CN108767814B - Electromagnetic voltage transformer fault analysis method and device - Google Patents
Electromagnetic voltage transformer fault analysis method and device Download PDFInfo
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- CN108767814B CN108767814B CN201810681931.0A CN201810681931A CN108767814B CN 108767814 B CN108767814 B CN 108767814B CN 201810681931 A CN201810681931 A CN 201810681931A CN 108767814 B CN108767814 B CN 108767814B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
- H02H7/045—Differential protection of transformers
- H02H7/0455—Differential protection of transformers taking into account saturation of current transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
- H02H7/262—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of switching or blocking orders
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
- H02H7/263—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations involving transmissions of measured values
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- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The embodiment of the invention provides a fault analysis method and a fault analysis device for an electromagnetic voltage transformer, wherein the method comprises the following steps: acquiring a transient process signal for saturating the mutual inductor, and acquiring a neutral point grounding current of a primary winding of the mutual inductor and a three-phase voltage of a secondary winding of the mutual inductor; calculating the three-phase voltage to obtain the zero-sequence voltage characteristic quantity of the mutual inductor; and correspondingly determining the fault reason of the mutual inductor according to the judgment result after judging that the zero sequence voltage characteristic quantity and/or the neutral point grounding current meet the alarm condition. According to the invention, the neutral point current and the three-phase voltage of the mutual inductor are monitored, the zero-sequence voltage characteristic quantity and the neutral point current are used as variables to judge whether the mutual inductor fails or not, and finally, the fault reason of the mutual inductor is determined according to the judgment result, so that the voltage and the current in the transient process of the mutual inductor can be monitored when the mutual inductor fails, and the fault reason of the mutual inductor is accurately analyzed on the basis of the voltage and the current obtained through monitoring.
Description
Technical Field
The invention relates to the field of voltage transformers, in particular to a fault analysis method and a fault analysis device for an electromagnetic voltage transformer.
Background
As a voltage conversion device, an electromagnetic voltage transformer (PT) is a necessary front-end device for protecting, metering and measuring a power system, which can convert a high voltage, which is dangerous in a current system, into a low voltage, which can be detected by a measuring device. However, the electromagnetic transformer has a nonlinear characteristic, and iron core saturation may be caused under the excitation of transient processes such as closing of an empty bus, fault recovery and the like, so that inductance value is reduced, current is increased, and a winding of the transformer is burnt or an explosion fault is caused. Therefore, qualitative and quantitative analysis is needed to be carried out on the fault reason of the mutual inductor, and the limitation that the fault reason is difficult to confirm by the existing evaluation method is changed.
Whether the mutual inductor generates saturation and resonance phenomena in the transient process of a power grid or not is related to the structural parameters of the power grid where the mutual inductor is located, the faults are prone to the occurrence that the faults cannot be accurately predicted due to the fact that the wiring types of the system and the switching process are different, the finding and analysis of the fault reasons after the faults lack basis, the faults of the equipment cannot be distinguished, and the faults are caused due to poor parameter matching. At present, two methods can be adopted for the fault of the mutual inductor, one method is that a simulation method is adopted, system parameters are calculated after the fault occurs, and whether the possibility of the fault caused by resonance exists is presumed according to the parameter characteristics and the overvoltage amplitude value of the system parameters and compared with empirical data, but the method only remains guessing and is not fault-qualitative; the second method adopts field actual measurement, and obtains the transient characteristics in actual switching by installing a universal voltage divider on the field and switching equipment or lines. However, on-site actual measurement is usually performed only for voltage, but experience proves that most PT faults are one-time overcurrent burning, and due to the nonlinearity of the transformer, the actual current value cannot be presumed through the voltage of the transformer. In addition, the method can not predict the system ground fault, and is difficult to artificially set a fault point on the site so as to monitor the fault and the fault recovery process. In addition, the existing general overvoltage monitoring device is mainly portable and needs to be dismantled after the switching test is completed, and the characteristic quantity of the transformer in the saturation process has dispersity, so that the characteristic of the transformer can not be fully reflected by limited measurement. Therefore, the two methods cannot directly reflect PT fault reasons, so that mutual inductors installed at partial positions of a power grid are failed again and again, and hidden dangers are brought to safety lock production.
