CN103779836A - Transformer winding fault relay protection method based on ring current mutation feature - Google Patents

Abstract

The invention discloses a transformer winding fault relay protection method based on a ring current mutation feature. According to the transformer winding fault relay protection method based on the ring current mutation feature, firstly, the three-phase winding voltage and the three-phase winding current of the two Y sides of a transformer are measured, the zero sequence voltage and the zero sequence current of the two Y sides of the transformer are respectively calculated, and the zero sequence current and the zero sequence voltage of the two Y sides of the transformer are converted to the delta sides of the transformer respectively according to the ratio of transformation. Winding parameters of the two Y sides of the transformer are converted to the delta sides of the transformer according to the ratio of transformation and ring current mutation coefficients of the delta sides of the transformer are calculated. Afterwards, the ring current mutation coefficients of the delta sides of the transformer and the setting threshold value form relay protection criteria. According to the transformer winding fault relay protection method, the feature that mutation of the ring currents of the delta sides of the transformer can occur when the transformer winding breaks down is used for accurately and reliably detecting the transformer winding fault. The acting performance is not affected by the transformer magnetizing current, the transition resistance and the overload current. The acting performance is accurate and reliable and reliability of the transformer relay protection action is effectively improved.

Description

Based on abrupt transition characteristic transformer winding fault relay protecting method

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to a kind of based on abrupt transition characteristic transformer winding fault relay protecting method.

Background technology

The 220kV transformer of electric power system extensive use adopts three-phase three-winding transformer conventionally.In order to guarantee that phase electromotive force is close to sine wave, for triple-frequency harmonics provides path, three-phase three-winding transformer must have one group of winding to adopt delta connection, and therefore its mode of connection is △/Y/Y wiring.

Current differential protection is the main protection of transformer, and difference between current momentum is zero when making normally to move, two groups of Y side electric currents of transformer need be converted to △ side or △ side electric current is converted to two groups of Y sides, to eliminate unsymmetrical current.In order to eliminate unsymmetrical current; mainly adopt at present the current compensation mode that two groups of Y side electric currents is converted to the current compensation mode of △ side and △ side electric current is converted to two groups of Y sides; but the difference between current momentum after this two kinds of mapping modes conversion all can not correct response transformer magnetizing current impact; cause as the current differential protection Reliability of Microprocessor of transformer main protection influenced; also make to utilize the method reliability of second harmonic differentiation magnetizing inrush current and short trouble not high, the safe and stable operation of electrical network in serious threat.

Summary of the invention

The invention provides one based on abrupt transition characteristic transformer winding fault relay protecting method, it has overcome the deficiencies in the prior art described in background technology.

The technical scheme adopting that the present invention solves its technical problem is:

Based on abrupt transition characteristic transformer winding fault relay protecting method, it comprises following sequential steps:

Step 1, the three-phase winding voltage u of two groups of Y sides of protective relaying device measuring transformer _a2, u _b2, u _c2and u _a3, u _b3, u _c3, the three-phase winding current i of two groups of Y sides of measuring transformer _a2, i _b2, i _c2and i _a3, i _b3, i _c3;

Step 2, the residual voltage of two groups of Y sides of protective relaying device calculating transformer

$u_{03}=\frac{u_{a3}+u_{b3}+u_{c3}}{3}$ And zero-sequence current $i_{02}=\frac{i_{a2}+i_{b2}+i_{c2}}{3},i_{03}=\frac{i_{a3}+i_{b3}+i_{c3}}{3};$

Step 3, the change coefficient k of protective relaying device calculating transformer △ side ring stream:

$k=\frac{u_{02}^{\′}-u_{03}^{\′}-i_{02}^{\′}{r}_2^{\′}+i_{03}^{\′}{r}_3^{\′}}{m_{12}^{\′}-m_{13}^{\′}}-\frac{L_2^{\′}-m_{23}^{\′}}{m_{12}^{\′}-m_{13}^{\′}}\frac{{\mathrm{di}}_{02}^{\′}}{\mathrm{dt}}+\frac{L_3^{\′}-m_{23}^{\′}}{m_{12}^{\′}-m_{13}^{\′}}\frac{{\mathrm{di}}_{03}^{\′}}{\mathrm{dt}}$

