A method, device and equipment for identifying faults in a power transmission system

Abstract

A method, device and equipment for identifying faults in a power transmission system. When a fault occurs, a relay protection device or a synchronous phasor unit is used to obtain three-phase voltage phasors and three-phase current phasors at the left end bus of the line and three-phase voltage phasors and three-phase current phasors at the right end bus at time k, and then obtain an initial state variable set of the fault distance of the power transmission system line equivalent model; based on the initial state variable set, a gain matrix and a state variable correction value set of the power transmission system at time k are forward calculated from the fault time point; based on the gain matrix and the state variable correction value ... max Starting from the time point k, the smoothed value set of the state variables is calculated backward; the average value of the smoothed value set of the state variables at the time of the fault is calculated as the fault distance; the three-phase currents on both sides of the fault point are calculated according to the fault distance, and the fault type is determined according to the relationship between the three-phase currents, thereby realizing accurate detection of the fault type of the transmission system.

Description

Technical Field

[0001] The present invention relates to the field of power system fault analysis and diagnosis, and in particular to a method, device and equipment for identifying power transmission system faults based on a collective Kalman smoother. Background Art

[0002] Transmission line fault location is to determine the fault location through certain methods when a fault occurs in the line, while fault diagnosis is to determine the type of fault through the collected data. By determining the fault location and type, the time for maintenance personnel to manually patrol the line to determine and clear the fault can be shortened, thereby effectively improving the efficiency of power system maintenance and reducing the loss of power outages caused by faults.

[0003] By establishing the state equation and measurement equation of the transmission line after the fault, combined with the state estimation algorithm, the optimal estimate of the fault distance can be obtained, which is one of the research hotspots of fault location methods in recent years. Some literatures use the estimation method of Taylor-Kalman-Fourier filter, the least squares estimation method based on the multi-zone π-type equivalent model, the line head estimation method based on the adaptive extended Kalman filter, and the ensemble Kalman filter method through two-step estimation. These methods are all more dependent on the size of the data sample and only use the Kalman filter to forward calculate the fault distance. Considering that there is only a time window of tens of milliseconds from the fault to the protection action and the data samples are limited, the effect of the existing methods may be limited, and it is difficult to accurately identify the fault type of the transmission system. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a method, apparatus and device for identifying a power transmission system fault, so as to achieve accurate identification of the type of power transmission system fault.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A method for identifying faults in a power transmission system, comprising:

[0007] When a fault occurs, the relay protection device or the synchronous phasor unit is used to obtain the three-phase voltage phasor and the three-phase current phasor at the left end bus of the line and the three-phase voltage phasor and the three-phase current phasor at the right end bus at time k, k = 1, 2, ..., k max , where k is the kth time point in the data sequence collected by the relay protection device or the synchronous phasor unit in the power transmission system, the time when the fault occurs is the time k=1, and the k max The time point is the maximum time of the data sequence collected by the relay protection device or the synchronized phasor unit, and the relay protection device or the synchronized phasor unit is a relay protection device or a synchronized phasor unit installed at the left and right busbars of the power transmission system line;

[0008] Obtaining an initial state variable set X0 of the fault distance of the transmission system line equivalent model;

[0009] Based on the initial state variable set X0, forward calculation of the transmission system gain matrix K at time k starts from the fault time point k and the state variable correction value set X k ;

[0010] Based on the gain matrix K k and the set of state variable correction values, from k max Start from the time point and calculate the smoothed value set of the state variables at time k backward

[0011] Calculate the smoothed value set of the state variables at the time of failure The average value of the fault distance

[0012] According to the fault distance Calculate the three-phase currents on both sides of the fault point and determine the fault type based on the relationship between the three-phase currents.

[0013] Optionally, in the above-mentioned power transmission system fault identification method, obtaining the initial state variable set X0 of the fault distance of the power transmission system line equivalent model includes:

[0014] Based on the formula Calculate the initial value of the fault distance Among them, the D t is the total length of the transmission system lines;

[0015] Obtain the variance P0 of the state variable determined based on prior knowledge;

[0016] from Sampling M variables x from the distribution 0.i =D 0.i (i=1,2,...,M) constitutes the initial state variable set X0={x 0.i}(i=1,2,...,M), where M is a positive integer greater than 1, D 0.i is the fault distance in the i-th variable among the sampled M variables.

