Direct-current converter station protection method and system based on alternating-current section power loss

Abstract

The invention discloses a direct-current converter station protection method and system based on alternating-current section power loss, which is suitable for a converter station with two alternating-current outgoing lines, and comprises the following steps: judging whether the converter station and an alternating-current station have a single-line fault or not according to a first circuit breaker state signal of the converter station and a second circuit breaker state signal of the alternating-current station; if yes, a direct current reduction command is sent to a direct current control and protection system of the converter station, so that the direct current transmission power is reduced to a preset value, and the voltage of the converter station side is within the bearable range of the converter station device after the subsequent sudden fault of the other circuit in normal operation, namely after the alternating current section is powered off; and the situation that equipment is damaged by overvoltage of the direct current converter station after the alternating current section loses power is avoided.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a direct current converter station protection method and system based on alternating current section power failure. Background Art

[0002] In the high-voltage direct current transmission system, the converter station is a key facility for the mutual conversion between AC and DC. During the operation of the converter station, when the DC converter station loses connection with the AC system, that is, when the AC section loses power, the overvoltage generated is particularly serious. If the DC system is not shut down in time, a high overvoltage may be formed in the AC and DC systems in the station, or the arrester energy may exceed the limit, seriously affecting the safety of the equipment.

[0003] For conventional DC projects, the overvoltage after the AC section loses power is caused by the power surplus problem, that is, after the AC section at the receiving end loses power, power is continuously injected into the AC filter capacitor, resulting in a high continuous overvoltage, causing the arrester to bear a large energy stress. For flexible DC projects, the flexible DC system usually adopts fixed DC voltage control at the sending end and fixed power control at the receiving end. After the AC section at the receiving end loses power, the DC voltage rises briefly and then quickly drops back to the rated value under the regulation of the sending end (fixed DC voltage side), and the DC side will not be over-voltage. However, since the reference value of the active power does not change after the receiving end loses power, and the actual active power suddenly changes to 0, the output voltage of the converter reaches the limit value, which in turn causes the voltage on the valve side and grid side of the converter transformer to increase, and the valve side arrester of the receiving end bridge arm reactor, the valve side arrester of the converter transformer, and the grid side arrester of the converter transformer will be subjected to overvoltage.

[0004] Therefore, the AC section power failure judgment system is usually used as an important protection when the DC converter station loses connection with the AC system. The AC section power failure judgment system can send a locking command to the DC system when the DC converter station loses connection with the AC system, quickly lock the DC, and prevent overvoltage risks. However, the existing AC section power failure judgment system has a long action time, which is the sum of the device judgment time, channel transmission time, relay action time, and circuit breaker action time. If there is an intermediate relay, the time will increase. Within this time range, the voltage on the converter station side has reached the overvoltage peak, and the thyristor or IGBT components of the DC system have been damaged. Therefore, how to protect the equipment of the DC converter station from damage when the AC section power failure occurs has become a problem that needs to be solved urgently. Summary of the invention

[0005] The embodiment of the present invention provides a DC converter station protection method and system based on AC section power failure. When only one AC line is left in the DC transmission section, the DC power is reduced to a certain power value, so that after the AC section power failure occurs, the voltage on the converter station side is within the tolerable range of the converter station device, thereby avoiding the situation where the DC converter station overvoltage exceeds the damage to the equipment after the AC section power failure.

[0006] An embodiment of the present invention provides a DC converter station protection method based on AC section power failure, comprising: Acquire a first circuit breaker status signal of a converter station and a second circuit breaker status signal of an AC station; wherein the converter station is a converter station with two AC outgoing lines, and the AC station is an AC station on the opposite side of the AC outgoing line of the converter station; Determining the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal; When it is determined that the line status between the converter station and the AC station is a single-line fault, a DC reduction command is sent to the DC control and protection system of the converter station to reduce the DC transmission power of the converter station to a preset value.

[0007] Furthermore, the DC converter station protection method based on AC section power failure described in the above embodiment further includes: When it is determined that the line state between the converter station and the AC station is AC section power failure, a DC blocking command is sent to the DC control and protection system of the converter station.

[0008] Furthermore, the first circuit breaker status signal includes: a first switch position signal of a first circuit breaker carried by the converter station, and a first trip protection signal of the first circuit breaker; The second circuit breaker status signal includes: a second switch position signal of a second circuit breaker carried by the AC station, and a second trip protection signal of the second circuit breaker.

