System and method for determining the distance to a fault in a power system network

Abstract

This application provides a method for determining the distance to a fault in a power system network. The method may involve determining a set of processed voltage samples based on a set of measured voltage samples; determining a set of processed reactive current samples, a set of processed resistive current samples, a set of processed negative sequence current samples, and a set of processed zero sequence current samples based on a set of measured current samples; selecting selected processed voltage samples, selected processed reactive current samples, selected processed resistive current samples, and selected processed negative or zero sequence current samples based on an indication from a fault phase indicator; determining, based on the selected processed reactive current samples, that no distortion has occurred due to current transformer (CT) saturation; and calculating the distance to a fault based on the determination that no distortion has occurred.

Description

[Technical Field]

[0001] This application and the resulting patents relate in general to power system networks, and more specifically to systems and methods for determining the distance to fault in power system networks. [Background technology]

[0002] Generally speaking, fault locations in cable and / or overhead line systems using phasor-based single-ended fault locator algorithms are inaccurate during current transformer (CT) saturation. Therefore, there is a growing need for methods to accurately calculate the distance to fault in specific types of systems based on single-ended measurement samples unaffected by CT saturation.

[0003] This not only reduces the requirements of existing CTs, but also reduces the fault location error rate using single-ended measurements to less than 2% for both single-line-to-ground (SLG) faults and phase-to-phase (-to-ground) faults with a resistance of 20 ohms and a source impedance ratio (SIR) of 10. In addition, the fault location can remain accurate even during severe CT saturation, reaching 1 / 4 cycle of the saturation onset time and 1 / 2 cycle of the maximum saturation duration in each fundamental frequency cycle. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent Application Publication No. 2017 / 315168 [Overview of the project]

[0005] Accordingly, this application and the resulting patent provide a method for determining the distance to a fault in a power system network. The method includes the steps of: determining a set of processed voltage samples based at least in part on a set of measured voltage samples; determining a set of processed reactive current samples and a set of processed resistive current samples based at least in part on a set of measured current samples; determining a set of processed negative sequence current samples and a set of processed zero sequence current samples based at least in part on a set of measured current samples; and selecting a set of processed voltage samples from the set of processed voltage samples, a set of processed reactive current samples, and a set of processed resistive current samples, based at least in part on an indication from a fault phase indicator. The process may include the steps of selecting a set of processed negative or zero-sequence current samples from a set of processed resistive current samples and a set of processed negative sequence current samples or a set of processed zero-sequence current samples; determining, at least partially, that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to current transformer (CT) saturation; and calculating the distance to failure based at least partially on the determination that no distortion has occurred, the selected processed voltage samples, the selected processed reactive current samples, the selected processed resistive current samples, and the selected processed negative or zero-sequence current samples.

[0006] This application and the resulting patent further provide a method for determining the distance to a fault in a power system network. The method includes the steps of: receiving a set of measured voltage samples and a set of measured current samples; determining a set of processed voltage samples, at least partially based on the set of measured voltage samples; determining a set of processed reactive current samples and a set of processed resistive current samples, at least partially based on the set of measured current samples; determining a set of processed negative sequence current samples and a set of processed zero sequence current samples, at least partially based on the set of measured current samples; receiving an indication from a fault phase indicator; and determining a selected processed voltage sample from the set of processed voltage samples and a selected processed reactive current sample from the set of processed reactive current samples, at least partially based on the indication. The process may include the steps of selecting a sample, a selected processed resistive current sample from a set of processed resistive current samples, and a selected processed negative or zero-sequence current sample from a set of processed negative-sequence current samples or a set of processed zero-sequence current samples; determining, at least partially, that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to current transformer (CT) saturation; and calculating the distance to failure based at least partially on the determination that no distortion has occurred, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero-sequence current sample.

[0007] This application and the resulting patent further provide a power system network. The power system network is a power line, and the set of measured voltage samples and the set of measured current samples may include a power line associated with a section of the power line and faults located on the power line, the set of processed voltage samples is determined at least in part on the set of measured voltage samples, the set of processed reactive current samples, the set of processed resistive current samples, the set of processed negative sequence current samples, and the set of processed zero sequence current samples is determined at least in part on the set of measured current samples, the selected processed voltage samples from the set of processed voltage samples, the selected processed reactive current samples from the set of processed reactive current samples, and the selected processed resistive current samples from the set of processed resistive current samples The selected processed negative or zero-sequence current samples from the set of processed resistive current samples and the set of processed negative sequence current samples or the set of processed zero-sequence current samples are selected at least in part based on indications from the fault phase indicator, the determination that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to current transformer (CT) saturation is made at least in part based on the selected processed reactive current samples, and the distance to fault is calculated at least in part based on the determination that no distortion has occurred, the selected processed voltage samples, the selected processed reactive current samples, the selected processed resistive current samples, and the selected processed negative or zero-sequence current samples.

