CN115616448A - Open circuit fault judgment method and device for neutral point zero sequence current loop on high-voltage side of transformer, electronic equipment and computer readable medium - Google Patents
Open circuit fault judgment method and device for neutral point zero sequence current loop on high-voltage side of transformer, electronic equipment and computer readable medium Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/54—Testing for continuity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/62—Testing of transformers
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Abstract
Provided are a method and a device for judging the open circuit fault of a neutral point zero sequence current loop on a high-voltage side of a transformer, electronic equipment and a computer readable medium. The method comprises the following steps: when the transformer meets the empty 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; correcting the first zero-sequence current and the second zero-sequence current by taking the neutral zero-sequence current as a reference so as to obtain a first corrected zero-sequence current and a second corrected zero-sequence current; calculating a first fundamental wave effective value according to the sum of the first correction zero sequence current and the second correction zero sequence current, and calculating a second fundamental wave effective value according to the neutral point zero sequence current; and when the first fundamental wave effective value is higher than a preset first threshold value and the second fundamental wave effective value is lower than a preset second threshold value, judging that the circuit breaking fault occurs. The fault can be judged without external test equipment or changing a secondary circuit.
Description
Technical Field
The application relates to the field of relay protection of power systems, in particular to a method and a device for judging open circuit fault of a neutral point zero-sequence current loop on a high-voltage side of a transformer, electronic equipment and a computer readable medium.
Background
In an electric power system, electric energy generated by a generator of a power plant is transmitted to a power grid through a main transformer, and the main generator increases the voltage output by the power plant, so that the rated high-voltage requirement of the power grid is met. Therefore, the safe and stable operation of the main transformer of the power plant is a prerequisite condition for stable power generation and full-load power generation of the generator set, and is the key for reliable operation of the power plant.
The open circuit fault of the neutral point zero sequence current loop on the high-voltage side of the transformer is one of common faults in the operation process of the transformer. When the zero-sequence current loop of the neutral point on the high-voltage side is broken, for example, due to factors such as leakage of a sampling loop after maintenance, insulation breakdown caused by line aging and the like, the transformer has single-phase grounding or serious turn-to-turn short circuit fault. The zero sequence protection of the transformer grounding can be refused, thereby causing that the fault can not be cut off in time and being unfavorable for the protected equipment.
When the transformer normally operates, three-phase currents are balanced, and the current of a neutral point zero-sequence current loop on the high-voltage side of the transformer is very small and basically close to zero, so that whether the detection loop is broken or not cannot be reflected by normal working current. At present, for a transformer in an off-state, a method of performing a single-phase grounding short-circuit test on a high-voltage side of the transformer is generally adopted to verify whether a zero-sequence current loop of a neutral point on the high-voltage side of the transformer is normal. The method needs to change a primary loop and perform a grounding short circuit experiment by means of external test equipment. The testing method has the advantages of complex steps, long time consumption and high cost, and can cause certain damage to the transformer.
Disclosure of Invention
Based on this, in order to solve the problems that a primary circuit needs to be changed and an external test device is used, the steps are complex, the time consumption is long and the cost is high when a test method is adopted to judge the fault of the neutral point zero sequence current loop at the high-voltage side of the transformer, the method and the device for judging the open circuit fault of the neutral point zero sequence current loop at the high-voltage side of the transformer, the electronic device and the computer readable medium are provided.
According to a first aspect of the present application, there is provided a method for determining an open circuit fault of a zero sequence current loop of a neutral point on a high voltage side of a transformer, including:
the method for judging the open circuit fault of the neutral point zero sequence current loop at the high-voltage side of the transformer comprises the following steps:
when the transformer meets the empty charging condition, collecting a first high-voltage side current, a second high-voltage side current and a neutral 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;
correcting the first zero-sequence current and the second zero-sequence current by taking the neutral zero-sequence current as a reference 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 zero sequence current;
and when the first fundamental wave effective value is higher than a preset first threshold value and the second fundamental wave effective value is lower than a preset second threshold value, judging that the circuit breaking fault occurs.
