Single-phase earth fault diagnosis method and system based on fault current resistive component

Abstract

The single-phase ground fault diagnosis method and system based on fault current resistance component include processing measurement data to obtain three-phase steady-state resistance components of all lines and Pearson correlation coefficients between ground charge and voltage of each line; the ratio of the maximum value of three-phase steady-state resistance components to the average value of steady-state resistance wind subset after removing the maximum value of three-phase steady-state resistance components is calculated, and the single-phase ground fault set of fault current steady-state resistance component is obtained based on the ratio; the single-phase ground fault set of ground charge-voltage ratio curve is obtained based on the Pearson correlation coefficient between ground charge and voltage; and the intersection of the single-phase ground fault set of fault current steady-state resistance component and the single-phase ground fault set of ground charge-voltage ratio curve is taken as the line where the single-phase ground fault occurs. The application adopts two types of criteria, steady state and transient state, to determine two single-phase ground fault sets, and finally uses the group comparison method to select lines and phases, so that the fault diagnosis is accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of intelligent power distribution network operation analysis, in particular to a single-phase ground fault diagnosis method and system based on fault current resistive component. BACKGROUND

[0002] The traditional fault line selection method is to realize line selection by manually opening the switch. When a fault occurs in the system, the staff manually opens the switch of each feeder one by one. If the fault signal disappears after a certain line is disconnected, the line is the fault line. This method not only wastes a lot of manpower, but also greatly increases the power outage time and probability, making it difficult to guarantee the power supply reliability. For a long time, some research results have been achieved in single-phase ground fault line selection and positioning: such as the method of using steady-state quantity, the method based on fault transient signal, the traveling wave method, the S injection method and the method of multiplying the zero sequence current by the impedance of the neutral point. However, there are still problems such as invalidation of line selection criterion under high resistance fault or difficulty in extracting signal, and the signal characteristics are not obvious. The problem of single-phase ground fault line selection and section positioning in the neutral point non-effective grounding distribution network has not been well solved. SUMMARY

[0003] In order to solve the problems of the prior art methods of using steady-state quantity, the method based on fault transient signal, the traveling wave method, the S injection method and the method of multiplying the zero sequence current by the impedance of the neutral point, such as invalidation of line selection criterion under high resistance fault or difficulty in extracting signal, and the signal characteristics are not obvious, the present application provides a single-phase ground fault diagnosis method based on fault current resistive component, which comprises:

[0004] Processing the measurement data to obtain the steady-state resistive component of three-phase-to-ground current of all lines and the Pearson correlation coefficient between the ground charge and voltage of each line;

[0005] Calculating the ratio of the maximum value of the steady-state resistive component of three-phase-to-ground current to the average value of the steady-state resistive component of the subset of all lines except the maximum value of the steady-state resistive component of three-phase-to-ground current, and obtaining a single-phase ground fault set of the fault current steady-state resistive component based on the ratio;

[0006] Obtaining a single-phase ground fault set of the ground charge-voltage ratio curve based on the Pearson correlation coefficient between the ground charge and voltage;

[0007] Taking the intersection of the single-phase ground fault set of the fault current steady-state resistive component and the single-phase ground fault set of the ground charge-voltage ratio curve as the line where the single-phase ground fault occurs.

[0008] Optionally, the processing of the measurement data to obtain the steady-state resistive component of three-phase-to-ground current of all lines and the Pearson correlation coefficient between the ground charge and voltage of each line comprises:

[0009] The measurement data is calculated by using regression analysis method to obtain steady-state resistance components of three-phase-to-ground currents of all lines;

[0010] The measurement data is calculated by using orthogonal decomposition method to obtain fault current static rectangular coordinate system components;

[0011] Based on the fault current static rectangular coordinate system components and the line voltage transient quantity and the line-to-ground parameter in the measurement data, a line-to-ground charge-voltage numerical pair is obtained;

[0012] The linear degree of the line-to-ground charge-voltage data pair of each line is analyzed by using Pearson correlation coefficient method to obtain the Pearson correlation coefficient between the line-to-ground charge and the voltage.

[0013] Optionally, the measurement data is calculated by using orthogonal decomposition method to obtain fault current static rectangular coordinate system components, comprising:

[0014] The line-to-ground charge-voltage numerical pair is obtained based on the line-to-ground charge-voltage data pair of each line.

[0015] The line-to-ground charge-voltage numerical pair is obtained based on the line-to-ground charge-voltage data pair of each line.

[0016] The line-to-ground charge-voltage numerical pair is obtained based on the line-to-ground charge-voltage data pair of each line.

[0017] The line-to-ground charge-voltage numerical pair is obtained based on the line-to-ground charge-voltage data pair of each line.

[0018] The line-to-ground charge-voltage numerical pair is obtained based on the line-to-ground charge-voltage data pair of each line.

[0019] Optionally, the measurement data is calculated by using orthogonal decomposition method to obtain fault current static rectangular coordinate system components, comprising:

[0020] The line-to-ground charge-voltage numerical pair is obtained based on the line-to-ground charge-voltage data pair of each line.

[0021] Based on the instantaneous value of the ground current of each phase line and the transient instantaneous value of the line head voltage in the measurement data, the instantaneous value of the ground current of each phase line in normal line transient and fault line transient is calculated respectively;

[0022] Based on the instantaneous value of the ground current of each phase line, the line-to-ground capacitance, the line-to-ground conductance and the transient instantaneous value of the line head voltage of each phase, the ground charge of the normal line is calculated;

[0023] Based on the instantaneous value of the ground current of each phase line, the line-to-ground capacitance, the line-to-ground conductance and the transient instantaneous value of the line head voltage of each phase, the ground charge of the normal line is calculated;

[0024] Based on the ground charge of the normal line and the ground charge of the fault line, the ground charge-voltage numerical pair is formed with the line voltage transient;

[0025] The ground parameters include the instantaneous value of the ground current, the line-to-ground capacitance and the line-to-ground conductance.

