CN115267417B - Accurate positioning method for power transmission line faults and power transmission line traveling wave measuring device - Google Patents
Accurate positioning method for power transmission line faults and power transmission line traveling wave measuring device Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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Abstract
The invention provides a precise positioning method for a power transmission line fault and a power transmission line traveling wave measuring device; the data acquisition unit is arranged at one end of the power transmission line, which is high in voltage, and is used for acquiring fault current traveling wave signals of the power transmission line, the signal output end of the data acquisition unit is connected with the analog signal input end of the A/D converter, the digital signal output end of the A/D converter is connected with the data bus input/output end of the FIFO memory, the data output end of the FIFO memory is connected with the data input end of the DSP controller, the data output end of the DSP controller is connected with the data input end of the data processing unit, and the DSP controller reads the data in the FIFO memory and transmits the data to the data processing unit for subsequent calculation processing; the data output end of the data processing unit is used for continuous transmission through a connected Ethernet interface.
Description
Technical Field
The invention relates to the technical fields of transmission and distribution network online monitoring, fault positioning and line maintenance, in particular to a precise positioning method for a transmission line fault and a transmission line traveling wave measuring device.
Background
The power transmission and distribution line is a bridge between the power grid and the user, bears an important task of safely and reliably distributing electric energy to the user terminal, and more than 85% of the generated energy in China is transmitted to the user through the power distribution network according to statistics of the national power grid; meanwhile, the power distribution network is also a high-incidence area of the power system faults, and according to investigation, more than 90% of power failures of the power system are caused by the power distribution line faults; how to quickly, simply, conveniently, efficiently and accurately locate faults of a power transmission line is a problem to be solved urgently at present.
Disclosure of Invention
In order to solve the technical problems, the invention provides a precise positioning method for a power transmission line fault and a power transmission line traveling wave measuring device.
A transmission line traveling wave measurement apparatus, comprising: the system comprises a data acquisition unit, an A/D converter, a FIFO memory, a DSP controller and a data processing unit;
the data acquisition unit is arranged at one end, namely a current input end, of the power transmission line, with high voltage, the data acquisition unit is used for acquiring fault current traveling wave signals of the power transmission line, a signal output end of the data acquisition unit is connected with an analog signal input end of the A/D converter, a digital signal output end of the A/D converter is connected with a data bus input/output end of the FIFO memory, the A/D converter is used for transmitting converted digital signals to the FIFO memory for storage, a data output end of the FIFO memory is connected with a data input end of the DSP controller, a data output end of the DSP controller is connected with a data input end of the data processing unit, and data in the FIFO memory is read by the DSP controller and transmitted to the data processing unit in real time for subsequent calculation; the data output end of the data processing unit is used for continuous transmission through a connected Ethernet interface.
Further, the data acquisition unit comprises a Rogowski coil electronic current transformer and an integrator, wherein the Rogowski coil electronic current transformer is sleeved on the periphery of the power transmission line and is used for acquiring signals; the Rogowski coil electronic current transformer is used for collecting current signals of a power transmission line, the positive electrode and the negative electrode of an output pin of the Rogowski coil electronic current transformer are correspondingly connected with a non-inverting input end and an inverting input end of an integrator respectively, and the output end of the integrator is connected with the non-inverting input end of the integrator through a capacitor and used for feedback; an inductor is connected in series between the positive electrode of the output pin of the Rogowski coil electronic current transformer and the non-inverting input end of the integrator, and is used for inhibiting high-frequency interference; the integrator is used for converting the input acquisition signal into a fault current traveling wave signal.
Further, the power transmission line traveling wave measuring device is characterized in that the A/D converter is of the model ADS8342; the FIFO memory is of a model number of FIFO IDT72V3680; the A/D converter converts fault current travelling wave signals received by the input end into digital signals and then transmits the digital signals to the FIFO memory for storage, and the FIFO memory is also used for buffering fault signal data;
the data bus input end of the DSP controller reads in data, and then the DSP controller sends the read data into the data processing unit through the Ethernet interface of the data output end of the DSP controller, so that the data processing unit obtains fault information; the DSP controller adopts TMS320C6205 model of 32bit series in TMS320C series chip.
