CN108631281B - Resonance eliminating method for ferromagnetic resonance - Google Patents
Resonance eliminating method for ferromagnetic resonance Download PDFInfo
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- CN108631281B CN108631281B CN201810483332.8A CN201810483332A CN108631281B CN 108631281 B CN108631281 B CN 108631281B CN 201810483332 A CN201810483332 A CN 201810483332A CN 108631281 B CN108631281 B CN 108631281B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/005—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection avoiding undesired transient conditions
- H02H9/007—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection avoiding undesired transient conditions avoiding or damping oscillations, e.g. fenoresonance or travelling waves
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/028—Current limitation by detuning a series resonant circuit
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- Emergency Protection Circuit Devices (AREA)
Abstract
The invention provides a resonance elimination method of ferromagnetic resonance, which comprises the steps of judging whether excitation inrush current exceeds a preset current amplitude value; if the current exceeds the threshold value, further calculating the slope of the rising edge of the magnetizing inrush current; and then comparing and judging the rising edge slope of the magnetizing inrush current with a preset slope, and when the rising edge slope of the magnetizing inrush current is greater than the preset slope, generating ferromagnetic resonance of the electromagnetic voltage transformer. And finally, comparing the counter with a third preset value, if the counter meets the third preset value, closing the control switch, and carrying out harmonic elimination treatment on the electromagnetic voltage transformer by the harmonic elimination device. The application provides a ferroresonance's harmonic elimination method with harmonic elimination resistance lug connection on the opening triangle return circuit, can accurate, eliminate ferroresonance fast to effectively improve ferroresonance's harmonic elimination efficiency. And the amplitude of the excitation surge current and the slope of the rising edge are used as conditions for distinguishing ferromagnetic resonance and other abnormal states, so that the resonance elimination device is prevented from frequently acting.
Description
Technical Field
The application relates to the technical field of electric power system safety control, in particular to a resonance elimination method for ferromagnetic resonance.
Background
In a 6-35 kV power distribution network, a neutral point of the system is not grounded, a bus is connected with a measuring and monitoring system ground-insulated electromagnetic voltage Transformer (PT), when a bus switch is switched on, single-phase arc grounding automatically disappears in a circuit or system load is changed violently, a ferromagnetic resonance phenomenon is initiated between the PT and a ground capacitor of a three-phase lead in a transient impact process, system overvoltage and overcurrent in the PT are caused, and therefore weak-insulated equipment in the system is subjected to ground flashover and PT high-voltage fuse fusing, and even PT is burnt.
At present, the protection mode for the occurrence of ferromagnetic resonance in the related art mainly adopts: a resonance eliminator is additionally arranged at a primary neutral point of the electromagnetic voltage transformer, or a damping resistor is additionally arranged on a zero sequence voltage loop of the electromagnetic voltage transformer, a microcomputer secondary resonance eliminating device is additionally arranged, and zero sequence voltage, voltage waveform of each phase and the like are detected. The resonance eliminator is additionally arranged at a primary neutral point of the electromagnetic voltage transformer, namely the resonance eliminator is connected to the sequential neutral points of the electromagnetic voltage transformer, and the resonance elimination of the generated ferromagnetic resonance is realized through the resonance eliminator.
However, although the mode of additionally installing the resonance eliminator at the primary central point of the electromagnetic voltage transformer can prevent ferromagnetic resonance between three-phase voltage and the ground, which is extremely easy to generate in a system, the resonance elimination effect on power frequency resonance caused by wire breakage is poor, and adverse phenomena such as voltage rise of a neutral point of the electromagnetic voltage transformer, insulation breakdown of the tail end of the electromagnetic voltage transformer and the like are easily caused, so that the resonance eliminator loses effect; the damping resistor is additionally arranged, so that the harmonic elimination effect is influenced due to the heating of the damping resistor; the method for detecting zero sequence voltage and three-phase voltage waveform by adopting a microcomputer secondary resonance eliminator device is difficult to distinguish power frequency resonance, and the method has low resonance elimination speed, can not realize quick resonance elimination, and is easy to cause the problem of failure in resonance elimination due to insufficient damping of a resonance circuit.