According to some embodiments of the application, the empty-charge condition comprises:
the high-voltage side switch of the transformer is within a first time delay from the moment of breaking to closing and later.
According to some embodiments of the application, the range of the first delay includes: 10-60s.
According to some embodiments of the application, the calculating the corresponding first and second zero sequence currents comprises:
the calculation is performed according to the following formula:
wherein i a_h1 (k)、i b_h1 (k) And i c_h1 (k) Three-phase sampling values of the first high-voltage side current are respectively obtained; i.e. i 3I0_Cal_h1 (k) Sampling value of the first zero sequence current; i.e. i a_h2 (k)、i b_h2 (k) And i c_h2 (k) Three-phase sampling values of second high-voltage side current are respectively obtained; i.e. i 3I0_Cal_h2 (k) Sampling value of a second zero sequence current of the transformer; k is the sampling sequence.
According to some embodiments of the application, the correcting the first zero sequence current and the second zero sequence current with reference to the neutral zero sequence current to obtain a first corrected zero sequence current and a second corrected zero sequence current comprises:
calculating the first corrected zero-sequence current and the second corrected zero-sequence current according to the following formulas,
wherein i 3 ′ I0_Cal_h1 (k) And i 3 ′ I0_Cal_h2 (k) Respectively a first corrected zero sequence current and a second corrected zero sequence current; n is a radical of CT11 、N CT21 And N CT31 The primary sides of the current transformers are used for collecting the first high-voltage side current, the second high-voltage side current and the high-voltage side neutral point zero sequence current respectively.
According to some embodiments of the application, the calculating the first fundamental effective value comprises: performing a Fourier transform on a sum of the first corrected zero-sequence current and the second corrected zero-sequence current; the calculating the second fundamental effective value comprises: and carrying out Fourier transformation on the neutral point zero sequence current.
According to some embodiments of the application, the first threshold is calculated according to the following formula:
the second threshold is calculated according to the following formula:
wherein k is 1 Is the first reliability coefficient, k 2 Is the second reliability factor, I n The secondary side of the current transformer is used for detecting the neutral zero sequence point voltage.
According to some embodiments of the present application, the open circuit fault determining method further includes:
and determining to be the open-circuit fault within the second time delay after the judgment of the open-circuit fault.
According to some embodiments of the application, the range of the second delay includes: 20-60ms.
According to another aspect of the application, an open circuit fault judgment device for a neutral point zero sequence current loop on a high-voltage side of a transformer is provided. The disconnection fault determination device may include:
the current parameter acquisition module is used for acquiring a first high-voltage side current, a second high-voltage side current and a neutral point zero sequence current of the transformer when the transformer meets an empty charging condition;
the current conversion module is used for 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; correcting the first zero-sequence current and the second zero-sequence current by taking the neutral zero-sequence current as a reference to obtain a first corrected zero-sequence current and a second corrected zero-sequence current;
the effective value extraction module is used for 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 zero sequence current;
and the fault judgment module is used for judging that the circuit breaking fault occurs when the first fundamental wave effective value is higher than a preset first threshold value and the second fundamental wave effective value is lower than a preset second threshold value.
According to some embodiments of the present application, the open circuit fault determining apparatus may further include:
and the empty charging judgment module is used for judging whether the transformer meets the empty charging condition.
According to another aspect of the present application, there is provided an electronic device for open fault determination of a transformer high-voltage side neutral point zero sequence current loop, including:
one or more processors;
storage means for storing one or more programs;
when the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the open circuit fault determination method.
According to another aspect of the present application, there is also provided a computer-readable medium, on which a computer program is stored, which when executed by a processor, implements the above open circuit fault determination method.
