Method and device for detecting phase failure of starting standby transformer and electronic equipment

Abstract

The application discloses a kind of starting spare transformer phase failure detection methods, comprising: measuring the high voltage side three-phase current and three-phase voltage of starting spare transformer;Based on the three-phase current and three-phase voltage, the positive sequence current, zero sequence current, positive sequence voltage and zero sequence voltage are calculated using symmetric component method;Determine whether the amplitude of the zero sequence current exceeds the zero sequence current threshold, yes, determine that phase failure has occurred, otherwise determine that no phase failure has occurred;In response to determining that phase failure has occurred, further determine the phase of the phase failure according to the amplitude of the zero sequence current and the positive sequence current and the angle relationship between the zero sequence current and the positive sequence voltage.Due to the adoption of the technical scheme, phase failure and phase-to-ground fault can be effectively identified under the condition of transformer no-load and load.

Description

Technical Field

[0001] This invention relates to the field of protection and monitoring of transformer systems, and more specifically to methods, devices, and electronic equipment for detecting phase loss faults in the standby transformer system of a power plant. Background Technology

[0002] In power systems, non-full-phase operation caused by various reasons can lead to generator overheating or burnout, resulting in abnormalities in the power plant's auxiliary power system. This not only represents a significant loss for the power plant but also poses a great threat to the safe operation of the power system. Therefore, how to prevent non-full-phase operation accidents in the power system must be given our attention.

[0003] In its 2015 experience feedback report (SOER 2015-1 Safety Challenges from Open Phase Events), the World Association of Nuclear Operators (WANO) highlighted several phase loss incidents at nuclear power plants and their serious consequences, hoping to draw attention to these incidents within the industry and develop corresponding safety precautions.

[0004] For example, on January 30, 2012, at the Byron Nuclear Power Plant Unit 2 in the United States, a lead wire fell off the porcelain bushing of the 345kV switchyard, causing a high-resistance ground fault on the high-voltage side of the start-up standby transformer (referred to as the "Station Auxiliary Transformer" in nuclear power plants). This fault caused single-phase C-phase disconnections in two auxiliary transformers, ultimately leading to a reactor shutdown and damage to the auxiliary transformers. Other units such as Bruce A Unit 1, Forsmark Unit 3, and Vandellos Unit 2 have also experienced phase-loss faults of varying severity in recent years, triggering a series of incidents and seriously threatening the safe operation of nuclear power plants. For transformers with Ynd connection, when a phase-loss fault occurs under no-load or light-load conditions, the transformer voltage shows no abnormality; the fault can only be diagnosed through current.

[0005] A patent from Korea Hydro & Nuclear Power Co., Ltd., entitled "CN201480017545.1 Device for Detecting Phase Loss in Connection Line of Backup Transformer in Nuclear Power Plant Using Rogowski Coil," mentions detecting the current on the Y-connection line of the primary side of the backup transformer using a Rogowski coil to reflect a phase loss fault in the backup transformer. However, this method cannot identify the phase that experienced the phase loss fault, nor can it distinguish whether it is a phase loss grounding fault. Furthermore, a patent from Nanjing NARI Relay Protection & Automation Co., Ltd., entitled "201810139589.1 A Phase Loss Detection Method for Start-up Backup Transformer Based on Optical CT," uses optical CT to detect the three-phase current on the primary side of the backup transformer to reflect a phase loss fault. This method is only applicable to phase loss faults near the high-voltage side of the transformer. When a phase loss fault or a phase loss grounding fault occurs at the far end of the transformer connection line, it cannot effectively distinguish between them, thus having significant limitations. Summary of the Invention

[0006] The purpose of this invention is to propose a method for detecting phase loss faults in a standby transformer, so as to effectively identify phase loss faults or phase loss-to-ground faults, and to identify the phase of the phase loss fault.

[0007] To achieve the above objectives, this application adopts the following technical solution:

[0008] The first aspect of this application proposes a method for detecting phase loss in a standby transformer, comprising:

[0009] Measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer.

[0010] Based on the three-phase current and three-phase voltage, the positive-sequence current, zero-sequence current, positive-sequence voltage and zero-sequence voltage are calculated using the symmetrical component method.