[0026] Optionally, the linear degree of the ground charge and the voltage data pair of each line is analyzed by using the Pearson correlation coefficient method, and the Pearson correlation coefficient between the ground charge and the voltage is obtained, including:

[0027] Based on the ground charge and the voltage data pair of each line, the average value of the ground charge and the average value of the voltage are calculated;

[0028] Based on the average value of the ground charge, the average value of the voltage, the ground charge and the line voltage transient of each line, the Pearson correlation coefficient between the ground charge and the voltage is calculated by using the Pearson correlation coefficient method.

[0029] Optionally, the Pearson correlation coefficient between the ground charge and the voltage is calculated according to the following formula:

[0030]

[0031] In the formula, r is the Pearson correlation coefficient between the ground charge and the voltage, q(t j ) is the cumulative charge from t0 to t j , q is the average value of the ground charge, u1 is the average value of the voltage, u1(t j ) is the line voltage transient at the jth moment, m is the total number of moments, and j is the moment.

[0032] Optionally, the regression analysis method is used to calculate the measurement data, and the steady-state resistive component of the three-phase ground current of all lines is obtained, including:

[0033] The rectangular coordinate components of the line current at the beginning of the line are calculated based on the measured data, the phase voltage at the beginning of the line, and the phase difference between the line current and the phase voltage at the beginning of the line.

[0034] The rectangular coordinate components of the line current at the end of the line are calculated based on the line end current, the phase voltage at the end of the line, and the phase difference of the line current in the measurement data.

[0035] The rectangular coordinate components of the line current at the beginning and end of the line are analyzed using linear regression to obtain the steady-state resistive components of the three-phase ground current of all lines.

[0036] Optionally, the set of single-phase ground faults for obtaining the steady-state resistive component of the fault current based on the ratio includes:

[0037] Determine whether the ratio satisfies the single-phase grounding fault criterion;

[0038] If the single-phase grounding fault criterion is met, then the phase line corresponding to the ratio has a single-phase grounding fault; otherwise, no single-phase grounding fault has occurred.

[0039] Optionally, the single-phase ground fault criterion is as follows:

[0040]

[0041] In the formula, p represents the maximum value of the steady-state resistive component and The ratio of the average, p set The threshold for the relative value criterion of steady-state resistive components. for The maximum value of the steady-state resistive component, I set The threshold value is used as the criterion for the absolute value of the steady-state resistive component.

[0042] Optionally, the set of single-phase ground faults for which the ground charge-voltage ratio curve is obtained based on the Pearson correlation coefficient between the ground charge and voltage includes:

[0043] Determine whether the Pearson correlation coefficient between the charge to ground and the voltage of each phase of the line is greater than the first linear relationship threshold or less than the second linear threshold. If the line phase is greater than the first linear relationship threshold or less than the second linear threshold, it is determined that a single-phase grounding fault has occurred in the charge to ground-voltage ratio curve.

[0044] Wherein, the first linear relationship threshold is (1-β), the second linear relationship threshold is (1+β), and β is the consistency judgment threshold.

[0045] Furthermore, this invention also provides a single-phase ground fault diagnosis system based on the resistive component of fault current, comprising:

[0046] a data processing module configured to process the measurement data to obtain three-phase-to-ground current steady-state resistance components of all lines and Pearson correlation coefficients between ground charge and voltage of each line;

[0047] a first fault judging module configured to calculate a ratio of a maximum value of the three-phase-to-ground current steady-state resistance components to an average value of a subset of steady-state resistance windings after removing the maximum value of the three-phase-to-ground current steady-state resistance components, and obtain a single-phase-to-ground fault set of the fault current steady-state resistance components based on the ratio;

[0048] a second fault judging module configured to obtain a single-phase-to-ground fault set of a ground charge-voltage ratio curve based on the Pearson correlation coefficients between the ground charge and the voltage;

[0049] a fault diagnosing module configured to take an intersection of the single-phase-to-ground fault set of the fault current steady-state resistance components and the single-phase-to-ground fault set of the ground charge-voltage ratio curve as a line where a single-phase-to-ground fault occurs.

[0050] Compared with the prior art, the method has the following beneficial effects:

[0051] The method for diagnosing single-phase-to-ground faults based on fault current resistance components provided by the application comprises the following steps: processing measurement data to obtain three-phase-to-ground current steady-state resistance components of all lines and Pearson correlation coefficients between ground charge and voltage of each line; calculating a ratio of a maximum value of the three-phase-to-ground current steady-state resistance components to an average value of a subset of steady-state resistance windings after removing the maximum value of the three-phase-to-ground current steady-state resistance components, and obtaining a single-phase-to-ground fault set of the fault current steady-state resistance components based on the ratio; obtaining a single-phase-to-ground fault set of a ground charge-voltage ratio curve based on the Pearson correlation coefficients between the ground charge and the voltage; and taking an intersection of the single-phase-to-ground fault set of the fault current steady-state resistance components and the single-phase-to-ground fault set of the ground charge-voltage ratio curve as a line where a single-phase-to-ground fault occurs. The method adopts both steady-state and transient-state criteria to judge the value and characteristics of the fault current resistance components, and finally realizes line selection and phase selection by using a group ratio comparison method, so that the fault diagnosis is accurate and the problems such as failure of line selection criterion or difficulty in extracting signals and unobvious signal characteristics under high-resistance faults are overcome. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 FIG. 1 is a flow chart of a method for diagnosing single-phase-to-ground faults based on fault current resistance components according to the application;

[0053] Figure 2 FIG. 3 is a three-phase equivalent circuit diagram of single-phase-to-ground faults according to the application;

[0054] Figure 3A schematic diagram of the orthogonal decomposition principle of the present application. DETAILED DESCRIPTION

[0055] After a single-phase grounding fault, the fault phase of the fault line has a fault current containing the entire system's resistive current due to the presence of the fault grounding branch, which is significantly different from the non-fault line. Although the resistive current component has a small absolute value, by comparing the fault phase with the normal phase and the fault line with the normal line, the diagnosis result of the line state can be obtained. Therefore, the present application proposes a method for extracting whether there is a significant increase in resistive current in the steady state and transient state, and fuses the steady state and transient state methods to realize single-phase grounding fault diagnosis of the line.

