Fault diagnosis method and system for bridge arm short circuit of converter valve of direct-current power transmission system

Abstract

The invention discloses a fault diagnosis method and a fault diagnosis system for short circuit of a converter valve bridge arm of a direct current power transmission system, and belongs to the technical field of fault diagnosis of the direct current power transmission system.The fault diagnosis method for the short circuit of the converter valve bridge arm of the direct current power transmission system confirms that a corresponding pulse signal word is a first pulse signal word at the moment of a direct current fault; determining a subsequent pulse signal word adjacent to the first pulse signal word as a second pulse signal word based on the commutation sequence of the three-phase current; according to the fault diagnosis method, solving is carried out based on the first pulse signal word and the second pulse signal word, the mark of the corresponding converter valve is obtained, and the converter valve with the fault is confirmed through the mark; according to the application, the instant pulse signal word based on the direct current fault is combined with the subsequent pulse signal word according to the commutation sequence, the faulted converter valve can be quickly positioned only by processing the pulse signal word, and timely processing of the fault is facilitated.

Description

Technical Field

[0001] The present application relates to the technical field of fault diagnosis of a direct current (DC) transmission system, and in particular to a method and system for diagnosing a short circuit in a converter valve bridge arm of a DC transmission system. Background Art

[0002] Converter valves are one of the most critical components of HVDC transmission and are extremely expensive to manufacture. If a short circuit occurs in a converter valve arm, the massive short-circuit current will damage the valves and cause a shutdown of the DC transmission system, resulting in significant economic losses. Therefore, rapid troubleshooting and rectification are crucial to restore DC transmission as quickly as possible.

[0003] When the bridge arm of the converter valve is short-circuited, valve short-circuit protection is generally configured to determine the cause. However, this can only implement protection action and cannot locate the specific converter valve where the fault occurs. Summary of the Invention

[0004] Purpose of the invention: The purpose of the embodiments of the present application is to provide a fault diagnosis method and system for a short circuit in a converter valve bridge arm of a DC transmission system, aiming to solve the technical problem in the prior art of being unable to locate a faulty converter valve.

[0005] Technical Solution: In a first aspect, embodiments of the present application provide a fault diagnosis method for a short circuit in a converter valve bridge arm of a direct current (DC) transmission system. The DC transmission system includes a converter valve group and a converter valve triggering system. The AC side of the converter valve group is connected to a three-phase AC current, and the DC side of the converter valve group is connected to a DC transmission line. The converter valve triggering system is connected to a control terminal of the converter valve group to output a pulse signal word to perform commutation control on the converter valve group.

[0006] The method comprises:

[0007] confirming a first pulse signal word, where the first pulse signal word is a pulse signal word at the moment of a DC fault;

[0008] confirming a second pulse signal word, where the second pulse signal word is a subsequent pulse signal word adjacent to the first pulse signal word based on a commutation sequence of the three-phase current;

[0009] A faulty converter valve is identified based on the first pulse signal word and the second pulse signal word.

[0010] In some embodiments, the step of confirming the first pulse signal word includes:

[0011] confirming the on-state current at the instant of the DC fault;

[0012] The first pulse signal word is confirmed based on the on-current at the moment of the DC fault.

[0013] In some embodiments, the step of confirming the DC fault instant includes:

[0014] In response to the first current and the second current satisfying a preset condition, confirming that a sampling moment of the second current is the instant of the DC fault;

[0015] Among them, the first current is the maximum value of the three-phase AC current on the converter transformer valve side before the DC fault; the second current is the three-phase current at the first sampling moment that meets the preset conditions among the three-phase AC current on the converter transformer valve side during the DC fault.

[0016] In some embodiments, the preset conditions include:

[0017] ABS(IV_L1)>k*IVNORMMAX, ABS(IV_L2)>k*IVNORMMAX, ABS(IV_L3)>k*IVNORMMAX;

[0018] Among them, ABS is the absolute value operation; IV_L1 is the valve-side current of the first phase in the second current; IV_L2 is the valve-side current of the second phase in the second current; IV_L3 is the valve-side current of the third phase in the second current; IVNORMMAX is the first current; and k is the proportional coefficient.

