A single-ended distance measurement method and system for transmission lines based on generalized space mode current

Abstract

The present invention discloses a single-ended distance measurement method and system for transmission lines based on generalized space mode current, which belongs to the field of relay protection for power systems. The present invention constructs a generalized space mode current traveling wave by measuring the current at the fault line and the non-fault line to eliminate the influence of the reflected wave at the end of the healthy line on the reflected wave at the fault point or the reflected wave at the opposite end busbar; according to the mapping relationship between the traveling wave mutation point and the fault position, the traveling wave mutation point is deduced along the line to form a virtual fault point matrix and construct a distance measurement function, and the fault distance is obtained according to the mutation point of the distance measurement function. The present invention breaks through the bottleneck of calibrating the arrival time of the traveling wave in the time domain, and can easily realize the automated single-ended traveling wave ranging of the DC transmission line, with high ranging accuracy and strong robustness under different fault conditions.

Description

Technical Field

[0001] The invention discloses a single-end distance measurement method and system for a transmission line based on generalized space mode current, belonging to the field of relay protection of power systems. Background Art

[0002] After a transmission line fault occurs, accurately locating the fault is crucial for troubleshooting, accelerating repairs, shortening line downtime, maintaining grid strength, and reducing line congestion. Existing fault location methods are primarily divided into traveling wave methods, fault analysis methods, and natural frequency methods. The traveling wave method, unaffected by factors such as system operating mode, transition resistance, and fault type, is widely used for high-voltage, long-distance, and high-capacity transmission lines. The core of traveling wave-based fault location methods is to establish a mathematical relationship between propagation time, wave velocity, and fault distance. These methods can be categorized as single-ended or dual-ended. Traditional single-ended traveling wave methods use the time interval between the arrival of an initial fault traveling wave and its reflected wave at the same end to locate the fault. Dual-ended traveling wave methods use the time difference between the first wave heads of the fault traveling wave arriving at both ends of the line to locate the fault. Single-ended traveling wave ranging, owing to its advantages of not requiring dual-end time synchronization and communication, has attracted widespread attention. As the scale of the power grid becomes larger and more complex, the proportion of renewable energy power generation connected to AC / DC hybrid and inverters increases, the system's rotational inertia and anti-interference capability decrease, and the grid's flexibility resources become scarce. This puts higher demands on the accuracy and effectiveness of line fault location. It is urgent to study a more reliable and more targeted single-ended traveling wave fault location algorithm for engineering line inspections.

[0003] Currently, most studies have only utilized the one-dimensional time information of the fault traveling wave arriving at the measurement end. When eliminating the reflected wave at the end of the healthy line at the measurement end, it is often necessary to know the entire length of the healthy line or use the fault information of other lines. When detecting and identifying the reflected wave at the fault point (or the reflected wave from the opposite bus), it is necessary to introduce high-performance signal processing methods. Summary of the Invention

[0004] In light of the above, the present invention proposes a single-ended distance measurement method and system for transmission lines based on generalized spatial modulus current. First, the generalized spatial modulus is obtained using the current traveling waves of the fault line and the non-fault line. Second, the mapping relationship between the generalized spatial modulus current traveling wave mutation points and the fault location is analyzed. Finally, the current traveling wave is forward and backward deduced along the line to construct a ranging function, and the fault distance is determined based on its mutation points. This invention overcomes the bottleneck of calibrating the arrival time of traveling waves in the time domain, easily realizing automated single-ended traveling wave ranging for DC transmission lines, with high ranging accuracy and strong robustness under different fault conditions.

[0005] The technical solution of this invention is a single-ended transmission line distance measurement method and system based on generalized spatial mode current. This method uses generalized spatial mode current to perform group comparisons of the amplitude and polarity of wave heads, eliminating the influence of reflected waves at the end of healthy lines while enhancing the amplitudes of the initial traveling wave head and the reflected wave head at the fault point. When determining the busbar outgoing line, the nature of the second wave head is distinguished based on whether the reflected wave at the fault point has the opposite polarity to the first wave head and whether the reflected wave at the end busbar has the same polarity as the first wave head. This distance measurement method eliminates the need to calibrate the arrival time of traveling waves in the time domain, making it easy to implement automated single-ended distance measurement for transmission lines.

