CN104330703A - Inter-phase fault branch phase determination method for T-connection lines - Google Patents

Abstract

The invention discloses an inter-phase fault branch phase determination method for T-connection lines. The method comprises measuring the fault inter-phase voltage, the fault inter-phase and the fault inter-phase negative-sequence current at the protection mounting position of three branches of the T-connection line respectively, calculating the fault inter-phase voltage of the T-connection joint of three branches through a distributed parameter model respectively, determining whether the phase of the fault inter-phase voltage at the T-connection joint leads the phase of the fault inter-phase negative-sequence current at the protection mounting position of the three branches and the phase difference is less than zero, and the branch is the inter-phase fault branch of the T-connection line if the phase of the fault inter-phase voltage at the T-connection joint leads the phase of the fault inter-phase negative-sequence current at the protection mounting position of the three branches and the phase difference is less than zero. The method is applicable to fault branch judgment of the whole fault process after inter-phase short-circuit faults of T-connection lines, judgment results are not affected by transition resistances, load currents and fault positions. According to the method, during the inter-phase high-resistance short-circuit fault of T-connection lines, inter-phase fault branches of the T-connection lines can be judged accurately.

Description

T link phase-to phase fault branch road phase judgment method

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to a kind of T link phase-to phase fault branch road phase judgment method.

Background technology

When land resource day is becoming tight, T link due to floor area little, cost is low, has become a kind of common multi-line power transmission mode of electric system.The electric parameters such as voltage transformer (VT), current transformer collecting device is not installed at the T binding place place of T link, after causing T link to break down, need first failure judgement point on any bar branch road of T link, and then utilize two ends of electric transmission line fault distance-finding method to carry out fault localization to abort situation.Therefore, to the correctness of fault branch selection result, direct relation the whether accurate of T link localization of fault.

The system of selection of tradition T link fault branch utilizes the magnitude relationship Judging fault branch road of three branch roads between the voltage jump amount amplitude of T link T node.When trouble spot is near T link T node, by high transition Resistance Influence, article three, branch road is very little in the voltage jump amount amplitude difference of T link T node, add the impact by voltage transformer (VT), current transformer progress of disease error and harmonic component, there will be fault branch and be less than the voltage jump amount amplitude of normal branch road at T link T node in the voltage jump amount amplitude of T link T node, cause traditional T link fault branch system of selection failure judgement branch road mistake, cause the failure of T link fault localization.

Summary of the invention

The object of the invention is to the deficiency overcoming prior art existence, provide a kind of not by the T link phase-to phase fault branch road phase judgment method that transition resistance, load current and abort situation affect.

For achieving the above object, the inventive method adopts following technical scheme:

T link phase-to phase fault branch road phase judgment method, is characterized in that, comprise following sequential steps:

(1) protector measuring T link is at the fault voltage between phases of m end protection installation place fault three-phase current negative-sequence current between fault phase measure the fault voltage between phases of T link in n end protection installation place fault three-phase current negative-sequence current between fault phase measure the fault voltage between phases of T link in p end protection installation place fault three-phase current negative-sequence current between fault phase wherein, φ φ=AB, BC, CA phase;

(2) protective device judges on mt branch road leading angle be less than zero and whether set up, if set up, then protective device judges that mt branch road is the phase-to phase fault branch road of T link; Wherein, φ φ=AB, BC, CA phase; Three branch roads of T link are respectively mt branch road, nt branch road and pt branch road; T is the T binding place of three branch road mt branch roads, nt branch road and pt branch roads; Z _c1for electric transmission line positive sequence wave impedance; γ ₁for electric transmission line positive sequence propagation constant; l _mtfor the length of T link mt branch road; Cosh () is hyperbolic cosine function; Sinh () is hyperbolic sine function;

(3) protective device judges on nt branch road leading angle be less than zero and whether set up, if set up, then protective device judges that nt branch road is the phase-to phase fault branch road of T link; Wherein, φ φ=AB, BC, CA phase; l _ntfor the length of T link nt branch road; Cosh () is hyperbolic cosine function; Sinh () is hyperbolic sine function;

(4) protective device judges on pt branch road leading angle be less than zero and whether set up, if set up, then protective device judges that pt branch road is the phase-to phase fault branch road of T link; Wherein, φ φ=AB, BC, CA phase; l _ptfor the length of T link pt branch road; Cosh () is hyperbolic cosine function; Sinh () is hyperbolic sine function.

Feature of the present invention and technological achievement:

The inventive method utilizes distributed parameter model to calculate the fault voltage between phases of three branch roads at T binding place respectively; judge that three branch roads phase place of negative-sequence current between the fault phase of the fault voltage between phases of T binding place its protection installation place leading is less than zero and whether sets up respectively; if there is branch road phase place of negative-sequence current between the fault phase of the fault voltage between phases of T binding place its protection installation place leading to be less than zero establishment, then judge that this branch road is the phase-to phase fault branch road of T link.After the inventive method is applicable to T link phase fault, the fault branch of whole failure process differentiates, differentiates result not by the impact of transition resistance, load current and abort situation.During the alternate high resistant short trouble of T link, the inventive method accurately can judge the phase-to phase fault branch road of T link.

Accompanying drawing explanation

Fig. 1 is the T link transmission system schematic diagram of application the inventive method.

Embodiment

According to Figure of description, technical scheme of the present invention is expressed in further detail below.

