CN115902530A - Earth electrode line fault distance measurement method and system - Google Patents

Abstract

The invention relates to a grounding electrode line fault distance measurement method and system, and belongs to the technical field of electric power system relay protection. In the present invention, the signal generator is used to inject pulse signals into the ground electrode line, and the mathematical expression of the traveling wave head is derived according to the traveling wave grid diagram, and the virtual fault points are set within the full line length and a virtual matrix is constructed to calculate the energy of the virtual fault points. The fault distance can be determined according to the maximum value of energy and the polarity of this value. The present invention performs fault distance measurement on DC grounding pole lines. Compared with the prior art, the present invention does not need to identify the nature of the second wave head, and has high reliability.

Description

A method and system for measuring fault distance of grounding electrode line

Technical Field

The invention relates to a grounding electrode line fault distance measurement method and system, belonging to the technical field of power system relay protection.

Background Art

The grounding electrode system is a unique and indispensable component of the ultra-high voltage direct current transmission system. It consists of a grounding electrode line and a grounding electrode site. The grounding electrode line usually uses parallel overhead lines. In order to prevent the grounding electrode from interfering with the AC side system, the grounding point of the grounding electrode site is generally tens or even more than one hundred kilometers away from the converter station. The main function of the grounding electrode line is to provide a path for the DC current. Its failure will directly affect the normal operation of the DC transmission system. When a fault occurs in the grounding electrode line, since the DC arc does not have a natural zero crossing point, it is not easy to extinguish. The DC system needs to be shut down to extinguish the arc. Therefore, it is a key technology to quickly determine the fault location and eliminate the fault to ensure the safe and stable operation of the DC transmission system. However, under the condition of bipolar symmetrical operation of the DC system, the unbalanced current in the grounding electrode line and the system neutral point potential are very small, and the grounding electrode site resistance is also very small. Therefore, once a fault occurs in the grounding electrode line, its fault additional component and fault characteristics are very small. For this reason, the traditional online passive fault detection and positioning technology and device are difficult to start, and the method is no longer applicable.

Summary of the invention

The technical problem to be solved by the present invention is to provide a grounding line fault distance measurement method and system thereof, so as to solve the problem that the traditional passive fault detection and positioning technology is difficult to start and the problem that the existing method does not accurately calibrate the arrival time of the traveling wave head, resulting in inaccurate distance measurement.

The technical solution of the present invention is: a method for measuring the fault distance of a grounding electrode line, a pulse signal generating device is connected to the measuring end of the grounding electrode line, and the pulse signal is used as a traveling wave source to inject into the grounding electrode line to achieve the fault distance measurement of the grounding electrode line under the balanced operation mode. Since the distance between the first wave head and the second wave head of the line mode voltage traveling wave is twice the fault distance, two identical line mode voltage waveforms, the first waveform moves to the right to form a first virtual matrix, and the second waveform moves to the left to form a second virtual matrix. When the first wave head of the first waveform meets the second wave head of the second waveform, the two waveforms each move 1 times the fault distance, so the ranging function forms the largest mutation point at the wave head meeting point, which is the point reflecting the fault distance information.

The specific steps are:

Step 1: Use a signal generator to inject a pulse signal into the grounding electrode line. The basis for executing this step is that in the high-voltage direct current transmission system, when the bipolar parameters are symmetrical and the bipolar is in balanced operation, the grounding electrode line is in a state of zero voltage and zero current. When a fault occurs in the grounding electrode line, the fault point cannot generate a fault traveling wave signal. Therefore, it is necessary to connect a pulse signal generator to the measuring end of the grounding electrode line, and use the pulse signal as a traveling wave source to inject the grounding electrode line to achieve the grounding electrode line fault distance measurement under the balanced operation mode. The signal generated by the signal generator is coupled to the grounding electrode line through the capacitor C. The capacitor presents low impedance to high-frequency pulse signals and high impedance to industrial frequency DC, preventing the DC of the grounding electrode lead from entering the fault monitoring device under normal working conditions, causing damage to the equipment.

Step 2: According to the response of the pulse signal at the fault point, the fault voltage traveling wave data is collected by using a signal acquisition device.