[0006] The specific steps are:

[0007] Step 1: Use the signal acquisition device to collect the fault current traveling waves at the fault line and non-fault line measurement ends;

[0008] Step 2: Calculate the generalized space modulus based on the collected fault current traveling wave and determine the wave head set that matches the generalized space modulus;

[0009] Step 3: Eliminate the current traveling wave of the reflected wave at the end of the healthy line based on the wave head set;

[0010] Step 4: Based on the eliminated wave head set, the ranging function is constructed by forward and reverse deduction of the traveling wave;

[0011] Step 5: Obtain a set of virtual fault points along the entire line based on the ranging function;

[0012] Step 6: Perform sgn function operation on the maximum value in the obtained virtual fault point set to determine the fault distance.

[0013] The Step 1 is specifically as follows:

[0014] Step 1.1: Install a traveling wave signal acquisition device at the busbar;

[0015] Step 1.2: Use the signal acquisition device to collect the fault current traveling waves at the measuring ends of the fault line and the non-fault line.

[0016] The Step 2 is specifically as follows:

[0017] Step 2.1: Calculate the generalized space modulus i j,k , the difference between the traveling waves of the same-phase currents of any two outgoing lines on the same bus is defined as the generalized spatial norm, and its expression is:

[0018]

[0019] Among them, i j 、i k are the currents on the j-th and k-th outgoing lines respectively;

[0020] Step 2.2: Assume that there are n outgoing lines on a busbar. When a line fails, the generalized spatial modulus between the line and other healthy lines is i1-i2, i1-i3, ..., i1-i n , use f to represent each set of generalized space modules s (t), where s=1,2,3,…,n-1, for any set of f s (t), the time corresponding to the positive and negative polarity wave heads is represented as a set 、 :

[0021]

[0022]

[0023] Where t is time, is the first-order derivative, is the second-order derivative;

[0024] Define the wave head set matching between n-1 groups of generalized space modes as :

[0025]

[0026] Where g s (t) is an exponential function, and the formula is:

[0027]

[0028] in, is the wave head set of each group of generalized space modes, .

[0029] The Step 3 is specifically as follows:

[0030] Step 3.1: Wave head set matching between generalized space modes and Take the intersection to get the wave head set that does not match between the generalized space modes :

[0031]

[0032] Step 3.2: Collect the obtained wave heads Eliminate;

[0033] gather The wave head in the image reflects the reflected waves at the end of each healthy line. Removing it can avoid the interference of the reflected waves at the end of the healthy line on the reflected waves at the fault point.

[0034] The Step 4 is specifically as follows:

[0035] Step 4.1: Define the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence as:

[0036]

[0037]

[0038] Where x vir is the distance step of the traveling wave sequence deduction, and the time step is x vir / v; l is the line length, v is the wave speed, g1(t - )、g2(t + ) is the defined exponential function, T represents the transposed matrix, P and Q are two n×k order matrices, and the number of deductions is n=l / x vir , the length of the traveling wave sequence k=2fl / v, f is the sampling frequency;

[0039] Step 4.2: Remember :

[0040]

[0041] Where p 1k q 1k is the product of the values of the first row and the kth column of the P and Q matrices;

[0042] Each row in the matrix R corresponds to a virtual fault point, and the ranging function f is constructed based on the generalized space mode and traveling wave deduction in the time window [t1, t2] m for:

[0043]

[0044] Where t1 and t2 are the upper and lower limits of the time window respectively. 、 is the defined exponential function, and m is the number of deductions.

[0045] The Step 5 is specifically as follows:

[0046] The set obtained based on the ranging function is defined as the set of virtual fault points along the entire line:

[0047]

[0048] Where F is the set of virtual fault points along the entire line.

[0049] The Step 6 is specifically as follows:

[0050] Step 6.1: Define the sgn function, which outputs 1 when the independent variable is greater than 0 and -1 when the independent variable is less than 0;

[0051] Step 6.2: Take the maximum value f n Perform sgn function operation on the independent variable. When the output of sgn function is 1, the fault distance x=nx vir ; When the output of the sgn function is -1, the fault distance x=l-nx vir , the maximum value is the mutation point in the set F, that is, the point reflecting the fault location.

