CN103176102A - Wire single-phase earth fault single-end ranging method using ranging scale minimum principle - Google Patents

Abstract

Line single-phase earth fault single-terminal location method is realized using ranging scale minimum principle the invention discloses a kind of. The faulted phase voltage of line protection installation place is measured first , faulted phase current

, failure phase negative-sequence current

And zero-sequence current

; Then choosing fault distance initial value is lx; gradually increased with step delta l; successively for the ranging scale e (lx) of every bit up to transmission line of electricity overall length, selection ranging scale e (lx) the smallest distance of point away from line protection installation place is fault distance on computing electric power line. The method of the present invention describes the physical characteristic of transmission line of electricity voltage, electric current transmission using distribution parameter, range accuracy is not influenced by transmission line of electricity direct-to-ground capacitance, suitable for any voltage class transmission line one-phase earth fault single end distance measurement, it is particularly suitable for super-pressure, UHV transmission line singlephase earth fault single end distance measurement.

Description

Method for realizing single-phase earth fault single-terminal ranging of line by using minimum ranging scale principle

Technical Field

The invention relates to the technical field of single-ended fault location of a power system, in particular to a method for achieving single-ended location of a line single-phase earth fault by using a minimum distance measurement scale principle.

Background

According to the division of the electrical quantity source, the fault distance measuring method is mainly divided into a double-end distance measuring method and a single-end distance measuring method. The double-end distance measurement method utilizes the electric quantities at two ends of the power transmission line to carry out fault location, needs to obtain the electric quantity at the opposite end through the data transmission channel, has strong dependence on the data transmission channel, and is easily influenced by the synchronism of double-end sampling values in actual use. The ultra-high voltage alternating current transmission line is often a long-distance transmission line, and the laying of a data transmission channel required by ranging requires additional investment of a large amount of capital, so that the single-end ranging method is more practical than the double-end ranging method. The single-end distance measurement method only utilizes the electric quantity at one end of the power transmission line to carry out fault location, does not need communication and data synchronization equipment, has low operation cost and stable algorithm, and is widely applied to high, medium and low voltage power transmission lines.

Currently, the single-ended distance measurement method is mainly classified into a traveling wave method and an impedance method. The traveling wave method utilizes the transmission property of fault transient traveling waves to carry out single-end fault location, has high precision, is not influenced by an operation mode, excessive resistance and the like, has high requirement on the sampling rate, needs a special wave recording device and has high application cost. The impedance method calculates the impedance of a fault loop by using the voltage and the current after the fault, performs single-end fault location according to the characteristic that the line length is in direct proportion to the impedance, is simple and reliable, but the location precision is seriously influenced by factors such as transition resistance, load current and the like, and particularly when the transition resistance is large, the location result of the impedance method can be seriously deviated from the real fault distance, and even the location failure occurs. Because large distributed capacitance current exists along the ultrahigh voltage and ultrahigh voltage transmission lines, when the ultrahigh voltage and ultrahigh voltage transmission lines have medium-high resistance short circuit faults, the single-ended impedance method distance measurement result can be seriously deviated from the real fault distance, and the field application requirements can not be met. Therefore, the single-ended impedance method adopting the lumped parameter modeling cannot be directly applied to the single-ended fault location of the ultra-high voltage and ultra-high voltage transmission lines.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a method for realizing single-phase earth fault single-terminal distance measurement of a line by using a principle of minimum distance measurement scale, which can overcome the influence of transition resistance and load current on the distance measurement precision, and has the advantages of high distance measurement precision, simple distance measurement principle and strong practicability.

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

(1) protection device measures fault phase voltage at protection installation position of power transmission line

Phase current of fault

Fault phase negative sequence current

And zero sequence current

(ii) a Wherein φ = A phase, B phase, C phase.

(2) The initial value of the fault distance is taken as l_xCalculating distance to protective installation position l of power transmission line_xDistance measurement scale e (l) of points_x)：

$e\left(l_x\right)=\left|\right|Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_x\right)|-|\frac{{\stackrel{.}{U}}_{\mathrm{\φ}}}{{\stackrel{.}{I}}_{\mathrm{\φ}}+\left(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right){\stackrel{.}{I}}_0}\frac{\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\left|\right|$

Wherein phi = A phase, B phase, C phase;

is a fault phase voltage;

is the fault phase current;

is a fault phase negative sequence current;

is zero sequence current; l_setProtecting the setting range; z₀Zero sequence equivalent impedance of a system at the protection installation position of the power transmission line; gamma ray₁、γ₀Respectively are transmission line positive sequence and zero sequence transmission coefficients; z_c1、Z_c0Respectively positive sequence wave impedance and zero sequence wave impedance of the power transmission line; α = Arg (Z)_c1(γ₁l_set))；

； $\mathrm{\γ}=\mathrm{Arg}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{.}{I}}_0}{{\stackrel{.}{I}}_{\mathrm{\φ}2}}\right)$ (ii) a th () is a hyperbolic tangent function; ch (.) is a hyperbolic cosine function; sh () is a hyperbolic sine function.