Step 2.1: Use the acquisition device at the grounding electrode line station to collect the fault traveling wave signal of the line. The implementation method of this step is that in the grounding electrode line of the actual DC transmission system, the current needs to be transmitted by an optical transformer, and its cut-off frequency is usually not more than 10kHz, which cannot be used to obtain the current traveling wave. Therefore, an overvoltage capacitor absorber is installed on the neutral bus. When a fault occurs in the line, a current traveling wave will flow through the capacitor, and a hollow coil CT is put on the overvoltage capacitor absorption branch to obtain the traveling wave.

Step 2.2: Use the Karenbauer transformation matrix to decouple the fault traveling wave signal and obtain the line mode voltage traveling wave of the grounding electrode line. The basis for executing this step is that when the grounding electrode line is fault-free, the line mode component is zero and only the zero mode component exists. However, when the grounding electrode line fails, the line mode component is no longer zero. When the zero mode component propagates to the pole address point, most of its reflected wave is absorbed by the pole address resistance. Therefore, it is not easy to detect and capture the zero mode voltage and current reflected from the pole address point at the measurement end. Secondly, the attenuation characteristics of the zero mode and line mode vary greatly with frequency. The passband of the line mode channel is very wide, and the line mode component distortion is very small, while the passband of the zero mode channel is very narrow and prone to distortion. And considering that the pulse signals injected into the two circuits of the grounding electrode are equal in size and polarity, when the grounding electrode line is not faulty, the line mode component is zero. When a fault occurs, the initial pulse signal is eliminated after the line mode transformation, thereby eliminating the influence of the initial traveling wave on the reflected wave. Therefore, the line mode component is used to measure the fault distance of the grounding electrode line.

Step 3: Perform an odd-order 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 the odd-order power transformation, and the polarity of the wave head is retained. Because the polarity of the wave head reflected from the fault point is opposite to that of the first wave head, and the polarity of the wave head reflected from the opposite bus is the same as that of the first wave head, retaining the polarity of the wave head can distinguish the nature of the second wave head.

Step 4: Set virtual fault points within the entire line length and construct a virtual matrix. The advantage of performing this step is that there is no need to calibrate the traveling wave head. It is only necessary to map the fault voltage traveling wave to each virtual fault condition to form a virtual matrix, and the actual fault distance is approximated by setting the number of virtual fault points.

Step 4.1: Set virtual fault points within the entire line length l, with a step length of akm.

Step 4.2: The fault traveling wave signal moves right by k (k=1,2,3,…,l/a) steps to form the kth row of the first virtual matrix. The fault traveling wave signal is f ₁ (t), and the first virtual matrix is:

Step 4.3: The fault traveling wave signal moves left by k (k=1,2,3,…,l/a) steps to form the kth row of the second virtual matrix. The fault traveling wave signal is f ₁ (t), and the second virtual matrix is:

Step 5: Based on the virtual matrix, calculate the energy of the virtual fault point. The advantage of performing this step is that due to the attenuation characteristics of the traveling wave, the wave head amplitude of the fault voltage traveling wave is attenuated. Therefore, when the first wave head in the first virtual matrix in Step 4 meets the second wave head in the second virtual matrix, the energy value is the largest, and the distance corresponding to this point is the real fault distance.

：Step 5.1: Calculate the product of the first virtual matrix and the second virtual matrix. The Hadamard product matrix of the two virtual matrices is

:

Step 5.2: Calculate the energy of each virtual fault point. The specific calculation method is that each row in the matrix C corresponds to a virtual fault point, and the sum of each row can be obtained to obtain the energy sum of all mutation points under each virtual fault point.

Step 6: Construct a distance measurement function and calibrate the mutation point in the distance measurement function, and use the mutation point to determine the fault distance.

Step 6.1: Construct the fault distance measurement function of the grounding electrode line. The distance measurement function is a piecewise function containing two dimensions: time and distance. The lower limit of the line length dimension of the first distance measurement function is the starting point of the line, and the upper limit is the midpoint of the line. The lower limit of the time dimension is the moment of sudden change of the fault signal at the measuring end, and the upper limit is the moment corresponding to l/2v after the sudden change of the fault signal. The lower limit of the line length dimension of the second distance measurement function is the midpoint of the line, and the upper limit is the end point of the line. The lower limit of the time dimension is the moment corresponding to l/2v after the sudden change of the fault signal, and the upper limit is the moment corresponding to l/v after the sudden change of the fault signal.