Therefore, it is an urgent technical problem to be solved by those skilled in the art to provide a method and an apparatus for analyzing a fault of a voltage transformer in a timely and accurate manner.
Disclosure of Invention
The embodiment of the invention provides a fault analysis method and device for an electromagnetic voltage transformer, which can monitor the state of the transformer and realize the search and analysis of the fault reason of the transformer.
According to one aspect of the invention, a fault analysis method for an electromagnetic voltage transformer is provided, which comprises the following steps:
acquiring a transient process signal for saturating the mutual inductor, and then acquiring a neutral point grounding current of a primary winding of the mutual inductor and a three-phase voltage of a secondary winding of the mutual inductor;
calculating the three-phase voltage to obtain a zero-sequence voltage characteristic quantity of the mutual inductor;
and correspondingly determining the fault reason of the mutual inductor according to the judgment result after judging that the zero sequence voltage characteristic quantity and/or the neutral point grounding current meet the alarm condition.
Preferably, the transient process signal for saturating the transformer is a closing signal of a circuit breaker or a recovery signal of the single-phase ground fault of the power grid.
Preferably, the calculating the three-phase voltage to obtain the zero-sequence voltage characteristic quantity of the transformer specifically includes:
and synthesizing the three-phase voltage to obtain an open delta voltage, and extracting the zero sequence voltage characteristic quantity of the open delta voltage.
Preferably, the zero sequence voltage characteristic quantity includes: voltage peak value, zero sequence half harmonic component amplitude and zero sequence third harmonic component amplitude.
Preferably, the specific step of judging that the zero sequence voltage characteristic quantity and/or the neutral point grounding current satisfy the alarm condition is:
judging that any one of the zero-sequence voltage characteristic quantities is larger than a corresponding preset voltage threshold value in the voltage peak value, the zero-sequence half harmonic component amplitude value and the zero-sequence third harmonic component amplitude value, and then meeting a voltage abnormity warning condition;
and/or
And judging that the neutral point grounding current is larger than a preset current threshold value, and if the neutral point grounding current lasts for a preset time period and is not attenuated, the overcurrent alarm condition is met.
Preferably, the correspondingly determining the fault reason of the transformer according to the judgment result specifically includes:
if the zero sequence third harmonic component amplitude is larger than a corresponding preset voltage threshold value, the neutral point grounding current is larger than a preset current threshold value, and a preset time period is continued without attenuation, determining that the fault of the transformer is caused by overcurrent caused by high-frequency resonance;
if the zero sequence half harmonic component amplitude is larger than the corresponding preset voltage threshold value, the neutral point grounding current is larger than the preset current threshold value, and the preset time period is continued without attenuation, determining that the fault of the transformer is caused by overcurrent caused by frequency division resonance;
if the voltage peak value is larger than the corresponding preset voltage threshold value, and the neutral point grounding current is larger than the preset current threshold value, and lasts for a preset time period without attenuation, determining that the fault of the transformer is caused by overcurrent caused by power frequency resonance;
if the overcurrent alarm condition is met and the voltage abnormity alarm condition is not met, determining that the fault of the transformer is caused by a short circuit or a load;
and if the voltage abnormity warning condition is met and the overcurrent warning condition is not met, determining that the fault of the transformer is caused by insulation defect.
According to another aspect of the present invention, there is provided an electromagnetic voltage transformer fault analysis apparatus including:
the acquisition module is used for acquiring neutral point grounding current of a primary winding of the mutual inductor and three-phase voltage of a secondary winding of the mutual inductor after acquiring a transient process signal for saturating the mutual inductor;
the calculation module is used for calculating the three-phase voltage to obtain the zero-sequence voltage characteristic quantity of the mutual inductor;
and the determining module is used for correspondingly determining the fault reason of the mutual inductor according to the judging result after judging that the zero sequence voltage characteristic quantity and/or the neutral point grounding current meet the alarm condition.
