CN108306274A - A kind of control method that ferromagnetic resonance for electromagnetic voltage transformer is eliminated - Google Patents
A kind of control method that ferromagnetic resonance for electromagnetic voltage transformer is eliminated Download PDFInfo
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- CN108306274A CN108306274A CN201810154844.XA CN201810154844A CN108306274A CN 108306274 A CN108306274 A CN 108306274A CN 201810154844 A CN201810154844 A CN 201810154844A CN 108306274 A CN108306274 A CN 108306274A
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- frequency
- resonance
- voltage transformer
- eliminated
- control method
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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
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
Abstract
The invention discloses the control methods that a kind of ferromagnetic resonance for electromagnetic voltage transformer is eliminated, three frequency division included in voltage transformer open-triangular winding voltage is calculated in real time, two divided-frequency and frequency tripling harmonic component and power frequency component, when its value is more than the setting value of corresponding resonance criterion, difference according to resonant frequency, to being connected to the electronic switch harmonic elimination circuit at voltage transformer open-triangular winding both ends, corresponding single conduction duration is respectively set, adjacent conducting state interval time and maximum triggering and conducting number, control method is connected by the pulsed of differentiation, improve harmonic elimination validity and success rate.
Description
Technical field
The present invention relates to field of power, relate more specifically to the identification of ferromagnetic resonance for electromagnetic voltage transformer and disappear
Except method.
Background technology
In neutral point non-direct grounding system, some are used to measure the voltage transformer of insulation against ground, primary side winding
Neutral-point solid ground, when occurring that unloaded busbar closes a floodgate, singlephase earth fault disappears or system loading acute variation, electricity
The magnetizing inductance of pressure mutual inductor will appear nonlinear change, may form parameter with system direct-to-ground capacitance and match, to cause
Ferromagnetic resonance phenomenon causes system overvoltage and TV overcurrent, in turn results in insulation breakdown ground connection or phase-to phase fault and TV is molten
Silk fusing burns or explodes, or even there is also the failures such as Explosion of on Arrester, weak isolating flashover, line-selected earthing device malfunction, sternly
Ghost image acoustic system safe operation.
Cause the disturbance situation of ferromagnetic resonance more, wherein most common disturbance situation is singlephase earth fault in short-term, in list
During phase earth fault, the voltage of unearthed phase is increased to line voltage, and circuit, busbar direct-to-ground capacitance are filled with opposite with line voltage
After answering charge, earth fault to disappear, line voltage distribution restores, and passes through voltage transformer in the excess charge short time on direct-to-ground capacitance
Neutral point discharges, and voltage transformer is caused to be saturated, if the magnetizing inductance after saturation meets matching relationship with system direct-to-ground capacitance
Resonance may be excited.
A kind of common counter-measure is installing microcomputer harmonic elimination device at present, and the basic principle of the device is：Device accesses
Voltage transformer secondary open delta voltage works as voltage by voltage harmonic feature and harmonic component size identification ferromagnetic resonance
When ferromagnetic resonance occurs for mutual inductor, repeatedly triggered in short-term by electronic switching device at voltage transformer open-triangular winding short
Connect (or the damping resistance R that access is small△), resonance Production conditions are destroyed, to eliminate resonance.
According to U.S. H.A.Peterson and industry technology personnel's experimental study, with system capacitance to earth and voltage
Mutual inductor excitation induction reactance ratio (Xco/XLe) increase, in corresponding disturbance, voltage transformer may divide successively
Resonance, industrial frequency resonance and high-frequency resonant.
After existing microcomputer harmonic elimination device identifies ferromagnetic resonance, the conducting cut-off method of electronic switching device is more simple
It is single, for the resonance of different frequency, identical turn-on time, conducting state interval time (i.e. turn-off time) are preset, these dresses
Set that harmonic elimination difference on effect in applying at the scene is larger, and harmonic elimination speed is slow, and whole harmonic elimination success rate is relatively low.Moreover, some devices
Not default maximum conducting number limitation, since ferromagnetic resonance may exist for a long time when harmonic elimination is unsuccessful, may lead to device
Open delta circuit is persistently triggered according to preset conducting cut-off method, larger pulsed harmonic elimination is flowed through in device harmonic elimination circuit
Short circuit current may lead to the hardware scaling loss or component damage of harmonic elimination circuit in the case where the long period acts on.
