CN115902530A - Earth electrode line fault distance measurement method and system - Google Patents
Earth electrode line fault distance measurement method and system Download PDFInfo
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Abstract
The invention relates to a method and a system for measuring the distance of a grounding electrode line fault, and belongs to the technical field of power system relay protection. The method comprises the steps of firstly injecting a pulse signal into an earth electrode line by using a signal generator, deducing a mathematical expression of a traveling wave head according to a traveling wave grid diagram, setting virtual fault points in a full-line length range, constructing a virtual matrix, calculating the energy of the virtual fault points, and determining the fault distance according to the maximum value of the energy and the polarity of the value. Compared with the prior art, the method does not need to identify the property of the second wave head, and has higher reliability.
Description
Technical Field
The invention relates to a method and a system for measuring the distance of a grounding electrode line fault, and belongs to the technical field of power system relay protection.
Background
The grounding electrode system is a unique and indispensable important component in an ultra (special) high-voltage direct-current transmission system and consists of a grounding electrode circuit and a grounding electrode address, wherein the grounding electrode circuit usually adopts parallel overhead lines. In order to prevent the interference of the grounding current of the grounding electrode to the alternating current side system, the grounding point of the grounding electrode address is generally away from the converter station by dozens of kilometers or even more than one hundred kilometers. The main function of the grounding electrode line is to provide a path for direct current, and the normal operation of a direct current transmission system can be directly influenced when the grounding electrode line fails. When the grounding electrode line has a fault, the direct current arc does not have a natural zero crossing point, the direct current arc is not easy to extinguish, and the direct current system needs to be stopped to extinguish the arc, so that the fault position is quickly determined, and the safe and stable operation of the direct current transmission system is ensured when the fault is eliminated. However, under the condition of bipolar symmetrical operation of a direct current system, unbalanced current and system neutral point potential in an earth electrode line are very small, and earth electrode address resistance is also very small, so that once the earth electrode line fails, the fault additional component and fault characteristics of the earth electrode line are very small, and the traditional online passive fault detection and positioning technology and device are difficult to start, and the method is not applicable any more.
Disclosure of Invention
The invention aims to solve the technical problem of providing a grounding electrode line fault location method and a system thereof, which are used for solving the problems that the traditional passive fault detection and location technology is difficult to start and the existing method cannot accurately calibrate the arrival time of a traveling wave head to cause inaccurate location.
The technical scheme of the invention is as follows: a method for measuring the fault of grounding electrode line features that a pulse signal generator is connected to the measuring end of grounding electrode line, and the pulse signal is used as the traveling wave source to be injected to the grounding electrode line for realizing the fault measurement of grounding electrode line in balanced running mode. Because the distance between the first wave head and the second wave head of the line mode voltage traveling wave is 2 times of the fault distance, the first wave head moves rightwards to form a first virtual matrix, the second wave head moves leftwards to form a second virtual matrix, when the first wave head of the first wave head meets the second wave head of the second wave head, the two wave heads move 1 time of the fault distance respectively, therefore, the distance measurement function forms the maximum catastrophe point at the meeting position of the wave heads, and the point is the point reflecting the fault distance information.
The method comprises the following specific steps:
step1: and injecting a pulse signal into the grounding electrode line by using the signal generator. The basis for executing the step is that when the parameters of the double poles in the high-voltage direct-current transmission system are symmetrical and the double poles run in a balanced mode, the grounding pole line is in a zero-voltage zero-current state, and when the grounding pole line fails, a fault traveling wave signal cannot be generated at a fault point, so that a pulse signal generating device needs to be connected to a measuring end of the grounding pole line, and the pulse signal is used as a traveling wave source to be injected into the grounding pole line, so that the fault location of the grounding pole line in the balanced mode is realized. The signal generated by the signal generator is coupled to the grounding electrode circuit through the capacitor C, the capacitor presents low impedance to the high-frequency pulse signal and high impedance to the power frequency direct current, and the direct current of the grounding electrode lead in a normal working state is prevented from entering the fault monitoring device, so that the equipment is prevented from being damaged.