Preferably, the transient process signal for saturating the transformer is a closing signal of a circuit breaker or a recovery signal of the single-phase ground fault of the power grid.
According to another aspect of the present invention, there is provided an electromagnetic voltage transformer fault analysis apparatus including: a memory, and a processor coupled to the memory;
the processor is configured to execute the electromagnetic voltage transformer fault analysis method described above based on instructions stored in the memory device.
According to another aspect of the present invention, there is provided a computer readable medium having stored thereon a computer program which, when executed by a processor, implements the electromagnetic voltage transformer fault analysis method described above.
According to the technical scheme, the embodiment of the invention has the following advantages:
the embodiment of the invention provides a fault analysis method and a fault analysis device for an electromagnetic voltage transformer, wherein the method comprises the following steps: acquiring a transient process signal for saturating the mutual inductor, and acquiring a neutral point grounding current of a primary winding of the mutual inductor and a three-phase voltage of a secondary winding of the mutual inductor; calculating the three-phase voltage to obtain the zero-sequence voltage characteristic quantity of the mutual inductor; and correspondingly determining the fault reason of the mutual inductor according to the judgment result after judging that the zero sequence voltage characteristic quantity and/or the neutral point grounding current meet the alarm condition. According to the invention, the neutral point current and the three-phase voltage of the mutual inductor are monitored, the zero-sequence voltage characteristic quantity and the neutral point current are used as variables to judge whether the mutual inductor fails or not, and finally, the fault reason of the mutual inductor is determined according to the judgment result, so that the voltage and the current in the transient process of the mutual inductor can be monitored when the mutual inductor fails, and the fault reason of the mutual inductor is accurately analyzed on the basis of the voltage and the current obtained through monitoring.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a schematic flowchart of an embodiment of a fault analysis method for an electromagnetic voltage transformer according to the present invention;
fig. 2 is a schematic structural diagram of an embodiment of an electromagnetic voltage transformer fault analysis device provided by the present invention.
Detailed Description
The embodiment of the invention provides a fault analysis method and device for an electromagnetic voltage transformer, which can monitor the state of the transformer and realize the search and analysis of the fault reason of the transformer.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of a method for analyzing a fault of an electromagnetic voltage transformer according to the present invention includes:
101. acquiring a transient process signal for saturating the mutual inductor, and acquiring a neutral point grounding current of a primary winding of the mutual inductor and a three-phase voltage of a secondary winding of the mutual inductor;
in this embodiment, parameters of a transformer in a power grid are monitored in real time, and after a transient process signal for saturating the transformer is obtained, the acquisition speed of a neutral point grounding current of a primary winding of the transformer and a three-phase voltage of a secondary winding of the transformer is increased, so that parameters in a saturated state of the transformer are obtained.
102. Calculating the three-phase voltage to obtain the zero-sequence voltage characteristic quantity of the mutual inductor;
and after neutral point grounding current and three-phase voltage of the mutual inductor in a saturated state are obtained, calculating the three-phase voltage to obtain corresponding zero-sequence voltage characteristic quantity, and taking the central point grounding current and the zero-sequence voltage characteristic quantity as conditions for judging whether the alarm condition is met or not.
103. And correspondingly determining the fault reason of the mutual inductor according to the judgment result after judging that the zero sequence voltage characteristic quantity and/or the neutral point grounding current meet the alarm condition.
Because the zero sequence voltage characteristic quantity and the neutral point grounding current are separately judged, the results of whether the two quantities meet the alarm condition can be in various combined conditions, and the fault reason of the mutual inductor is correspondingly determined according to the judgment result.
According to the invention, the neutral point current and the three-phase voltage of the mutual inductor are monitored, the zero-sequence voltage characteristic quantity and the neutral point current are used as variables to judge whether the mutual inductor fails or not, and finally, the fault reason of the mutual inductor is determined according to the judgment result, so that the voltage and the current in the transient process of the mutual inductor can be monitored when the mutual inductor fails, and the fault reason of the mutual inductor is accurately analyzed on the basis of the voltage and the current obtained through monitoring.