According to the open circuit fault judgment method of the neutral point zero sequence current loop on the high-voltage side of the transformer, the open circuit fault of the neutral point zero sequence current loop on the high-voltage side is judged through the collection and conversion of the electrical parameters, and external test equipment does not need to be added and a secondary loop does not need to be modified.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without exceeding the protection scope of the present application.
FIG. 1 shows a schematic of current measurement on each side of a power plant transformer according to an example embodiment of the present application;
FIG. 2 illustrates a flow chart of a method for open circuit fault determination according to an exemplary embodiment of the present application;
FIG. 3 illustrates a logic diagram of a method for open circuit fault determination according to an exemplary embodiment of the present application;
fig. 4 is a block diagram showing a disconnection fault determination apparatus according to an exemplary embodiment of the present application;
fig. 5 is a block diagram illustrating a disconnection fault determination apparatus according to another exemplary embodiment of the present application;
fig. 6 shows a block diagram of an electronic device for open circuit fault determination according to an example embodiment of the present application.
Detailed Description
Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals denote the same or similar parts in the drawings, and thus, a repetitive description thereof will be omitted.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments of the application. One skilled in the relevant art will recognize, however, that the subject matter of the present application can be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known methods, devices, implementations, or operations have not been shown or described in detail to avoid obscuring aspects of the application.
It will be understood that, although the terms first, second, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one element from another. Thus, a first component discussed below may be termed a second component without departing from the teachings of the present concepts. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Those skilled in the art will appreciate that the drawings are merely schematic representations of exemplary embodiments, which may not be to scale. The blocks or flows in the drawings are not necessarily required to practice the present application and therefore should not be used to limit the scope of the present application.
Fig. 1 shows a schematic diagram of the measurement of the high side currents of a power plant transformer according to an exemplary embodiment of the present application.
As shown in fig. 1, the electric power generated by the generator 100 of the power plant is transmitted to the grid through a transformer 200. The current of each high-voltage side of the transformer is detected by a three-phase current transformer. For example, the high-voltage side 210 of the transformer detects three currents thereof through a three-phase current transformer 211 (CT 1), the high-voltage side 220 of the transformer detects three currents thereof through a three-phase current transformer 221 (CT 2), and the high-voltage side 230 of the transformer detects a neutral zero-sequence current through a single-phase current transformer 231 (CT 3). As shown in fig. 1, F represents the position of the neutral point zero-sequence current loop on the high-voltage side of the transformer; 300 denotes a current association node for judging the open circuit fault of the neutral point zero sequence current loop on the high-voltage side of the transformer, the current collected by the current transformer 211, the current collected by the current transformer 221 and the neutral point zero sequence current collected by the current transformer 231 are collected to the current association node 300, and the open circuit fault of the neutral point zero sequence current loop can be judged by calculation and comparison.
The basic parameters of the transformer shown in fig. 1 include: rated capacity S n Is 1200MVA; the connection mode is YND11, high-voltage side rated voltage U hn Is 500kV, rated voltage U of low-voltage side ln Is 24kV; the parameters of the three-phase current transformer include: the ratio of the primary side to the secondary side of the current transformer 211 (CT 1) is 2000A/1A; the ratio of the primary side to the secondary side of the current transformer 221 (CT 2) is 2000A/1A; the ratio of the primary side to the secondary side of the current transformer 231 (CT 3) is 800A/1A. The parameters of the transformer and the current transformer are not limited by the application.
Because the three-phase current is almost completely symmetrical when the transformer normally operates and the zero-sequence current of the neutral point at the high-voltage side is extremely small, the existing protection method is difficult to distinguish when the open circuit fault occurs at the position F. In addition, a method of changing a primary loop and using external test equipment needs a primary grounding short circuit experiment, and has the disadvantages of complex steps, long time consumption, high cost and certain damage to the transformer.
