CN101593971B - Failure resonant frequency based protection method - Google Patents

Abstract

The invention discloses a failure resonant frequency based protection method, which comprises failure phase selection and protection criterion. A failure type is judged and a failure phase is indentified by calculating spectral correlation and current spectral energy among A-phase current, a B-phase current and C-phase current of the single side of a transmission line after failure, and the spectral correlation of the failure phase current of both sides of the transmission line is calculated on the basis of the failure type and the failure phase. If the spectral correlation is greater than a setting value, the failure is judged as the failure outside of the region; and on the contrary, the failure is judged as the failure inside the region. After using the protection method, the action of the protection can be less than 10ms without being influenced by system oscillation and load current. The failure resonant frequency based protection method is favorable for removing the failure quickly and reliably and improving the reliability of power supply, and the protection method is also favorable for the stabilization and the safety of an electric power system.

Description

A kind of guard method based on failure resonant frequency

Technical field

The invention belongs to the Power System and its Automation technical field, relate to a kind of relay protecting method particularly.

Technical background

On super, ultra high voltage long-distance transmission line, be to guarantee the power system safety and stability operation, the rapidity of relaying protection is proposed strict requirement, claimed operate time is in 20ms.Because it is bigger to have the transmission line distributed capacitance of bundle conductor; effective resistance is very little; when circuit is short-circuited fault; the damping time constant of network is bigger; the decay of the transient state component of electric current, voltage is very slow during short circuit; transient process will continue one long period, and relaying protection will will be born the influence of various transient currents inevitably, and the protective relaying device that extensively adopts is based on the protection philosophy of 50Hz power frequency amount at present.

In order to reduce the influence of transient state component to protection, based on the protection of power frequency amount the filtering link need be set, but this filtering transient state component fully, the sensitivity that influence is protected; Extensively adopt complete Zhou Fu's formula algorithm and half cycle Fu formula algorithm to extract the power frequency electric parameters at present, desired data window length is at least 10ms, has influenced the responsiveness of protection.

Summary of the invention

The objective of the invention is to have proposed a kind of guard method based on failure resonant frequency in order to overcome above-mentioned defective.The present invention is specifically by the following technical solutions:

A kind of guard method based on failure resonant frequency is characterized in that, described method comprises step:

(1) circuit one side A, B, C three-phase current and the zero-sequence current of collection protective device installation place, by difference algorithm filtering aperiodic component, the frequency spectrum degree of correlation between calculating A, B, the C three-phase current and the spectrum energy of three-phase current;

(2) when circuit is short-circuited fault, zero-sequence current and the zero-sequence current setting value gathered are compared, if described zero-sequence current is greater than this zero-sequence current setting value, then be judged as circuit generation earth fault, if zero-sequence current, then is judged as circuit generation phase fault less than setting value;

(3), judge earth fault phase or phase fault phase according to the frequency spectrum degree of correlation between described A, B, the C three-phase current and the spectrum energy of three-phase current.

For earth fault, if in the three-phase current frequency spectrum degree of correlation, A, B biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, B biphase current is judged as the AB double earthfault greater than the spectrum energy of C phase current; If in the three-phase current frequency spectrum degree of correlation, B, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of B, C biphase current is judged as the BC double earthfault greater than the spectrum energy of A phase current; If in the three-phase current frequency spectrum degree of correlation, A, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, C biphase current is judged as the AC double earthfault greater than the spectrum energy of B phase current.

For earth fault, if in the three-phase current frequency spectrum degree of correlation, A, B biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, B biphase current is judged as C phase earth fault less than the spectrum energy of C phase current; If in the three-phase current frequency spectrum degree of correlation, B, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of B, C biphase current is judged as A phase earth fault less than the spectrum energy of A phase current; If in the three-phase current frequency spectrum degree of correlation, A, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, C biphase current is judged as the B double earthfault less than the spectrum energy of B phase current.

For phase fault, if A, B, the C three-phase current frequency spectrum degree of correlation all greater than current spectrum degree of correlation setting value, are judged as three phase short circuit fault; If only A, the B biphase current frequency spectrum degree of correlation are judged as the AB two-phase short-circuit fault greater than current spectrum degree of correlation setting value; If only B, the C biphase current frequency spectrum degree of correlation are judged as the BC two-phase short-circuit fault greater than current spectrum degree of correlation setting value; If only A, the C biphase current frequency spectrum degree of correlation are judged as the AC two-phase short-circuit fault greater than current spectrum degree of correlation setting value;

The circuit one side ABC three-phase current spectrum energy and the current spectrum degree of correlation are determined by following formula (1) and (2).