[0009] Further, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal includes: When a single-line tripping occurs on the converter station side according to the first circuit breaker status signal, or when a single-line tripping occurs on the AC station side according to the second circuit breaker status signal, it is determined that the line status between the converter station and the AC station is a single-line fault.

[0010] Furthermore, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal further includes: According to the first circuit breaker status signal, it is determined that a single-line trip occurs on any line on the converter station side, and according to the second circuit breaker status signal, it is determined that a single-line trip occurs on another line on the AC station side. or according to the first circuit breaker status signal, determine that a double-line trip occurs on the converter station side; Or when it is determined according to the second circuit breaker status signal that a double-line trip occurs on the AC station side, it is determined that the line status between the converter station and the AC station is AC section power failure.

[0011] Another embodiment of the present invention provides a DC converter station protection system based on AC section power failure, comprising: a main station mounted on a converter station with two AC outgoing lines, and a substation mounted on an AC station on the opposite side of the AC outgoing line of the converter station; The substation is used to collect the second circuit breaker status signal of the AC station where it is located; The master station is used to collect a first circuit breaker status signal of the converter station where it is located, and to obtain a second circuit breaker status signal of the substation; to determine the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal; and when it is determined that the line status between the converter station and the AC station is a single-line fault, to send a DC reduction command to the DC control and protection system of the converter station, so as to reduce the DC transmission power of the converter station to a preset value.

[0012] Furthermore, the master station is also used to send a DC blocking command to the DC control and protection system of the converter station when it is determined that the line status between the converter station and the AC station is AC section power failure.

[0013] Furthermore, the first circuit breaker status signal includes: a first switch position signal of a first circuit breaker carried by the converter station, and a first trip protection signal of the first circuit breaker; The second circuit breaker status signal includes: a second switch position signal of a second circuit breaker carried by the AC station, and a second trip protection signal of the second circuit breaker.

[0014] Further, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal includes: When a single-line tripping occurs on the converter station side according to the first circuit breaker status signal, or when a single-line tripping occurs on the AC station side according to the second circuit breaker status signal, the line status between the converter station and the AC station is a single-line fault.

[0015] Furthermore, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal further includes: According to the first circuit breaker status signal, it is determined that a single-line trip occurs on any line on the converter station side, and according to the second circuit breaker status signal, it is determined that a single-line trip occurs on another line on the AC station side. or according to the first circuit breaker status signal, determine that a double-line trip occurs on the converter station side; Or when it is determined according to the second circuit breaker status signal that a double-line trip occurs on the AC station side, it is determined that the line status between the converter station and the AC station is AC section power failure.

[0016] The following beneficial effects are achieved by implementing the present invention: The present invention provides a DC converter station protection method and system based on AC section power failure, which is suitable for a converter station with two AC outgoing lines. By judging whether a single-line fault occurs between the converter station and the AC station based on a first circuit breaker status signal of the converter station and a second circuit breaker status signal of the AC station, if so, a DC reduction command is sent to a DC control and protection system of the converter station to reduce the DC transmission power to a preset value, so that when another line in normal operation fails in a subsequent sudden fault, that is, after an AC section power failure occurs, the voltage on the converter station side is within the tolerable range of the converter station device, thereby avoiding the situation where the DC converter station overvoltage exceeds the damage to the equipment after the AC section power failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention is a flowchart of a method for protecting a DC converter station based on AC section power failure provided in one embodiment of the present invention.

[0018] Figure 2 The present invention is a schematic structural diagram of a DC converter station protection system based on AC section power failure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0019] 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.

[0020] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0022] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0025] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0026] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0027] See also Figure 1 , is a flow chart of a DC converter station protection method based on AC section power failure provided by an embodiment of the present invention, comprising: S1. Obtaining a first circuit breaker status signal of a converter station and a second circuit breaker status signal of an AC station; wherein the converter station is a converter station with two AC outgoing lines, and the AC station is an AC station on the opposite side of the AC outgoing line of the converter station; Preferably, the first circuit breaker status signal includes: a first switch position signal of a first circuit breaker carried by the converter station, and a first trip protection signal of the first circuit breaker; The second circuit breaker status signal includes: a second switch position signal of a second circuit breaker carried by the AC station, and a second trip protection signal of the second circuit breaker.