[0052] To achieve the above objectives, the present application also proposes a single-ended distance measurement system for power transmission lines based on generalized space mode current, comprising:

[0053] Signal acquisition module, used to collect and store current traveling wave data at the measuring ends of the fault line and non-fault line;

[0054] The numerical acquisition and calculation module is used to calculate the current traveling wave data obtained to obtain the generalized spatial modulus and the wave head set matching between the generalized spatial moduli , and the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence are calculated to obtain the R matrix, and then the ranging function f is constructed. m ;

[0055] The fault location module is used to calibrate the maximum value f in the virtual fault point set F. n , and use the sgn function to judge the ranging result.

[0056] The signal acquisition module specifically includes:

[0057] A data acquisition unit, used to collect electrical analog signals at the measuring end;

[0058] The analog-to-digital conversion unit is used to convert the electrical analog signal on the secondary side of the transformer into a digital signal.

[0059] The numerical value acquisition and calculation module specifically includes:

[0060] Traveling wave deduction unit, used for forward and reverse deduction of time series;

[0061] Numerical calculation unit, used for matrix operations to construct the ranging function f m .

[0062] The fault location module specifically includes:

[0063] The mutation point detection unit is used to calibrate the maximum value f in the virtual fault point set F. n ;

[0064] A fault location determination unit is used to determine whether the fault location is within or outside the half-line length of the line according to the sgn function;

[0065] Fault distance calculation unit, used to calculate the fault distance according to the maximum value f n Determine the ranging result.

[0066] The present invention has the following beneficial technical effects:

[0067] (1) The proposed generalized spatial modulus can not only eliminate the reflected wave at the end of the sound line, but also enhance the amplitude of the available traveling wave head, providing a new idea for traveling wave ranging of transmission lines with a common busbar;

[0068] (2) Based on the mapping relationship between the mutation point of the generalized space mode current traveling wave and the fault location, the current traveling wave is forward deduced and reverse deduced along the line to construct a distance measurement function to obtain the fault distance;

[0069] (3) The present invention does not require calibration of the arrival time of the traveling wave, thus avoiding the ranging error caused by inaccurate wave head calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a topological diagram of the simulation model of the present invention;

[0071] Figure 2 is a flow chart of fault ranging of the present invention;

[0072] Figure 3 is a system block diagram of the present invention;

[0073] Figure 4 This is a diagram of the fault location result of Example 1 of the present invention;

[0074] Figure 5 This is a diagram of the fault location result of Example 2 of the present invention. DETAILED DESCRIPTION

[0075] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0076] Example 1: Flexible low-frequency power transmission simulation model system Figure 1 As shown in the figure, the low-frequency voltage level is 220 kV, and the low-frequency wind farm has a rated capacity of 200 MW, consisting of 40 5 MW permanent magnet direct-drive wind turbines. This wind farm is connected to the M3C frequency conversion station via a 35 kV / 220 kV step-up transformer and a 100 km transmission line. The transmission line uses a frequency-dependent model. Assume that a fault occurs on line I, 35.6 km from the wind farm (within half the line length).

[0077] A single-ended distance measurement method for transmission lines based on generalized space mode current, the process is as follows Figure 2 As shown, the specific steps are:

[0078] Step 1: Use the signal acquisition device to collect the fault current traveling waves at the measuring ends of the fault line and the non-fault line.

[0079] Step 1.1: Install a traveling wave signal acquisition device at the busbar;

[0080] Step 1.2: Use the signal acquisition device to collect the fault current traveling waves at the measuring ends of the fault line and the non-fault line.

[0081] Step 2: Calculate the generalized space modulus based on the collected fault current traveling wave and determine the wave head set that matches the generalized space modulus.

[0082] Step 2.1: Calculate the generalized space modulus i j,k , the difference between the traveling waves of the same-phase currents of any two outgoing lines on the same bus is defined as the generalized spatial norm, and its expression is:

[0083]

[0084] Among them, i j 、i k are the currents on the j-th and k-th outgoing lines respectively;

[0085] Step 2.2: Assume that there are n outgoing lines on a busbar. When a line fails, the generalized spatial modulus between the line and other healthy lines is i1-i2, i1-i3, ..., i1-i n , use f to represent each set of generalized space modules s (t), where s=1,2,3,…,n-1, for any set of f s (t), the time corresponding to the positive and negative polarity wave heads is represented as a set 、 :

[0086]

[0087]

[0088] Where t is time, is the first-order derivative, is the second-order derivative;

[0089] Define the wave head set matching between n-1 groups of generalized space modes as :

[0090]

[0091] Where g s (t) is an exponential function, and the formula is:

[0092]

[0093] in, is the wave head set of each group of generalized space modes, .