Step 6.2: calibrate the point P (x, y) with the largest mutation in the ranging function. The basis for executing this step is that when the first wave head of the first waveform meets the second wave head of the second waveform, the row corresponding to this virtual situation in the Hadamard product matrix obtains the maximum value. Due to the attenuation characteristics of the traveling wave, the Hadamard product value is relatively small when the first wave head of the first waveform meets the other wave heads of the second waveform.

Step 6.3: Determine whether the polarity of the mutation point is negative, if yes, execute Step 6.4, if no, execute Step 6.5. The basis for executing this step is that the polarity of the first wave head and the second wave head of the fault signal are opposite.

Step 6.4: The distance measurement result is x.

Step 6.5: The distance measurement result is l-x.

A grounding electrode line fault distance measurement system, characterized by comprising:

The pulse signal generating module is used to inject a pulse signal into the line.

Electrical signal acquisition module, used to collect and store data.

The numerical calculation module is used to calculate the energy of the virtual matrix and the virtual fault point.

The fault distance measurement module is used to construct a piecewise function and use the mutation points of the piecewise function to perform fault distance measurement, and then obtain the distance measurement result after the fault distance is obtained.

The grounding electrode line fault distance measurement system is characterized in that the pulse signal generating module comprises:

The pulse signal type selection unit is used to select the type of the injected pulse signal.

The pulse signal width selection unit is used to select the width of the injected pulse signal.

The pulse signal interval selection unit is used to select the interval of the injected pulse signal.

The pulse signal amplitude selection unit is used to select the amplitude of the injected pulse signal.

The grounding electrode line fault distance measurement system is characterized in that the electrical signal acquisition module comprises:

The data acquisition unit is used to collect the analog signal output from the secondary side of the transformer.

The analog-to-digital conversion unit is used to convert analog signals into digital signals.

The protection startup unit is used to determine whether the digital signal is greater than the set startup threshold. If so, the startup time is read and the data is stored.

The grounding electrode line fault distance measurement system is characterized in that the numerical calculation module includes:

The line mode conversion unit is used to calculate the line mode component of the voltage traveling wave at the measuring end.

The parameter setting unit is used to set the step size of the virtual fault point and the length of the grounding electrode line.

The numerical calculation unit is used to calculate the virtual matrix and the fault location piecewise function.

The grounding electrode line fault distance measurement system is characterized in that the fault distance measurement module specifically comprises:

The distance measurement unit is used to measure the distance corresponding to the largest mutation point of the piecewise function.

The polarity judgment unit is used to judge the polarity of the maximum mutation point of the piecewise function.

The beneficial effects of the present invention are:

1. The present invention breaks through the bottleneck of calibrating the arrival time of traveling waves in the time domain, and can easily realize the automatic single-ended traveling wave ranging of the grounding electrode line.

2. The present invention does not need to set a set value, thereby avoiding the ranging error caused by the set value.

3. The present invention does not require manual analysis of reflected waves at the fault point, thereby improving the efficiency and accuracy of fault distance measurement.

4. The distance measurement accuracy of the present invention is not affected by fault distance, transition resistance and noise, and has good robustness.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a topological diagram of a simulation model of the present invention;

FIG2 is a schematic diagram of a signal generator injecting a signal into a ground electrode in Step 1 of the present invention;

FIG3 is a schematic diagram of propagation of the response of the injected signal at the fault point in Step 2 of the present invention;

FIG4 is a schematic diagram of virtual fault point energy calculation in Step 5 of the present invention;

FIG5 is a diagram showing the first segment of the ranging function result of Example 1 of the present invention;

FIG6 is a diagram showing the result of the second segment ranging function of Embodiment 1 of the present invention;

FIG7 is a system block diagram of Embodiment 1 of the present invention;

FIG8 is a diagram showing the first segment ranging function result of Embodiment 2 of the present invention;

FIG. 9 is a diagram showing the result of the second segment ranging function of Embodiment 2 of the present invention.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

Embodiment 1: Simulation model system of high-voltage direct current transmission system with grounding electrode line is shown in Figure 1. The whole line is 80km long. The grounding electrode line adopts double-circuit overhead line on the same tower and is grounded through a resistor with very small resistance at the pole point, generally not exceeding 0.5Ω. The fault point is set on the grounding electrode line 14km away from the measuring point. The fault type is non-metallic grounding fault, the transition resistance is 1Ω, and the sampling rate is 1MHz.

