CN103746338A - Any phase-shifting angle special transformer differential protection method - Google Patents

Abstract

An any phase-shifting angle special transformer differential protection method comprises the following steps: 1) calculating any phase-shifting angle transformer differential protection fixed values; 2) collecting current data at the two sides of a transformer in real time, utilizing an any phase-shifting angle phase-shifting matrix to reduce currents, reducing the currents at the two sides of the transformer to the same phase, and then reducing the current data at the two sides of the transformer to the same voltage level; and 3) a control system of a transformer differential protection device taking the reduced current data to a transformer differential protection judgment scheme, calculating action amount and braking amount of transformer protection, and judging whether the transformer has internal faults by judging the amount relation of the action amount and braking amount; if the transformer has internal faults, the transformer differential protection device trips out; and if the transformer does not have internal faults, the control system of the transformer differential protection device goes back to the step 2) to recalculate. The protection method has the advantages of being suitable for the special transformer with a special wiring mode, convenient to wire, and easy to set.

Description

Phase shifting angle special transformer differential protecting method arbitrarily

Technical field

The present invention relates to the implementation method of electric system protection device, be specifically related to any phase shifting angle special transformer differential protecting method.

Background technology

Power transformer is the hinge equipment in electric power system, plays a part energy and voltage transitions in whole electric power system.Therefore can transformer safe and stable operation directly have influence on the safety and stablization of whole electric power system.Protective relaying device as electric power system " the first line of defence " will play vital effect therein.Differential protection is the main protection of power transformer always, and it has the advantages that based on Kirchhoff's current law (KCL) principle is simple, highly sensitive, selectivity is good.But rectifier transformer, due to the particularity of structure and the mode of connection, does not configure the main protection of differential protection as transformer.Increase electric parameters protection and will produce very large raising effect to transformer reliability service as the main protection of rectifier transformer.

In order to guarantee waveform smooth of DC bus, reduce the impact of harmonic wave on electrical network, often need to increase the pulse number of electric current and voltage, in order to increase pulse number, in rectifier transformer, used the phase shifting transformer of special wiring mode.Many phase shifting transformers in parallel in rectifier transformer; the phase shifting angle of every phase shifting transformer is different; special and different phase shifting angle brings very large difficulty to adjusting of relay protection device; the present invention just, on this basis by any phase shifting angle phase shift matrix of deriving, has designed any phase shifting angle special transformer differential relaying algorithm.

For conventional transformer differential protection, because Transformer Winding wiring group difference causes the larger unsymmetrical current of generation in differential circuit, require both sides TA secondary side to adopt the wiring of current phase penalty method for this reason.In transformer microcomputer protection, due to the flexibility that software calculates, allow transformer each side TA all press the wiring of Y type for bis-times, wait before calculating the data processing of carrying out current phase compensation starting to differ from stream.For different corner modes, in transformer differential loop, differential current is different, thereby the effect of magnetizing inrush current is differentiated in impact.

For rectifier transformer, for multiple transformers match, it has set special phase shifting angle, due to the special wiring form of rectifier transformer winding, the fixing corner mode of setting in traditional transformer can not adapt to, as the mode of still taking original fixing phase shifting angle is calculated, the unsymmetrical current of differential protection will further increase, if continue, adopt the setting mode that the escapes maximum imbalance current transformer differential protection definite value of adjusting, the sensitivity of rectifier transformer differential protection will further reduce, and because the unsymmetrical current that phase angle difference is brought cannot be eliminated, so very possible because the current fluctuation that external area error brings causes the misoperation of protection.Due to the decline of differential protection sensitivity, for the recognition capability of inner weak fault, will decline to some extent, and because the phase shifting angle of each rectifier transformer is all different, adjusting of set-point be brought to very large difficulty simultaneously.

For the problems referred to above, the special transformer differential relaying algorithm of any phase shifting angle of having derived herein, the differential relaying algorithm of applicable any phase shifting angle of derivation.