[0094] Step 3: Eliminate the current traveling wave of the reflected wave at the end of the healthy line based on the wave head set.

[0095] Step 3.1: Wave head set matching between generalized space modes and Take the intersection to get the wave head set that does not match between the generalized space modes :

[0096]

[0097] Step 3.2: Collect the obtained wave heads Eliminate.

[0098] Specifically, in this embodiment, the set of matching wave heads in the generalized space mode is The values are {0.009, 0.247, 0.381}, and the reflected wave at the end of the sound line has been eliminated.

[0099] Step 4: Based on the eliminated wave head set, the ranging function is constructed according to the forward and reverse deduction of the traveling wave.

[0100] Step 4.1: Define the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence as:

[0101]

[0102]

[0103] Where x vir is the distance step of the traveling wave sequence deduction, and the time step is x vir / v; l is the line length, v is the wave speed, g1(t - )、g2(t + ) is the defined exponential function, T represents the transposed matrix, P and Q are two n×k order matrices, and the number of deductions is n=l / x vir , the length of the traveling wave sequence k=2fl / v, f is the sampling frequency;

[0104] Step 4.2: Remember :

[0105]

[0106] Where p 1k q 1k is the product of the values of the first row and the kth column of the P and Q matrices;

[0107] Each row in the matrix R corresponds to a virtual fault point, and the ranging function f is constructed based on the generalized space mode and traveling wave deduction in the time window [t1, t2] m for:

[0108]

[0109] Where t1 and t2 are the upper and lower limits of the time window respectively. 、 is the defined exponential function, and m is the number of deductions.

[0110] Specifically, the cyclic left shift matrix and the cyclic right shift matrix are obtained by using the generalized space mode current traveling wave, and according to the ranging function f m The distance function along the line is calculated as follows Figure 4 shown.

[0111] Step 5: Obtain the set of virtual fault points along the entire line based on the ranging function.

[0112] Specifically, the set obtained based on the ranging function is defined as the set of virtual fault points along the entire line:

[0113]

[0114] Where F is the set of virtual fault points along the entire line.

[0115] Step 6: Perform sgn function operation on the maximum value in the obtained virtual fault point set to determine the fault distance.

[0116] Step 6.1: Define the sgn function, which outputs 1 when the independent variable is greater than 0 and -1 when the independent variable is less than 0;

[0117] Step 6.2: Take the maximum value f n Perform sgn function operation on the independent variable. When the output of sgn function is 1, the fault distance x=nx vir ; When the output of the sgn function is -1, the fault distance x=l-nx vir , the maximum value is the mutation point in set F.

[0118] Specifically, the mutation point in the set F is the point that reflects the fault location. Figure 4 As shown, there is a mutation point x in the distribution of the distance function along the line of segment I. I1 =35.6km, and the mutation point is positive; there are two mutation points x along the distribution of the distance function in section II. II1 =64.4km and x II2 =71.3km, mutation point x II1 is negative polarity, xII2 It is positive polarity.

[0119] Further, by Figure 4 As shown, in this embodiment, since there are multiple outgoing lines on the busbars at both ends of the fault line (the number of outgoing lines ≥ 3), the reflected wave at the fault point has the same polarity as the initial traveling wave, and the reflected wave at the opposite end busbar has the opposite polarity to the initial traveling wave, and x I1 +x II1 =100km=1, so the position corresponding to the positive polarity mutation point in the distribution of the distance function along the line of section I is the actual fault distance, that is, the fault distance x f =35.6km.

[0120] Figure 3 The present invention provides a single-ended distance measurement system for a power transmission line based on generalized space mode current, comprising:

[0121] Signal acquisition module, used to collect and store current traveling wave data at the measuring ends of the fault line and non-fault line;

[0122] The numerical acquisition and calculation module is used to calculate the current traveling wave data obtained to obtain the generalized spatial modulus and the wave head set matching between the generalized spatial moduli , and the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence are calculated to obtain the R matrix, and then the ranging function f is constructed. m ;

[0123] The fault location module is used to calibrate the maximum value f in the virtual fault point set F. n , and use the sgn function to judge the ranging result.