The invention also provides a method for accurately positioning the power transmission line fault based on the power transmission line traveling wave measurement device, which comprises the following steps:
1) A data processing unit in the travelling wave measuring device of the power transmission line reads travelling wave current data x (t), wherein the travelling wave current data is a travelling wave current value of a monitoring point in a monitoring time interval, and the travelling wave current value comprises travelling wave current in a fault state;
2) Then, the original traveling wave current data x (t) is subjected to direct current filtering by adopting an arithmetic average method, the original traveling wave current data x (t) is averaged to obtain direct current interference in the original data, and the direct current interference is recorded asFrom the original data x (t), the mean +.>Obtaining data y (t) for filtering direct current interference;
because the traveling wave current data is a high-frequency signal, the surrounding low-frequency interference signals are coupled into the traveling wave current signal in the monitoring process, so that the low-frequency interference signals in the traveling wave current data are removed, the frequency response curve of the Butterworth filter in a passband is maximally flat and has no fluctuation, and gradually drops to zero in a blocking band;
the Butterworth band-pass filter is adopted for filtering, and firstly, according to the frequency band range of the traveling wave signal and the filtering requirement, the set coefficients comprise the pass band cut-off frequency w 1 Stop band cut-off frequency w 2 Passband ripple R p And stopband attenuation R s For convenience of calculation, generally take w 1 ＝w n Sampling frequency F s =2000000 Hz, signals above 1000000Hz and 200000Hz are filtered out in view of the travelling wave signal frequency range, thus designing the passband cut-off frequency w 1 =100000 Hz, stop band cut-off frequency w 2 =200000 Hz passband ripple R p =2db, stop band attenuation R s ＝40dB；
Next, solving the analog bandpass filter index; for different cut-off frequencies w n The transfer functions of the Butterworth filters of the same order are also different, and in order to make the filter design have universality, the frequency needs to be normalized;
passband cut-off frequency normalization: w (w) p ＝1/(F s /w 1 )
Normalization of stop band cut-off frequency: w (w) s ＝2/(F s /w 2 )；
Since the butterworth filter can be expressed by the square of the amplitude versus frequency as follows:
where j is an imaginary number,n is the order of the filter; w (w) n Is the cut-off frequency, i.e. the frequency at which the amplitude drops to-3 db, at which time |H (w c )| 2 =1/2; in order to simplify the calculation, w is generally taken while ensuring the calculation accuracy n ＝w p ；
According to normalized passband cut-off frequency w p And stop band cut-off frequency w s The minimum order n=5 can be obtained by rounding up from the following equation:
because of the stability requirements of the system and is a real function in the time domain, s replaces jw, s=σ+jw, σ is the real part, w is the imaginary part, and the magnitude squared function |h (jw) | is written as a function of s:
the poles of H(s) must lie in the left half plane of s, the poles of H (-s) must lie in the right half plane of s, the poles of H(s) and H (-s) are symmetrically distributed on the complex plane of s 1 、s 2 …s k 、s k+1 …s N N poles representing H(s) are then
Because the boundary frequency and the filter amplitude-frequency characteristics corresponding to different technical indexes are different, the Butterworth filter adopts the frequency w cut-off of 3dB for normalizing the frequency according to a design formula n Normalization, i.e. dividing the above molecular denominator by w, respectively n N The normalized system function is
For the present invention n=5, checkThe function normalization table is obtained: a, a 1 ＝3.236068，a 2 ＝5.236068，a 3 ＝5.236068，a 4 =3.236080, d is a constant, which is a gain constant term; when s is replaced with jw, the gain |h (j 0) |=1 at this time is generally specified by |h (j 0) |=d when w=0, and therefore, d=1;
thereafter, jw is used instead ofSubstituted into->Performing inverse normalization processing on the function to obtain H (jw);
3) The signal filtered by the butterworth low-pass digital filter is q (t), q (t) =y (t) ×h (jw);
4) In order to make the signal part pointed, the recognition and the processing of the signal protruding part are facilitated, and q (t) is subjected to differential processing, wherein the processing method is as follows:
and (3) obtaining differential transformation of the first derivative, wherein t is the moment of the current sampling point, and differentiating the first derivative:
in order to find the abrupt change point of the traveling wave current more accurately, the signal r (t) needs to be modulated, namely, an envelope curve is obtained;
5) Envelope processing is carried out on the signal r (t), and the envelope curve f (t) is obtained by adopting Hilbert transformation:
all extreme points of the signal r (t) are identified, and then all maximum points and all minimum points are respectively fitted to an upper envelope curve f of r (t) 1 (t) and lower envelope f 2 (t); the extreme points are local maximum points, the derivatives of the extreme points are 0, n poles are assumed to exist, and the time corresponding to the extreme points is recorded as t according to the time sequence of the extreme points 1 ，t 2 ，t 3 …t i ,t i+1 …t n The extreme points of these time points correspond to r 1 ，r 2 ，r 3 …r i ,r i+1 …r n These extreme pointst i The corresponding time of the ith pole is represented, the envelope curve obtained by adopting a method of fitting the n extreme points by adopting a binomial equation is f (t), and the upper envelope curve and the lower envelope curve are f respectively 1 (t)、f 2 (t) fitting method adopts least square method principle, when the deviation delta i Least sum of squaresThe deviation is a fitted curve f (t i ) And extreme point r i Is the difference between (1):
n represents the number of pole points, i represents the ith pole;
6) Obtaining upper and lower envelope lines f 1 (t)、f 2 (T) obtaining the corresponding time of the maximum value points by searching, wherein the corresponding time of the two maximum value points with the minimum interval between the two time points is T respectively 1 、T 2 The first wave head position and the reflected wave head position are respectively used for obtaining a fault point distance value Q= (T) 2 -T 1 ) V/2, v is the wave velocity of the traveling wave, the wave velocity on the overhead line being close to the speed of light in vacuum, the wave velocity in the crosslinked polyethylene cable being about 170-180m/us;
7) Outputting a result: and the distance value Q between the fault point and the installation position of the traveling wave measuring device of the power transmission line.
The invention provides an accurate positioning method of a power transmission line fault and a power transmission line traveling wave measuring device based on a single-ended traveling wave ranging method, which inhibit the interference of external factors such as noise and the like on the basis of ensuring the signal processing quality; the implementation of the accurate positioning method of the power transmission line faults and the traveling wave measuring device of the power transmission line can be used for matching with the fault maintenance of the power transmission and distribution network, and reduces the power failure loss, so that the development and method research of related devices are facilitated while the power supply reliability is improved.