[0017] Optionally, in the above-mentioned power transmission system fault identification method, the gain matrix K of the power transmission system at time k is forward calculated starting from the fault time point k ,include:

[0018] Based on the formula Starting from the fault time point, forward calculation of the transmission system gain matrix K at time k k ;

[0019] Output variable estimated value set for k time, For collection The i-th variable of ;

[0020] for The average value set, 1 1×M is a 1×M-dimensional all-1 matrix;

[0021] R is the covariance matrix of measurement noise;

[0022]

[0023] In the formula, v i ~N(0,R) is the i-th measurement noise, “~N(0,R)” means that vi satisfies the Gaussian distribution with mean 0 and covariance R; are the voltage phasors on the left and right of the fault point calculated using the estimated fault distance at time k;

[0024]

[0025]

[0026] in, is the estimated value set of state variables at time k The i-th element of You can use the formula Calculation, capital X is a set, is the estimated value set of state variables at time k The i-th element of

[0027] X k-1 ={x (k-1).i}(i=1,2,...,M) is the set of state variable correction values ​​at time k-1,

[0028] W k-1 ={w (k-1 ) .i}(i=1,2,...,M) is the process noise set at time k, w (k-1).i Obey N(0,Q) distribution;

[0029] They are the three-phase voltage phasors and three-phase current phasors at the left busbar of the line at time k respectively; are the three-phase voltage phasors and three-phase current phasors at the busbar on the right side of the line at time k; ω is the electrical angular frequency; the matrices R(l), L(l), and C(l) are the resistance matrix, inductance matrix, and capacitance matrix functions of the line length, respectively. l is any line length. For the line on the left side of the fault point, For the line on the right side of the fault point

[0030] Optionally, in the above-mentioned power transmission system fault identification method, the state variable correction value set X of the power transmission system at time k is forward calculated starting from the fault time point k ,include:

[0031] Based on the formula Starting from the fault time point, calculate the set of state variable correction values ​​X of the transmission system at time k k ;

[0032] In the formula, X k ={x k.i}(i=1,2,...,M) is the set of state variable correction values ​​at time k, x k.i =D k.i is the modified value of the i-th state variable at time k, D k.i Using the formula Calculate, x k.i =D k.i For the set X k ={x k.i The i-th variable in}

[0033] ; is the estimated value set of state variables at time k; is the set of estimated deviation values ​​of the state variables at time k;

[0034] in,

[0035] In the formula, X k-1 ={x (k-1).i}(i=1,2,...,M) is the set of state variable correction values ​​at time k-1, and when k=1, X k-1 =X0,x (k-1).i =D (k-1).i is the modified value of the i-th state variable at time k-1; W k-1 ={w (k-1 ) .i}(i=1,2,...,M) is the process noise set at time k, w (k-1).i It obeys N(0,Q) distribution, where Q is its variance.

[0036] Optionally, in the above-mentioned power transmission system fault identification method, from k max Start from the time point and calculate the smoothed value set of the state variables at time k backward include:

[0037] Based on the formula From k max Start from the time point and calculate the smoothed value set of the state variables at time k backward

[0038] In the formula, is the set of smoothed values ​​of the state variables at time k, k+1=k max hour is the set of smoothed deviation values ​​of the state variables at time k+1,

[0039] Optionally, in the above-mentioned power transmission system fault identification method, the calculation of the state variable smoothing value set The average values ​​include:

[0040] Based on the formula Calculate the state variable smoothing value set The average value of .

