CN116683401B - Resonance overvoltage protection method and system for electronic voltage transformer - Google Patents
Resonance overvoltage protection method and system for electronic voltage transformer Download PDFInfo
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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
- H02H7/05—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 for capacitive voltage transformers, e.g. against resonant conditions
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/36—Overload-protection arrangements or circuits for electric measuring instruments
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/30—Circuit design
- G06F30/36—Circuit design at the analogue level
- G06F30/367—Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods
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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
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Abstract
The invention discloses a resonance overvoltage protection method and system for an electronic voltage transformer, and belongs to the technical field of overvoltage protection of electronic voltage transformers. The method comprises the following steps: collecting primary voltage waveforms at the voltage transformer; obtaining a device transfer function according to the topology of the electronic voltage transformer; judging a regulation and control mode; if the amplitude suppression mode is adopted, calculating the required resistance according to a device parameter optimization strategy; if the resonance suppression mode is adopted, calculating the required inductance according to a device parameter optimization strategy; the adjustable resistor or the adjustable inductor is adjusted to corresponding gears according to the demodulation control signals, so that the resonance overvoltage self-adaptive suppression effect is realized, and the device is protected. According to the invention, through changing the natural frequency of the electronic voltage transformer, the phenomenon that interference signals resonate on a secondary circuit of the electronic voltage transformer to generate overvoltage is avoided, so that the stable operation of equipment is ensured.
Description
Technical Field
The invention belongs to the technical field of overvoltage protection of electronic voltage transformers, and particularly relates to a resonance overvoltage protection method and system for an electronic voltage transformer.
Background
The gas-insulated switchgear tightly combines the primary and secondary devices such as the high-voltage conductor, the isolating switch and the mutual inductor, the integrated structure shortens the distance between elements in the gas-insulated switchgear, is beneficial to miniaturization of a transformer substation, and makes the mutual inductor face a harsher electromagnetic environment.
The electronic voltage transformer uses a high-voltage conductor as a part of a capacitive voltage divider thereof, and the connection mode causes strong electromagnetic interference on the electronic voltage transformer. Even if the existing protection method is adopted (such as reducing the amplitude of disturbance voltage, designing a filter, improving the shielding effectiveness of equipment, and the like), the electronic voltage transformer still frequently fails.
The existing protection method is mainly focused on the suppression of the amplitude of the harassment source, and the research on whether overvoltage can still be generated or amplified after the suppression is less. For harassment sources it has a very broad frequency spectrum (direct current to hundreds of megahertz) and a high frequency principal component with a high amplitude. For an electronic voltage transformer, it is an electro-physical system with a natural frequency. When the frequency of the disturbance source is consistent with the natural frequency of the electronic voltage transformer, the electronic voltage transformer can resonate, and the disturbance source component in the frequency band can enhance the formation of overvoltage and influence the device.
Disclosure of Invention
Aiming at the defects and improvement demands of the prior art, the invention provides a resonance overvoltage protection method and system for an electronic voltage transformer, and aims to solve the technical problem that resonance overvoltage is generated when the natural frequency of the electronic voltage transformer is overlapped with the frequency of a high-frequency main component of a disturbance source to cause the fault of the electronic voltage transformer.
To achieve the above object, in a first aspect, the present invention provides a resonance overvoltage protection method for an electronic voltage transformer, including the steps of:
transfer function of voltage transformerk(f) A frequency corresponding to a maximum point in the target frequency band is used as a natural frequencyf n The transfer functionk(f) Characterization of electricityThe relation between the output gain and the frequency of a low-voltage arm of the voltage transformer;
collecting primary voltage waveforms at the position of a voltage transformer, obtaining the amplitude of each frequency component in a target frequency band through time-frequency transformation to construct an amplitude data set, and taking the frequency corresponding to the maximum amplitude in the target frequency band as the frequency of the high-frequency main componentf h ；
For the amplitude dataset, if the amplitude threshold is exceeded in the resonance risk bandU C According to the ratio of the number of data points in the resonance risk frequency band to the total number of data points exceeding the proportional thresholdk w Transfer functionk(f) The calculation satisfiesk(f n )<k w Andk(f h )<k w The required resistance value of the high-voltage arm is regulated, and an adjustable resistor connected into the high-voltage arm of the voltage transformer is regulated, so that the high-voltage arm presents the required resistance value; otherwise, no inhibition measures are taken;
the product of the output gain of the low-voltage arm of the voltage transformer corresponding to all frequency points in the resonance risk frequency band frequency and the primary voltage component is smaller than the tolerance voltage limit value of the low-voltage arm of the voltage transformeru w ，k w Withstand voltage limit for low voltage armu w Maximum value of the ratio to the primary voltage component in the resonance risk band frequency.