Step2: and acquiring fault voltage traveling wave data by using a signal acquisition device according to the response of the pulse signal at the fault point.
Step2.1: and collecting the fault traveling wave signal of the line by using a collecting device at the earth electrode line station end. The implementation method of the step is that in an earth electrode line of a direct current transmission system in actual operation, current needs to be obtained by adopting an optical mutual inductor for transmission, the cutoff frequency of the current is usually not more than 10kHz, and current traveling waves cannot be obtained by the current. Therefore, the neutral bus is provided with the overvoltage capacitor absorber, when the line has a fault, current traveling waves can flow through the capacitor, and the traveling waves are obtained by sleeving the overvoltage capacitor absorber branch with the hollow coil CT.
Step2.2: decoupling the fault traveling wave signal by using the Karenbauer transformation matrix to obtain the line mode voltage traveling wave of the grounding electrode line. This step is performed based on the fact that the line mode component is zero when the earth electrode line is not faulty, and only the zero mode component exists, whereas the line mode component is no longer zero when the earth electrode line is faulty. When the zero-mode component is transmitted to the pole address point, most of reflected waves of the zero-mode component are absorbed by the pole address resistor, so that zero-mode voltage and current reflected by the pole address point are difficult to detect and capture at a measuring end, secondly, the attenuation characteristics of the zero-mode and the line mode change greatly along with the frequency, the pass band of a line mode channel is very wide, the distortion of the line mode component is very small, and the pass band of the zero-mode channel is very narrow and is easy to distort. And considering that the pulse signals injected into the two loops of the grounding electrode are equal in size and same in polarity, when the grounding electrode circuit fails, the line mode component is zero, and when the grounding electrode circuit fails, the initial pulse signals are eliminated after being subjected to line mode conversion, so that the influence of the initial traveling wave on the reflected wave is eliminated, and therefore the line mode component is utilized for fault location of the grounding electrode circuit.
Step3: and performing odd power transformation on the fault voltage traveling wave signal. The advantage of performing this step is that the characteristics of the fault voltage signal are amplified by odd power transformation and the polarity of the wave head is preserved. Because the wave head polarity of the reflected wave of the fault point is opposite to that of the first wave head, and the wave head polarity of the reflected wave of the bus at the opposite end is the same as that of the first wave head, the property of the second wave head can be distinguished by keeping the wave head polarity.
Step4: and setting virtual fault points in the full line length range, and constructing a virtual matrix. The step is executed, and the method has the advantages that the traveling wave head is not required to be calibrated, the fault voltage traveling wave is only required to be mapped to each virtual fault condition to form a virtual matrix, and the real fault distance is approximated by setting the number of virtual fault points.
Step4.1: and setting a virtual fault point in the range of the full line length l, wherein the step length is akm.
Step4.2: the fault travelling wave signal moves to the right by k (k =1,2,3, …, l/a) times of step size to form the k-th row of the first virtual matrix. Fault traveling wave signal f 1 (t), the first virtual matrix is:
step4.3: the fault traveling wave signal is shifted to the left by k (k =1,2,3, …, l/a) times step size, forming the k-th row of the second virtual matrix. Fault traveling wave signal f 1 (t), the second virtual matrix is:
step5: based on the virtual matrix, the energy of the virtual fault point is calculated. The advantage of executing this Step is that due to the attenuation characteristic of the traveling wave, the wave head amplitude of the fault voltage traveling wave is attenuated, so when the first wave head in the first virtual matrix meets the second wave head in the second virtual matrix in Step4, the energy value is the largest, and the distance corresponding to this point is the real fault distance.