The specific steps are:

Step 1: Use a signal generator to inject a pulse signal into the grounding electrode line. In this embodiment, the injected signal 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.

Step 2: According to the response of the pulse signal at the fault point, the fault voltage traveling wave data is collected by using a signal acquisition device.

Step 2.1: Use the acquisition device at the grounding electrode line station to collect the fault traveling wave signal of the line.

Step 2.2: Use the Karenbauer transformation matrix to decouple the fault traveling wave signal and obtain the grounding line line mode voltage traveling wave.

Step 3: Perform an odd-number power transformation on the fault voltage traveling wave signal. In this embodiment, the number of power transformations is 3.

Step 4: Set virtual fault points within the entire line length and construct a virtual matrix;

Step 4.1: Set a virtual fault point within the entire line length l, with a step length of akm. In this embodiment, the line length l is 80km, and the step length a is 0.1km.

Step 4.2: The fault traveling wave signal moves right by k (k=1,2,3,…,l/a) steps to form the kth row of the first virtual matrix. The fault traveling wave signal is f ₁ (t), and the first virtual matrix is:

Step 4.3: The fault traveling wave signal moves left by k (k=1,2,3,…,l/a) steps to form the kth row of the second virtual matrix. The fault traveling wave signal is f ₁ (t), and the second virtual matrix is:

Step 5: Based on the virtual matrix, calculate the energy of the virtual fault point;

：Step 5.1: Calculate the product of the first virtual matrix and the second virtual matrix. The Hadamard product matrix of the two virtual matrices is

:

Step 5.2: Calculate the energy of each virtual fault point.

Step 6: Construct a distance measurement function and calibrate the mutation point in the distance measurement function, and use the mutation point to determine the fault distance;

Step 6.1: Construct the grounding line fault distance measurement function. In this embodiment, the lower limit of the line length dimension of the first distance measurement function is 0, the upper limit is 40 km, the lower limit of the time dimension is the moment t ₀ when the fault signal at the measuring end changes, the upper limit is (t ₀ +1/2v), and the wave speed v=298km/ms; the lower limit of the line length dimension of the second distance measurement function is 40 km, the upper limit is 80 km, the lower limit of the time dimension is (t ₀ +1/2v), and the upper limit is (t ₀ +1/v).

The specific expression of the first segment ranging function is as follows:

The specific expression of the second segment ranging function is as follows:

Step 6.2: Determine the point P (x, y) with the largest mutation in the ranging function. In this embodiment, the distance corresponding to the largest mutation point in the first segment of the ranging function is 14 km, as shown in FIG5 ; the distance corresponding to the largest mutation point in the second segment of the ranging function is 66 km, as shown in FIG6 .

Step 6.3: Determine 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, the polarity of the maximum mutation point of the first-stage ranging function is negative, and the fault distance is judged to be 14km, with no ranging error; the polarity of the maximum mutation point of the second-stage ranging function is positive, and the distance corresponding to the mutation point is 66km, and the fault distance is judged to be 80-66=14km.

Compared with the traditional single-ended traveling wave ranging method, the ranging method has higher ranging accuracy, and the comparison results are shown in Table 1.

Table 1

FIG7 is a functional block diagram of a grounding electrode line fault distance measurement system provided by the present invention, comprising:

A pulse signal generating module, used for injecting a pulse signal into the line;

Electrical signal acquisition module, used for collecting and storing data;

Numerical calculation module, used to calculate the energy of virtual matrix and virtual fault point;

The fault distance measurement module is used to construct a piecewise function and use the mutation points of the piecewise function to perform fault distance measurement, and then obtain the distance measurement result after the fault distance is obtained.

The grounding electrode line fault distance measurement system is characterized in that the pulse signal generating module comprises:

A pulse signal type selection unit, used to select the type of the injected pulse signal, and in this embodiment, a 100kHz high frequency sinusoidal signal is selected;

A pulse signal width selection unit, used to select the width of the injected pulse signal. In this embodiment, the pulse width is 16us;

A pulse signal interval selection unit, used to select the interval of the injected pulse signal, in this embodiment, the pulse interval is 1.1ms;

The pulse signal amplitude selection unit is used to select the amplitude of the injected pulse signal. In this embodiment, the pulse amplitude is 48V.