In order to solve the above problems, the present application intends to provide a method for determining an open circuit fault of a neutral point zero sequence current loop on a high voltage side of a transformer, which determines the open circuit fault of the neutral point zero sequence current loop on the high voltage side through the collection and conversion of electrical parameters without adding external test equipment and modifying a secondary loop.
Fig. 2 shows a flowchart of a method for open circuit fault determination according to an example embodiment of the present application.
As shown in fig. 2, according to an exemplary embodiment of the present application, the method for determining an open circuit fault of a neutral point zero sequence current loop on a high-voltage side of a transformer provided by the present application includes the following steps.
In step S210, when the transformer meets the empty charge condition, a first high-voltage side current, a second high-voltage side current and a neutral zero sequence current of the transformer are collected.
When the transformer normally operates, three-phase currents are almost completely symmetrical, the zero-sequence current of a neutral point on a high-voltage side is extremely small, and unbalanced current can be generated only when the transformer is in an empty charging state, namely, a switch on the high-voltage side of the transformer is switched from a breaking state to a switching-on state in the first time delay. Therefore, in the open-circuit fault determination method provided by the application, whether the transformer meets the empty charge condition is determined first.
Taking a 3/2 circuit breaker wiring mode as an example, a circuit breaker switch and a side switch in the high-voltage side of the transformer are in a separated position, and when any switch is in a closed position from a separated position, the transformer is judged to meet the empty charge condition. And then after the first time delay t, the empty charge condition of the transformer is not satisfied any more. According to some embodiments of the present application, the first delay t may range between 10-60s.
When the transformer meets the empty charging condition, the first high-voltage side current, the second high-voltage side current and the neutral zero sequence current of the transformer can be respectively collected through the current transformer. For example, a three-phase current of the high voltage side 210 of the transformer, i.e., a first high voltage side current, is detected by the current transformer 211 (CT 1) in fig. 1; detecting a three-phase current on the high-voltage side 220 of the transformer, namely a second high-voltage side current, by a current transformer 221 (CT 2) in fig. 1; the current of the high-voltage side 230 of the transformer, i.e. the high-voltage side neutral zero sequence current, is detected by the current transformer 231 (CT 3) in fig. 1.
In step S220, a corresponding first zero-sequence current and a corresponding second zero-sequence current are calculated according to the first high-voltage-side current and the second high-voltage-side current, respectively.
According to an exemplary embodiment of the application, after a first high-voltage side current sampling value on the high-voltage side of the transformer and a second high-voltage side current sampling value on the high-voltage side of the transformer are acquired by the current transformer, corresponding first zero-sequence current and second zero-sequence current can be calculated according to the following formulas, namely self-generated zero-sequence current on the high-voltage side and self-generated zero-sequence current on the high-voltage side.
Wherein i a_h1 (k)、i b_h1 (k) And i c_h1 (k) Three-phase sampling values of first high-voltage side current on the high-voltage side of the transformer are respectively obtained; i.e. i 3I0_Cal_h1 (k) Sampling value of the first zero sequence current at the high-voltage side; i.e. i a_h2 (k)、i b_h2 (k) And i c_h2 (k) Three-phase sampling values of second high-voltage side currents on two high-voltage sides respectively; i.e. i 3I0_Cal_h2 (k) Sampling values of second zero sequence currents at two sides of the high voltage; k is the sampling sequence.
In step S230, the first zero-sequence current and the second zero-sequence current are corrected by using the neutral zero-sequence current as a reference to obtain a first corrected zero-sequence current and a second corrected zero-sequence current.
Because the current transformer parameters of the transformer for collecting three-phase current at each high-voltage side are different, namely the primary sides are different, before fault judgment is carried out through the current parameters, zero sequence current at each side needs to be corrected. After correction, the zero sequence current of each side is converted to the same reference, so that the correctness of subsequent judgment is ensured.