Further, after calculating the required high voltage arm resistance value, before adjusting the adjustable resistor in the high voltage arm of the access voltage transformer, the method further comprises:
judging the influence of the required resistance value of the high-voltage arm on the change of the power frequency voltage dividing ratio, and if the resistance value is within the allowable range, adjusting an adjustable resistor connected into the high-voltage arm of the voltage transformer; otherwise, the adjustable resistor connected into the high-voltage arm of the voltage transformer is not adjusted, and according to the transfer functionk(f) Calculation off n ' <f risk_a The required inductance value of the high-voltage arm is regulated, an adjustable inductor connected into the high-voltage arm of the voltage transformer is regulated,the high-voltage arm is enabled to present a required inductance value;
wherein ,f n ' in order to make the natural frequency after the suppression measure,f risk_a is the lower frequency limit of the resonance risk band.
Further, the range is within the allowable range, specifically:
influence of variationNot greater than a preset threshold;
wherein ,k ' (50) and k(50) And the output gain of the low-voltage arm of the voltage transformer under the power frequency after the inhibition measures are carried out and when the inhibition measures are not carried out respectively.
Further, the range of the resonance risk frequency band is determined as follows:
acquiring natural frequency according to the amplitude data setf n And a high frequency principal component frequencyf h Corresponding amplitude componentu nmax Andu hmax ；
will beu w Divided by respectivelyu nmax Andu hmax taking the smaller value as the output gain threshold valuek w ；
Solving the equationk(f)=k w Lower frequency limit of resonance risk band with least solutionf risk_a By maximum solution andf h the larger of the two is the upper frequency limit of the resonance risk bandf risk_b Defining resonance risk bandsf risk 。
Further, the amplitude data set includes a current amplitude data set and a historical amplitude data set;
the amplitude threshold value is exceeded in the resonance risk frequency band for the amplitude data setU C The ratio of the number of data points to the number of all data points in the resonance risk frequency band exceeds a proportional threshold, comprising:
for the followingThe current amplitude data set and the historical amplitude data set, if one of the current amplitude data set and the historical amplitude data set meets the following conditions: exceeding amplitude threshold in resonance risk bandU C The duty cycle of all data points within the resonance risk band exceeds a proportional threshold.
Further, the amplitude threshold valueU C Is that，U W Is the voltage amplitude of the power frequency component,Aa constant of 1 or more.
In a second aspect, the present invention provides another method for protecting an electronic voltage transformer from resonance overvoltage, comprising the steps of:
transfer function of voltage transformerk(f) A frequency corresponding to a maximum point in the target frequency band is used as a natural frequencyf n The transfer functionk(f) Representing the relation between the output gain and the frequency of a low-voltage arm of the voltage transformer;
acquiring primary voltage waveforms at the position of a voltage transformer, and acquiring the amplitude of each frequency component in a target frequency band through time-frequency transformation to construct an amplitude data set;
for the amplitude dataset, if the amplitude threshold is exceeded in the resonance risk bandU C The ratio of the data points in the resonance risk frequency band exceeds a proportional threshold, according to the transfer functionk(f) Calculation off n ' <f risk_a The required inductance value of the high-voltage arm is regulated, and an adjustable inductor connected into the high-voltage arm of the voltage transformer is regulated, so that the high-voltage arm presents the required inductance value; otherwise, no inhibition measures are taken;
wherein ,f n ' in order to make the natural frequency after the suppression measure,f risk_a for the lower frequency limit of the resonance risk frequency band, the product of the output gain of the low-voltage arm of the voltage transformer corresponding to all frequency points in the resonance risk frequency band and the primary voltage component is smaller thanWithstand voltage limit value of low-voltage arm of voltage transformeru w 。
Further, the range of the resonance risk frequency band is determined as follows:
the range of the resonance risk band is determined as follows:
acquiring natural frequency according to the amplitude data setf n And a high frequency principal component frequencyf h Corresponding amplitude componentu nmax Andu hmax ；
will beu w Divided by respectivelyu nmax Andu hmax taking the smaller value as the output gain threshold valuek w ；
Solving the equationk(f)=k w Lower frequency limit of resonance risk band with least solutionf risk_a By maximum solution andf h the larger of the two is the upper frequency limit of the resonance risk bandf risk_b Defining resonance risk bandsf risk 。
Further, the amplitude data set includes a current amplitude data set and a historical amplitude data set;
the amplitude threshold value is exceeded in the resonance risk frequency band for the amplitude data setU C The ratio of the number of data points to the number of all data points in the resonance risk frequency band exceeds a proportional threshold, comprising:
for the current amplitude dataset and the historical amplitude dataset, if one of them is satisfied: exceeding amplitude threshold in resonance risk bandU C The duty cycle of all data points within the resonance risk band exceeds a proportional threshold.
