CN104730417B - It is a kind of using negative-sequence current as the transmission line of electricity method of single end distance measurement of amount of polarization - Google Patents

Abstract

The invention discloses a single-end ranging method of a transmission line using negative sequence current as the polarization quantity. Filter to obtain the current fundamental wave component and voltage fundamental wave component that eliminates high frequency components; perform Fourier transform on the low-pass filtered current fundamental wave component and voltage fundamental wave component respectively, and then calculate the current value, voltage value and compensation voltage Value, by comparing the compensation voltage value and the phase of the negative sequence current to determine the transmission line fault distance. The single-end distance measurement method of the transmission line provided by the present invention is not affected by the load current and fault type, and the distance measurement accuracy is significantly better than the existing single-end measurement distance measurement method, and does not require data on the opposite side of the line, and does not require synchronization. Add a new sampling value, and the amount of calculation is small.

Description

A Single-End Ranging Method for Transmission Line Using Negative Sequence Current as Polarization Quantity

technical field

The invention relates to a method in the field of electric power system relay protection, in particular to a single-end ranging method of a transmission line using negative sequence current as the polarization quantity.

Background technique

After a fault occurs on a transmission line, it is necessary to perform fault location for fault location. The calculation formula of the current single-ended distance measurement method adopted by the transmission line is

In the formula, In order to protect the i-phase voltage at the installation place (i=A, B, C), In order to protect the current at the installation place (i=A, B, C), k is the zero-sequence compensation coefficient, and I ₀ is the zero-sequence current.

The ranging method is affected by the load current, and the ranging accuracy is insufficient.

In order to overcome the influence of load current, the zero-sequence current phase of the protection installation is used to replace The distance is measured by using the phase ratio of the compensation voltage and the zero-sequence current, but when a phase-to-phase short circuit occurs, there is no zero-sequence component, so the distance measurement method is affected by the type of fault.

Therefore, it is necessary to provide a method for single-end distance measurement of transmission lines that is not affected by load current and fault type.

Contents of the invention

The object of the present invention is to solve the above-mentioned problems and provide a single-end ranging method of transmission lines with negative sequence current as the polarization quantity, which has the advantage of not being affected by load current and fault type.

In order to achieve the above object, the present invention adopts the following technical solutions:

A single-ended ranging method for a transmission line using negative sequence current as a polarization quantity, comprising the following steps:

Step (1): Obtain the current value and voltage value at the place where the transmission line protection is installed, and perform low-pass filtering on the current value and voltage value to obtain the current fundamental wave component and voltage fundamental wave component that eliminate high-frequency components;

Step (2): Perform Fourier transform on the low-pass filtered current fundamental component and voltage fundamental component to obtain the i-th phase current i phase voltage ij phase current ij phase voltage Phase i negative sequence current and ij phase negative sequence current i=A, B, C; ij=AB, BC, CA;

Step (3): Calculate the i-th phase compensation voltage and ij phase compensation voltage

Step (4): For a single-phase-to-earth fault, for a given line length corresponding to the impedance, compare and the phase of

when and When the two phases are the same, the corresponding Z is the impedance from the protection installation to the fault point, l=Z/Z ₁ , and Z ₁ is the positive sequence impedance of the line per unit length;

when and When the two phases are different, reduce Z until and Both have the same phase; if Z is 0, and If the two phases are still different, stop the calculation, and the meaning of the parameter l is the fault distance.

The i-th phase compensation voltage of the step (3) The calculation method is: The parameter meaning of Z is the setting impedance, The parameter meaning of k is the zero-sequence current, and the parameter meaning of k is the zero-sequence compensation coefficient.