[0041] Optionally, in the above-mentioned power transmission system fault identification method, the fault distance Calculate the three-phase currents on both sides of the fault point, including:

[0042] Based on the formula calculate

[0043] The three-phase current phasors i on the left and right sides of the fault point l and i r ;

[0044]

[0045]

[0046]

[0047]

[0048] The rules for identifying fault types based on three-phase current are:

[0049] Determine the fault type based on the three-phase current relationship, including:

[0050] Assume j (j=a,b,c) is the fault identifier of phase j, where s j =0 means there is no fault in this phase, s j =1 indicates that the phase is faulty;

[0051] like Then suppose s j =1, where ε is the threshold value;

[0052] If a +s b +s c =3, it can be judged as a three-phase fault;

[0053] If a +s b +s c =2 and It can be judged as a two-phase phase-to-phase fault; otherwise, it is a two-phase grounding fault;

[0054] If a +s b +s c =1, it can be judged as a single-phase grounding fault.

[0055] A power transmission system fault identification device, comprising:

[0056] The data acquisition unit is used to obtain the three-phase voltage phasor and the three-phase current phasor at the left end bus of the line and the three-phase voltage phasor and the three-phase current phasor at the right end bus at time k when a fault occurs, through the relay protection device or the synchronous phasor unit, k=1,2,…,k max , where k is the kth time point in the data sequence collected by the relay protection device or the synchronous phasor unit in the power transmission system, the time when the fault occurs is the time k=1, and the k max The time point is the maximum time of the data sequence collected by the relay protection device or the synchronized phasor unit, and the relay protection device or the synchronized phasor unit is a relay protection device or a synchronized phasor unit installed at the left and right busbars of the power transmission system line;

[0057] A first calculation unit is used to obtain an initial state variable set X0 of the fault distance of the transmission system line equivalent model;

[0058] The second calculation unit is used to forward calculate the gain matrix K of the power transmission system at time k starting from the fault time point based on the initial state variable set X0. k and the state variable correction value set X k ;

[0059] The third calculation unit is used to calculate the gain matrix K based on the k and the set of state variable correction values, from k max Start from the time point and calculate the smoothed value set of the state variables at time k backward

[0060] The fourth calculation unit is used to calculate the smoothed value set of the state variables at the time of the fault The average value of the fault distance

[0061] A fault analysis unit is used to analyze the fault distance according to the Calculate the three-phase currents on both sides of the fault point and determine the fault type based on the relationship between the three-phase currents.

[0062] A power transmission system fault identification device, comprising:

[0063] The memory is used to store programs;

[0064] The processor is used to execute the program to implement each step of the power transmission system fault identification method as described in any one of the above items.

[0065] Based on the above technical solution, the above solution provided by the embodiment of the present invention is a method, device and equipment for identifying faults in a power transmission system. When a fault occurs, a relay protection device or a synchronous phasor unit is used to obtain the three-phase voltage phasor, the three-phase current phasor at the left end bus of the line and the three-phase voltage phasor and the three-phase current phasor at the right end bus at time k, and then obtain the initial state variable set of the fault distance of the transmission system line equivalent model; based on the initial state variable set, the gain matrix and the state variable correction value set of the transmission system at time k are forward calculated starting from the fault time point; based on the gain matrix and the state variable correction value set, from k max Starting from the time point k, the smoothed value set of the state variables is calculated backward; the average value of the smoothed value set of the state variables at the time of the fault is calculated as the fault distance; the three-phase currents on both sides of the fault point are calculated according to the fault distance, and the fault type is determined according to the relationship between the three-phase currents, thereby realizing accurate detection of the fault type of the transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0067] Figure 1 A schematic diagram of a flow chart of a power transmission system fault identification method disclosed in an embodiment of the present application;

[0068] Figure 2 A schematic diagram of the structure of a power transmission system fault identification device disclosed in an embodiment of the present application;

[0069] Figure 3 This is a schematic diagram of the structure of a power transmission system fault identification device disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] The ensemble Kalman smoother is a method that uses data forward calculation and backward smoothing. It can make full use of previous and subsequent data to estimate the fault distance at the current moment, thereby overcoming the problem of limited data samples after the fault and obtaining higher estimation accuracy.

[0072] The present invention proposes a transmission system fault identification method based on a collective Kalman smoother, which can make full use of the limited data in the window, improve the accuracy of the fault estimation distance through forward filtering and backward smoothing, and then identify the fault type, which can effectively overcome the problem of reduced estimation accuracy caused by limited line data collection after the fault.

