Method, device, electronic device and computer-readable medium for judging open-circuit fault of zero-sequence current loop at neutral point of high-voltage side of transformer

Abstract

Provided are a method, device, electronic device and computer-readable medium for judging an open-circuit fault of a zero-sequence current loop at the neutral point of the high-voltage side of a transformer. The method includes: when the transformer meets the no-load charging condition, collecting a first high-voltage side current, a second high-voltage side current and a neutral point zero-sequence current of the transformer; respectively calculating corresponding first zero-sequence current and second zero-sequence current according to the first high-voltage side current and the second high-voltage side current; taking the neutral point zero-sequence current as a reference, correcting the first zero-sequence current and the second zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current; calculating a first fundamental effective value according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and calculating a second fundamental effective value according to the neutral point zero-sequence current; when the first fundamental effective value is higher than a preset first threshold and the second fundamental effective value is lower than a preset second threshold, judging it as an open-circuit fault. The fault can be judged without external test equipment and changing the secondary circuit.

Description

Technical Field

[0001] The present application relates to the field of relay protection of power systems, and particularly relates to a method, device, electronic device and computer-readable medium for judging an open-circuit fault of a zero-sequence current loop at the neutral point of the high-voltage side of a transformer. Background Art

[0002] In a power system, the electric energy generated by a generator in a power plant is transmitted to the power grid through a main transformer, and the main generator increases the output voltage of the power plant to meet the rated high-voltage requirements of the power grid. Therefore, the safe and stable operation of the main transformer in the power plant is a prerequisite for the stable power generation and full-load power generation of the generator set, and is the key to the reliable operation of the power plant.

[0003] An open-circuit fault of the zero-sequence current loop at the neutral point of the high-voltage side of a transformer is one of the common faults during the operation of the transformer. When an open circuit occurs in the zero-sequence current loop at the high-voltage side neutral point, for example, due to factors such as a missed connection in the sampling loop after maintenance or insulation breakdown caused by line aging, single-phase grounding or relatively serious inter-turn short-circuit faults will occur in the transformer. The zero-sequence protection of the transformer will refuse to operate, resulting in the failure to cut off the fault in time, which is not beneficial to the protected equipment.

[0004] Since the three-phase currents are balanced during the normal operation of the transformer, the current in the zero-sequence current loop at the neutral point of the high-voltage side of the transformer is very small and basically close to zero. Therefore, it is impossible to use the normal working current to reflect whether there is a break in the test loop. Currently, for a transformer in a stopped state, a method of performing a single-phase grounding short-circuit test on the high-voltage side of the transformer is usually used to verify whether the zero-sequence current loop at the neutral point of the high-voltage side of the transformer is normal. This method requires changing the primary circuit and relying on external test equipment to conduct a single grounding short-circuit experiment. Such a test method has complex steps, a long time-consuming and high cost, and will also cause certain damage to the transformer. Summary of the Invention

[0005] Based on this, in order to solve the problems that the test method for judging the fault of the zero-sequence current loop at the neutral point of the high-voltage side of the transformer requires changing the primary circuit and relying on external test equipment, has complex steps, is time-consuming and costly, the present application provides a method, device, electronic device and computer-readable medium for judging an open-circuit fault of the zero-sequence current loop at the neutral point of the high-voltage side of the transformer.

[0006] According to the first aspect of the present application, there is provided a method for judging an open-circuit fault of a zero-sequence current loop at the neutral point of the high-voltage side of a transformer, including:

[0007] The method for judging an open-circuit fault of a zero-sequence current loop at the neutral point of the high-voltage side of a transformer includes:

[0008] When the transformer meets the no-load charging condition, collect the first high-voltage side current, the second high-voltage side current and the zero-sequence current at the neutral point of the transformer;

[0009] Calculate the corresponding first zero-sequence current and second zero-sequence current according to the first high-voltage side current and the second high-voltage side current respectively;

[0010] Taking the neutral-point zero-sequence current as a reference, correct the first zero-sequence current and the second zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current;

[0011] Calculate a first fundamental effective value according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and calculate a second fundamental effective value according to the neutral-point zero-sequence current;

[0012] When the first fundamental effective value is higher than a preset first threshold and the second fundamental effective value is lower than a preset second threshold, it is determined as an open-circuit fault.

