A method for relay protection of contact network in a through-type in-phase power supply system

Abstract

This invention discloses a method for contact network relay protection in a through-type in-phase power supply system. The method determines when the contact network voltage drops while the current exceeds a threshold setting, thus entering a protection processing state. It analyzes the system using the up and down feeders within the same section as units, fully considering various fully continuous operating conditions. By comparing the current magnitudes of the two feeders, different protection action delays are selected to complete the contact network relay protection. This ensures the selectivity of the contact network relay protection in the through-type in-phase power supply system, narrows the power outage range, and provides stronger selectivity and speed, offering a valid basis for future contact network protection in in-phase power supply systems.

Description

Technical Field

[0001] This invention belongs to the field of relay protection for traction power supply systems, and in particular relates to a relay protection method for contact network of a through-type in-phase power supply system. Background Technology

[0002] The traction power supply system is a core component of electrified railways and a crucial power source for electric locomotives. Currently, it commonly employs a phase-shifting power supply method. To eliminate the impact of three-phase unbalanced power loads on the power grid, traction substations along the line use a phase-shifting connection method. Because the voltage phases differ between sections, a certain number of de-energized zones are required. This affects the locomotive's speed when passing through these sections, which is unsuitable for the development of heavy-haul railways. Furthermore, this method is also unsuitable for small-scale regional lines where the lines are short and the number of traction substations is insufficient.

[0003] To address this issue, the in-phase traction power supply system demonstrates significant advantages. During operation, the in-phase power supply mode improves power quality, reduces the impact of the traction power supply system on the power grid, and fundamentally avoids the problem of "excessive phase separation" during operation. This is achieved by installing high-power static power converters (SPCs) in the traction substations, directly converting the three-phase AC power from the traction substations into 27.5kV / 50Hz single-phase AC power. Because the number of SPCs connected to the line is random, the combination of phase synchronization circuit breakers across the entire line is diverse, making the connection method more flexible. Relying solely on traditional distance protection and overcurrent protection methods, while also considering selectivity and speed, inevitably presents certain difficulties. Therefore, researching a contact wire feeder relay protection method suitable for through-type in-phase power supply is of great significance for the safe and stable operation of electrified railways. Summary of the Invention

[0004] In view of this, the present invention aims to propose a relay protection method for contact network of a through-type in-phase power supply system, providing a scientific, reasonable, fast, and accurate relay protection method for contact network feeders. This method is a relay protection method for contact network of a through-type in-phase power supply system, which can realize relay protection of contact network feeders under different operating modes and ensure the selectivity of relay protection.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] A method for relay protection of a through-type in-phase power supply system contact network includes at least one of the following steps:

[0007] S1. In the same phase power supply system, a protection device is installed in each traction substation and section substation to collect analog quantity information and remote signaling information of the substation respectively.

[0008] S2. Each protection device is set with 6 levels of protection action delay according to the site requirements, namely t1, t2, t3, t4, t5, and t6. When a fault occurs in the contact network, the bus voltage drops and the fault current is much greater than the load current. At this time, the protection device in the station determines that a fault has occurred in the contact network and enters the protection processing state.

[0009] S3. After the protection device waits for the protection action delay to be satisfied, it disconnects the line where the fault is located to complete the isolation. The protection device then exits the protection processing state and resumes normal operation.

[0010] Furthermore, in step S1, the analog information includes the bus voltage value, incoming current and outgoing current; the remote signaling information includes the position signals of the incoming line, feeder and circuit breaker on the bus.

[0011] Furthermore, step S2 includes at least one of the following situations:

[0012] A1. After the protection device enters the protection processing state, if it determines that the sum of the currents of each incoming line of the busbar is not equal to the sum of the currents of each outgoing line, the protection device determines that there is a busbar fault. At this time, the delay time of the protection action is t1.

[0013] A2. After the protection device enters the protection processing state, if it is determined that the current flow direction of the up and down feeder lines in a certain section is flowing into the bus, the protection operation of the two feeders will be blocked.

[0014] A3. After the protection device enters the protection processing state, if it is a traction substation, and the current magnitudes of the upstream and downstream feeder lines in the judgment section are equal and the current direction is both outflowing from the bus, or if the operating condition is that any line is simultaneously supplying power to the upstream and downstream (first generation and second generation cases), then the protection action delay for the upstream and downstream feeder lines is t5. The time setting depends on the site conditions.