The calculation method of the ij phase compensation voltage of described step (3) is:

A single-ended ranging method for a transmission line using negative sequence current as a polarization quantity, comprising the following steps:

Step (1): Obtain the current value and voltage value at the place where the transmission line protection is installed, and perform low-pass filtering on the current value and voltage value to obtain the current fundamental wave component and voltage fundamental wave component that eliminate high-frequency components;

Step (2): Perform Fourier transform on the low-pass filtered current fundamental component and voltage fundamental component to obtain the i-th phase current i phase voltage ij phase current ij phase voltage Phase i negative sequence current and ij phase negative sequence current i=A, B, C; ij=AB, BC, CA;

Step (3): Calculate the i-th phase compensation voltage and ij phase compensation voltage

Step (4): For a two-phase short circuit, for a given line length corresponding to the impedance, compare and the phase of

when and When the phases of the two are the same, the corresponding Z is the impedance from the protection installation to the fault point, l=Z/Z ₁ , and Z ₁ is the positive sequence impedance of the line per unit length;

when and When the two phases are different, reduce Z until and Both have the same phase; if Z is 0, and If the two phases are still different, stop the calculation.

The i-th phase compensation voltage of the step (3) The calculation method is: The parameter meaning of Z is the setting impedance, The parameter meaning of k is the zero-sequence current, and the parameter meaning of k is the zero-sequence compensation coefficient.

The calculation method of the ij phase compensation voltage of described step (3) is:

This method is suitable for overhead transmission lines

The present invention has the following beneficial effects:

The single-end ranging method of the transmission line provided by the invention is not affected by load current and fault type. The distance measurement accuracy is significantly better than the existing single-ended distance measurement method, and does not require data on the opposite side of the line, does not need to be synchronized, does not need to add new sampling values, and has a small amount of calculation.

Description of drawings

Fig. 1 is a kind of flow chart 1 of single-ended ranging method of transmission line based on negative-sequence current as polarization quantity;

Fig. 2 is a kind of flowchart two of single-ended ranging method of transmission line based on negative sequence current as polarization quantity;

Fig. 3 is a schematic diagram of an embodiment of the present invention.

Detailed ways

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

As shown in Figure 1, a single-ended ranging method for transmission lines with negative sequence current as the polarization quantity includes the following steps:

Step (1): Obtain the current value and voltage value at the place where the transmission line protection is installed, and perform low-pass filtering on the current value and voltage value to obtain the current fundamental wave component and voltage fundamental wave component that eliminate high-frequency components;

Step (2): Perform Fourier transform on the low-pass filtered current fundamental component and voltage fundamental component to obtain the i-th phase current i phase voltage ij phase current ij phase voltage Phase i negative sequence current and ij phase negative sequence current i=A, B, C; ij=AB, BC, CA;

Step (3): Calculate the i-th phase compensation voltage and ij phase compensation voltage

Step (4): For a single-phase-to-earth fault, for a given line length corresponding to the impedance, compare and the phase of

when and When the two phases are the same, the corresponding Z is the impedance from the protection installation to the fault point, l=Z/Z ₁ , and Z ₁ is the positive sequence impedance of the line per unit length;

when and When the two phases are different, reduce Z until and Both have the same phase; if Z is 0, and If the phases of the two are still different, stop the calculation, and the meaning of the parameter l is the fault distance.

The i-th phase compensation voltage of the step (3) The calculation method is: The parameter meaning of Z is the setting impedance, The parameter meaning of k is the zero-sequence current, and the parameter meaning of k is the zero-sequence compensation coefficient.