(3) The fault distance is gradually increased by the step length delta l, the step (2) is returned, and the distance measurement scale e (l) of each point on the transmission line is calculated in sequence_x) Selecting a distance measurement scale e (l) until the full length of the power transmission line_x) The distance between the minimum point and the protective installation position of the power transmission line is the fault distance.

In summary, compared with the prior art, the invention has the following advantages:

the method adopts the distribution parameters to describe the physical characteristics of the voltage and current transmission of the transmission line, the distance measurement precision is not influenced by the ground capacitance of the transmission line, and the method is suitable for single-phase ground fault single-terminal distance measurement of the transmission line of any voltage class, and is particularly suitable for single-phase ground fault single-terminal distance measurement of the ultra-high voltage and ultra-high voltage transmission lines. The method carries out single-end distance measurement of the single-phase earth fault of the power transmission line according to the principle that the distance measurement scale corresponding to the fault point is minimum, overcomes the influence of transition resistance and load current on the distance measurement precision, and has the advantages of high distance measurement precision, simple distance measurement principle and strong practicability.

Drawings

FIG. 1 is a schematic diagram of a single-phase earth fault of a power transmission line to which the method of the present invention is applied;

fig. 2 is an electric vector diagram of the single-phase earth fault of the power transmission line applying the method of the invention.

Detailed Description

The technical solution of the present invention will be described in further detail with reference to the following examples.

In fig. 1, TV is a voltage transformer and TA is a current transformer. After the power transmission line has single-phase earth fault, the protection device measures the fault phase voltage at the protection installation position of the power transmission line

Phase current of fault

Fault phase negative sequence current

And zero sequence current

(ii) a Wherein φ = A phase, B phase, C phase.

Single-phase resistance R of power transmission line_gEarth fault, earth fault point voltage

Branch current of earth fault

Because of resistive earth faults, in the earth-fault branchThereby satisfying

。

In the branch circuit with ground faultAnd

thus having

. Wherein,

、

、

respectively positive sequence current, negative sequence current and zero sequence current flowing through the ground fault branch circuit.

Due to fault phase negative sequence current at transmission line protection installation

Negative sequence current to ground fault branch

In phase, thereby obtaining $\mathrm{Arg}\left({\stackrel{.}{I}}_{\mathrm{\φ}2}\right)=\mathrm{Arg}\left({\stackrel{.}{U}}_{\mathrm{\φf}}\right)$ 。

Profiling using distributed parametric modelsThe fault phase voltage at the protection installation position of the power transmission line

Phase current of fault

Zero sequence currentAnd ground fault point voltage

The relationship (c) is as described in formula (1).

${\stackrel{.}{U}}_{\mathrm{\φ}}=\frac{{\stackrel{.}{U}}_{\mathrm{\φf}}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_f\right)}+Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_f\right)[{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_f\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_f\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_f\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_f\right)}-1){\stackrel{.}{I}}_0]---\left(1\right)$

Wherein φ = A phase or B phase or C phase; l_fFor single-phase earth fault point of transmission lineFault distance to protective installation;

is the ground fault point voltage; gamma ray₁The transmission line positive sequence propagation coefficient is as follows:，R₁、L₁、G₁、C₁respectively is the positive sequence resistance, inductance, conductance and capacitance of the transmission line of unit length;

γ₀the zero sequence propagation coefficient of the power transmission line is as follows:

，R₀、L₀、G₀、C₀zero sequence resistance, inductance, conductance and capacitance of the transmission line of unit length respectively;

Z_c1the positive sequence wave impedance of the power transmission line:

；

Z_c0zero-sequence wave impedance of the power transmission line:

；

omega is a rated angular frequency value of the power system;

Z₀zero sequence equivalent impedance of a system at the protection installation position of the power transmission line;

th () is a hyperbolic tangent function; ch (.) is a hyperbolic cosine function; sh () is a hyperbolic sine function.

Zero sequence current compensation coefficient due to single-phase earth fault point

And protection setting range l_setZero sequence current compensation coefficient ofApproximately equal, equation (1) may be equivalent to equation (2).

${\stackrel{.}{U}}_{\mathrm{\φ}}=\frac{{\stackrel{.}{U}}_{\mathrm{\φf}}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_f\right)}+Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_f\right)[{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{.}{I}}_0]---\left(2\right)$

Wherein l_setTo protect the setting range.

Fig. 2 is an electric vector diagram of the single-phase earth fault of the power transmission line applying the method of the invention. As shown in FIG. 2, from

、

And

and in the formed vector relation triangle, the relation of the formula (3) is obtained according to the corner relation of the triangle.

