CN107026430A - A kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate - Google Patents

Abstract

The present invention provides a phase selection method for double-circuit lines on the same pole based on single-ended sudden change. The phase selection steps when a line fails are as follows: (1) Using the electrical quantity of a single-circuit line, when U ₂ ≠ 0, calculate Voltage mutations ΔU _AB , ΔU _BC and ΔU _CA , according to the amplitude relationship of the voltage mutations at the protection installation, divide the six-phase zone fault of the double-circuit line fault; (2) Calculate the current mutations ΔI _AB , ΔI _BC and ΔI BC of the two-circuit lines ΔI _CA , according to the relationship between the phase and amplitude of each current mutation at the protection installation, divide the further fault of the six-phase area fault of the double circuit fault; (3) when U ₂ = 0, the sequence impedance ΔZ ₁ and Z ₂ distinguish the current circuit Faulty line protection element. The invention has strong versatility, making it applicable in various operation modes of double-circuit lines; has strong flexibility; accurate phase selection results are more conducive to impedance calculation, fault distance measurement, reclosing, etc.; high reliability.

Description

A phase selection method for double-loop lines on the same pole based on single-end mutation

technical field

The invention relates to a protection algorithm for a high-voltage line, in particular to a phase selection method for a double-circuit line on the same pole based on a single-end sudden change.

Background technique

Parallel double-circuit lines on the same pole have been widely used in 220kV and above voltage level systems. When a double-circuit line on the same pole fails, especially when a cross-line fault occurs, the correctness and reliability of relay protection will greatly affect the safe and stable operation of the power system and the reliability of power transmission.

At present, most of the phase selection methods for double-circuit lines on the same pole used in the field are derived from the improvement of the traditional phase selection method based on the electrical quantity of single-ended single-circuit lines that is suitable for single-circuit lines. This kind of phase selection method can correctly select the phase when a single circuit fault occurs, and can only select the fault phase of the current circuit when a cross-line fault occurs, but cannot make a judgment on the fault phase of the adjacent line. Theoretically, the six-sequence component phase selection can better identify various single-circuit faults and cross-line faults that occur in parallel double-circuit lines on the same pole, but it is easy to misselect the phase when there are positive and negative two-point faults.

If a cross-line fault occurs and a cross-line fault occurs, selecting an appropriate distance protection algorithm according to the fault type and phase is one of the indispensable conditions to ensure the correct operation of the distance protection. At the same time, most of the line faults are transient faults, and the correct phase selection of the phase selection components is required to provide a basis for investing in an appropriate reclosing strategy to ensure successful reclosing.

Contents of the invention

Aiming at the problems of phase selection refusal and misoperation in double circuit lines on the same pole mentioned in the background technology, the present invention proposes a sudden phase selection method suitable for double circuit lines on the same pole. In this method, the electric quantity of two circuits is used to calculate the voltage and current mutations to realize fault phase selection. First, calculate the voltage mutation amount based on the measured three-phase voltage, and use the amplitude relationship between the three mutation amounts as the basis for initial phase selection; then calculate the current mutation amount based on the measured three-phase currents of the two loop lines. The amplitude relationship between the current mutations further completes the phase selection and realizes the complete discrimination of the fault phase. The invention can make up for the disadvantages of incomplete phase selection function and even wrong phase selection of other phase selection methods currently used on double-circuit lines.

Technical problem of the present invention is mainly solved by following technical scheme:

A phase selection method for a double-circuit line on the same pole based on a single-ended sudden change, characterized in that the phase selection steps when the line fails are as follows:

(1) Using the electrical quantity of a single-circuit line, when U ₂ ≠ 0, calculate the voltage mutations ΔU _AB , ΔU _BC and ΔU _CA , and divide the six-phase area of the double-circuit line fault according to the amplitude relationship of the voltage mutation at the protection installation Fault;

(2) Calculate the current mutations ΔI _AB , ΔI _BC and ΔI _CA of the two-circuit lines, and divide the further faults of the six-phase zone faults of the double-circuit line faults according to the phase and amplitude relationship of each current mutation at the protection installation site;

(3) When U ₂ =0, the sequence impedance ΔZ ₁ and Z ₂ can judge the fault of the protection element of this circuit.