Microcomputer harmonic elimination device triggers harmonic elimination control after identifying ferromagnetic resonance, and common harmonic elimination control method is shown in Fig. 4.For
The resonance of different frequency presets identical turn-on time tonFor 0.5s, conducting state interval time toffIt is 0.5s (when turning off
Between), until number is connected in preset maximum harmonic elimination, or until resonance phenomena disappears.
Invention content
The purpose of the present invention is：A kind of ferromagnetic resonance elimination control method of voltage transformer secondary harmonic elimination apparatus is provided,
For different resonant frequencies, differentiation harmonic elimination control method is used, to improve the validity and success rate of harmonic elimination.
In order to achieve the above objectives, the present invention provides the controlling parties that a kind of ferromagnetic resonance for electromagnetic voltage transformer is eliminated
Method differentiates ferromagnetic resonance according to voltage transformer secondary voltage characteristic, for different resonant frequencies, is respectively set different
The on or off that turn-on parameter control is connected to the electronic switch harmonic elimination circuit at voltage transformer open-triangular winding both ends is come
Ferromagnetic resonance is eliminated, the turn-on parameter includes：Single conduction duration, adjacent conducting state interval time.
Further, the turn-on parameter further includes maximum triggering and conducting number.
Further, by calculate in real time three frequency division included in voltage transformer open-triangular winding voltage, two points
Frequency and frequency tripling harmonic component and power frequency component, when the resonance that any of the above-described frequency component amplitude is more than preset respective frequencies is fixed
When being worth threshold, judge that ferromagnetic resonance has occurred in the voltage transformer.
Further, the maximum triggering and conducting number refers to after the triggering of single or multiple harmonic eliminations, if resonance-characteristic
It does not disappear yet, then after conducting number in electronic switch circuit reaches maximum triggering and conducting number, no longer carries out conducting trigger action.
Further, for three frequency division resonance and two divided-frequency resonance, single conduction duration t1, between adjacent conducting state
It is t every the time2, wherein 0.25s≤t1≤ 0.5s, 0.5s≤t2≤1s。
Further, for three frequency division resonance and two divided-frequency resonance, maximum triggering and conducting number is n1, n1≤3。
Further, for industrial frequency resonance, single conduction duration t3, adjacent conducting state interval time is t4,
In, 0.1s≤t3≤ 0.3s, 0.5s≤t4≤1s。
Further, for industrial frequency resonance, maximum triggering and conducting number is n2, n2≤6。
Further, for frequency tripling resonance, single conduction duration t5, adjacent conducting state interval time is t6,
In, 0.1s≤t5≤ 0.3s, 0.15s≤t6≤0.5s。
Further, for frequency tripling resonance, maximum triggering and conducting number is n3, n3≤12。
Further, three frequency division included in the real-time calculating voltage transformer open-triangular winding voltage, two points
Frequency and frequency tripling harmonic component and the method for power frequency component are：Using fourier algorithm according to the previous electrical cycle at current time
Voltage sample value directly calculate the virtual value of each frequency component；Or use narrow-band filtering algorithm from open delta voltage first
In filter out each frequency voltage components, then by fourier algorithm or root mean square algorithm according to the previous electrical cycle at current time
Voltage sample value calculate virtual value.
Further, by calculate in real time three frequency division included in voltage transformer open-triangular winding voltage, two points
Frequency and frequency tripling harmonic component and power frequency component, when the resonance that any of the above-described frequency component amplitude is more than preset respective frequencies is fixed
When being worth threshold, judge that the ferromagnetic resonance of the corresponding frequency has occurred in the voltage transformer.
The beneficial effects of the invention are as follows：
1, under the premise of not changing harmonic elimination basic principle and hardware device is constituted, by the electricity for optimizing microcomputer harmonic elimination device
Control method is connected in sub switch, improves the validity and success rate of harmonic elimination.
2, it is limited by the default maximum number that is connected, preventing ferromagnetic resonance from existing for a long time when harmonic elimination is unsuccessful causes to fill
Set the hardware scaling loss or component of harmonic elimination circuit caused by persistently triggering open delta circuit according to preset conducting cut-off method
Damage.