[0015] A4. After the protection device enters the protection processing state, if it is a section, and the current magnitudes of the upstream and downstream feeder lines in the judgment section are equal and the current direction is outflow from the bus, then the protection action delay for the upstream and downstream feeder lines is t4. The time setting depends on the site conditions.

[0016] A5. After the protection device enters the protection processing state, if it is determined that the current magnitudes of the upstream and downstream feeder lines in the interval are equal, and the current directions are one flowing out of the bus and one flowing into the bus, then the protection action delay for the feeder line flowing out of the bus is t2, while the protection action for the feeder line flowing into the bus is blocked.

[0017] A6. After the protection device enters the protection processing state, if it determines that the current magnitudes of the up and down feeder lines in the section are equal, and after a period of time, the current magnitudes become unequal, then the protection action delay for the feeder with the larger current is t3.

[0018] A7. After the protection device enters the protection processing state, if it determines that the current corresponding to the upstream and downstream feeder lines in the interval is flowing out of the bus, and the current of the two feeder lines is not equal, then the protection action delay corresponding to the feeder with the larger current is t2, and the protection action delay corresponding to the feeder with the smaller current is t6.

[0019] Furthermore, in step S2, the protection action delays set for the six levels are t1, t2, t3, t4, t5, and t6, with the values ​​of the protection action delays from t1 to t5 increasing sequentially.

[0020] Furthermore, this solution discloses an electronic device, including a processor and a memory communicatively connected to the processor and used to store executable instructions of the processor, wherein the processor is used to execute a relay protection method for a through-type in-phase power supply system contact network.

[0021] Furthermore, this solution discloses a server, including at least one processor and a memory communicatively connected to the processor. The memory stores instructions executable by the at least one processor, which are executed by the processor to cause the at least one processor to perform a relay protection method for a through-type in-phase power supply system.

[0022] Furthermore, this solution discloses a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a relay protection method for a through-type in-phase power supply system contact network.

[0023] Compared with existing technologies, the contact network relay protection method for a through-type in-phase power supply system described in this invention has the following advantages:

[0024] (1) The contact network relay protection method of the through-type in-phase power supply system described in this invention adopts the method of comparing the relative values ​​of the up and down currents in the same interval to select the protection action delay for different numbers of power supply inputs. This not only increases the selectivity of protection, but also avoids the difficulty of setting the setting value (absolute setting value) in traditional protection.

[0025] (2) The contact network relay protection method of the through-type in-phase power supply system described in this invention takes into account a wide range of situations when setting the protection action delay for various operating modes, covering various operating conditions of the up and down line currents in the section, and increasing the applicability of this protection scheme in different operating modes.

[0026] (3) The contact network relay protection method of the through-type in-phase power supply system described in this invention has low requirements for communication between stations. When communication between stations is abnormal, this protection scheme is not affected and can work normally. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 This is a flowchart illustrating the implementation of a relay protection method for a through-type in-phase power supply system.

[0029] Figure 2 Topology diagram of a single-phase power supply system.

[0030] Figure 3 Topology diagram of a dual-ended power supply system with in-phase power supply. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] A relay protection method for a through-type in-phase power supply system contact network, characterized by comprising the following steps:

[0034] (1) Firstly, in the same phase power supply system, each traction substation and section substation shall be equipped with a protection device, and each device shall collect analog quantity information and remote signaling information of its own substation.

[0035] (2) Each device is set with 6 levels of protection action delay according to the site requirements, namely t1, t2, t3, t4, t5 and t6. When the contact network fails, the bus voltage drops and the fault current is much greater than the load current. At this time, the protection device in the station determines that the contact network has failed and enters the protection processing state.

[0036] (3) After the protection device enters the protection processing state, if it is determined that the sum of the currents of each incoming line of the busbar is not equal to the sum of the currents of each outgoing line, the protection device will determine that the busbar is faulty. At this time, the delay time of the protection action is t1.

[0037] (4) After the protection device enters the protection processing state, if it is determined that the current flow direction of the up and down feeder lines in a certain section is flowing into the bus, the protection operation of the two feeders will be blocked.