Further, the voltage mutations ΔU _AB , ΔU _BC and ΔU _CA are calculated, and according to the amplitude relationship of each voltage mutation at the protection installation, the division of 6 phase selection partitions similar to single circuit faults is done.

Further, for IIAIABC (phase A non-ground fault occurs on I loop line, ABC phase-to-phase unground fault occurs on II loop line), IAG (phase A ground fault occurs on I loop line), IIAIIAG (phase A ground fault occurs on I loop line Fault, phase A ground fault occurs in circuit II), IABIIAC and IACIIAB faults are distinguished, and the amplitude relationship among the current mutations of each circuit ΔI _IAB , ΔI _IBC , ΔI _ICA , ΔI _IIAB , ΔI _IIBC , ΔI _IICA is used to divide each type cross-line fault,

Among them: for the AB fault of the II loop, the fault current of C is superimposed on the approximate I loop;

For the A fault of the II loop, the fault current of BC is superimposed on the I loop approximation.

Further distinguish IAG and IAIIAG; use the amplitude relationship between the fault component currents of the two circuits to further divide the fault types,

Use the formula ΔI _I /ΔI _II >1.3 to determine whether an IAG fault has occurred; according to the formula ΔI _II /ΔI _I >1.3, determine whether an IIAG fault or IIAIIAG fault has occurred.

Further, using the amplitude relationship among the current mutation amounts ΔI _IAB , ΔI _IBC , ΔI _ICA , ΔI _IIAB , ΔI _IIBC , ΔI _IICA to distinguish the following types of cross-line faults:

IBIIC, IBIIBC, IBCIIC, IBCIIB, IBCIIABC, ICIIB, ICIIBC, IBC, IIBC, or IBCIIBC failure.

Further, use the amplitude relationship between the fault component currents of the two circuits to distinguish the fault IBC or IBCIIBC,

Use the formula ΔI _IBC /ΔI _IIBC >1.3 to determine whether an IBC failure has occurred, and use the formula ΔI _IIBC /ΔI _IBC >1.3 to determine whether an IIBC failure or an IBCIIBC failure has occurred.

Furthermore, when the fault IABC, IABCIIABC or IAIIBCG occurs (A phase-to-ground fault occurs in the I loop, and the BC phase indirect ground fault occurs in the II loop), and the negative sequence voltage U ₂ at the protection installation is 0, then according to the current Identify the type of failure.

Compared with the prior art, the present invention has the following beneficial effects:

1. The double-circuit line fault phase selection targeted by the present invention, with the rapid construction of intelligent substations, the two-circuit lines can easily realize the sharing of electric power. Under the premise that the double-circuit line is used as the protection unit, the judgment process is based on the single-end of the double-circuit line The electrical quantity has strong versatility, making it applicable to various operating modes of double-circuit lines.

2. The present invention can further perform fault phase selection in combination with the phase selection information of adjacent lines, and has strong flexibility.

3. The accurate phase selection result of the present invention is more conducive to impedance calculation, fault distance measurement, reclosing and so on.

4. The present invention can better realize the distance protection of this line and the correct operation of the reclosing switch, and the fault protection of adjacent lines is correctly blocked, and has high reliability.

Description of drawings

Figure 1 is a system diagram of cross-line faults on double-circuit lines.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

Example:

1. A phase selection method for double-circuit lines on the same pole based on single-ended mutation is proposed. When a fault occurs in the line, the following phase selection method is adopted:

(1) Using the electrical quantity of a single circuit, when U ₂ ≠ 0, calculate the voltage mutation ΔU _AB , ΔU _BC , ΔU _CA , and judge the relationship between the amplitude of the voltage mutation at the protection installation, and carry out the seven-circuit fault diagnosis of the double circuit Phase zone fault division;

(2) Further, calculate the current mutation amounts ΔI _AB , ΔI _BC , ΔI _CA of the two loops. By judging the relationship between the phase and amplitude of each current mutation at the protection installation, further fault division of double-circuit faults is carried out;

(3) When U ₂ =0, use the sequence impedance ΔZ ₁ , Z ₂ to complete the fault discrimination of the protection element of this circuit.