[0008] These and other features and improvements of this application and the resulting patent will become apparent to those skilled in the art by examining the following detailed description in conjunction with some drawings and the attached claims. [Brief explanation of the drawing]

[0009] [Figure 1]This is a schematic diagram of an algorithm for calculating the distance to failure according to one or more exemplary embodiments of the present disclosure. [Figure 2] This is a schematic diagram of a power system network according to one or more exemplary embodiments of the present disclosure. [Figure 3] Figure 1 is a schematic diagram of the algorithm for preparing voltage and current samples. [Figure 4] Figure 1 is a schematic diagram of the algorithm for selecting fault phase voltage and current samples. [Figure 5] Figure 1 is a schematic diagram of the algorithm for detecting CT saturation. [Figure 6] Figure 1 is a flowchart illustrating the calculation of the distance to failure using the algorithm shown. [Modes for carrying out the invention]

[0010] Referring to the diagrams here, similar symbols throughout several diagrams refer to similar elements, and Figure 1 is a schematic diagram 100 of an algorithm for calculating the distance to fault. Schematic diagram 100 may be applicable to fault distance calculation in power system networks. In block 102, voltage and current samples can be prepared and processed to remove the attenuating DC component in order to formulate the equation for calculating the distance to fault. This process can be further illustrated in Figure 3. In block 104, relevant faulty phase processed voltage and current samples can be selected and the equation for calculating the distance to fault can be formulated. The selection of relevant faulty phase processed voltage and current samples from various processed voltage and current samples can be performed using the FtPhsInd input. This process can be further illustrated in Figure 4. In block 104, the algorithm is U P (n), I 0_Neg (n), I PR (n), and IPX The parameters associated with (n) can be output.

[0011] In block 106, I PX (n) output can be processed for a determination as to whether the voltage or current samples are distorted due to current transformer (CT) saturation. If the samples are not distorted due to CT saturation, block 106 can output a CT saturation indication digital signal CTSatInd = 1. If the samples are distorted due to CT saturation, block 106 can output a CT saturation indication digital signal CTSatInd = 0. This process can be further illustrated in FIG. 5. In block 108, when a digital signal indicating no CT saturation is received from block 106, the distance to the fault can be calculated by formulating an equation using the output of block 104 related to the processed voltage and current samples for the associated fault phase. This process can be further illustrated in FIG. 6.

[0012] FIG. 2 is a schematic diagram 200 of a power system network. As illustrated in FIG. 2, the power system network can have a plurality of power sources. Thus, a fault F can be located between points M and N in the power system network. The distance between points M and N can be denoted as L. In FIG. 2, the distance to the fault F indicated by x is the distance between M where the fault locator is deployed and F where the fault has occurred. At point M, the applicable voltage and current can be measured by the fault locator as U M and I M as indicated. Assuming that the fault F has a fault resistance of R g , the fault F can be further characterized by the voltage U F and the current I F .

[0013] Thus, the time domain phase equation for x can be as follows:

Equation

[0014] In the case of a single-phase-to-ground fault, the following time-domain phase equation may apply:

number

[0015] In the case of a phase-phase fault, the following time-domain phase equations may apply:

number

[0016] In the above equation, p = A, B, or C, pp = AB, BC, or CA,

number

number

[0017] When the time-domain phase equation with respect to x is sampled, the following equation may apply:

number

[0018] That is, U p (n) = K g I0(n)+[R1I MR (n) + X1I MX (n)]x, U pp (n) = K g I2(n)+[R1I MR (n) + X1I MX (n)]x. These equations can then be applied when calculating the distance to failure. For example, as shown in Figure 6, matrix Y M An equation can be applied when generating it.

[0019] Figure 3 is a schematic diagram 300 of the algorithm for preparing voltage and current samples using the algorithm illustrated in Figure 1. The algorithm for preparing voltage and current samples can be applied in block 102 of Figure 1. The algorithm can prepare voltage and current samples by implementing functions such as the averaging function 320, the resistance and reactive current determination function 322, the negative sequence converter function 324, and the differential function 326. At the local terminal, samples of each phase voltage and phase current can be measured. The samples are u A (n)302A, u B (n)302B, and u C (n) Three-phase voltage samples such as 302C, and i A (n)304A, i B (n)304B, and i C (n) Three-phase current samples such as 304C may be included. Three-phase voltage samples 302A~C and three-phase current samples 304~C may be inputs to the algorithm for preparing the voltage and current samples. Although not shown in Figure 3, another set of inputs to the algorithm for preparing the voltage and current samples may include a positive sequence impedance z1 per unit length and a zero sequence impedance z0 per unit length, where z1 = R1 + jX1 and z0 = R0 + jX0, as shown in Figure 1.