According to an exemplary embodiment of the present application, the neutral zero sequence current is used as a reference for performing the correction, that is, the primary side of the current transformer 231 (CT 3) in fig. 1, which collects the neutral zero sequence current of the high-voltage side 230, is used as a reference for performing the balance coefficient adjustment on the self-generated zero sequence current of the high-voltage side of the transformer, the self-generated zero sequence current of the high-voltage side of the transformer and the neutral zero sequence current of the high-voltage side of the transformer, and the first corrected zero sequence current and the second corrected zero sequence current are calculated according to the following formulas.
Wherein i 3 ′ I0_Cal_h1 (k) And i 3 ′ I0_Cal_h2 (k) Respectively a first correction zero sequence current (a sampling value of the self-production correction zero sequence current on the high-voltage side of the transformer) and a second correction zero sequence current (a sampling value of the self-production correction zero sequence current on the high-voltage side of the transformer); i.e. i I0_NP (k) And i I ′ 0_NP (k) Respectively sampling value of neutral point zero sequence current at high voltage side of transformer and transformer heightCorrecting a zero-sequence current sampling value by a neutral point on a pressure side; n is a radical of CT11 、N CT21 And N CT31 The primary sides of the high-voltage side current transformer, the high-voltage side current transformer and the high-voltage side neutral point zero sequence current transformer of the transformer are respectively. Since the primary side of the current transformer 231 (CT 3) of the neutral zero-sequence current on the high-voltage side 230 is used as the reference for correction in the present application, the sampling value i of the neutral zero-sequence current on the high-voltage side of the transformer is obtained I0_NP (k) And zero-sequence current sampling value i for correcting neutral point on high-voltage side of transformer I ′ 0_NP (k) Are equal.
N CT11 、N CT21 And N CT31 Are intrinsic parameters of the current transformer. Taking the converter transformer in fig. 1 as an example, the primary side N of the current transformer 211 (CT 1) CT11 Primary side N of current transformer 221 (CT 2) of 2000A CT21 Is 2000A; primary side N of current transformer 231 (CT 3) CT31 Is 800A.
In step S240, a first fundamental effective value is calculated according to the sum of the first corrected zero-sequence current and the second corrected zero-sequence current, and a second fundamental effective value is calculated according to the neutral zero-sequence current.
And correcting the first zero-sequence current and the second zero-sequence current by taking the neutral zero-sequence current as a reference, obtaining a first corrected zero-sequence current and a second corrected zero-sequence current, and then obtaining a first fundamental wave effective value and a second fundamental wave effective value through Fourier transform. For example, a first fundamental effective value is obtained after fourier transform is performed on the sum of the first corrected zero-sequence current and the second corrected zero-sequence current; and after the neutral point zero sequence current is subjected to Fourier transform, a second fundamental wave effective value is obtained.
In step S250, when the first fundamental wave effective value is higher than a preset first threshold value and the second fundamental wave effective value is lower than a preset second threshold value, it is determined that a circuit breaking fault occurs.
Taking the wiring mode of the transformer as a 3/2 breaker as an example, the judgment condition that the self-produced zero-sequence correction current at the high-voltage side of the transformer is high is as follows: the effective value of the fundamental wave (first effective value) of the self-produced zero-sequence correction current on the high-voltage side of the transformer is higher than a first threshold value I 0_set1 Namely:
wherein, I 3 ′ I0_Cal Is the first fundamental effective value, I 0_set1 Is a first threshold.
According to some embodiments of the application, the first threshold I 0_set1 Can pass through the first reliability coefficient k 1 And the secondary side of the reference side current transformer (namely the secondary side of the current transformer for detecting the neutral zero-sequence point voltage on the high-voltage side). In general, the first reliability factor k 1 Can be taken as 5 percent. Taking the current transformer in FIG. 1 as an example, the secondary side I n Take 1A.
Similarly, the low zero-sequence correction current determination condition of the neutral point on the high-voltage side of the transformer is as follows: the effective value (second effective value) of the fundamental wave of the zero-sequence correction current of the neutral point on the high-voltage side of the transformer is lower than a second threshold value I 0_set2 Namely:
wherein, I I ′ 0_NP Is a second fundamental effective value; i is 0_set2 Is a second threshold.
