CN104950220A

CN104950220A - Double-circuit-on-same-tower double-circuit line single-phase grounding fault single-end distance measurement method implemented by using single-end electrical quantity of single-circuit line

Info

Publication number: CN104950220A
Application number: CN201510336606.7A
Authority: CN
Inventors: 曾惠敏
Original assignee: State Grid Corp of China SGCC; State Grid Fujian Electric Power Co Ltd; Maintenance Branch of State Grid Fujian Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; State Grid Fujian Electric Power Co Ltd; Maintenance Branch of State Grid Fujian Electric Power Co Ltd
Priority date: 2015-06-17
Filing date: 2015-06-17
Publication date: 2015-09-30
Anticipated expiration: 2035-06-17
Also published as: CN104950220B

Abstract

The invention discloses a double-circuit-on-same-tower double-circuit line single-phase grounding fault single-end distance measurement method implemented by using the single-end electrical quantity of a single-circuit line. A fixed step length is increased gradually in sequence from the protection mounting position of the I-circuit line of the double-circuit-on-same-tower double-circuit line by adopting a one-dimensional searching method so as to calculate phase angles of negative-sequence current of an operating voltage leading fault phase at each point of the I-circuit line of the double-circuit-on-same-tower double-circuit line until the full length of the I-circuit line of the double-circuit-on-same-tower double-circuit line is completed; the phase angle of the negative-sequence current of the operating voltage leading fault phase at a certain point is dropped within the range of (0 degree, 180 degrees), and the phase angle of the negative-sequence current of the operating voltage leading fault phase at the next adjacent point is dropped within the range of (180 degrees, 360 degrees), so that the middle position between the two points is a fault point. According to the method, the influence of the interline zero-sequence mutual inductance is metered, so that the influence of the interline zero-sequence mutual inductance on the single-end distance measuring precision of the single-phase grounding fault of the double-circuit-on-same-tower double-circuit line is eliminated.

Description

Method for realizing single-phase earth fault single-end distance measurement of double-circuit lines on same tower by using single-end electric quantity of single-circuit line

Technical Field

The invention relates to the technical field of power system relay protection, in particular to a method for realizing single-phase earth fault single-end distance measurement of double-circuit lines on the same tower by using single-end electric quantity of a single-circuit line.

Background

The method is divided from the electric quantity used for ranging, and the fault ranging method can be divided into two main categories: double-ended ranging and single-ended ranging. The double-end fault location method is a method for determining the fault position of the power transmission line by utilizing the electric quantities at two ends of the power transmission line, and the electric quantity at the opposite end needs to be obtained through a channel, so that the dependence on the channel is strong, and the method is also easily influenced by the synchronism of double-end sampling values in actual use. The single-ended distance measurement method is a method for determining the fault position of the power transmission line by only using voltage and current data at one end of the power transmission line, and is widely applied to medium and low voltage lines because only one end of data is needed, communication and data synchronization equipment is not needed, the operation cost is low, and the algorithm is stable. Currently, the single-ended distance measurement method is mainly divided into two types, one is a traveling wave method, and the other is an impedance method. The traveling wave method utilizes the transmission property of fault transient traveling waves to carry out distance measurement, has high precision, is not influenced by an operation mode, excess resistance and the like, has high requirement on the sampling rate, needs a special wave recording device and is not substantially applied at present. The impedance method utilizes the voltage and the current after the fault to calculate the impedance of the fault loop, and carries out distance measurement according to the characteristic that the line length is in direct proportion to the impedance, the distance measurement principle is simple and reliable, but when the impedance method is applied to single-phase earth fault single-end fault distance measurement of double-circuit lines on the same tower, the distance measurement precision is seriously influenced by the transition resistance of the fault point and zero sequence mutual inductance between lines. Zero sequence mutual inductance exists between double-circuit lines on the same tower, and the zero sequence mutual inductance can influence a zero sequence compensation coefficient, so that the error of the ranging result of the impedance method is large. If single-phase high-resistance grounding faults occur in double-circuit lines on the same tower, the single-phase high-resistance grounding faults are comprehensively influenced by zero sequence mutual inductance and high transition resistance between lines, the distance measurement result of an impedance method often exceeds the full length of the lines or does not have the distance measurement result, accurate fault position information cannot be provided, line fault line inspection is difficult, and quick fault discharge and quick line power supply recovery are not facilitated.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a method for realizing single-phase earth fault single-end distance measurement of double-circuit lines on the same tower by using single-end electric quantity of a single-circuit line, wherein the measurement precision of the method is not influenced by factors such as zero sequence mutual inductance between lines, load current, transition resistance, fault position and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

the method for realizing single-phase earth fault single-end distance measurement of the double-circuit lines on the same tower by using the single-end electric quantity of the single-circuit line is characterized by comprising the following sequential steps:

(1) the protection device measures the fault phase voltage at the protection installation position of the I-loop circuit of the double-loop circuit on the same towerFault phase currentFault phase negative sequence currentAnd zero sequence currentWherein phi is an I loop circuit A phase, an I loop circuit B phase and an I loop circuit C phase;

(2) the protection device selects the initial value of the fault distance as l_xCalculating zero sequence current of II-loop circuit of double-loop circuit on the same tower

Wherein Z is_m0The equivalent impedance of a zero sequence system at the protection installation position of the same-tower double-circuit line I return line side; z_n0The equivalent impedance of a zero sequence system at the protection installation position at the opposite side of the I-loop circuit of the double-loop circuit on the same tower is obtained; z_mZero sequence mutual inductance between the circuit I of the double-circuit line on the same tower and the circuit II of the double-circuit line on the same tower is achieved; l is the length of the I loop of the double-loop line on the same tower; z_I0Zero sequence impedance of I-loop circuit of double-loop circuit on the same tower;

(3) i-loop protection installation position l of double-loop line on same tower with calculated distance_xOperating voltage of point

Wherein Z is_I0Zero sequence impedance of I-loop circuit of double-loop circuit on the same tower; z_I1The positive sequence impedance of the I-loop line of the double-loop line on the same tower is obtained; phi is an I loop line A phase, an I loop line B phase and an I loop line C phase; z_mZero sequence mutual inductance between the circuit I of the double-circuit line on the same tower and the circuit II of the double-circuit line on the same tower is achieved; l is the length of the I loop of the double-loop line on the same tower;

(4) i-loop protection installation position l of double-loop line on same tower with calculated distance_xOperating voltage of pointLeading fault phase negative sequence currentPhase angle of (l)_x) (ii) a Wherein phi is an I loop circuit A phase, an I loop circuit B phase and an I loop circuit C phase;

(5) initial value of fault distance_xIncreasing by a fixed step length delta l, returning to the step (2), and sequentially calculating the action voltage of each point on the I-loop circuit of the double-loop circuit on the same towerLeading fault phase negative sequence currentPhase angle of (l)_x) Until the total length of the I-loop circuit of the double-loop circuit on the same tower is reached; wherein, the fixed step length delta l is 0.001l, and l is the length of the I loop of the double-loop line on the same tower;

(6) selecting a certain loop on the I-loop of the double-loop line on the same tower_xPoint operating voltageLeading fault phase negative sequence currentPhase angle of (l)_x) Falls within the range of (0 DEG, 180 DEG), and has an operating voltage at the next point adjacent theretoLeading fault phase negative sequence currentPhase angle of (l)_x+ delta l) falls within the range of (180 degrees and 360 degrees), and the middle position of the two points is a single-phase grounding fault point of the I-loop circuit of the double-circuit line on the same tower; wherein,

the invention has the characteristics and technical achievements that:

the method comprises the steps of firstly measuring fault phase voltage, fault phase current, fault phase negative sequence current and zero sequence current at the protection installation position of a double-circuit line I on the same pole, calculating the zero sequence current of a double-circuit line II on the same pole by utilizing the fault phase electric quantity at the protection installation position of the double-circuit line I on the same pole, then adopting a one-dimensional search method, starting from the protection installation position of the double-circuit line I on the same pole, sequentially increasing by fixed step length, sequentially calculating the phase angle of the action voltage lead-ahead fault phase negative sequence current at each point on the circuit line I on the same pole until the whole length of the circuit line I on the same pole, selecting the phase angle of the action voltage lead-ahead fault phase negative sequence current at a certain point on the circuit line I on the same pole to be within the range of (0 DEG and 180 DEG), and selecting the phase angle of the action voltage lead-ahead fault phase negative sequence current at the next point to be within the range of (180 DEG, and in the range of 360 degrees, the middle position of the two points is a fault point. The method of the invention takes the influence of zero sequence mutual inductance between lines into account, and eliminates the influence of the zero sequence mutual inductance between the lines on the single-phase earth fault single-end distance measurement precision of the double-circuit lines on the same tower; the method provided by the invention considers the influence of the voltage of the single-phase earth fault point in the algorithm model, eliminates the influence of the transition resistance on the single-phase earth fault single-terminal distance measurement precision of the double-circuit line on the same tower, and has very high distance measurement precision.

Drawings

Fig. 1 is a schematic diagram of a double-circuit power transmission system on the same tower and with the application of the invention.

Detailed Description

Fig. 1 is a schematic diagram of a double-circuit power transmission system on the same tower and with the application of the invention. In fig. 1, PT is a voltage transformer, CT is a current transformer, and m and n are numbers of two ends of a double-circuit line on the same tower. The protection device measures the fault phase voltage at the protection installation position of the I-loop circuit of the double-loop circuit on the same towerFault phase currentFault phase negative sequence currentAnd zero sequence currentWherein, phi is I loop circuit A phase, I loop circuit B phase, I loop circuit C phase.