In a third aspect, the present invention provides a resonant overvoltage protection system for an electronic voltage transformer, comprising:
a processor; and
a memory for storing executable instructions of the processor;
wherein the processor is configured to perform the resonant overvoltage protection method for an electronic voltage transformer of the first or second aspect via execution of the executable instructions.
In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be obtained:
aiming at the problem that the frequency of a disturbance source is consistent with the natural frequency of an electronic voltage transformer, the electronic voltage transformer can resonate, and the disturbance source component of the frequency band forms overvoltage and affects devices, the invention provides a resonance overvoltage protection method and system for the electronic voltage transformer. The method comprises the steps of connecting an adjustable resistor or an adjustable inductor into a high-voltage arm loop of an electronic voltage transformer, using numerical simulation to equivalent an electronic voltage transformer model into a circuit model, obtaining the influence rule of each component on the transfer characteristic of the electronic voltage transformer through circuit theory analysis, changing the transfer characteristic of the electronic voltage transformer according to the influence rule, reducing the output gain of the electronic voltage transformer at the frequency of a high-frequency main component of a received signal or staggering the natural frequency of the electronic voltage transformer from the frequency of the high-frequency main component of the received signal, and thus reducing the amplitude of overvoltage generated by resonance on the electronic voltage transformer.
Drawings
Fig. 1 is a schematic structural diagram of a resonant overvoltage protection device for an electronic voltage transformer according to the present invention.
Fig. 2 is a schematic flow chart of a resonance overvoltage protection method for an electronic voltage transformer.
Fig. 3 is a schematic block diagram of an electronic voltage transformer in an embodiment of the invention.
Fig. 4 is a transfer characteristic of an electronic voltage transformer according to an embodiment of the present invention.
Fig. 5 is a waveform diagram of a primary signal in an embodiment of the present invention.
Fig. 6 is a partial enlarged view of the circled portion in fig. 5.
Fig. 7 is a spectrum diagram of the circled portion in fig. 5.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
Referring to fig. 1, the present invention provides a resonance overvoltage protection device for an electronic voltage transformer, comprising: 1-SF6 gas; 2-polar plates; 3-gas isolating switch pipe casing; 4-shielding a box body; 5-a data processing device; 6-an optical fiber communication device; 7-a low-voltage arm circuit; 8-an adjustable resistor and an adjustable inductor; 9-insulating material; 10-high voltage bus.
The embodiment constructs an electronic voltage transformer model for implementing analysis based on the structure of the electronic voltage transformer.
Meanwhile, considering that the electronic voltage transformer and the connection part thereof are not flat in practice, the embodiment ignores the connection and the bulge of the equipment shell and equivalent the polar plate 2 to a plane; the gas isolating switch pipeline shell 3 is equivalent to a hollow cylindrical pipeline; the high-voltage busbar 10 is equivalent to a hollow cylinder.
Based on the hardware configured as above, the invention provides a resonance overvoltage protection method for an electronic voltage transformer, which has the following basic ideas: aiming at two electromagnetic transient impacts of global overvoltage and resonance overvoltage, based on current and historical monitoring data of bus voltage, according to the power frequency rated transformation ratio and natural frequency of a target voltage transformer, judging a suppression mode to be adopted, calculating a specific value of a resistance (inductance) device, and further adjusting the variable resistance (inductance) device to effectively suppress transient overvoltage.
As shown in fig. 2, the present embodiment provides a resonance overvoltage protection method for an electronic voltage transformer, which includes steps S100 to S500.
S100, mutually connecting voltagesTransfer function of sensork(f) A frequency corresponding to a maximum point in the target frequency band is used as a natural frequencyf n The transfer functionk(f) And the relation between the output gain and the frequency of the low-voltage arm of the voltage transformer is represented.
In this embodiment, the natural frequency is obtained by deriving the transfer function and the electronic device characteristics according to the topology of the voltage transformerf n Withstand voltage limit value of low-voltage arm of voltage transformeru w Setting the target frequency band asf n 10 to (10×)f n ) A frequency range.
Wherein the transfer functionk(f) The method is a formula obtained by combining the principle structure of equipment and equivalent calculation of device parameters. Transfer functionk(f) The empirical formula is as follows:
i.e. in terms of the ratio of the impedance of the low-voltage arm loop of the electronic voltage transformer to the impedance of the electronic voltage transformer.