[0073] In the technical solution disclosed in the embodiment of the present application, some known data of the power transmission system need to be collected in advance, and these known data may include:

[0074] The total length of the line Dt; the positive-sequence resistance Rp0, positive-sequence inductance Lp0 and positive-sequence capacitance Cp0 of the line per unit length, the zero-sequence resistance Rz0, zero-sequence inductance Lz0 and zero-sequence capacitance Cz0 of the line per unit length; the state variable variance P0; the system error variance Q; the covariance matrix R of the measurement noise; the number of elements M in the state variable set.

[0075] When a power transmission system fault is detected, the power transmission system fault identification method disclosed in the embodiment of the present application is executed, see Figure 1 , the method may specifically include:

[0076] Step S101: using a relay protection device or a synchronous phasor unit to obtain three-phase voltage phasors and three-phase current phasors at the left end bus of the line and three-phase voltage phasors and three-phase current phasors at the right end bus at time k;

[0077] When a fault occurs, taking the fault instant as moment 1, the relay protection devices or synchronous phasor units installed at the left and right busbars of the line obtain the k-th moment (k=1, 2, …, k max ) Three-phase voltage phasor at the left end of the line Three-phase current phasors Three-phase voltage phasor at the right bus Three-phase current phasors The k max The maximum moment.

[0078] Step S102: obtaining an initial state variable set X0 of the fault distance of the transmission system line equivalent model;

[0079] In this solution, the initial state variable set is X0, which is obtained by the following method:

[0080] The total length of the line D t Half of the value is taken as the initial estimated value of the distance between the fault point and the left busbar (hereinafter referred to as the fault distance) Right now The variance P0 of the state variable is determined based on prior knowledge, thus forming a normal distribution from Sampling M variables x from the distribution 0.i =D 0.i (i=1,2,...,M) constitutes a set X0={x 0.i}(i=1,2,...,M), where M is a positive integer greater than 1, where D 0.i is the fault distance in the i-th variable among the sampled M variables.

[0081] Step S103: Calculate the gain matrix at time k;

[0082] In this step, based on the initial state variable set X0, the gain matrix K of the power transmission system at time k is forward calculated starting from the fault time point k ;

[0083] The gain matrix K at time k k The calculation formula is:

[0084]

[0085] Where k = 1, 2, ..., k max is the kth time point in the data sequence collected by the relay protection device or the synchronous phasor unit, k max is the maximum moment of the data sequence; Output variable estimated value set for k time, For collection The i-th variable of ; for The average value set, 1 1×M is a 1×M-dimensional all-one matrix; R is the covariance matrix of the measurement noise. The output variable refers to the output quantity that can be observed / measured by the system or method (in this invention, it refers to the three-phase voltage difference on the left and right sides of the fault point). The various X sets generated in the intermediate process are unobservable and can only be used as state variables, not output variables. The estimated value set of this variable is The estimate (or "guess") from this method can also come from the real measurement (the real measurement result in this method is always 0, so it is not reflected). The difference between the estimate and the measurement is used to form the correction gain K, and K is used to correct the state variable set X at the next moment, so that the state variable set X at the next moment is It is closer to the real measurement (i.e. 0), and finally the unity of the two is achieved. At this time, the error between the estimated value of the observable output variable and the actual value is very small or there is no error, which means that there is no error between the intermediate variable (various X sets) and the true value, that is, an accurate estimation of the fault location is achieved.

[0086] Said The specific calculation formula is:

[0087] In the formula, v i ~N(0,R) is the i-th measurement noise; They are respectively the voltage phasors on the left and right of the fault point calculated using the estimated fault distance at time k:

[0088]

[0089]

[0090] in, is the estimated value set of state variables at time k The i-th element of They are the three-phase voltage phasors and three-phase current phasors at the left busbar of the line at time k, which can be measured by a relay protection device or a synchronous phasor unit; are the three-phase voltage phasors and three-phase current phasors at the busbar on the right side of the line at time k, which can be measured by a relay protection device or a synchronous phasor unit; ω is the electrical angular frequency; the matrices R(l), L(l), and C(l) are the resistance matrix, inductance matrix, and capacitance matrix functions of the line length, respectively. The matrices R(l), L(l), and C(l) can be known quantities, l is an arbitrary line length, and for the line on the left side of the fault point For the line on the right side of the fault point In this scheme, the specific calculation formula of R(l), L(l) and C(l) can be:

