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

Abstract

The invention discloses a segmented power supply AT traction network protection scheme and system based on correlation analysis, and belongs to the technical field of railway traction network relay protection. Firstly, voltage data and current data on the two sides 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 a protection scheme, and correlation coefficients of currents on the two sides of each section are calculated; and finally, constructing a fault identification criterion according to the correlation coefficients of the currents at the two sides of each section, disconnecting circuit breakers at the two sides and isolating the fault in the section meeting the fault identification criterion, and continuously collecting data in real time in the section not meeting the fault identification criterion. The protection scheme provided by the invention is simple and reliable in algorithm and good in quickness, the time from fault occurrence to tripping signal sending is about 150ms, the fault section of the subsection power supply AT traction network can be quickly cut off, normal power supply of the traction network in the non-fault section is ensured, the power failure range is reduced, and the requirements of protection selectivity and quickness of the subsection power supply AT traction network are met.

Description

Technical Field

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

[0002] With the development of my country's high-speed railways, the full parallel AT power supply wiring method has been widely used in traction power supply systems due to its high power supply power and high power supply reliability. Considering the complex wiring form of the full parallel AT traction power supply method, it is crucial to configure an accurate and reliable protection scheme to ensure the safe operation of high-speed railways. In the existing protection scheme, when a fault occurs at any position of the power supply arm, the traction substation circuit breaker will trip, causing the entire power supply arm to lose power. Especially for the full parallel AT power supply traction network, after a fault occurs, both the upstream power supply arm and the downstream power supply arm will lose power, and the power outage range will be larger.

[0003] To solve this problem, some scholars have proposed a method of segmented power supply for the traction network, which divides the full parallel AT traction network into several sections, and uses the currents on both sides of the segmented sections to construct a differential current, which is compared with the set value to determine whether the section 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, and has 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 reduce the scope of power outage to the maximum extent and ensure normal power supply to non-fault sections. Summary of the invention

[0005] The purpose of the present invention is to solve the protection problem of the segmented power supply AT traction network and provide a segmented power supply AT traction network protection solution and system based on correlation analysis, which can accurately and timely reduce the scope of power outage to the maximum extent and ensure normal power supply to non-fault sections.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following scheme: first, the voltage data 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 starting criterion of the protection scheme, and after the starting criterion is met, the correlation coefficient of the current on both sides of each section is calculated; finally, a fault identification criterion is constructed according to the correlation coefficient of the current on both sides of each section, and for the sections that meet the fault identification criterion, the circuit breakers on both sides are disconnected to isolate the fault; for the sections that do not meet the fault identification criterion, real-time data collection continues.

[0007] On the one hand, the present invention provides a protection scheme for a segmented power supply AT traction network based on correlation analysis, which specifically includes: 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, , indicating the segmented power supply section of the full parallel AT traction network; Step 2: Construct low voltage start criteria based on the voltages on both sides of each section; Step 3: If the low voltage start criterion is met, calculate the correlation coefficient of the current on both sides of each section; if the low voltage start criterion is not met, continue to execute Step 1; Step 4: Construct fault identification criteria based on the current correlation coefficients on both sides of each section; Step 5: For the sections that meet the fault identification criteria, disconnect the circuit breakers on both sides to isolate the fault; for the sections that do not meet the fault identification criteria, continue to execute Step 1.

[0008] Furthermore, in Step 1, each section of the segmented power supply AT traction network is equipped with a local measurement and control unit. ,in, , indicating the full parallel AT traction network segmented power supply section; the local measurement and control unit For processing and analyzing segments Current data and voltage data, and for the segment The circuit breakers on both sides are controlled; the measurement and control system They are dispersedly arranged in traction substations, AT stations and substations to form distributed unit protection units.

[0009] Furthermore, in Step 2, the low voltage startup criterion is: , where For segment The voltage on the left side, For segment The voltage on the right side, It is the low voltage protection setting value.

[0010] Furthermore, in Step 3, Pearson correlation is used to quantify the segments. Current on both sides and The correlation coefficient of each segment The calculation formula is as follows:

[0011] .

[0012] Furthermore, in Step 4, the fault identification criterion is: .

