CN106018991A - Power distribution network ferroresonance and single phase earth fault calculating analysis method and device - Google Patents

Power distribution network ferroresonance and single phase earth fault calculating analysis method and device Download PDF

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Publication number
CN106018991A
CN106018991A CN201610237173.4A CN201610237173A CN106018991A CN 106018991 A CN106018991 A CN 106018991A CN 201610237173 A CN201610237173 A CN 201610237173A CN 106018991 A CN106018991 A CN 106018991A
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CN
China
Prior art keywords
voltage
frequency
phase
earth fault
resonance
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CN201610237173.4A
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Chinese (zh)
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李勇
王爱军
赵勇
陈亚东
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State Grid Corp of China SGCC
State Grid Jiangsu Electric Power Co Ltd
Yancheng Power Supply Co of State Grid Jiangsu Electric Power Co Ltd
Original Assignee
State Grid Corp of China SGCC
State Grid Jiangsu Electric Power Co Ltd
Yancheng Power Supply Co of State Grid Jiangsu Electric Power Co Ltd
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Application filed by State Grid Corp of China SGCC, State Grid Jiangsu Electric Power Co Ltd, Yancheng Power Supply Co of State Grid Jiangsu Electric Power Co Ltd filed Critical State Grid Corp of China SGCC
Priority to CN201610237173.4A priority Critical patent/CN106018991A/en
Publication of CN106018991A publication Critical patent/CN106018991A/en
Pending legal-status Critical Current

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections

Abstract

The invention discloses a power distribution network ferroresonance and single phase earth fault calculating analysis method and device. The device comprises three signal processing branches (respectively a collection ABC three phase voltage branch, a collection PT opening delta frequency branch and a collection PT opening delta voltage branch), an analog-to-digital conversion module, a phase difference measurement module, a zero-crossing comparator module, a central processor module and a current constant current source module. The device can accurately distinguish frequency demultiplication resonance, high frequency resonance, fundamental frequency resonance and single phase earth faults, send different instructions to a terminal according to fault types, determine frequency demultiplication resonance and high frequency resonance according to the combination of voltage and frequency, and obtain more accurate results.