[0091]

[0092]

[0093]

[0094] in,

[0095] R s (l) = [2fRp (l)R p0 +f Rz (l)R z0 ] / 3, R m (l)=[f Rz (l)R z0 -f Rp (l)R p0 ] / 3,

[0096] L s (l) = [2f Lp (l)L p0 +f Lz (l)L z0 ] / 3, L m (l)=[f Lz (l)L z0 -f Lp (l)L p0 ] / 3,

[0097] C p (l) = f Cp (l)C p0 ,

[0098] In the formula, R p0 , L p0 , C p0 are the positive sequence resistance, inductance and capacitance per unit length provided by the manufacturer or marked on the line, R z0 , L z0 , C z0 are the zero-sequence resistance, inductance and capacitance per unit length provided by the manufacturer or marked on the line; function f Rp (l), f Lp (l), f Cp (l) are the correction functions of the positive sequence resistance, inductance and capacitance per unit length of the line, respectively, and f Rz (l), f Lz (l), f Cz (l) are the correction functions of zero-sequence resistance, inductance and capacitance per unit length of the line respectively:

[0099] f Rp (l) = Re[Z cp sinh(γ p l)] / l,f Lp (l) = Im[Z cp sinh(γ p l)] / (ωl)

[0100] f Cp (l) = Im[2tanh(γ p l / 2) / Zcp ] / (ωl),f Rz (l) = Re[Z cz sinh(γ z l)] / l

[0101] f Lz (l) = Im[Z cz sinh(γ z l)] / (ωl), f Cz (l) = Im[2tanh(γ z l / 2) / Z cz ] / (ωl)

[0102] Among them, Re and Im are the real and imaginary parts respectively; Z cp , γ p and Z cz , γ z They are positive sequence wave impedance, propagation coefficient and zero sequence wave impedance, propagation coefficient respectively. The specific calculation formula is as follows:

[0103]

[0104]

[0105] Step S104: Calculate the set of state variable correction values ​​at time k:

[0106] This step specifically calculates the state variable correction value set X of the power transmission system at time k from the fault time point based on the initial state variable set X0 k ;

[0107] The set of state variable correction values ​​X at time k k The calculation formula is:

[0108] In the formula, X k ={x k.i}(i=1,2,...,M) is the set of state variable correction values ​​at time k, x k.i =D k.i is the correction value of the i-th state variable at time k; is the estimated value set of state variables at time k; It is the set of estimated deviation values ​​of the state variables at time k.

[0109] and The calculation formulas are:

[0110]

[0111]

[0112] In the formula, X k-1 ={x (k-1).i}(i=1,2,...,M) is the set of state variable correction values ​​at time k-1, and when k=1, X k-1 =X0,x (k-1).i =D (k-1).i is the modified value of the i-th state variable at time k-1; W k-1 ={w (k-1).i}(i=1,2,...,M) is the process noise set at time k, w (k-1).i It obeys N(0,Q) distribution, where Q is the systematic error variance in the known data above.

[0113] Step S105: Calculate the smoothed value set of state variables at time k;

[0114] The set of smoothed values ​​of state variables at time k The calculation formula is

[0115]

[0116] In the formula, is the set of smoothed values ​​of the state variables at time k, k+1=k max hour is the set of smooth deviation values ​​of the state variables at time k+1, and its calculation formula is:

[0117]

[0118] Step S106: Calculate the smoothed value set of the state variable at the time of the fault (k=1) The average value is taken as the fault distance

[0119] The smoothed value set of state variables at the time of fault The formula for calculating the average value is:

[0120]

[0121] Step S107: According to the fault distance Calculate the three-phase currents on both sides of the fault point and determine the fault type based on the relationship between the three-phase currents.