Drawings
FIG. 1 is a schematic diagram of a line refraction and reflection adopted by the accurate positioning method of the power transmission line fault of the invention;
FIG. 2 is a schematic diagram of signal processing of a method for precisely locating a fault in a transmission line according to the present invention;
FIG. 3 is a flowchart illustrating steps of a fault location calculation method based on an envelope curve in a method for precisely locating a fault of a power transmission line according to the present invention;
fig. 4 is a schematic diagram of a 66kV line to which the accurate positioning method of the power transmission line fault of the present invention is applied;
FIG. 5 is a schematic diagram of traveling wave current raw data;
FIG. 6 is a schematic diagram of signal filtering front-to-back analysis;
FIG. 7 is a schematic diagram of analysis before and after differential transformation of signals;
FIG. 8 is a schematic diagram of signal envelope analysis before and after;
FIG. 9 is a schematic diagram of a process for extracting the head moments of the head waves and the reflected waves based on wavelet analysis technology;
fig. 10 is a schematic circuit diagram of a traveling wave measurement device for a power transmission line according to the present invention;
fig. 11 is a graph of square amplitude versus frequency for a butterworth low pass filter.
Detailed Description
The invention provides a traveling wave measuring device of a power transmission line, which comprises the following components: the system comprises a data acquisition unit, an A/D converter, a FIFO memory, a DSP controller and a data processing unit;
the data acquisition unit is arranged at one end, namely a current input end, of the power transmission line, with high voltage, the data acquisition unit is used for acquiring fault current traveling wave signals of the power transmission line, a signal output end of the data acquisition unit is connected with an analog signal input end of the A/D converter, a digital signal output end of the A/D converter is connected with a data bus input/output end of the FIFO memory, the A/D converter is used for transmitting converted digital signals to the FIFO memory for storage, a data output end of the FIFO memory is connected with a data input end of the DSP controller, a data output end of the DSP controller is connected with a data input end of the data processing unit, and data in the FIFO memory is read by the DSP controller and transmitted to the data processing unit in real time for subsequent calculation; the data output end of the data processing unit is used for continuous transmission through a connected Ethernet interface;
the circuit schematic diagram of the transmission line traveling wave measuring device is shown in fig. 10; the data acquisition unit comprises a Rogowski coil electronic current transformer and an integrator, wherein the Rogowski coil electronic current transformer is sleeved on the periphery of the power transmission line and is used for acquiring signals; the Rogowski coil electronic current transformer is used for collecting current signals of a power transmission line, the positive electrode and the negative electrode of an output pin of the Rogowski coil electronic current transformer are correspondingly connected with a non-inverting input end and an inverting input end of an integrator respectively, and the output end of the integrator is connected with the non-inverting input end of the integrator through a capacitor and used for feedback; an inductor is connected in series between the positive electrode of the output pin of the Rogowski coil electronic current transformer and the non-inverting input end of the integrator, and is used for inhibiting high-frequency interference; the integrator is used for converting the input acquisition signal into a fault current traveling wave signal;
the A/D converter is of the model number ADS8342; the FIFO memory is of a model number of FIFO IDT72V3680; the A/D converter converts fault current travelling wave signals received by the input end into digital signals and then transmits the digital signals to the FIFO memory for storage, and the FIFO memory is also used for buffering fault signal data;
the data bus input end of the DSP controller reads in data, and then the DSP controller sends the read data into the data processing unit through the Ethernet interface of the data output end of the DSP controller, so that the data processing unit obtains fault information; the DSP controller adopts TMS320C6205 model of 32bit series in TMS320C series chip;
the invention also provides a method for accurately positioning the power transmission line fault based on the power transmission line traveling wave measurement device, which comprises the following steps:
1) A data processing unit in the travelling wave measuring device of the power transmission line reads travelling wave current data x (t), wherein the travelling wave current data is a travelling wave current value of a monitoring point in a monitoring time interval, and the travelling wave current value comprises travelling wave current in a fault state;
2) Then, the original traveling wave current data x (t) is subjected to direct current filtering by adopting an arithmetic average method, the original traveling wave current data x (t) is averaged to obtain direct current interference in the original data, and the direct current interference is recorded asFrom the original data x (t), the mean +.>Obtaining data y (t) for filtering direct current interference;
since the traveling wave current data is a high-frequency signal, to remove a low-frequency interference signal in the traveling wave current data, a butterworth digital filter is used to perform low-pass filtering on y (t), which is specifically as follows:
first, the coefficients including the pass band cut-off frequency w are set according to the frequency band range and the filtering requirement of the traveling wave signal 1 Stop band cut-off frequency w 2 Passband ripple R p And stopband attenuation R s For convenience of calculation, generally take w 1 ＝w n Sampling frequency F s =2000000 Hz, signals above 1000000Hz and 200000Hz are filtered out in view of the travelling wave signal frequency range, thus designing the passband cut-off frequency w 1 =100000 Hz, stop band cut-off frequency w 2 =200000 Hz passband ripple R p =2db, stop band attenuation R s ＝40dB。