Description

A kind of power distribution network ferromagnetic resonance and singlephase earth fault calculation and analysis methods and device
Technical field
The invention belongs to power distribution network and control resist technology field, be specifically related to a kind of power distribution network ferromagnetic resonance and singlephase earth fault meter Calculation and Analysis method and device.
Background technology
In power distribution network, system neutral is usually isolated neutral system, is connected to the voltage for measuring and monitor on system busbar Transformer (PT), when voltage transformer occurs saturated, inductance is no longer constant, can become along with electric current or the change of magnetic flux Change, and automatically disappear at bus-tie circuit breaker closing operation, the single-phase arc grounding of circuit between the direct-to-ground capacitance of three-phase conducting wire, system is born Produce ferromagnetic resonance phenomenon during lotus acute variation, system overvoltage and PT overcurrent can be caused, make PT fuse failure, even burn Ruin PT.The saturated ferromagnetic resonance caused of electromagnetic potential transformer includes: fundamental resonance, high-frequency resonant, Subharmonic Resonance.Its Middle fundamental resonance there will be three-phase voltage one phase and reduces, the phenomenon of biphase rising.This is much like with singlephase earth fault, but actual On there is not the phenomenon of ground connection, the Xuhanting oral solution so fundamental resonance is otherwise known as.
Existing ferromagnetic resonance and restraining device and single-phase earth fault line selection device are all by detecting the zero of PT open-delta Sequence voltage is operated, but fundamental resonance and the phenomenon of singlephase earth fault very similar, may result in ferromagnetic resonance and press down Device processed or one-phase grounding wire-selective device misoperation, cause the accident.Additionally, existing device can not accurately distinguish fundamental resonance, High-frequency resonant, Subharmonic Resonance and singlephase earth fault, even can cause erroneous judgement, is unfavorable for taking system suitably to suppress to arrange Execute and the process of repair and maintenance personnel.Therefore it is necessary to a kind of power distribution network ferromagnetic resonance of research and development and singlephase earth fault computational analysis side Method and device, it is possible to distinguish fundamental resonance, high-frequency resonant, Subharmonic Resonance and singlephase earth fault accurately, in order to accordingly Protection device action.
Summary of the invention
For the problems referred to above, the present invention proposes a kind of power distribution network ferromagnetic resonance and singlephase earth fault calculation and analysis methods and device, Fundamental resonance, high-frequency resonant, Subharmonic Resonance and singlephase earth fault can be distinguished accurately.Difference is sent according to fault type Action command, and will determine that the terminal that result transmits preserves.
The present invention solves its problem and realizes the most by the following technical solutions:
A kind of power distribution network ferromagnetic resonance and singlephase earth fault calculation and analysis methods and device, including three road signal processing branch roads, point Not for gather ABC three-phase voltage branch road, gather PT open delta frequency branch road and gather PT open delta voltage branch road, mould Number conversion module, phase difference measurement module, zero-crossing comparator module, CPU module, electric current constant-current source module.
Described collection ABC three-phase voltage branch road includes a miniature transformer 1, a voltage follower, a low pass filter 1;Institute Stating miniature transformer 1 front end and connect PT secondary side, rear end connects described voltage follower, and described voltage follower is connected to institute Stating low pass filter 1, described low pass filter 1 connects described analog-to-digital conversion module;Described miniature transformer 1 is by PT bis-times The three-phase voltage of side be depressurized to A/D converter working range, described voltage follower plays the effect of impedance transformation, described Low pass filter 1 filters the interference of the high-frequency signal in voltage signal.
Described analog-to-digital conversion module is connected to CPU, uses the modulus conversion chip of the Approach by inchmeal of 4 Channel 12-Bits, The three-phase voltage of PT secondary side is converted to digital signal process for central processing module.
Described signals collecting PT open delta voltage one band filter, band filter input is connected to the end of PT secondary side End, band filter outfan is connected to described phase difference measurement module, and described band filter filters non-described electric current constant current mould The voltage feedback signal of the fixed frequency that the current signal of block produces.
Described phase difference measurement module is connected to CPU, using the current waveform of electric current constant-current source as reference channel, with Its feedback voltage waveform produced is TCH test channel, obtains time interval t, by central processing unit with direct-reacting digital phasometer method It is scaled phase contrast.
Described collection PT open delta frequency branch road includes a miniature transformer 2, low pass filter 2, described miniature transformer 2 Input is connected to PT open-delta, and outfan is connected to described low pass filter 2 input, described low pass filter 2 Outfan is connected to described zero-crossing comparator module.Described miniature transformer 2 is by PT open-delta opening voltage drop as little as institute Stating the working range of zero-crossing comparator, described low pass filter filters high-frequency signal interference.
Described zero-crossing comparator is connected to central processing module, and the voltage-frequency signal of PT open-delta is formed pulse, in Centre processing module obtains frequency values by step-by-step counting.
A kind of power distribution network ferromagnetic resonance judgement flow process concrete with the central processing module of singlephase earth fault computational analysis device is:
First, judge according to A, B, C three-phase voltage collected and PT open-delta electric voltage frequency:
If three-phase voltage all raises and electric voltage frequency is less than work frequency, then it is judged as Subharmonic Resonance;
If three-phase voltage all raises and electric voltage frequency is higher than work frequency, then it is judged as high-frequency resonant;
If a phase voltage reduces, two phase voltages raise and frequency is work frequency, then judge fundamental resonance or single-phase earthing event Barrier;
Secondly, if judging fundamental resonance or singlephase earth fault, continuous current source is started, by continuous current source to PT It is higher and be not the fixed frequency electric current of integral multiple of work frequency that open-triangular winding is passed through frequency, measure now open delta around The voltage of group, obtains the voltage of fixed frequency after filtering.
Simplifying circuit model, as shown in Figure 4, ignore the relevant resistance value of circuit, n1, n2 are PT high-low pressure umber of turn, The feedback voltage obtained after injecting fixed frequency electric current with the relation of electric current is,
During fundamental frequency:
During single-phase earthing:
The phase value of the fixed current being passed through is set to 0, obtains the argument θ of voltage:
During fundamental frequency:
During single-phase earthing:
The phase difference θ of the voltage obtained according to central processing unit and electric current, and comparing with 90 ° of phase angles, obtain voltage with Current phase angle changing value ε=90 °-θ, in view of the impact of synthetic error, sets a threshold value, show that criterion is as follows:
If phase angle change value is more than threshold value, it is determined that for singlephase earth fault;
If phase angle change value is less than threshold value and θ > 0, it is determined that for singlephase earth fault.
If phase angle change value is less than threshold value and θ < 0, it is determined that for fundamental resonance fault.
Power distribution network ferromagnetic resonance of the present invention with the advantage of singlephase earth fault calculation and analysis methods and device is: can distinguish accurately Go out Subharmonic Resonance, high-frequency resonant, fundamental resonance and singlephase earth fault, and according to fault type transmission different instruction to terminal, According to instruction selective resonance suppression branch road or route selection branch road;Judge Subharmonic Resonance and high-frequency resonant with voltage and frequency simultaneously, permissible Obtain the most accurate result;Different from the earth impedance of fundamental resonance according to single-phase earthing, it is passed through the voltage of electric current generation not With judging single-phase earthing and fundamental resonance, it is judged that more accurate, and the most practical.
Accompanying drawing explanation
In order to more clearly describe the technical scheme of the embodiment of the present invention, give the accompanying drawing introduced needed for the present invention.
Fig. 1 is the structural representation of the present invention;
Fig. 2 be phase difference measurement module realize schematic diagram;
Fig. 3 is injection current circuit diagram;
Fig. 4 is circuit equivalent figure;
Fig. 5 is the waveform of constant current;
Fig. 6 is to be passed through the voltage waveform that fixed current obtains during fundamental resonance;
Fig. 7 is to be passed through, during single-phase earthing (through transition resistance eutral grounding), the voltage waveform that fixed current obtains;
Fig. 8 is to be passed through, during single-phase earthing (metallic earthing), the voltage waveform that fixed current obtains;
Fig. 9 is workflow diagram of the present invention;
Specific implementation
Below in conjunction with the accompanying drawings embodiments of the invention are explained in detail.
The present invention a kind of power distribution network ferromagnetic resonance is with the advantage of singlephase earth fault calculation and analysis methods and device: can be accurate Distinguish Subharmonic Resonance, high-frequency resonant, fundamental resonance and singlephase earth fault, and according to fault type send different instruction to Terminal;Combine with voltage and frequency simultaneously and judge Subharmonic Resonance and high-frequency resonant, it is possible to obtain the most accurate result
As it is shown in figure 1, a kind of power distribution network ferromagnetic resonance and singlephase earth fault computational analysis device, prop up including three road signal processing Road, is respectively and gathers ABC three-phase voltage branch road, gathers PT open delta frequency branch road and collection PT open delta voltage props up Road, analog-to-digital conversion module, phase difference measurement module, zero-crossing comparator module, CPU module, electric current constant-current source module.
Gather ABC three-phase voltage branch road and include a miniature transformer 1, a voltage follower, a low pass filter 1;Small-sized change Depressor 1 front end connects PT secondary side, and rear end connects described voltage follower, and miniature transformer is by A, B, C of PT secondary side Three-phase voltage is depressurized to be available for-5~+5V voltages of AD conversion chip sampling, and voltage follower is connected to described low pass filter 1, low pass filter 1 connects described a/d converter, and voltage follower plays the effect of impedance transformation, reduces AD conversion chip The input impedance impact on signal, described low pass filter filters the interference of the high-frequency signal in voltage signal, the embodiment of the present invention By the frequency target signal filter higher than 500HZ.
Analog-to-digital conversion module is connected to CPU, and the embodiment of the present invention uses ADS7824P analog-to-digital conversion chip, by PT The three-phase voltage of secondary side is converted to digital signal and processes for central processing module.