[0019] In some embodiments, the step of confirming the first pulse signal word based on the on-current at the moment of the DC fault includes:

[0020] Confirm the marking of the converter valve corresponding to the on-current at the moment of DC fault;

[0021] The first pulse signal word is confirmed based on a mark of a converter valve corresponding to the on-current at the moment of the DC fault.

[0022] In some embodiments, the marking of the converter valve includes a number;

[0023] The step of confirming the first pulse signal word based on the mark of the converter valve corresponding to the on-current at the moment of the DC fault comprises:

[0024] Obtaining the number of the tag;

[0025] Based on the binary encoding rule, sort from low to high, assign 1 to the sort position corresponding to the number, and generate the first pulse signal word.

[0026] In some embodiments, the step of identifying a faulty converter valve based on the first pulse signal word and the second pulse signal word includes:

[0027] Confirm the marking of the converter valve that caused the DC fault:

[0028] Vnum=cpr1^(cpr1&cpr2);

[0029] Wherein, Vnum is the identifier of the converter valve that generates the DC fault; cpr1 is the first pulse signal word; cpr2 is the second pulse signal word; ^ is the bitwise exclusive OR operator; & is the bitwise AND operator;

[0030] The converter valve where the DC fault occurs is identified based on Vnum.

[0031] In some embodiments, the step of identifying the converter valve causing the DC fault based on Vnum includes:

[0032] Vnum is a binary code. Search from the low-order value to the high-order value of Vnum to obtain the position number where the first digit 1 is located. This is the number of the converter valve where the DC fault occurs.

[0033] In some embodiments, the value range of the proportional coefficient satisfies: 1≤k≤2.

[0034] In a second aspect, an embodiment of the present application provides a fault diagnosis system for a short circuit in a converter valve bridge arm of a direct current transmission system, comprising:

[0035] A first module, the first module is used to confirm a first pulse signal word, the first pulse signal word is a pulse signal word at the moment of a DC fault;

[0036] A second module, the second module is used to confirm a second pulse signal word, where the second pulse signal word is a subsequent pulse signal word adjacent to the first pulse signal word based on a commutation sequence of the three-phase current;

[0037] The third module is used to confirm the faulty converter valve based on the first pulse signal word and the second pulse signal word.

[0038] Beneficial effect: Compared with the prior art, the embodiment of the present application provides a fault diagnosis method for a short circuit in a bridge arm of a converter valve in a DC transmission system. The fault diagnosis method for a short circuit in a bridge arm of a converter valve in a DC transmission system of the present application confirms that the corresponding pulse signal word is a first pulse signal word at the moment of the DC fault, and confirms that the subsequent pulse signal word adjacent to the first pulse signal word is a second pulse signal word based on the commutation sequence of the three-phase current; the fault diagnosis method of the present application performs a solution based on the first pulse signal word and the second pulse signal word to obtain a mark of the corresponding converter valve, and confirms the faulty converter valve through the mark; the present application combines the pulse signal word based on the moment of the DC fault with the subsequent pulse signal word based on the commutation sequence, and can quickly locate the faulty converter valve only by processing the pulse signal word, which is conducive to timely handling of the fault.

[0039] An embodiment of the present application provides a fault diagnosis system for a short circuit in a bridge arm of a converter valve in a direct current transmission system, comprising a first module, a second module, and a third module; in the present application, the first module is used to confirm that the pulse signal word at the moment of the direct current fault is a first pulse signal word; the second module is used to confirm that the subsequent pulse signal word adjacent to the first pulse signal word based on the commutation sequence of the three-phase current is a second pulse signal word; the third module is used to confirm the converter valve at the moment of the direct current fault based on the first pulse signal word and the second pulse signal word; the present application combines the pulse signal word based on the moment of the direct current fault with the subsequent pulse signal word based on the commutation sequence, and can quickly locate the faulty converter valve only by processing the pulse signal word, which is conducive to timely handling of the fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A flowchart of the steps of a method for diagnosing a short circuit in a converter valve bridge arm of a DC transmission system provided in an embodiment of the present application;