The schematic structure diagram of the electronic voltage transformer is shown in fig. 3, and the transfer function is based on the impedance Z of the low-voltage arm loop of the electronic voltage transformer after the structural model in fig. 1 is converted into the circuit model by the circuit theory L Impedance Z with the electronic voltage transformer D Ratios are listed; z is Z c1 Is a high-voltage arm capacitorC 1 Impedance, Z c2 Is a low-voltage arm capacitorC 2 Impedance of (c); z is Z a Refers to the sum of the impedance of other devices in the low voltage arm, such as stray resistance and stray inductance in the low voltage arm, in addition to the low voltage arm capacitance; z is Z b Refers to the sum of the impedances of other devices within the device than the high voltage arm capacitance, such as stray resistance in the high voltage arm, stray inductance, low voltage arm impedance, stray parameters on the ground loop (resistance, inductance, etc.).
In the view of figure 3 of the drawings,C 1 is an electrode plate and a high-voltage busbar in a GIS pipelineA high voltage arm capacitor formed by wire coupling,C 2 is a patch capacitor on a low-voltage arm PCB,C 3 is the coupling capacitance between the electrode plate and the GIS shell,L 1 、R 1 l is parasitic inductance and equivalent resistance on the connecting line between the electrode plate and the PCB C2 、R C2 L is parasitic inductance and equivalent resistance on PCB g1 、R g1 L is parasitic inductance and equivalent resistance of connecting line between PCB and GIS shell g2 、R g2 R is parasitic inductance and equivalent resistance of a connecting line between the GIS shell and the ground p 、L rp 、R rp L is the parasitic inductance and equivalent resistance of the surge suppression resistor and the branch thereof t 、R t Parasitic inductance and equivalent resistance of transient voltage suppressing diode and its branch, R f 、C f Is a low-pass filter L rf 、L cf 、R rf 、R cf C is parasitic inductance and equivalent resistance on the low-pass filter branch r 、L cr 、R cr Is the parasitic inductance and equivalent resistance on the inlet capacitance and branch of the differential operational amplifier.
Device low voltage arm withstand voltage limitu w Refers to at natural frequencyf n According to the voltage withstand value of electronic components in the secondary circuit of the electronic voltage transformer and the relation of the voltage withstand value in the circuit, the voltage withstand value is converted into a voltage value on a low-voltage arm, wherein the minimum value is the withstand voltage limit value of the low-voltage arm of the equipmentu w 。
For example, in the electronic voltage transformer shown in fig. 3, it is assumed that the resistance R at the natural frequency p 88 omega, and the withstand voltage value is 800V; resistor R rp 1 omega, and 10V; inductance L rp The impedance is 1Ω. The impedance of the right-end circuit is 10Ω, and the resistor R p 、R rp Inductance L rp The voltage division ratio of the composed protection branch circuit to the right-end circuit is 9:1. if the capacitance isC 2 The voltage of the low-voltage arm is 1000V, and the resistor R p Is 880V, resistance R rp The partial pressure of (2) is 10V, and the requirement of the voltage resistance of the device is not met; if the capacitance isC 2 The voltage of the low voltage arm is 909V, and the resistor R p Is 800V, resistor R rp The partial pressure of (2) is 9V, and meets the requirement of the voltage resistance value of the deviceu w Is 909V.
The transfer function of the electronic voltage transformer is the relation between the output gain of the low-voltage arm and the frequency, namely, wherein fIn order to be a frequency of the light,kwhen the frequency isfOutput gain of low-voltage arm of time electronic voltage transformer, corresponding to different types of electronic voltage transformerk(f) Is known to bek(f) The maximum point in the target frequency band is defined as the natural frequencyf n 。
Preferably, the transfer characteristics of the electronic voltage transformer shown in fig. 3 can be derived from the following equation:
wherein ,ZL Is the impedance of a low-voltage arm of the electronic voltage transformer, Z LRH Impedance of high-voltage arm of electronic voltage transformer, Z 1 High voltage arm capacitance impedance, Z, of electronic voltage transformer 2 The low-voltage arm impedance and the high-voltage arm impedance in the electronic voltage transformer are connected in series and then are connected in parallel with the stray capacitance impedance formed between the high-voltage arm capacitance polar plate and the pipeline shell of the electronic voltage transformer, Z LRL Is the impedance of the grounded portion of the electronic voltage transformer. The specific mathematical calculation expression is shown in table 1.
For example, when the components in the electronic voltage transformer are selected according to the values in table 2, the transfer characteristics are as shown in fig. 4, and two maximum values of the output gain exist at this time, respectivelyf 1 =14.6 MHz sumf 2 Corresponding output gain = 37.32MHzRespectively isk 1=1.49 and k 2 =1.133. For convenience of explanation, the present embodiment uses the first natural frequency pointf 1 For example, the target band is (1.46 MHz to 146 MHz) =14.6mhz.