2. Calculate the voltage mutations ΔU _AB , ΔU _BC , ΔU _CA , and determine the relationship between the magnitudes of the voltage mutations at the protection installation site to perform a relationship similar to the six phase-selection partitions for single-line faults. (Typical values need to be given according to simulation)

3. For further distinguishing IAIIABC, IAG, IIAIIAG, IABIIAC, and IACIIAB faults, it is proposed to use the amplitude relationship between the current mutation amounts of each circuit ΔI _IAB , ΔI _IBC , ΔI _ICA , ΔI _IIAB , ΔI _IIBC , and ΔI _IICA to further complete each fault. Distinguish between class cross-line faults.

I circuit fault characteristics II circuit fault characteristics Fault type ΔI _IBC <<(ΔI _IAB ,ΔI _ICA ) ΔI _IIAB = ΔI _IIBC = ΔI _IICA IAIIABC ΔI _IBC <<(ΔI _IAB ,ΔI _ICA ) ΔI _IIBC <<(ΔI _IIAB ,ΔI _IICA ) IAG, IAIIAG, IIAG ΔI _ICA >(ΔI _IBC ,ΔI _IAB ) ΔI _IIAB >(ΔI _IIBC ,ΔI _IICA ) IACIIAB ΔI _IAB >(ΔI _IBC ,ΔI _ICA ) ΔI _IICA >(ΔI _IIBC ,ΔI _IIAB ) IABIIAC

Note: For the AB fault of the II loop, the fault current of C is superimposed on the I loop approximation.

The A fault of the II loop superimposes the BC fault current on the I loop approximation.

4. Further distinguish IAG and IIAIIAG; propose to use the amplitude relationship between the fault component currents of the two circuits to further complete the fault type distinction. If ΔI _I /ΔI _II >1.3 is satisfied between the fault component currents, an IAG fault occurs; if the fault component currents satisfy ΔI _II /ΔI _I >1.3, an IIAG fault occurs; otherwise, an IAG fault occurs.

5. For further distinguishing IBIIC, IBIIBC, IBCIIC, IBCIIB, IBCIIABC, ICIIB, ICIIBC, IBC, IIBC, and IBCIIBC faults, it is proposed to use the current mutation amount of each circuit ΔI _IAB , ΔI _IBC , ΔI _ICA , ΔI _IIAB , ΔI _IIBC , ΔI _IICA The amplitude relationship between them further completes the distinction of various cross-line faults.

I circuit fault characteristics II circuit fault characteristics Fault type ΔI _ICA <<(ΔI _IAB ,ΔI _IBC ) ΔI _IIAB <<(ΔI _IICA ,ΔI _IIBC ) IBIIC ΔI _ICA <<(ΔI _IAB ,ΔI _IBC ) ΔI _IIBC >(ΔI _IIAB ,ΔI _IICA ) IBIIBC ΔI _IBC >(ΔI _IAB ,ΔI _ICA ) ΔI _IIAB <<(ΔI _IICA ,ΔI _IIBC ) IBCIIC ΔI _IBC >(ΔI _IAB ,ΔI _ICA ) ΔI _IICA <<(ΔI _IIAB ,ΔI _IIBC ) IBCIIB ΔI _IBC >(ΔI _IAB ,ΔI _ICA ) ΔI _IIAB = ΔI _IIBC = ΔI _IICA IBCIIABC ΔI _IBC >(ΔI _IAB ,ΔI _ICA ) ΔI _IIBC >(ΔI _IIAB ,ΔI _IICA ) IBC, IBCIIBC, IIBC ΔI _IAB <<(ΔI _ICA ,ΔI _IBC ) ΔI _IICA <<(ΔI _IIAB ,ΔI _IIBC ) ICIIB ΔI _IAB <<(ΔI _ICA ,ΔI _IBC ) ΔI _IIBC >(ΔI _IIAB ,ΔI _IICA ) ICIIBC

6. Further distinguish IBC and IBCIIBC; propose to use the amplitude relationship between the fault component currents of the two circuits to further complete the fault type distinction. If the fault component currents satisfy ΔI _IBC /ΔI _IIBC >1.3, an IBC fault occurs; if the positive sequence fault component currents satisfy ΔI _IIBC /ΔI _IBC >1.3, an IIBC fault occurs; otherwise, an IBC IIBC occurs.