[0011] Determine whether the amplitude of the zero-sequence current exceeds the zero-sequence current threshold. If it does, determine that a phase loss fault has occurred; otherwise, determine that no phase loss fault has occurred.

[0012] In response to the determination that a phase loss fault has occurred, the phase of the phase loss fault is further determined based on the magnitude of the zero-sequence current and the positive-sequence current, as well as the angle relationship between the zero-sequence current and the positive-sequence voltage.

[0013] According to some embodiments, the above-mentioned method for detecting phase loss of standby transformers further includes: in response to determining that a phase loss fault has occurred, calculating the grounding resistance through the phasor relationship between zero-sequence current and positive-sequence voltage.

[0014] According to some embodiments, the above-mentioned method for detecting phase loss of standby transformers further includes: in response to determining that a phase loss fault has occurred, issuing an alarm signal or tripping after a set delay.

[0015] According to some embodiments, the CT and PT used to measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer have sufficient accuracy under no-load and light-load conditions.

[0016] According to some embodiments, the zero-sequence current threshold is a fixed threshold that must be greater than the amplitude of the zero-sequence unbalanced current measured on site.

[0017] According to some embodiments, the zero-sequence current threshold is the larger of a fixed threshold and a floating threshold. The fixed threshold needs to be greater than the amplitude of the zero-sequence unbalanced current measured on-site, and the floating threshold is... Where k1 is a coefficient in the range of 0 to 1. This represents the positive sequence current amplitude.

[0018] According to some embodiments, the method for determining the phase of a phase loss fault based on the magnitudes of the zero-sequence current and the positive-sequence current, as well as the angular relationship between the zero-sequence current and the positive-sequence voltage, includes:

[0019] Step 4.1: Compare the zero-sequence current amplitude. and positive sequence current amplitude Determine the amplitude of zero-sequence current Is it less than Where k2 is a coefficient in the range of 1 to 2; if so, proceed to step 4.2; otherwise, jump to step 4.3.

[0020] Step 4.2: Compare the magnitudes of the three-phase currents. The phase with the smallest current magnitude is the faulty phase.

[0021] Step 4.3: Calculate the phase components of the zero-sequence current in each phase. and the phase components of each phase positive sequence voltage The calculation method is as follows:

[0022]

[0023]

[0024] In the formula It is the zero-sequence current. It is a positive sequence current. This refers to the phase component of the positive sequence current in phase A. This refers to the phase component of the positive sequence current in phase B. This refers to the phase component of the positive sequence current in phase C. It is a positive sequence voltage. This represents the phase component of the positive sequence voltage of phase A. This refers to the phase component of the positive sequence voltage of phase B. This refers to the positive sequence voltage phase component of phase C;

[0025] Calculate the phase components of the zero-sequence current in each phase. and the corresponding positive sequence voltage phase components The angle between the components is denoted as θ. a θ b θ c As shown in the following formula, where Ang represents the phasor angle calculation operator, and θ a θ b θ c Reduced to the range of -360° to 0°;

[0026]

[0027] If θ a satisfy The faulty phase is phase A;

[0028] If θ b satisfy The faulty phase is phase B;

[0029] If θ c satisfy The faulty phase is phase C, where The angle value is within the range of 0° to 10°.

[0030] According to some embodiments, the grounding resistance is calculated using the phasor relationship between zero-sequence current and positive-sequence voltage, including:

[0031] Step 4.2 further includes: the grounding resistance is infinite, that is, no grounding has occurred;

[0032] Step 4.3 further includes: calculating the grounding resistance of the fault phase based on the zero-sequence current phase component and the positive-sequence voltage phase component of the fault phase, using the following specific calculation formula:

[0033]

[0034] In the formula, m is the faulty phase, and R ef Let Re be the grounding resistance, and Re be the real part operator.

[0035] The second aspect of this application discloses a phase loss detection device for starting a standby transformer, comprising:

[0036] The measurement unit is used to measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer.

[0037] The calculation unit is used to calculate the positive sequence current, zero sequence current, positive sequence voltage, and zero sequence voltage based on the three-phase current and three-phase voltage using the symmetrical component method.

[0038] The fault determination unit is used to determine whether the amplitude of the zero-sequence current exceeds the zero-sequence current threshold. If it does, it determines that a phase loss fault has occurred; otherwise, it determines that no phase loss fault has occurred.