Wherein:

the residual voltage u of two groups of Y sides of indication transformer respectively ₀₂, u ₀₃convert the residual voltage of △ side by no-load voltage ratio;

the zero-sequence current i of two groups of Y sides of indication transformer respectively ₀₂, i ₀₃convert the zero-sequence current of △ side by no-load voltage ratio;

two groups of Y side windings of indication transformer are from leakage inductance L corresponding to leakage flux respectively ₂, L ₃leakage inductance by square conversion of no-load voltage ratio to △ side;

the resistance r of two groups of Y sides of indication transformer respectively ₂, r ₃resistance by square conversion of no-load voltage ratio to △ side; n ₁for transformer △ side umber of turn; n ₂, n ₃for two groups of Y side umber of turns of transformer;

represent i ' ₀₂derivative;

represent i ' ₀₃derivative;

the leakage inductance m corresponding to mutual leakage flux of two groups of Y sides of indication transformer ₂₃leakage inductance by square conversion of no-load voltage ratio to △ side;

the indication transformer △ side leakage inductance m corresponding with the mutual leakage flux of two groups of Y sides ₁₂, m ₁₃leakage inductance by square conversion of no-load voltage ratio to △ side;

Step 4; protective relaying device judges that the change coefficient k of transformer △ side ring stream is greater than the threshold value of adjusting and whether sets up; if set up; judge that Transformer Winding breaks down; protective relaying device sends action trip signal; tripping transformer three side circuit breakers, if be false, protective relaying device does not send action trip signal.

The technical program is compared with background technology, and its tool has the following advantages:

Transformer △ side ring this characteristic of undergoing mutation that fails to be convened for lack of a quorum when the inventive method is utilized transformer winding fault; by the change coefficient k of calculating transformer △ side ring stream; realize the correct reliable Detection of transformer winding fault; performance is not subject to the impact of transformer magnetizing current, transition resistance and load current; performance accurately and reliably, effectively improves transformer relay protecting Reliability of Microprocessor.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the invention will be further described.

Fig. 1 is △/Y/Y wiring transformer schematic diagram of application the inventive method.

Embodiment

Please refer to Fig. 1, in the present embodiment, protective relaying device is by the three-phase winding voltage u of two groups of Y sides of voltage measuring transformer transformer _a2, u _b2, u _c2and u _a3, u _b3, u _c3, by the three-phase winding current i of two groups of Y sides of current transformer measuring transformer _a2, i _b2, i _c2and i _a3, i _b3, i _c3;

And then, the residual voltage of two groups of Y sides of protective relaying device calculating transformer

$u_{03}=\frac{u_{a3}+u_{b3}+u_{c3}}{3}$ And zero-sequence current $i_{02}=\frac{i_{a2}+i_{b2}+i_{c2}}{3},i_{03}=\frac{i_{a3}+i_{b3}+i_{c3}}{3};$

And then, the change coefficient k of protective relaying device calculating transformer △ side ring stream:

$k=\frac{u_{02}^{\′}-u_{03}^{\′}-i_{02}^{\′}{r}_2^{\′}+i_{03}^{\′}{r}_3^{\′}}{m_{12}^{\′}-m_{13}^{\′}}-\frac{L_2^{\′}-m_{23}^{\′}}{m_{12}^{\′}-m_{13}^{\′}}\frac{{\mathrm{di}}_{02}^{\′}}{\mathrm{dt}}+\frac{L_3^{\′}-m_{23}^{\′}}{m_{12}^{\′}-m_{13}^{\′}}\frac{{\mathrm{di}}_{03}^{\′}}{\mathrm{dt}}$

Wherein:

the residual voltage u of two groups of Y sides of indication transformer respectively ₀₂, u ₀₃convert the residual voltage of △ side by no-load voltage ratio; the zero-sequence current i of two groups of Y sides of indication transformer respectively ₀₂, i ₀₃convert the zero-sequence current of △ side by no-load voltage ratio;

two groups of Y side windings of indication transformer are from leakage inductance L corresponding to leakage flux respectively ₂, L ₃leakage inductance by square conversion of no-load voltage ratio to △ side;

the resistance r of two groups of Y sides of indication transformer respectively ₂, r ₃resistance by square conversion of no-load voltage ratio to △ side; n ₁for transformer △ side umber of turn; n ₂, n ₃for two groups of Y side umber of turns of transformer;

represent i ' ₀₂derivative;

represent i ' ₀₃derivative;

the leakage inductance m corresponding to mutual leakage flux of two groups of Y sides of indication transformer ₂₃leakage inductance by square conversion of no-load voltage ratio to △ side; the indication transformer △ side leakage inductance m corresponding with the mutual leakage flux of two groups of Y sides respectively ₁₂, m ₁₃leakage inductance by square conversion of no-load voltage ratio to △ side;

Finally; protective relaying device judges that the change coefficient k of transformer △ side ring stream is greater than the threshold value of adjusting and whether sets up; if set up; judge that Transformer Winding breaks down; protective relaying device sends action trip signal; tripping transformer three side circuit breakers, if be false, protective relaying device does not send action trip signal.