In order to describe the above embodiment of the method for analyzing the fault of the electromagnetic voltage transformer more specifically, the following provides another embodiment of the method for analyzing the fault of the electromagnetic voltage transformer, and the another embodiment of the method for analyzing the fault of the electromagnetic voltage transformer provided by the present invention includes:
201. acquiring neutral point grounding current of a primary winding of a mutual inductor and three-phase voltage of a secondary winding of the mutual inductor after acquiring a closing signal of a circuit breaker or a recovery signal of the single-phase grounding fault of the power grid;
according to the past fault analysis experience, no matter the electromagnetic voltage transformer is a three-phase split type or a three-phase five-column type, the primary winding burnout fault usually occurs on 1-2 windings firstly, but the phenomenon is theoretically explained, the PT overcurrent is usually caused by iron core saturation, the iron core saturation is usually excited by overvoltage, and the three-phase overvoltage and the saturation degree are usually not synchronous. By combining the theory and practical experience, the fact that a current sensor is installed at the neutral point of the three-phase transformer is considered, and the current amplitude of the neutral point can be reflected by the rise of the current amplitude of the neutral point no matter the overcurrent is caused by single-phase or two-phase saturation. The common electromagnetic voltage transformers have different types, and for a three-phase five-column voltage transformer, the tail ends of three-phase windings are not respectively led out, and only neutral point ground current is given, so that the structural requirement of a typical PT (potential transformer) of the three-phase five-column voltage transformer is met by adopting a method of monitoring the ground current only. The current sensor frequency band requirement meets the measurement requirements of fundamental frequency and higher harmonic, and the measurement precision requirement is met in a low frequency range. The convenience of installation and removal should also be considered when selecting the current sensor form.
PT saturation and its resulting over-current burnout are often excited by two types of transient processes of the grid: 1. the transformer is easily saturated during switching-on and switching-off operation, particularly during switching-on and switching-off of a short bus; and 2, restoring the single-phase earth fault of the power grid. The two signals are used as trigger conditions for accelerating the monitoring speed, and the monitoring and wave recording time is adjusted, so that the overcurrent fault process of most of the transformers can be covered. Therefore, the transformer can be saturated in the transient processes of the two types of power grid systems, at the moment, the voltage and the current of the transformer are correspondingly changed, and it can be understood that the two transient processes are the inducement factors of the transformer saturation, but the fault reasons of the transformer are various and difficult to clearly analyze, so that the fault reasons of the transformer can be accurately judged according to the states of the neutral point grounding current, the zero sequence voltage characteristic quantity and the like.
202. Synthesizing the three-phase voltage to obtain open delta voltage, and extracting zero sequence voltage characteristic quantity of the open delta voltage, wherein the zero sequence voltage characteristic quantity comprises: voltage peak value, zero sequence half harmonic component amplitude and zero sequence third harmonic component amplitude;
because the transformer saturation has zero sequence characteristic, namely the line voltage keeps unchanged when in fault, the phase voltage is increased, and the open delta voltage is equal to 3 times of neutral point voltage. When the open triangle voltage is zero in normal operation, when the voltage is monitored to rise to a certain amplitude, the ground fault of a power grid system is indicated, or the transformer is saturated. Therefore, the transient process of the power grid system can be effectively reflected by obtaining the open triangular voltage.
Therefore, after the saturation of the transformer is determined, the three-phase voltages of the transformer are combined into an open triangle voltage, and three characteristic quantities are obtained: 1. a voltage peak; 2. zero sequence 1/2 subharmonic component magnitudes; 3. zero sequence third harmonic component amplitude. And comparing the three feature quantities obtained by calculation with respective preset threshold values, and when any one of the three feature quantities exceeds the threshold value, meeting the voltage abnormity alarm condition of the transformer fault. The threshold value may be selected taking into account the following factors:
preset threshold V for voltage peakPThe open delta voltage (100V) in the case of single-phase earth fault can be selected, and when the open delta voltage reaches the value, the system is indicated to have earth fault; preset threshold V for 1/2 subharmonic component magnitudes3And preset threshold V of third harmonic component amplitude1/2Each harmonic with lower amplitude exists in the normal operation of the system, the related standard has clear requirements on harmonic components, and the triggering of the device needs to avoid the harmonic level in the normal operation. The upper limits of the two types of harmonic components can be selected according to the requirements of the relevant standards of the power quality, and a certain coefficient is multiplied to be used as a harmonic condition threshold value.