Therefore, by adopting the existing harmonic elimination mode, the harmonic elimination time can be prolonged, the harmonic elimination cost can be increased, the harmonic elimination efficiency can be greatly influenced, the equipment is frequently damaged, and the safe and stable operation of the power grid and the equipment is seriously threatened.
Disclosure of Invention
In order to solve the problems in the related art, the invention provides a resonance elimination method of ferromagnetic resonance.
The invention provides a resonance elimination method of ferromagnetic resonance, which comprises the following steps:
s10, detecting the excitation inrush current between the neutral point of the electromagnetic voltage transformer and the high-voltage damping resistor through the current transformer, and judging whether the electromagnetic voltage transformer generates ferromagnetic resonance;
s11, calculating the rising edge slope of the magnetizing inrush current according to the magnetizing inrush current;
s12, judging whether the slope of the rising edge of the magnetizing inrush current is greater than a preset slope or not, and if the slope of the rising edge of the magnetizing inrush current is greater than the preset slope, performing S13; if the slope of the rising edge of the magnetizing inrush current is not greater than the preset slope, returning to the step S10;
s13, judging whether the counter meets a third preset value or not, if so, controlling a control switch connected in series with a resonance elimination resistor to be closed, and performing resonance elimination processing on the electromagnetic voltage transformer; and if the counter does not meet the third preset value, returning to the step S10.
Optionally, detecting an inrush current between the neutral point of the electromagnetic voltage transformer and the high-voltage damping resistor through the current transformer, and determining whether the inrush current is greater than a preset current amplitude includes:
s11, judging whether the current transformer detects an excitation surge current between the neutral point of the electromagnetic voltage transformer and the high-voltage damping resistor;
s12, if the magnetizing inrush current is detected, the step S13 is carried out, and if the magnetizing inrush current is not detected, the step S11 is returned;
s13, judging whether the magnetizing inrush current is larger than a preset current amplitude value or not, and if so, performing the step S12; if not, returning to step S11.
Optionally, the preset current amplitude is 0.2A to 1A.
Optionally, the preset slope is 0.2A/ms.
Optionally, the third preset value is that the value of the counter of the first timer is not greater than two times within 20 s.
Optionally, the controlling of the closing of the control switch connected in series with the resonance elimination resistor, and the resonance elimination of the electromagnetic voltage transformer includes:
starting a second timer to start timing;
and judging whether the second timer reaches a fourth preset value, and disconnecting the control switch when the second timer reaches the fourth preset value.
Optionally, the fourth preset value is 80-120 ms.
The invention provides a resonance elimination method of ferromagnetic resonance, which comprises the steps of judging whether excitation inrush current exceeds a preset current amplitude value; if the current exceeds the threshold value, further calculating the slope of the rising edge of the magnetizing inrush current; and then comparing and judging the rising edge slope of the magnetizing inrush current with a preset slope, and when the rising edge slope of the magnetizing inrush current is greater than the preset slope, generating ferromagnetic resonance of the electromagnetic voltage transformer. And finally, comparing the counter with a third preset value, if the counter meets the third preset value, closing the control switch, and carrying out harmonic elimination treatment on the electromagnetic voltage transformer by the harmonic elimination device.
The invention provides a resonance elimination method of ferromagnetic resonance, which judges whether a control switch connected in series with a resonance elimination resistor is closed or not according to the judgment of excitation surge current, so that the resonance elimination resistor and an opening triangular loop form a series loop, the resonance elimination resistor increases the damping of a primary loop of an electromagnetic voltage transformer, and the ferromagnetic resonance of the electromagnetic voltage transformer is eliminated rapidly. And the amplitude of the excitation surge current and the slope of the rising edge are used as conditions for distinguishing ferromagnetic resonance and other abnormal states, so that the resonance elimination device is prevented from frequently acting. The resonance elimination method of the ferromagnetic resonance overcomes the problems that a microcomputer secondary resonance elimination device cannot realize quick resonance elimination and resonance elimination fails due to insufficient damping of a resonance loop.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.