[0042] Figure 2 A specific flow chart of step 100 in a fault diagnosis method for a short circuit in a converter valve bridge arm of a direct current transmission system provided in an embodiment of the present application;

[0043] Figure 3 A specific flow chart of step 300 in a fault diagnosis method for a short circuit in a converter valve bridge arm of a direct current transmission system provided in an embodiment of the present application;

[0044] Figure 4 A module structure diagram of a fault diagnosis system for a short circuit in a converter valve bridge arm of a direct current transmission system provided in an embodiment of the present application;

[0045] Figure 5 This is a schematic diagram of the structure of the pulsating bridge converter valve in the rectifier station 12;

[0046] Figure 6 This is a schematic diagram of the instantaneous Y-bridge DC fault. The first sub-figure is the three-phase current IVY_L1, IVY_L2, and IVY_L3 on the star side of the valve, and the second sub-figure is the pulse signal word CPRY of the Y-bridge.

[0047] Figure numerals: 1, first module; 2, second module; 3, third module. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0049] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0050] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0051] The DC transmission system includes a converter valve group and a converter valve trigger system. The AC side of the converter valve group is connected to the three-phase AC current, and the DC side of the converter valve group is connected to the DC transmission line. The converter valve trigger system is connected to the control end of the converter valve group and outputs pulse signal words to control the phase change of the converter valve group.

[0052] The present invention addresses DC faults in converter valves and proposes a fault diagnosis method and system for short-circuited converter valve bridge arms in a DC transmission system to identify the specific converter valve causing the DC fault. A six-pulse converter valve is used as an example for illustration below. The invention is applicable to both Y-bridge six-pulse converter valves and D-bridge six-pulse converter valves, and is not limited to two six-pulse converter valves connected in series (i.e., a 12-pulse converter valve) or two 12-pulse converter valves connected in series or in parallel.

[0053] See also Figures 1 to 3 ,as well as Figure 5 and Figure 6The present application provides a fault diagnosis method for a short circuit in a bridge arm of a converter valve in a direct current transmission system. The fault diagnosis method for a short circuit in a bridge arm of a converter valve in a direct current transmission system of the present application confirms that the corresponding pulse signal word is a first pulse signal word at the moment of the direct current fault, and confirms that the subsequent pulse signal word adjacent to the first pulse signal word is a second pulse signal word based on the commutation sequence of the three-phase current; the fault diagnosis method of the present application performs a solution based on the first pulse signal word and the second pulse signal word to obtain a mark of the corresponding converter valve, and confirms the faulty converter valve through the mark; the present application combines the pulse signal word based on the moment of the direct current fault with the subsequent pulse signal word based on the commutation sequence, and can quickly locate the faulty converter valve only by processing the pulse signal word, which is conducive to timely handling of the fault.

[0054] See also Figure 1 In some embodiments, the present application provides a method for diagnosing a short circuit fault in a converter valve bridge arm of a direct current transmission system, which specifically includes the following steps:

[0055] Step 100: Confirm a first pulse signal word, where the first pulse signal word is a pulse signal word at the moment of a DC fault.

[0056] In some embodiments, when confirming the first pulse signal word, if there is a device that records the pulse signal word, such as historical data or data record, the pulse signal word confirming the DC fault moment can be directly read.

[0057] Specifically, the pulse signal words sent by the converter valve trigger system are directly collected. The Y-bridge collects CPRY (Y-bridge pulse signal word), and the D-bridge collects CPRD (D-bridge pulse signal word). When expressed in binary, each bit represents a valve, corresponding to V1 through V6 from lowest to highest. If the converter valve trigger system sends a pulse signal word to a particular converter valve, the corresponding bit is 1. For example, if CPRY = 48, then in binary, 48 = 0x110000, indicating that the control system sends pulse signal words to V5 and V6 of the Y-bridge.