[0038] (5) After the protection device enters the protection processing state, if it is a traction substation, the current magnitude of the corresponding up and down feeder lines in the judgment section is equal, and the current direction is the outflow from the bus, or the operation is that any line is simultaneously supplying power to the up and down (first generation and second generation), then the protection action delay of the corresponding up and down feeder lines is t5, and the time setting depends on the site conditions.

[0039] (6) After the protection device enters the protection processing state, if it is a section, the current magnitude of the upstream and downstream feeder lines in the section is equal and the current direction is out of the bus. Then the protection action delay of the upstream and downstream feeder lines is t4. The time setting depends on the site conditions.

[0040] (7) After the protection device enters the protection processing state, if it is determined that the current magnitudes of the upstream and downstream feeder lines in the interval are equal and the current directions are one outflowing from the busbar and one inflowing into the busbar, then the protection action delay of the feeder line outflowing from the busbar is t2, while the protection action of the feeder line inflowing into the busbar is blocked.

[0041] (8) After the protection device enters the protection processing state, if it is determined that the current magnitudes of the up and down feeder lines in the section are equal, and after a period of time, the current magnitudes become unequal, then the protection action delay for the feeder with the larger current is t3.

[0042] (9) After the protection device enters the protection processing state, if the current corresponding to the up and down feeder lines in the section is both outflowing from the bus, and the current of the two feeders is not equal, then the protection action delay corresponding to the feeder with the larger current is t2, and the protection action delay corresponding to the feeder with the smaller current is t6.

[0043] (10) After the protection device waits for the protection action delay to be satisfied, it will disconnect the line where the fault is located to complete the isolation. The protection device will then exit the protection processing state and return to normal operation.

[0044] Furthermore, in (1), the same-phase power supply system refers to the system that can convert the three-phase AC power of the traction substation incoming line into 27.5kV / 50Hz single-phase AC power through AC-DC-AC conversion technology, and then supply power to the contact network. This system has a more flexible power supply mode and reduces the impact of the traction power supply system on the grid side.

[0045] The aforementioned installation of a protection device refers to the installation of a relevant device in the traction substation or sectioning station to realize the relay protection of the contact wire feeder.

[0046] Furthermore, in (1), the analog information collected by the protection device includes the voltage value of the bus, the incoming current and the outgoing current; the remote signaling information includes the position signals of the incoming line, the feeder and the circuit breaker and the disconnection on the bus.

[0047] Furthermore, in (2), "six levels of protection action delay are set, namely t1, t2, t3, t4, t5, and t6, wherein the values ​​of the protection action delay from t1 to t5 increase sequentially."

[0048] Furthermore, in step (10), the fault isolation is completed by disconnecting the line where the fault is located. At this time, the fault current disappears and the bus voltage is restored. The conditions for the protection device to determine that the contact network has failed are not met, so the protection device exits the protection processing state.

[0049] Furthermore, the flowchart of the steps described above is as follows: Figure 1 As shown.

[0050] The present invention will be described in detail through embodiments.

[0051] The protection action delays in the protection device are set as follows: t1 = 0.15s, t2 = 0.25s, t3 = 0.04s, t4 = 0.45s, t5 = 0.85s, t6 = 0.45s. In actual engineering practice, the circuit breaker action time is generally 0.05s, which is set as TM1. The fault current calculation time is 0.02s, which is set as TM2.

[0052] Running Example 1:

[0053] 1. For example Figure 2 In the operational topology shown, the time when the fault occurs at point A is called the fault occurrence time.

[0054] 2. Since point A is near the end of the feeder, the current at feeder 13 and feeder 14 is almost zero. The current of feeder 10 in the interval is greater than that of feeder 9. At this time, the condition of step (8) is met. Feeder 10 is isolated first. The time relative to the time of the fault occurrence is: 20ms (TM2) + 250ms (t2 delay) + 50ms (circuit breaker operation time) = 320ms; the operation time of feeder 9 is: 20ms (TM2) + 250ms (t2 delay) + 450ms (t6 delay) = 720ms. This time exceeds the operation time of feeder 13 below. At this time, the protection device has exited the protection processing state, and feeder 9 will not operate.