Next, solving the analog bandpass filter index; for different cut-off frequencies w n The transfer functions of the Butterworth filters of the same order are also different, and in order to make the filter design have universality, the frequency needs to be normalized;
passband cut-off frequency normalization: w (w) p ＝1/(F s /w 1 )
Normalization of stop band cut-off frequency: w (w) s ＝2/(F s /w 2 )；
Since the butterworth filter can be expressed by the square of the amplitude versus frequency as follows:
wherein N is the order of the filter; w (w) n Is the cut-off frequency, i.e. the frequency at which the amplitude drops to-3 db, at which time |H (w c )| 2 =1/2; in order to simplify the calculation, w is generally taken while ensuring the calculation accuracy n ＝w p ；
According to normalized passband cut-off frequency w p And stop band cut-off frequency w s The minimum order n=5 can be obtained by rounding up from the following equation:
from the above analysis, a graph of the square amplitude versus frequency of the butterworth low-pass filter can be obtained as shown in fig. 11;
because of the stability requirements of the system and is a real function in the time domain, s replaces jw, s=σ+jw, σ is the real part, w is the imaginary part, and the magnitude squared function |h (jw) | is written as a function of s:
the poles of H(s) must lie in the left half plane of s, the poles of H (-s) must lie in the right half plane of s, the poles of H(s) and H (-s) are symmetrically distributed on the complex plane of s 1 、s 2 …s k 、s k+1 …s N N poles representing H(s) are then
Because the boundary frequency and the filter amplitude-frequency characteristics corresponding to different technical indexes are different, the Butterworth filter adopts the frequency w cut-off of 3dB for normalizing the frequency according to a design formula n Normalization, i.e. dividing the above molecular denominator by w, respectively n N The normalized system function is
For the present invention n=5, checkThe function normalization table is obtained: a, a 1 ＝3.236068，a 2 ＝5.236068，a 3 ＝5.236068，a 4 =3.236080, d is a constant, which is a gain constant term; when s is replaced with jw, the gain |h (j 0) |=1 at this time is generally specified by |h (j 0) |=d when w=0, and therefore, d=1;
thereafter, jw is used instead ofSubstituted into->Performing inverse normalization processing on the function to obtain H (jw);
3) The signal filtered by the Butterworth low-pass digital filter is q (t), q (t) =y (t) ×H (jw);
4) In order to make the signal part pointed, the recognition and the processing of the signal protruding part are facilitated, and q (t) is subjected to differential processing, wherein the processing method is as follows:
and (3) obtaining differential transformation of the first derivative, filtering a signal q (t) by a filter, wherein t is the current time of a sampling point, and differentiating the first derivative:
in order to find the abrupt change point of the traveling wave current more accurately, the signal r (t) needs to be modulated, namely, an envelope curve is obtained;
5) Envelope processing is carried out on the signal r (t), and the Hilbert transform is adopted to obtain an envelope curve
All extreme points of the signal r (t) are identified, and then all maximum points and all minimum points are respectively fitted to an upper envelope curve f of r (t) 1 (t) and lower envelope f 2 (t); the extreme points are local maximum points, the derivatives of the points are 0, and the time corresponding to the extreme points is recorded as t 1 ，t 2 ，t 3 …t i ,t i+1 …t n R at these time points 1 ，r 2 ，r 3 …r i ,r i+1 …r n These pointsThe envelope curve obtained by adopting the method of fitting the points by adopting a binomial equation is f (t), and the upper envelope curve and the lower envelope curve are f respectively 1 (t)、f 2 (t) fitting method adopts least square method principle, when the deviation delta i The sum of squares is minimal and the deviation is the fitted curve f (t i ) And extreme point r i Is the difference of (2)
6) Obtaining envelope f (T), obtaining corresponding time of the maximum value points of the modes through searching, wherein the corresponding time of the two maximum value points of the modes with minimum time is T 1 And T 2 The fault point distance is found to be q= (T 2 -T 1 ) V/2, v is the wave velocity of the traveling wave, the wave velocity on the overhead line being close to the speed of light in vacuum, the wave velocity in the crosslinked polyethylene cable being about 170-180m/us;
7) Outputting a result: a distance value Q between a fault point and the installation position of the traveling wave measuring device of the power transmission line; the calculation process is shown in fig. 3;
compared with the current common wavelet analysis method, the method provided by the invention has higher precision;
as shown in fig. 1, a traveling wave measuring device for a transmission line is installed at a point M of a current input end of a section of transmission line, and the traveling wave current is i as the first traveling wave measured by the traveling wave measuring device for the transmission line at the point M 1 After the fault F is reflected once, the measurement is carried out for the 2 nd time to be i 2 The traveling wave at the fault point is measured to be i by the M point for the third time after being reflected by the N point at the tail end of the power transmission line 3 However due to i 3 The transmission distance is far, attenuation and dispersion are serious, i is generally taken 1 And i 2 Fault location is performed, and then the transmission line traveling wave measuring device obtains i 1 、i 2 Time of (1)The difference is twice MF distance, and how to accurately obtain the position of the fault point F through the position of the M point; the principle of the technical scheme is that;
as shown in fig. 2, the method of the present invention is to collect signals by: filtering, differential transformation, envelope modulation and wavelet analysis techniques; the envelope modulation is to accurately determine the position of the wave head by extracting an envelope curve, so as to accurately perform fault positioning; the present example uses a 66kV line as shown in fig. 4 to specifically describe the processing and positioning method of the present invention;
