CN103187719A - Electric transmission line interphase fault full-component voltage protection method - Google Patents

Abstract

The invention discloses an electric transmission line interphase fault full-component voltage protection method. The method realizes electric transmission line interphase short circuit fault full-component voltage protection by utilizing the along-the-line voltage drop distribution characteristic, eliminates the influence of the operating method of the system, transition resistance and load current on the protection action performance, and is suitable for protecting the whole fault process of the electric transmission line interphase fault, wherein the along-the-line voltage drop distribution characteristic is as follows: when the fault occurs in a protection area, the along-the-line voltage drop amplitude from a protection mounting position to an interphase short circuit fault point is less than the voltage drop amplitude from the protection mounting position to a protection setting range; and when the fault occurs outside the protection area, the along-the-line voltage drop amplitude from a protection mounting position to the interphase short circuit fault point is more than the voltage drop amplitude from the protection mounting position to the protection setting range.

Description

Full-component voltage protection method for interphase fault of power transmission line

Technical Field

The invention relates to the technical field of relay protection of power systems, in particular to a full component voltage protection method for interphase fault of a power transmission line.

Background

The transmission line distance protection can be divided into two types, namely, the abrupt variable-based line distance protection and the full component-based line distance protection according to different electrical quantities. The circuit distance protection based on the break variable is little influenced by the system operation mode and has strong transition resistance capability, the reliability of the performance of the protection action is high, but because the electrical break variable only exists in two cycles after the fault, the circuit distance protection based on the break variable can not play a role in relay protection for the circuit fault after the two cycles, and can not be suitable for the protection of the whole fault process of the circuit. Although the line distance protection based on the full component is suitable for the protection of the whole fault process of the line, because the self protection algorithm is seriously influenced by the transition resistance, the protection is easy to reject or malfunction when the high-resistance grounding fault occurs, and the protection reliability is not high.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a full-component voltage protection method for interphase fault of a power transmission line.

A method for protecting all-component voltage of interphase fault of a power transmission line comprises the following steps:

(1) measuring fault phase-to-phase voltage at transmission line protection installation

Phase to phase current of fault

And normal phase negative sequence current

(ii) a Wherein φ = AB, BC, CA phases,

phase = C, A, B.

(2) Calculating the voltage drop from the protection installation position of the power transmission line to the interphase short-circuit fault point

Real part of

And imaginary part

：

$\mathrm{Re}\left(\mathrm{\Δ}{\stackrel{.}{U}}_f\right)=\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)-\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)}{\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\cos \mathrm{\β}-\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\sin \mathrm{\β}}\cos \mathrm{\β}$

$\mathrm{Im}\left(\mathrm{\Δ}{\stackrel{.}{U}}_f\right)=\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)-\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)}{\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\cos \mathrm{\β}-\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\sin \mathrm{\β}}\sin \mathrm{\β}$

Wherein,

is the fault phase interphase voltage;

is fault phase interphase current;

is normal phase negative sequence current; phi = AB, BC, CA phase;

= C, A, B phases; beta is normal phase negative sequence current

A phase angle after 90 degrees of counterclockwise rotation; z is a radical of₁Is the positive sequence of the transmission line with unit length.

(3) Comparison of protection criteria

Whether the current state is established or not, if so, protecting the action, wherein; x is the number of_setTo protect the setting range.

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

the method of the invention utilizes the distribution characteristic of voltage drop along the line, namely when the fault occurs in the protection area, the voltage drop amplitude along the line from the protection installation position to the interphase short-circuit fault point is smaller than the voltage drop amplitude from the protection installation position to the protection setting range; when the fault occurs outside the protection area, the voltage drop amplitude along the line from the protection installation position to the interphase short-circuit fault point is larger than the voltage drop amplitude from the protection installation position to the protection setting range, so that the interphase short-circuit fault full-component voltage protection of the power transmission line is realized, the influence of the system operation mode, the transition resistance and the load current on the protection action performance is eliminated, and the method is suitable for the protection of the whole fault process of the interphase fault of the power transmission line.

Drawings

Fig. 1 is a schematic diagram of a line transmission system to which the present invention is applied.

Detailed Description

The technical scheme of the invention is further detailed in the following description and the accompanying drawings.

In fig. 1, the CVT is a capacitor voltage transformer, and the CT is a current transformer. Protection device measures fault phase-to-phase voltage at protection installation position of power transmission line

Phase to phase current of fault

And normal phase negative sequence current

(ii) a Wherein φ = AB, BC, CA phases,

phase = C, A, B.