Fig. 1 is a schematic flow chart of a method for eliminating ferroresonance according to an embodiment of the present invention;
FIG. 2 is a partial schematic flow chart of a method for eliminating ferroresonance provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram of a ferroresonance detuning device for use in an embodiment of the invention;
fig. 4 is a schematic diagram of a slope of a rising edge of a magnetizing inrush current in a method for detuning a ferroresonance according to an embodiment of the present invention.
Illustration of the drawings:
wherein, 1-a current transformer; 2-harmonic elimination resistance; 3-control the switch; 4-a resonance judgment module; 5-a power supply module; 6-harmonic elimination module.
Detailed Description
The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the drawings in the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all 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.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present application and the scope of the present invention is accordingly not limited to the specific embodiments disclosed below.
Fig. 3 is a schematic structural diagram of a ferroresonance resonance elimination device used in an embodiment of the present invention. As shown in fig. 3, the apparatus may include a power supply module 5, a resonance determination module 4, a resonance elimination module 6, and a current transformer 1 (CT).
In the ferromagnetic resonance elimination device, a power module 5 is electrically connected to the resonance judgment module 4 and the resonance elimination module 6 respectively, so as to provide power for the resonance judgment module 4 and the resonance elimination module 6, and the power module 5 can be directly connected to a mains supply, the resonance judgment module 4 can be a CPU (Central Processing Unit) or a PLC (programmable logic controller), the resonance judgment module 4 is electrically connected to the resonance elimination module 6, and is used for controlling the resonance elimination module 6 to perform resonance elimination; the current transformer 1 is used to be electrically connected to a connecting wire between the neutral point of the electromagnetic voltage transformer and the ground, so that the current transformer 1 measures zero sequence current (i.e. the sum of three-phase exciting currents of the electromagnetic voltage transformer).
In order to realize ferromagnetic resonance of an electromagnetic voltage transformer in a power distribution network, the resonance elimination module 6 at least comprises a resonance elimination resistor 2 and a control switch 3, two ends of the resonance elimination resistor 2 are connected to two ends of an open triangular loop of the electromagnetic voltage transformer in series, the control switch 3 is connected between the resonance elimination resistor 2 and the open triangular loop in series, namely the open triangular loop, the resonance elimination resistor 2 and the control switch 3 form a series loop, and the open triangular loop, the resonance elimination resistor 2 and the control switch 3 form a closed or opened series loop through the on-off of the control switch 3. In the embodiment of the present disclosure, the resonance determining module 4 is electrically connected to the control switch 3, so that the resonance determining module 4 controls the on/off of the control switch 3. The two ends of the open triangular loop of the electromagnetic voltage transformer are connected through the resonance elimination resistor 2, so that the sequential loop damping of the electromagnetic voltage transformer is increased through the resistance value of the resonance elimination resistor 2, and the ferromagnetic resonance generated by the electromagnetic voltage transformer is eliminated.
The invention provides a method for eliminating ferroresonance as shown in fig. 1, which comprises the following steps:
in step S10, a magnetizing inrush current between the neutral point of the electromagnetic voltage transformer and the high-voltage damping resistor is detected by the current transformer 1, and it is determined whether the magnetizing inrush current is greater than a preset current amplitude.
When the ferromagnetic resonance of the electromagnetic voltage transformer does not occur, the open triangular loop of the electromagnetic voltage transformer does not generate induced current, so that the magnitude of the magnetizing inrush current between the neutral point and the high-voltage damper of the electromagnetic voltage transformer is detected through the current transformer 1. And then comparing the detected magnetizing inrush current with a preset current amplitude value, and judging whether the detected magnetizing inrush current exceeds the preset current amplitude value.
In the embodiments disclosed in the present invention, under normal circumstances, when the electromagnetic voltage transformer does not generate ferromagnetic resonance, the electromagnetic voltage transformer still has
The magnetizing inrush current is only small at this time. When the magnetizing inrush current is detected to be larger than the preset current amplitude value of 0.2-1A, it is judged that ferromagnetic resonance is possibly generated by the electromagnetic voltage transformer.