FIG. 3 shows a specific processing method and process of three links including filtering, transforming and modulating in the transmission line fault accurate positioning method;
table 1 shows the corresponding recommended method and effect achieved for each link of the process flow of the method;
the method comprises the following steps:
FIG. 4 is a 66kV line, and the whole structure of the line is shown in the figure; in fig. 4, a #1 tower is an electric energy input end, and a #82 tower is installed on the traveling wave measuring device of the electric transmission line of the invention;
as shown in fig. 5, the original waveform of the current at the fault tripping moment is the main wave transmitted from the fault point collected by the tower terminal 1, and the wave speed of the traveling wave in the transmission line is about 290m/us;
the fault point is positioned by adopting the method and the wavelet analysis technology provided by the invention, and the accuracy is compared;
(1) The accurate positioning method for fault point positioning is divided into 3 links:
A. filtering
The filtering is the operation of filtering the frequency of a specific wave band in the signal, which is a main method for inhibiting interference, and the filtering link is to remove the direct current component and the high frequency component, and an arithmetic average method and a low-pass filtering method are respectively adopted; the arithmetic average method can be used for random noise, interference processing and direct current drift brought by a system, namely algebraic average of collected data samples; the low-pass filtering method adopts a Butterworth digital filter to filter out high-frequency interference signals;
because the direct current filtering eliminates the interference of direct current drift in the original signal, the graph of the direct current drift is compared before and after the filtering in fig. 6, the graph a in fig. 6 is the graph of the direct current drift before and after the filtering, and the graph b is the partial enlarged graph; the amplitude of the waveform after filtering in fig. 6 is changed compared with that of the original data before filtering (the waveform before filtering and the waveform after filtering are not changed greatly due to smaller direct current interference in the original data), and in order to more clearly see the filtering effect, the square frame part in a is partially amplified in fig. b);
B. transformation
Signal derivation, which can eliminate the background of the signal, determine the position of the spectrum peak, and improve the spectrum peak resolution, generally, in signal analysis, the commonly used signal derivation is first-order derivative and second-order derivative; here we differential transform the signal to tip the part of the signal variation so that the resulting signal is more sharp, where the differential transform of the signal is the first derivative of the input signal;
the line after differential transformation in fig. 7 becomes a line with 0 line as a reference line, and the up-down drastic fluctuation is greatly reduced;
C. modulation of
The envelope is a modulation method, the peak point of the signal after differential transformation is connected, an upper (positive) line and a lower (negative) line can be obtained, the two lines are called an envelope, as shown in fig. 8, the envelope demodulates the amplitude of the generated output signal in direct proportion to the envelope of the modulated signal, the point on the envelope is the tangent connecting line of all maximum points, and the position of the maximum point of the module, namely the position of the wave head, can be accurately determined by solving the envelope, so that the fault point positioning precision is improved;
D. fault point location
The upper and lower dots in fig. 8 are upper (positive) maximum points 596 and lower (negative) maximum points 712, respectively, to obtain the fault point location of the method of the present invention:
(2) Wavelet analysis technique
A. Wavelet decomposition
A wavelet consists of a family of wavelet basis functions that describe local characteristics of the signal time (spatial) and frequency (scale) domains; the greatest advantage of wavelet analysis is that local analysis can be performed on the signals, and the signals can be analyzed in any time or space domain; the following is that the traveling wave acquired data in this case adopts a wavelet analysis method to perform fault location calculation, and uses a multi-resolution and mode maximum characteristic of wavelet transformation as a common cable fault point location method, so as to obtain s=a3+d3+d2+d1, as shown in fig. 9; where S is the original signal, A1A 2A 3 is the approximate portion of each frequency bin signal, and D1D 2D 3 is the detailed portion of each frequency bin signal; because the traveling wave signal contains multi-frequency waveforms, the transmission of various waveforms accords with the traveling wave transmission principle, and the waveforms of various frequencies are mutually overlapped in the transmission process and the characteristics in the signal cannot be distinguished, the signal is decomposed according to different frequencies, so that the main characteristics such as the maximum value of the mode in each frequency are obtained, and the final purpose of decomposition is achieved;
B. fault point location
According to the refraction and reflection principle of the traveling wave, fault location calculation is carried out, d2 reads that the first maximum value point and the third maximum value point are 594 and 713 respectively, and the fault point position is calculated according to a calculation formula (1):
overhauling to find that the fault point is located at a distance of 8120m in the large-size direction of the small-size transformer substation, and the fault position is 38 # tower; the errors of the two methods are 290m and 507.5m respectively, which shows that the method has higher accuracy than the common wavelet analysis technology.