[0055] 3. After feeder 10 trips, the currents at feeder 13 and feeder 14 are equal in magnitude but opposite in direction, satisfying the condition in step (7). Feeder 13 is isolated, and the time relative to the time of the fault occurrence is: 20ms (TM2) + 250ms (t2 delay) + 50ms (circuit breaker operating time) + 20ms (TM2) + 250ms (t2 delay) + 50ms (circuit breaker operating time) = 640ms

[0056] 4. The currents at feeder 5 and feeder 6 are equal, satisfying the condition in step (5). The protection action delay relative to the fault occurrence time is: 20ms (TM2) + 850ms (t5 delay) = 870ms. This time exceeds the action time of feeder 13. At this time, the protection device has exited the protection processing state, and feeders 5 and 6 will not operate.

[0057] Running Example 2:

[0058] 1. For example Figure 3 In the operational topology shown, the time when the fault occurs at point B is called the fault occurrence time.

[0059] 2. When a busbar fault occurs and the sum of the currents of each incoming line of the busbar is not equal to the sum of the currents of each outgoing line of the busbar, the condition in step (2) is met. At this time, incoming line 1, incoming line 2, feeder 5, and feeder 6 are isolated first. The time relative to the time of the fault occurrence is: 20ms (TM2) + 150ms (t1) + 50ms (circuit breaker operating time) = 220ms.

[0060] 3. The current magnitudes at the positions of feeder 7 and feeder 8 are equal, satisfying the condition in step (6). The protection action delay relative to the fault occurrence time is: 20ms (TM2) + 450ms (t4 delay) = 470ms. This time exceeds the time when incoming line 1, incoming line 2, feeder 5, and feeder 6 are first isolated. At this time, the protection device has exited the protection processing state, and feeder 7 and feeder 8 do not operate.

[0061] 4. The current magnitudes at feeder 13 and feeder 14 are equal, satisfying the condition in step (5). The protection action delay relative to the fault occurrence time is: 20ms (TM2) + 850ms (t5 delay) = 870ms. This time exceeds the time when incoming lines 1, 2, 5, and 6 are first isolated. At this time, the protection device has exited the protection processing state, and feeder 13 and feeder 14 do not operate.

[0062] Running Example 3:

[0063] 1. For example Figure 3 In the operational topology shown, the time when the fault occurs at point C is called the fault occurrence time.

[0064] 2. The current of feeder 10 in the interval is greater than that of feeder 9. At this time, the condition of step (8) is met. Feeder 10 is isolated first. The time relative to the time of the fault occurrence is: 20ms (TM2) + 250ms (t2 delay) = 270ms; the operation time of feeder 9 is: 20ms (TM2) + 250ms (t2 delay) + 450ms (t6 delay) = 720ms. This time exceeds the operation time of feeder 13 below. At this time, the protection device has exited the protection processing state, and feeder 9 will not operate.

[0065] 3. Since point C is near the near end of the feeder, the currents at feeder 13 and feeder 14 are equal at the beginning. After feeder 10 is isolated, the current in feeder 13 is greater than the current in feeder 14, which satisfies the condition in step (7). The time for feeder 13 to be isolated relative to the time of the fault occurrence is: 20ms (TM2) + 250ms (t2 delay) + 50ms (circuit breaker operating time) + 20ms (TM2) + 40ms (t3 delay) + 50ms (circuit breaker operating time) = 430ms.

[0066] 4. The currents at feeder 5 and feeder 6 are equal, satisfying the condition in step (5). The protection action delay relative to the fault occurrence time is: 20ms (TM2) + 850ms (t5 delay) = 870ms. This time exceeds the action time of feeder 13. At this time, the protection device has exited the protection processing state, and feeders 5 and 6 will not operate.

[0067] Running Example 4:

[0068] 1. For example Figure 3 In the operating topology shown, the time when the fault occurs at point D is called the fault occurrence time.

[0069] 2. The current of feeder 10 in the interval is greater than that of feeder 9. At this time, the condition of step (8) is met. Feeder 10 is isolated first. The time relative to the time of the fault occurrence is: 20ms (TM2) + 250ms (t2 delay) + 50ms (circuit breaker operation time) = 320ms; the operation time of feeder 9 is: 20ms (TM2) + 250ms (t2 delay) + 450ms (t6 delay) = 720ms. At this time, the protection device has exited the protection processing state, and feeder 9 will not operate.