$E\left(X\right)=\underset{n=0}{\overset{N}{\mathrm{\Σ}}}{x}^2\left(n\right)---\left(1\right)$

Wherein: E (X)---current spectrum energy, X are respectively A, B, C;

X (n)---current spectrum discrete sampling point, x is respectively A, B, C;

N---sampled point number.

${\mathrm{\ρ}}_{\mathrm{xy}}=\frac{\underset{n=0}{\overset{N}{\mathrm{\Σ}}}x\left(n\right)y\left(n\right)}{\max (E\left(X\right),E\left(Y\right))}\·\frac{\min (E\left(X\right),E\left(Y\right))}{\max (E\left(X\right),E\left(Y\right))}---\left(2\right)$

Wherein: ρ _Xy---the current spectrum degree of correlation, x, y are respectively A, B, C;

E (X)---current spectrum energy, X are respectively A, B, C;

E (Y)---current spectrum energy, Y are respectively A, B, C;

X (n)---current spectrum discrete sampling point, x is respectively A, B, C;

Y (n)---current spectrum discrete sampling point, y is respectively A, B, C;

N---sampled point number.

On the basis of Fault Identification, the frequency spectrum degree of correlation between the fault phase current of computational scheme both sides is if greater than the second current spectrum degree of correlation setting value, be judged as external area error; If, be judged as troubles inside the sample space less than the second current spectrum degree of correlation setting value.

Frequency spectrum relatedness computation formula between the fault phase current of circuit both sides is determined by formula (3).

${\mathrm{\ρ}}_{X{X}^{\′}}=\frac{\underset{n=0}{\overset{N}{\mathrm{\Σ}}}x\left(n\right)x^{\′}\left(n\right)}{\max (E\left(X\right),E\left(X^{\′}\right))}\·\frac{\min (E\left(X\right),E\left(X^{\′}\right))}{\max (E\left(X\right),E\left(X^{\′}\right))}---\left(3\right)$

Wherein: ρ _{XX '}---the frequency spectrum degree of correlation between the fault phase current of circuit both sides, X, X ' are respectively A, B, C;

X (n)---circuit 1 side fault phase current frequency spectrum discrete sampling point, x is respectively A, B, C;

X ' is (n)---the corresponding fault phase current of circuit opposite side frequency spectrum discrete sampling point, and x ' is respectively A, B, C;

E (X)---circuit one side fault phase current spectrum energy, X is respectively A, B, C;

E (X ')---the corresponding fault phase current of circuit opposite side spectrum energy, X ' is respectively A, B, C;

N---sampled point number.

Guard method based on failure resonant frequency disclosed by the invention is not subjected to the influence of system oscillation and load current, very helps quickly and reliably excising fault, help the stable of electric power system and safely, help improving the reliability of power supply.

Description of drawings

Fig. 1 is based in the guard method of failure resonant frequency and selects the phase flow chart about fault;

Fig. 2 is based on troubles inside the sample space criterion flow chart in the guard method of failure resonant frequency.

Embodiment

Also in conjunction with specific embodiments the present invention's technical scheme required for protection is elaborated according to Figure of description below.

Select the phase basic principle as follows based on the fault of failure resonant frequency:

When circuit is short-circuited fault, can produce a large amount of transient state components, and the transient high frequency component shows as the form of resonance frequency on frequency domain, and when earth fault took place, zero-sequence current was bigger, for single phase ground fault, owing to have electromagnetic coupled between the transmission line, if the coupling coefficient between the three-phase line equates, the transient state component frequency spectrum that two non-faults are sensed on mutually is identical, the current spectrum degree of correlation is 1, and the current spectrum energy of fault phase is greater than the current spectrum energy of non-fault phase; For double earthfault, the two non-fault phase current frequency spectrum degrees of correlation are bigger, and the current spectrum energy of fault phase is greater than the current spectrum energy of non-fault phase.When phase fault took place, zero-sequence current approached 0, and during line to line fault, the two fault phase current frequency spectrum degrees of correlation are near 1, and the current spectrum degree of correlation between fault phase and the non-fault phase is near 0; During three-phase shortcircuit, A, B, the C three-phase current frequency spectrum degree of correlation are all bigger.According to above feature, constitute and select facies principle based on the fault of failure resonant frequency.