[0013] According to some embodiments of the present application, the no-load charging condition includes:

[0014] At the moment when the high-voltage side switch of the transformer changes from off to on and within the first delay period thereafter.

[0015] According to some embodiments of the present application, the range of the first delay period includes: 10 - 60 s.

[0016] According to some embodiments of the present application, the calculating the corresponding first zero-sequence current and second zero-sequence current includes:

[0017] Perform the calculation according to the following formula:

[0018]

[0019] where, i a_h1 (k), i b_h1 (k) and i c_h1 (k) are the three-phase sampling values of the first high-voltage side current respectively; i 3I0_Cal_h1 (k) is the sampling value of the first zero-sequence current; i a_h2 (k), i b_h2 (k) and i c_h2 (k) are the three-phase sampling values of the second high-voltage side current respectively; i 3I0_Cal_h2 (k) is the sampling value of the second zero-sequence current of the transformer; k is the sampling sequence.

[0020] According to some embodiments of the present application, the taking the neutral-point zero-sequence current as a reference, correcting the first zero-sequence current and the second zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current includes:

[0021] Calculate the first corrected zero-sequence current and the second corrected zero-sequence current according to the following formula,

[0022]

[0023] wherein, i3′ I0_Cal_h1 (k) and i3′ I0_Cal_h2 (k) are the first corrected zero-sequence current and the second corrected zero-sequence current respectively; N CT11 、N CT21 and N CT31 are respectively the primary sides of current transformers for collecting the first high-voltage side current, the second high-voltage side current, and the zero-sequence current of the neutral point of the high-voltage side.

[0024] According to some embodiments of the present application, calculating the first fundamental effective value includes: performing a Fourier transform on the sum of the first corrected zero-sequence current and the second corrected zero-sequence current; calculating the second fundamental effective value includes: performing a Fourier transform on the zero-sequence current of the neutral point.

[0025] According to some embodiments of the present application, the first threshold is calculated according to the following formula:

[0026]

[0027] The second threshold is calculated according to the following formula:

[0028]

[0029] wherein, k1 is the first reliability coefficient, k2 is the second reliability coefficient, and I n is the secondary side of the current transformer for detecting the voltage of the neutral zero-sequence point.

[0030] According to some embodiments of the present application, the open-circuit fault judgment method further includes:

[0031] During the second delay after being judged as an open-circuit fault, it is still determined as an open-circuit fault.

[0032] According to some embodiments of the present application, the range of the second delay includes: 20 - 60 ms.

[0033] According to another aspect of the present application, there is provided an open-circuit fault judgment device for the zero-sequence current loop of the neutral point of the high-voltage side of a transformer. The open-circuit fault judgment device may include:

[0034] A current parameter acquisition module, configured to acquire the first high-voltage side current, the second high-voltage side current, and the zero-sequence current of the transformer when the transformer meets the no-load charging condition;

[0035] A current conversion module, configured to calculate corresponding first and second zero-sequence currents according to the first high-voltage side current and the second high-voltage side current respectively; and correct the first zero-sequence current and the second zero-sequence current based on the neutral-point zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current;

[0036] An effective value extraction module, configured to calculate a first fundamental effective value according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and calculate a second fundamental effective value according to the neutral-point zero-sequence current;

[0037] A fault judgment module, configured to judge a break fault when the first fundamental effective value is higher than a preset first threshold and the second fundamental effective value is lower than a preset second threshold.

[0038] According to some embodiments of the present application, the break fault judgment device may further include:

[0039] An air charging judgment module, configured to judge whether the transformer meets the air charging condition.

[0040] According to another aspect of the present application, there is provided an electronic device for judging a break fault in a neutral-point zero-sequence current loop of a transformer high-voltage side, including:

[0041] One or more processors;

[0042] A storage device, configured to store one or more programs;

[0043] When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned break fault judgment method.