S200, collecting primary voltage waveforms at the position of the voltage transformer, obtaining the amplitude of each frequency component in the target frequency band through time-frequency transformation to construct an amplitude data set, and taking the frequency corresponding to the maximum amplitude in the target frequency band as the frequency of the high-frequency main componentf h 。
For the current moment, acquiring a current amplitude data set according to an overvoltage waveform of the voltage transformer mounting part, and calculating the voltage amplitude of the power frequency componentU W Setting an amplitude thresholdU C Is thatPreferably, the composition of the present invention, preferably,A=1000, and determines that the frequency of the main component of the high frequency in the target frequency band isf h A resonance risk band frequency range off risk_a To the point off risk_b 。
The primary signal of the position of the electronic voltage transformer refers to a voltage signal measured at the position or adjacent position of the electronic voltage transformer. The overvoltage waveform is obtained by means of monitoring by a hand hole type high-frequency sensor head, and the hand hole type high-frequency sensor head has high-precision measurement performance on high-frequency signals and provides accurate voltage waveforms for subsequent frequency spectrum calculation.
Performing time-frequency transformation on the overvoltage waveform to obtain the amplitude of each component, and collecting the amplitude of each frequency component in the target frequency band range to construct a current amplitude data set; for each component in the target frequency band, searching the maximum amplitude, wherein the corresponding frequency is the frequency of the main component of the high frequencyf h 。
Voltage transformer corresponding to all frequency points in resonance risk frequency band frequencyThe product of the output gain of the low-voltage arm and the primary voltage component is smaller than the withstand voltage limit value of the low-voltage arm of the voltage transformeru w . Illustratively, the range of the resonance risk band is determined as follows: by calculating natural frequencies in primary signalsf n And a high frequency principal component frequencyf h Corresponding amplitude componentu nmax Andu hmax will beu w Divided by respectivelyu nmax Andu hmax taking the smaller value as the output gain threshold valuek w The method comprises the steps of carrying out a first treatment on the surface of the Solving the equationk(f)=k w Lower frequency limit of resonance risk band with least solutionf risk_a By maximum solution andf h the larger of the two is the upper frequency limit of the resonance risk bandf risk_b Defining resonance risk bandsf risk 。
For example, when the waveform of the primary signal is as shown in fig. 5, the amplitude of the power frequency component of the primary signal is 180kV, and the amplitude threshold is 180V. Selecting transient waveform, namely circled part in figure 5, and its partial enlarged view is shown in figure 6, and performing Fourier analysis to obtain frequency spectrum shown in figure 7, wherein the frequency of high-frequency principal component isf h = 12.74MHz, at which time the device transfer functionk(f) Natural frequency of the upper part isf n =14.6MHz。
In the present embodiment, it is assumed that the device low voltage arm withstand voltage limit valueu w =1 kV, then the gain threshold is outputk w 1/20.2.apprxeq.0.049.
From the calculation in S100, it is known that there are 2 frequency points satisfyingk w Requirements of =0.049, i.ef w1 =12.09MHz，f w2 =45.1MHz。
Preferably, forf w According tof h Historical distribution data of (a) and output gain thresholdk w Is selected: 1.1, to be selectedf w Should be covered withf h Is covered by the historical data distribution range; 1.2 selecting the minimum coveragef w As a starting point. 2. If there is nof w Quilt is covered withf h Is covered by the historical data distribution range of (1), then the distance is selectedf h Historical minimum nearestf w As a starting point. Assume thatf w1 And (3) withf w2 Are all covered byf h Is covered by the range of the historical data distributionf w1 For optimal selection, the resonance risk band range should be (12.09 MHz,45.1 MHz) at this time.
In addition, accidental errors are avoided when the current amplitude data are acquired, or random errors are avoided when the current amplitude data set, so that whether suppression measures are inaccurate or not is judged, and a historical amplitude data set and a historical frequency data set can be acquired, specifically:
s300, for each historical moment, acquiring a historical amplitude data set and a historical frequency data set according to the historical overvoltage waveform of the voltage transformer installation position.
For each historical moment, corresponding amplitude data sets are collected to construct a historical amplitude data set; and for each historical moment, the frequencies of the corresponding high-frequency main components are collected to construct a historical frequency data set. For example, assuming that the primary signal waveform shown in FIG. 5 is the 10 th acquisition waveform, the high-frequency main component frequency thereoff h = 12.74MHz and the amplitude is the 10 th set of data of the historical frequency dataset.