Protection criterion principle based on failure resonant frequency is as follows:

During circuit generation external area error, flowing through the passing through property of electric current of circuit both sides, is same electric current, so the current spectrum degree of correlation of the corresponding fault phase in circuit both sides is near 1; During troubles inside the sample space, the current difference that flows through the circuit both sides is very big, so the current spectrum degree of correlation of the corresponding fault phase in circuit both sides is much smaller than 1; According to the protection criterion principle of above feature formation based on failure resonant frequency.

The present invention adopts following technical scheme:

A kind of guard method based on failure resonant frequency is characterized in that, described method comprises step:

(1) circuit one side A, B, C three-phase current and the zero-sequence current of collection protective device installation place, by difference algorithm filtering aperiodic component, the frequency spectrum degree of correlation between calculating A, B, the C three-phase current and the spectrum energy of three-phase current;

(2) when circuit is short-circuited fault, zero-sequence current and the zero-sequence current setting value gathered are compared, if described zero-sequence current is greater than this zero-sequence current setting value, then be judged as circuit generation earth fault, if zero-sequence current, then is judged as circuit generation phase fault less than setting value;

(3), judge earth fault phase or phase fault phase according to the frequency spectrum degree of correlation between described A, B, the C three-phase current and the spectrum energy of three-phase current.

According to Figure of description technique scheme is further described below.

Fig. 1 is that the fault that the present invention is based in the failure resonant frequency guard method is selected the phase flow chart.As shown in Figure 1, described fault based on failure resonant frequency selects the phase flow process to comprise:

Gather circuit one side A, B, C three-phase current (I _A, I _B, I _C) and zero-sequence current (I ₀), through difference algorithm filtering aperiodic component, calculate I _A, I _B, I _CFrequency spectrum, calculate I then _A, I _B, I _CSpectrum energy (E (A), E (B), E (C)) and the coefficient correlation (ρ between A, B, the C three-phase current frequency spectrum _AB, ρ _BC, ρ _AC).

Circuit one side A, B, C three-phase current spectrum energy and the current spectrum degree of correlation are definite by following formula (1) and (2) respectively,

$E\left(X\right)=\underset{n=0}{\overset{N}{\mathrm{\Σ}}}{x}^2\left(n\right)---\left(1\right)$

Wherein: E (X)---current spectrum energy, X are respectively A, B, C;

X (n)---current spectrum discrete sampling point, x is respectively A, B, C;

N---sampled point number.

${\mathrm{\ρ}}_{\mathrm{xy}}=\frac{\underset{n=0}{\overset{N}{\mathrm{\Σ}}}x\left(n\right)y\left(n\right)}{\max (E\left(X\right),E\left(Y\right))}\·\frac{\min (E\left(X\right),E\left(Y\right))}{\max (E\left(X\right),E\left(Y\right))}---\left(2\right)$

Wherein: ρ _Xy---the current spectrum degree of correlation, x, y are respectively A, B, C;

E (X)---current spectrum energy, X are respectively A, B, C;

E (Y)---current spectrum energy, Y are respectively A, B, C;

X (n)---current spectrum discrete sampling point, x is respectively A, B, C;

Y (n)---current spectrum discrete sampling point, y is respectively A, B, C;

N---sampled point number.

If I ₀Greater than zero-sequence current setting value ε ₁, ε ₁Be 0.1 times of rated current, compare ρ then _AB, ρ _BCAnd ρ _ACSize, if the three in ρ _ABMaximum, and E (A)＞E (C) are judged as AB double earthfault (ABg), otherwise E (A)＜E (C) is judged as C phase ground connection (Cg); If ρ among the three _BCMaximum, and E (B)＞E (A) are judged as BC double earthfault (BCg), otherwise E (B)＜E (A) is judged as A phase ground connection (Ag); If ρ among the three _ACMaximum, and E (A)＞E (B) are judged as AC double earthfault (ACg), otherwise E (A)＜E (B) is judged as B phase ground connection (Bg).

If I ₀Less than setting value ε ₁, and ρ _AB, ρ _BCAnd ρ _ACAll greater than setting value ε ₂, be judged as ABC three-phase shortcircuit (ABC); If ρ only _AB＞ε ₂(ε ₂Get 0.5), be judged as AB line to line fault (AB); If ρ only _BC＞ε ₂, be judged as BC line to line fault (BC); If ρ only _AC＞ε ₂, be judged as AC line to line fault (AC).