Transformer △ side ring this characteristic of undergoing mutation that fails to be convened for lack of a quorum when the inventive method is utilized transformer winding fault; by the change coefficient k of calculating transformer △ side ring stream; realize the correct reliable Detection of transformer winding fault; performance is not subject to the impact of transformer magnetizing current, transition resistance and load current; performance accurately and reliably, effectively improves transformer relay protecting Reliability of Microprocessor.

The above, only for preferred embodiment of the present invention, therefore can not limit according to this scope of the invention process, the equivalence of doing according to the scope of the claims of the present invention and description changes and modifies, and all should still belong in the scope that the present invention contains.

Claims (1)

1. based on abrupt transition characteristic transformer winding fault relay protecting method, it is characterized in that, comprise following sequential steps:

Step 1, the three-phase winding voltage u of two groups of Y sides of relay protective relaying device measuring transformer _a2, u _b2, u _c2and u _a3, u _b3, u _c3, the three-phase winding current i of two groups of Y sides of measuring transformer _a2, i _b2, i _c2and i _a3, i _b3, i _c3;

Step 2, the residual voltage of two groups of Y sides of protective relaying device calculating transformer

$u_{03}=\frac{u_{a3}+u_{b3}+u_{c3}}{3}$ And zero-sequence current $i_{02}=\frac{i_{a2}+i_{b2}+i_{c2}}{3},i_{03}=\frac{i_{a3}+i_{b3}+i_{c3}}{3};$

Step 3, the change coefficient k of protective relaying device calculating transformer △ side ring stream:

$k=\frac{u_{02}^{\′}-u_{03}^{\′}-i_{02}^{\′}{r}_2^{\′}+i_{03}^{\′}{r}_3^{\′}}{m_{12}^{\′}-m_{13}^{\′}}-\frac{L_2^{\′}-m_{23}^{\′}}{m_{12}^{\′}-m_{13}^{\′}}\frac{{\mathrm{di}}_{02}^{\′}}{\mathrm{dt}}+\frac{L_3^{\′}-m_{23}^{\′}}{m_{12}^{\′}-m_{13}^{\′}}\frac{{\mathrm{di}}_{03}^{\′}}{\mathrm{dt}}$

Wherein:

the residual voltage u of two groups of Y sides of indication transformer respectively ₀₂, u ₀₃convert the residual voltage of △ side by no-load voltage ratio;

the zero-sequence current i of two groups of Y sides of indication transformer respectively ₀₂, i ₀₃convert the zero-sequence current of △ side by no-load voltage ratio;

two groups of Y side windings of indication transformer are from leakage inductance L corresponding to leakage flux respectively ₂, L ₃leakage inductance by square conversion of no-load voltage ratio to △ side;

the resistance r of two groups of Y sides of indication transformer respectively ₂, r ₃resistance by square conversion of no-load voltage ratio to △ side; n ₁for transformer △ side umber of turn; n ₂, n ₃for two groups of Y side umber of turns of transformer;

represent i ' ₀₂derivative;

represent i ' ₀₃derivative;

the leakage inductance m corresponding to mutual leakage flux of two groups of Y sides of indication transformer ₂₃leakage inductance by square conversion of no-load voltage ratio to △ side;

the indication transformer △ side leakage inductance m corresponding with the mutual leakage flux of two groups of Y sides ₁₂, m ₁₃leakage inductance by square conversion of no-load voltage ratio to △ side;

Step 4; protective relaying device judges that the change coefficient k of transformer △ side ring stream is greater than the threshold value of adjusting and whether sets up; if set up; judge that Transformer Winding breaks down; protective relaying device sends action trip signal; tripping transformer three side circuit breakers, if be false, protective relaying device does not send action trip signal.