMTDC electromagnetic transient simulation model, a ground fault is set in section 2 at 0.27s. The voltage of each section meets the low-voltage start-up criterion, the protection is activated, and the current data on both sides of each section within 0.1s after the fault is detected are recorded. Figure 6 , Figure 7 and Figure 8 As shown; calculate the Pearson correlation coefficient of the current on both sides of each section: , , , , , , , , , , , .

[0045] It can be seen that the correlation coefficient of the current on both sides of section 2 is 0.99, which is greater than 0.6, indicating that there is a fault in the section; the correlation coefficient of the current on both sides of other sections is less than 0.6, indicating that there is no fault. Therefore, the measurement and control unit of section 2 sends a trip signal to disconnect the circuit breakers on both sides of section 2 and isolate the fault.

[0046] Example 3: This example illustrates the fault identification criteria. In the PSCAD / EMTDC electromagnetic transient simulation model, a ground fault is set in section 9. After each section is activated by low-voltage protection, the current data on both sides of each section within 0.1 seconds after the fault is detected is recorded. Figure 9 , Figure 10 and Figure 11 As shown; calculate the Pearson correlation coefficient of the current on both sides of each section: , , , , , , , , , , , .

[0047] It can be seen that the correlation coefficient of the current on both sides of section 9 is 0.98, which is greater than 0.6, indicating that there is a fault in the section; the correlation coefficients of the current on both sides of other sections are all less than 0.6, indicating that there is no fault; therefore, the circuit breakers on both sides of section 9 are disconnected to isolate the fault.

[0048] In summary, the low voltage criterion of this invention can reliably identify whether the segmented power supply AT traction network is fault-free, has a locomotive passing by, or is faulty. The fault identification criterion of this invention can promptly and accurately isolate the faulty section, minimize the power outage range, improve the power supply reliability of the traction network, and ensure the safe operation of high-speed railways.

[0049] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A segmented power supply AT traction network protection method based on correlation analysis, characterized in that: Step 1: Set up local monitoring and control units in each section of the segmented power supply AT traction network. The local measurement and control unit collects voltage data from both sides of each section of the segmented power supply AT traction network in real time. and current data Real-time calculation of voltage RMS value and for the section The circuit breakers on both sides are used for control, among which, This indicates the segmented power supply section of the AT traction network; Step 2: Construct a low-voltage start-up criterion based on the voltage on both sides of each section. The low-voltage start-up criterion is as follows: In the formula, For section The voltage on the left side, For section The voltage on the right side, This is the undervoltage protection setting value; Step 3: If the low-voltage start-up criterion is met, extract the current sampling data on both sides of each segment within a transient time window of no more than 100ms after low-voltage start-up, and calculate the current on both sides of each segment based on the current data within the time window. and correlation coefficient The correlation coefficient mentioned is the Pearson correlation coefficient, and the calculation formula is as follows: ； If the low voltage start-up criterion is not met, continue to collect voltage and current data on both sides of each section of the segmented power supply AT traction network in real time. Step 4: Construct fault identification criteria based on the correlation coefficient of the currents on both sides of each section. The fault identification criteria are as follows: ; Step 5: For sections that meet the fault identification criteria, disconnect the circuit breakers on both sides to isolate the fault; for sections that do not meet the fault identification criteria, continue to collect voltage and current data on both sides of each section of the segmented power supply AT traction network in real time.

2. A segmented power supply AT traction network protection system based on correlation analysis, characterized in that... Implementing the segmented power supply AT traction network protection method based on correlation analysis as described in claim 1, comprising: Data acquisition module: Real-time acquisition of voltage and current data on both sides of each section of the segmented power supply AT traction network, and conversion of the acquired analog signals into digital signals; Data processing module: Calculates the effective value of the voltage on both sides of each section and compares it with the setting value; calculates the correlation coefficient of the current on both sides of each section and compares it with the setting value; and determines whether each section is faulty based on the calculation results. Circuit breaker control module: Based on the results provided by the data processing module, disconnect the circuit breaker or keep the circuit breaker closed.

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