[0056] Embodiment 1

[0057] A single-phase grounding fault diagnosis method based on fault current resistive component, as shown in Figure 1 , comprising:

[0058] S1: processing the measurement data to obtain the steady-state resistive component of the three-phase-to-ground current of all lines and the Pearson correlation coefficient between the charge-to-ground and voltage of each line;

[0059] S2: calculating the ratio of the maximum value of the steady-state resistive component of the three-phase-to-ground current to the average value of the steady-state resistive component subset after removing the maximum value of the steady-state resistive component of the three-phase-to-ground current, and obtaining a single-phase grounding fault set of the fault current steady-state resistive component based on the ratio;

[0060] S3: obtaining a single-phase grounding fault set of the charge-to-ground to voltage ratio curve based on the Pearson correlation coefficient between the charge-to-ground and voltage;

[0061] S4: taking the intersection of the single-phase grounding fault set of the fault current steady-state resistive component and the single-phase grounding fault set of the charge-to-ground to voltage ratio curve as the line where the single-phase grounding fault occurs.

[0062] The purpose of the present application is to provide a single-phase grounding fault diagnosis method based on fault current resistive component, comprising the following steps:

[0063] Specifically includes S1:

[0064] S1.1 uses a regression analysis method to calculate the measurement data to obtain the steady-state resistive component of the three-phase-to-ground current of all lines;

[0065] S1.2 uses an orthogonal decomposition method to calculate the measurement data to obtain the fault current stationary rectangular coordinate component;

[0066] S1.3 Analyzing the ground charge quantity-voltage numerical pairs based on the fault current static rectangular coordinate system components and the line voltage transient quantity and line-to-ground parameter in the measurement data;

[0067] S1.4 Analyzing the linearity degree of the ground charge quantity and voltage data pairs of each line by using the Pearson correlation coefficient method to obtain the Pearson correlation coefficient between the ground charge quantity and the voltage.

[0068] Before S1, it includes reading the measurement data, and the specific process is as follows:

[0069] As shown in the single-phase ground fault phase equivalent circuit diagram shown in Figure 2 , the line current, phase voltage, active power and reactive power at the beginning and end of the line are read.

[0070] (1) Reading the line current at the beginning of the line:

[0071]

[0072] In the formula, I1 is the line current data set at the beginning of the line, I1 i is the i-th data value of the line current at the beginning of the line.

[0073] (2) Reading the line current at the end of the line:

[0074]

[0075] In the formula, I2 is the line current data set at the end of the line, is the i-th data value of the line current at the end of the line.

[0076] (3) Reading the phase voltage at the beginning of the line:

[0077]

[0078] In the formula, U1 is the phase voltage data set at the beginning of the line, is the i-th data value of the phase voltage at the beginning of the line.

[0079] (4) Reading the phase voltage at the end of the line:

[0080]

[0081] In the formula, U2 is the phase voltage data set at the end of the line, is the i-th data value of the phase voltage at the end of the line.

[0082] (5) Reading the active power at the beginning of the line:

[0083] P1={P1 1 ,P1 2 ,...,P1 i..., P1 n} (5)

[0084] where P1 is a set of line head end active power data, P1 i is the i-th data value of line head end active power.

[0085] (6) Read line end active power:

[0086]

[0087] where P2 is a set of line end active power data, is the i-th data value of line end active power.

[0088] (7) Read line head end reactive power:

[0089]

[0090] where Q1 is a set of line head end reactive power data, is the i-th data value of line head end reactive power.

[0091] (8) Read line end reactive power:

[0092]

[0093] where Q2 is a set of line end reactive power data, is the i-th data value of line end reactive power.

[0094] (9) Read line impedance data.

[0095] Read line resistance as R and reactance as X.

[0096] S1.1 specifically comprises:

[0097] Step 1: Calculate the steady-state resistive component of fault current.

[0098] Step 1-1: Calculate the phase based on the orthogonal decomposition method.

[0099] (1) Calculate the line head end phase voltage and line current phase difference

[0100]

[0101] where, is the i-th data value of line head end reactive power, is the line head end phase voltage and line current phase difference, P1 i is the i-th data value of line head end active power.

[0102] (2) Calculate the phase difference between the line end phase voltage and the line current

[0103]

[0104] wherein, is the phase difference between the line end phase voltage and the line current, is the i-th data value of the line end reactive power, is the i-th data value of the line end active power.

[0105] (3) Calculate the phase difference δ between the line head and end phase voltages.

[0106]

[0107] wherein, δ is the phase difference between the line head and end phase voltages, is the i-th data value of the line end reactive power, is the i-th data value of the line end active power, R is the resistance of the line, and X is the reactance.

[0108] Step 1-2: Calculate the fault current static rectangular coordinate system components, as shown in Figure 3 .

[0109] (1) Calculate the rectangular coordinate system components of the line current at the line head.

[0110]

[0111] wherein, is the i-th set of head current data in the α-axis component in the rectangular coordinate system, is the i-th data value of the line head line current, is the phase difference between the line head phase voltage and the line current.

[0112] (2) Calculate the rectangular coordinate system components of the line current at the line end.

[0113]

[0114] wherein, is the i-th set of end current data in the α-axis component in the rectangular coordinate system, is the i-th data value of the line end line current, is the phase difference between the line end phase voltage and the line current, δ i is the phase difference between the line head and end.

[0115] Step 1-3: Calculate the steady-state resistive component of the fault current.

[0116] (1) The relationship between the resistive component of the fault current and the component of the phase current in the stationary rectangular coordinate system is established.

[0117]

[0118] where a is the linear regression coefficient, I is the resistive component of the fault current, I is the first end current data of the i-th group, α R is the component of the α-axis in the rectangular coordinate system, is the end current data of the i-th group, is the component of the α-axis in the rectangular coordinate system.

[0119] (2) The coefficient in equation (14) is calculated by using the linear regression method.