[0044] According to another aspect of the present application, there is also provided a computer-readable medium, on which a computer program is stored, and when the program is executed by a processor, the above-mentioned break fault judgment method is implemented.

[0045] The break fault judgment method for the neutral-point zero-sequence current loop of the transformer high-voltage side provided by the present application judges the break fault in the neutral-point zero-sequence current loop of the high-voltage side through the acquisition and conversion of electrical parameters, without the need to add external test equipment and modify the secondary circuit.

[0046] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exceeding the scope of protection required by the present application.

[0048] Figure 1 Shows a schematic diagram of current measurement on each side of a power plant transformer according to an exemplary embodiment of the present application;

[0049] Figure 2 Shows a flowchart of a method for judging open - circuit faults according to an exemplary embodiment of the present application;

[0050] Figure 3 Shows a logic diagram of a method for judging open - circuit faults according to an exemplary embodiment of the present application;

[0051] Figure 4 Shows a block diagram of a device for judging open - circuit faults according to an exemplary embodiment of the present application;

[0052] Figure 5 Shows a block diagram of a device for judging open - circuit faults according to another exemplary embodiment of the present application;

[0053] Figure 6 Shows a block diagram of an electronic device for judging open - circuit faults according to an exemplary embodiment of the present application. Detailed implementation manners

[0054] The following will describe the exemplary embodiments more comprehensively with reference to the drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided to make the present application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the figures denote the same or similar parts, and thus their repeated description will be omitted.

[0055] In addition, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, many specific details are provided to give a full understanding of the embodiments of the present application. However, those skilled in the art will realize that the technical solutions of the present application can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, well - known methods, devices, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the present application.

[0056] It should be understood that although terms such as first and second may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another. Thus, the first component discussed below may be referred to as the second component without departing from the teachings of the concepts of this application. As used herein, the term "and / or" includes any one of the associated listed items and all combinations of one or more of them.

[0057] Those skilled in the art can understand that the drawings are only schematic diagrams of exemplary embodiments and may not be to scale. The modules or processes in the drawings are not necessarily essential for implementing this application and thus cannot be used to limit the protection scope of this application.

[0058] Figure 1 The schematic diagrams of measuring the currents on the high-voltage sides of each power plant transformer according to the exemplary embodiments of this application are shown.

[0059] As Figure 1 shown, the electric energy generated by the generator 100 of the power plant is transmitted to the power grid through the transformer 200. The currents on the high-voltage sides of the transformer are detected by three-phase current transformers. For example, the three-phase currents on the first high-voltage side 210 of the transformer are detected by the three-phase current transformer 211 (CT1), the three-phase currents on the second high-voltage side 220 of the transformer are detected by the three-phase current transformer 221 (CT2), and the zero-sequence current of the neutral point on the high-voltage side 230 of the transformer is detected by the single-phase current transformer 231 (CT3). As Figure 1 shown, F represents the position of the zero-sequence current loop of the neutral point on the high-voltage side of the transformer; 300 represents the current-related node for judging the open-circuit fault of the zero-sequence current loop of the neutral point on the high-voltage side of the transformer. The currents collected by the current transformer 211, the currents collected by the current transformer 221, and the zero-sequence current of the neutral point collected by the current transformer 231 are gathered at the current-related node 300, and the open-circuit fault of the zero-sequence current loop can be judged by calculation and comparison.

[0060] Figure 1 The basic parameters of the transformer shown in n include: the rated capacity S hn is 1200 MVA; the wiring method is YND11, the rated voltage U ln on the high-voltage side is 500 kV, and the rated voltage U

[0061] ln on the low-voltage side is 24 kV; the parameters of the three-phase current transformers include: the ratio of the primary side to the secondary side of the current transformer 211 (CT1) is 2000 A / 1 A; the ratio of the primary side to the secondary side of the current transformer 221 (CT2) is 2000 A / 1 A; the ratio of the primary side to the secondary side of the current transformer 231 (CT3) is 800 A / 1 A. This application does not limit the parameters of the transformer and the current transformers.Since the three-phase currents are almost completely symmetrical during the normal operation of the transformer and the zero-sequence current of the neutral point on the high-voltage side is extremely small, it is difficult for the existing protection methods to discriminate when a break fault occurs at point F. In addition, the method of changing the primary circuit and relying on external test equipment requires a primary grounding short-circuit test, which is complex in steps, time-consuming and costly, and will also cause certain damage to the transformer.