Gather PT open delta voltage branch road include a band filter, band filter input be connected to PT open delta around Group, band filter outfan is connected to phase difference measurement module, after fixed frequency electric current will be passed through, PT secondary side feedback Voltage signal passes through band filter, filters power-frequency voltage signal, and the band filter of embodiments of the invention allows the frequency passed through Rate scope is 800~1200HZ.
As in figure 2 it is shown, phase difference measurement module is connected to CPU, using the current waveform of electric current constant-current source as reference Passage, with the waveform of its feedback voltage produced as TCH test channel, sinusoidal signal is become point by pulse shaping circuit by two signals Pulse, controls flip and flop generator, and thus output width is the signal strobe of Δ T, makes time lock open, clock oscillator Producing frequency is the calibration pulse of 50kHZ, is connected to central processing unit by time gate, has central processing unit to be scaled phase Potential difference.
Gathering PT open delta frequency branch road and include a miniature transformer 2, low pass filter 2, miniature transformer 2 input is even Being connected to PT open-delta, outfan is connected to described low pass filter 2 input, and low pass filter 2 outfan is connected to Described zero-crossing comparator module.Open-delta voltage signal is reduced to the zero-crossing comparator of the embodiment of the present invention by miniature transformer The operating voltage range of LM339, takes-10~+10V here, and low pass filter 2 filters the dry of the high-frequency signal in voltage signal Disturbing, frequency is higher than the target signal filter of 500HZ by the embodiment of the present invention.
Zero-crossing comparator is connected to central processing module, and embodiments of the invention use LM339 chip, by PT open-delta Voltage-frequency signal formed pulse, central processing module obtains frequency values by step-by-step counting.
As described in Figure 3, continuous current source, by central processing unit control, by being passed through fixing electricity to PT open-triangular winding Stream.It is 125Hz that embodiments of the invention produce frequency, and amplitude 10A, initial phase angle is the constant current of 0.
As it is shown in figure 5, a kind of power distribution network ferromagnetic resonance is concrete with the central processing module of singlephase earth fault computational analysis device Judge that flow process is:
First, judge according to A, B, C three-phase voltage collected and PT open-delta electric voltage frequency:
If three-phase voltage all raises and electric voltage frequency less than work frequency, then be judged as occur Subharmonic Resonance;
If three-phase voltage all raises and electric voltage frequency higher than work frequency, then be judged as occur high-frequency resonant;
If a phase voltage reduces, two phase voltages raise and the major part of frequency is work frequency, then judge to occur fundamental resonance or Singlephase earth fault;
As shown in Figure 4, have ignored resistance value R of circuit, n1, n2 are PT high-low pressure umber of turn, inject fixed frequency electricity The feedback voltage obtained after stream with the relation of electric current is,
During fundamental frequency:
During single-phase earthing:
The phase value of the fixed current being passed through is set to 0, obtains the argument θ of voltage:
During fundamental frequency:
During single-phase earthing:
The voltage obtained according to central processing unit and the phase contrast of electric current, and compare with 90 ° of phase angles, obtain voltage and electricity Stream phase angle change value ε=90 °-θ, in view of the impact of synthetic error, sets a threshold value, and the present invention is set as 2 °, draws and sentence According to as follows:
If during phase angle change value ε >=2 °, it is determined that for singlephase earth fault;
If during phase angle change value ε < 2 ° and θ > 0, it is determined that for singlephase earth fault.
If during phase angle change value ε < 2 ° and θ < 0, it is determined that for fundamental resonance fault.
In order to allow general technical staff be better understood from the present invention, distinguishing below in conjunction with describing the present invention in detail with concrete example in real time The reasonability of measure of the present invention is taked: in the simulink of MATLAB, build fundamental frequency when other singlephase earth fault and fundamental resonance The phantom of resonance, for simplified model, ignores line resistance, and the direct-to-ground capacitance of three-phase line is 6 × 10-9F, model PT is with JDZX16-10RG type voltage transformer as foundation, and the excitation reactance under the conditions of its on-Line Voltage is 1.2319M Ω, root Theoretical according to H A Peterson, it is computed understanding, circuit meets the condition that fundamental resonance occurs;There is single-phase earthing in model Fault recovers the most rapidly this situation as the condition triggering fundamental resonance.By continuous current source to the open delta of PT It is 1A that shape is passed through amplitude, and frequency is 125Hz, and initial phase angle is the alternating current of 0, measures the voltage of a PT secondary side wherein phase, For convenience, reducing interference, the voltage of the voltage source of model is set to 0, the waveform of electric current is as shown in Figure 5.Carry out base successively Frequently resonance, A phase, through transition resistance eutral grounding (transition resistance is 5000 Ω), in the case of A phase metallic ground three kinds, is passed through fixing Obtain the emulation of feedback voltage after electric current, obtain the simulation waveform of voltage such as Fig. 6 in the case of three kinds, 7,8.
From Fig. 5 and Fig. 6, the feedback voltage U that the electric current I of injection obtains, the phase angle of voltage U lagging current is 90 °, Can determine whether as there is fundamental resonance;
From Fig. 5 and Fig. 7, the feedback voltage U that the electric current I of injection obtains, it is computed, the phase angle of voltage U leading current Being 75.37 °, can determine whether as there is singlephase earth fault;
From Fig. 5 and Fig. 8, the feedback voltage U that the electric current I of injection obtains, the phase angle of voltage U leading current is 90 °, Can determine whether as there is singlephase earth fault.