[0039] The phase identification unit is used to determine the phase of the phase failure in response to the determination that a phase failure has occurred, based on the magnitude of the zero-sequence current and the positive-sequence current, as well as the angle relationship between the zero-sequence current and the positive-sequence voltage.

[0040] According to some embodiments, the above-mentioned standby transformer phase failure detection device further includes: a grounding resistance calculation unit, used to calculate the grounding resistance through the phasor relationship between zero-sequence current and positive-sequence voltage in response to the determination that a phase failure has occurred.

[0041] A third aspect of this application discloses an electronic device, comprising: a processor; and a memory storing computer instructions that, when executed by the processor, cause the processor to perform the aforementioned method for detecting phase loss in a standby transformer.

[0042] The fourth aspect of this application proposes a non-transient computer storage medium storing a computer program that, when executed by multiple processors, causes the processors to execute the aforementioned method for detecting phase loss in a standby transformer.

[0043] Compared with the prior art, the beneficial effects of this application are: by analyzing the amplitude and angle of the current and voltage sequence components on the high-voltage side of the start-up standby transformer, this application can effectively identify single-phase phase failure and phase-to-ground failure on the start-up standby transformer and the remote connection line under no-load and load conditions, and can identify the phase of the phase failure. Attached Figure Description

[0044] Figure 1 This is a schematic flowchart of a method for detecting phase loss in a standby transformer according to an embodiment of this application.

[0045] Figure 2 This is a typical application wiring diagram provided for an embodiment of this application.

[0046] Figure 3 This is a schematic diagram of another method for detecting phase loss in a standby transformer according to an embodiment of this application.

[0047] Figure 4 This is a schematic diagram of another standby transformer phase loss detection device according to an embodiment of this application.

[0048] Figure 5 This diagram illustrates the structure of an electronic device provided in this application. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings.

[0050] Because non-full-phase operation of transformers can lead to overheating or burnout of equipment, causing losses and safety threats to the power system, existing phase loss detection technologies may not be effective in identifying faults under specific operating conditions, or may be unable to identify the faulty phase. Therefore, this application proposes a method for detecting phase loss when starting a standby transformer, such as... Figure 1 The steps shown are as follows:

[0051] S100. Measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer.

[0052] The three-phase current and three-phase voltage on the high-voltage side are collected by current transformers and voltage transformers installed on the high-voltage side of the standby transformer. The three-phase current phasors are denoted as follows: The three-phase voltage phasors are respectively denoted as...

[0053] The CTs and PTs used to measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer have sufficient accuracy under no-load and light-load conditions.

[0054] S200. Based on the three-phase current and three-phase voltage, calculate the positive sequence current, zero sequence current, positive sequence voltage and zero sequence voltage using the symmetrical component method.

[0055] Based on the three-phase current on the high-voltage side of the standby transformer and three-phase voltage The positive-sequence and zero-sequence components of current and voltage are calculated using the symmetrical component method to obtain the positive-sequence current. Zero-sequence current Positive sequence voltage and zero sequence voltage

[0056]

[0057]

[0058]

[0059]

[0060] In the formula

[0061] 300. Determine whether the amplitude of the zero-sequence current exceeds the zero-sequence current threshold. If yes, determine that a phase loss fault has occurred and proceed to step S400. Otherwise, determine that no phase loss fault has occurred.

[0062] In some embodiments, the zero-sequence current threshold is a fixed threshold that must be greater than the amplitude of the zero-sequence unbalanced current measured on-site.

[0063] In some embodiments, the zero-sequence current threshold is the larger of a fixed threshold and a floating threshold. The fixed threshold must be greater than the field-measured amplitude of the zero-sequence unbalanced current, and the floating threshold is... Where k1 is a coefficient in the range of 0 to 1. This represents the positive sequence current amplitude.

[0064] S400. Determine the phase that has experienced a phase loss fault based on the magnitude of the zero-sequence current and the positive-sequence current, as well as the angle relationship between the zero-sequence current and the positive-sequence voltage.

[0065] In some embodiments, determining the phase of a phase loss fault specifically includes the following steps:

[0066] S401, Compare zero-sequence current amplitude and positive sequence current amplitude Determine the amplitude of zero-sequence current Is it less than Where k2 is a coefficient in the range of 1 to 2; if so, proceed to step 4.2; otherwise, jump to step 4.3.