Description of the drawings
Fig. 1 is typical 10kV distribution network systems main wiring diagram；
Fig. 2 is the basic principle figure of microcomputer harmonic elimination device；
Fig. 3 is the typical identical criterion of Ferroresonance Overvoltage Caused by PT；
Fig. 4 is the common harmonic elimination control method schematic diagram of microcomputer harmonic elimination device；
Fig. 5 is microcomputer harmonic elimination device harmonic elimination control method schematic diagram provided by the invention.
Specific implementation mode
Below with reference to attached drawing and specific embodiment, technical scheme of the present invention is described in detail.
Certain typical 10kV distribution network system main wiring diagram is as shown in Figure 1.For mother's I voltage transformer of the 10kV in figure
Microcomputer harmonic elimination device is installed respectively with mother's II voltage transformer, and device introduces the open delta voltage of voltage transformer for detecting
Ferromagnetic resonance, while the control source circuit is connected to the harmonic elimination module of device, when ferromagnetic resonance occurs, according to preset control
Logic processed is connected the silicon-controlled electronic switch of harmonic elimination module, is triggered by multiple harmonic elimination, eliminates ferromagnetic resonance.Its basic principle
As shown in Figure 2.
Subharmonic Resonance is easily occurred when system direct-to-ground capacitance is larger for same voltage transformer, correspondingly, due to
It needs the excess charge of release more on system direct-to-ground capacitance, and connects the harmonic elimination circuit with voltage transformer open-triangular winding both ends
It should maintain the longer conducting triggered time；When system direct-to-ground capacitance is smaller, high-frequency resonant easily occurs, correspondingly, harmonic elimination circuit is only
It need to maintain the shorter conducting triggered time that can eliminate resonance.Therefore following technical solution proposed by the invention, it is mutual according to voltage
Sensor secondary voltage feature differentiates ferromagnetic resonance, and for different resonant frequency, different turn-on parameter control is respectively set
The on or off of the electronic switch harmonic elimination circuit at voltage transformer open-triangular winding both ends is connected to eliminate ferromagnetic resonance,
The turn-on parameter includes：Single conduction duration, adjacent conducting state interval time.The turn-on parameter further includes maximum
Triggering and conducting number.By calculate in real time three frequency division, two divided-frequency included in voltage transformer open-triangular winding voltage and
Frequency tripling harmonic component and power frequency component, when any of the above-described frequency component amplitude is more than the resonance definite value door of preset respective frequencies
When sill, judge that the ferromagnetic resonance of the corresponding frequency has occurred in the voltage transformer.When any of the above-described frequency component amplitude is more than default
Respective frequencies resonance definite value threshold when, judge that ferromagnetic resonance has occurred in the voltage transformer.
Three frequency division, two divided-frequency and frequency tripling included in the real-time calculating voltage transformer open-triangular winding voltage
Harmonic component and the method for power frequency component are：Using fourier algorithm according to the voltage sample of the previous electrical cycle at current time
Value directly calculates the virtual value of each frequency component；Or each frequency is filtered out from open delta voltage using narrow-band filtering algorithm first
Rate component of voltage, then by fourier algorithm or root mean square algorithm according to the voltage sample of the previous electrical cycle at current time
Value calculates virtual value.Microcomputer harmonic elimination device is according to the voltage sample of the previous electrical cycle at current time in the present embodiment
Value, three frequency division, two divided-frequency and frequency tripling harmonic voltage component and power-frequency voltage component virtual value are directly calculated by fourier algorithm
U17Hz、U25Hz、U150HzAnd U50HzIf any one is more than its corresponding resonance identification definite value threshold U17Hz,set、U25Hz,set、
U150Hz,setAnd U50Hz,set, then it is assumed that ferromagnetic resonance has occurred.It is illustrated in figure 3 the typical identification of Ferroresonance Overvoltage Caused by PT
Criterion, wherein U50Hz, U17Hz, U25Hz and U150Hz are respectively the power frequency point of voltage transformer open-triangular winding voltage
Amount, three frequency division component, two divided-frequency component and three times frequency component, U50Hz,set、U17Hz,set、U25Hz,Set and U150Hz,set
Respectively correspond to power frequency, the ferromagnetic resonance voltage block definite value of three frequency division, two divided-frequency and frequency tripling.