[0122] According to the fault distance The specific process of calculating the three-phase current on both sides of the fault point is:

[0123] Three-phase current phasors on the left and right sides of the fault point and The calculation formulas are

[0124]

[0125] In the formula,

[0126]

[0127]

[0128] The rules for identifying fault types based on three-phase current are:

[0129] Assume j (j=a,b,c) is the fault identifier of phase j, where s j =0 means there is no fault in this phase, s j =1 indicates that the phase is faulty;

[0130] like Then suppose s j =1, where ε is the preset threshold value;

[0131] If a +s b +s c =3, it can be judged as a three-phase fault;

[0132] If a +s b +s c =2 and If the fault is between two phases, it can be judged as a two-phase fault; otherwise, it is a two-phase grounding fault. The specific fault phase depends on s j Is it 1, if a corresponding s j If the value is 1, it indicates a fault;

[0133] If a +s b +s c =1, it can be judged as a single-phase grounding fault. The specific fault phase depends on s j Is it 1, if a corresponding s j If the value is 1, it indicates a fault.

[0134] It can be seen from the above scheme that the power transmission system fault identification method provided in the embodiment of the present application can make full use of the limited data in the window, improve the accuracy of the fault estimation distance through forward filtering and backward smoothing, and then identify the fault type, which can effectively overcome the problem of reduced estimation accuracy caused by limited line collection data after the fault.

[0135] This embodiment discloses a power transmission system fault identification device. For the specific working contents of each unit in the device, please refer to the contents of the above method embodiment.

[0136] The power transmission system fault identification device provided by an embodiment of the present invention is described below. The power transmission system fault identification device described below and the power transmission system fault identification method described above can be referenced to each other.

[0137] See also Figure 2 , the power transmission system fault identification device disclosed in the present application may include:

[0138] Data acquisition unit A, first calculation unit B, second calculation unit C, third calculation unit D, fourth calculation unit E and fault analysis unit F;

[0139] Corresponding to the above method, the data acquisition unit is used to obtain the three-phase voltage phasor and the three-phase current phasor at the left end bus of the line and the three-phase voltage phasor and the three-phase current phasor at the right end bus at time k when a fault occurs, through the relay protection device or the synchronous phasor unit, k = 1, 2, ..., k max , where k is the kth time point in the data sequence collected by the relay protection device or the synchronous phasor unit in the power transmission system, the time when the fault occurs is the time k=1, and the k max The time point is the maximum time of the data sequence collected by the relay protection device or the synchronized phasor unit, and the relay protection device or the synchronized phasor unit is a relay protection device or a synchronized phasor unit installed at the left and right busbars of the power transmission system line;

[0140] A first calculation unit is used to obtain an initial state variable set X0 of the fault distance of the transmission system line equivalent model;

[0141] The second calculation unit is used to forward calculate the gain matrix K of the power transmission system at time k starting from the fault time point based on the initial state variable set X0. k and the state variable correction value set X k ;

[0142] The third calculation unit is used to calculate the gain matrix K based on the k and the set of state variable correction values, from k max Start from the time point and calculate the smoothed value set of the state variables at time k backward

[0143] The fourth calculation unit is used to calculate the smoothed value set of the state variables at the time of the fault The average value of the fault distance

[0144] A fault analysis unit is used to analyze the fault distance according to the Calculate the three-phase currents on both sides of the fault point and determine the fault type based on the relationship between the three-phase currents.

[0145] Corresponding to the above method, the present application also discloses a power transmission system fault identification device, see Figure 3 As shown, it may include: at least one processor 100, at least one communication interface 200, at least one memory 300 and at least one communication bus 400;

[0146] In the embodiment of the present invention, the number of the processor 100, the communication interface 200, the memory 300, and the communication bus 400 is at least one, and the processor 100, the communication interface 200, and the memory 300 communicate with each other through the communication bus 400; obviously, Figure 3 The communication connections shown for the processor 100, the communication interface 200, the memory 300, and the communication bus 400 are merely optional;

[0147] Optionally, the communication interface 200 may be an interface of a communication module, such as an interface of a GSM module;

[0148] The processor 100 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention.