[0124] The signal acquisition module specifically includes:

[0125] A data acquisition unit, used to collect electrical analog signals at the measuring end;

[0126] The analog-to-digital conversion unit is used to convert the electrical analog signal on the secondary side of the transformer into a digital signal.

[0127] The numerical value acquisition and calculation module specifically includes:

[0128] Traveling wave deduction unit, used for forward and reverse deduction of time series;

[0129] Numerical calculation unit, used for matrix operations to construct the ranging function f m .

[0130] The fault location module specifically includes:

[0131] The mutation point detection unit is used to calibrate the maximum value f in the virtual fault point set F. n ;

[0132] A fault location determination unit is used to determine whether the fault location is within or outside the half-line length of the line according to the sgn function;

[0133] Fault distance calculation unit, used to calculate the fault distance according to the maximum value f n Determine the ranging result.

[0134] Example 2: Flexible low-frequency power transmission simulation model system Figure 1 As shown in the figure, the low-frequency voltage level is 220 kV, and the low-frequency wind farm has a rated capacity of 200 MW, consisting of 40 5 MW permanent magnet direct-drive wind turbines. This wind farm is connected to the M3C frequency conversion station via a 35 kV / 220 kV step-up transformer and a 100 km transmission line. The transmission line uses a frequency-dependent model. Assume that a fault occurs on line I, 83.67 km from the wind farm (exceeding half the line length).

[0135] A single-ended distance measurement method for transmission lines based on generalized space mode current, the process is as follows Figure 2 As shown, the specific steps are:

[0136] Step 1: Use the signal acquisition device to collect the fault current traveling waves at the measuring ends of the fault line and the non-fault line.

[0137] Step 1.1: Install a traveling wave signal acquisition device at the busbar;

[0138] Step 1.2: Use the signal acquisition device to collect the fault current traveling waves at the measuring ends of the fault line and the non-fault line.

[0139] Step 2: Calculate the generalized space modulus based on the collected fault current traveling wave and determine the wave head set that matches the generalized space modulus.

[0140] Step 2.1: Calculate the generalized space modulus i j,k , the difference between the traveling waves of the same-phase currents of any two outgoing lines on the same bus is defined as the generalized spatial norm, and its expression is:

[0141]

[0142] Among them, i j 、i k are the currents on the j-th and k-th outgoing lines respectively;

[0143] Step 2.2: Assume that there are n outgoing lines on a busbar. When a line fails, the generalized spatial modulus between the line and other healthy lines is i1-i2, i1-i3, ..., i1-i n , use f to represent each set of generalized space modules s (t), where s=1,2,3,…,n-1, for any set of f s(t), the time corresponding to the positive and negative polarity wave heads is represented as a set 、 :

[0144]

[0145] Where t is time, is the first-order derivative, is the second-order derivative;

[0146] Define the wave head set matching between n-1 groups of generalized space modes as :

[0147]

[0148] Where g s (t) is an exponential function, and the formula is:

[0149]

[0150] in, is the wave head set of each group of generalized space modes, .

[0151] Step 3: Eliminate the current traveling wave of the reflected wave at the end of the healthy line based on the wave head set.

[0152] Step 3.1: Wave head set matching between generalized space modes and Take the intersection to get the wave head set that does not match between the generalized space modes :

[0153]

[0154] Step 3.2: Collect the obtained wave heads Eliminate.

[0155] Step 4: Based on the eliminated wave head set, the ranging function is constructed according to the forward and reverse deduction of the traveling wave.

[0156] Step 4.1: Define the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence as:

[0157]

[0158]

[0159] Where x vir is the distance step of the traveling wave sequence deduction, and the time step is x vir / v; l is the line length, v is the wave speed, g1(t - )、g2(t + ) is the defined exponential function, T represents the transposed matrix, P and Q are two n×k order matrices, and the number of deductions is n=l / x vir , the length of the traveling wave sequence k=2fl / v, f is the sampling frequency;

[0160] Step 4.2: Remember :

[0161]

[0162] Where p 1k q 1k is the product of the values of the first row and the kth column of the P and Q matrices;

[0163] Each row in the matrix R corresponds to a virtual fault point, and the ranging function f is constructed based on the generalized space mode and traveling wave deduction in the time window [t1, t2] m for:

[0164]

[0165] Where t1 and t2 are the upper and lower limits of the time window respectively. 、 is the defined exponential function, and m is the number of deductions.