S400, if the amplitude data set exceeds the amplitude threshold value in the resonance risk frequency bandU C According to the ratio of the number of data points in the resonance risk frequency band to the total number of data points exceeding the proportional thresholdk w Transfer functionk(f) The calculation satisfiesk(f n )<k w Andk(f h )<k w The required resistance value of the high-voltage arm is regulated, and an adjustable resistor connected into the high-voltage arm of the voltage transformer is regulated, so that the high-voltage arm presents the required resistance valueA desired resistance value; otherwise, no inhibition measures are taken; the product of the output gain of the low-voltage arm of the voltage transformer corresponding to all frequency points in the resonance risk frequency band frequency and the primary voltage component is smaller than the tolerance voltage limit value of the low-voltage arm of the voltage transformeru w ，k w Withstand voltage limit for low voltage armu w Maximum value of the ratio to the primary voltage component in the resonance risk band frequency.
In this embodiment, the determination of the regulation mode is performed from three modes of amplitude suppression, resonance suppression, and non-action, and the specific value of the corresponding device is calculated. Step S400 includes sub-steps S410 to S440.
In sub-step S410, a determination is made as to whether a suppression measure needs to be activated based on the current amplitude dataset or (current amplitude dataset and historical amplitude dataset). Taking the current amplitude dataset and the historical amplitude dataset as examples:
in this embodiment, the current data size of the primary signal spectrum in the resonance risk frequency band is 1000, and if the amplitude of more than 500 data points is greater than 180V, the duty ratio isr 1 Over 50%; if the amplitude of less than 500 data points is greater than 180V, the duty cycler 1 Less than 50%.
The number of the historical data of the primary signal frequency spectrum in the resonance risk frequency band is 10 ten thousand, if the amplitude of more than 5 ten thousand data points is more than 180V, the ratio isr 2 Over 50%; if less than 5 ten thousand data points are greater than 180V, the duty cycler 2 Less than 50%.
If it isr 1 、r 2 At least one of which exceeds 50%, it is considered that a suppression measure is to be performed; if it isr 1 、r 2 No more than 50%, and no start-up inhibition is considered necessary.
In sub-step S420, amplitude suppression is preferentially initiated according tok w Transfer functionk(f) The calculation satisfiesk(f n )<k w Andk(f h )<k w Required high voltage arm resistanceValue ofR High-voltage arm And adjusting an adjustable resistor connected into a high-voltage arm of the voltage transformer to enable the high-voltage arm to present a required resistance value, so that a transfer function is at a natural frequencyf n Andf h The amplitude of the voltage transformer is not larger than the withstand voltage limit value of the low-voltage arm of the voltage transformer.
In the present embodiment of the present invention,f h =12.74MHz，f n =14.6 MHz, by calculation, the primary signal is atf h The component amplitude at isu hmax =20.2 kV at natural frequencyf n The component amplitude at isu nmax =6.1 kV. Assume thatu w =1 kV, then the gain threshold is outputk w 1/20.2.apprxeq.0.049.
According to the output gain thresholdk w The calculated transfer characteristic is smaller thank w Required thatR High-voltage arm Selecting proper device combination mode number to makef h Where the output gain is less than the output gain thresholdk w 。
In order to makek(f h ) Less than or equal to 0.049, calculate the transfer characteristics whenR High-voltage arm >At the time of 20.6Ω, the temperature of the product,k(f h ) 0.04848 is not more than and meets the requirement, and the minimum resistance value of the adjustable resistor is 20 omega.
For the selection of the combination, the following rules are followed: in a limited number of combinations, so that after the inhibition measures are takenf n Andf h Output gain atk ' (f n )、k ' (f h ) The resistor combination has a resistance value that meets the requirements without exceeding the set output gain threshold. Preferably, when one or more of the resistance values meet the requirements, the combination with the smallest resistance value is selected, thereby reducing the influence on the measurement signal.
In this embodiment, when the resistance of the adjustable resistor is 12.2Ω,f n output gain atk ' (f n ) The number of the components is 0.078,f h output gain atk ' (f h ) Is 0.049, not less thank w Conditions of (2); when the resistance of the adjustable resistor is 20Ω,k ' (f n ) The number of the steps of the method is 0.048,k ' (f h ) Is 0.035, meets the requirement of less thank w Conditions of (2); when the resistance of the adjustable resistor is 21Ω,k ' (f n ) The number of the steps of the method is 0.046,k ' (f h ) 0.034, which is less thank w Is a condition of (2). At this point the adjustable resistor should be chosen to be adjusted to 20Ω.
Further, in substep S430, the influence of the resistance value calculated in S420 on the electronic voltage transformer is determined to be reasonable, so as to determine to generate a corresponding control signal or develop a resonance suppression mode. The transfer function of the equipment under the power frequency is as follows when no inhibition measures are carried outk(50) The transfer function of the equipment under the power frequency after the inhibition measure is developed isk ' (50) Calculating the power frequency transformation ratio condition before and after the development of the inhibition measure, if the change affectsIf the amplitude suppression mode is more than 2 per mill, the amplitude suppression mode is considered to have a larger influence on the power frequency measurement performance of the electronic voltage transformer, so that the amplitude suppression mode is stopped, and the resonance suppression mode is developed; if the influence of changes is->And if the power is not more than 2 per mill, sending a control signal and forming regulation.