[0149] The memory 300 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0150] The processor 100 is specifically configured to:

[0151] When a fault occurs, the relay protection device or the synchronous phasor unit is used to obtain the three-phase voltage phasor and the three-phase current phasor at the left end bus of the line and the three-phase voltage phasor and the three-phase current phasor at the right end bus at time k, k = 1, 2, ..., k max , where k is the kth time point in the data sequence collected by the relay protection device or the synchronous phasor unit in the power transmission system, the time when the fault occurs is the time k=1, and the k max The time point is the maximum time of the data sequence collected by the relay protection device or the synchronized phasor unit, and the relay protection device or the synchronized phasor unit is a relay protection device or a synchronized phasor unit installed at the left and right busbars of the power transmission system line;

[0152] Obtaining an initial state variable set X0 of the fault distance of the transmission system line equivalent model;

[0153] Based on the initial state variable set X0, forward calculation of the transmission system gain matrix K at time k starts from the fault time point kand the state variable correction value set X k ;

[0154] Based on the gain matrix K k and the set of state variable correction values, from k max Start from the time point and calculate the smoothed value set of the state variables at time k backward

[0155] Calculate the smoothed value set of the state variables at the time of failure The average value of the fault distance

[0156] According to the fault distance Calculate the three-phase currents on both sides of the fault point and determine the fault type based on the relationship between the three-phase currents.

[0157] For the convenience of description, the above system is described as being divided into various modules according to their functions. Of course, when implementing the present invention, the functions of each module can be implemented in the same or multiple software and / or hardware.

[0158] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0159] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0160] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0161] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0162] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for identifying faults in a power transmission system, characterized in that: include: When a fault occurs, the relay protection device or the synchronous phasor unit is used to obtain the three-phase voltage phasor and the three-phase current phasor at the left end bus of the line and the three-phase voltage phasor and the three-phase current phasor at the right end bus at time k, k = 1, 2, ..., k max , where k is the kth time point in the data sequence collected by the relay protection device or the synchronous phasor unit in the power transmission system, the time when the fault occurs is the time k=1, and the k max The time point is the maximum time of the data sequence collected by the relay protection device or the synchronized phasor unit, and the relay protection device or the synchronized phasor unit is a relay protection device or a synchronized phasor unit installed at the left and right busbars of the power transmission system line; Obtaining an initial state variable set X0 of the fault distance of the transmission system line equivalent model; Based on the initial state variable set X0, forward calculation of the transmission system gain matrix K at time k starts from the fault time point k and the state variable correction value set X k ; Based on the gain matrix K k and the set of state variable correction values, from k max Start from the time point and calculate the smoothed value set of the state variables at time k backward Calculate the smoothed value set of the state variables at the time of failure The average value of the fault distance According to the fault distance Calculate the three-phase currents on both sides of the fault point and determine the fault type based on the relationship between the three-phase currents.

2. The power transmission system fault identification method according to claim 1, characterized in that: The initial state variable set X0 of the fault distance of the transmission system line equivalent model is obtained, including: Based on the formula Calculate the initial value of the fault distance Among them, the D t is the total length of the transmission system lines; Obtain the variance P0 of the state variable determined based on prior knowledge; from Sampling M variables x from the distribution 0.i =D 0.i (i=1,2,...,M) constitutes the initial state variable set X0={x 0.i }(i=1,2,...,M), where M is a positive integer greater than 1, D 0.i is the fault distance in the i-th variable among the sampled M variables.