[0120]

[0121] where a is the linear regression coefficient, I is the resistive component of the fault current, I is the first end current data of the i-th group, α R is the component of the α-axis in the rectangular coordinate system, is the end current data of the i-th group, is the component of the α-axis in the rectangular coordinate system, n is the total number of data, and i is the data number.

[0122] (3) The steady-state resistive component of the fault current is calculated.

[0123]

[0124] where I is the steady-state resistive component of the fault current, a is the linear regression coefficient, R α is the first end current data of the i-th group, is the component of the α-axis in the rectangular coordinate system, is the end current data of the i-th group, is the component of the α-axis in the rectangular coordinate system, n is the total number of data, and i is the data number.

[0125] Step 2: Calculate the transient ground charge-voltage ratio curve of the fault current.

[0126] Step 2-1: Calculate the transient ground current.

[0127] Calculate the transient ground current.

[0128] Vi A (t) = i 1A (t) - i 2A ​​​​​​​​(t) (17)

[0129] Vi B (t) = i 1B (t) - i 2B (t) (18)

[0130] Vi C (t) = i 1C (t) - i 2C (t) (19)

[0131] where i 1A (t) is the instantaneous value of the line current at the beginning of the A-phase line at time t, i 2A (t) is the instantaneous value of the line current at the end of the A-phase line at time t, Vi A (t) is the instantaneous value of the ground current of the A-phase line at time t, Vi B (t) is the instantaneous value of the ground current of the B-phase line at time t, i 1B (t) is the instantaneous value of the line current at the beginning of the B-phase line at time t, i 2B (t) is the instantaneous value of the line current at the end of the B-phase line at time t, Vi C (t) is the instantaneous value of the ground current of the C-phase line at time t, i 1C (t) is the instantaneous value of the line current at the beginning of the C-phase line at time t, i 2C (t) is the instantaneous value of the line current at the end of the C-phase line at time t.

[0132] Step 2-2: Obtain the transient instantaneous value of the line beginning voltage u 1A (t), u 1B (t), and u 1C (t).

[0133] Step 2-3: Analyze the transient ground charge quantity-voltage ratio characteristic.

[0134] (1) If it is a normal line, the transient ground current is:

[0135]

[0136]

[0137]

[0138] where Vi A (t) is the instantaneous value of the ground current of the A-phase line at time t, Vi B (t) is the instantaneous value of the ground current of the B-phase line at time t, Vi C (t) is the instantaneous value of the ground current of the C-phase line at time t, C k is the line ground capacitance, G kG 1A (t), u 1B (t) and u 1C (t) are the transient instantaneous values of the line terminal A-phase, B-phase and C-phase voltages, respectively.

[0139] (2) If it is a fault line, the transient ground current is:

[0140]

[0141]

[0142]

[0143]

[0144] wherein Vi A (t) is the instantaneous value of the A-phase line-to-ground current at time t, C B (t) is the instantaneous value of the B-phase line-to-ground current at time t, C C (t) is the instantaneous value of the C-phase line-to-ground current at time t, C k is the line-to-ground capacitance, G k is the line-to-ground conductance, u 1A (t), u 1B (t) and u 1C (t) are the transient instantaneous values of the line terminal A-phase, B-phase and C-phase voltages, respectively, C f (t) is the ground fault current, C f is the equivalent ground capacitance of the grounding branch, G f is the equivalent ground conductance of the grounding branch.

[0145] (3) Calculate the line-to-ground charge quantity.

[0146] The voltage zero-crossing point is selected as the starting time t0.

[0147] For a normal line:

[0148]

[0149] wherein Vi A (t) is the instantaneous value of the A-phase line-to-ground current at time t, C k is the line-to-ground capacitance, G k is the line-to-ground conductance, u 1A (t) is the transient instantaneous value of the line terminal A-phase voltage at time t, u 1A (τ) is the transient instantaneous value of the line terminal A-phase voltage at time τ.

[0150] For a fault line:

[0151]

[0152] wherein Vi A (t) is the instantaneous value of the line-to-ground current of phase A at time t, C k is the line-to-ground capacitance, G k is the line-to-ground conductance, C f is the equivalent line-to-ground capacitance of the grounding branch, u 1A (t) is the transient instantaneous value of the line voltage of phase A at the line head, G f is the equivalent line-to-ground conductance of the grounding branch, u 1A (τ) is the transient instantaneous value of the line voltage of phase A at time τ at the line head.

[0153] (4) Analyzing the relationship between the line-to-ground charge and the voltage.

[0154] Since the line-to-ground conductance is much smaller than the capacitance in a normal line, the line-to-ground charge and the voltage present a linear relationship. In a fault line, due to the influence of the grounding branch, the conductance increases and cannot be ignored, so the line-to-ground charge and the voltage lose the linear relationship.

[0155] Step 2-2: Calculating the line-to-ground charge and voltage data pairs.

[0156] The line voltage transient is measured:

[0157] u1={u1(t1),u1(t2),...,u1(t j ),...,u1(t m )} (29)

[0158] wherein u1 is the set of line voltage transients, u1(t1), u1(t2), u1(t j ), and u1(t m ) are the line voltage transients at the 1st, 2nd, jth, and mth times, respectively, t j is the jth time, and m is the total number of times.

[0159] The line-to-ground charge is calculated:

[0160] q={q(t1),q(t2),...,q(t j ),...,q(t m )} (30)

[0161]

[0162] wherein q(t1) is the cumulative charge from t0 to t1, q(t j ) is the cumulative charge from t0 to t jThe cumulative charge, q(t2) is the cumulative charge from t0 to t2, q(t m ) is from t0 to t m The accumulated charge, t0 is the moment when the voltage crosses zero, t j Let Vi(τ) be the instantaneous value of the line-to-ground current of phase A at time j.