[0058] See also Figure 2 In some embodiments, when confirming the first pulse signal word, if the pulse signal word cannot be directly read, the current conducted at the moment of the DC fault can be confirmed in combination with the valve side current, and then the pulse signal word can be confirmed, which specifically includes the following steps:

[0059] In some embodiments, the relationship between the conductor current and the converter valve may be:

[0060] Phase A positive current conduction - V4 conduction;

[0061] Phase A negative current conduction - V1 conduction;

[0062] Phase B positive current conduction - V6 conduction;

[0063] Phase B negative current conduction - V3 conduction;

[0064] Phase C positive current conduction - V2 conduction;

[0065] Phase C negative current is turned on - V5 is turned on.

[0066] Step 110: Confirm the on-state current at the moment of the DC fault.

[0067] Step 111: Confirm the DC fault moment:

[0068] In response to the first current and the second current satisfying a preset condition, confirming that a sampling moment of the second current is a DC fault moment;

[0069] Among them, the first current is the maximum value of the three-phase AC current on the converter transformer valve side before the DC fault; the second current is the three-phase current at the first sampling moment that meets the preset conditions among the three-phase AC current on the converter transformer valve side during the DC fault.

[0070] Specifically, the three-phase AC current on the valve side of the converter transformer before and after the DC fault is collected: the Y bridge collects IVY_L1, IVY_L2, and IVY_L3, and the D bridge collects IVD_L1, IVD_L2, and IVD_L3, where IVY represents the Y bridge valve side current, IVD represents the D bridge valve side current, and L1, L2, and L3 represent phases A, B, and C, respectively.

[0071] Specifically, the maximum value of the three-phase AC current before the DC fault, that is, the maximum value in the normal operating state, is confirmed to be the first current; the current value at the first sampling moment that meets the preset conditions during the DC fault is confirmed to be the second current, and the sampling moment corresponding to the second current is the moment of the DC fault.

[0072] The preconditions include:

[0073] ABS(IV_L1)>k*IVNORMMAX, ABS(IV_L2)>k*IVNORMMAX, ABS(IV_L3)>k*IVNORMMAX;

[0074] Among them, ABS is the absolute value operation; IV_L1 is the valve-side current of the first phase in the second current; IV_L2 is the valve-side current of the second phase in the second current; IV_L3 is the valve-side current of the third phase in the second current; IVNORMMAX is the first current; k is the proportional coefficient, and the value range of the proportional coefficient satisfies: 1≤k≤2.

[0075] In some embodiments, the value of the proportional coefficient can be any specific value selected from 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, or any value in the range formed by combining any two values.

[0076] Specifically, in the Y bridge, the preset conditions may be:

[0077] ABS(IVY_L1)>k*IVYNORMMAX, ABS(IVY_L2)>k*IVYNORMMAX, ABS(IVY_L3)>k*IVYNORMMAX;

[0078] Among them, IVY_L1 is the valve-side current of phase A in the second current of the Y-bridge; IVY_L2 is the valve-side current of phase B in the second current of the Y-bridge; IVY_L3 is the valve-side current of phase C in the second current of the Y-bridge; IVYNORMMAX is the first current of the Y-bridge, IVYNORMMAX=max{IVYNORMA, IVYNORMB, IVYNORMC}, IVYNORMA, IVYNORMB, IVYNORMC are the maximum values ​​of phase A, phase B and phase C in the three-phase current of the Y-bridge before the DC fault.

[0079] Specifically, in the D bridge, the preset conditions may be:

[0080] ABS(IVD_L1)>k*IVDNORMMAX, ABS(IVD_L2)>k*IVDNORMMAX, ABS(IVD_L3)>k*IVDNORMMAX;

[0081] Among them, IVD_L1 is the valve-side current of phase A in the second current of the D bridge; IVD_L2 is the valve-side current of phase B in the second current of the D bridge; IVD_L3 is the valve-side current of phase C in the second current of the D bridge; IVDNORMMAX is the first current of the D bridge, IVDNORMMAX=max{IVDNORMA, IVDNORMB, IVDNORMC}, IVDNORMA, IVDNORMB, IVDNORMC are the maximum values ​​of phase A current, phase B current and phase C current in the three-phase current of the D bridge before the fault.

[0082] Step 112: Confirm the conduction current.

[0083] Specifically, at the moment of a DC fault, the current being conducted is the negative current of phase A and the positive current of phase B.

[0084] Step 120: confirming the first pulse signal word based on the on-current at the moment of the DC fault.