For the present embodiment, used harmonic elimination control method is shown in Fig. 5, is described in detail below：
(1) for three frequency division resonance and two divided-frequency resonance, single conduction duration t1, adjacent conducting state interval time
For t2Maximum triggering and conducting number is n1, wherein 0.25s≤t1≤ 0.5s, 0.5s≤t2≤ 1s, n1≤3；Single in the present embodiment
Conduction duration 0.5s, adjacent conducting state interval time are 1s, and maximum triggering and conducting number is 3 times；
(2) for industrial frequency resonance, single conduction duration t3, adjacent conducting state interval time is t4, maximum triggering lead
Logical number is n2, wherein 0.1s≤t3≤ 0.3s, 0.5s≤t4≤ 1s, n2≤6；Single conduction duration in the present embodiment
0.25s, adjacent conducting state interval time are 0.5s, and maximum triggering and conducting number is 6 times；
(3) for frequency tripling resonance, single conduction duration t5, adjacent conducting state interval time is t6, maximum triggering
Conducting number is n3, wherein 0.1s≤t5≤ 0.3s, 0.15s≤t6≤ 0.5s, n3≤12；Single conduction in the present embodiment
Time 0.15s, adjacent conducting state interval time are 0.35s, and maximum triggering and conducting number is 12 times.
Above example is merely illustrative of the invention's technical idea, and protection scope of the present invention cannot be limited with this, every
According to technological thought proposed by the present invention, any equivalent replacement done on the basis of technical solution or change, without departing from this
Invention protection domain.
Claims (12)
1. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer is eliminated, characterized in that according to voltage transformer secondary
Voltage characteristic differentiates ferromagnetic resonance, for different resonant frequency, different turn-on parameter control is respectively set and is connected to electricity
The on or off of the electronic switch harmonic elimination circuit at mutual inductor open-triangular winding both ends is pressed to eliminate ferromagnetic resonance, the conducting
Parameter includes：Single conduction duration, adjacent conducting state interval time.
2. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as described in claim 1 is eliminated, characterized in that institute
It further includes maximum triggering and conducting number to state turn-on parameter.
3. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 1 or 2 is eliminated, feature
It is, by calculating three frequency division, two divided-frequency and frequency tripling harmonic wave included in voltage transformer open-triangular winding voltage in real time
Component and power frequency component, when any of the above-described frequency component amplitude is more than the resonance definite value threshold of preset respective frequencies, judgement
Ferromagnetic resonance has occurred in the voltage transformer.
4. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 2 is eliminated, which is characterized in that
It is described maximum triggering and conducting number refer to by single or multiple harmonic eliminations triggering after, if resonance-characteristic does not disappear yet, electronic cutting
After conducting number in pass circuit reaches maximum triggering and conducting number, conducting trigger action is no longer carried out.
5. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 1 or 2 is eliminated, feature
It is, for three frequency division resonance and two divided-frequency resonance, single conduction duration t1, adjacent conducting state interval time is t2,
In, 0.25s≤t1≤ 0.5s, 0.5s≤t2≤1s。
6. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 2 is eliminated, characterized in that right
In three frequency division resonance and two divided-frequency resonance, maximum triggering and conducting number is n1, n1≤3。
7. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 1 or 2 is eliminated, feature
It is, for industrial frequency resonance, single conduction duration t3, adjacent conducting state interval time is t4, wherein 0.1s≤t3≤
0.3s, 0.5s≤t4≤1s。
8. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 2 is eliminated, characterized in that right
In industrial frequency resonance, maximum triggering and conducting number is n2, n2≤6。
9. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 1 or 2 is eliminated, feature
It is, for frequency tripling resonance, single conduction duration t5, adjacent conducting state interval time is t6, wherein 0.1s≤t5≤
0.3s, 0.15s≤t6≤0.5s。
10. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 2 is eliminated, characterized in that
For frequency tripling resonance, maximum triggering and conducting number is n3, n3≤12。
11. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 3 is eliminated, feature exist
In three frequency division, two divided-frequency and frequency tripling harmonic wave included in the real-time calculating voltage transformer open-triangular winding voltage
The method of component and power frequency component is：It is straight according to the voltage sample value of the previous electrical cycle at current time using fourier algorithm
Connect the virtual value for calculating each frequency component；Or each frequency electricity is filtered out from open delta voltage using narrow-band filtering algorithm first
Component is pressed, then by fourier algorithm or root mean square algorithm according to the voltage sample value meter of the previous electrical cycle at current time
Calculate virtual value.