[0020] The averaging function 320 calculates the average of two samples. For example, if the averaging function 320 receives the input x(n), it can calculate the sum of x(n) and x(n-1) and multiply that sum by 0.5. Therefore, the output y(n) of the averaging function 320 can be calculated as follows:

number

[0021] Therefore, the processed three-phase voltage sample U A (n)306A, U B (n)306B, and U C (n)306C uses the averaging function 320 to sample three phase voltages u A (n)302A, u B (n)302B, and u C This can be determined by applying (n)302C. That is, the following equation can be applied:

number

number

number

number

number

[0022] The resistance and reactive current determination function 322 is i x When receiving inputs (n) and i0(n)308, the reactive portion of the current i xReact (n) = i x (n)+K X i0(n) It is possible to measure K X This is a coefficient for compensating for reactive current with zero-sequence current,

number

[0023] The differential function 326 calculates the derivative of two samples. For example, if the differential function 326 receives the input x(n), it calculates the difference between x(n) and x(n-1) and then calculates the derivative of that difference.

number

number

[0024] Therefore, when the differential function 326 is applied to the reactive portion of the current, the processed reactive current I xX (n). That is,

number

number

[0025] The negative sequence converter function 324 calculates negative current samples based on phase current samples (e.g., i A (n)304A, i B (n)304B, and i C (n)304C). Therefore, the output i X2 (n) of the negative sequence converter function 324 can be determined at least in part based on the application of the z -Nspc / 3 function to the input, which is the phase current sample. Thus, the negative sequence converter function 324 uses the following equation to output negative current samples i A2 (n)316A, i B2 (n)316B, and i C2 (n)316C.

Number

[0026] Next, the processed negative current sample I A2 (n)318A can be determined by applying the differentiation function 326 to the negative current sample i A2 (n)316A. That is,

Number

Number

number

[0027] Figure 4 is a schematic diagram 400 of the algorithm for selecting fault phase voltage and current samples. The type of fault can be indicated in order to select the fault phase voltage and current samples. The fault phase indicator 402 can display a number from 1 to 10 to indicate the type of fault present in the power system network. For example, the fault phase indicator can display 1 for phase-A-ground fault, 2 for phase-B-ground fault, 3 for phase-C-ground fault, 4 for phase-BC fault, 5 for phase-CA fault, 6 for phase-AB fault, 7 for phase-BC-ground fault, 8 for phase-CA-ground fault, 9 for phase-AB-ground fault, and 10 for phase-ABC fault or phase-ABC-ground fault.

[0028] If the fault phase indicator 402 shows 1, U P (n) = U A (n), I PR (n) = i AR (n), I PX (n) = I AX (n), and I 0_Neg (n) = I0(n). When the fault phase indicator 402 shows 2, U P (n) = U B (n), I PR (n) = I BR (n), I PX (n) = I BX (n), and I 0_Neg (n) = I0(n). When the fault phase indicator 402 shows 3, U P (n) = U C (n), I PR (n) = I CR (n), I PX (n) = I CX (n), and I 0_Neg(n) = I0(n). If the fault phase indicator 402 shows 4 or 7, U P (n) = U B (n)-U C (n), I PR (n) = I BR (n)-I CR (n), I PX (n) = I BX (n)-I CX (n), and I 0_Neg (n) = I A2 (n) If the fault phase indicator 402 shows 5 or 8, U P (n) = U C (n)-U A (n), I PR (n) = I CR (n)-I AR (n), I PX (n) = I CX (n)-I AX (n), and I 0_Neg (n) = I B2 (n) If the fault phase indicator 402 shows 6, 9, or 10, U P (n) = U A (n)-U B (n), I PR (n) = I AR (n)-I BR (n), I PX (n) = I AX (n)-I BX (n), and I 0_Neg (n) = I C2 (n)