Summary of the invention

The problem existing in order to overcome above-mentioned prior art, the present invention proposes any phase shifting angle special transformer differential protecting method, have go for the special transformer of special wiring mode and have easy-to-connect, the simple feature of adjusting.

For achieving the above object, the present invention adopts following technical scheme to be achieved:

Phase shifting angle special transformer differential protecting method arbitrarily, comprises the following steps:

Step 1: calculate any phase shifting angle transformer differential protection definite value;

Step 2: by transducer Real-time Collection transformer both sides current data corresponding to differential protective device of transformer, and the protection definite value obtaining that step 1 is calculated is input in the control system of differential protective device of transformer, the any phase shifting angle phase shift of the control system utilization matrix reduction electric current of differential protective device of transformer, by the electric current reduction of transformer both sides under same phase, and then by the current data reduction of transformer both sides under identical electric pressure;

Described any phase shifting angle phase shift matrix M (θ) is as follows:

Wherein: the phase angle difference of q indication transformer both sides electric current;

By three-phase current I ₁, I ₂, I ₃, calculate zero-sequence current I ₀, computing formula I ₀=(I ₁+ I ₂+ I ₃)/3 obtain, and any phase shifting angle phase shift matrix M 0 (θ) of removing zero-sequence component is:

Step 3: the control system of differential protective device of transformer is brought into the current data of step 2 reduction in transformer differential protection differentiation scheme; actuating quantity and the braking amount of calculating transformer protection; and by judging the magnitude relationship of braking amount and actuating quantity; determine whether transformer internal fault occurs; if generation internal fault; differential protective device of transformer tripping operation, if there is not internal fault, the control system of differential protective device of transformer is returned to step 2 and is recalculated.

Described in step 1, the computational methods of phase shifting angle transformer differential protection definite value are arbitrarily: adopt DL/T684-1999 < < high-rating generator transformer relay protecting to adjust and calculate the transformer differential protection synchronizing calculation method stipulating in guide rule > >, while basis arbitrarily phase shifting angle special transformer physical cabling phase shifting angle is set phase shifting angle parameter.

The derivation method of any phase shifting angle phase shift matrix M (q) described in step 2 is as follows:

Utilize Principle of Symmetrical Component Method, the relation between three-phase phasor and symmetrical component be written as:

$\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]=A\&CenterDot;\left[\begin{array}{c}{I}_P\\ I_N\\ I_Z\end{array}\right]=\left[\begin{array}{ccc}1& 1& 1\\ a^2& a& 1\\ a& a^2& 1\end{array}\right]\&CenterDot;\left[\begin{array}{c}{I}_P\\ I_N\\ I_Z\end{array}\right]$

Wherein, I ₁, I ₂, I ₃be respectively transformer a, b, c three-phase current, I _p, I _n, I _zbe respectively transformer forward-order current, negative-sequence current and zero-sequence current, a is label symbol, a=e ^{j120 °}, A is phase-sequence current transformation matrix;

For phase shifting transformer, the current component of its both sides is decomposed according to symmetrical component method, the feature of component is known in order, the phase shifting transformer that is q for phase shifting angle, the leading secondary side forward-order current of its both sides electric current orderly component primary side forward-order current q, primary side negative-sequence current lags behind secondary side negative-sequence current q, both sides zero-sequence current phase place is identical, therefore first the current data collecting is transformed to order current component, through phase shifting angle phase shift, be transformed to again phase component, thereby realize any phase shifting angle phase shift;

$\left[\begin{array}{c}{I^{\&prime;}}_1\\ {I^{\&prime;}}_2\\ {I^{\&prime;}}_3\end{array}\right]=A\&CenterDot;\left[\begin{array}{ccc}{e}^{\mathrm{j\&theta;}}& 0& 0\\ 0& e^{-\mathrm{j\&theta;}}& 0\\ 0& 0& 1\end{array}\right]\&CenterDot;A^{\text{-1}}\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]$

Wherein: I ' ₁, I ' ₂, I ' ₃be respectively transformer a, b, c three-phase current after reduction.