In this embodiment, the transfer functions of the electronic voltage transformer have magnitudes at the power frequency ofIf the power frequency amplitude after the resistor is added is +.>At this time, the influence of the change +.>At this time->The resistance value meets the requirement; if the power frequency amplitude after the resistor is added is +.>At this time, the influence of the change +.>At this time->The resistance value does not meet the requirement and the resonance suppression mode is developed.
In sub-step S440, the resonance suppression mode is specifically: according to transfer functionk(f) Calculation off n ' <f risk_a The required inductance value of the high-voltage arm is regulated, and an adjustable inductor connected into the high-voltage arm of the voltage transformer is adopted, so that the high-voltage arm presents the required inductance value, the frequency of the maximum value point of the output gain of the equipment can be shifted out of a resonance risk frequency band, and the amplitude of the transfer function in the resonance risk frequency band meets the requirement that the secondary voltage is not more than the tolerance voltage limit value of the low-voltage arm of the voltage transformer.
In order to shift the natural frequency of the device out of the resonance risk band, the device should be shiftedf n ' <12.09MHz, the transfer characteristics were calculated asL High-voltage arm >At the time of 540nH, the temperature of the sample,f n ' <12.09MHz, which meets the requirements, and the minimum inductance of the tunable inductor should be 210nH.
For the selection of the combination, the following rules are followed: in a limited number of combinations, the natural frequency after the inhibition measure is satisfiedAnd is also provided withf n ' <f risk_a New transfer functions of the device are shown inf h Original natural frequencyf n The output gain does not exceed the set output gain thresholdk w The inductance combination has an inductance value that meets the requirements.
In this embodiment, when the inductance value of the tunable inductor is a series combination of 1 μH and 5 μH, the new natural frequency isf n ' = 3.885MHz, and satisfiesAnd is also provided withf n ' <The 12.09MHz condition, where the output gains at 12.09MHz and 12.74MHz are 0.001782 and 0.001786, respectively, are less than 0.049, the tunable inductor can be tuned to 6 μH.
In a further alternative embodiment, in a sub-operation S320, after determining that a suppression measure is required, resonance suppression is directly initiated, i.e. in accordance with a transfer functionk(f) Calculation off n ' <f risk_a And the required inductance value of the high-voltage arm is regulated, and an adjustable inductor connected into the high-voltage arm of the voltage transformer is regulated, so that the high-voltage arm presents the required inductance value.
Further, after determining the required resistance value or inductance value of the high voltage arm, the method further comprises:
s500, modulating a signal to be transmitted according to a modulation and demodulation rule of a switching device; transmitting a signal to be transmitted to an optical fiber communication device through an optical fiber; the optical fiber communication device receives and demodulates the control instruction, and the adjustable resistor or the adjustable inductor is adjusted to a corresponding gear according to the demodulation control signal, so that the resonance overvoltage self-adaptive suppression effect is realized, and the device is protected.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (8)
1. The resonance overvoltage protection method for the electronic voltage transformer is characterized by comprising the following steps of:
transfer function of voltage transformerk( f ) A frequency corresponding to a maximum point in the target frequency band is used as a natural frequencyf n The transfer functionk( f ) Representing the relation between the output gain and the frequency of a low-voltage arm of the voltage transformer;
collecting primary voltage waveforms at the position of a voltage transformer, obtaining the amplitude of each frequency component in a target frequency band through time-frequency transformation to construct an amplitude data set, and taking the frequency corresponding to the maximum amplitude in the target frequency band as the frequency of the high-frequency main componentf h ；
For the amplitude dataset, if the amplitude threshold is exceeded in the resonance risk bandU C According to the ratio of the number of data points in the resonance risk frequency band to the total number of data points exceeding the proportional thresholdk w Transfer functionk( f ) The calculation satisfiesk( f n )<k w Andk( f h )<k w The required resistance value of the high-voltage arm is regulated, and an adjustable resistor connected into the high-voltage arm of the voltage transformer is regulated, so that the high-voltage arm presents the required resistance value; otherwise, no inhibition measures are taken;
wherein the range of the resonance risk frequency band is determined as follows:
acquiring natural frequency according to the amplitude data setf n And a high frequency principal component frequencyf h Corresponding amplitude componentu nmax Andu hmax ；
will beu w Divided by respectivelyu nmax Andu hmax taking the smaller value as the output gain threshold valuek w ；
Solving the equationk( f )= k w Lower frequency limit of resonance risk band with least solutionf risk_a By maximum solution andf h the larger of the two is the upper frequency limit of the resonance risk bandf risk_b Defining resonance risk bandsf risk 。
2. The resonant overvoltage protection method for an electronic voltage transformer of claim 1, wherein after calculating the required high voltage arm resistance value, before adjusting the adjustable resistor in the high voltage arm of the voltage transformer, the method further comprises:
judging the influence of the required resistance value of the high-voltage arm on the change of the power frequency voltage dividing ratio, and if the resistance value is within the allowable range, adjusting an adjustable resistor connected into the high-voltage arm of the voltage transformer; otherwise, the adjustable resistor connected into the high-voltage arm of the voltage transformer is not adjusted, and according to the transfer functionk( f ) Calculation off n ' < f risk_a The required inductance value of the high-voltage arm is regulated, and an adjustable inductor connected into the high-voltage arm of the voltage transformer is regulated, so that the high-voltage arm presents the required inductance value;
wherein ,f n ' natural frequency after the suppression measure is performed.