[0028] In a preferred embodiment of the present invention, the first switch position signal and the second switch position signal are used to distinguish the three-phase switch operation state and the single-phase switch operation state of the first circuit breaker and the second circuit breaker. Specifically, the three-phase switch operation state judgment logic is: when the circuit breaker maintenance pressure plate is not put into operation, when any two phases of the circuit breaker HWJ is 1, and any two phases of the circuit breaker TWJ is 0, it is judged that the circuit breaker is in the closed operation state; the single-phase switch operation state judgment logic is: when the circuit breaker maintenance pressure plate is not put into operation, when the circuit breaker phase HWJ is 1, and the phase TWJ is 0, it is judged that the circuit breaker phase is in the closed operation state.

[0029] S2. judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal; Preferably, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal includes: S21. When it is determined according to the first circuit breaker status signal that a single-line trip occurs on the converter station side, or when it is determined according to the second circuit breaker status signal that a single-line trip occurs on the AC station side, it is determined that the line status between the converter station and the AC station is a single-line fault.

[0030] Preferably, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal further includes: S22, determining that a single-line trip occurs on any line on the converter station side according to the first circuit breaker status signal, and determining that a single-line trip occurs on another line on the AC station side according to the second circuit breaker status signal, or according to the first circuit breaker status signal, determine that a double-line trip occurs on the converter station side; Or when it is determined according to the second circuit breaker status signal that a double-line trip occurs on the AC station side, it is determined that the line status between the converter station and the AC station is AC section power failure.

[0031] In a preferred embodiment of the present invention, the judgment logic for determining whether the first circuit breaker and the second circuit breaker are tripped includes: When it is determined that the circuit breaker is in operation and any two different phase protection signals or any three trip protection signals are turned on, the circuit breaker is judged to be tripped; When it is determined that the circuit breaker is in operation, and any phase switch HWJ or TWJ is switched on, and any two phases of TWJ of the circuit breaker are 1, and any two phases of HWJ are 0, the circuit breaker is judged to be tripped; When it is determined that the phase of the circuit breaker is in operation, any one of the protection signals of the phase or any of the three trip protection signals is turned on, it is determined that the phase of the circuit breaker is tripped; When it is determined that the phase of the circuit breaker is in operation, and the switch HWJ or TWJ of the phase is switched on, and the TWJ of the phase of the circuit breaker is 1 and the HWJ of the phase is 0, it is determined that the phase of the circuit breaker is tripped.

[0032] S3. When it is determined that the line status between the converter station and the AC station is a single-line fault, a DC reduction command is sent to the DC control and protection system of the converter station to reduce the DC transmission power of the converter station to a preset value.

[0033] Preferably, the DC converter station protection method based on AC section power failure as described in the above embodiment further includes: S4. When it is determined that the line state between the converter station and the AC station is AC section power failure, a DC blocking command is sent to the DC control and protection system of the converter station.

[0034] In a preferred embodiment of the present invention, when it is determined that the circuit breaker of any circuit of the converter station has tripped, or the circuit breaker of any circuit of the opposite AC station has tripped, it is determined that line N-1 is detected, that is, the converter station has only one normal operating transmission line left, so in order to avoid the voltage on the converter station side reaching the voltage peak when the last line N-1 occurs (that is, the AC section loses power), causing the thyristor or IGBT components of the DC system to be damaged. In this embodiment, when line N-1 is detected, a DC reduction command is sent to the DC control and protection system of the converter station to realize the DC reduction function, so that when the last line N-1 occurs (that is, the AC section loses power), the highest overvoltage on the converter station side is within the voltage range that the converter station device can withstand.

[0035] It should be noted that after determining that a single-line fault has occurred in the line, when it is determined that another circuit has failed based on the first circuit breaker status signal and the second circuit breaker status signal, that is, when it is determined that both circuits of the converter station are faulty, a DC locking command is immediately sent to the DC control and protection system of the converter station to achieve DC locking and ensure the safety of the converter station and the AC station.

[0036] When it is determined that the circuit breakers of both circuits of the converter station have tripped, or the circuit breakers of both circuits on the AC station side have tripped, or when the circuit breaker of any circuit of the converter station trips, the circuit breaker of another circuit of the AC station also trips, it is determined that an AC section power failure has been detected in the line, and a DC locking command is immediately sent to the DC control and protection system of the converter station to achieve DC locking.