[0067] S402. Compare the magnitudes of the three-phase currents. The phase with the smallest current magnitude among the three phases is the faulty phase.

[0068] S403, Calculate the phase components of the zero-sequence current in each phase. and the phase components of each phase positive sequence voltage The calculation method is as follows:

[0069]

[0070]

[0071] In the formula It is the zero-sequence current. It is a positive sequence current. This refers to the phase component of the positive sequence current in phase A. This refers to the phase component of the positive sequence current in phase B. This refers to the phase component of the positive sequence current in phase C. It is a positive sequence voltage. This represents the phase component of the positive sequence voltage of phase A. This refers to the phase component of the positive sequence voltage of phase B. This refers to the positive sequence voltage phase component of phase C;

[0072] Calculate the phase components of the zero-sequence current in each phase. and the corresponding positive sequence voltage phase components The angle between the components is denoted as θ. a θb θ c As shown in the following formula, where Ang represents the phasor angle calculation operator, and θ a θ b θ c Reduced to the range of -360° to 0°;

[0073]

[0074] If θ a satisfy The faulty phase is phase A;

[0075] If θ b satisfy The faulty phase is phase B;

[0076] If θ c satisfy The faulty phase is phase C, where The angle value is within the range of 0° to 10°.

[0077] like Figure 2 Some of the embodiments shown also include:

[0078] In response to the determination that a phase loss fault has occurred, the grounding resistance is further calculated using the phasor relationship between zero-sequence current and positive-sequence voltage.

[0079] In some embodiments, calculating the grounding resistance using the phasor relationship between zero-sequence current and positive-sequence voltage specifically includes:

[0080] Step S402 also includes: the grounding resistance is infinite, that is, no grounding has occurred;

[0081] Step S403 further includes: calculating the grounding resistance of the fault phase based on the zero-sequence current phase component and the positive-sequence voltage phase component of the fault phase, using the following specific calculation formula:

[0082]

[0083] In the formula, m is the faulty phase, and R ef Let Re be the grounding resistance, and Re be the real part operator.

[0084] In some embodiments, in response to the determination that a phase loss fault has occurred, an alarm signal is issued or a trip is initiated after a set delay. The set value of the delay ranges from 0.1s to 30.0s, and is preferably 10s.

[0085] The following is combined Figure 2The wiring diagram shown is a typical application of a 220kV start-up standby transformer system in a nuclear power plant, which will be used to specifically introduce the phase-loss fault detection method for the start-up standby transformer in this application. The main electrical wiring diagram, the schematic diagram of phase-loss fault detection for the start-up standby transformer, and the fault point are attached. Figure 2 As shown. The standby transformer is a three-phase, three-winding transformer with a Yn / D-11 / D-11 connection. Phase-loss fault detection is achieved by measuring the three-phase current and three-phase voltage on the high-voltage side. (See diagram.) Figure 3 The specific steps for detecting a phase-loss fault on the high-voltage side of a nuclear power plant's start-up standby transformer are as follows:

[0086] (1) Measure the three-phase current on the high-voltage side of the standby transformer. and three-phase voltage

[0087] (2) Based on the three-phase current on the high-voltage side of the standby transformer and three-phase voltage The positive-sequence and zero-sequence components of current and voltage are calculated using the symmetrical component method to obtain the positive-sequence current. Zero-sequence current Positive sequence voltage and zero sequence voltage

[0088] (3) Determine whether the amplitude of the zero-sequence current exceeds the zero-sequence current threshold. If yes, determine that a phase loss fault has occurred and proceed to step (4). Otherwise, determine that no phase loss fault has occurred.

[0089] In this embodiment, the method for determining phase loss based on the zero-sequence current amplitude is as follows:

[0090]

[0091] In this embodiment, k1 = 0.5, I 0.set =0.2A. Assume the positive sequence current amplitude during monitoring is... If it is 1A, then the zero-sequence current amplitude is... Greater than When the maximum current is max(0.5×1,0.2)=0.5A, it is preliminarily determined that a phase loss fault has occurred.

[0092] (4) Phase identification of phase loss fault and calculation of grounding resistance

[0093] Step 4.1: Compare the zero-sequence current amplitude. and positive sequence current amplitude Determine the amplitude of zero-sequence current Does it satisfy equation (2)? If yes, proceed to step 4.2; otherwise, jump to step 4.3.