[0013] Another aspect of the present invention provides a segmented power supply AT traction network protection system based on correlation analysis, specifically comprising: Data acquisition module: collects voltage and current data at both ends of each section of the sectional power supply AT traction network in real time, and converts the collected 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 set value, calculates the current correlation coefficient on both sides of each section and compares it with the set value, and determines whether each section is faulty based on the calculation results; Circuit breaker control module: Open the circuit breaker or keep the circuit breaker closed according to the results provided by the data processing module.

[0014] The beneficial effects of the present invention are: 1. Compared with the traditional set value protection, the present 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 and does not need to be set according to the actual use scenario, so it has a wide range of applications. 2. The protection scheme algorithm proposed in the present invention is simple, reliable and has good speed. The time from the occurrence of a fault to the issuance of a trip signal is about 150ms. Compared with traditional power frequency quantity protection, it has better selectivity and speed. 3. The present invention adopts a distributed protection solution, which eliminates the need to upload data to the substation main station, avoids data packet loss caused by communication channel congestion, and has high reliability.

[0015] In summary, the present invention constructs a scheme and system for a segmented power supply AT traction network based on correlation analysis, isolates the faulty section promptly and accurately, minimizes the scope of power outage, improves the power supply reliability of the traction network, and ensures the safe operation of the high-speed railway. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to better understand the above technical scheme, 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 accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art, and the accompanying drawings of the present invention are as follows.

[0017] Figure 1 This is a structural diagram of the segmented power supply AT traction network of the present invention.

[0018] Figure 2 This is a flow chart of the protection scheme for the segmented power supply AT traction network of the present invention.

[0019] Figure 3 This is a module block diagram of the segmented power supply AT traction network protection system of the present invention.

[0020] Figure 4The voltage waveform and effective value on both sides of the section where the locomotive passes in Example 1 of the present invention.

[0021] Figure 5 1 is a voltage waveform diagram and effective value on both sides of the fault section in Example 1 of the present invention.

[0022] Figure 6 1 is a current waveform diagram at the beginning and end of sections 1, 2, 3, and 4 in Example 2 of the present invention.

[0023] Figure 7 1 is a current waveform diagram at the beginning and end of sections 5, 6, 7, and 8 in Example 2 of the present invention.

[0024] Figure 8 1 is a current waveform diagram at the beginning and end of sections 9, 10, 11, and 12 in Example 2 of the present invention.

[0025] Fig. 9 1 is a current waveform diagram at the beginning and end of sections 1, 2, 3, and 4 in embodiment 3 of the present invention.

[0026] Fig.10 1 is a current waveform diagram at the beginning and end of sections 5, 6, 7, and 8 in Example 3 of the present invention.

[0027] Fig.11 1 is a current waveform diagram at the beginning and end of sections 9, 10, 11, and 12 in Example 3 of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The purpose of the present invention is to provide a protection scheme and system for a segmented power supply AT traction network based on correlation analysis, aiming to accurately and timely discover faults, and minimize the power outage scope of the segmented power supply AT power supply traction network, ensure normal power supply to non-faulty sections, and ensure the safe operation of high-speed railways. The present invention is further described below in conjunction with specific implementation methods.

[0030] Embodiment 1: This embodiment describes the low voltage startup criteria. Figure 1 As shown in the structural diagram, a segmented power supply AT traction network simulation model is built in the PSCAD / EMTDC electromagnetic transient simulation software. The traction system consists of a traction substation, two AT stations and a substation. The length of each power supply section is 10km, the data sampling frequency is 100kHz, and the low voltage starting setting value is Set to 18kV.

[0031] In the model, two situations are set: the locomotive passes through section 2 and the contact network of section 2 has a ground fault. The fault time is 0.27s. The voltage waveforms and their effective values ​​on both sides of section 2 are as follows: Figure 4 and Figure 5 shown.

[0032] Depend on Figure 4 and Figure 5 It can be seen that: when working normally or when a locomotive passes by, the voltage value on both sides of the section is greater than the protection setting value of this scheme, and 15ms after the fault occurs, the voltage value on both sides of the section is less than the low voltage protection setting value of this scheme, and the protection is activated. In summary, the low voltage startup criterion of the present invention can be reliably inactive when the voltage fluctuates normally and when a locomotive passes by; it can be reliably activated when a fault occurs.