[0037] A DC converter station protection method based on AC section power failure provided in an embodiment of the present invention is applicable to a converter station with two AC outgoing lines. By judging whether a single-line fault occurs between the converter station and the AC station based on a first circuit breaker status signal of the converter station and a second circuit breaker status signal of the AC station, if so, a DC reduction command is sent to a DC control and protection system of the converter station to reduce the DC transmission power to a preset value, so that when another line in normal operation fails in a subsequent sudden fault, that is, after an AC section power failure occurs, the voltage on the converter station side is within the tolerable range of the converter station device, thereby avoiding the situation where the DC converter station overvoltage exceeds the equipment damage after the AC section power failure.

[0038] See also Figure 2 , is a structural schematic diagram of a DC converter station protection system based on AC section power failure provided by an embodiment of the present invention, comprising: a main station mounted on a converter station with two AC outgoing lines, and a substation mounted on an AC station on the opposite side of the AC outgoing line of the converter station; The substation is used to collect the second circuit breaker status signal of the AC station where it is located; The master station is used to collect a first circuit breaker status signal of the converter station where it is located, and to obtain a second circuit breaker status signal of the substation; to determine the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal; and when it is determined that the line status between the converter station and the AC station is a single-line fault, to send a DC reduction command to the DC control and protection system of the converter station, so as to reduce the DC transmission power of the converter station to a preset value.

[0039] In a preferred embodiment of the present invention, the substation and the main station are communicatively connected to form a DC converter station protection system with an AC section power failure detection function.

[0040] It should be further explained that both the substation and the main station include a signal receiving module for collecting circuit breaker status signals.

[0041] Furthermore, the master station further includes: a line identification module and a command sending module; The circuit breaker state judgment module is used to judge the line state between the converter station and the AC station according to the first circuit breaker state signal and the second circuit breaker state signal; The command sending module is used to send a DC reduction command to the DC control and protection system of the converter station when it is determined that the line status between the converter station and the AC station is a single-line fault, so as to reduce the DC transmission power of the converter station to a preset value.

[0042] It should be further explained that in order to reduce the operational pressure of the main station, a line identification module and a command sending module can be set in the substation; so that the substation can judge whether a single-line fault or a double-line fault occurs on the AC station side through the second circuit breaker status signal of the AC station circuit breaker where it is located, and when a single-line fault or a double-line fault occurs on the AC station side, the result is fed back to the main station, so that the main station can send a DC reduction command or a DC locking command to the DC control and protection system of the converter station in combination with the line status of the converter station and the line status of the AC station side.

[0043] Preferably, the master station is further used to send a DC blocking command to the DC control and protection system of the converter station when it is determined that the line status between the converter station and the AC station is AC section power failure.

[0044] Preferably, the first circuit breaker status signal includes: a first switch position signal of a first circuit breaker carried by the converter station, and a first trip protection signal of the first circuit breaker; The second circuit breaker status signal includes: a second switch position signal of a second circuit breaker carried by the AC station, and a second trip protection signal of the second circuit breaker.

[0045] Preferably, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal includes: When a single-line tripping occurs on the converter station side according to the first circuit breaker status signal, or when a single-line tripping occurs on the AC station side according to the second circuit breaker status signal, the line status between the converter station and the AC station is a single-line fault.

[0046] Preferably, judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal further includes: According to the first circuit breaker status signal, it is determined that a single-line trip occurs on any line on the converter station side, and according to the second circuit breaker status signal, it is determined that a single-line trip occurs on another line on the AC station side. or according to the first circuit breaker status signal, determine that a double-line trip occurs on the converter station side; Or when it is determined according to the second circuit breaker status signal that a double-line trip occurs on the AC station side, it is determined that the line status between the converter station and the AC station is AC section power failure.

[0047] A DC converter station protection system based on AC section power failure provided in an embodiment of the present invention is suitable for a converter station with two AC outgoing lines. By judging whether a single-line fault occurs between the converter station and the AC station based on a first circuit breaker status signal of the converter station and a second circuit breaker status signal of the AC station, if so, a DC reduction command is sent to the DC control and protection system of the converter station to reduce the DC transmission power to a preset value, so that when the other normally operating line fails in a subsequent sudden fault, that is, after the AC section power failure occurs, the voltage on the converter station side is within the tolerable range of the converter station device, thereby avoiding the situation where the DC converter station overvoltage exceeds the damage to the equipment after the AC section power failure.