[0094]

[0095] Where k2 is a coefficient in the range of 1 to 2, preferably 1.5.

[0096] Step 4.2: Compare the magnitudes of the three-phase currents. The phase with the smallest current magnitude is the faulty phase. The grounding resistance is infinite, meaning no grounding has occurred.

[0097] Step 4.3: Calculate the phase components of the zero-sequence current in each phase. and the phase components of each phase positive sequence voltage The calculation method is as follows:

[0098]

[0099]

[0100] In the formula It is the zero-sequence current. It is a positive sequence current. This refers to the phase component of the positive sequence current in phase A. This refers to the phase component of the positive sequence current in phase B. This refers to the phase component of the positive sequence current in phase C. It is a positive sequence voltage. This represents the phase component of the positive sequence voltage of phase A. This refers to the phase component of the positive sequence voltage of phase B. This refers to the positive sequence voltage phase component of phase C;

[0101] Calculate the phase components of the zero-sequence current in each phase. and the corresponding positive sequence voltage phase components The angle between the components is denoted as θ. a θ b θ c As shown in the following formula, where Ang represents the phasor angle calculation operator, and θ a θ b θ c Reduced to the range of -360° to 0°;

[0102]

[0103] If θ a satisfy The faulty phase is phase A;

[0104] If θ b satisfy The faulty phase is phase B;

[0105] If θ c satisfy The faulty phase is phase C, where The angle value should be within the range of 0° to 10°, with 5° preferred.

[0106] The grounding resistance of the faulted phase is calculated based on the zero-sequence current phase component and the positive-sequence voltage phase component of the faulted phase. The specific calculation formula is as follows:

[0107]

[0108] In the formula, m is the faulty phase, and R ef Let Re be the grounding resistance, and Re be the real part operator.

[0109] (5) In response to the determination that a phase loss fault has occurred, an alarm signal is issued or the circuit breaker is tripped after a set delay. The set delay value ranges from 0.1s to 30.0s, with 10s being preferred.

[0110] The following describes the application of this diagnostic method in different fault scenarios:

[0111] Scenario 1: Figure 2 The phase failure point 1 or phase failure point 2 shown is accompanied by a high-resistance grounding fault. The three-phase voltage and three-phase current are collected, and the calculated sequence component phasors are as follows:

[0112] U a U b U c (kV): 128.25∠-4.43°, 130.40∠-120.20°, 134.46∠119.16°

[0113] U1(kV): 130.98∠-1.80°

[0114] I a I b I c (A): 128.26∠175.57°, 129.94∠174.42°, 126.72∠174.28°

[0115] I1, I0(A): 1.84∠268.21°, 128.30∠174.76°

[0116] If the coefficient k2 in equation (2) is 1.5, the zero-sequence current amplitude is 128.30A, which is much larger than the positive-sequence current amplitude of 1.84A, and does not satisfy equation (2), then it is necessary to calculate the sequence component according to the phase to identify the faulty phase.

[0117] Calculate according to formula (3)

[0118] I 0.a I 0.b I 0.c(A): 128.42∠173.94°, 126.66∠175.13°, 129.84∠175.21°

[0119] U 1.a U 1.b U 1.c : 130.98∠-1.80°, 130.98∠-121.80°, 130.98∠118.20°

[0120] θ a θ b θ c : 175.74°, 296.93°, 57.01°

[0121] Where θ a The faulty phase is therefore identified as phase A within the range of [-185°, -85°].

[0122] Grounding resistance

[0123] Scenario 2: Figure 2 If there is no grounding fault at phase failure point 1 or phase failure point 2, the collected three-phase voltage and three-phase current, and their calculated sequence components are as follows:

[0124] U a U b U c (kV): 132.85∠0°, 132.83∠-120.00°, 132.70∠120°

[0125] U1(kV): 132.79∠-0°

[0126] I a I b I c (A): 3.23∠-120°, 3.23∠180°, 0∠101°

[0127] I1, I0(A): 1.86∠270°, 1.86∠210°

[0128] Let the coefficient k2 in equation (2) be 1.5, and the amplitudes of the zero-sequence current and the positive-sequence current are both 1.86A. Equation (2) is satisfied, so it belongs to the near-end phase failure and has no grounding. According to the amplitude of the three-phase current, the amplitude of phase C is the smallest, so the faulty phase is phase C.