3. The power transmission system fault identification method according to claim 2, characterized in that: The gain matrix K of the power transmission system is calculated forward from the fault time point at time k. k ,include: Based on the formula Starting from the fault time point, forward calculation of the transmission system gain matrix K at time k k ; Output variable estimated value set for k time, For collection The i-th variable of ; for The average value set, 1 1×M is a 1×M-dimensional all-1 matrix; R is the covariance matrix of measurement noise; In the formula, v i ~N(0,R) is the i-th measurement noise; are the voltage phasors on the left and right of the fault point calculated using the estimated fault distance at time k; in, is the estimated value set of state variables at time k The i-th element of They are the three-phase voltage phasors and three-phase current phasors at the left busbar of the line at time k respectively; are the three-phase voltage phasors and three-phase current phasors at the busbar on the right side of the line at time k; ω is the electrical angular frequency; the matrices R(l), L(l), and C(l) are the resistance matrix, inductance matrix, and capacitance matrix functions of the line length, respectively. l is any line length. For the line on the left side of the fault point, For the line on the right side of the fault point 4. The power transmission system fault identification method according to claim 3, characterized in that: Starting from the fault time point, calculate the set of state variable correction values ​​X of the transmission system at time k k ,include: Based on the formula Starting from the fault time point, calculate the set of state variable correction values ​​X of the transmission system at time k k ; Where, X k ={x k.i }(i=1,2,...,M) is the set of state variable correction values ​​at time k, x k.i =D k.i is the correction value of the i-th state variable at time k; is the estimated value set of state variables at time k; is the set of estimated deviation values ​​of the state variables at time k; in, Where, X k-1 ={x (k-1).i }(i=1,2,...,M) is the set of state variable correction values ​​at time k-1, and when k=1, X k-1 =X0,x (k-1).i =D (k-1).i is the modified value of the i-th state variable at time k-1; W k-1 ={w (k-1).i }(i=1,2,...,M) is the process noise set at time k, w (k-1).i It obeys N(0,Q) distribution, where Q is its variance.

5. The power transmission system fault identification method according to claim 4, characterized in that: From k max Start from the time point and calculate the smoothed value set of the state variables at time k backward include: Based on the formula From k max Start from the time point and calculate the smoothed value set of the state variables at time k backward In the formula, is the set of smoothed values ​​of the state variables at time k, k+1=k max hour is the set of smoothed deviation values ​​of the state variables at time k+1, 6. The method for identifying power transmission system faults according to claim 5, characterized in that: The calculating of the state variable smoothing value set The average values ​​include: Based on the formula Calculate the state variable smoothing value set The average value of .

7. The method for identifying power transmission system faults according to claim 6, characterized in that: The fault distance Calculate the three-phase currents on both sides of the fault point, including: Based on the formula calculate The three-phase current phasors i on the left and right sides of the fault point l and i r ; The rules for identifying fault types based on three-phase current are: Determine the fault type based on the three-phase current relationship, including: Assume j (j=a,b,c) is the fault identifier of phase j, where s j =0 means there is no fault in this phase, s j =1 indicates that the phase is faulty; like Then suppose s j =1, where ε is the threshold value; If a +s b +s c =3, it can be judged as a three-phase fault; If a +s b +s c =2 and It can be judged as a two-phase phase-to-phase fault; otherwise, it is a two-phase grounding fault; If a +s b +s c =1, it can be judged as a single-phase grounding fault.

8. A power transmission system fault identification device, characterized in that: include: The data acquisition unit is used to obtain the three-phase voltage phasor and the three-phase current phasor at the left end bus of the line and the three-phase voltage phasor and the three-phase current phasor at the right end bus at time k when a fault occurs, through the relay protection device or the synchronous phasor unit, k=1,2,…,k max , where k is the kth time point in the data sequence collected by the relay protection device or the synchronous phasor unit in the power transmission system, the time when the fault occurs is the time k=1, and the k max The time point is the maximum time of the data sequence collected by the relay protection device or the synchronized phasor unit, and the relay protection device or the synchronized phasor unit is a relay protection device or a synchronized phasor unit installed at the left and right busbars of the power transmission system line; A first calculation unit is used to obtain an initial state variable set X0 of the fault distance of the transmission system line equivalent model; The second calculation unit is used to forward calculate the gain matrix K of the power transmission system at time k starting from the fault time point based on the initial state variable set X0. k and the state variable correction value set X k ; The third calculation unit is used to calculate the gain matrix K based on the k and the set of state variable correction values, from k max Start from the time point and calculate the smoothed value set of the state variables at time k backward The fourth calculation unit is used to calculate the smoothed value set of the state variables at the time of the fault The average value of the fault distance A fault analysis unit is used to analyze the fault distance according to the Calculate the three-phase currents on both sides of the fault point and determine the fault type based on the relationship between the three-phase currents.

9. A power transmission system fault identification device, characterized in that: include: Memory, used to store programs; The processor is used to execute the program to implement the various steps of the power transmission system fault identification method as described in any one of claims 1 to 6.

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