[0048] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A DC converter station protection method based on AC section power failure, characterized in that: include: Acquire a first circuit breaker status signal of a converter station and a second circuit breaker status signal of an AC station; wherein the converter station is a converter station with two AC outgoing lines, and the AC station is an AC station on the opposite side of the AC outgoing line of the converter station; Determining the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal; When it is determined that the line status between the converter station and the AC station is a single-line fault, a DC reduction command is sent to the DC control and protection system of the converter station to reduce the DC transmission power of the converter station to a preset value.

2. A DC converter station protection method based on AC section power failure according to claim 1, characterized in that: Also includes: When it is determined that the line state between the converter station and the AC station is AC section power failure, a DC blocking command is sent to the DC control and protection system of the converter station.

3. A DC converter station protection method based on AC section power failure according to claim 2, characterized in that: The first circuit breaker state signal includes: a first switch position signal of a first circuit breaker carried by the converter station, and a first trip protection signal of the first circuit breaker; The second circuit breaker status signal includes: a second switch position signal of a second circuit breaker carried by the AC station, and a second trip protection signal of the second circuit breaker.

4. A DC converter station protection method based on AC section power failure as claimed in claim 3, characterized in that: The determining, according to the first circuit breaker status signal and the second circuit breaker status signal, the line status between the converter station and the AC station comprises: When a single-line tripping occurs on the converter station side according to the first circuit breaker status signal, or when a single-line tripping occurs on the AC station side according to the second circuit breaker status signal, it is determined that the line status between the converter station and the AC station is a single-line fault.

5. A DC converter station protection method based on AC section power failure according to claim 4, characterized in that: The method of judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal further includes: According to the first circuit breaker status signal, it is determined that a single-line trip occurs on any line on the converter station side, and according to the second circuit breaker status signal, it is determined that a single-line trip occurs on another line on the AC station side. or according to the first circuit breaker status signal, determine that a double-line trip occurs on the converter station side; Or when it is determined according to the second circuit breaker status signal that a double-line trip occurs on the AC station side, it is determined that the line status between the converter station and the AC station is AC section power failure.

6. A DC converter station protection system based on AC section power failure, characterized in that: include: A main station installed in a converter station with two AC outgoing lines, and a substation installed in the AC station on the opposite side of the converter station’s AC outgoing lines; The substation is used to collect the second circuit breaker status signal of the AC station where it is located; The master station is used to collect a first circuit breaker status signal of the converter station where it is located, and to obtain a second circuit breaker status signal of the substation; to determine the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal; and when it is determined that the line status between the converter station and the AC station is a single-line fault, to send a DC reduction command to the DC control and protection system of the converter station, so as to reduce the DC transmission power of the converter station to a preset value.

7. A DC converter station protection system based on AC section power failure as claimed in claim 6, characterized in that: The master station is further used to send a DC blocking command to the DC control and protection system of the converter station when it is determined that the line status between the converter station and the AC station is AC section power failure.

8. A DC converter station protection system based on AC section power failure as claimed in claim 7, characterized in that: The first circuit breaker state signal includes: a first switch position signal of a first circuit breaker carried by the converter station, and a first trip protection signal of the first circuit breaker; The second circuit breaker status signal includes: a second switch position signal of a second circuit breaker carried by the AC station, and a second trip protection signal of the second circuit breaker.

9. A DC converter station protection system based on AC section power failure as claimed in claim 8, characterized in that: The determining, according to the first circuit breaker status signal and the second circuit breaker status signal, the line status between the converter station and the AC station comprises: When a single-line tripping occurs on the converter station side according to the first circuit breaker status signal, or when a single-line tripping occurs on the AC station side according to the second circuit breaker status signal, the line status between the converter station and the AC station is a single-line fault.

10. A DC converter station protection system based on AC section power failure according to claim 9, characterized in that: The method of judging the line status between the converter station and the AC station according to the first circuit breaker status signal and the second circuit breaker status signal further includes: According to the first circuit breaker status signal, it is determined that a single-line trip occurs on any line on the converter station side, and according to the second circuit breaker status signal, it is determined that a single-line trip occurs on another line on the AC station side. or according to the first circuit breaker status signal, determine that a double-line trip occurs on the converter station side; Or when it is determined according to the second circuit breaker status signal that a double-line trip occurs on the AC station side, it is determined that the line status between the converter station and the AC station is AC section power failure.

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