Step5.1: the product of the first virtual matrix and the second virtual matrix is calculated. The Hadamard product matrix of the two virtual matrices is
：
Step5.2: the energy of each virtual fault point is calculated. The specific calculation method is that each row in the matrix C corresponds to one virtual fault point, and the sum of the energy of all the catastrophe points under each virtual fault point can be obtained by summing each row.
Step6: and constructing a ranging function, calibrating a catastrophe point in the ranging function, and determining the fault distance by using the catastrophe point.
Step6.1: and constructing a fault ranging function of the grounding electrode line. The ranging function is a piecewise function comprising two dimensions of time and distance, the lower limit of the line length dimension of the first ranging function is the starting point of the line, the upper limit of the line length dimension is the middle point of the line, the lower limit of the time dimension is the sudden change time of the fault signal at the measuring end, and the upper limit of the time dimension is the time corresponding to l/2v after the sudden change of the fault signal. The lower limit of the line length dimension of the second-stage distance measurement function is the line midpoint, the upper limit is the line end point, the lower limit of the time dimension is the time corresponding to l/2v after the fault signal is suddenly changed, and the upper limit is the time corresponding to l/v after the fault signal is suddenly changed.
Step6.2: and calibrating a point P (x, y) with the maximum mutation in the ranging function. This is performed based on the fact that when the first header of the first waveform meets the second header of the second waveform, the corresponding row in the Hadamard product matrix in this virtual case gets the maximum value, and because of the attenuation characteristics of the traveling wave, the Hadamard Ma Chengji values are relatively small when the first header of the first waveform meets the other headers of the second waveform.
Step6.3: and judging whether the polarity of the mutation point is negative, if so, executing Step6.4, and if not, executing Step6.5. This step is performed based on the fact that the first wave head of the fault signal has the opposite polarity to the second wave head.
Step6.4: the ranging result is x.
Step6.5: the ranging result is l-x.
An earth electrode line fault location system, comprising:
and the pulse signal generating module is used for injecting a pulse signal into the line.
And the electrical signal acquisition module is used for acquiring and storing data.
And the numerical value calculation module is used for calculating the virtual matrix and the energy of the virtual fault point.
And the fault distance measurement module is used for constructing a piecewise function and carrying out fault distance measurement by using the piecewise function mutation point to obtain a fault distance measurement result.
The earth electrode line fault distance measuring system is characterized in that the pulse signal generating module comprises:
and the pulse signal type selection unit is used for selecting the type of the injection pulse signal.
And the pulse signal width selection unit is used for selecting the width of the injection pulse signal.
And the pulse signal interval selection unit is used for selecting the interval of the injection pulse signal.
And the pulse signal amplitude selecting unit is used for selecting the amplitude of the injection pulse signal.
Earthing pole line fault ranging system, its characterized in that electric signal acquisition module includes:
and the data acquisition unit is used for acquiring the analog signal output by the secondary side of the mutual inductor.
And the analog-to-digital conversion unit is used for converting the analog signal into a digital signal.
And the protection starting unit is used for judging whether the digital signal is greater than a set starting threshold value or not, and if so, reading the starting time and storing data.
The earth electrode line fault distance measuring system is characterized in that the numerical calculation module comprises:
and the line-mode conversion unit is used for calculating the line-mode component of the voltage traveling wave at the measuring end.
And the parameter setting unit is used for setting the step length of the virtual fault point and the length of the grounding electrode line.
And the numerical value calculating unit is used for calculating the virtual matrix and the fault distance measuring piecewise function.
Earthing pole line fault ranging system, its characterized in that fault ranging module specifically includes:
and the distance measuring unit is used for measuring the distance corresponding to the maximum mutation point of the piecewise function.
And the polarity judging unit is used for judging the polarity of the maximum mutation point of the piecewise function.
The invention has the beneficial effects that:
1. the invention breaks through the bottleneck of calibrating the arrival time of the traveling wave in the time domain, and is easy to realize the automatic single-ended traveling wave distance measurement of the grounding electrode circuit.