[0166] Specifically, the cyclic left shift matrix and the cyclic right shift matrix are obtained by using the generalized space mode current traveling wave, and according to the ranging function f m The distance function along the line is calculated as follows Figure 5 shown.

[0167] Step 5: Obtain the set of virtual fault points along the entire line based on the ranging function.

[0168] Specifically, the set obtained based on the ranging function is defined as the set of virtual fault points along the entire line:

[0169]

[0170] Where F is the set of virtual fault points along the entire line.

[0171] Step 6: Perform sgn function operation on the maximum value in the obtained virtual fault point set to determine the fault distance.

[0172] Step 6.1: Define the sgn function, which outputs 1 when the independent variable is greater than 0 and -1 when the independent variable is less than 0;

[0173] Step 6.2: Take the maximum value f nPerform sgn function operation on the independent variable. When the output of sgn function is 1, the fault distance x=nx vir ; When the output of the sgn function is -1, the fault distance x=l-nx vir , the maximum value is the mutation point in set F.

[0174] Specifically, the mutation point in the set F is the point that reflects the fault location. Figure 5 As shown, there are two mutation points x in the distribution of the distance function of segment I. I1 =16.3km, x I2 =32.6km, and both mutation points are negative polarity; there is a mutation point x in the distribution of the distance function along the line of section II. II1 =83.8km, and it is positive polarity.

[0175] Further, by Figure 5 As shown in the figure, the position corresponding to the positive polarity mutation point in the distribution of the distance function along the line of section II is the actual fault distance, that is, the fault distance x f =83.8km.

[0176] Figure 3 The present invention provides a single-ended distance measurement system for a transmission line based on generalized space mode current, comprising:

[0177] Signal acquisition module, used to collect and store current traveling wave data at the measuring ends of the fault line and non-fault line;

[0178] The numerical acquisition and calculation module is used to calculate the current traveling wave data obtained to obtain the generalized spatial modulus and the wave head set matching between the generalized spatial moduli , and the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence are calculated to obtain the R matrix, and then the ranging function f is constructed. m ;

[0179] The fault location module is used to calibrate the maximum value f in the virtual fault point set F. n , and use the sgn function to judge the ranging results.

[0180] The signal acquisition module specifically includes:

[0181] A data acquisition unit, used to collect electrical analog signals at the measuring end;

[0182] The analog-to-digital conversion unit is used to convert the electrical analog signal on the secondary side of the transformer into a digital signal.

[0183] The numerical value acquisition and calculation module specifically includes:

[0184] Traveling wave deduction unit, used for forward and reverse deduction of time series;

[0185] Numerical calculation unit, used for matrix operations to construct the ranging function f m .

[0186] The fault location module specifically includes:

[0187] The mutation point detection unit is used to calibrate the maximum value f in the virtual fault point set F. n ;

[0188] A fault location determination unit is used to determine whether the fault location is within or outside the half-line length of the line according to the sgn function;

[0189] Fault distance calculation unit, used to calculate the fault distance according to the maximum value f n Determine the ranging result.

[0190] The above embodiments show that no matter the fault occurs within or outside the half line length, the present invention can accurately locate the fault.