According to some embodiments of the application, the second threshold I 0_set2 May pass through a second reliability coefficient k 2 And the secondary side of the reference side current transformer (namely the secondary side of the current transformer for detecting the neutral zero-sequence point voltage on the high-voltage side). In general, the second reliability factor k 2 Can be taken as 2.5 percent. Taking the current transformer in FIG. 1 as an example, the secondary side I n Take 1A.
When the first fundamental wave effective value is higher than a preset first threshold value and the second fundamental wave effective value is lower than a preset second threshold value, namely the following conditions are met, the neutral point zero sequence circuit breaking fault is judged:
in addition, according to other embodiments of the present application, relay protection of a power system generally requires time delay protection. Therefore, in the present application, the open-circuit fault is determined within the second delay time T after the determination as the open-circuit fault. Typically, the second delay T may range from 20 to 60ms. The second delay T in the exemplary embodiment of the present application takes 40ms.
Fig. 3 illustrates a logic diagram of a method for open fault determination according to an exemplary embodiment of the present application.
As shown in fig. 3, the fault determination logic process of the open-circuit fault determination method provided by the present application includes:
criterion 1: the fundamental wave effective value of the zero sequence correction current self-produced on the high-voltage side of the transformer, namely the first fundamental wave effective value, is higher than a preset first threshold value (S310);
criterion 2: the fundamental wave effective value of the zero sequence correction current of the neutral point on the high-voltage side of the transformer, namely the second fundamental wave effective value, is higher than a preset second threshold value (S320);
criterion 3: the transformer meets the empty charging condition, namely the high-voltage side switch of the transformer is divided into the moment of closing (S330) and the first delay t (S340) later;
and logic judgment of AND gate is carried out in S340, namely whether the three criteria are all satisfied is judged. When the logical judgment of the AND gate is passed, time delay protection is carried out in S350, and finally fault judgment action is carried out in S370, namely the fault judgment of the high-voltage side neutral point zero sequence current loop is carried out.
Fig. 4 is a block diagram illustrating a disconnection fault determination apparatus according to an exemplary embodiment of the present application.
According to another aspect of the present application, there is also provided a device 400 for determining a breaking fault of a neutral point zero-sequence current loop on a high-voltage side of a transformer. As shown in fig. 4, according to an exemplary embodiment of the present application, the open circuit fault determining apparatus 400 includes a current parameter collecting module 420, a current converting module 430, a valid value extracting module 440, and a fault determining module 450.
The current parameter collecting module 420 may be configured to collect a first high-voltage side current, a second high-voltage side current, and a neutral zero sequence current of the transformer when the transformer satisfies an empty charge condition. For example, a first high-voltage side current of the high-voltage side 210 of the transformer is collected by the current transformer 211 (CT 1) in fig. 1; collecting a second high-voltage side current of the high-voltage side 220 of the transformer by a current transformer 221 (CT 2) in fig. 1; the high-voltage side neutral zero sequence current of the high-voltage side 230 of the transformer is collected by the current transformer 231 (CT 3) in fig. 1.
The current conversion module 430 may be configured to calculate a first zero-sequence current and a second zero-sequence current according to the first high-voltage-side current and the second high-voltage-side current, respectively; and correcting the first zero-sequence current and the second zero-sequence current by taking the neutral zero-sequence current as a reference so as to obtain a first corrected zero-sequence current and a second corrected zero-sequence current.
Because the current transformer parameters of the current collected by each high-voltage side of the transformer are different, that is, the primary sides are different, before fault judgment is performed through the current parameters, zero sequence current of each side needs to be corrected. After the correction is carried out, the zero sequence current of each side is converted to the same reference, so that the accuracy of subsequent judgment is ensured. In an example implementation of the present application, the correction is performed with reference to a neutral zero sequence current.