[0033] Example 2: This example describes the fault identification criteria. In the PSCAD / EMTDC electromagnetic transient simulation model, it is set that a ground fault occurs in section 2 at 0.27s. The voltages of each section meet the low voltage start criteria, and the protection is started. The current data on both sides of each section within 0.1s after the fault is detected is recorded. Figure 6 , Figure 7 and Figure 8 As shown; calculate the Pearson correlation coefficient of the current on both sides of each segment: , , , , , , , , , , , .

[0034] It can be seen from this that the correlation coefficient of the current on both sides of section 2 is 0.99, which is greater than 0.6, and it is judged 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, and it is judged that there is no fault; therefore, the measurement and control unit of section 2 sends a tripping signal, disconnects the circuit breakers on both sides of section 2, and isolates the fault.

[0035] Example 3: This example describes the fault identification criteria. In the PSCAD / EMTDC electromagnetic transient simulation model, a ground fault is set in section 9. After each section is started by low voltage protection, the current data on both sides of each section within 0.1s after the fault is detected is recorded. Fig. 9 , Fig.10 and Fig.11 As shown; calculate the Pearson correlation coefficient of the current on both sides of each segment: , , , , , , , , , , , .

[0036] 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, and it is judged 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, and it is judged that there is no fault; therefore, the circuit breakers on both sides of section 9 are disconnected to isolate the fault.

[0037] In summary, the low voltage criterion of the present invention can reliably identify the situations in which the segmented power supply AT traction network is not faulty, the locomotive passes and is faulty. The fault identification criterion of the present invention can isolate the faulty section in a timely and accurate manner, minimize the scope of power outage, improve the power supply reliability of the traction network, and ensure the safe operation of the high-speed railway.

[0038] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A protection scheme for a segmented power supply AT traction network based on correlation analysis, characterized in that: 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, , indicating the AT traction network segmented power supply section; Step 2: Construct low voltage start criteria based on the voltages on both sides of each section; Step 3: If the low voltage start criterion is met, calculate the correlation coefficient of the current on both sides of each section; if the low voltage start criterion is not met, continue to execute Step 1; Step 4: Construct fault identification criteria based on the current correlation coefficients on both sides of each section; Step 5: For the sections that meet the fault identification criteria, disconnect the circuit breakers on both sides to isolate the fault; for the sections that do not meet the fault identification criteria, continue to execute Step 1.

2. According to the correlation analysis-based protection scheme for segmented power supply AT traction network according to claim 1, it is characterized by: In the Step 1, each section of the segmented power supply AT traction network is equipped with a local measurement and control unit. ,in, , indicating the AT traction network segmented power supply section; the local measurement and control unit For processing and analyzing segments Current data and voltage data, and for the segment The circuit breakers on both sides are controlled; the measurement and control system They are dispersedly arranged in traction substations, AT stations and substations to form distributed unit protection.

3. According to the correlation analysis-based protection scheme for segmented power supply AT traction network of claim 1, it is characterized by: In Step 2, the low voltage startup criterion is: , where For segment The voltage on the left side, For segment The voltage on the right side, It is the low voltage protection setting value.

4. According to the correlation analysis-based protection scheme for segmented power supply AT traction network of claim 1, it is characterized by: In Step 3, Pearson correlation is used to quantify the segments. Current on both sides and The correlation coefficient of each segment The calculation formula is as follows: 。 5. According to the correlation analysis-based protection scheme for segmented power supply AT traction network of claim 1, it is characterized by: In Step 4, the fault identification criterion is: .

6. A segmented power supply AT traction network protection system based on correlation analysis, characterized in that Implementing a segmented power supply AT traction network protection solution based on correlation analysis as described in any one of claims 1 to 5, comprising: Data acquisition module: collects voltage and current data on both sides of each section of the sectional power supply AT traction network in real time, and converts the collected 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 set value, calculates the current correlation coefficient on both sides of each section and compares it with the set value, and determines whether each section is faulty based on the calculation results; Circuit breaker control module: Open the circuit breaker or keep the circuit breaker closed according to the results provided by the data processing module.

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