$|-Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_f\right)[{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{.}{I}}_0\left]\right|=\left|\frac{{\stackrel{.}{U}}_{\mathrm{\φ}}\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\right|---\left(3\right)$

Wherein φ = A phase or B phase or C phase;

l_setprotecting the setting range;

alpha is Z_c1th(γ₁l_set) Angle of (a = Arg) (Z)_c1th(γ₁l_set))；

Z₀Zero sequence equivalent impedance of a system at the protection installation position of the power transmission line;

beta is

Lead ahead

The angle of (a) is determined,

；

gamma is

Lead ahead

The angle of (a) is determined,

$\mathrm{\γ}=\mathrm{Arg}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{.}{I}}_0}{{\stackrel{.}{I}}_{\mathrm{\φ}2}}\right)$ 。

due to the fact that $|-Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_f\right)[{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{.}{I}}_0\left]\right|=$ $|Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_f\right)|\×|{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{.}{I}}_0|$ Therefore, the fault impedance amplitude value | Z of the single-phase earth fault of the power transmission line is obtained_c1th(γ₁l_f) Equation (4) for | is calculated.

$\left|Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_f\right)\right|=\left|\frac{{\stackrel{.}{U}}_{\mathrm{\φ}}}{{\stackrel{.}{I}}_{\mathrm{\φ}}+\left(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right){\stackrel{.}{I}}_0}\frac{\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\right|---\left(4\right)$

Then, the initial value of the fault distance is taken as l_xCalculating distance to protective installation position l of power transmission line_xDistance measurement scale e (l) of points_x)：

$e\left(l_x\right)=\left|\right|Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_x\right)|-|\frac{{\stackrel{.}{U}}_{\mathrm{\φ}}}{{\stackrel{.}{I}}_{\mathrm{\φ}}+\left(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right){\stackrel{.}{I}}_0}\frac{\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\left|\right|---\left(5\right)$

The fault distance is gradually increased by the step length delta l, and the distance measurement scale e (l) of each point on the transmission line is calculated in sequence by repeatedly using the formula (5)_x) Selecting a distance measurement scale e (l) until the full length of the power transmission line_x) The distance between the minimum point and the protective installation position of the power transmission line is the fault distance.

The method adopts the distribution parameters to describe the physical characteristics of the voltage and current transmission of the transmission line, the distance measurement precision is not influenced by the ground capacitance of the transmission line, and the method is suitable for single-phase ground fault single-terminal distance measurement of the transmission line of any voltage class, and is particularly suitable for single-phase ground fault single-terminal distance measurement of the ultra-high voltage and ultra-high voltage transmission lines. The method carries out single-end distance measurement of the single-phase earth fault of the power transmission line according to the principle that the distance measurement scale corresponding to the fault point is minimum, overcomes the influence of transition resistance and load current on the distance measurement precision, and has the advantages of high distance measurement precision, simple distance measurement principle and strong practicability.

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)

1. A method for realizing single-phase earth fault single-terminal ranging of a line by using a ranging scale minimum principle is characterized by comprising the following steps of: comprises the following steps:

(1) protection device measures fault phase voltage at protection installation position of power transmission line

Phase current of fault

Negative phase of failureSequence current

And zero sequence current

(ii) a Wherein φ = A phase, B phase, C phase,

(2) the initial value of the fault distance is taken as l_xCalculating distance to protective installation position l of power transmission line_xDistance measurement scale e (l) of points_x)：

$e\left(l_x\right)=\left|\right|Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_x\right)|-|\frac{{\stackrel{.}{U}}_{\mathrm{\φ}}}{{\stackrel{.}{I}}_{\mathrm{\φ}}+\left(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right){\stackrel{.}{I}}_0}\frac{\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\left|\right|$

Wherein phi = A phase, B phase, C phase;

is a fault phase voltage;

is the fault phase current;

is a fault phase negative sequence current;

is zero sequence current; l_setProtecting the setting range; z₀Zero sequence equivalent impedance of a system at the protection installation position of the power transmission line; gamma ray₁、γ₀Respectively are transmission line positive sequence and zero sequence transmission coefficients; z_c1、Z_c0Respectively positive sequence wave impedance and zero sequence wave impedance of the power transmission line; α = Arg (Z)_c1th(γ₁l_set))；

； $\mathrm{\γ}=\mathrm{Arg}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{.}{I}}_0}{{\stackrel{.}{I}}_{\mathrm{\φ}2}}\right)$ (ii) a th () is a hyperbolic tangent function; ch (.) is a hyperbolic cosine function; sh () is a hyperbolic sine function,

(3) the fault distance is gradually increased by the step length delta l, the step (2) is returned, and the distance measurement scale e (l) of each point on the transmission line is calculated in sequence_x) Selecting a distance measurement scale e (l) until the full length of the power transmission line_x) The distance between the minimum point and the protective installation position of the power transmission line is the fault distance.

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