[0062] To solve the above problems, this application intends to provide a method for judging the break fault of the zero-sequence current circuit of the neutral point on the high-voltage side of the transformer. By collecting and converting electrical parameters, the break fault of the zero-sequence current circuit of the neutral point on the high-voltage side can be judged without adding external test equipment and modifying the secondary circuit.

[0063] Figure 2 The flowchart of the break fault judgment method according to an exemplary embodiment of this application is shown.

[0064] As Figure 2 shown, according to the exemplary embodiment of this application, the method for judging the break fault of the zero-sequence current circuit of the neutral point on the high-voltage side of the transformer provided by this application includes the following steps.

[0065] In step S210, when the transformer meets the no-load charging condition, collect the first high-voltage side current, the second high-voltage side current and the zero-sequence current of the neutral point of the transformer.

[0066] During the normal operation of the transformer, the three-phase currents are almost completely symmetrical and the zero-sequence current of the neutral point on the high-voltage side is extremely small. Only when the transformer is charged without load can an unbalanced current be generated, that is, at the moment when the high-voltage side switch of the transformer changes from off to on and within the first delay period afterwards. Therefore, in the break fault judgment method provided by this application, it is first judged whether the transformer meets the no-load charging condition.

[0067] Taking the 3 / 2 breaker connection mode as an example, when both the breaker switch and the side switch in the high-voltage side of the transformer are in the off position, and any one of the switches changes from the off position to the on position, it is determined that the transformer meets the no-load charging condition. Then after the first delay t, the no-load charging condition of the transformer is no longer met. According to some embodiments of this application, the range of the first delay t can be between 10 - 60 s.

[0068] When the transformer meets the no-load charging condition, the first high-voltage side current, the second high-voltage side current and the zero-sequence current of the neutral point of the transformer can be collected respectively through current transformers. For example, through Figure 1 the current transformer 211 (CT1) in it to detect the three-phase currents of the first high-voltage side 210 of the transformer, that is, the first high-voltage side current; through Figure 1 the current transformer 221 (CT2) in it to detect the three-phase currents of the second high-voltage side 220 of the transformer, that is, the second high-voltage side current; through Figure 1The current transformer 231 (CT3) in [it] is used to detect the current on the high-voltage side 230 of the transformer, that is, the zero-sequence current of the neutral point on the high-voltage side.

[0069] In step S220, the corresponding first zero-sequence current and second zero-sequence current are calculated according to the first high-voltage side current and the second high-voltage side current respectively.

[0070] According to the exemplary embodiment of the present application, after the first high-voltage side current sampling value on one side of the high-voltage side of the transformer and the second high-voltage side current sampling value on the second side of the high-voltage side of the transformer are collected by the current transformer, the corresponding first zero-sequence current and second zero-sequence current can be calculated according to the following formula, that is, the self-generated zero-sequence current on one side of the high-voltage side and the self-generated zero-sequence current on the second side of the high-voltage side.

[0071]

[0072] Wherein, i a_h1 (k), i b_h1 (k) and i c_h1 (k) are the three-phase sampling values of the first high-voltage side current on one side of the high-voltage side of the transformer respectively; i 3I0_Cal_h1 (k) is the sampling value of the first zero-sequence current on one side of the high-voltage side; i a_h2 (k), i b_h2 (k) and i c_h2 (k) are the three-phase sampling values of the second high-voltage side current on the second side of the high-voltage side respectively; i 3I0_Cal_h2 (k) is the sampling value of the second zero-sequence current on the second side of the high-voltage side; k is the sampling sequence.

[0073] In step S230, the first zero-sequence current and the second zero-sequence current are corrected based on the zero-sequence current of the neutral point to obtain a first corrected zero-sequence current and a second corrected zero-sequence current.

