CN103390885A - Method for enabling distance protection to enter power system oscillation interlocking logic - Google Patents

Abstract

The invention relates to a method for enabling distance protection to enter power system oscillation interlocking logic. The method includes the following steps: 1) judging whether inter-phase current variation components act; 2) removing distance protection interlocking on yes judgment and calculating each inter-phase impedance Z phi phi on no judgment; 3) comparing the phase impedances with a distance protection II section impedance setting value, enabling a distance protection II section to enter the power supply oscillation interlocking logic and comparing the inter-phase impedances with a distance protection I section impedance setting value when the inter-phase impedances are smaller than the II section impedance setting value, and enabling the distance protection I section to enter the power system oscillation interlocking logic when the inter-phase impedances are smaller than the I section impedance setting value. The method has the advantage of being easy to achieve.

Description

A kind of distance protection enters the method for Power system swing block logic

Technical field

The present invention relates to a kind of method that distance protection enters the Power system swing block logic.

Background technology

Transmission line distance protecting is subject to the power system oscillation impact and misoperation, so need to and occur in the system fault-free after static-stability destroys to carry out fast the out-of-step blocking logic.The method that the distance protection of using at present enters the Power system swing block logic is the current judgement method; namely under the system fault-free;, if each phase current of protected circuit all carries out the out-of-step blocking logic greater than distance protection in static-stability current setting situation, adopt the current judgement method easily to cause the situation of distance protection malfunction, tripping to occur.

Summary of the invention

The purpose of this invention is to provide a kind of method that distance protection enters the Power system swing block logic, in order to solve the existing low problem of current judgement method stability.

For achieving the above object, the solution of the present invention is: a kind of distance protection enters the method for Power system swing block logic, comprises the steps:

1) judge whether each three-phase current variable quantity element moves;

2) when described current change quantity element action, the open distance protection blocking, when described current change quantity element does not move, calculate each phase to phase impedance;

3) more described each phase to phase impedance and distance protection II section impedance setting value; when described each phase to phase impedance during less than described II section impedance setting value; distance protection II section enters the Power system swing block logic; then more described each phase to phase impedance and distance protection I section impedance setting value; during less than described I section impedance setting value, distance protection I section enters the Power system swing block logic when described each phase to phase impedance.

The method of discrimination whether described each three-phase current variable quantity element moves is: each three-phase current instantaneous value of sampling, if exist y sampled value to meet following formula in x sampled value continuously

|(i _k-i _k-2T)-(i _k-2T-i _k-4T)|>I _set

Assert described current change quantity element action, in following formula, i _kFor the current sampled value of differentiating, i _K-nTFor the sampled value before the cycle of the n with respect to current sampled value, I _setFor default startup definite value.

X=6 in the above-mentioned method of sampling, y=3.

Beneficial effect of the present invention is: provide a kind of new distance protection to enter the method for Power system swing block logic, the measurement impedance Z of distance protection during the identification power system oscillation _{φ φ}Whether fall between active region, if power system oscillation but the measurement impedance Z of distance protection _{φ φ}Do not fall into the corresponding actions interval, even do not enter latching logic in vibration situation yet; If the measurement impedance Z of distance protection _{φ φ}Fall into the corresponding actions interval, but at this moment because of not yet generation systems disturbance, current change quantity does not move, distance protection enters the system oscillation latching logic, can malfunction.No matter how outside operational mode changes; between the active region of distance protection according to the protected circuit impedance setting; with system operation mode, do not change; being adapted to existing electric power system grid structure becomes increasingly complex; the situation that system operation mode is changeable; than conventional current method practical and reliable more, stability is higher.

Description of drawings

Fig. 1 is flow chart of the present invention.

Embodiment

The present invention will be further described in detail below in conjunction with accompanying drawing.

Whether the tradition blocking method utilizes current judgement method identification electric power system to vibrate and determines whether the locking distance protection, namely relies on load current greater than the identification of vibrating of static-stability current ration.adjust to put into practice with research through scene and find, during power system oscillation on circuit the power of the size of passing through property load current and circuit both sides power supply of equal value relevant, namely closely related with system operation mode, also closely related with the network configuration of electric power system on the other hand, therefore at existing power system network complex structure, more and more be difficult to the static-stability current ration is adjusted in the changeable situation of operational mode, must find new distance protection fast and reliable and carry out the method for system oscillation latching logic, the present invention has introduced a kind of new distance protection and has entered the method for Power system swing block logic.

As shown in Figure 1, the present invention adopts following steps to carry out.

Step 1:

At first differentiate each three-phase current variable quantity element and whether move, if having certain three-phase current variable quantity to move distance protection enters and starts the 160ms open logic, if each three-phase current variable quantity element all not have move enter step 2.

Whether the three-phase current variable quantity moves is adopted instantaneous sampling value to differentiate, and, if compare the absolute value variable quantity greater than starting definite value before having 3 sampled values and two weeks in continuous 6 sampled values, thinks the action of current change quantity element, and concrete formula is as follows

|(i _k-i _k-2T)-(i _k-2T-i _k-4T)|>I _set

I in following formula _kFor the current sampled value of differentiating, i _K-nTFor the sampled value before the cycle of the n with respect to current sampled value, I _setFor default startup definite value.

Step 2:

Calculate each phase to phase impedance Z _{Φ Φ}, adopt all-round fourier filter algorithm to calculate each voltage between phases U _{Φ Φ}And electric current I _{Φ Φ}, each phase to phase impedance Z _{Φ Φ}Computing formula be:

Step 3:

With each phase to phase impedance Z _{φ φ}With distance protection II section impedance setting value Z _IIsetCompare, if Z _{φ φ}＜Z _IIset, distance protection II section impedance relay enters the Power system swing block logic.And continue relatively each phase to phase impedance Z _{φ φ}With distance protection I section impedance setting value Z _IsetIf, Z _{φ φ}＜Z _Iset, distance protection I section impedance relay also enters the Power system swing block logic.

, if apart from I, II section impedance relay, all entered the system oscillation latching logic, keep 3s, and return to the step 1 circulation and differentiate.

Claims (3)

1. a distance protection enters the method for Power system swing block logic, it is characterized in that, comprises the steps:

1) judge whether each three-phase current variable quantity element moves;

2) when described current change quantity element action, the open distance protection blocking, when described current change quantity element does not move, calculate each phase to phase impedance;

3) more described each phase to phase impedance and distance protection II section impedance setting value; when described each phase to phase impedance during less than described II section impedance setting value; distance protection II section enters the Power system swing block logic; then more described each phase to phase impedance and distance protection I section impedance setting value; during less than described I section impedance setting value, distance protection I section enters the Power system swing block logic when described each phase to phase impedance.

2. a kind of distance protection according to claim 1 enters the method for Power system swing block logic; it is characterized in that; the method of discrimination whether described each three-phase current variable quantity element moves is: each three-phase current instantaneous value of sampling, if exist y sampled value to meet following formula in x sampled value continuously

|(i _k-i _k-2T)-(i _k-2T-i _k-4T)|>I _set

Assert described current change quantity element action, in following formula, i _kFor the current sampled value of differentiating, i _K-nTFor the sampled value before the cycle of the n with respect to current sampled value, I _setFor default startup definite value.

3. a kind of distance protection according to claim 2 enters the method for Power system swing block logic, it is characterized in that described x=6, described y=3.

Images