2. The invention does not need to set a setting value, thereby avoiding the distance measurement error caused by the setting value.
3. The invention does not need to manually analyze the reflected wave of the fault point, thereby improving the efficiency and the accuracy of fault location.
4. The invention has the advantages that the distance measurement precision is not influenced by fault distance, transition resistance and noise, and the robustness is better.
Drawings
FIG. 1 is a simulation model topology of the present invention;
FIG. 2 is a schematic diagram of the signal generator injecting a signal to the ground electrode in Step1 according to the present invention;
FIG. 3 is a schematic diagram showing the propagation of the response of the injection signal at the fault point in Step2 according to the present invention;
FIG. 4 is a schematic diagram of the virtual fault point energy calculation in Step5 of the present invention;
FIG. 5 is a graph showing the results of the first ranging function in embodiment 1 of the present invention;
FIG. 6 is a graph showing the results of the second ranging function in embodiment 1 of the present invention;
FIG. 7 is a system block diagram of embodiment 1 of the present invention;
FIG. 8 is a graph showing the results of the first ranging function in embodiment 2 of the present invention;
FIG. 9 is a diagram showing the results of the second ranging function in embodiment 2 of the present invention.
Detailed Description
The invention is further described with reference to the following drawings and detailed description.
Example 1: a simulation model system of a high-voltage direct-current transmission system with an earth electrode line is shown in figure 1, the whole line of the line is 80km long, the earth electrode line adopts a same-tower double-circuit overhead line, and is grounded through a resistor with a small resistance value of an electrode address point, and the resistance value is generally not more than 0.5 omega. And a fault point distance measuring point is 14km is arranged on a grounding polar line, the fault type is a non-metallic grounding fault, the transition resistance is 1 omega, and the sampling rate is 1MHz.
The method comprises the following specific steps:
step1: and injecting a pulse signal into the grounding electrode line by using the signal generator. The signal injected in this example is a 100kHz high frequency sinusoidal signal with a pulse width of 16us, a pulse interval of 1.1ms and a pulse amplitude of 48V.
Step2: and acquiring fault voltage traveling wave data by using a signal acquisition device according to the response of the pulse signal at the fault point.
Step2.1: and collecting the fault traveling wave signal of the line by using a collecting device at the station end of the grounding electrode line.
Step2.2: and decoupling the fault traveling wave signal by using a Karenbauer transformation matrix to obtain the line mode voltage traveling wave of the grounding electrode line.
Step3: and performing odd power transformation on the fault voltage traveling wave signal. In the present embodiment, the number of power conversion takes 3.
Step4: setting virtual fault points in the whole line length range, and constructing a virtual matrix;
step4.1: and setting a virtual fault point in the range of the full line length l, wherein the step length is akm. In this embodiment, the length of the line l is 80km, and the step length a is 0.1km.
Step4.2: the fault traveling wave signal moves to the right k (k =1,2,3, …, l/a) times of step size, and the k-th row of the first virtual matrix is formed. Fault traveling wave signal f 1 (t), the first virtual matrix is:
step4.3: the fault traveling wave signal is shifted to the left by k (k =1,2,3, …, l/a) times step size, forming the k-th row of the second virtual matrix. Fault traveling wave signal f 1 (t), the second virtual matrix is:
step5: calculating the energy of a virtual fault point based on the virtual matrix;
step5.1: the product of the first virtual matrix and the second virtual matrix is calculated. The Hadamard product matrix of the two virtual matrices is
：
Step5.2: the energy of each virtual fault point is calculated.