[0074] Since the parameters of the current transformers for collecting three-phase currents on each high-voltage side of the transformer are different, that is, the primary sides are different, therefore, before judging the fault through the current parameters, it is necessary to correct the zero-sequence currents on each side. After correction, the zero-sequence currents on each side are converted to the same reference, so as to ensure the correctness of subsequent judgment.

[0075] According to the exemplary implementation of the present application, correction is made based on the zero-sequence current of the neutral point, that is, Figure 1 taking the primary side of the current transformer 231 (CT3) that collects the zero-sequence current of the neutral point on the high-voltage side 230 as the reference, adjusting the balance coefficients of the self-generated zero-sequence current on one side of the high-voltage side of the transformer, the self-generated zero-sequence current on the second side of the high-voltage side of the transformer and the zero-sequence current of the neutral point on the high-voltage side, and calculating the first corrected zero-sequence current and the second corrected zero-sequence current according to the following formula.

[0076]

[0077] Among them, i3′ I0_Cal_h1 (k) and i3′ I0_Cal_h2 (k) are respectively the first corrected zero-sequence current (the sampled value of the self-produced corrected zero-sequence current on the high-voltage side of the transformer) and the second corrected zero-sequence current (the sampled value of the self-produced corrected zero-sequence current on the second high-voltage side); i I0_NP (k) and i I ′ 0_NP (k) are respectively the sampled value of the zero-sequence current at the neutral point of the high-voltage side of the transformer and the sampled value of the corrected zero-sequence current at the neutral point of the high-voltage side of the transformer; N CT11 、N CT21 and N CT31 are respectively the primary sides of the current transformers on the first high-voltage side of the transformer, the current transformers on the second high-voltage side, and the zero-sequence current transformer at the neutral point of the high-voltage side. Since, in this application, the correction is based on the primary side of the current transformer 231 (CT3) of the zero-sequence current at the neutral point of the high-voltage side 230, the sampled value i I0_NP (k) of the zero-sequence current at the neutral point of the high-voltage side of the transformer and the sampled value i I ′ 0_NP (k) of the corrected zero-sequence current at the neutral point of the high-voltage side of the transformer are equal.

[0078] N CT11 、N CT21 and N CT31 are the inherent parameters of the current transformers. Taking the current transformers in Figure 1 as an example, the primary side N CT11 of the current transformer 211 (CT1) is 2000A, and the primary side N CT21 of the current transformer 221 (CT2) is 2000A; the primary side N CT31 of the current transformer 231 (CT3) is 800A.

[0079] In step S240, calculate the first fundamental effective value according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and calculate the second fundamental effective value according to the zero-sequence current at the neutral point.

[0080] After taking the zero-sequence current at the neutral point as the reference to correct the first zero-sequence current and the second zero-sequence current to obtain the first corrected zero-sequence current and the second corrected zero-sequence current, the first fundamental effective value and the second fundamental effective value can be obtained through Fourier transform. For example, after performing Fourier transform on the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, the first fundamental effective value is obtained; after performing Fourier transform on the zero-sequence current at the neutral point, the second fundamental effective value is obtained.

[0081] In step S250, when the first fundamental wave effective value is higher than a preset first threshold and the second fundamental wave effective value is lower than a preset second threshold, it is determined as an open - circuit fault.

[0082] Taking the 3 / 2 breaker connection mode of the transformer as an example, the determination condition for the self - generated zero - sequence correction current of the high - voltage side of the transformer to be high is that the fundamental wave effective value (the first fundamental wave effective value) of the self - generated zero - sequence correction current of the high - voltage side of the transformer is higher than the first threshold I 0_set1 , that is:

[0083]

[0084] where I3′ I0_Cal is the first fundamental wave effective value, and I 0_set1 is the first threshold.

[0085] According to some embodiments of the present application, the first threshold I 0_set1 can be determined by the first reliability coefficient k1 and the secondary side of the current transformer on the reference side (that is, the secondary side of the current transformer for detecting the zero - sequence point voltage of the high - voltage side neutral point). Usually, the first reliability coefficient k1 can be taken as 5%. Taking the current transformer in Figure 1 as an example, the secondary side I n is taken as 1A.