Calculating the real part of the voltage drop from the protection installation position of the power transmission line to the interphase short-circuit fault point

And imaginary part

：

$\mathrm{Re}\left(\mathrm{\Δ}{\stackrel{.}{U}}_f\right)=\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)-\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)}{\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\cos \mathrm{\β}-\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\sin \mathrm{\β}}\cos \mathrm{\β}$

$\mathrm{Im}\left(\mathrm{\Δ}{\stackrel{.}{U}}_f\right)=\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)-\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)}{\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\cos \mathrm{\β}-\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\sin \mathrm{\β}}\sin \mathrm{\β}$

Wherein beta is normal phase negative sequence current

A phase angle after 90 degrees of counterclockwise rotation;for fault phase-to-phase voltage

The real part of (a);for fault phase-to-phase voltage

An imaginary part of (d);

is composed of

An imaginary part of (d);is composed of

The real part of (a).

The distribution characteristics of voltage drops along the line after the electric transmission line has an interphase short circuit fault are as follows: when the fault occurs in the protection area, the voltage drop amplitude along the line from the protection installation position to the interphase short-circuit fault point is smaller than the voltage drop amplitude from the protection installation position to the protection setting range; when the fault is generated outside the protection area, the voltage drop amplitude along the line from the protection installation position to the interphase short-circuit fault point is larger than the voltage drop amplitude from the protection installation position to the protection setting range.

Therefore, the protection criteria for the method of the invention are as follows:

$\sqrt{{\left[\mathrm{Re}\left(\mathrm{\&Delta;}{\stackrel{.}{U}}_f\right)\right]}^2+{\left[\mathrm{Im}\left(\mathrm{\&Delta;}{\stackrel{.}{U}}_f\right)\right]}^2}<\left|x_{\mathrm{set}}{z}_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right|$

if it is

If yes, the action is protected. Wherein z is₁Is the positive sequence impedance of the transmission line with unit length.

The method realizes the full-component voltage protection of the interphase fault of the power transmission line by utilizing the distribution characteristic of voltage drop along the line (namely, when the fault occurs in the protection area, the voltage drop amplitude along the line from the protection installation position to the interphase short-circuit fault point is smaller than the voltage drop amplitude from the protection installation position to the protection setting range, and when the fault occurs outside the protection area, the voltage drop amplitude along the line from the protection installation position to the interphase short-circuit fault point is larger than the voltage drop amplitude from the protection installation position to the protection setting range), eliminates the influence of the system operation mode, the transition resistance and the load current on the protection action performance, and is suitable for the protection of the whole fault process of the interphase fault of the power transmission.

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 protecting all-component voltage of interphase fault of a power transmission line comprises the following steps:

(1) measuring fault phase-to-phase voltage at transmission line protection installation

Phase to phase current of fault

And normal phase negative sequence current

(ii) a Wherein φ = AB, BC, CA phases,= C, A, B phase(s) of a liquid,

(2) calculating the voltage drop from the protection installation position of the power transmission line to the interphase short-circuit fault point

Real part of

And imaginary part

：

$\mathrm{Re}\left(\mathrm{\&Delta;}{\stackrel{.}{U}}_f\right)=\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\&phi;\&phi;}}\right)-\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\&phi;\&phi;}}\right)\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\&phi;\&phi;}}\right)\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)}{\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)\cos \mathrm{\&beta;}-\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)\sin \mathrm{\&beta;}}\cos \mathrm{\&beta;}$

$\mathrm{Im}\left(\mathrm{\&Delta;}{\stackrel{.}{U}}_f\right)=\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\&phi;\&phi;}}\right)-\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\&phi;\&phi;}}\right)\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\&phi;\&phi;}}\right)\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)}{\mathrm{Im}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)\cos \mathrm{\&beta;}-\mathrm{Re}\left(z_1{\stackrel{.}{I}}_{\mathrm{\&phi;\&phi;}}\right)\sin \mathrm{\&beta;}}\sin \mathrm{\&beta;}$

Wherein,

is the fault phase interphase voltage;

is fault phase interphase current;

is normal phase negative sequence current; phi = AB, BC, CA phase;= C, A, B phases; beta is normal phase negative sequence current

A phase angle after 90 degrees of counterclockwise rotation; z is a radical of₁Is a positive sequence of the transmission line with unit length,

(3) comparison of protection criteria

Whether the current state is established or not, if so, protecting the action, wherein; x is the number of_setTo protect the setting range.

Images