[0029] Figure 5 illustrates a schematic diagram of the algorithm 500 for determining whether this sample is distorted due to CT saturation. The algorithm for detecting CT saturation takes a fault phase indicator as input, for example, the output of fault phase indicator 402 in Figure 4, I PX (n) can be received. PX (n) can represent the processed reactive current. Input I PX(n) may be input to a short-window algorithm for computing a full-cycle Fourier phasor 502. That is, the short-window algorithm for computing a full-cycle Fourier phasor 502 may be a 1 / 4-cycle Fourier phasor. Then, the short-window algorithm for computing a full-cycle Fourier phasor 502 takes input I PX By convolving (n) with the set of complex coefficients h(k), PhsI PX (n) can be output. Convolution can be performed by applying the following equation:

number

[0030] The matrix H is given by H=(A T A) -1 A H It can be calculated by,

number

number

number

number

number

number

[0031] PhsI PX After (n) is calculated, PhsI PX The size of (n) can be determined. PhsI PX The magnitude of (n) is PhsI PX The absolute value of (n) may be reflected. The absolute function 504 is PhsI PX (n) can be applied, PhsI PX (n) Absolute value I MP It is calculated as follows:

number

number

[0032] Next, the difference component 508 is I as the input. MP (n) and I MPavConst (n) is received, I MP(n) and I MPavConst The difference between (n) and (n) can be determined. That is, ΔI MP (n) = I MP (n)-I MPavConst (n) Next, the difference may be input to the absolute difference component 510 to determine its absolute value. That is,

number

[0033] Next, the absolute value |ΔI MP (n)| can be input to the threshold function 512. The threshold function 512 can further accept a predetermined error threshold as input. For example, the predetermined error threshold may be set to 1. Absolute value |ΔI MP If (n)| is less than a given error threshold, the sample is eligible and the algorithm can output CTSatInd=1. This indicates that the sample is not currently distorted by CT saturation. Absolute value |ΔI| MP If (n)| is greater than or equal to a predetermined error threshold, the sample is not eligible and the algorithm may output CTSatInd=0. This indicates that the sample is currently distorted by CT saturation.

[0034] In some cases, the algorithm is I PX (n) accepts multiple inputs, |ΔI MP CTSatInd can only be output if it is determined that the three values ​​of (n) are either less than or greater than a predetermined error threshold.

[0035] Figure 6 is a flowchart illustrating the calculation of the distance to failure. If the sample is shown to be eligible by the algorithm output CTSatInd=1, a matrix for calculating the distance to failure can be generated using the voltage and current parameters corresponding to the sample, as well as other parameters. For example, I PXIf (n) is a sample that yielded an algorithm output of CTSatInd=1, the corresponding parameter is U P (n), I PR (n), and I PX (n) can be included. To calculate the distance to failure, matrix Y M and A M First, we can formulate this. A matrix can be formulated as follows:

number

number

[0036] In particular, if the fault is detected as a single-phase-to-ground fault, the fault is I 0Neg (n) = I0(n), but for all other failures, I 0Neg (n) = I Neg (n) X1 and R1 are coefficients K R and K X The matrix Y was previously used to calculate the following: M and A M The generation of is illustrated in block 602.

[0037] Next, the distance to failure can be calculated by solving the following matrix equation: Y M =A M ·X

number

[0038] Once the distance to failure is determined, control actions can be performed based on that determination. For example, these control actions may involve generating a warning to the operator.

[0039] It is clear that the above pertains only to specific embodiments of this application and the resulting patent. Those skilled in the art can make numerous changes and modifications herein without departing from the general spirit and scope of the invention as defined by the following claims and equivalents.

[0040] Further aspects of the present invention are provided by the subject matter of the following clauses.

[0041] 1. A method for determining the distance to a fault in a power system network, comprising: determining a set of processed voltage samples based at least in part on a set of measured voltage samples; determining a set of processed reactive current samples and a set of processed resistive current samples based at least in part on a set of measured current samples; determining a set of processed negative sequence current samples and a set of processed zero sequence current samples based at least in part on the set of measured current samples; and determining a selected processed voltage sample from the set of processed voltage samples, a selected processed reactive current sample from the set of processed reactive current samples, and a processed resistive current sample based at least in part on an indication from a fault phase indicator. A method comprising: selecting a selected processed resistive current sample from a set of samples, and a selected processed negative or zero-sequence current sample from a set of processed negative-sequence current samples or a set of processed zero-sequence current samples; determining, at least partially, that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to current transformer (CT) saturation; and calculating the distance to the fault based at least partially on the determination that no distortion has occurred, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero-sequence current sample.

[0042] 2. The method of Clause 1, wherein calculating the distance to the failure based at least in part on the determination that no distortion has occurred is to formulate a set of equations for calculating the distance to the failure, the set of equations being based at least in part on the set of measured voltage samples and the set of measured current samples, and further comprising calculating the distance to the failure based at least in part on the set of equations, the determination that no distortion has occurred, the selected processed voltage samples, the selected processed reactive current samples, the selected processed resistive current samples, and the selected processed negative or zero sequence current samples.

[0043] 3. The method of any one of claims 1 to 2, wherein calculating the distance to the fault based at least in part on the determination that no distortion has occurred further comprises formulating a first matrix based at least in part on the selected processed voltage samples, formulating a second matrix based at least in part on the selected processed reactive current samples, the selected processed resistive current samples, and the selected processed negative or zero sequence current samples, and calculating the distance to the fault based at least in part on the first matrix and the second matrix.