203. And correspondingly determining the fault reason of the mutual inductor according to the judgment result after judging that the zero sequence voltage characteristic quantity and/or the neutral point grounding current meet the alarm condition.
In this embodiment, specifically, the step of determining that the zero-sequence voltage characteristic quantity and/or the neutral point ground current satisfy the alarm condition is:
judging that any one zero-sequence voltage characteristic quantity is greater than a corresponding preset voltage threshold value in the voltage peak value, the zero-sequence half harmonic component amplitude value and the zero-sequence third harmonic component amplitude value, and then meeting the voltage abnormity warning condition;
and/or
And judging that the neutral point grounding current is larger than a preset current threshold value, and continuing for a preset time period (which can be set in advance according to actual requirements) without attenuation, so that the overcurrent alarm condition is met.
In this embodiment, because there are three zero-sequence voltage characteristic quantities, any one of which is greater than the corresponding preset voltage threshold may satisfy the voltage abnormality alarm condition, and the neutral grounding current is greater than the preset current threshold, and may satisfy the overcurrent alarm condition after continuing for the preset time period and not attenuating, it should be noted that these two conditions may only satisfy one condition, or may also satisfy both conditions, so that the following five conditions may occur in the determination result, and the cause of the fault of each transformer may be correspondingly determined:
(1) if the zero sequence third harmonic component amplitude is larger than the corresponding preset voltage threshold value, the neutral point grounding current is larger than the preset current threshold value, and the preset time period is continued without attenuation, determining that the fault of the mutual inductor is caused by overcurrent caused by high-frequency resonance;
(2) if the zero sequence half harmonic component amplitude is larger than the corresponding preset voltage threshold value, the neutral point grounding current is larger than the preset current threshold value, and the preset time period is continued without attenuation, determining that the fault of the transformer is caused by overcurrent caused by frequency division resonance;
(3) if the voltage peak value is larger than the corresponding preset voltage threshold value, and the neutral point grounding current is larger than the preset current threshold value, and lasts for a preset time period without attenuation, determining that the fault of the mutual inductor is caused by overcurrent caused by power frequency resonance;
(4) if the overcurrent alarm condition is met and the voltage abnormity alarm condition is not met, determining that the fault of the transformer is caused by a short circuit or a load;
(5) and if the overvoltage abnormal alarm condition is met and the overcurrent alarm condition is not met, determining that the fault of the mutual inductor is caused by insulation defects.
For the above fault cause (4), in addition to the transformer overcurrent caused by saturation, the transformer itself may cause overcurrent due to winding insulation defect, load characteristic variation, load lead short circuit, wiring error and other factors. The overcurrent value is increased gradually and reaches hundreds of times of rated primary current, and the transformer is burnt after the transformer operates for a few minutes. The overcurrent is independent of the nonlinear characteristic of the transformer, so that the overcurrent is independent of the transient voltage.
According to the invention, the neutral point current and the three-phase voltage of the mutual inductor are monitored, the zero-sequence voltage characteristic quantity and the neutral point current are used as variables to judge whether the mutual inductor fails or not, and finally, the fault reason of the mutual inductor is determined according to the judgment result, so that the voltage and the current in the transient process of the mutual inductor can be monitored when the mutual inductor fails, and the fault reason of the mutual inductor is accurately analyzed on the basis of the voltage and the current obtained through monitoring.