Definition,

$M\left(\mathrm{\&theta;}\right)=A\&CenterDot;\left[\begin{array}{ccc}{e}^{\mathrm{j\&theta;}}& 0& 0\\ 0& e^{-\mathrm{j\&theta;}}& 0\\ 0& 0& 1\end{array}\right]\&CenterDot;A^{-1}$

Can be calculated

Thus, differential protection operation equation is write as:

Wherein: Id ₁, Id ₂, Id ₃for three-phase differential protection operating current, I _1W1, I _2W1, I _3W1for the three-phase current of winding W1 side, I _1W2, I _2W2, I _3W2for the three-phase current of winding W2 side.

Due to the mode of connection of phase shifting transformer, sometimes will cause zero-sequence current between primary side and secondary side, not transmit, need to carry out special processing for zero-sequence current, consider the effect of zero-sequence current, differential protection operation equation is write as:

Wherein, I0 _w1represent the zero-sequence current of winding W1 side, I0 _w2represent the zero-sequence current of winding W2 side, K _w1and K _w2for protection inner parameter, set point is 1 or 0, in order to determine whether removing zero-sequence current impact;

Zero-sequence current has following two kinds of acquisition methods:

1) from neutral point, directly measure zero-sequence current component;

2) by three-phase current, calculate

$I0=\frac{I_1+I_2+I_3}{3}$

When adopting internal current to calculate zero-sequence current, bring above formula into differential protection operation equation, calculate the phase shift matrix M 0 (θ) of new consideration zero sequence current affects:

Therefore,, after having considered zero-sequence current impact, differential protection operation equation is write as:

Wherein, in order to explain unification, W1 side does not have phase shift, and phase shifting angle is 0 °, with M0 (0 °) expression;

Phase shifting angle differential protection discrimination formula is write as the most arbitrarily:

$\left[\begin{array}{c}{\mathrm{Id}}_1\\ {\mathrm{Id}}_2\\ {\mathrm{Id}}_3\end{array}\right]=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\mathrm{MX}\left({\mathrm{\&theta;}}_{\mathrm{Wi}}\right)\&CenterDot;\left[\begin{array}{c}{I}_{1\mathrm{Wi}}\\ I_{2\mathrm{Wi}}\\ I_{3\mathrm{Wi}}\end{array}\right]$

Wherein, θ _wirepresent the angle of the required phase shift of corresponding each side, MX represents the phase shift matrix-type of choosing, and whether needs filtering zero-sequence current component.

Described in step 3, transformer differential protection differentiation scheme is ratio brake protection scheme or perunit value braking protection scheme.

The present invention compared to the prior art, possesses following advantage:

The present invention is by original, and the differential protecting method that is applicable to several link modes of transformer upgrades to the special wiring mode that goes for, arbitrarily the special transformer differential protecting method of phase shifting angle.Any phase shifting angle phase shift matrix of any phase shifting angle phase shift matrix and the removal zero-sequence component of having derived; do not changing original transformer differential protection wiring; do not increase in the situation of original transformer differential protection instrument transformer quantity; realized special transformer differential protecting method; from principle, be to have realized any phase shifting angle special transformer differential protecting method, from algorithm, effectively avoided the misoperation of differential protection and the problem that sensitivity declines.

Accompanying drawing explanation

Accompanying drawing is guard method flow chart of the present invention.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment, the present invention is described in further detail.