The accurate positioning method for the power transmission line fault has the technical key that the accurate recognition of the second reflected traveling wave head is based on the single-ended traveling wave method, and compared with the conventional method, the accurate positioning method is simple and easy to implement and has good noise suppression effect; the technical points are as follows:
1. the power transmission line can be an overhead power transmission line or a cable line;
2. the power transmission line faults comprise, but are not limited to, low-resistance ground faults, lightning stroke faults, short circuit faults, low-resistance ground faults and the like;
3. as shown in FIG. 10, the traveling wave fault positioning device realizes data acquisition, processing and transmission through hardware equipment, comprises a Rogowski coil, an A/D converter, a FIFO memory and a DSP controller, the fault ranging device of the power transmission line can realize fault monitoring of the power transmission line, the data acquisition can monitor fault traveling wave current at the moment of occurrence of the fault of the power transmission line in real time, the acquired signals are subjected to A/D conversion, the A/D conversion data are stored in an external memory and are sent to a data center for data processing, and the DSP processor can run at a speed of tens of millions of complex instruction programs per second in real time, so that the data processing rate is improved;
in the data acquisition unit, a Rogowski coil electronic current transformer can be adopted to realize signal acquisition; because the Rogowski current transformer collects the current signals of the power transmission line, an integrator can be connected again under the condition of adopting the current transformer to realize the conversion from voltage signals to current signals, thereby completing the collection of fault current traveling wave signals; the collected signals are converted by the A/D converter and then stored into the FIFO memory, and meanwhile, the buffer function is also realized on fault signal data;
the output of the FIFO memory is connected to a data bus of the controller DSP, and the controller reads the data in the FIFO and then enters a processing unit of the data, so that the fault information is presented after being processed; the choice of memory and processor depends on the situation, here a 16-bit A/D converter model ADS8342 and an IDT72V3680 model FIFO memory; the processor selects TMS320C6205 model of 32bit series in TMS320C series chip of TI company;
4. the correct identification of the second reflected traveling wave head is difficult because the single-ended traveling wave ranging is realized by installing measuring equipment on only one section of the line, and the relationship between the fault point and the distance between the fault point and the traveling wave measuring point and the reasons of signal refraction and scattering are included; the method mainly adopts the denoising and filtering of the traveling wave signals based on wavelet transformation at home and abroad, but the method needs a large amount of filtering treatment, and the calculation process is very complex; the improvement of the method ensures the signal processing quality and can accurately position faults under the condition of noise suppression;
5. the signal processing quality is ensured, and noise is suppressed by performing a series of operations including filtering, transformation, modulation and the like on the signal;
6. the filtering is to remove direct current interference on the signal; by arithmetic mean by subtracting the mean value from the original signal x (t)The direct current interference signal can be removed to obtain y (t);
7. the filtering also comprises filtering out the high-frequency interference signal by low-pass filtering, wherein a Butterworth low-pass digital filter is adopted, and the filter order n and the cut-off frequency omega are substituted c And a frequency ω -p at which the amplitude drops to-3 dB;
8. performing tip processing on the filtered signal, namely performing first-order derivation on the filtered signal;
q(t)＝r′(t)
9. and (5) solving upper and lower envelope lines, determining the positions of the head wave and the reflected wave, and further carrying out fault positioning.
The foregoing is merely illustrative embodiments of the present invention, and the scope of the present invention is not limited thereto, and any person skilled in the art can easily think about variations or substitutions within the technical scope of the present invention, and should be covered by the scope of the present invention; therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (1)
1. The transmission line fault accurate positioning method based on the transmission line traveling wave measuring device is characterized in that the transmission line traveling wave measuring device comprises the following steps: the system comprises a data acquisition unit, an A/D converter, a FIFO memory, a DSP controller and a data processing unit;
the data acquisition unit is arranged at one end, namely a current input end, of the power transmission line, with high voltage, the data acquisition unit is used for acquiring fault current traveling wave signals of the power transmission line, a signal output end of the data acquisition unit is connected with an analog signal input end of the A/D converter, a digital signal output end of the A/D converter is connected with a data bus input/output end of the FIFO memory, the A/D converter is used for transmitting converted digital signals to the FIFO memory for storage, a data output end of the FIFO memory is connected with a data input end of the DSP controller, a data output end of the DSP controller is connected with a data input end of the data processing unit, and data in the FIFO memory is read by the DSP controller and transmitted to the data processing unit in real time for subsequent calculation; the data output end of the data processing unit is used for continuous transmission through a connected Ethernet interface;