A part of the flow chart provided by the embodiment of the invention is shown in fig. 2. As shown in fig. 2, the step S10 specifically includes the following steps:
step S101, judging whether the current transformer 1 detects an excitation surge current between a neutral point of the electromagnetic voltage transformer and a high-voltage damping resistor; if the magnetizing inrush current is detected, performing step S102; if the magnetizing inrush current is not detected, the detection is continued.
Step S102, after the magnetizing inrush current is detected, the resonance determination module 4 determines whether the magnetizing inrush current exceeds a preset current amplitude, and if the magnetizing inrush current exceeds the preset current amplitude, the step S11 is performed. If the resonance judgment module 4 judges that the magnetizing inrush current does not exceed the preset current amplitude, it can be judged that the electromagnetic voltage transformer does not have ferromagnetic resonance.
When the detected magnetizing inrush current is larger than the preset current amplitude, the step S11 is performed to calculate the rising edge slope of the magnetizing inrush current. As shown in fig. 4, a schematic diagram of a slope of a rising edge of a magnetizing inrush current for a method of detuning a ferroresonance according to an embodiment of the present invention is provided.
After the rising edge slope of the magnetizing inrush current is calculated, in step S12, comparing the rising edge slope of the magnetizing inrush current with a preset slope, and if the rising edge slope of the magnetizing inrush current is greater than the preset slope, determining that ferromagnetic resonance occurs in the electromagnetic voltage transformer; and if the slope of the rising edge of the magnetizing inrush current is not greater than the preset slope, returning to the step S10.
In the embodiment disclosed in the present invention, the preset slope is a preset value, and in the specific implementation process, the preset slope is 0.2A/ms. And when the calculated slope of the rising edge of the excitation inrush current is greater than or equal to 0.2A/ms, determining that ferromagnetic resonance occurs in the electromagnetic voltage transformer. And if the calculated slope of the rising edge of the excitation inrush current is less than 0.2A/ms, determining that the electromagnetic voltage transformer has no ferromagnetic resonance, returning to the step S10, and continuously detecting the excitation inrush current.
When it is determined that the ferromagnetic resonance of the electromagnetic transformer occurs, in step S13, it is determined whether the counter satisfies a third preset value. In step S14, when the counter satisfies the third preset value, it is further determined whether the control switch 3 connected in series with the resonance elimination resistor 2 needs to be closed through the counter and the timer, so as to perform resonance elimination on the electromagnetic voltage transformer. And starting a first timer and a counter, judging whether the first timer is within 20s and the value of the counter is greater than 2, indicating that the resonance elimination processing of the ferromagnetic resonance generated by the electromagnetic voltage transformer is performed at least twice within 20s, and not performing the resonance elimination processing when the value of the counter is greater than 2 within 20s in order to avoid frequent actions of the resonance elimination device. When the value of the counter in 20s is larger than 2, the harmonic elimination device enters a protection time, and in the protection time, if the slope of the rising edge of the excitation inrush current is larger than a preset value, harmonic elimination is not carried out. Typically, the guard time is 5 min. The counter counts once for each detuning process. And when the counter does not meet the third preset value, returning to the step S10.
Once the resonance elimination device starts the resonance elimination process, a second timer is started, the duration of the resonance elimination action is recorded, and when the duration of the resonance elimination action reaches a fourth preset value, the control switch 3 is switched off. Typically, the fourth predetermined period of time for the detuning action is 80-120 ms.
The invention provides a resonance elimination method of ferromagnetic resonance, which comprises the steps of judging whether excitation inrush current exceeds a preset current amplitude value; if the current exceeds the threshold value, further calculating the slope of the rising edge of the magnetizing inrush current; and then comparing and judging the rising edge slope of the magnetizing inrush current with a preset slope, and when the rising edge slope of the magnetizing inrush current is greater than the preset slope, generating ferromagnetic resonance of the electromagnetic voltage transformer. And finally, comparing the counter with a third preset value, if the counter meets the third preset value, closing the control switch 3, and carrying out harmonic elimination treatment on the electromagnetic voltage transformer by the harmonic elimination device.