[0044] 4. The method according to any one of the claims 1 to 3, wherein determining that no distortion has occurred due to current transformer (CT) saturation on at least a portion of the selected processed reactive current sample further comprises: calculating the full-cycle Fourier phasor current in a portion of the full cycle on at least a portion of the selected processed reactive current sample; calculating the magnitude of the full-cycle Fourier phasor current; calculating the average magnitude of the full-cycle Fourier phasor current over 1 / 8 of the cycle; and determining the difference between the average magnitude of the full-cycle Fourier phasor current over 1 / 8 of the cycle and a constant, wherein the constant is determined on at least a portion of the magnitude of the full-cycle Fourier phasor current in the portion of the full cycle after the occurrence of the fault.

[0045] 5. The method according to any one of the claims 1 to 4, wherein determining that no distortion has occurred due to CT saturation on a basis at least partially in the selected processed reactive current sample further includes determining that the difference is less than a predetermined error threshold, determining that no distortion has occurred due to CT saturation in response to the determination that the difference is less than the predetermined error threshold, and outputting an output of "1" based on the determination that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to CT saturation.

[0046] 6. Determining the processed set of voltage samples based at least in part on the measured set of voltage samples further comprises receiving the measured set of voltage samples, applying an averaging function to the measured set of voltage samples, and determining the processed set of voltage samples, wherein the processed set of voltage samples includes the output of the averaging function, according to any one of claims 1 to 5.

[0047] 7. Determining the set of processed reactive current samples and the set of processed resistive current samples based at least in part on the set of measured current samples further comprises receiving the set of measured current samples, determining the set of processed resistive currents based at least in part on the set of measured current samples, applying an averaging function to the set of processed resistive currents, and determining the set of processed resistive current samples, wherein the set of processed resistive current samples includes the output of the averaging function, according to any one of the claims 1 to 6.

[0048] 8. The method according to any one of the claims 1 to 7, wherein determining the set of processed reactive current samples and the set of processed resistive current samples based at least in part on the set of measured current samples further comprises receiving the set of measured current samples, determining the set of processed reactive currents based at least in part on the set of measured current samples, applying a differential function to the set of processed reactive currents, and determining the set of processed reactive current samples, wherein the set of processed reactive current samples includes the output of the differential function.

[0049] 9. The method according to any one of the clauses 1 to 8, wherein the indication from the fault phase indicator indicates the type of fault associated with the fault.

[0050] 10. A method for determining the distance to a fault in a power system network, comprising: receiving a set of measured voltage samples and a set of measured current samples; determining a set of processed voltage samples based at least in part on the set of measured voltage samples; determining a set of processed reactive current samples and a set of processed resistive current samples based at least in part on the set of measured current samples; determining a set of processed negative sequence current samples and a set of processed zero sequence current samples based at least in part on the set of measured current samples; receiving an indication from a fault phase indicator; and determining a selected processed voltage sample from the set of processed voltage samples and a selected sample from the set of processed reactive current samples based at least in part on the indication. A method comprising: selecting a processed reactive current sample, a selected processed resistive current sample from the set of processed resistive current samples, and a selected processed negative or zero sequence current sample from the set of processed negative sequence current samples or the set of processed zero sequence current samples; determining, at least partially, on the selected processed reactive current sample, that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to current transformer (CT) saturation; and calculating the distance to the fault based at least partially on the determination that no distortion has occurred, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample.

[0051] 11. The method of Clause 10, wherein calculating the distance to the failure based at least in part on the determination that no distortion has occurred is to formulate a set of equations for calculating the distance to the failure, the set of equations being based at least in part on the set of measured voltage samples and the set of measured current samples, and further comprising calculating the distance to the failure based at least in part on the set of equations, the determination that no distortion has occurred, the selected processed voltage samples, the selected processed reactive current samples, the selected processed resistive current samples, and the selected processed negative or zero sequence current samples.

[0052] 12. The method of any one of the claims 10 to 11, wherein calculating the distance to the failure based at least in part on the determination that no distortion has occurred further comprises formulating a first matrix based at least in part on the selected processed voltage samples, formulating a second matrix based at least in part on the selected processed reactive current samples, the selected processed resistive current samples, and the selected processed negative or zero sequence current samples, and calculating the distance to the failure based at least in part on the first matrix and the second matrix.