[0086] Similarly, the determination condition for the zero - sequence correction current of the high - voltage side neutral point of the transformer to be low is that the fundamental wave effective value (the second fundamental wave effective value) of the zero - sequence correction current of the high - voltage side neutral point of the transformer is lower than the second threshold I 0_set2 , that is:

[0087]

[0088] where I I ′ 0_NP is the second fundamental wave effective value; I 0_set2 is the second threshold.

[0089] According to some embodiments of the present application, the second threshold I 0_set2 can be determined by the second reliability coefficient k2 and the secondary side of the current transformer on the reference side (that is, the secondary side of the current transformer for detecting the zero - sequence point voltage of the high - voltage side neutral point). Usually, the second reliability coefficient k2 can be taken as 2.5%. Taking the current transformer in Figure 1 as an example, the secondary side I n is taken as 1A.

[0090] When the first fundamental wave effective value is higher than the preset first threshold and the second fundamental wave effective value is lower than the preset second threshold, that is, when the following conditions are met, it is determined as an open - circuit fault of the neutral - point zero - sequence circuit:

[0091]

[0092] In addition, according to some other embodiments of the present application, time-delay protection is usually required for the relay protection of the power system. Therefore, in the present application, within the second time-delay T after it is determined as a circuit breaker fault, it is still determined as a circuit breaker fault. Generally, the value range of the second time-delay T can be 20 - 60 ms. In the exemplary embodiment of the present application, the second time-delay T is taken as 40 ms.

[0093] Figure 3 The logic diagram of the circuit breaker fault judgment method according to the exemplary embodiment of the present application is shown.

[0094] As Figure 3 shown, for the circuit breaker fault judgment method provided by the present application, the fault judgment logic process includes:

[0095] Criterion 1: The fundamental wave effective value of the self-generated zero-sequence corrected current on the high-voltage side of the transformer, that is, the first fundamental wave effective value is higher than the preset first threshold value (S310);

[0096] Criterion 2: The fundamental wave effective value of the zero-sequence corrected current at the neutral point of the high-voltage side of the transformer, that is, the second fundamental wave effective value is higher than the preset second threshold value (S320);

[0097] Criterion 3: The transformer meets the no-load charging condition, that is, at the moment when the high-voltage side switch of the transformer changes from the open position to the closed position (S330) and within the first time-delay t thereafter (S340);

[0098] At S340, an "AND gate" logic judgment is performed, that is, it is judged whether the above three criteria are all met. When the "AND gate" logic judgment passes, time-delay protection is performed at S350, and finally a fault judgment action is made at S370, that is, a judgment of a fault in the zero-sequence current circuit of the high-voltage side neutral point is made.

[0099] Figure 4 The block diagram of the circuit breaker fault judgment device according to the exemplary embodiment of the present application is shown.

[0100] On the other hand, according to the present application, a circuit breaker fault judgment device 400 for the zero-sequence current circuit of the high-voltage side neutral point of a transformer is also provided. As Figure 4 shown, according to the exemplary embodiment of the present application, the circuit breaker fault judgment device 400 includes a current parameter acquisition module 420, a current conversion module 430, an effective value extraction module 440, and a fault judgment module 450.

[0101] The current parameter acquisition module 420 can be used to acquire the first high-voltage side current, the second high-voltage side current, and the zero-sequence current of the neutral point of the transformer when the transformer meets the no-load charging condition. For example, through Figure 1 the current transformer 211 (CT1) in Figure 1The current transformer 221 (CT2) in it is used to collect the second high-voltage side current of the second high-voltage side 220 of the transformer; through Figure 1 The current transformer 231 (CT3) in it is used to collect the zero-sequence current of the neutral point of the high-voltage side of the transformer high-voltage side 230.

[0102] The current conversion module 430 can be used to calculate the corresponding first zero-sequence current and second zero-sequence current according to the first high-voltage side current and the second high-voltage side current respectively; and based on the zero-sequence current of the neutral point, correct the first zero-sequence current and the second zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current.