Step6: constructing a distance measurement function, calibrating a catastrophe point in the distance measurement function, and determining a fault distance by using the catastrophe point;
step6.1: and constructing a fault ranging function of the grounding electrode line. In this embodiment, the lower limit of the linear length dimension of the first distance measurement function is 0, the upper limit is 40km, and the lower limit of the time dimension is the sudden change time t of the fault signal of the measurement end 0 The upper limit is (t) 0 + l/2 v), wave speed v =298km/ms; the lower limit of the linear dimension of the second distance measuring function is 40km, the upper limit is 80km, and the lower limit of the time dimension is (t) 0 + l/2 v) with an upper limit of (t) 0 +l/v)。
The specific expression of the first-stage ranging function is as follows:
the specific expression of the second range function is as follows:
step6.2: and calibrating a point P (x, y) with the maximum mutation in the ranging function. In this embodiment, the distance corresponding to the maximum mutation point in the first ranging function is 14km, as shown in fig. 5; the maximum discontinuity point in the second range function corresponds to a distance of 66km, as shown in fig. 6.
Step6.3: and judging whether the polarity of the mutation point is negative, if so, the ranging result is x, and if not, the ranging result is l-x. In this embodiment, if the polarity of the maximum mutation point of the first ranging function is negative, it is determined that the fault distance is 14km and there is no ranging error; and if the polarity of the maximum mutation point of the second distance measurement function is positive and the distance corresponding to the mutation point is 66km, judging that the fault distance is 80-66=14km.
Compared with the traditional single-ended traveling wave distance measurement method, the distance measurement method has higher distance measurement precision, and the comparison result is shown in table 1.
TABLE 1
Fig. 7 is a functional block diagram of a grounding electrode line fault location system provided by the present invention, which includes:
the pulse signal generating module is used for injecting a pulse signal into the line;
the electric signal acquisition module is used for acquiring and storing data;
the numerical value calculation module is used for calculating the energy of the virtual matrix and the virtual fault point;
and the fault distance measurement module is used for constructing a piecewise function and carrying out fault distance measurement by using the piecewise function mutation point to obtain a fault distance measurement result.
The earth electrode line fault distance measuring system is characterized in that the pulse signal generating module comprises:
a pulse signal type selection unit for selecting the type of the injection pulse signal, in this embodiment, selecting a 100kHz high frequency sinusoidal signal;
a pulse signal width selection unit for selecting the width of the injection pulse signal, which is 16us in the present embodiment;
a pulse signal interval selection unit for selecting an interval of injecting a pulse signal, in this embodiment, the pulse interval is 1.1ms;
and a pulse signal amplitude selecting unit for selecting the amplitude of the injection pulse signal, wherein the pulse amplitude is 48V in the embodiment.
Earthing pole circuit fault ranging system, its characterized in that electric signal acquisition module includes:
the data acquisition unit is used for acquiring analog signals output by the secondary side of the mutual inductor;
the analog-to-digital conversion unit is used for converting the analog signal into a digital signal;
and the protection starting unit is used for judging whether the digital signal is greater than a set starting threshold value or not, and if so, reading the starting time and storing data.
The earth electrode line fault distance measuring system is characterized in that the numerical calculation module comprises:
the line-mode conversion unit is used for calculating a line-mode component of the voltage traveling wave at the measurement end;
the parameter setting unit is used for setting the step length of the virtual fault point and the length of the grounding electrode line, wherein in the embodiment, the step length of the virtual fault point is 0.1km, and the length of the grounding electrode line is 80km;
and the numerical value calculating unit is used for calculating the virtual matrix and the fault distance measuring piecewise function.
Earthing pole line fault ranging system, its characterized in that fault ranging module specifically includes:
the distance measuring unit is used for measuring the distance corresponding to the maximum mutation point of the piecewise function; in the embodiment, the distance corresponding to the maximum catastrophe point in the first distance measurement function is 14km; the distance corresponding to the maximum mutation point in the second distance measurement function is 60km.
And the polarity judging unit is used for judging the polarity of the maximum mutation point of the piecewise function. In this embodiment, if the polarity of the maximum mutation point of the first ranging function is negative, it is determined that the fault distance is 14km and there is no ranging error; and if the polarity of the maximum mutation point of the second distance measurement function is positive and the distance corresponding to the mutation point is 66km, judging that the fault distance is 80-66=14km.