In the above, a method for analyzing a fault of an electromagnetic voltage transformer according to the present invention is described in detail, and referring to fig. 2, an embodiment of an apparatus for analyzing a fault of an electromagnetic voltage transformer according to the present invention includes:
the acquisition module 201 is configured to acquire a neutral point grounding current of a primary winding of the transformer and a three-phase voltage of a secondary winding of the transformer after acquiring a transient process signal for saturating the transformer;
the calculating module 202 is used for calculating the three-phase voltage to obtain a zero-sequence voltage characteristic quantity of the mutual inductor;
and the determining module 203 is configured to correspondingly determine a fault reason of the transformer according to a determination result after the zero sequence voltage characteristic quantity and/or the neutral point ground current are judged to meet the alarm condition.
Furthermore, a transient process signal for saturating the mutual inductor is a closing signal of a circuit breaker or a recovery signal of the single-phase earth fault of the power grid.
Furthermore, the calculation module 202 is further configured to synthesize the three-phase voltages to obtain open delta voltages, and extract zero-sequence voltage characteristic quantities of the open delta voltages.
Further, the zero sequence voltage characteristic quantity includes: voltage peak value, zero sequence half harmonic component amplitude and zero sequence third harmonic component amplitude.
Still further, the determining module 203 comprises:
the judging unit is used for judging whether the zero sequence voltage characteristic quantity and/or the neutral point grounding current meet the alarm condition;
the determining unit is used for correspondingly determining the fault reason of the mutual inductor according to the judging result;
the judging unit is also used for judging that any one zero sequence voltage characteristic quantity is larger than a corresponding preset voltage threshold value in the voltage peak value, the zero sequence half harmonic component amplitude value and the zero sequence third harmonic component amplitude value, and then the voltage abnormity warning condition is met;
and/or
And judging that the neutral point grounding current is larger than a preset current threshold value, and if the neutral point grounding current lasts for a preset time period and is not attenuated, the overcurrent alarm condition is met.
Still further, the determination unit is further configured to:
if the zero sequence third harmonic component amplitude is larger than the corresponding preset voltage threshold value, the neutral point grounding current is larger than the preset current threshold value, and the preset time period is continued without attenuation, determining that the fault of the mutual inductor is caused by overcurrent caused by high-frequency resonance;
if the zero sequence half harmonic component amplitude is larger than the corresponding preset voltage threshold value, the neutral point grounding current is larger than the preset current threshold value, and the preset time period is continued without attenuation, determining that the fault of the transformer is caused by overcurrent caused by frequency division resonance;
if the voltage peak value is larger than the corresponding preset voltage threshold value, and the neutral point grounding current is larger than the preset current threshold value, and lasts for a preset time period without attenuation, determining that the fault of the mutual inductor is caused by overcurrent caused by power frequency resonance;
if the overcurrent alarm condition is met and the voltage abnormity alarm condition is not met, determining that the fault of the transformer is caused by a short circuit or a load;
and if the overvoltage abnormal alarm condition is met and the overcurrent alarm condition is not met, determining that the fault of the mutual inductor is caused by insulation defects.
Another embodiment of the present invention provides an electromagnetic voltage transformer fault analysis apparatus, including: a memory, and a processor coupled to the memory;
the processor is configured to perform the electromagnetic voltage transformer fault analysis method described above based on instructions stored in the memory device.
The invention also relates to a computer-readable medium, on which a computer program is stored which, when being executed by a processor, carries out the electromagnetic voltage transformer fault analysis method described above.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. A fault analysis method for an electromagnetic voltage transformer is characterized by comprising the following steps:
after a transient process signal for saturating the mutual inductor is obtained, a current sensor is arranged at a neutral point of a three-phase mutual inductor to collect neutral point grounding current of a primary winding of the mutual inductor in real time, and three-phase voltage of a secondary winding of the mutual inductor is collected in real time;
calculating the three-phase voltage to obtain a zero-sequence voltage characteristic quantity of the mutual inductor;
after the zero sequence voltage characteristic quantity and the neutral point grounding current are judged to meet the alarm condition, correspondingly determining the fault reason of the mutual inductor according to the judgment result;
the zero sequence voltage characteristic quantity comprises: voltage peak value, zero sequence half harmonic component amplitude and zero sequence third harmonic component amplitude;
the specific steps of judging that the zero sequence voltage characteristic quantity and the neutral point grounding current meet the alarm condition are as follows:
judging that any one of the zero-sequence voltage characteristic quantities is larger than a corresponding preset voltage threshold value in the voltage peak value, the zero-sequence half harmonic component amplitude value and the zero-sequence third harmonic component amplitude value, and then meeting a voltage abnormity warning condition;
and
and judging that the neutral point grounding current is larger than a preset current threshold value, and if the neutral point grounding current lasts for a preset time period and is not attenuated, the overcurrent alarm condition is met.