[0070] 3. The current in feeder 13 in the interval is greater than that in feeder 14. At this time, the condition in step (8) is met. Feeder 13 is isolated first. The time relative to the time of the fault occurrence is: 20ms (TM2) + 250ms (t2 delay) + 50ms (circuit breaker operation time) = 320ms; the operation time of feeder 14 is: 20ms (TM2) + 250ms (t2 delay) + 450ms (t6 delay) = 720ms. At this time, the protection device has exited the protection processing state, and feeder 14 will not operate.

[0071] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0072] In the several embodiments provided in this application, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the division of units described above is merely a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. The aforementioned units may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for relay protection of contact network in a through-type in-phase power supply system, characterized in that, Includes at least one of the following steps: S1. In the same phase power supply system, a protection device is installed in each traction substation and section substation to collect analog quantity information and remote signaling information of the substation respectively. S2. Each protection device is set with 6 levels of protection action delay according to the site requirements, namely t1, t2, t3, t4, t5, and t6. When a fault occurs in the contact network, the bus voltage drops and the fault current is much greater than the load current. At this time, the protection device in the station determines that a fault has occurred in the contact network and enters the protection processing state. S3. After the protection action delay is satisfied, the protection device disconnects the line where the fault is located to complete the isolation, and the protection device then exits the protection processing state and resumes normal operation. In step S1, the analog information includes the bus voltage value, incoming current and outgoing current; the remote signaling information includes the position signals of the incoming line, feeder and circuit breaker on the bus. Step S2 includes at least one of the following situations: A1. After the protection device enters the protection processing state, if it determines that the sum of the currents of each incoming line of the busbar is not equal to the sum of the currents of each outgoing line, the protection device determines that there is a busbar fault. At this time, the delay time of the protection action is t1. A2. After the protection device enters the protection processing state, if it is determined that the current flow direction of the up and down feeder lines in a certain section is flowing into the bus, the protection operation of the two feeders will be blocked. A3. After the protection device enters the protection processing state, if it is a traction substation, and the current magnitudes of the upstream and downstream feeder lines in the judgment section are equal and the current direction is both flowing out of the bus, or if the operating condition is that any line is simultaneously supplying power to the upstream and downstream feeders, then the protection action delay for the upstream and downstream feeders is t5. The time setting depends on the site conditions. A4. After the protection device enters the protection processing state, if it is a section, and the current magnitudes of the upstream and downstream feeder lines in the judgment section are equal and the current direction is outflow from the bus, then the protection action delay for the upstream and downstream feeder lines is t4. The time setting depends on the site conditions. A5. After the protection device enters the protection processing state, if it is determined that the current magnitudes of the upstream and downstream feeder lines in the interval are equal, and the current directions are one flowing out of the bus and one flowing into the bus, then the protection action delay for the feeder line flowing out of the bus is t2, while the protection action for the feeder line flowing into the bus is blocked. A6. After the protection device enters the protection processing state, if it determines that the current magnitudes of the up and down feeder lines in the section are equal, and after a period of time, the current magnitudes become unequal, then the protection action delay for the feeder with the larger current is t3. A7. After the protection device enters the protection processing state, if it determines that the current corresponding to the upstream and downstream feeder lines in the interval is flowing out of the bus, and the current of the two feeder lines is not equal, then the protection action delay corresponding to the feeder with the larger current is t2, and the protection action delay corresponding to the feeder with the smaller current is t6.

2. The method for relay protection of contact network in a through-type in-phase power supply system according to claim 1, characterized in that, In step S2, the protection action delays for the six different levels are set as t1, t2, t3, t4, t5, and t6, with the values ​​of the protection action delays from t1 to t5 increasing sequentially.

3. An electronic device, comprising a processor and a memory communicatively connected to the processor and used to store instructions executable by the processor, characterized in that: The processor is used to execute the contact network relay protection method for a through-type in-phase power supply system as described in claim 1.

4. A server, characterized in that: It includes at least one processor and a memory communicatively connected to the processor, the memory storing instructions executable by the at least one processor, the instructions being executed by the processor to cause the at least one processor to perform a contact network relay protection method for a through-type in-phase power supply system as described in claim 1.

5. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, it implements the contact network relay protection method for a through-type in-phase power supply system as described in claim 1.

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