Example 2: a simulation model system of a high-voltage direct-current transmission system with an earth electrode line is shown in figure 1, the whole line of the line is 80km long, the earth electrode line adopts a same-tower double-circuit overhead line, and is grounded through a resistor with a small resistance value of an electrode address point, and the resistance value is generally not more than 0.5 omega. And a fault point distance measuring point is 14km is arranged on the grounding polar line, the fault type is nonmetallic grounding fault, the transition resistance is 1 omega, and the sampling rate is 1MHz.
The method comprises the following specific steps:
step1: and injecting a pulse signal into the grounding electrode line by using the signal generator. The signal injected in this embodiment is a unipolar pulse signal, the pulse width is 32us, the pulse interval is 1.1ms, and the pulse amplitude is 48V.
Step2: and acquiring fault voltage traveling wave data by using a signal acquisition device according to the response of the pulse signal at the fault point.
Step2.1: and collecting the fault traveling wave signal of the line by using a collecting device at the earth electrode line station end.
Step2.2: and decoupling the fault traveling wave signal by using a Karenbauer transformation matrix to obtain the line mode voltage traveling wave of the grounding electrode line.
Step3: and performing odd power transformation on the fault voltage traveling wave signal. In the present embodiment, the number of power conversion takes 3.
Step4: setting virtual fault points in the whole line length range, and constructing a virtual matrix;
step4.1: and setting a virtual fault point in the range of the full line length l, wherein the step length is akm. In this embodiment, the length of the line l is 80km, and the step length a is 0.1km.
Step4.2: the fault traveling wave signal moves to the right k (k =1,2,3, …, l/a) times of step size, and the k-th row of the first virtual matrix is formed. Fault travelling wave signal f 1 (t), the first virtual matrix is:
step4.3: the fault traveling wave signal is shifted to the left by k (k =1,2,3, …, l/a) times step size, forming the k-th row of the second virtual matrix. Fault traveling wave signal f 1 (t), the second virtual matrix is:
step5: calculating the energy of a virtual fault point based on the virtual matrix;
step5.1: the product of the first virtual matrix and the second virtual matrix is calculated. The Hadamard product matrix of the two virtual matrices is
：
Step5.2: the energy of each virtual fault point is calculated.
Step6: constructing a distance measurement function, calibrating a catastrophe point in the distance measurement function, and determining a fault distance by using the catastrophe point;
step6.1: and constructing a fault ranging function of the grounding electrode line. In this embodiment, the lower limit of the linear length dimension of the first distance measurement function is 0, the upper limit is 40km, and the lower limit of the time dimension is the sudden change time t of the fault signal of the measurement end 0 The upper limit is (t) 0 + l/2 v), wave speed v =298km/ms; the lower limit of the line length dimension of the second distance measuring function is 40km, the upper limit is 80km, and the lower limit of the time dimension is (t) 0 + l/2 v) with an upper limit of (t) 0 +l/v)。
The specific expression of the first-stage ranging function is as follows:
the specific expression of the second range function is as follows:
step6.2: and calibrating a point P (x, y) with the maximum mutation in the ranging function. In this embodiment, the distance corresponding to the maximum discontinuity point in the first ranging function is 35km, as shown in fig. 8, and the distance corresponding to the maximum discontinuity point in the second ranging function is 45km, as shown in fig. 9.
Step6.3: and judging whether the polarity of the mutation point is negative, if so, the ranging result is x, and if not, the ranging result is l-x. In this embodiment, if the polarity of the maximum mutation point of the first ranging function is negative, it is determined that the fault distance is 35km and no ranging error exists; and if the polarity of the maximum mutation point of the second distance measurement function is positive and the distance corresponding to the mutation point is 45km, judging that the fault distance is 80-45=35km.