Fig. 1 is the T link transmission system schematic diagram of application the inventive method.In Fig. 1, CT is current transformer, CVT is voltage transformer (VT).In the present embodiment, three branch roads of T link are respectively mt branch road, nt branch road and pt branch road, and t is the T binding place of three branch road mt branch roads, nt branch road and pt branch roads.

Protector measuring T link is at the fault voltage between phases of m end protection installation place fault three-phase current negative-sequence current between fault phase measure the fault voltage between phases of T link in n end protection installation place fault three-phase current negative-sequence current between fault phase measure the fault voltage between phases of T link in p end protection installation place fault three-phase current negative-sequence current between fault phase wherein, φ φ=AB, BC, CA phase.

Protective device judges on mt branch road leading angle be less than zero and whether set up, if set up, then protective device judges that mt branch road is the phase-to phase fault branch road of T link.

Protective device judges on nt branch road leading angle be less than zero and whether set up, if set up, then protective device judges that nt branch road is the phase-to phase fault branch road of T link.

Protective device judges on pt branch road leading angle be less than zero and whether set up, if set up, then protective device judges that pt branch road is the phase-to phase fault branch road of T link.

Wherein, φ φ=AB, BC, CA phase; Three branch roads of T link are respectively mt branch road, nt branch road and pt branch road; T is the T binding place of three branch road mt branch roads, nt branch road and pt branch roads; Z _c1for electric transmission line positive sequence wave impedance; γ ₁for electric transmission line positive sequence propagation constant; l _mtfor the length of T link mt branch road; l _ntfor the length of T link nt branch road; l _ptfor the length of T link pt branch road; Cosh () is hyperbolic cosine function; Sinh () is hyperbolic sine function.

The inventive method utilizes distributed parameter model to calculate the fault voltage between phases of three branch roads at T binding place respectively; judge that three branch roads phase place of negative-sequence current between the fault phase of the fault voltage between phases of T binding place its protection installation place leading is less than zero and whether sets up respectively; if there is branch road phase place of negative-sequence current between the fault phase of the fault voltage between phases of T binding place its protection installation place leading to be less than zero establishment, then judge that this branch road is the phase-to phase fault branch road of T link.After the inventive method is applicable to T link phase fault, the fault branch of whole failure process differentiates, differentiates result not by the impact of transition resistance, load current and abort situation.During the alternate high resistant short trouble of T link, the inventive method accurately can judge the phase-to phase fault branch road of T link.

The foregoing is only preferred embodiment of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses, the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

Claims (1)

1.T link phase-to phase fault branch road phase judgment method, is characterized in that, comprise following sequential steps:

(1) protective device protector measuring T link is at the fault voltage between phases of m end protection installation place fault three-phase current negative-sequence current between fault phase measure the fault voltage between phases of T link in n end protection installation place fault three-phase current negative-sequence current between fault phase measure the fault voltage between phases of T link in p end protection installation place fault three-phase current negative-sequence current between fault phase wherein, φ φ=AB, BC, CA phase,

(2) protective device judges on mt branch road ${\stackrel{\·}{U}}_{\mathrm{m\φ\φ}}\cosh \left({\mathrm{\γ}}_l{l}_{\mathrm{mt}}\right)-Z_{c1}{\stackrel{\·}{I}}_{\mathrm{m\φ\φ}}\sinh \left({\mathrm{\γ}}_l{l}_{\mathrm{mt}}\right)$ Leading angle be less than zero and whether set up, if set up, then protective device judges that mt branch road is the phase-to phase fault branch road of T link; Wherein, φ φ=AB, BC, CA phase; Three branch roads of T link are respectively mt branch road, nt branch road and pt branch road; T is the T binding place of three branch road mt branch roads, nt branch road and pt branch roads; Z _c1for electric transmission line positive sequence wave impedance; γ ₁for electric transmission line positive sequence propagation constant; l _mtfor the length of T link mt branch road; Cosh () is hyperbolic cosine function; Sinh () is hyperbolic sine function;

(3) protective device judges on nt branch road ${\stackrel{\·}{U}}_{\mathrm{n\φ\φ}}\cosh \left({\mathrm{\γ}}_l{l}_{\mathrm{nt}}\right)-Z_{c1}{\stackrel{\·}{I}}_{\mathrm{n\φ\φ}}\sinh \left({\mathrm{\γ}}_l{l}_{\mathrm{nt}}\right)$ Leading angle be less than zero and whether set up, if set up, then protective device judges that nt branch road is the phase-to phase fault branch road of T link; Wherein, φ φ=AB, BC, CA phase; l _ntfor the length of T link nt branch road; Cosh () is hyperbolic cosine function; Sinh () is hyperbolic sine function;

(4) protective device judges on pt branch road ${\stackrel{\·}{U}}_{\mathrm{p\φ\φ}}\cosh \left({\mathrm{\γ}}_l{l}_{\mathrm{pt}}\right)-Z_{c1}{\stackrel{\·}{I}}_{\mathrm{p\φ\φ}}\sinh \left({\mathrm{\γ}}_l{l}_{\mathrm{pt}}\right)$ Leading angle be less than zero and whether set up, if set up, then protective device judges that pt branch road is the phase-to phase fault branch road of T link; Wherein, φ φ=AB, BC, CA phase; l _ptfor the length of T link pt branch road; Cosh () is hyperbolic cosine function; Sinh () is hyperbolic sine function.