[0163] Then we can obtain the data pairs of charge to ground and voltage:

[0164] (q,u1)={(q(t1),u1(t1)),...,(q(t j ),u1(t j )),...,(q(t m ),u1(t m ))} (32)

[0165] In the formula, q(t1) is the cumulative charge from t0 to t1, q(t j ) is from t0 to t j The cumulative charge, q(t) m ) is from t0 to t m The cumulative charge, u1(t1), u1(t) j ) and u1(t m ) represent the transient line voltage values ​​at time points 1, j, and m, respectively, and t represents the transient line voltage values ​​at time points m, j, and m. j Let t be the j-th time, m be the total number of time points, and t be the time interval. m Let m be the m-th time.

[0166] Steps 2-3: Analyze the linearity of the data pairs of charge to ground and voltage using the Pearson correlation coefficient method.

[0167] Calculate the Pearson correlation coefficient between the charge to ground and the voltage:

[0168]

[0169] In the formula, r is the Pearson correlation coefficient between the charge to ground and the voltage, and q(t) j ) is from t0 to t j The cumulative charge, q is the average charge relative to ground, u1 is the average voltage, u1(t) j Let be the transient voltage of the line at time j.

[0170] A detailed introduction to S2:

[0171] Step 2-1: Fault diagnosis method based on steady-state resistive component of fault current.

[0172] (1) Calculate the steady-state resistive components of the three-phase ground current for all lines. and Forming a set of steady-state resistive components:

[0173]

[0174] where, is a set of three-phase steady-state resistive components of all lines, k represents the kth line, and w is the number of lines, is the steady-state resistive component of the A-phase to ground current of the 1st line, is the steady-state resistive component of the B-phase to ground current of the 1st line, is the steady-state resistive component of the C-phase to ground current of the 1st line, is the steady-state resistive component of the A-phase to ground current of the kth line, is the steady-state resistive component of the B-phase to ground current of the kth line, is the steady-state resistive component of the C-phase to ground current of the kth line, is the steady-state resistive component of the A-phase to ground current of the wth line, is the steady-state resistive component of the B-phase to ground current of the wth line, is the steady-state resistive component of the C-phase to ground current of the wth line.

[0175] (2) Calculating the maximum value in the set of steady-state resistive components:

[0176]

[0177] where, is the maximum value in is a set of three-phase steady-state resistive components of all lines.

[0178] (3) Calculating a subset of steady-state resistive components after removing the maximum value in the set:

[0179]

[0180] where, is the subset of steady-state resistive components after removing the maximum value in is the maximum value in is a set of three-phase steady-state resistive components of all lines.

[0181] (4) Calculating the average value of

[0182]

[0183] is the average value of all elements in the subset is the subset of steady-state resistive components after removing the maximum value in ​​​​​The steady-state resistive component of the fault current of phase X of line k is given by w, where w is the number of lines.

[0184] (5) Calculate the maximum value of the steady-state resistive component and The ratio of the average:

[0185]

[0186] In the formula, p represents the maximum value of the steady-state resistive component and The ratio of the mean, where E is a subset. The average of all elements in the set. for The maximum value of the steady-state resistive component.

[0187] (6) Criteria for determining a single-phase ground fault in phase X of line k:

[0188]

[0189] In the formula, p represents the maximum value of the steady-state resistive component and The ratio of the average, p set The threshold for the relative value criterion of steady-state resistive components. for The maximum value of the steady-state resistive component, I set The threshold value is used as the criterion for the absolute value of the steady-state resistive component.

[0190] (7) If a single-phase ground fault occurs, then... Repeat steps (1) to (6) to determine if there is still a single-phase grounding fault in the line; if there is no single-phase grounding fault, the single-phase grounding fault judgment process ends.

[0191] (8) Form a set of single-phase ground faults based on the steady-state resistive component of the fault current:

[0192] Z steady ={(k,X)} (40)

[0193] In the formula, Z steady Let k represent the set of single-phase grounding faults based on the steady-state resistive component of the fault current, where k represents the kth line and X represents a phase among A, B, and C.

[0194] S3 specifically includes the following steps:

[0195] Fault diagnosis method based on the fault current transient charge-to-ground ratio curve.

[0196] (1) Obtain the set of correlation coefficients as follows:

[0197]

[0198] wherein r is a set of Pearson correlation coefficients between the ground charge quantity and the voltage, respectively, the Pearson correlation coefficients between the ground charge quantity and the voltage of the A, B, C phases of the first line, wherein r is a set of Pearson correlation coefficients between the ground charge quantity and the voltage, respectively, the Pearson correlation coefficients between the ground charge quantity and the voltage of the A, B, C phases of the first line, wherein r is a set of Pearson correlation coefficients between the ground charge quantity and the voltage, respectively, the Pearson correlation coefficients between the ground charge quantity and the voltage of the A, B, C phases of the first line,

[0199] (2) If the correlation coefficient of the X phase of the kth line satisfies formula (42) or (43), the X phase of the kth line has a single-phase ground fault, otherwise, no single-phase ground fault occurs.

[0200]

[0201]

[0202] wherein, is the Pearson correlation coefficient between the ground charge quantity and the voltage of the X phase of the kth line, 1+β and 1-β are linear relationship thresholds, and β is a consistency judgment threshold.

[0203] (3) Form a single-phase ground fault set based on the ground charge-voltage ratio curve of the transient fault current:

[0204] Z transient = {(k,X)} (44)

[0205] wherein Z transient is a single-phase ground fault set based on the ground charge-voltage ratio curve of the transient fault current, k is a line number, and X is a reactance.

[0206] For S4, specifically comprising:

[0207] Comprehensive single-phase ground fault set Z steady based on the steady-state resistive component of the fault current transient and single-phase ground fault set Z steady based on the ground charge-voltage ratio curve of the transient fault current transient As a result, take the intersection Z as the final confirmed line of single-phase ground fault.

[0208] Z = Z steady ∪ Z transient (45)

[0209] wherein Z is the intersection of Z steady and Z transient , Z steady is a single-phase ground fault set of the steady-state resistive component of the fault current, and Z transient is a single-phase ground fault set based on the ground charge-voltage ratio curve of the transient fault current.