Fig. 2 is whether the present invention is based on relevant in the failure resonant frequency guard method is the protection criterion flow chart of troubles inside the sample space.As shown in Figure 2, described protection criterion flow process based on failure resonant frequency comprises:

Select in fault on the basis of phase, if A is the fault phase mutually, the current spectrum degree of correlation ρ of computational scheme both sides A phase _{AA '}, if ρ _{AA '}Greater than setting value ε ₃(ε ₃Get 0.5), be judged as external area error, if ρ _{AA '}Less than setting value ε ₃, be judged as troubles inside the sample space;

Frequency spectrum relatedness computation formula between the fault phase current of circuit both sides is determined by formula (3).

${\mathrm{\ρ}}_{{\mathrm{XX}}^{\′}}=\frac{\underset{n=0}{\overset{N}{\mathrm{\Σ}}}x\left(n\right)x^{\′}\left(n\right)}{\max (E\left(X\right),E\left(X^{\′}\right))}\·\frac{\min (E\left(X\right),E\left(X^{\′}\right))}{\max (E\left(X\right),E\left(X^{\′}\right))}---\left(3\right)$

Wherein: ρ _{XX '}---the frequency spectrum degree of correlation between the fault phase current of circuit both sides, X, X ' are respectively A, B, C;

X (n)---circuit 1 side fault phase current frequency spectrum discrete sampling point, x is respectively A, B, C;

X ' is (n)---the corresponding fault phase current of circuit opposite side frequency spectrum discrete sampling point, and x ' is respectively A, B, C;

E (X)---circuit one side fault phase current spectrum energy, X is respectively A, B, C;

E (X ')---the corresponding fault phase current of circuit opposite side spectrum energy, X ' is respectively A, B, C;

N---sampled point number.

If B is the fault phase mutually, the current spectrum degree of correlation ρ of computational scheme two ends B phase _{BB '}, if ρ _{BB '}Greater than setting value ε ₃, be judged as external area error, if ρ _{BB '}Less than setting value ε ₃, be judged as troubles inside the sample space;

If C is the fault phase mutually, the current spectrum degree of correlation ρ of computational scheme two ends C phase _{CC '}, if ρ _{CC '}Greater than setting value ε ₃, be judged as external area error, if ρ _{CC '}Less than setting value ε ₃, be judged as troubles inside the sample space.

This scheme is utilized failure resonant frequency to carry out the fault choosing and is protected criterion with constituting mutually; be not subjected to the influence of system oscillation and load current; verify through power system simulation software (PSCAD); this scheme desired data window is less than 10ms; very help quickly and reliably excising fault, help the stable of electric power system and safely, help improving the reliability of power supply.

For the purpose of illustration and description, provide the description of the front of the preferred embodiment of the present invention.It is not detailed or limits the invention to the accurate form of exposure.According to top instruction many modifications and variations is possible.Scope of the present invention is not to be limited by this detailed description, but defined by the appended claims.

Claims (7)

1. the guard method based on failure resonant frequency is characterized in that, described method comprises step:

(1) circuit one side A, B, C three-phase current and the zero-sequence current of collection protective device installation place, by difference algorithm filtering aperiodic component, the frequency spectrum degree of correlation between calculating A, B, the C three-phase current and the spectrum energy of three-phase current;

(2) when circuit is short-circuited fault, zero-sequence current of being gathered and the zero-sequence current setting value of presetting are compared, if described zero-sequence current is greater than described zero-sequence current setting value, then be judged as circuit generation earth fault, if zero-sequence current less than described zero-sequence current setting value, then is judged as circuit generation phase fault;

(3), judge the earth fault phase of described circuit or the phase fault phase of described circuit according to the frequency spectrum degree of correlation between described A, B, the C three-phase current and the spectrum energy of three-phase current:

When judging circuit generation earth fault, if in the three-phase current frequency spectrum degree of correlation of described calculating, A, B biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, B biphase current is judged as A, B double earthfault greater than the spectrum energy of C phase current;

If in the described three-phase current frequency spectrum degree of correlation, B, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of B, C biphase current is judged as B, C double earthfault greater than the spectrum energy of A phase current;