The effective value extracting module 440 may be configured to calculate a first fundamental effective value according to a 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 zero-sequence current. By means of fourier transformation, the corresponding fundamental effective value can be obtained.
The fault determining module 450 may be configured to determine that the fault is an open circuit fault when the first effective value of the fundamental wave is higher than a preset first threshold and the second effective value of the fundamental wave is lower than a preset second threshold.
Fig. 5 is a block diagram illustrating a disconnection fault determination apparatus according to another exemplary embodiment of the present application.
According to another embodiment of the present application, the open circuit fault determination device 400 may further include an empty charge determination module 410. The empty charge determining module 410 may be configured to determine whether the transformer satisfies an empty charge condition. Taking a 3/2 circuit breaker wiring mode as an example, a circuit breaker switch and a side switch in the high-voltage side of the transformer are in a separated position, and when any switch is in a closed position from a separated position, the transformer is judged to meet the empty charge condition. And then after the first time delay t, the empty charge condition of the transformer is not satisfied any more. According to some embodiments of the present application, the first delay t may range between 10-60s.
Fig. 6 shows a block diagram of an electronic device for open circuit fault determination according to an example embodiment of the present application.
The application also provides electronic equipment for judging the open circuit fault of the neutral point zero sequence current loop on the high-voltage side of the transformer. The control device 500 shown in fig. 6 is only an example, and should not bring any limitation to the function and the range of use of the embodiment of the present application.
As shown in fig. 6, the control device 500 is 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 memory unit 520, a bus 530 that couples various system components including the memory unit 520 and the processing unit 510, and the like.
The storage unit 520 stores program code, which can be executed by the processing unit 510, so that the processing unit 510 executes the methods according to the above embodiments of the present application described in the present specification.
The memory unit 520 may include readable media in the form of volatile memory units, such as a random access memory unit (RAM) 5201 and/or a cache memory unit 5202, and may further include a read-only memory unit (ROM) 5203.
The electronic device 500 may also communicate with one or more external devices 5001 (e.g., touch screen, keyboard, pointing device, bluetooth device, etc.), with one or more devices that enable a user to interact with the electronic device 500, and/or with any devices (e.g., router, modem, etc.) that enable the electronic device 500 to communicate with one or more other computing devices. Such communication may occur via input/output (I/O) interfaces 550. Also, the electronic device 500 may communicate with one or more networks (e.g., a Local Area Network (LAN), a Wide Area Network (WAN), and/or a public network, such as the internet) via the network adapter 560. The network adapter 560 may communicate with other modules of the electronic device 500 via the bus 530. It should be appreciated that although not shown in the figures, other hardware and/or software modules may be used in conjunction 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, among others.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the description of the embodiments is only intended to facilitate the understanding of the methods and their core concepts of the present application. Meanwhile, a person skilled in the art should, according to the idea of the present application, change or modify the embodiments and applications of the present application based on the scope of the present application. In view of the above, the description should not be taken as limiting the application.
Claims (13)
1. A method for judging open circuit fault of a neutral point zero sequence current loop on a high-voltage side of a transformer is characterized by comprising the following steps:
when the transformer meets the empty charging condition, collecting a first high-voltage side current, a second high-voltage side current and a neutral 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;
correcting the first zero-sequence current and the second zero-sequence current by taking the neutral zero-sequence current as a reference 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 zero sequence current;
and when the first fundamental wave effective value is higher than a preset first threshold value and the second fundamental wave effective value is lower than a preset second threshold value, judging that the circuit breaking fault occurs.
2. The open circuit fault determination method according to claim 1, wherein the empty charge condition includes:
the high-voltage side switch of the transformer is within a first time delay from the moment of breaking to closing and later.
3. The open circuit fault determination method according to claim 2, wherein the range of the first delay time includes: 10-60s.