[0053] 13. The method according to any one of the claims 10 to 12, wherein determining that no distortion has occurred due to current transformer (CT) saturation on at least a portion of the selected processed reactive current sample further comprises: calculating the full-cycle Fourier phasor current in a portion of the full cycle on at least a portion of the selected processed reactive current sample; calculating the magnitude of the full-cycle Fourier phasor current; calculating the average magnitude of the full-cycle Fourier phasor current over 1 / 8 of the cycle; and determining the difference between the average magnitude of the full-cycle Fourier phasor current over 1 / 8 of the cycle and a constant, wherein the constant is determined on at least a portion of the magnitude of the full-cycle Fourier phasor current in the portion of the full cycle after the occurrence of the fault.

[0054] 14. The method according to any one of the claims 10 to 13, wherein determining that no distortion has occurred due to CT saturation on a basis at least in part in the selected processed reactive current sample further includes determining that the difference is less than a predetermined error threshold, determining in response to the determination that the difference is less than the predetermined error threshold that no distortion has occurred due to CT saturation, and outputting an output of "1" based on the determination that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to CT saturation.

[0055] 15. The method according to any one of the claims 10 to 14, wherein determining the set of processed voltage samples based at least in part on the set of measured voltage samples further comprises receiving the set of measured voltage samples, applying an averaging function to the set of measured voltage samples, and determining the set of processed voltage samples, wherein the set of processed voltage samples includes the output of the averaging function.

[0056] 16. Determining the set of processed reactive current samples and the set of processed resistive current samples based at least in part on the set of measured current samples further comprises receiving the set of measured current samples, determining the set of processed resistive currents based at least in part on the set of measured current samples, applying an averaging function to the set of processed resistive currents, and determining the set of processed resistive current samples, wherein the set of processed resistive current samples includes the output of the averaging function, according to any one of the claims 10 to 15.

[0057] 17. The method according to any one of the claims 10 to 16, wherein determining the set of processed reactive current samples and the set of processed resistive current samples based at least in part on the set of measured current samples further comprises receiving the set of measured current samples, determining the set of processed reactive currents based at least in part on the set of measured current samples, applying a differential function to the set of processed reactive currents, and determining the set of processed reactive current samples, wherein the set of processed reactive current samples includes the output of the differential function.

[0058] 18. Power system network, power line, set of measured voltage samples and set of measured current samples, comprising power line associated with a section of the power line and faults located on the power line, wherein the set of processed voltage samples is determined at least in part on the set of measured voltage samples, and the set of processed reactive current samples, set of processed resistive current samples, set of processed negative sequence current samples, and set of processed zero sequence current samples are determined at least in part on the set of measured current samples, and selected processed voltage samples from the set of processed voltage samples, selected processed reactive current samples from the set of processed reactive current samples, selected processed resistive current samples from the set of processed resistive current samples A power system network in which a selected processed negative or zero-sequence current sample is selected from a set of resistive-current samples and the set of processed negative-sequence current samples or the set of processed zero-sequence current samples, at least in part on indications from a fault phase indicator, and a determination that no distortion has occurred in the set of measured voltage samples and the set of measured current samples due to current transformer (CT) saturation is made at least in part on the selected processed reactive current sample, and the distance to the fault is calculated at least in part on the determination that no distortion has occurred, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive-current sample, and the selected processed negative or zero-sequence current sample.

[0059] 19. The distance to the fault is calculated based at least in part on a set of equations that are at least in part on the set of measured voltage samples and the set of measured current samples, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample, as described in Clause 18.

[0060] 20. The determination that, based at least partially on the selected processed reactive current sample, no distortion has occurred due to current transformer (CT) saturation, is made by, based at least partially on the selected processed reactive current sample, calculating the full-cycle Fourier phasor current in a portion of the full cycle, calculating the magnitude of the full-cycle Fourier phasor current, calculating the average magnitude of the full-cycle Fourier phasor current over 1 / 8 of the cycle, and determining the difference between the average magnitude of the full-cycle Fourier phasor current over 1 / 8 of the cycle and a constant. A power system network according to any one of clauses 18 to 19, further comprising determining the constant at least in part on the magnitude of the full-cycle Fourier phasor current in the portion of the full cycle after the occurrence of the fault, determining that the difference is less than a predetermined error threshold, determining in response to the determination that the difference is less than the predetermined error threshold that no distortion has occurred due to the CT saturation, and outputting an output of "1" based on the determination that no distortion has occurred in the measured set of voltage samples and the measured set of current samples due to the CT saturation. [Explanation of Symbols]