Claims (5)

1. a power distribution network ferromagnetic resonance and singlephase earth fault calculation and analysis methods and device, it is characterised in that include three road letters Number process branch road, is respectively and gathers ABC three-phase voltage branch road, gathers PT open delta frequency branch road and gathers PT opening three Angle voltage branch road, analog-to-digital conversion module, phase difference measurement module, zero-crossing comparator module, CPU module, electric current is permanent Stream source module.
A kind of power distribution network ferromagnetic resonance the most according to claim 1 and singlephase earth fault calculation and analysis methods and device, It is characterized in that, described collection ABC three-phase voltage branch road includes a miniature transformer 1, a voltage follower, a low-pass filtering Device 1.
A kind of power distribution network ferromagnetic resonance the most according to claim 1 and singlephase earth fault calculation and analysis methods and device, It is characterized in that, described collection PT open delta voltage branch road includes a band filter, and described band filter is used for filtering The voltage feedback signal of the fixed frequency that the current signal of non-described electric current constant-current source module produces.
A kind of power distribution network ferromagnetic resonance the most according to claim 1 and singlephase earth fault calculation and analysis methods and device, It is characterized in that, gather PT open delta frequency branch road and include a miniature transformer 2, low pass filter 2.
A kind of power distribution network ferromagnetic resonance the most according to claim 1 and singlephase earth fault calculation and analysis methods and device, It is characterized in that,
Central processing module, for singlephase earth fault and fundamental resonance, is passed through to PT open-triangular winding by continuous current source Frequency is higher and be not the fixed frequency electric current of integral multiple of fundamental frequency, measures the feedback voltage of now PT open-triangular winding U, obtains the voltage of fixed frequency after filtering, central processing unit judges according to the phase contrast of voltage with electric current, according to central authorities The voltage that processor obtains and the phase difference θ of electric current, and compare with 90 ° of phase angles, obtain changing value ε=90 °-θ, it is contemplated that The impact of synthetic error, sets a threshold value, show that criterion is as follows:
If phase angle change value ε is more than threshold value, it is determined that for singlephase earth fault;
If phase angle change value ε is less than threshold value and θ > 0, it is determined that for singlephase earth fault;
If phase angle change value ε is less than threshold value and θ < 0, it is determined that for fundamental resonance fault.
CN201610237173.4A 2016-04-15 2016-04-15 Power distribution network ferroresonance and single phase earth fault calculating analysis method and device Pending CN106018991A (en)

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CN108008336A (en) * 2017-12-01 2018-05-08 中国电力科学研究院有限公司 A kind of device and method for calculating capacitance type potential transformer ferromagnetic resonance frequency
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Application publication date: 20161012