[0210] The application proposes a single-phase ground fault diagnosis method based on fault current resistance component, which is a single-phase ground fault current steady-state resistance component calculation method based on orthogonal decomposition. The steady-state resistance component in the fault current is obtained by using orthogonal decomposition and linear regression method. Then, an analytical method of the transient ground charge-voltage curve feature of the fault current is proposed. The linear degree of the ground charge and voltage is calculated based on Pearson correlation coefficient. Finally, a fault diagnosis fusion method based on group comparison is proposed to comprehensively utilize the fault diagnosis method based on the steady-state resistance component of the fault current and the ground charge-voltage ratio curve to diagnose the line state.

[0211] The application utilizes the resistance component of the fault branch current to implement the diagnosis method of single-phase ground fault. The diagnosis flow of single-phase ground fault is as follows: firstly, based on the calculation of fault current steady-state resistance component and the analysis of transient ground charge-voltage curve feature of the fault current, the steady-state and transient two types of criteria are respectively used to judge the resistance component value and feature of the fault current. Finally, the group comparison method is used to realize line selection and phase selection.

[0212] In the fault diagnosis fusion method based on group comparison, the steady-state criterion of the fault current resistance component is proposed. The steady-state resistance component significantly higher than the average degree and the corresponding line are obtained by using the correlation calculation of the fault current steady-state resistance component set.

[0213] In the fault diagnosis fusion method based on group comparison, the transient criterion of the fault current resistance component is proposed. The fault diagnosis method based on the transient ground charge-voltage ratio curve of the fault current is proposed. The ground charge-voltage ratio curve showing typical nonlinear characteristics and the corresponding line are obtained by analyzing the numerical value of the Pearson correlation coefficient. Finally, when a line is diagnosed as a single-phase ground fault by both the steady-state resistance component method and the ground charge-voltage method, it is determined that the line has a single-phase ground fault.

[0214] The application proposes a single-phase ground fault current steady-state resistance component calculation method based on orthogonal decomposition. The fault current stationary rectangular coordinate system is constructed. The phase relationship among the line current, voltage and fault current is analyzed. The relationship between the resistance component in the fault current and the stationary rectangular coordinate system component of the phase current is established by using multiple sets of measurement data. The method for calculating the steady-state resistance component in the fault current by using linear regression method is proposed.

[0215] The application provides an analytical method for a fault current transient ground charge quantity-voltage curve feature, and in a normal line, a ground conductance is much smaller than a capacitance, so that the ground charge quantity and the voltage present a linear relationship. In a fault line, due to the influence of a grounding branch, the conductance increases and cannot be ignored, so that the ground charge quantity and the voltage lose the linear relationship, and a linear degree calculation method for the ground charge quantity and the voltage based on a Pearson correlation coefficient is provided.

[0216] Embodiment 2

[0217] The application based on the same inventive concept also provides a single-phase ground fault diagnosis system based on a fault current resistive component, which comprises:

[0218] a data processing module, which is used for processing measurement data to obtain three-phase ground current steady-state resistive components of all lines and Pearson correlation coefficients between ground charge quantities and voltages of each line;

[0219] a first fault judgment module, which is used for calculating a ratio of a maximum value of the three-phase ground current steady-state resistive components to an average value of a steady-state resistive component subset after removing the maximum value of the three-phase ground current steady-state resistive components, and obtaining a single-phase ground fault set of the fault current steady-state resistive component based on the ratio;

[0220] a second fault judgment module, which is used for obtaining a single-phase ground fault set of a ground charge quantity-voltage ratio curve based on the Pearson correlation coefficients between the ground charge quantities and the voltages;

[0221] a fault diagnosis module, which is used for taking an intersection of the single-phase ground fault set of the fault current steady-state resistive component and the single-phase ground fault set of the ground charge quantity-voltage ratio curve as a line in which a single-phase ground fault occurs.

[0222] Further, the data processing module comprises:

[0223] a regression analysis submodule, which is used for calculating the measurement data by using a regression analysis method to obtain three-phase ground current steady-state resistive components of all lines;

[0224] a decomposition submodule, which is used for calculating the measurement data by using an orthogonal decomposition method to obtain fault current static rectangular coordinate system components;

[0225] an analytical submodule, which is used for analyzing the ground charge quantity-voltage numerical pairs based on the fault current static rectangular coordinate system components and line voltage transient quantities and line ground quantities in the measurement data;

[0226] a coefficient calculation submodule, which is used for analyzing the linear degree of the ground charge quantity and the voltage data pairs of each line by using a Pearson correlation coefficient method to obtain the Pearson correlation coefficients between the ground charge quantities and the voltages.

[0227] Further, the decomposition submodule is specifically configured to:

[0228] Based on the line head and tail end reactive power, active power, phase voltage and line current of the line, a quadrature decomposition method is used to obtain the phase difference of the line head and tail end phase voltage and line current, and the phase difference of the line head and tail end phase voltage;

[0229] Based on the line head phase voltage and line current phase difference and the line head reactive power and active power, the line head line current component in the rectangular coordinate system is calculated;

[0230] Based on the line tail end phase voltage and line current phase difference and the line tail end reactive power and active power, the line tail end line current component in the rectangular coordinate system is calculated;

[0231] Based on the line tail end reactive power, active power, resistance and reactance of the line, the phase difference of the line head and tail end phase voltage is calculated;

[0232] The fault current stationary rectangular coordinate system component includes: the line head line current component in the rectangular coordinate system, the line tail end line current component in the rectangular coordinate system, and the phase difference of the line head and tail end phase voltage.