[0191] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A single-ended distance measurement method for transmission lines based on generalized space mode current, characterized by: Step 1: Use the signal acquisition device to collect the fault current traveling waves at the fault line and non-fault line measurement ends; Step 2: Calculate the generalized space modulus based on the collected fault current traveling wave and determine the wave head set that matches the generalized space modulus; Step 3: Eliminate the current traveling wave of the reflected wave at the end of the healthy line based on the wave head set; Step 4: Based on the eliminated wave head set, the ranging function is constructed by forward and reverse deduction of the traveling wave; Step 5: Obtain a set of virtual fault points along the entire line based on the ranging function; Step 6: Perform sgn function operation on the maximum value in the obtained virtual fault point set to determine the fault distance; The Step 2 is specifically as follows: Step 2.1: Calculate the generalized space modulus i j,k , the difference between the traveling waves of the same-phase currents of any two outgoing lines on the same bus is defined as the generalized spatial norm, and its expression is: ； Among them, i j 、i k are the currents on the j-th and k-th outgoing lines respectively; Step 2.2: Assume that there are n outgoing lines on a busbar. When a line fails, the generalized spatial modulus between the line and other healthy lines is i1-i2, i1-i3, ..., i1-i n , use f to represent each set of generalized space modules s (t), where s=1,2,3,…,n-1, for any set of f s (t), the time corresponding to the positive and negative polarity wave heads is represented as a set 、 : ； ； Where t is time, is the first-order derivative, is the second-order derivative; Define the wave head set matching between n-1 groups of generalized space modes as : ； Where g s (t) is an exponential function, and the formula is: ； in, is the wave head set of each group of generalized space modes, ; The Step 4 is specifically as follows: Step 4.1: Define the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence as: ； ； Where x vir is the distance step of the traveling wave sequence deduction, and the time step is x vir / v; l is the line length, v is the wave speed, g1(t - )、g2(t + ) is the defined exponential function, T represents the transposed matrix, P and Q are two n×k order matrices, and the number of deductions is n=l / x vir , the length of the traveling wave sequence k=2fl / v, f is the sampling frequency; Step 4.2: Remember : ； Where p 1k q 1k is the product of the values of the first row and the kth column of the P and Q matrices; Each row in the matrix R corresponds to a virtual fault point, and the ranging function f is constructed based on the generalized space mode and traveling wave deduction in the time window [t1, t2] m for: ； Where t1 and t2 are the upper and lower limits of the time window respectively. 、 is the defined exponential function, and m is the number of deductions.

2. The single-ended distance measurement method for a transmission line based on generalized space mode current according to claim 1, characterized in that: The Step 1 is specifically as follows: Step 1.1: Install a traveling wave signal acquisition device at the busbar; Step 1.2: Use the signal acquisition device to collect the fault current traveling waves at the measuring ends of the fault line and the non-fault line.

3. The single-ended distance measurement method for a transmission line based on generalized space mode current according to claim 1, characterized in that: The Step 3 is specifically as follows: Step 3.1: Wave head set matching between generalized space modes and Take the intersection to get the wave head set that does not match between the generalized space modes : ； Step 3.2: Collect the obtained wave heads Eliminate.

4. The single-ended distance measurement method for a transmission line based on generalized space mode current according to claim 1, characterized in that: The Step 5 is specifically as follows: The set obtained based on the ranging function is defined as the set of virtual fault points along the entire line: ； Where F is the set of virtual fault points along the entire line.

5. The single-ended distance measurement method for a transmission line based on generalized space mode current according to claim 1, characterized in that: The Step 6 is specifically as follows: Step 6.1: Define the sgn function, which outputs 1 when the independent variable is greater than 0 and -1 when the independent variable is less than 0; Step 6.2: Take the maximum value f n Perform sgn function operation on the independent variable. When the output of sgn function is 1, the fault distance x=nx vir ; When the output of the sgn function is -1, the fault distance x=l-nx vir , the maximum value is the mutation point in set F.

6. A system for implementing the single-ended distance measurement method for transmission lines based on generalized space mode current according to claim 1, characterized in that: include: Signal acquisition module, used to collect and store current traveling wave data at the measuring ends of the fault line and non-fault line; The numerical acquisition and calculation module is used to calculate the current traveling wave data obtained to obtain the generalized spatial modulus and the wave head set matching between the generalized spatial moduli , and the forward deduction matrix P of the original current traveling wave sequence and the reverse deduction matrix Q of the original current traveling wave sequence are calculated to obtain the R matrix, and then the ranging function f is constructed. m ; The fault location module is used to calibrate the maximum value f in the virtual fault point set F. n , and use the sgn function to judge the ranging results.

7. The system according to claim 6, characterized in that The signal acquisition module specifically includes: A data acquisition unit, used to collect electrical analog signals at the measuring end; The analog-to-digital conversion unit is used to convert the electrical analog signal on the secondary side of the transformer into a digital signal.

8. The system according to claim 6, wherein: The numerical value acquisition and calculation module specifically includes: Traveling wave deduction unit, used for forward and reverse deduction of time series; Numerical calculation unit, used for matrix operations to construct the ranging function f m .

9. The system according to claim 6, wherein: The fault location module specifically includes: The mutation point detection unit is used to calibrate the maximum value f in the virtual fault point set F. n ; A fault location determination unit is used to determine whether the fault location is within or outside the half-line length of the line according to the sgn function; Fault distance calculation unit, used to calculate the fault distance according to the maximum value f n Determine the ranging result.

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