Selecting fault distance initial by protection deviceA value of l_xCalculating zero sequence current of II-loop circuit of double-loop circuit on the same tower

Wherein Z is_m0The equivalent impedance of a zero sequence system at the protection installation position of the same-tower double-circuit line I return line side; z_n0The equivalent impedance of a zero sequence system at the protection installation position at the opposite side of the I-loop circuit of the double-loop circuit on the same tower is obtained; z_mZero sequence mutual inductance between the circuit I of the double-circuit line on the same tower and the circuit II of the double-circuit line on the same tower is achieved; l is the length of the I loop of the double-loop line on the same tower; z_I0The zero sequence impedance of the I-loop circuit of the double-loop circuit on the same tower is shown.

I-loop protection installation position l of double-loop line on same tower with calculated distance_xOperating voltage of point

Wherein Z is_I0Zero sequence impedance of I-loop circuit of double-loop circuit on the same tower; z_I1The positive sequence impedance of the I-loop line of the double-loop line on the same tower is obtained; phi is an I loop line A phase, an I loop line B phase and an I loop line C phase; z_mZero sequence mutual inductance between the circuit I of the double-circuit line on the same tower and the circuit II of the double-circuit line on the same tower is achieved; l is the length of the I loop of the double-loop line on the same tower.

I-loop protection installation position l of double-loop line on same tower with calculated distance_xOperating voltage of pointLeading fault phase negative sequence currentPhase angle ofWherein, phi is I loop circuit A phase, I loop circuit B phase, I loop circuit C phase.

Initial value of fault distance_xSequentially calculating the action voltage of each point on the I-loop circuit of the double-loop circuit on the same tower by increasing the fixed step length delta lLeading fault phase negative sequence currentPhase angle of (l)_x) Until the total length of the I-loop circuit of the double-loop circuit on the same tower is reached; wherein, the fixed step length delta l is 0.001l, and l is the length of the I-shaped circuit of the double-circuit on the same tower.

Selecting a certain loop on the I-loop of the double-loop line on the same tower_xPoint operating voltageLeading fault phase negative sequence currentPhase angle of (l)_x) Falls within the range of (0 DEG, 180 DEG), and has an operating voltage at the next point adjacent theretoLeading fault phase negative sequence currentPhase angle ofFalling within the range of (180 degrees and 360 degrees), the middle position of the two points is the same rodErecting a single-phase grounding fault point of a double-circuit I circuit; wherein,

the method comprises the steps of firstly measuring fault phase voltage, fault phase current, fault phase negative sequence current and zero sequence current at the protection installation position of a double-circuit line I on the same pole, calculating the zero sequence current of a double-circuit line II on the same pole by utilizing the fault phase electric quantity at the protection installation position of the double-circuit line I on the same pole, then adopting a one-dimensional search method, starting from the protection installation position of the double-circuit line I on the same pole, sequentially increasing by fixed step length, sequentially calculating the phase angle of the action voltage lead-ahead fault phase negative sequence current at each point on the circuit line I on the same pole until the whole length of the circuit line I on the same pole, selecting the phase angle of the action voltage lead-ahead fault phase negative sequence current at a certain point on the circuit line I on the same pole to be within the range of (0 DEG and 180 DEG), and selecting the phase angle of the action voltage lead-ahead fault phase negative sequence current at the next point to be within the range of (180 DEG, and in the range of 360 degrees, the middle position of the two points is the single-phase grounding fault point of the I-loop of the double-loop line on the same tower. The method of the invention takes the influence of zero sequence mutual inductance between lines into account, and eliminates the influence of the zero sequence mutual inductance between the lines on the single-phase earth fault single-end distance measurement precision of the double-circuit lines on the same tower; the method provided by the invention considers the influence of the voltage of the single-phase earth fault point in the algorithm model, eliminates the influence of the transition resistance on the single-phase earth fault single-terminal distance measurement precision of the double-circuit line on the same tower, and has very high distance measurement precision.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. The method for realizing single-phase earth fault single-end distance measurement of the double-circuit lines on the same tower by using the single-end electric quantity of the single-circuit line comprises the following steps in sequence:

Wherein Z is_I0Zero sequence impedance of I-loop circuit of double-loop circuit on the same tower; z_I1The positive sequence impedance of the I-loop line of the double-loop line on the same tower is obtained; phi is an I loop line A phase, an I loop line B phase and an I loop line C phase; z_mFor double-circuit I-circuit on the same towerZero sequence mutual inductance with a double-circuit line II on the same tower; l is the length of the I loop of the double-loop line on the same tower;