[0129] Scenario 3: Figure 2 The phase failure point 3 shown has a high-resistance grounding fault. The three-phase voltage and three-phase current, and their calculated sequence components are as follows:

[0130] U a Ub U c (kV): 133.21∠0.135°, 134.69∠-120.31°, 133.00∠119.78°

[0131] U1(kV): 133.64∠-0.13°

[0132] I a I b I c (A): 19.32∠154.46°, 22.09∠149.67°, 19.34∠144.86°

[0133] I1, I0(A): 1.88∠269.87°, 20.01∠149.66°

[0134] If the coefficient k2 in equation (2) is 1.5, the zero-sequence current amplitude is 20.01A, which is much larger than the positive-sequence current amplitude of 1.88A, and does not satisfy equation (2), then it is necessary to calculate the sequence component according to the phase to identify the faulty phase.

[0135] Calculate according to formula (3)

[0136] I 0.a I 0.b I 0.c (A): 21.00∠145.32°, 18.17∠149.64°, 20.98∠154.02°

[0137] U 1.a U 1.b U 1.c : 133.64∠-0.13°, 133.64∠-120.13°, 133.64∠119.87°

[0138] θ a θ b θ c : 145.45°, 269.77°, 34.15°

[0139] Where θ b Within the range of [-185°, -85°], the faulty phase is therefore phase B.

[0140] Grounding resistance

[0141] Using the above method, by real-time monitoring of the three-phase current and voltage on the high-voltage side of the nuclear power plant's start-up standby transformer, when the phase loss fault criterion is met, an alarm signal is issued after a set delay to remind the operator to handle the situation promptly.

[0142] This method can solve the problem of difficulty in identifying single-phase open circuit faults and phase-to-ground faults on the high-voltage side of the standby transformer and at the far end of the connecting line under no-load and load conditions, thus improving the safety and reliability of the power plant's standby transformer system.

[0143] Figure 4 The device shown can perform the aforementioned method for detecting phase loss of a standby transformer according to the embodiments of this application.

[0144] like Figure 4 As shown, the standby transformer phase loss detection device 500 is activated, including: a measurement unit 501, a calculation unit 502, a fault determination unit 503, and a phase identification unit 504.

[0145] Measurement unit 501 is used to measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer.

[0146] Calculation unit 502 is used to calculate positive sequence current, zero sequence current, positive sequence voltage and zero sequence voltage based on the three-phase current and three-phase voltage using the symmetrical component method;

[0147] The fault determination unit 503 is used to determine whether the amplitude of the zero-sequence current exceeds the zero-sequence current threshold. If it does, it determines that a phase loss fault has occurred; otherwise, it determines that no phase loss fault has occurred.

[0148] The phase identification unit 504 is used to determine the phase of the phase failure in response to the determination that a phase failure has occurred, based on the magnitude of the zero-sequence current and the positive-sequence current and the angle relationship between the zero-sequence current and the positive-sequence voltage.

[0149] In some embodiments, the standby transformer phase failure detection device 500 further includes a grounding resistance calculation unit 505, which, in response to the determination that a phase failure has occurred, further calculates the grounding resistance through the phasor relationship between zero-sequence current and positive-sequence voltage.

[0150] The device performs functions similar to those described above; other functions are described in the preceding descriptions and will not be repeated here.

[0151] Figure 5 This diagram illustrates the structure of an electronic device provided in this application.

[0152] See Figure 5 , Figure 5 An electronic device is provided, including a processor and a memory. The memory stores computer instructions, which, when executed by the processor, cause the processor to perform the computer instructions to achieve the following: Figure 2 The method and its detailed scheme are shown.

[0153] It should be understood that the above-described device embodiments are merely illustrative, and the device disclosed in this invention can be implemented in other ways. For example, the division of units / modules described in the above embodiments is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units, modules, or components may be combined, integrated into another system, or some features may be ignored or not executed.

[0154] Furthermore, unless otherwise specified, the functional units / modules in the various embodiments of the present invention can be integrated into one unit / module, or each unit / module can exist physically separately, or two or more units / modules can be integrated together. The integrated units / modules described above can be implemented in hardware or as software program modules.