12. the control method that a kind of ferromagnetic resonance for electromagnetic voltage transformer as claimed in claim 1 or 2 is eliminated, feature
It is, by calculating three frequency division, two divided-frequency and frequency tripling harmonic wave included in voltage transformer open-triangular winding voltage in real time
Component and power frequency component, when any of the above-described frequency component amplitude is more than the resonance definite value threshold of preset respective frequencies, judgement
The ferromagnetic resonance of the corresponding frequency has occurred in the voltage transformer.
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| CN201810154844.XA CN108306274B (en) | 2018-02-23 | 2018-02-23 | A kind of control method that ferromagnetic resonance for electromagnetic voltage transformer is eliminated |
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| CN201810154844.XA CN108306274B (en) | 2018-02-23 | 2018-02-23 | A kind of control method that ferromagnetic resonance for electromagnetic voltage transformer is eliminated |
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| CN108306274B CN108306274B (en) | 2019-04-09 |
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Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2293401A1 (en) * | 2009-09-07 | 2011-03-09 | ABB Research Ltd. | Protective system for voltage transformers |
| JP2013038829A (en) * | 2011-08-03 | 2013-02-21 | Nissin Electric Co Ltd | Instrument transformer and iron resonance suppression circuit |
| CN103066579A (en) * | 2012-12-24 | 2013-04-24 | 上海合凯电力保护设备有限公司 | Grid fault measuring and control device |
| CN202997549U (en) * | 2012-11-27 | 2013-06-12 | 国家电网公司 | State monitoring and resonance elimination system for intelligent power grid |
| CN203312784U (en) * | 2012-12-10 | 2013-11-27 | 江西赣东北供电公司 | 10kV voltage transformer resonance eliminating device |
| JP2014017938A (en) * | 2012-07-06 | 2014-01-30 | Mitsubishi Electric Corp | Ferro-resonance arrester and power substation using the same |
| CN103997029A (en) * | 2014-06-10 | 2014-08-20 | 重庆大学 | Ferromagnetic resonance overvoltage adaptive control system and method |
| CN204271630U (en) * | 2014-10-31 | 2015-04-15 | 国家电网公司 | Power distribution network PT Intelligent resonance suppression device |
| CN106328361A (en) * | 2016-08-30 | 2017-01-11 | 合肥智博电气有限公司 | Resonation elimination mechanism used in arc-resonation elimination device |
-
2018
- 2018-02-23 CN CN201810154844.XA patent/CN108306274B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2293401A1 (en) * | 2009-09-07 | 2011-03-09 | ABB Research Ltd. | Protective system for voltage transformers |
| JP2013038829A (en) * | 2011-08-03 | 2013-02-21 | Nissin Electric Co Ltd | Instrument transformer and iron resonance suppression circuit |
| JP2014017938A (en) * | 2012-07-06 | 2014-01-30 | Mitsubishi Electric Corp | Ferro-resonance arrester and power substation using the same |
| CN202997549U (en) * | 2012-11-27 | 2013-06-12 | 国家电网公司 | State monitoring and resonance elimination system for intelligent power grid |
| CN203312784U (en) * | 2012-12-10 | 2013-11-27 | 江西赣东北供电公司 | 10kV voltage transformer resonance eliminating device |
| CN103066579A (en) * | 2012-12-24 | 2013-04-24 | 上海合凯电力保护设备有限公司 | Grid fault measuring and control device |
| CN103997029A (en) * | 2014-06-10 | 2014-08-20 | 重庆大学 | Ferromagnetic resonance overvoltage adaptive control system and method |
| CN204271630U (en) * | 2014-10-31 | 2015-04-15 | 国家电网公司 | Power distribution network PT Intelligent resonance suppression device |
| CN106328361A (en) * | 2016-08-30 | 2017-01-11 | 合肥智博电气有限公司 | Resonation elimination mechanism used in arc-resonation elimination device |
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