[0085] Step 121: Confirm the mark of the converter valve corresponding to the on-current at the moment of the DC fault.

[0086] Specifically, at the moment of the DC fault, the current being conducted is the negative current of phase A and the positive current of phase B, and it is confirmed that the corresponding marks of the converter valves are V1 and V6.

[0087] Step 122: confirming the first pulse signal word based on the mark of the converter valve corresponding to the on-current at the moment of the DC fault.

[0088] In some embodiments, the markings of the diverter valves include numbers, such as numbers 1-6 from V1-V6.

[0089] Step 1221: Get the number of the tag.

[0090] Specifically, based on the markings V1 and V6 of the converter valves, they are numbered 1 and 6.

[0091] Step 1222: Based on the binary encoding rule, sort from low to high, assign 1 to the sort position corresponding to the number, and generate the first pulse signal word.

[0092] Specifically, when the numbers are 1 and 6, in the binary number, search from the low position to the high position, assign 1 to the first position and assign 1 to the sixth position, then the corresponding binary number is 0x100001, and the binary number is converted to decimal number 33, then the corresponding first pulse signal word cpry1 of the Y bridge is 33.

[0093] Step 200: confirming a second pulse signal word, where the second pulse signal word is a subsequent pulse signal word adjacent to the first pulse signal word based on a commutation sequence of three-phase current.

[0094] Specifically, based on the commutation sequence of the three-phase current, the next pulse signal word, ie, the second pulse signal word cpry2=3 of the Y bridge, is confirmed.

[0095] See also Figure 3 , step 300: confirming the faulty converter valve based on the first pulse signal word and the second pulse signal word.

[0096] Step 310: Confirm the flag of the converter valve that has generated the DC fault:

[0097] Vnum=cpr1^(cpr1&cpr2);

[0098] Wherein, Vnum is the identifier of the converter valve that generates the DC fault; cpr1 is the first pulse signal word; cpr2 is the second pulse signal word; ^ is the bitwise exclusive OR operator; and & is the bitwise AND operator.

[0099] Step 320: Identify the converter valve that has caused the DC fault based on the flag of the converter valve that has caused the DC fault:

[0100] Vnum is a binary code. Search from the low-order value to the high-order value of Vnum to obtain the position number where the first digit 1 is located. This is the number of the converter valve that causes the DC fault.

[0101] Specifically, Vnum=cpry1^(cpry1&cpry2)=33^(33&3)=33^1=0x100000, and the first 1 is located at the sixth position when searching from low to high. Therefore, the valve with DC fault is the V6 commutation valve of the Y bridge.

[0102] See also Figure 5 and Figure 6 The following describes in detail the fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system provided by the embodiment of the present application in combination with a detailed case:

[0103] Taking the converter valve group bridge arm short-circuit fault as an example, before diagnosis, it is unknown whether the fault occurs in pole 1 or pole 2, and whether it is in the Y bridge or D bridge. Therefore, the Y bridge and D bridge of poles 1 and 2 are diagnosed separately, and the non-fault information is omitted. Only the faulty Y bridge information of pole 2 is displayed:

[0104] According to the fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system provided by an embodiment of the present application, the valve side current is first obtained, and the DC fault instant is calculated, such as Figure 2 As shown in the mark, there are two methods to obtain the first pulse signal word:

[0105] Method A: Get directly, such as Figure 2 The value of the first pulse signal word CPRY is marked as cpry1=33.

[0106] Method B: Through calculation, it is found that the current being conducted at the moment of the DC fault is the negative current of phase A and the positive current of phase B. The corresponding converter valves are V1 and V6 respectively. Therefore, the corresponding first pulse signal word CPRY value should be cpry1=33.

[0107] Then, following the commutation sequence, the value of the next pulse signal word CPRY is cpry2 = 3. Solving for the commutation valve with the bridge arm short circuit: Vnum = cpry1^(cpry1 & cpry2) = 33^(33 & 3) = 33^1 = 0x100000. Searching from low to high, the first 1 is in the sixth position, so the valve with the bridge arm short circuit is the V6 commutation valve of the Y bridge.