[0155] If the integrated unit / module is implemented in hardware, the hardware can be digital circuits, analog circuits, etc. The physical implementation of the hardware structure includes, but is not limited to, transistors, memristors, etc. Unless otherwise specified, the processor or chip can be any suitable hardware processor, such as a CPU, GPU, FPGA, DSP, and ASIC, etc. Unless otherwise specified, the on-chip cache, off-chip memory, and storage can be any suitable magnetic or magneto-optical storage medium, such as resistive random access memory (RRAM), dynamic random access memory (DRAM), static random access memory (SRAM), enhanced dynamic random access memory (EDRAM), high-bandwidth memory (HBM), hybrid memory cube (HMC), etc.

[0156] If the integrated unit / module is implemented as a software program module and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this disclosure. The aforementioned memory includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0157] This application embodiment also provides a non-transitory computer storage medium storing a computer program, which, when executed by multiple processors, causes the processors to perform actions such as... Figure 1 The method and its detailed scheme are shown.

[0158] It should be clearly understood that this application describes how specific examples are formed and used, but this application is not limited to any details of these examples. Rather, based on the teachings of the disclosure of this application, these principles can be applied to many other embodiments.

[0159] Furthermore, it should be noted that the above figures are merely illustrative representations of the processes included in the method according to exemplary embodiments of this application, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0160] Exemplary embodiments of this application have been specifically shown and described above. It should be understood that this application is not limited to the detailed structures, arrangements, or implementation methods described herein; rather, this application is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. A method for detecting phase loss in a standby transformer during startup, characterized in that, include: Measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer. Based on the three-phase current and three-phase voltage, the positive-sequence current, zero-sequence current, positive-sequence voltage and zero-sequence voltage are calculated using the symmetrical component method. Determine whether the amplitude of the zero-sequence current exceeds the zero-sequence current threshold. If it does, determine that a phase loss fault has occurred; otherwise, determine that no phase loss fault has occurred. In response to the determination that a phase loss fault has occurred, the phase of the phase loss fault is further determined based on the magnitude of the zero-sequence current and the positive-sequence current, as well as the angle relationship between the zero-sequence current and the positive-sequence voltage. The method for determining the phase of a phase loss fault based on the magnitudes of the zero-sequence current and the positive-sequence current, as well as the angular relationship between the zero-sequence current and the positive-sequence voltage, includes: Step 4.1, compare the zero sequence current amplitude with the positive sequence current amplitude and determine if the zero sequence current amplitude is less than where is a coefficient in the range 1-2; if yes, go to step 4.2, otherwise jump to step 4.3; Step 4.2: Compare the magnitudes of the three-phase currents. The phase with the smallest current magnitude is the faulty phase. Step 4.3, calculating the phase components of the zero sequence current , , and the phase components of the positive sequence voltage , , , The phase components of the zero-sequence current are calculated respectively , , The phase components of the corresponding phase positive-sequence voltage are calculated respectively , , The included angle between the phase components of the zero-sequence current and the phase components of the corresponding phase positive-sequence voltage is recorded as , , ; If (-180° - φ) < θ < (-90° + φ) < (-90°+φ), the fault phase is A phase; If (-180° - φ) < θ < (-90° + φ) B phase is the fault phase. like Satisfy (-180°-φ) < If the value is less than (-90°+φ), then the faulty phase is phase C, where φ is the angle value within the range of 0° to 10°.

2. The method of claim 1, further comprising: include: In response to the determination that a phase loss fault has occurred, the grounding resistance is further calculated using the phasor relationship between zero-sequence current and positive-sequence voltage.

3. The method for detecting phase loss in a standby transformer as described in claim 1, characterized in that it further includes... include: When a phase loss fault is detected, an alarm signal is issued after a set delay or the circuit breaker is tripped.

4. The method for detecting phase loss in a standby transformer as described in claim 1, characterized in that, The CT and PT used to measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer have sufficient accuracy under no-load and light-load conditions.

5. The method for detecting phase loss in a standby transformer as described in claim 1, characterized in that, The zero-sequence current threshold is a fixed threshold that must be greater than the amplitude of the zero-sequence unbalanced current measured on site.