[0233] Further, the analysis submodule is specifically configured to:

[0234] Based on the instantaneous value of the line head line current of each phase in the measurement data, the instantaneous value of the line-to-ground current of each phase is calculated;

[0235] Based on the instantaneous value of the line-to-ground current of each phase and the transient instantaneous value of the line head voltage in the measurement data, the instantaneous value of the line-to-ground current of each phase in the normal line transient state and the fault line transient state is calculated respectively;

[0236] Based on the instantaneous value of the line-to-ground current of each phase, the line-to-ground capacitance, the line-to-ground conductance and the transient instantaneous value of each phase voltage at the line head, the normal line-to-ground charge quantity is calculated;

[0237] Based on the instantaneous value of the line-to-ground current of each phase, the line-to-ground capacitance, the line-to-ground conductance, the transient instantaneous value of each phase voltage at the line head, the equivalent line-to-ground conductance of the grounding branch and the equivalent line-to-ground capacitance of the grounding branch, the fault line-to-ground charge quantity is calculated;

[0238] Based on the normal line-to-ground charge quantity and the fault line-to-ground charge quantity and the line voltage transient quantity, the line-to-ground charge quantity-voltage numerical pair is formed;

[0239] The line-to-ground parameter includes: the instantaneous value of the line-to-ground current, the line-to-ground capacitance and the line-to-ground conductance.

[0240] Further, the coefficient calculation sub-module is specifically configured to:

[0241] calculate average values of the ground charge quantity and voltage of each line based on the ground charge quantity and voltage data of each line;

[0242] calculate a Pearson correlation coefficient between the ground charge quantity and voltage based on the average values of the ground charge quantity and voltage of each line, the ground charge quantity, the line voltage transient quantity, and a Pearson correlation coefficient method.

[0243] The Pearson correlation coefficient between the ground charge quantity and voltage is calculated according to the following formula:

[0244]

[0245] In the formula, r is the Pearson correlation coefficient between the ground charge quantity and voltage, q(t j ) is the cumulative charge quantity from t0 to t j , q is the average value of the ground charge quantity, u1 is the average value of the voltage, u1(t j ) is the line voltage transient quantity at the jth moment, m is the total number of moments, and j is the moment.

[0246] Further, the regression analysis sub-module is specifically configured to:

[0247] calculate the rectangular coordinate system components of the line head line current based on the line head current, the line head phase voltage, and the line current phase difference in the measurement data;

[0248] calculate the rectangular coordinate system components of the line end line current based on the line end current, the line end phase voltage, and the line current phase difference in the measurement data;

[0249] analyze the rectangular coordinate system components of the line head line current and the rectangular coordinate system components of the line end line current by using a linear regression method to obtain the steady-state resistive components of the three-phase-to-ground current of all lines.

[0250] Further, the first fault judgment module is specifically configured to:

[0251] calculate the ratio of the maximum value of the three-phase-to-ground current steady-state resistive component to the average value of the steady-state resistive component after removing the maximum value of the three-phase-to-ground current steady-state resistive component;

[0252] determine whether the ratio meets a single-phase-to-ground fault criterion;

[0253] If the single-phase-to-ground fault criterion is met, the phase line corresponding to the ratio has a single-phase-to-ground fault; otherwise, no single-phase-to-ground fault occurs.

[0254] The single-phase-to-ground fault criterion is shown in the following formula:

[0255]

[0256] In the formula, p represents the maximum value of the steady-state resistive component and The ratio of the average, p set The threshold for the relative value criterion of steady-state resistive components. for The maximum value of the steady-state resistive component, I set The threshold value is used as the criterion for the absolute value of the steady-state resistive component.

[0257] Furthermore, the second fault diagnosis module is specifically used for:

[0258] Determine whether the Pearson correlation coefficient between the charge to ground and the voltage of each phase of the line is greater than the first linear relationship threshold or less than the second linear threshold. If the line phase is greater than the first linear relationship threshold or less than the second linear threshold, it is determined that a single-phase grounding fault has occurred in the charge to ground-voltage ratio curve.

[0259] Wherein, the first linear relationship threshold is (1-β), the second linear relationship threshold is (1+β), and β is the consistency judgment threshold.

[0260] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0261] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0262] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the flow Figure 1 The flow or flows and / or blocks Figure 1 The flow or flows and / or blocks

[0263] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions that execute on the computer or other programmable apparatus provide steps for implementing the flow Figure 1 The flow or flows and / or blocks Figure 1 The flow or flows and / or blocks

[0264] The above merely provides an embodiment of the present application, but is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the scope of the present application.

Claims

1. A single-phase earth fault diagnostic method based on the resistive component of the fault current, characterized in that, The method comprises the following steps: processing the measurement data to obtain the steady-state resistive components of three-phase-to-ground currents of all lines and the Pearson correlation coefficients between the ground charge and voltage of each line; calculating the ratio of the maximum value of the steady-state resistive components of three-phase-to-ground currents to the average value of a subset of the steady-state resistive components after removing the maximum value of the steady-state resistive components of three-phase-to-ground currents, and obtaining a single-phase-to-ground fault set of the steady-state resistive components of fault currents based on the ratio; obtaining a single-phase-to-ground fault set of the ground charge-voltage ratio curve based on the Pearson correlation coefficients between the ground charge and voltage; taking the intersection of the single-phase-to-ground fault set of the steady-state resistive components of fault currents and the single-phase-to-ground fault set of the ground charge-voltage ratio curve as the line where the single-phase-to-ground fault occurs.

2. The method of claim 1, wherein, The method of processing the measurement data to obtain the steady-state resistive components of three-phase-to-ground currents of all lines and the Pearson correlation coefficients between the ground charge and voltage of each line comprises: calculating the steady-state resistive components of three-phase-to-ground currents of all lines by using a regression analysis method; calculating the fault current components in the stationary rectangular coordinate system by using an orthogonal decomposition method; obtaining the ground charge-voltage numerical pairs based on the fault current components in the stationary rectangular coordinate system and the line voltage transient quantities and line-to-ground quantities in the measurement data; analyzing the linearity of the ground charge and voltage data pairs of each line by using a Pearson correlation coefficient method to obtain the Pearson correlation coefficients between the ground charge and voltage.