If in the described three-phase current frequency spectrum degree of correlation, A, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, C biphase current is judged as A, C double earthfault greater than the spectrum energy of B phase current;

If in the described three-phase current frequency spectrum degree of correlation, A, B biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, B biphase current is judged as C phase earth fault less than the spectrum energy of C phase current;

If in the described three-phase current frequency spectrum degree of correlation, B, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of B, C biphase current is judged as A phase earth fault less than the spectrum energy of A phase current;

If in the described three-phase current frequency spectrum degree of correlation, A, C biphase current frequency spectrum degree of correlation maximum, and the spectrum energy of A, C biphase current is judged as B phase earth fault less than the spectrum energy of B phase current;

When circuit generation phase fault, if A, B, the C three-phase current frequency spectrum degree of correlation during all greater than frequency spectrum degree of correlation setting value, are judged as circuit three phase short circuit fault has taken place;

If only A, the B biphase current frequency spectrum degree of correlation are judged as A, B two-phase short-circuit fault greater than described current spectrum degree of correlation setting value;

If only B, the C biphase current frequency spectrum degree of correlation are judged as B, C two-phase short-circuit fault greater than current spectrum degree of correlation setting value;

If only A, the C biphase current frequency spectrum degree of correlation are judged as A, C two-phase short-circuit fault greater than current spectrum degree of correlation setting value.

2. the guard method based on failure resonant frequency according to claim 1 is characterized in that, described zero-sequence current setting value is preferably 0.1 times of rated current.

3. the guard method based on failure resonant frequency according to claim 1 and 2 is characterized in that, described frequency spectrum degree of correlation setting value is preferably 0.5.

4. the guard method based on failure resonant frequency according to claim 1 and 2 is characterized in that, circuit one side A, B, C three-phase current spectrum energy and the current spectrum degree of correlation are definite by following formula (1) and (2) respectively,

Wherein: E (X)---current spectrum energy, X are respectively A, B, C, represent A, B, C three-phase;

X (n)---current spectrum discrete sampling point, x is respectively A, B, C, represents A, B, C three-phase;

N---sampled point number;

Wherein: ρ _Xy---the current spectrum degree of correlation, x, y are respectively A, B, C, represent A, B, C three-phase;

E (X)---current spectrum energy, X are respectively A, B, C, represent A, B, C three-phase;

E (Y)---current spectrum energy, Y are respectively A, B, C, represent A, B, C three-phase;

X (n)---current spectrum discrete sampling point, x is respectively A, B, C, represents A, B, C three-phase;

Y (n)---current spectrum discrete sampling point, y is respectively A, B, C, represents A, B, C three-phase;

N---sampled point number.

5. the guard method based on failure resonant frequency according to claim 1 and 2, it is characterized in that, select in fault on the basis of phase, by calculating the frequency spectrum degree of correlation between the fault phase current of described circuit both sides, judge that described fault is troubles inside the sample space or external area error, when the frequency spectrum degree of correlation between the fault phase current of described circuit both sides during, be judged as external area error greater than the second current spectrum degree of correlation setting value; When the frequency spectrum degree of correlation between the fault phase current of described circuit both sides during, be judged as troubles inside the sample space less than the second current spectrum degree of correlation setting value.

6. the guard method based on failure resonant frequency according to claim 5 is characterized in that, the frequency spectrum relatedness computation formula between the fault phase current of circuit both sides is definite by formula (3),

Wherein: ρ _{XX '}---the frequency spectrum degree of correlation between the fault phase current of circuit both sides, X, X ' are respectively A, B, C, represent A, B, C three-phase;

X (n)---circuit 1 side fault phase current frequency spectrum discrete sampling point, x is respectively A, B, C, represents A, B, C three-phase;

X ' is (n)---the corresponding fault phase current of circuit opposite side frequency spectrum discrete sampling point, and x ' is respectively A, B, C, represents A, B, C three-phase;

E (X)---circuit one side fault phase current spectrum energy, X is respectively A, B, C, represents A, B, C three-phase;

E (X ')---the corresponding fault phase current of circuit opposite side spectrum energy, X ' is respectively A, B, C, represents A, B, C three-phase;

N---sampled point number.

7. according to claim 5 or 6 described guard methods, it is characterized in that the value of the described second current spectrum degree of correlation setting value is preferably 0.5 based on failure resonant frequency.

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