the data acquisition unit comprises a Rogowski coil electronic current transformer and an integrator, wherein the Rogowski coil electronic current transformer is sleeved on the periphery of the power transmission line and is used for acquiring signals; the Rogowski coil electronic current transformer is used for collecting current signals of a power transmission line, the positive electrode and the negative electrode of an output pin of the Rogowski coil electronic current transformer are correspondingly connected with a non-inverting input end and an inverting input end of an integrator respectively, and the output end of the integrator is connected with the non-inverting input end of the integrator through a capacitor and used for feedback; an inductor is connected in series between the positive electrode of the output pin of the Rogowski coil electronic current transformer and the non-inverting input end of the integrator, and is used for inhibiting high-frequency interference; the integrator is used for converting the input acquisition signal into a fault current traveling wave signal;
the A/D converter adopts the model number ADS8342; the FIFO memory is of a model number of FIFO IDT72V3680; the A/D converter converts fault current travelling wave signals received by the input end into digital signals and then transmits the digital signals to the FIFO memory for storage, and the FIFO memory is also used for buffering fault signal data;
the data bus input end of the DSP controller reads in data, and then the DSP controller sends the read data into the data processing unit through the Ethernet interface of the data output end of the DSP controller, so that the data processing unit obtains fault information; the DSP controller adopts TMS320C6205 model of 32bit series in TMS320C series chip;
the accurate positioning method of the power transmission line fault based on the power transmission line traveling wave measuring device comprises the following steps:
1) The data processing unit in the travelling wave measuring device of the power transmission line reads travelling wave current datax(t) The traveling wave current data is the traveling wave current value of a monitoring point in a monitoring time interval, and the traveling wave current value comprises the traveling wave current of a fault state;
2) Subsequently using arithmetic averaging to the original travelling wave current datax(t) Direct current filtering is carried out to the original travelling wave current datax(t) Averaging to obtain DC interference in the original data, and recording as(t) From the raw datax(t) Subtracting the average +.>(t) Obtaining data for filtering direct current interferencey(t)；
Because the traveling wave current data is a high-frequency signal, the surrounding low-frequency interference signals are coupled into the traveling wave current signal in the monitoring process, so that the low-frequency interference signals in the traveling wave current data are removed, the frequency response curve of the Butterworth filter in a passband is maximally flat and has no fluctuation, and gradually drops to zero in a blocking band;
the Butterworth band-pass filter is adopted for filtering, and firstly, according to the frequency band range of the traveling wave signal and the filtering requirement, the set coefficients comprise the pass band cut-off frequencyw 1 Stop band cut-off frequencyw 2 Passband ripple R p And stopband attenuation R s For the convenience of calculation and takingw 1 =w n Sampling frequencyF s =2000000 Hz, the signals above 1000000Hz and 200000Hz are filtered out in view of the travelling wave signal frequency range, thus designing the passband cut-off frequencyw 1 =100000 Hz, stop band cut-off frequencyw 2 =200000 Hz passband ripple R p =2db, stop band attenuation R s =40dB；
Next, solving the analog bandpass filter index; for different cut-off frequenciesw n The transfer functions of the Butterworth filters of the same order are also different, and in order to make the filter design have universality, the frequency needs to be normalized;
passband cut-off frequency normalization:，
normalization of stop band cut-off frequency:；
since the butterworth filter can be expressed by the square of the amplitude versus frequency as follows:
（1）
where j is an imaginary number, j=N is the order of the filter；w n Is the cut-off frequency, i.e. the frequency at which the amplitude drops to-3 db, at which time |H #w c )| 2 =1/2; to simplify the calculation and take under the condition of ensuring the calculation accuracyw n = w p ；
According to normalized passband cut-off frequencyw p And stop band cut-off frequencyw s The minimum order n=5 can be obtained by rounding up from the following equation:
，
because of the stability requirements of the system and the real function in the time domain, s is used instead of jw，s=σ+ jw, σ is the real part, w is the imaginary partThe amplitude square function |H (jw) The i is written as a function of s:
，
the poles of H(s) must lie in the left half plane of s, the poles of H (-s) must lie in the right half plane of s, the poles of H(s) and H (-s) are symmetrically distributed on the complex plane of s 1、 s 2··· s k、 s k+1··· s N N poles representing H(s) are then
，
Because the boundary frequencies corresponding to different technical indexes and the amplitude-frequency characteristics of the filter are different, the Butterworth filter adopts the frequency cut-off of 3dB to normalize the frequency in order to ensure that the design formulaw n Normalization, i.e. dividing the above molecular denominator byThe normalized system function is
，
For n=5, look up H #) The function normalization table is obtained:a 1 =3.236068，a 2 =5.236068，a 3 =5.236068，a 4 =3.236080，dis a constant, which is a gain constant term; when in usejwSubstitution ofsAt the time, bywWhen=0 |h (j 0) |=dAt this time, the gain |h (j 0) |=1 is specified, and therefore,d=1；
thereafter, with jwSubstitution ofSubstituted into->The function is subjected to inverse normalization processing to obtain H (j)w)；
3) The signal after being filtered by the Butterworth low-pass digital filter isq(t)，q(t)=y(t)*H(jw)；
4) In order to make the signal part pointed, the signal protruding part is further identified and processedq(t) Differential processing is carried out, and the processing method is as follows:
a differential transformation of the first derivative is obtained,tis the current sampling point moment, and the first derivative is differentiated:
，
in order to find the abrupt change point of the traveling wave current more accurately, the signal is needed to be processedr(t) Modulating, namely obtaining an envelope curve;