3. The method of claim 2, wherein, The method of calculating the fault current components in the stationary rectangular coordinate system by using an orthogonal decomposition method comprises: obtaining the phase differences between the line currents and voltages at the head and tail ends of a line based on the reactive power, active power, phase voltage and line current of the line at the head and tail ends in the measurement data by using an orthogonal decomposition method; calculating the components of the line current in the rectangular coordinate system at the head end of the line based on the phase differences between the line current and voltage at the head end and the reactive power and active power at the head end of the line; calculating the components of the line current in the rectangular coordinate system at the tail end of the line based on the phase differences between the line current and voltage at the tail end and the reactive power and active power at the tail end of the line; calculating the phase difference between the voltages at the head and tail ends of the line based on the reactive power, active power, resistance and reactance of the line at the tail end of the line; wherein the fault current components in the stationary rectangular coordinate system comprise the components of the line current in the rectangular coordinate system at the head and tail ends of the line, the phase difference between the voltages at the head and tail ends of the line.

4. The method of claim 2, wherein, The method of obtaining the ground charge-voltage numerical pairs based on the fault current components in the stationary rectangular coordinate system and the line voltage transient quantities and line-to-ground quantities in the measurement data comprises: calculating the instantaneous values of the line-to-ground currents of each phase based on the instantaneous values of the line currents at the head end of each phase in the measurement data; calculating the instantaneous values of the line-to-ground currents of each phase in the normal line transient state and fault line transient state respectively based on the instantaneous values of the line-to-ground currents of each phase and the transient instantaneous values of the line voltage in the measurement data; The normal line-to-ground charge quantity is calculated based on the instantaneous value of the line-to-ground current, the line-to-ground capacitance, the line-to-ground conductance and the transient instantaneous value of the phase voltage at the head of the line; The fault line-to-ground charge quantity is calculated based on the instantaneous value of the line-to-ground current, the line-to-ground capacitance, the line-to-ground conductance, the transient instantaneous value of the phase voltage at the head of the line, the equivalent ground conductance of the grounding branch and the equivalent ground capacitance of the grounding branch; The ground charge quantity-voltage numerical pair is constituted by the normal line-to-ground charge quantity, the fault line-to-ground charge quantity and the line voltage transient quantity. The ground parameters include the instantaneous value of the line-to-ground current, the line-to-ground capacitance and the line-to-ground conductance.

5. The method of claim 2, wherein, The linear degree of the ground charge quantity and the voltage data pair of each line is analyzed by using the Pearson correlation coefficient method to obtain the Pearson correlation coefficient between the ground charge quantity and the voltage, including: The average value of the ground charge quantity and the average value of the voltage of each line are calculated based on the ground charge quantity and the voltage data pair of each line; The Pearson correlation coefficient between the ground charge quantity and the voltage is calculated by using the Pearson correlation coefficient method based on the average value of the ground charge quantity, the average value of the voltage, the ground charge quantity and the line voltage transient quantity.

6. The method of claim 5, wherein, The Pearson correlation coefficient between the ground charge quantity and the voltage is calculated according to the following formula: where r is a Pearson correlation coefficient between the earth charge amount and the voltage, q(t j ) is a cumulative earth charge amount from t j , is an average of the earth charge amount, is an average of the voltage, u1(t j ) is a line voltage transient amount at the jth time, m is the total number of times, and j is the time.

7. The method of claim 2, wherein, The measurement data is calculated by using the regression analysis method to obtain the steady-state resistive component of the three-phase line-to-ground current of all lines, including: The rectangular coordinate system component of the line current at the head of the line is calculated based on the line current at the head of the line, the phase voltage at the head of the line and the line current phase difference in the measurement data; The rectangular coordinate system component of the line current at the end of the line is calculated based on the line current at the end of the line, the phase voltage at the end of the line and the line current phase difference in the measurement data; The steady-state resistive component of the three-phase line-to-ground current of all lines is obtained by analyzing the rectangular coordinate system component of the line current at the head of the line and the rectangular coordinate system component of the line current at the end of the line by using the linear regression method.

8. The method of claim 1, wherein, The single-phase ground fault set of the fault current steady-state resistive component is obtained based on the ratio, including: It is judged whether the ratio meets the single-phase ground fault criterion; If the single-phase ground fault criterion is met, the phase line corresponding to the ratio has a single-phase ground fault; otherwise, no single-phase ground fault occurs.

9. The method of claim 8, wherein, The single-phase ground fault criterion is shown in the following formula: where p is the ratio of the maximum value of the steady-state resistive component to the average value of the steady-state resistive component, p where p is the ratio of the maximum value of the steady-state resistive component to the average value of the steady-state resistive component, p set is a steady-state resistive component relative value criterion threshold, is a steady-state resistive component absolute value criterion threshold. is a steady-state resistive component maximum value, I set is a steady-state resistive component absolute value criterion threshold.

10. The method of claim 1, wherein, The single-phase ground fault set of the ground charge quantity-voltage ratio curve is obtained based on the Pearson correlation coefficient between the ground charge quantity and the voltage, including: It is judged whether the Pearson correlation coefficient between the ground charge quantity and the voltage of each phase of the line is greater than a first linear relationship threshold or less than a second linear threshold, and the line phase greater than the first linear relationship threshold or less than the second linear threshold is determined as having a single-phase ground fault of the ground charge quantity-voltage ratio curve; The first linear relationship threshold is (1-β) and the second linear relationship threshold is (1+β), where β is a consistency judgment threshold.

11. A single phase to ground fault diagnostic system based on the resistive component of the fault current, characterized in that, The data processing module is configured to process the measurement data to obtain the steady-state resistive component of the three-phase line-to-ground current of all lines and the Pearson correlation coefficient between the ground charge quantity and the voltage of each line. ​ a first fault judging module configured to calculate a ratio of a maximum value of a steady-state resistive component of a three-phase-to-ground current to an average value of a subset of the steady-state resistive component after removing the maximum value of the steady-state resistive component of the three-phase-to-ground current, and obtain a single-phase-to-ground fault set of the steady-state resistive component of the fault current based on the ratio; a second fault judging module configured to obtain a single-phase-to-ground fault set of a ground charge-to-voltage ratio curve based on a Pearson correlation coefficient between the ground charge and the voltage; a fault diagnosing module configured to take an intersection of the single-phase-to-ground fault set of the steady-state resistive component of the fault current and the single-phase-to-ground fault set of the ground charge-to-voltage ratio curve as a line in which a single-phase-to-ground fault occurs.

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