6. The method for detecting phase loss in a standby transformer as described in claim 1, characterized in that, The zero-sequence current threshold is the larger of a fixed threshold and a floating threshold. The fixed threshold must be greater than the amplitude of the zero-sequence unbalanced current measured on-site. The floating threshold is... ,in, The coefficient is in the range of 0 to 1. This represents the positive sequence current amplitude.

7. The method for detecting phase loss in a standby transformer as described in claim 1, characterized in that, The calculation of the zero-sequence current phase components of each phase , , and the phase components of each phase positive sequence voltage , , The calculation method is as follows: In the formula ; It is the zero-sequence current. It is a positive sequence current. This refers to the phase component of the positive sequence current in phase A. This refers to the phase component of the positive sequence current in phase B. This refers to the phase component of the positive sequence current in phase C. It is a positive sequence voltage. This represents the phase component of the positive sequence voltage of phase A. This refers to the phase component of the positive sequence voltage of phase B. This refers to the positive sequence voltage phase component of phase C; The , , The calculation method is shown in the following formula, where... This represents the phasor angle calculation operator. , , Reduced to the range of -360° to 0°; 。 8. The method for detecting phase loss in a standby transformer as described in claim 7, characterized in that, It also includes calculating the grounding resistance using the phasor relationship between zero-sequence current and positive-sequence voltage, specifically including: Step 4.2 further includes: the grounding resistance is infinite, that is, no grounding has occurred; Step 4.3 further includes: calculating the grounding resistance of the fault phase based on the zero-sequence current phase component and the positive-sequence voltage phase component of the fault phase, using the following specific calculation formula: In the formula, m is the faulty phase. For grounding resistance, Re This is the operator for taking the real part.

9. A phase loss detection device for a standby transformer, characterized in that, include: The measurement unit is used to measure the three-phase current and three-phase voltage on the high-voltage side of the standby transformer. The calculation unit is used to calculate the positive sequence current, zero sequence current, positive sequence voltage, and zero sequence voltage based on the three-phase current and three-phase voltage using the symmetrical component method. The fault determination unit is used to determine whether the amplitude of the zero-sequence current exceeds the zero-sequence current threshold. If it does, it determines that a phase loss fault has occurred; otherwise, it determines that no phase loss fault has occurred. The phase identification unit is used to determine the phase of the phase failure in response to the determination that a phase failure has occurred, based on the magnitude of the zero-sequence current and the positive-sequence current and the angle relationship between the zero-sequence current and the positive-sequence voltage. The method for determining the phase of a phase loss fault based on the magnitudes of the zero-sequence current and the positive-sequence current, as well as the angular relationship between the zero-sequence current and the positive-sequence voltage, includes: Step 4.1: Compare the zero-sequence current amplitude. and positive sequence current amplitude Determine the amplitude of the zero-sequence current Is it less than ,in The coefficient is in the range of 1 to 2; if so, proceed to step 4.2; otherwise, jump to step 4.

3. Step 4.2: Compare the magnitudes of the three-phase currents. The phase with the smallest current magnitude is the faulty phase. Step 4.3: Calculate the phase components of the zero-sequence current in each phase. , , and the phase components of each phase positive sequence voltage , , , Calculate the phase components of the zero-sequence current in each phase separately. , , and the corresponding positive sequence voltage phase components , , The angle between the components is denoted as , , ; like Satisfy (-180°-φ) < If the angle is less than (-90°+φ), then the faulty phase is phase A. like Satisfy (-180°-φ) < If the angle is less than (-90°+φ), then the faulty phase is phase B. like Satisfy (-180°-φ) < If the value is less than (-90°+φ), then the faulty phase is phase C, where φ is the angle value within the range of 0° to 10°.

10. The standby transformer phase failure detection device as described in claim 9, characterized in that it further includes... include: The grounding resistance calculation unit is used to calculate the grounding resistance in response to the determination that a phase loss fault has occurred, by further calculating the grounding resistance through the phasor relationship between zero-sequence current and positive-sequence voltage.

11. An electronic device, characterized in that, include: processor; as well as A memory storing computer instructions that, when executed by the processor, cause the processor to perform the method according to any one of claims 1-8.

12. A non-transitory computer storage medium storing a computer program that, when executed by a plurality of processors, causes the processors to perform the method of any one of claims 1-8.

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