4. The method of claim 1, wherein the calculating the corresponding first and second zero sequence currents comprises:
the calculation is performed according to the following formula:
wherein i a_h1 (k)、i b_h1 (k) And i c_h1 (k) Three-phase sampling values of the first high-voltage side current are respectively obtained; i.e. i 3I0_Cal_h1 (k) Sampling value of the first zero sequence current; i.e. i a_h2 (k)、i b_h2 (k) And i c_h2 (k) Three-phase sampling values of second high-voltage side current are respectively obtained; i.e. i 3I0_Cal_h2 (k) Sampling value of a second zero sequence current of the transformer; k is the sample sequence.
5. The method for determining a disconnection fault of claim 4, wherein the step of correcting the first zero-sequence current and the second zero-sequence current based on the neutral zero-sequence current to obtain a first corrected zero-sequence current and a second corrected zero-sequence current comprises:
calculating the first corrected zero-sequence current and the second corrected zero-sequence current according to the following formulas,
wherein, i' 3I0_Cal_h1 (k) And i' 3I0_Cal_h2 (k) Respectively a first corrected zero sequence current and a second corrected zero sequence current; n is a radical of CT11 、N CT21 And N CT31 The primary sides of the current transformers are used for collecting the first high-voltage side current, the second high-voltage side current and the high-voltage side neutral point zero sequence current respectively.
6. The open circuit fault determination method according to claim 5,
the calculating the first fundamental effective value comprises: performing a Fourier transform on a sum of the first corrected zero-sequence current and the second corrected zero-sequence current;
the calculating the second fundamental effective value comprises: and carrying out Fourier transformation on the neutral point zero sequence current.
7. The open circuit fault determination method according to claim 1,
the first threshold includes:
the second threshold includes:
wherein k is 1 Is the first reliability coefficient, k 2 Is the second reliability factor, I n The secondary side of the current transformer is used for detecting the neutral zero sequence point voltage.
8. The open circuit fault determination method according to claim 1, further comprising:
and determining to be the open-circuit fault within the second time delay after the judgment of the open-circuit fault.
9. The method of claim 8, wherein the second delay time range comprises: 20-60ms.
10. The utility model provides a transformer high pressure side neutral point zero sequence current return circuit's fault judgement device that opens circuit which characterized in that includes:
the current parameter acquisition module is used for acquiring a first high-voltage side current, a second high-voltage side current and a neutral point zero sequence current of the transformer when the transformer meets an empty charging condition;
the current conversion module is used for 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; correcting the first zero-sequence current and the second zero-sequence current by taking the neutral zero-sequence current as a reference to obtain a first corrected zero-sequence current and a second corrected zero-sequence current;
the effective value extraction module is used for calculating a first fundamental wave 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 wave effective value according to the neutral point zero sequence current;
and the fault judgment module is used for judging that the circuit breaking fault occurs when the first fundamental wave effective value is higher than a preset first threshold value and the second fundamental wave effective value is lower than a preset second threshold value.
11. The disconnection fault determination device of claim 10, further comprising:
and the empty charging judgment module is used for judging whether the transformer meets the empty charging condition.
12. An electronic device, comprising:
one or more processors;
storage means for storing one or more programs;
when executed by the one or more processors, cause the one or more processors to implement the open circuit fault determination method of any of claims 1-9.
13. A computer-readable medium, on which a computer program is stored, which, when being executed by a processor, carries out the method for determining a disconnection fault according to any one of claims 1 to 9.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110807313.8A CN115616448A (en) | 2021-07-16 | 2021-07-16 | Open circuit fault judgment method and device for neutral point zero sequence current loop on high-voltage side of transformer, electronic equipment and computer readable medium |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110807313.8A CN115616448A (en) | 2021-07-16 | 2021-07-16 | Open circuit fault judgment method and device for neutral point zero sequence current loop on high-voltage side of transformer, electronic equipment and computer readable medium |
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