The grounding electrode line fault distance measurement system is characterized in that the electrical signal acquisition module comprises:

A data acquisition unit, used for collecting analog signals output from the secondary side of the transformer;

An analog-to-digital conversion unit, used for converting an analog signal into a digital signal;

The protection startup unit is used to determine whether the digital signal is greater than the set startup threshold. If so, the startup time is read and the data is stored.

The grounding electrode line fault distance measurement system is characterized in that the numerical calculation module includes:

A line mode conversion unit, used for calculating the line mode component of the voltage traveling wave at the measuring end;

A parameter setting unit, used to set the step size of the virtual fault point and the length of the grounding electrode line. In this embodiment, the step size of the virtual fault point is 0.1 km, and the length of the grounding electrode line is 80 km;

The numerical calculation unit is used to calculate the virtual matrix and the fault location piecewise function.

The grounding electrode line fault distance measurement system is characterized in that the fault distance measurement module specifically comprises:

The distance measurement unit is used to measure 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 segment of the ranging function is 14 km; the distance corresponding to the maximum mutation point in the second segment of the ranging function is 60 km.

The polarity judgment unit is used to judge 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 segment ranging function is negative, the fault distance is judged to be 14km, and there is no ranging error; if the polarity of the maximum mutation point of the second segment ranging function is positive, the distance corresponding to the mutation point is 66km, and the fault distance is judged to be 80-66=14km.

Embodiment 2: Simulation model system of high-voltage direct current transmission system with grounding electrode line is shown in Figure 1. The whole line is 80km long. The grounding electrode line adopts double-circuit overhead line on the same tower and is grounded through a resistor with very small resistance at the pole point, generally not exceeding 0.5Ω. The fault point is set on the grounding electrode line 14km away from the measuring point. The fault type is non-metallic grounding fault, the transition resistance is 1Ω, and the sampling rate is 1MHz.

The specific steps are:

Step 1: Use a signal generator to inject a pulse signal into the grounding electrode line. In this embodiment, the injected signal is a unipolar pulse signal with a pulse width of 32us, a pulse interval of 1.1ms, and a pulse amplitude of 48V.

Step 2: According to the response of the pulse signal at the fault point, the fault voltage traveling wave data is collected by using a signal acquisition device.

Step 2.1: Use the acquisition device at the grounding electrode line station to collect the fault traveling wave signal of the line.

Step 2.2: Use the Karenbauer transformation matrix to decouple the fault traveling wave signal and obtain the grounding line line mode voltage traveling wave.

Step 3: Perform an odd-number power transformation on the fault voltage traveling wave signal. In this embodiment, the number of power transformations is 3.

Step 4: Set virtual fault points within the entire line length and construct a virtual matrix;

Step 4.1: Set a virtual fault point within the entire line length l, with a step length of akm. In this embodiment, the line length l is 80km, and the step length a is 0.1km.

Step 4.2: The fault traveling wave signal moves right by k (k=1,2,3,…,l/a) steps to form the kth row of the first virtual matrix. The fault traveling wave signal is f ₁ (t), and the first virtual matrix is:

Step 4.3: The fault traveling wave signal moves left by k (k=1,2,3,…,l/a) steps to form the kth row of the second virtual matrix. The fault traveling wave signal is f ₁ (t), and the second virtual matrix is:

Step 5: Based on the virtual matrix, calculate the energy of the virtual fault point;

：Step 5.1: Calculate the product of the first virtual matrix and the second virtual matrix. The Hadamard product matrix of the two virtual matrices is

:

Step 5.2: Calculate the energy of each virtual fault point.

Step 6: Construct a distance measurement function and calibrate the mutation point in the distance measurement function, and use the mutation point to determine the fault distance;

Step 6.1: Construct the grounding line fault distance measurement function. In this embodiment, the lower limit of the line length dimension of the first distance measurement function is 0, the upper limit is 40 km, the lower limit of the time dimension is the moment t ₀ when the fault signal at the measuring end changes, the upper limit is (t ₀ +1/2v), and the wave speed v=298km/ms; the lower limit of the line length dimension of the second distance measurement function is 40 km, the upper limit is 80 km, the lower limit of the time dimension is (t ₀ +1/2v), and the upper limit is (t ₀ +1/v).