The invention provides a resonance elimination method of ferromagnetic resonance, which judges whether a control switch 3 connected with a resonance elimination resistor 2 in series is closed or not according to the judgment of excitation surge current, so that the resonance elimination resistor 2 and an open triangular loop form a series loop, the resonance elimination resistor 2 is used for increasing the damping of a primary loop of an electromagnetic voltage transformer, and therefore, the ferromagnetic resonance of the electromagnetic voltage transformer is eliminated rapidly, and the resonance elimination resistor 2 is directly connected on the open triangular loop, so that the ferromagnetic resonance can be eliminated accurately and rapidly, and the resonance elimination efficiency of the ferromagnetic resonance is improved effectively. And the amplitude of the excitation surge current and the slope of the rising edge are used as conditions for distinguishing ferromagnetic resonance and other abnormal states, so that the resonance elimination device is prevented from frequently acting. The resonance elimination method of the ferromagnetic resonance overcomes the problems that a microcomputer secondary resonance elimination device cannot realize quick resonance elimination and resonance elimination fails due to insufficient damping of a resonance loop.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (6)
1. A method of detuning a ferroresonance, comprising:
s10, detecting the magnetizing inrush current between the neutral point of the electromagnetic voltage transformer and the high-voltage damping resistor through the current transformer, and judging whether the magnetizing inrush current is larger than a preset current amplitude value;
detecting the magnetizing inrush current between the neutral point of the electromagnetic voltage transformer and the high-voltage damping resistor through the current transformer, and judging whether the magnetizing inrush current is greater than a preset current amplitude value or not comprises the following steps:
s101, judging whether the current transformer detects an excitation surge current between a neutral point and a high-voltage damping resistor of the electromagnetic voltage transformer; if the magnetizing inrush current is detected, performing step S102;
s102, judging whether the magnetizing inrush current is larger than a preset current amplitude value or not, and if so, performing step S11; if the current amplitude is not larger than the preset current amplitude, returning to the step S101;
s11, when the magnetizing inrush current is larger than a preset current amplitude, calculating the rising edge slope of the magnetizing inrush current;
s12, judging whether the slope of the rising edge of the magnetizing inrush current is greater than a preset slope or not, and if the slope of the rising edge of the magnetizing inrush current is greater than the preset slope, performing S13; if the slope of the rising edge of the magnetizing inrush current is not greater than the preset slope, returning to the step S10;
s13, judging whether the counter meets a third preset value or not;
s14, if the counter meets a third preset value, controlling a control switch connected in series with a resonance elimination resistor to be closed, and performing resonance elimination processing on the electromagnetic voltage transformer; and if the counter does not meet the third preset value, returning to the step S10.
2. The method of claim 1, wherein the predetermined current amplitude is 0.2A to 1A.
3. A method of detuning a ferroresonance according to claim 1, wherein the predetermined slope is 0.2A/ms.
4. The method of claim 1, wherein the third predetermined value is such that the first timer does not count more than twice within 20 s.
5. The ferroresonance elimination method of claim 1, wherein the controlling of the closing of a control switch connected in series with a resonance elimination resistor, and the resonance elimination of the electromagnetic voltage transformer comprises:
starting a second timer to start timing;
and judging whether the second timer reaches a fourth preset value, and disconnecting the control switch when the second timer reaches the fourth preset value.
6. Method for detuning a ferroresonance according to claim 5, wherein the fourth predetermined value is 80-120 ms.
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| CN202455058U (en) * | 2011-12-22 | 2012-09-26 | 鞍钢股份有限公司 | Resonance overvoltage suppression device for primary side neutral point ungrounded power grid |
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2018
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| CN202455058U (en) * | 2011-12-22 | 2012-09-26 | 鞍钢股份有限公司 | Resonance overvoltage suppression device for primary side neutral point ungrounded power grid |
| CN106099857A (en) * | 2016-08-17 | 2016-11-09 | 云南电网有限责任公司电力科学研究院 | Detection zero-sequence current pulse width conforming ferromagnetic resonance harmonic elimination method |
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