[0108] The valve group bridge arm short-circuit process is as follows: before the fault, CPRY=33, that is, V1V6 is turned on. At this time, a bridge arm short-circuit fault occurs in V6, and the valve side current increases. Originally, V6 would be commutated to V2 (CPRY=3), but due to the V6 bridge arm short-circuit, the current on V6 could not be cut off, resulting in V2 being unable to turn on and the commutation unable to be completed. The fault current continues to increase, and eventually the protection action trips.

[0109] See also Figure 4In some embodiments, the present application provides a fault diagnosis system for a short circuit in a converter valve bridge arm of a direct current transmission system, comprising:

[0110] The first module 1 is used to confirm the first pulse signal word, which is the pulse signal word at the moment of the DC fault;

[0111] The second module 2 is used to confirm the second pulse signal word, the second pulse signal word is a subsequent pulse signal word adjacent to the first pulse signal word based on the commutation sequence of the three-phase current;

[0112] The third module 3 is used to confirm the faulty converter valve based on the first pulse signal word and the second pulse signal word.

[0113] In some embodiments, the first module 1 is specifically configured to:

[0114] Confirm the on-state current at the moment of DC fault;

[0115] The first pulse signal word is confirmed based on the on-current at the moment of the DC fault.

[0116] In some embodiments, the first module 1 is specifically configured to:

[0117] In response to the first current and the second current satisfying a preset condition, confirming that a sampling moment of the second current is a DC fault moment;

[0118] Among them, the first current is the maximum value of the three-phase AC current on the converter transformer valve side before the DC fault; the second current is the three-phase current at the first sampling moment that meets the preset conditions among the three-phase AC current on the converter transformer valve side during the DC fault.

[0119] In some embodiments, the preset conditions include:

[0120] ABS(IV_L1)>k*IVNORMMAX, ABS(IV_L2)>k*IVNORMMAX, ABS(IV_L3)>k*IVNORMMAX;

[0121] Among them, ABS is the absolute value operation; IV_L1 is the valve-side current of the first phase in the second current; IV_L2 is the valve-side current of the second phase in the second current; IV_L3 is the valve-side current of the third phase in the second current; IVNORMMAX is the first current; k is the proportional coefficient, and the value range of the proportional coefficient satisfies: 1≤k≤2.

[0122] In some embodiments, the first module 1 is specifically configured to:

[0123] Confirm the marking of the converter valve corresponding to the on-current at the moment of DC fault;

[0124] The first pulse signal word is confirmed based on the mark of the converter valve corresponding to the on-current at the moment of the DC fault.

[0125] In some embodiments, the third module 3 is specifically used to:

[0126] Confirm the marking of the converter valve that caused the DC fault:

[0127] Vnum=cpr1^(cpr1&cpr2);

[0128] Wherein, Vnum is the identifier of the converter valve generating the DC fault; cpr1 is the first pulse signal word; cpr2 is the second pulse signal word; ^ is the bitwise exclusive OR operator; & is the bitwise AND operator;

[0129] The converter valve causing the DC fault is identified based on the flag of the converter valve causing the DC fault.

[0130] In some embodiments, the third module 3 is specifically used to:

[0131] Vnum is a binary code. Search from the low-order value to the high-order value of Vnum to obtain the position number where the first digit 1 is located. This is the number of the converter valve that causes the DC fault.

[0132] In some embodiments, an embodiment of the present application provides a fault diagnosis device for a short circuit in a converter valve bridge arm of a DC transmission system, comprising a processor and a memory, wherein the memory stores a computer program executable by the processor, and when the processor executes the computer program, the fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system of the embodiment of the present application is implemented.

[0133] In some embodiments, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the fault diagnosis method for short circuit of a converter valve bridge arm in a direct current transmission system according to an embodiment of the present application is executed.

[0134] The present application has described in detail the fault diagnosis method and system for a short circuit in a converter valve bridge arm of a direct current transmission system provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only intended to help understand the method and core concept of the present application. At the same time, for those skilled in the art, according to the concept of the present application, there may be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present application.