Fig. 7 is a functional block diagram of a ground electrode line fault location system provided in the present invention, which includes:
the pulse signal generating module is used for injecting a pulse signal into the line;
the electric signal acquisition module is used for acquiring and storing data;
the numerical value calculation module is used for calculating the energy of the virtual matrix and the virtual fault point;
and the fault distance measurement module is used for constructing a piecewise function and carrying out fault distance measurement by using the piecewise function mutation point to obtain a fault distance measurement result.
The earth electrode line fault distance measuring system is characterized in that the pulse signal generating module comprises:
a pulse signal type selection unit for selecting the type of the injection pulse signal, and selecting a unipolar pulse signal in this embodiment;
a pulse signal width selection unit for selecting the width of the injection pulse signal, which is 32us in this embodiment;
a pulse signal interval selection unit for selecting an interval of injecting a pulse signal, in this embodiment, the pulse interval is 1.1ms;
a pulse signal amplitude selecting unit for selecting the amplitude of the injection pulse signal, in this embodiment the pulse amplitude is 48V.
Earthing pole line fault ranging system, its characterized in that electric signal acquisition module includes:
the data acquisition unit is used for acquiring analog signals output by the secondary side of the mutual inductor;
the analog-to-digital conversion unit is used for converting the analog signal into a digital signal;
and the protection starting unit is used for judging whether the digital signal is greater than a set starting threshold value or not, and if so, reading starting time and storing data.
The earth electrode line fault distance measuring system is characterized in that the numerical calculation module comprises:
the line-mode conversion unit is used for calculating the line-mode component of the voltage traveling wave at the measuring end;
the parameter setting unit is used for setting the step length of the virtual fault point and the length of the grounding electrode line, wherein in the embodiment, the step length of the virtual fault point is 0.1km, and the length of the grounding electrode line is 80km;
and the numerical value calculating unit is used for calculating the virtual matrix and the fault distance measuring piecewise function.
Earthing pole line fault ranging system, its characterized in that fault ranging module specifically includes:
and the distance measuring unit is used for measuring the distance corresponding to the maximum mutation point of the piecewise function. In this embodiment, the distance corresponding to the maximum mutation point in the first ranging function is 35km, and the distance corresponding to the maximum mutation point in the second ranging function is 45km.
And the polarity judging unit is used for judging the polarity of the maximum mutation point of the piecewise function. In this embodiment, if the polarity of the maximum mutation point of the first ranging function is negative, it is determined that the fault distance is 35km and no ranging error exists; and if the polarity of the maximum mutation point of the second distance measurement function is positive and the distance corresponding to the mutation point is 45km, judging that the fault distance is 80-45=35km.
Verification shows that the method and the system for measuring the distance of the earth electrode line fault have high reliability.
While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit and scope of the present invention.
Claims (12)
1. A grounding electrode line fault distance measurement method is characterized in that:
step1: injecting a pulse signal into the grounding electrode circuit by using a signal generator;
step2: acquiring fault voltage traveling wave data by using a signal acquisition device according to the response of the pulse signal at a fault point;
step3: performing odd power transformation on the fault voltage traveling wave signal;
step4: setting virtual fault points in the whole line length range, and constructing a virtual matrix;
step5: calculating the energy of a virtual fault point based on the virtual matrix;
step6: and constructing a ranging function, calibrating a catastrophe point in the ranging function, and determining the fault distance by using the catastrophe point.
2. The earth electrode line fault ranging method according to claim 1, characterized in that: in Step1, the injected pulse signal is a unipolar rectangular pulse signal or a high-frequency sinusoidal pulse signal.
3. The earth electrode line fault location method according to claim 1, wherein Step2 is specifically:
step2.1: collecting fault traveling wave signals of the line by using a collecting device at the station end of the grounding electrode line;
step2.2: and decoupling the fault traveling wave signal by using a Karenbauer transformation matrix to obtain the line mode voltage traveling wave of the grounding electrode line.