[0103] Since the parameters of the current transformers for collecting currents on each high-voltage side of the transformer are different, that is, the primary sides are different, therefore, before judging the fault through the current parameters, it is necessary to correct the zero-sequence currents on each side. After correction, the zero-sequence currents on each side are converted to the same reference, so as to ensure the correctness of subsequent judgments. In the exemplary embodiment of the present application, the correction is based on the zero-sequence current of the neutral point.

[0104] The effective value extraction module 440 can be used to calculate the first fundamental wave effective value according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and calculate the second fundamental wave effective value according to the zero-sequence current of the neutral point. Through Fourier transform, the corresponding fundamental wave effective value can be obtained.

[0105] The fault judgment module 450 can be used to judge a break fault when the first fundamental wave effective value is higher than a preset first threshold and the second fundamental wave effective value is lower than a preset second threshold.

[0106] Figure 5 Fig. shows a block diagram of a break fault judgment device according to another exemplary embodiment of the present application.

[0107] According to another embodiment of the present application, the break fault judgment device 400 may further include an empty charging judgment module 410. The empty charging judgment module 410 can be used to judge whether the transformer meets the empty charging condition. Taking the 3 / 2 breaker wiring mode as an example, when both the breaker switch and the side switch in the high-voltage side of the transformer are in the off position, and when any one of the switches changes from the off position to the on position, it is determined that the transformer meets the empty charging condition. Then after a first delay t, the empty charging condition of the transformer is no longer met. According to some embodiments of the present application, the range of the first delay t can be between 10 - 60 s.

[0108] Figure 6 Fig. shows a block diagram of an electronic device for break fault judgment according to an exemplary embodiment of the present application.

[0109] The present application also provides an electronic device for judging the open - circuit fault of the zero - sequence current loop at the neutral point of the high - voltage side of a transformer. Figure 6 The display control device 500 is merely an example and should not impose any limitations on the functions and scope of use of the embodiments of the present application.

[0110] As Figure 6 shown, the control device 500 is presented in the form of a general - purpose computing device. The components of the control device 500 may include, but are not limited to: at least one processing unit 510, at least one storage unit 520, a bus 530 connecting different system components (including the storage unit 520 and the processing unit 510), etc.

[0111] The storage unit 520 stores program code, and the program code can be executed by the processing unit 510, so that the processing unit 510 executes the methods according to the above - mentioned various embodiments of the present application described in this specification.

[0112] The storage unit 520 may include a readable medium in the form of a volatile storage unit, such as a random - access storage unit (RAM) 5201 and / or a cache storage unit 5202, and may further include a read - only storage unit (ROM) 5203.

[0113] The storage unit 520 may also include a program / utilities 5204 having a set (at least one) of program modules 5205. Such program modules 5205 include, but are not limited to: an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include the implementation of a network environment.

[0114] The bus 530 may represent one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of the multiple bus structures.

[0115] The electronic device 500 can also communicate with one or more external devices 5001 (such as a touch screen, a keyboard, a pointing device, a Bluetooth device, etc.), and can also communicate with one or more devices that enable a user to interact with the electronic device 500, and / or communicate with any device that enables the electronic device 500 to communicate with one or more other computing devices (such as a router, a modem, etc.). Such communication can be carried out through the input / output (I / O) interface 550. Moreover, the electronic device 500 can also communicate with one or more networks (such as a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through the network adapter 560. The network adapter 560 can communicate with other modules of the electronic device 500 through the bus 530. It should be understood that, although not shown in the figure, other hardware and / or software modules can be used in combination with the electronic device 500, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, etc.