3. The resonance overvoltage protection method for electronic voltage transformers according to claim 2, characterized in that said range is within the allowed range, in particular:
influence of variationNot greater than a preset threshold;
wherein ,k ' (50) and k(50) And the output gain of the low-voltage arm of the voltage transformer under the power frequency after the inhibition measures are carried out and when the inhibition measures are not carried out respectively.
4. A resonant overvoltage protection method for an electronic voltage transformer according to any one of claims 1 to 3, wherein the amplitude dataset comprises a current amplitude dataset and a historical amplitude dataset;
the amplitude threshold value is exceeded in the resonance risk frequency band for the amplitude data setU C The ratio of the number of data points to the number of all data points in the resonance risk frequency band exceeds a proportional threshold, comprising:
for the current amplitude dataset and the historical amplitude dataset, if one of them is satisfied: exceeding amplitude threshold in resonance risk bandU C The duty cycle of all data points within the resonance risk band exceeds a proportional threshold.
5. A resonant overvoltage protection method for an electronic voltage transformer according to any one of claims 1 to 3, said amplitude threshold valueU C Is that，U W Is the voltage amplitude of the power frequency component,Aa constant of 1 or more.
6. The resonance overvoltage protection method for the electronic voltage transformer is characterized by comprising the following steps of:
transfer function of voltage transformerk( f ) A frequency corresponding to a maximum point in the target frequency band is used as a natural frequencyf n The transfer functionk( f ) Representing the relation between the output gain and the frequency of a low-voltage arm of the voltage transformer;
collecting primary voltage waveforms at the position of a voltage transformer, obtaining the amplitude of each frequency component in a target frequency band through time-frequency transformation to construct an amplitude data set, and taking the frequency corresponding to the maximum amplitude in the target frequency band as the frequency of the high-frequency main componentf h ；
For the amplitude dataset, if the amplitude threshold is exceeded in the resonance risk bandU C The ratio of the number of data points in the resonance risk frequency band exceeds a proportional thresholdAccording to the transfer functionk( f ) Calculation off n ' < f risk_a The required inductance value of the high-voltage arm is regulated, and an adjustable inductor connected into the high-voltage arm of the voltage transformer is regulated, so that the high-voltage arm presents the required inductance value; otherwise, no inhibition measures are taken;
wherein ,f n ' for natural frequencies after the suppression measures, the range of the resonance risk band is determined as follows:
acquiring natural frequency according to the amplitude data setf n And a high frequency principal component frequencyf h Corresponding amplitude componentu nmax Andu hmax ；
will beu w Divided by respectivelyu nmax Andu hmax taking the smaller value as the output gain threshold valuek w ；
Solving the equationk( f )= k w Lower frequency limit of resonance risk band with least solutionf risk_a By maximum solution andf h the larger of the two is the upper frequency limit of the resonance risk bandf risk_b Defining resonance risk bandsf risk 。
7. The resonant overvoltage protection method for an electronic voltage transformer of claim 6, wherein the amplitude dataset comprises a current amplitude dataset and a historical amplitude dataset;
the amplitude threshold value is exceeded in the resonance risk frequency band for the amplitude data setU C The ratio of the number of data points to the number of all data points in the resonance risk frequency band exceeds a proportional threshold, comprising:
for the current amplitude dataset and the historical amplitude dataset, if one of them is satisfied: exceeding amplitude threshold in resonance risk bandU C Data points in the resonance risk frequency bandThe duty cycle of the total number of data points exceeds the scaling threshold.
8. A resonant overvoltage protection system for an electronic voltage transformer, comprising:
a processor; and
a memory for storing executable instructions of the processor;
wherein the processor is configured to perform the resonant overvoltage protection method for an electronic voltage transformer of any one of claims 1-7 via execution of the executable instructions.
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