5) To signalr(t) Envelope processing is carried out, and Hilbert transformation is adopted to obtain an envelope curvef(t)：
First, the signal is identifiedr(t) All extreme points of (2) then use all polesFitting the large value point and all the small value points respectivelyr(t) Upper envelope of (a)f 1 (t) And lower envelope curvef 2 (t) The method comprises the steps of carrying out a first treatment on the surface of the The extreme points are local maximum points, the derivatives of the extreme points are 0, n poles are assumed to exist, and the time corresponding to the extreme points is recorded as the time of the extreme pointst 1 ，t 2 ，t 3 …t i , t i+1 … t n The extreme points of these time points correspond tor 1 ，r 2 ，r 3 …r i , r i+1 … r n These extreme points| t t=i =0，t i Representing the corresponding time of the ith pole, and adopting a binomial equation to fit the n extreme points to obtain an envelope curve asf (t) The upper and lower envelope lines are respectivelyf 1 (t)、f 2 (t) The fitting method adopts the principle of least square method, when the deviation isδ i The square sum is minimum, and the deviation is a fitting curvef (t i ) And extreme pointr i Is the difference between (1):
，
n represents the number of pole points, i represents the ith pole;
6) Obtaining upper and lower envelope linesf 1 (t)、f 2 (t) Obtaining the corresponding time of the maximum value points by searching, wherein the corresponding time of the two maximum value points with the minimum interval between the two time points is T respectively 1 、T 2 The first wave head position and the reflected wave head position are respectively used for obtaining a fault point distance value Q= (T) 2 - T 1 )· v/2，vThe wave speed of the traveling wave is close to the light speed in vacuum, and the wave speed in the crosslinked polyethylene cable is 170-180m/us;
7) Outputting a result: and the distance value Q between the fault point and the installation position of the traveling wave measuring device of the power transmission line.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110075763A (en) * | 2009-12-29 | 2011-07-06 | 주식회사 효성 | Method for detecting fault location on transmission line using second-order differential of travelling waves |
| CN202075370U (en) * | 2011-05-21 | 2011-12-14 | 山东大学 | Traveling wave fault ranging device based on Rogowski coil differential output |
| CN102353875A (en) * | 2011-09-30 | 2012-02-15 | 山东理工大学 | Fault distance measuring method for combined travelling wave of power transmission line |
| CN103901324A (en) * | 2014-04-14 | 2014-07-02 | 国家电网公司 | Method for hybrid circuit combined distance measurement of power distribution network based on single-ended fault information |
| CN105548739A (en) * | 2015-12-04 | 2016-05-04 | 江苏省电力公司宿迁供电公司 | Processing method of running state signal of arrester |
| CN108152674A (en) * | 2017-12-21 | 2018-06-12 | 国网宁夏电力公司中卫供电公司 | A kind of feature based point identification and the fault traveling wave filtering method of linear interpolation |
| CN110632465A (en) * | 2019-11-13 | 2019-12-31 | 西南石油大学 | HHT (Hilbert-Huang transform) normalized iteration-based high-voltage direct-current transmission line fault distance measurement method |
| CN110794337A (en) * | 2019-12-18 | 2020-02-14 | 烟台科大正信电气有限公司 | Small current grounding fault judgment method and fault recording system |
| CN112147457A (en) * | 2019-06-26 | 2020-12-29 | 国网江苏省电力有限公司南京供电分公司 | Underground comprehensive pipe gallery cable fault detection and positioning system and method based on Hilbert-Huang transform |
| CN113484667A (en) * | 2021-06-22 | 2021-10-08 | 佳源科技股份有限公司 | Flexible direct-current power distribution network fault positioning scheme applied to distribution network terminal |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080077336A1 (en) * | 2006-09-25 | 2008-03-27 | Roosevelt Fernandes | Power line universal monitor |
| CN102288932B (en) * | 2011-05-10 | 2015-03-04 | 山东电力研究院 | Method for accurately measuring lightning strike fault waveform of power transmission line |
| CN202159093U (en) * | 2011-07-07 | 2012-03-07 | 海南电力试验研究所 | Transmission line malfunction traveling wave current full wave collecting device |
| CN202267707U (en) * | 2011-07-12 | 2012-06-06 | 广东电网公司电力科学研究院 | High-frequency traveling wave current signal collecting circuit |
| CN104965155B (en) * | 2015-06-26 | 2018-05-01 | 国家电网公司 | A kind of wave head lookup method based on filtering characteristic |
| CN110133445A (en) * | 2019-06-10 | 2019-08-16 | 集美大学 | A kind of submarine cable fault distance-finding method, terminal device and storage medium |
-
2022
- 2022-06-15 CN CN202210675502.9A patent/CN115267417B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20110075763A (en) * | 2009-12-29 | 2011-07-06 | 주식회사 효성 | Method for detecting fault location on transmission line using second-order differential of travelling waves |
| CN202075370U (en) * | 2011-05-21 | 2011-12-14 | 山东大学 | Traveling wave fault ranging device based on Rogowski coil differential output |
| CN102353875A (en) * | 2011-09-30 | 2012-02-15 | 山东理工大学 | Fault distance measuring method for combined travelling wave of power transmission line |
| CN103901324A (en) * | 2014-04-14 | 2014-07-02 | 国家电网公司 | Method for hybrid circuit combined distance measurement of power distribution network based on single-ended fault information |
| CN105548739A (en) * | 2015-12-04 | 2016-05-04 | 江苏省电力公司宿迁供电公司 | Processing method of running state signal of arrester |
| CN108152674A (en) * | 2017-12-21 | 2018-06-12 | 国网宁夏电力公司中卫供电公司 | A kind of feature based point identification and the fault traveling wave filtering method of linear interpolation |
| CN112147457A (en) * | 2019-06-26 | 2020-12-29 | 国网江苏省电力有限公司南京供电分公司 | Underground comprehensive pipe gallery cable fault detection and positioning system and method based on Hilbert-Huang transform |
| CN110632465A (en) * | 2019-11-13 | 2019-12-31 | 西南石油大学 | HHT (Hilbert-Huang transform) normalized iteration-based high-voltage direct-current transmission line fault distance measurement method |
| CN110794337A (en) * | 2019-12-18 | 2020-02-14 | 烟台科大正信电气有限公司 | Small current grounding fault judgment method and fault recording system |
| CN113484667A (en) * | 2021-06-22 | 2021-10-08 | 佳源科技股份有限公司 | Flexible direct-current power distribution network fault positioning scheme applied to distribution network terminal |
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