[0061] 100 Schematic Diagram 102 blocks 104 blocks 106 blocks 108 blocks 200 Schematic Diagram 300 Schematic Diagram 302A Three-phase voltage sample / set of measured voltage samples 302B Three-phase voltage samples / Set of measured voltage samples 302C Three-phase voltage samples / Set of measured voltage samples 304A Three-Phase Current Samples / Set of Measured Current Samples 304B Three-phase current sample / set of measured current samples 304C Three-Phase Current Samples / Set of Measured Current Samples 306A Processed three-phase voltage sample / Set of processed voltage samples 306B Processed three-phase voltage samples / Set of processed voltage samples 306C Processed three-phase voltage samples / Set of processed voltage samples 308 Total Current Samples 310 Processed current samples 312A Processed Resistance Current / Set of Processed Resistance Current Samples 312B Processed Resistance Current / Set of Processed Resistance Current Samples Set of 312C processed resistance current / processed resistance current samples 314A Processed Reactive Current / Set of Processed Reactive Current Samples 314B Processed Reactive Current / Set of Processed Reactive Current Samples 314C Processed Reactive Current / Set of Processed Reactive Current Samples 316A Negative Current Sample 316B Negative Current Sample 316C Negative Current Sample 318A Set of processed negative current samples / processed negative sequence current samples 318B Set of processed negative current samples / processed negative sequence current samples 318C Set of processed negative current samples / processed negative sequence current samples 320 Averaging Function 322 Resistance and Reactive Current Determination Function 324 Negative Sequence Converter Function 326 Differential Functions 400 Schematic Diagram 402 Fault Phase Indicator 500 Schematic Diagram 502 Full-cycle Fourier phasor 504 Absolute Function 506 Averaged component 508 Differential Components 510 Absolute difference component 512 Threshold function 600 flowcharts 602 blocks 604 blocks

Claims

1. A method for determining the distance to a fault in a power system network, Based at least partially on the measured set of voltage samples (302A-C), the set of processed voltage samples (306A-C) is determined, Based at least partially on the measured set of current samples (304A-C), the set of processed reactive current samples (314A-C) and the set of processed resistive current samples (312A-C) are determined, Based at least partially on the measured set of current samples (304A to C), determine the set of processed negative sequence current samples (318A to C) and the set of processed zero sequence current samples, Selecting a selected processed voltage sample from the set of processed voltage samples (306A-C), a selected processed reactive current sample from the set of processed reactive current samples (314A-C), a selected processed resistive current sample from the set of processed resistive current samples (312A-C), and a selected processed negative or zero-sequence current sample from the set of processed negative current samples (318A-C) or the set of processed zero-sequence current samples, at least partially based on instructions from the fault phase indicator (402), Based at least partially on the selected processed reactive current samples, it is determined that no distortion has occurred in the set of measured voltage samples (302A-C) and the set of measured current samples (304A-C) due to current transformer (CT) saturation. Calculating the distance to the fault based at least in part on the determination that no distortion has occurred, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample. Methods that include...

2. Calculating the distance to the failure based at least in part on the aforementioned determination that no distortion has occurred is, Formulating a set of equations for calculating the distance to the fault, wherein the set of equations is at least partially based on the set of measured voltage samples (302A to C) and the set of measured current samples (304A to C), Calculating the distance to the fault based at least in part on the set of equations, the determination that no distortion has occurred, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample. The method according to claim 1, further comprising:

3. Calculating the distance to the failure based at least in part on the aforementioned determination that no distortion has occurred is, Formulating a first matrix based at least partially on the selected processed voltage samples, Formulating a second matrix based at least partially on the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample, Calculating the distance to the failure based at least partially on the first matrix and the second matrix. The method according to claim 2, further comprising:

4. Determining, at least partially, that no distortion has occurred in the selected processed reactive current sample due to current transformer (CT) saturation means that Based at least partially on the selected processed reactive current samples, the full-cycle Fourier phasor (502) current in a portion of the full cycle is calculated, To calculate the magnitude of the full-cycle Fourier phasor (502) current, Calculate the average magnitude of the full-cycle Fourier phasor (502) current during 1 / 8 of the cycle, Determining the difference between the average magnitude of the full-cycle Fourier phasor (502) current during 1 / 8 of the cycle and a constant, wherein the constant is determined at least in part on the magnitude of the full-cycle Fourier phasor (502) current in the portion of the full cycle after the occurrence of the fault. The method according to claim 1, further comprising:

5. Determining that no distortion has occurred in the selected processed reactive current sample due to CT saturation, at least on a partial basis, is: It is determined that the difference is less than a predetermined error threshold, In response to the determination that the difference is less than the predetermined error threshold, it is determined that no distortion has occurred due to the CT saturation. Based on the determination that no distortion has occurred in the measured voltage sample set (302A-C) and the measured current sample set (304A-C) due to CT saturation, an output of "1" is output. The method according to claim 4, further comprising:

6. Determining the set of processed voltage samples (306A-C) based at least partially on the set of measured voltage samples (302A-C) is: To receive the set of measured voltage samples (302A to C), Applying the averaging function (320) to the set of measured voltage samples (302A to C), The process involves determining the set of processed voltage samples (306A to C), wherein the set of processed voltage samples (306A to C) includes the output of the averaging function (320). The method according to claim 1, further comprising:

7. Determining the set of processed reactive current samples (314A-C) and the set of processed resistive current samples (312A-C) based at least partially on the set of measured current samples (304A-C) is: To receive the set of measured current samples (304A to C), Determine a set of resistance currents (312A to C) that has been processed at least partially based on the set of measured current samples (304A to C), Applying the averaging function (320) to the processed set of resistance currents (312A to C), The set of processed resistance current samples (312A to C) is determined such that the set of processed resistance current samples (312A to C) includes the output of the averaging function (320). The method according to claim 1, further comprising:

8. Determining the set of processed reactive current samples (314A-C) and the set of processed resistive current samples (312A-C) based at least partially on the set of measured current samples (304A-C) is: To receive the set of measured current samples (304A to C), To determine a set of reactive currents (314A to C) that has been processed at least partially based on the set of measured current samples (304A to C), Applying the differential function (326) to the processed set of reactive currents (314A to C), The process involves determining the set of processed reactive current samples (314A to C), wherein the set of processed reactive current samples (314A to C) includes the output of the differential function (326). The method according to claim 7, further comprising:

9. The method according to claim 1, wherein the indication from the fault phase indicator (402) indicates the type of fault associated with the fault.

10. A power system network, A power line, wherein a set of measured voltage samples (302A-C) and a set of measured current samples (304A-C) are associated with a section of the power line, A fault located on the aforementioned power line and Equipped with, The set of processed voltage samples (306A-C) is determined at least in part based on the set of measured voltage samples (302A-C), The set of processed reactive current samples (314A-C), the set of processed resistive current samples (312A-C), the set of processed negative sequence current samples (318A-C), and the set of processed zero sequence current samples are determined at least in part based on the set of measured current samples (304A-C). A selected processed voltage sample from the set of processed voltage samples (302A-C), a selected processed reactive current sample from the set of processed reactive current samples (314A-C), a selected processed resistive current sample from the set of processed resistive current samples (312A-C), and a selected processed negative or zero-sequence current sample from the set of processed negative current samples (318A-C) or the set of processed zero-sequence current samples are selected at least in part based on an indication from the fault phase indicator (402). The determination that no distortion has occurred in the measured set of voltage samples (302A-C) and the measured set of current samples (304A-C) due to current transformer (CT) saturation is made at least in part on the selected processed reactive current samples. The distance to the fault is calculated at least in part on the determination that no distortion has occurred, the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample. Power system network.

11. The power system network according to claim 10, wherein the distance to the fault is calculated based at least in part on a set of equations based at least in part on the set of measured voltage samples (302A to C) and the set of measured current samples (304A to C), the selected processed voltage sample, the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample.

12. The distance to the fault, calculated at least in part based on the determination that no distortion has occurred, Formulating a first matrix based at least partially on the selected processed voltage samples, Formulating a second matrix based at least partially on the selected processed reactive current sample, the selected processed resistive current sample, and the selected processed negative or zero sequence current sample, Calculating the distance to the failure based at least partially on the first matrix and the second matrix. The power system network according to claim 11, further comprising:

13. The determination that the selected processed reactive current sample is not distorted due to current transformer (CT) saturation, based at least partially, Based at least partially on the selected processed reactive current samples, the full-cycle Fourier phasor (502) current in a portion of the full cycle is calculated, To calculate the magnitude of the full-cycle Fourier phasor (502) current, Calculate the average magnitude of the full-cycle Fourier phasor (502) current during 1 / 8 of the cycle, Determining the difference between the average magnitude of the full-cycle Fourier phasor (502) current during 1 / 8 of the cycle and a constant, wherein the constant is determined at least in part on the magnitude of the full-cycle Fourier phasor (502) current in the portion of the full cycle after the occurrence of the fault. The power system network according to claim 10, further comprising:

14. The determination that the selected processed reactive current sample is not distorted due to current transformer (CT) saturation, based at least partially, It is determined that the difference is less than a predetermined error threshold, In response to the determination that the difference is less than the predetermined error threshold, it is determined that no distortion has occurred due to the CT saturation. Based on the determination that no distortion has occurred in the measured voltage sample set (302A-C) and the measured current sample set (304A-C) due to CT saturation, an output of "1" is output. The power system network according to claim 13, further comprising:

15. The power system network according to claim 10, wherein the indication from the fault phase indicator (402) indicates the type of fault associated with the fault.

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