4. The earth electrode line fault location method according to claim 1, wherein Step4 is specifically:
step4.1: setting a virtual fault point within the range of the whole line length l, wherein the step length is akm;
step4.2: the fault traveling wave signal moves to the right k times by step length, k =1,2,3, …, l/a, and the k-th row of the first virtual matrix is formed;
step4.3: the fault travelling wave signal moves to the left by k steps, k =1,2,3, …, l/a, and forms the k-th row of the second virtual matrix.
5. The earth electrode line fault location method according to claim 1, wherein Step5 is specifically:
step5.1: calculating the product of the first virtual matrix and the second virtual matrix;
step5.2: the energy of each virtual fault point is calculated.
6. The earth electrode line fault location method according to claim 1, wherein Step6 is specifically:
step6.1: constructing a fault location function of the grounding electrode circuit;
step6.2: calibrating a point P (x, y) with the maximum mutation in the ranging function;
step6.3: judging whether the polarity of the mutation point is negative, if so, executing Step6.4, otherwise, executing Step6.5;
step6.4: the distance measurement result is x;
step6.5: the ranging result is l-x.
7. The earth electrode line fault location method of claim 6, wherein the constructing an earth electrode fault location function is specifically:
the ranging function is a piecewise function comprising two dimensions of time and distance, the lower limit of the line length dimension of the first ranging function is the starting point of the line, the upper limit of the line length dimension is the middle point of the line, the lower limit of the time dimension is the sudden change time of the fault signal at the measuring end, and the upper limit of the time dimension is the time corresponding to l/2v after the sudden change of the fault signal; the lower limit of the line length dimension of the second-stage distance measurement function is the line midpoint, the upper limit is the line end point, the lower limit of the time dimension is the time corresponding to l/2v after the fault signal is suddenly changed, and the upper limit is the time corresponding to l/v after the fault signal is suddenly changed.
8. An earth electrode line fault location system, comprising:
the pulse signal generating module is used for injecting a pulse signal into the line;
the electric signal acquisition module is used for acquiring and storing data;
the numerical value calculation module is used for calculating the energy of the virtual matrix and the virtual fault point;
and the fault distance measurement module is used for constructing a piecewise function and carrying out fault distance measurement by using the piecewise function mutation point to obtain a fault distance measurement result.
9. The earth electrode line fault ranging system of claim 8, wherein the pulse signal generating module comprises:
a pulse signal type selection unit for selecting the type of the injection pulse signal;
a pulse signal width selection unit for selecting a width of the injection pulse signal;
a pulse signal interval selection unit for selecting an interval of injecting a pulse signal;
and the pulse signal amplitude selecting unit is used for selecting the amplitude of the injection pulse signal.
10. The earth electrode line fault ranging system of claim 8, wherein the electrical signal acquisition module comprises:
the data acquisition unit is used for acquiring analog signals output by the secondary side of the mutual inductor;
the analog-to-digital conversion unit is used for converting the analog signal into a digital signal;
and the protection starting unit is used for judging whether the digital signal is greater than a set starting threshold value or not, and if so, reading starting time and storing data.
11. The earth electrode line fault ranging system of claim 8, wherein the numerical calculation module comprises:
the line-mode conversion unit is used for calculating the line-mode component of the voltage traveling wave at the measuring end;
the parameter setting unit is used for setting the step length of the virtual fault point and the length of the grounding electrode circuit;
and the numerical value calculating unit is used for calculating the virtual matrix and the fault distance measuring piecewise function.
12. The earth electrode line fault ranging system of claim 8, wherein the fault ranging module specifically comprises:
a distance measuring unit for measuring a distance corresponding to a maximum break point of the piecewise function;
and the polarity judging unit is used for judging the polarity of the maximum mutation point of the piecewise function.
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