The specific expression of the first segment ranging function is as follows:

The specific expression of the second segment ranging function is as follows:

Step 6.2: Determine the point P (x, y) with the largest mutation in the ranging function. In this embodiment, the distance corresponding to the largest mutation point in the first segment of the ranging function is 35 km, as shown in FIG8 , and the distance corresponding to the largest mutation point in the second segment of the ranging function is 45 km, as shown in FIG9 .

Step 6.3: Determine 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, the polarity of the maximum mutation point of the first-stage ranging function is negative, and the fault distance is determined to be 35km, with no ranging error; the polarity of the maximum mutation point of the second-stage ranging function is positive, and the distance corresponding to the mutation point is 45km, and the fault distance is determined to be 80-45=35km.

FIG7 is a functional block diagram of a grounding electrode line fault distance measurement system provided by the present invention, comprising:

A pulse signal generating module, used for injecting a pulse signal into the line;

Electrical signal acquisition module, used for collecting and storing data;

Numerical calculation module, used to calculate the energy of virtual matrix and virtual fault point;

The fault distance measurement module is used to construct a piecewise function and use the mutation points of the piecewise function to perform fault distance measurement, and then obtain the distance measurement result after the fault distance is obtained.

The grounding electrode line fault distance measurement system is characterized in that the pulse signal generating module comprises:

A pulse signal type selection unit, used to select the type of the injected pulse signal, and in this embodiment, a unipolar pulse signal is selected;

A pulse signal width selection unit, used to select the width of the injected pulse signal. In this embodiment, the pulse width is 32us;

A pulse signal interval selection unit, used to select the interval of the injected pulse signal, in this embodiment, the pulse interval is 1.1ms;

The pulse signal amplitude selection unit is used to select the amplitude of the injected pulse signal. In this embodiment, the pulse amplitude is 48V.

The grounding electrode line fault distance measurement system is characterized in that the electrical signal acquisition module comprises:

A data acquisition unit, used for collecting analog signals output from the secondary side of the transformer;

An analog-to-digital conversion unit, used for converting an analog signal into a digital signal;

The protection startup unit is used to determine whether the digital signal is greater than the set startup threshold. If so, the startup time is read and the data is stored.

The grounding electrode line fault distance measurement system is characterized in that the numerical calculation module includes:

A line mode conversion unit, used for calculating the line mode component of the voltage traveling wave at the measuring end;

A parameter setting unit, used to set the step size of the virtual fault point and the length of the grounding electrode line. In this embodiment, the step size of the virtual fault point is 0.1 km, and the length of the grounding electrode line is 80 km;

The numerical calculation unit is used to calculate the virtual matrix and the fault location piecewise function.

The grounding electrode line fault distance measurement system is characterized in that the fault distance measurement module specifically comprises:

The distance measuring unit is used to measure 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 segment of the distance measurement function is 35 km, and the distance corresponding to the maximum mutation point in the second segment of the distance measurement function is 45 km.

The polarity judgment unit is used to judge 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 segment ranging function is negative, the fault distance is judged to be 35km, and there is no ranging error; if the polarity of the maximum mutation point of the second segment ranging function is positive, the distance corresponding to the mutation point is 45km, and the fault distance is judged to be 80-45=35km.

Verification has shown that the grounding electrode line fault distance measurement method and system described in the present invention have high reliability.

The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims (12)