[0116] The embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. At the same time, changes or deformations made by those skilled in the art based on the idea of the present application in terms of the specific implementation manner and application scope of the present application all belong to the protection scope of the present application. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for judging the open - circuit fault of the zero - sequence current loop at the neutral point of the high - voltage side of a transformer, characterized in that, Including: When the transformer meets the no-load charging condition, collect the first high-voltage side current, the second high-voltage side current, and the neutral point zero-sequence current of the transformer; Calculate the corresponding first zero-sequence current and second zero-sequence current according to the first high-voltage side current and the second high-voltage side current respectively, including: Calculate according to the following formula: wherein, i a_h1 (k), i b_h1 (k) and i c_h1 (k) are respectively the three-phase sampling values of the first high-voltage side current; i 3I0_Cal_h1 (k) is the sampling value of the first zero-sequence current; i a_h2 (k), i b_h2 (k) and i c_h2 (k) are respectively the three-phase sampling values of the second high-voltage side current; i 3I0_Cal_h2 (k) is the sampling value of the second zero-sequence current of the transformer; k is the sampling sequence; Using the neutral point zero-sequence current as a reference, correct the first zero-sequence current and the second zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current, including: Calculate the first corrected zero-sequence current and the second corrected zero-sequence current according to the following formula, where, i′ 3I0_Cal_h1 (k) and i′ 3I0_Cal_h2 (k) are the first corrected zero-sequence current and the second corrected zero-sequence current respectively; N CT11 、N CT21 and N CT31 are the primary side currents of the current transformers that collect the first high-voltage side current, the second high-voltage side current, and the zero-sequence current of the high-voltage side neutral point respectively; Calculate the first fundamental effective value according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and calculate the second fundamental effective value according to the neutral point zero-sequence current; When the first fundamental effective value is higher than a preset first threshold and the second fundamental effective value is lower than a preset second threshold, it is judged as an open-circuit fault.

2. The circuit breakage fault determination method according to claim 1, wherein The no-load charging condition includes: At the moment when the high-voltage side switch of the transformer changes from off to on and within the first delay period afterwards.

3. The open circuit fault determination method according to claim 2, wherein The range of the first delay period includes: 10 - 60 s.

4. The open-circuit fault judgment method according to claim 1, wherein, The calculation of the first fundamental effective value includes: performing a Fourier transform on the sum of the first corrected zero-sequence current and the second corrected zero-sequence current; The calculation of the second fundamental effective value includes: performing a Fourier transform on the neutral point zero-sequence current.

5. The open-circuit fault judgment method according to claim 1, wherein, The first threshold includes: The second threshold includes: Wherein, k1 is the first reliability coefficient, k2 is the second reliability coefficient, and I n is the secondary side of the current transformer for detecting the neutral zero-sequence point voltage.

6. The open-circuit fault determination method according to claim 1, wherein, It further includes: Within the second delay period after being judged as an open-circuit fault, it is still determined as an open-circuit fault.

7. The open-circuit fault determination method according to claim 6, wherein The range of the second delay period includes: 20 - 60 ms.

8. An open - circuit fault judgment device for the zero - sequence current loop of the neutral point on the high - voltage side of a transformer, which is used to execute the open - circuit fault judgment method described in any one of claims 1 - 7, characterized in that, The open-circuit fault judgment device includes: A current parameter acquisition module, configured to collect the first high-voltage side current, the second high-voltage side current, and the neutral point zero-sequence current of the transformer when the transformer meets the no-load charging condition; A current conversion module, configured to calculate the corresponding first zero-sequence current and second zero-sequence current according to the first high-voltage side current and the second high-voltage side current respectively; and use the neutral point zero-sequence current as a reference to correct the first zero-sequence current and the second zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current; An effective value extraction module, configured to calculate the first fundamental effective value according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and calculate the second fundamental effective value according to the neutral point zero-sequence current; A fault judgment module, configured to judge as an open-circuit fault when the first fundamental effective value is higher than a preset first threshold and the second fundamental effective value is lower than a preset second threshold.

9. The open-circuit fault judgment device according to claim 8, characterized in that, It further includes: A no-load charging judgment module, configured to judge whether the transformer meets the no-load charging condition.

10. An electronic device, characterized in that, Including: One or more processors; A storage device, configured to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the open-circuit fault judgment method according to any one of claims 1 - 7.

11. A computer-readable medium having a computer program stored thereon, characterized in that, When the described program is executed by a processor, it implements the open-circuit fault judgment method described in any one of claims 1-7.

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