The calculation method of the ij phase compensation voltage of described step (3) is:

As shown in Figure 2, a single-ended ranging method for transmission lines with negative sequence current as the polarization quantity includes the following steps:

Step (1): Obtain the current value and voltage value at the place where the transmission line protection is installed, and perform low-pass filtering on the current value and voltage value to obtain the current fundamental wave component and voltage fundamental wave component that eliminate high-frequency components;

Step (2): Perform Fourier transform on the low-pass filtered current fundamental component and voltage fundamental component to obtain the i-th phase current i phase voltage ij phase current ij phase voltage Phase i negative sequence current and ij phase negative sequence current i=A, B, C; ij=AB, BC, CA;

Step (3): Calculate the i-th phase compensation voltage and ij phase compensation voltage

Step (4): For a two-phase short circuit, for a given line length corresponding to the impedance, compare and the phase of

when and When the two phases are the same, the corresponding Z is the impedance from the protection installation to the fault point, l=Z/Z ₁ , and Z ₁ is the positive sequence impedance of the line per unit length;

when and When the two phases are different, reduce Z until and Both have the same phase; if Z is 0, and If the two phases are still not the same, stop the calculation.

The i-th phase compensation voltage of the step (3) The calculation method is: The parameter meaning of Z is the setting impedance, The parameter meaning of k is the zero-sequence current, and the parameter meaning of k is the zero-sequence compensation coefficient.

The calculation method of the ij phase compensation voltage of described step (3) is:

The specific embodiment of the present invention will be further described in detail below in conjunction with accompanying drawing 3 .

(1) Phase A ground fault occurs at point F1

1. Obtain the current and voltage values at the installation place of the transmission line protection and carry out low-pass filtering to it;

II. Perform Fourier transform and phase sequence transform to obtain the phasor and negative sequence current

III. Calculation of compensation voltage

IV. Comparison and When the two phases are the same, the corresponding Z is the impedance from the protection installation to the fault point, l=Z/Z ₁ , and Z ₁ is the positive sequence impedance of the line per unit length.

(2) Phase AB short circuit occurs at point F1

1. Obtain the current and voltage values at the installation place of the transmission line protection and carry out low-pass filtering to it;

II. Perform Fourier transform and phase sequence transform to obtain the phasor and negative sequence current

III. Calculation of compensation voltage

IV. Comparison and When the two phases are the same, the corresponding Z is the impedance from the protection installation to the fault point, l=Z/Z ₁ , and Z ₁ is the positive sequence impedance of the line per unit length.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (1)

1. it is a kind of using negative-sequence current as the transmission line of electricity method of single end distance measurement of amount of polarization, it is characterized in that, comprise the following steps：

Step (1)：The current value and voltage value of line protection installation place are obtained, and low pass is carried out to current value and voltage value Filtering, the current first harmonics component for the high fdrequency component that is eliminated and voltage fundamental component；

Step (2)：Fourier transformation is carried out to the current first harmonics component after low-pass filtering and voltage fundamental component, obtains the i-th phase Electric currentI-th phase voltageIj phase currentsIj phase voltagesI phase negative-sequence currentsWith ij phase negative-sequence currentsI=A, B, C；Ij=AB, BC, CA；

Step (3)：Calculate the i-th phase offset voltageAnd ij phase offset voltages

I-th phase offset voltageComputational methods be：

Wherein, the meaning of parameters of Z is to adjust impedance,Meaning of parameters be zero-sequence current, the meaning of parameters of k is zero sequence compensation system Number；

The computational methods of ij phase offset voltages are：

Step (4)：

For singlephase earth fault, for given total track length counterpart impedance, compareWithPhase,

WhenWithWhen the two phase is identical, corresponding Z is protection installation place to the impedance of trouble point, l=Z/Z₁, Z₁For unit Length circuit positive sequence impedance；

WhenWithDuring the two phase difference, Z is reduced by, untilWithThe two phase is identical；If Z is 0,WithThe two Phase still differs, and stops calculating, the meaning of parameters of l is fault distance；

For line to line fault, for given total track length counterpart impedance, compareWithPhase,

WhenWithWhen the two phase is identical, corresponding Z is protection installation place to the impedance of trouble point, l=Z/Z₁, Z₁For unit Length circuit positive sequence impedance；

WhenWithDuring the two phase difference, Z is reduced by, untilWithThe two phase is identical；If Z is 0,WithThe two Phase still differs, and stops calculating.