As shown in Figure 1, phase shifting angle special transformer differential protecting method arbitrarily, comprises the following steps:

Step 1: calculate any phase shifting angle transformer differential protection definite value;

Step 2: by transducer Real-time Collection transformer both sides current data corresponding to differential protective device of transformer, and the protection definite value obtaining that step 1 is calculated is input in the control system of differential protective device of transformer, the any phase shifting angle phase shift of the control system utilization matrix reduction electric current of differential protective device of transformer, by the electric current reduction of transformer both sides under same phase, and then by the current data reduction of transformer both sides under identical electric pressure;

Described any phase shifting angle phase shift matrix M (θ) is as follows:

Wherein: the phase angle difference of q indication transformer both sides electric current;

By three-phase current I ₁, I ₂, I ₃, calculate zero-sequence current I ₀, computing formula I ₀=(I ₁+ I ₂+ I ₃)/3 obtain, and any phase shifting angle phase shift matrix M 0 (θ) of removing zero-sequence component is:

Step 3: the control system of differential protective device of transformer is brought into the current data of step 2 reduction in transformer differential protection differentiation scheme; actuating quantity and the braking amount of calculating transformer protection; and by judging the magnitude relationship of braking amount and actuating quantity; determine whether transformer internal fault occurs; if generation internal fault; differential protective device of transformer tripping operation, if there is not internal fault, the control system of differential protective device of transformer is returned to step 2 and is recalculated.

Claims (4)

1. any phase shifting angle special transformer differential protecting method, is characterized in that, comprises the following steps:

Step 1: calculate any phase shifting angle transformer differential protection definite value;

Step 2: by transducer Real-time Collection transformer both sides current data corresponding to differential protective device of transformer, and the protection definite value that step 1 is calculated is input in the control system of differential protective device of transformer, the any phase shifting angle phase shift of the control system utilization matrix reduction electric current of differential protective device of transformer, by the electric current reduction of transformer both sides under same phase, and then by the current data reduction of transformer both sides under identical electric pressure;

Described any phase shifting angle phase shift matrix M (θ) is as follows:

Wherein: the phase angle difference of q indication transformer both sides electric current;

By three-phase current I ₁, I ₂, I ₃, calculate zero-sequence current I ₀, computing formula I ₀=(I ₁+ I ₂+ I ₃)/3 obtain, and any phase shifting angle phase shift matrix M 0 (θ) of removing zero-sequence component is:

Step 3: the control system of differential protective device of transformer is brought into the current data of step 2 reduction in transformer differential protection differentiation scheme; actuating quantity and the braking amount of calculating transformer protection; and by judging the magnitude relationship of braking amount and actuating quantity; determine whether transformer internal fault occurs; if generation internal fault; differential protective device of transformer tripping operation, if there is not internal fault, the control system of differential protective device of transformer is returned to step 2 and is recalculated.

2. any phase shifting angle special transformer differential protecting method according to claim 1; it is characterized in that: described in step 1, the computational methods of phase shifting angle transformer differential protection definite value are arbitrarily: adopt DL/T684-1999 < < high-rating generator transformer relay protecting to adjust and calculate the transformer differential protection synchronizing calculation method stipulating in guide rule > >, while basis arbitrarily phase shifting angle special transformer physical cabling phase shifting angle is set phase shifting angle parameter.

3. any phase shifting angle special transformer differential protecting method according to claim 1, is characterized in that: the derivation method of any phase shifting angle phase shift matrix M (q) described in step 2 is as follows:

Utilize Principle of Symmetrical Component Method, the relation between three-phase phasor and symmetrical component be written as:

$\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]=A\&CenterDot;\left[\begin{array}{c}{I}_P\\ I_N\\ I_Z\end{array}\right]=\left[\begin{array}{ccc}1& 1& 1\\ a^2& a& 1\\ a& a^2& 1\end{array}\right]\&CenterDot;\left[\begin{array}{c}{I}_P\\ I_N\\ I_Z\end{array}\right]$

Wherein, I ₁, I ₂, I ₃be respectively transformer a, b, c three-phase current, I _p, I _n, I _zbe respectively transformer forward-order current, negative-sequence current and zero-sequence current, a is label symbol, a=e ^{j120 °}, A is phase-sequence current transformation matrix;