7. When a fault occurs (IABC, IABCIIABC, IAIIBCG), there is no negative sequence voltage at the protection installation, that is, U ₂ =0. Therefore, it is necessary to distinguish the fault type according to the current.

The above content is only an embodiment of the present invention, and its purpose is not to limit the system and method proposed by the present invention. The scope of protection of the present invention is subject to the claims. Without departing from the spirit and scope of the invention, various obvious modifications or changes in form and details made by those skilled in the art without departing from the scope and spirit of the invention shall fall within the scope of this invention. within the scope of protection of the invention.

Claims (7)

1. a kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate, it is characterised in that event occurs for circuit Phase selection step during barrier is as follows：

(1) using the electrical quantity of single loop line, U is worked as₂When ≠ 0, voltage jump amount Δ U is calculated_AB, Δ U_BCWith Δ U_CA, Six phase region failures of double line down are divided according to protection installation place voltage jump amount magnitude relation；

(2) the jump-value of current Δ I of two loop lines is calculated_AB, Δ I_BCWith Δ I_CA, according to the protection each electric current in installation place Sudden Changing Rate phase and magnitude relation divide the further failure of six phase region failures of double line down；

(3) U is worked as₂When=0, sequence impedance Δ Z₁And Z₂Differentiate the failure of this loop line protection element.

2. a kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate as claimed in claim 1, it is special Levy and be, calculate voltage jump amount Δ U_AB、ΔU_BCWith Δ U_CA, according to the protection each voltage jump amount width in installation place Value relation does the division of similar 6 phase selection subregions of single line down.

3. a kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate as claimed in claim 2, it is special Levy and be, for IAIIABC, IAG, IAIIAG, IABIIAC and IACIIAB fault distinguish, utilize Each loop line jump-value of current Δ I_IAB, Δ I_IBC, Δ I_ICA, Δ I_IIAB, Δ I_IIBC, Δ I_IICABetween magnitude relation draw Divide all kinds of cross line faults,

Wherein：The AB failures of II loop lines, are superimposed C fault current on I loop lines are approximate；

The A failures of II loop lines, are superimposed BC fault current on I loop lines are approximate.

4. a kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate as claimed in claim 3, it is special Levy and be, further discriminate between IAG, IAIIAG；Utilize the magnitude relation between two line down current weights Fault type is further divided,

With formula Δ I_I/ΔI_II>1.3 determine whether to there occurs IAG failures；According to formula Δ I_II/ΔI_I>1.3, it is determined that there occurs IIAG failures or IAIIAG failures.

5. a kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate as claimed in claim 2, it is special Levy and be, with each loop line jump-value of current Δ I_IAB, Δ I_IBC, Δ I_ICA, Δ I_IIAB, Δ I_IIBC, Δ I_IICABetween Magnitude relation, distinguishes following all kinds of cross line faults：

IBIIC、IBIIBC、IBCIIC、IBCIIB、IBCIIABC、ICIIB、ICIIBC、IBC、IIBC Or IBCIIBC failures.

6. a kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate as claimed in claim 4, it is special Levy and be, with the magnitude relation between two line down current weights, distinguish failure IBC or IBCIIBC,

With formula Δ I_IBC/ΔI_IIBC>1.3 determine whether to there occurs IBC failures, with formula Δ I_IIBC/ΔI_IBC>1.3 determine hair Give birth to IIBC failures or give birth to IBCIIBC failures.

7. a kind of double-circuit line on same pole phase-selecting method based on single-ended Sudden Changing Rate as claimed in claim 1, it is special Levy and be, when break down IABC, IABCIIABC or IAIIBCG when, protect installation place negative sequence voltage U₂=0, when, then according to current judgement fault type.