2. The method according to claim 1, wherein the transient process signal for saturating the transformer is a closing signal of a circuit breaker or a recovery signal of a single-phase earth fault of a power grid.
3. The method for analyzing the fault of the electromagnetic voltage transformer according to claim 1, wherein the step of calculating the three-phase voltage to obtain the zero-sequence voltage characteristic quantity of the transformer specifically comprises the following steps:
and synthesizing the three-phase voltage to obtain an open delta voltage, and extracting the zero sequence voltage characteristic quantity of the open delta voltage.
4. The method for analyzing the fault of the electromagnetic voltage transformer according to claim 3, wherein the correspondingly determining the fault reason of the transformer according to the judgment result specifically comprises:
if the zero sequence third harmonic component amplitude is larger than a corresponding preset voltage threshold value, the neutral point grounding current is larger than a preset current threshold value, and a preset time period is continued without attenuation, determining that the fault of the transformer is caused by overcurrent caused by high-frequency resonance;
if the zero sequence half harmonic component amplitude is larger than the corresponding preset voltage threshold value, the neutral point grounding current is larger than the preset current threshold value, and the preset time period is continued without attenuation, determining that the fault of the transformer is caused by overcurrent caused by frequency division resonance;
if the voltage peak value is larger than the corresponding preset voltage threshold value, and the neutral point grounding current is larger than the preset current threshold value, and lasts for a preset time period without attenuation, determining that the fault of the transformer is caused by overcurrent caused by power frequency resonance;
if the overcurrent alarm condition is met and the voltage abnormity alarm condition is not met, determining that the fault of the transformer is caused by a short circuit or a load;
and if the voltage abnormity warning condition is met and the overcurrent warning condition is not met, determining that the fault of the transformer is caused by insulation defect.
5. An electromagnetic type voltage transformer fault analysis device, characterized by includes:
the acquisition module is used for acquiring neutral point grounding current of a primary winding of the mutual inductor and three-phase voltage of a secondary winding of the mutual inductor after acquiring a transient process signal for saturating the mutual inductor;
the calculation module is used for calculating the three-phase voltage to obtain the zero-sequence voltage characteristic quantity of the mutual inductor;
the determining module is used for correspondingly determining the fault reason of the mutual inductor according to the judging result after judging that the zero sequence voltage characteristic quantity and the neutral point grounding current meet the alarm condition;
the zero sequence voltage characteristic quantity comprises: voltage peak value, zero sequence half harmonic component amplitude and zero sequence third harmonic component amplitude;
the specific steps of judging that the zero sequence voltage characteristic quantity and the neutral point grounding current meet the alarm condition are as follows:
judging that any one of the zero-sequence voltage characteristic quantities is larger than a corresponding preset voltage threshold value in the voltage peak value, the zero-sequence half harmonic component amplitude value and the zero-sequence third harmonic component amplitude value, and then meeting a voltage abnormity warning condition;
and
and judging that the neutral point grounding current is larger than a preset current threshold value, and if the neutral point grounding current lasts for a preset time period and is not attenuated, the overcurrent alarm condition is met.
6. The electromagnetic voltage transformer fault analysis device of claim 5, wherein the transient process signal for saturating the transformer is a closing signal of a circuit breaker or a recovery signal of a single-phase earth fault of a power grid.
7. An electromagnetic type voltage transformer fault analysis device, characterized by includes: a memory, and a processor coupled to the memory;
the processor is configured to execute the electromagnetic voltage transformer fault analysis method of any one of claims 1 to 4 based on instructions stored in the memory device.
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