For phase shifting transformer, the current component of its both sides is decomposed according to symmetrical component method, the feature of component is known in order, the phase shifting transformer that is q for phase shifting angle, the leading secondary side forward-order current of its both sides electric current orderly component primary side forward-order current q, primary side negative-sequence current lags behind secondary side negative-sequence current q, both sides zero-sequence current phase place is identical, therefore first the current data collecting is transformed to order current component, through phase shifting angle phase shift, be transformed to again phase component, thereby realize any phase shifting angle phase shift;

$\left[\begin{array}{c}{I^{\&prime;}}_1\\ {I^{\&prime;}}_2\\ {I^{\&prime;}}_3\end{array}\right]=A\&CenterDot;\left[\begin{array}{ccc}{e}^{\mathrm{j\&theta;}}& 0& 0\\ 0& e^{-\mathrm{j\&theta;}}& 0\\ 0& 0& 1\end{array}\right]\&CenterDot;A^{\text{-1}}\left[\begin{array}{c}{I}_1\\ I_2\\ I_3\end{array}\right]$

Wherein: I ' ₁, I ' ₂, I ' ₃be respectively transformer a, b, c three-phase current after reduction.

Definition,

$M\left(\mathrm{\&theta;}\right)=A\&CenterDot;\left[\begin{array}{ccc}{e}^{\mathrm{j\&theta;}}& 0& 0\\ 0& e^{-\mathrm{j\&theta;}}& 0\\ 0& 0& 1\end{array}\right]\&CenterDot;A^{-1}$

Can be calculated

Thus, differential protection operation equation is write as:

Wherein: Id ₁, Id ₂, Id ₃for three-phase differential protection operating current, I _1W1, I _2W1, I _3W1for the three-phase current of winding W1 side, I _1W2, I _2W2, I _3W2for the three-phase current of winding W2 side.

Due to the mode of connection of phase shifting transformer, sometimes will cause zero-sequence current between primary side and secondary side, not transmit, need to carry out special processing for zero-sequence current, consider the effect of zero-sequence current, differential protection operation equation is write as:

Wherein, I0 _w1represent the zero-sequence current of winding W1 side, I0 _w2represent the zero-sequence current of winding W2 side, K _w1and K _w2for protection inner parameter, set point is 1 or 0, in order to determine whether removing zero-sequence current impact;

Zero-sequence current has following two kinds of acquisition methods:

1) from neutral point, directly measure zero-sequence current component;

2) by three-phase current, calculate

$I0=\frac{I_1+I_2+I_3}{3}$

When adopting internal current to calculate zero-sequence current, bring above formula into differential protection operation equation, calculate the phase shift matrix M 0 (θ) of new consideration zero sequence current affects:

Therefore,, after having considered zero-sequence current impact, differential protection operation equation is write as:

Wherein, in order to explain unification, W1 side does not have phase shift, and phase shifting angle is 0 °, with M0 (0 °) expression;

Phase shifting angle differential protection discrimination formula is write as the most arbitrarily:

$\left[\begin{array}{c}{\mathrm{Id}}_1\\ {\mathrm{Id}}_2\\ {\mathrm{Id}}_3\end{array}\right]=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\mathrm{MX}\left({\mathrm{\&theta;}}_{\mathrm{Wi}}\right)\&CenterDot;\left[\begin{array}{c}{I}_{1\mathrm{Wi}}\\ I_{2\mathrm{Wi}}\\ I_{3\mathrm{Wi}}\end{array}\right]$

Wherein, θ _wirepresent the angle of the required phase shift of corresponding each side, MX represents the phase shift matrix-type of choosing, and whether needs filtering zero-sequence current component.

4. any phase shifting angle special transformer differential protecting method according to claim 1, is characterized in that: described in step 3, transformer differential protection differentiation scheme is ratio brake protection scheme or perunit value braking protection scheme.

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