Claims

1. A fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system, characterized in that: The DC power transmission system includes a converter valve group and a converter valve triggering system. The AC side of the converter valve group is connected to a three-phase AC current, and the DC side of the converter valve group is connected to a DC transmission line. The converter valve triggering system is connected to a control terminal of the converter valve group to output a pulse signal word to perform phase switching control on the converter valve group. The method comprises: confirming a first pulse signal word, where the first pulse signal word is a pulse signal word at the moment of a DC fault; confirming a second pulse signal word, where the second pulse signal word is a subsequent pulse signal word adjacent to the first pulse signal word based on a commutation sequence of the three-phase current; A faulty converter valve is identified based on the first pulse signal word and the second pulse signal word.

2. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC power transmission system according to claim 1, characterized in that: The step of confirming the first pulse signal word comprises: confirming the on-state current at the instant of the DC fault; The first pulse signal word is confirmed based on the on-current at the moment of the DC fault.

3. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system according to claim 1, characterized in that: The steps of confirming the DC fault moment include: In response to the first current and the second current satisfying a preset condition, confirming that a sampling moment of the second current is the instant of the DC fault; Among them, the first current is the maximum value of the three-phase AC current on the converter transformer valve side before the DC fault; the second current is the three-phase current at the first sampling moment that meets the preset conditions among the three-phase AC current on the converter transformer valve side during the DC fault.

4. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system according to claim 3, characterized in that: The preset conditions include: ABS(IV_L1)>k*IVNORMMAX, ABS(IV_L2)>k*IVNORMMAX, ABS(IV_L3)>k*IVNORMMAX; Among them, ABS is the absolute value operation; IV_L1 is the valve-side current of the first phase in the second current; IV_L2 is the valve-side current of the second phase in the second current; IV_L3 is the valve-side current of the third phase in the second current; IVNORMMAX is the first current; and k is the proportional coefficient.

5. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC power transmission system according to claim 2, characterized in that: The step of confirming the first pulse signal word based on the on-current at the moment of the DC fault comprises: Confirm the marking of the converter valve corresponding to the on-current at the moment of DC fault; The first pulse signal word is confirmed based on a mark of a converter valve corresponding to the on-current at the instant of the DC fault.

6. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system according to claim 5, characterized in that: The marking of the converter valve includes a number; The step of confirming the first pulse signal word based on the mark of the converter valve corresponding to the on-current at the moment of the DC fault comprises: Obtaining the number of the tag; Based on the binary encoding rule, sort from low to high, assign 1 to the sort position corresponding to the number, and generate a first pulse signal word.

7. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC transmission system according to claim 1, characterized in that: The step of identifying a faulty converter valve based on the first pulse signal word and the second pulse signal word includes: Confirm the marking of the converter valve that caused the DC fault: Vnum=cpr1^(cpr1&cpr2); Wherein, Vnum is the identifier of the converter valve that generates the DC fault; cpr1 is the first pulse signal word; cpr2 is the second pulse signal word; ^ is the bitwise exclusive OR operator; & is the bitwise AND operator; The converter valve where the DC fault occurs is identified based on the flag of the converter valve where the DC fault occurs.

8. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC power transmission system according to claim 7, characterized in that: The step of identifying the converter valve causing the DC fault based on the mark of the converter valve causing the DC fault includes: Vnum is a binary code. Search from the low-order value to the high-order value of Vnum to obtain the position number where the first digit 1 is located. This is the number of the converter valve where the DC fault occurs.

9. The fault diagnosis method for a short circuit in a converter valve bridge arm of a DC power transmission system according to claim 4, characterized in that: The value range of the proportional coefficient satisfies: 1≤k≤2.

10. A fault diagnosis system for short circuit of converter valve bridge arm in a DC transmission system, characterized in that: include: A first module (1), the first module (1) is used to confirm a first pulse signal word, the first pulse signal word being a pulse signal word at the moment of a DC fault; A second module (2), the second module (2) is used to confirm a second pulse signal word, the second pulse signal word being a subsequent pulse signal word adjacent to the first pulse signal word based on a commutation sequence of three-phase current; A third module (3) is used to confirm a faulty converter valve based on the first pulse signal word and the second pulse signal word.

Images