1. A method for measuring the fault location of a grounding electrode line, characterized in that: Step 1: Use a signal generator to inject a pulse signal into the grounding electrode line; Step 2: According to the response of the pulse signal at the fault point, the fault voltage traveling wave data is collected by using a signal acquisition device; Step 3: Perform odd-order power transformation on the fault voltage traveling wave signal; Step 4: Set virtual fault points within the entire line length and construct a virtual matrix; Step 5: Based on the virtual matrix, calculate the energy of the virtual fault point; Step 6: Construct a distance measurement function and calibrate the mutation point in the distance measurement function, and use the mutation point to determine the fault distance. 2. The grounding line fault distance measurement method according to claim 1 is characterized in that: in the Step 1, the injected pulse signal is a unipolar rectangular pulse signal or a high-frequency sinusoidal pulse signal. 3. The grounding line fault distance measurement method according to claim 1, characterized in that the step 2 is specifically: Step 2.1: Use the acquisition device at the grounding electrode line station to collect the fault traveling wave signal of the line; Step 2.2: Use the Karenbauer transformation matrix to decouple the fault traveling wave signal and obtain the grounding line line mode voltage traveling wave. 4. The grounding line fault distance measurement method according to claim 1, characterized in that the step 4 is specifically: Step 4.1: Set a virtual fault point within the entire line length l, with a step length of akm; Step 4.2: The fault traveling wave signal moves right by k steps, k=1,2,3,…,l/a, to form the kth row of the first virtual matrix; Step 4.3: The fault traveling wave signal moves left by k steps, k = 1, 2, 3, …, l/a, to form the kth row of the second virtual matrix. 5. The grounding line fault distance measurement method according to claim 1, characterized in that the step 5 is specifically: Step 5.1: Calculate the product of the first virtual matrix and the second virtual matrix; Step 5.2: Calculate the energy of each virtual fault point. 6. The grounding electrode line fault distance measurement method according to claim 1, characterized in that the step 6 is specifically: Step 6.1: Construct the grounding line fault location function; Step 6.2: calibrate the point P (x, y) with the largest mutation in the ranging function; Step 6.3: Determine whether the polarity of the mutation point is negative, if so, execute Step 6.4, if not, execute Step 6.5; Step 6.4: The distance measurement result is x; Step 6.5: The distance measurement result is l-x. 7. The grounding electrode line fault distance measurement method according to claim 6, characterized in that the construction of the grounding electrode fault distance measurement function is specifically: The ranging function is a piecewise function that contains two dimensions, time and distance. The lower limit of the line length dimension of the first ranging function is the starting point of the line, and the upper limit is the midpoint of the line. The lower limit of the time dimension is the moment when the fault signal at the measuring end suddenly changes, and the upper limit is the moment corresponding to l/2v after the fault signal suddenly changes. The lower limit of the line length dimension of the second ranging function is the midpoint of the line, and the upper limit is the end point of the line. The lower limit of the time dimension is the moment corresponding to l/2v after the fault signal suddenly changes, and the upper limit is the moment corresponding to l/v after the fault signal suddenly changes. 8. A grounding electrode line fault distance measurement system, characterized by comprising: A pulse signal generating module, used for injecting a pulse signal into the line; Electrical signal acquisition module, used for collecting and storing data; Numerical calculation module, used to calculate the energy of virtual matrix and virtual fault point; The fault distance measurement module is used to construct a piecewise function and use the mutation points of the piecewise function to perform fault distance measurement, and then obtain the distance measurement result after the fault distance is obtained. 9. The grounding electrode line fault distance measurement system according to claim 8, characterized in that the pulse signal generating module comprises: A pulse signal type selection unit, used for selecting the type of injected pulse signal; A pulse signal width selection unit, used for selecting the width of the injected pulse signal; A pulse signal interval selection unit, used for selecting the interval of the injected pulse signal; The pulse signal amplitude selection unit is used to select the amplitude of the injected pulse signal. 10. The grounding electrode line fault distance measurement system according to claim 8, characterized in that the electrical signal acquisition module comprises: A data acquisition unit, used for collecting analog signals output from the secondary side of the transformer; An analog-to-digital conversion unit, used for converting an analog signal into a digital signal; The protection startup unit is used to determine whether the digital signal is greater than the set startup threshold. If so, the startup time is read and the data is stored. 11. The grounding electrode line fault distance measurement system according to claim 8, characterized in that the numerical calculation module comprises: A line mode conversion unit, used for calculating the line mode component of the voltage traveling wave at the measuring end; A parameter setting unit, used to set the step length of the virtual fault point and the length of the grounding electrode line; The numerical calculation unit is used to calculate the virtual matrix and the fault location piecewise function. 12. The grounding electrode line fault distance measurement system according to claim 8, characterized in that the fault distance measurement module specifically comprises: A distance measurement unit, used to measure the distance corresponding to the maximum mutation point of the piecewise function; The polarity judgment unit is used to judge the polarity of the maximum mutation point of the piecewise function.

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