CN101877480A - Method for judging voltage compensation of single-pole adaptive reclosure of electric transmission line - Google Patents

Abstract

The invention discloses a method for judging the voltage compensation of a single-pole adaptive reclosure of an electric transmission line, which comprises the following steps of: 1) defining a fault phase through a phase selecting component in a line protecting device; 2) computing a computation fault phase terminal voltage value when having the temporary fault under the current system running state through a temporary fault model, and subtracting a practically-measured practical fault phase terminal voltage value to obtain a differential value; 3) judging to be a temporary fault and exporting the reclosure if the differential value computed in the step 2) is less than a set value; and 4) judging to be a permanent fault and not overlapping the reclosure if the differential value computed in the step 2) is larger than the set value. By setting the temporary fault model, and judging the temporary fault and the permanent fault with the differential value between the computation fault phase terminal voltage value and the practical fault phase terminal voltage value, the method can judge the property of the fault only with single terminal quantity without opposite-side information.

Description

The voltage compensation method of discrimination of transmission line single-phase adaptive reclosing

Technical field

The present invention relates to power system transmission line relaying protection field, particularly relate to a kind of not with the transmission line single phase autoreclosing control method of shunt reactor.

Background technology

The automatic reclosing technology is one of important measures that guarantee power system security power supply and stable operation.Because the fault overwhelming majority who takes place on the extra high voltage network is a transient fault, after fault is eliminated, circuit is put into operation again, can effectively improve the stability of electric power system and to user's power supply quality, so the automatic reclosing technology has obtained in present electric power system using widely.In the various faults that power circuit takes place, single phase ground fault occupies more than 80% approximately, and therefore studying the single phase autoreclosing technology is to have very much realistic meaning.But present single phase autoreclosing technology all is behind circuit breaker trip, postpones the back through the set time and blindly overlaps, and will bring for the second time to electrical network and impact if coincide with permanent fault, its extent of injury even may surpass under normal circumstances short trouble.If therefore can before breaker closing, accurately judge the nature of trouble of transmission line, make circuit breaker only coincide with transient fault and will have great practical significance.

After the single-phase adaptive reclosing technology utilizes fault to disconnect mutually exactly, come the character of failure judgement disconnecting the electric parameters feature go up mutually, to determine whether reclosing overlaps, that is: when being judged as transient fault, line fault allows to overlap, and do not allow to overlap the blindness of so just having avoided reclosing to move when being judged as permanent fault.At present, the method for discrimination of single-phase adaptive reclosing mainly contains at not with the voltage diagnostic method of shunt reactor transmission line with at the current judgement method of band shunt reactor transmission line.The voltage diagnostic method utilizes the capacitor coupling voltage characteristic to distinguish transient fault and permanent fault, and its sensitivity and transition resistance, line length are all relevant, owing to be subjected to the influence of electromagnetic coupled voltage, there is the possibility of erroneous judgement in the voltage diagnostic method.And for the influence of the transmission line of being with shunt reactor owing to shunt reactor, disconnect the electric parameters that goes up mutually and all have the beat frequency characteristic, adopt voltage diagnostic method and current judgement method that the possibility of erroneous judgement is all arranged.Therefore, need the reliable more comprehensively single-phase adaptive reclosing control method of research.

Summary of the invention

The technical problem to be solved in the present invention is, provide a kind of judge by accident probability low, be applicable to the single-phase adaptive reclosing control method of not being with the shunt reactor transmission line, to overcome the deficiency that the prior art scheme exists.

Technical scheme of the present invention is: a kind of voltage compensation method of discrimination of transmission line single-phase adaptive reclosing may further comprise the steps:

1) gathers each phase voltage and the electric current of transmission line one side in real time;

2) carry out fault by the route protection element and select phase;

3) utilize under the current system running state of transient fault Model Calculation calculating fault phase terminal voltage value when transient fault takes place, and with actual measurement to the physical fault phase terminal voltage subtract each other and ask for difference;

4) if the difference in the step 3) less than setting value, then is judged to transient fault, reclosing outlet action; Otherwise, then being judged to permanent fault, reclosing does not overlap;

Described transient fault computation model is

Wherein

Be transient fault Model Calculation phase terminal voltage value,

Be the capacitor coupling voltage of fault phase mid point,

Electromagnetic coupled voltage for the line fault phase.

Described instantaneous point capacitor coupling voltage

Computation model be

Wherein

With

Be non-fault phase voltage, C _mBe the alternate equivalent capacity of circuit, C ₀Be circuit equivalent capacity relatively.

The electromagnetic coupled voltage of described line fault phase Computation model be

Z wherein _mMutual inductance for the transmission line unit length; L is a Route Length, With

Be respectively non-fault phase current.

Setting value

K _kBe safety factor, span is 0.3～0.6.

Compared with prior art, the present invention has the following advantages:

1. the present invention is by setting up a transient fault model, utilize the difference of calculating fault phase terminal voltage value and physical fault phase terminal voltage to judge transient fault and permanent fault, so only utilize single-ended amount can finish the judgement of nature of trouble, the information that does not need offside, make the present invention detect the integrality that does not rely on communication port with the validity of judging, simultaneously do not need fault location device that fault point information is provided, make the control of adaptive reclose can be more safe and reliable.

2. the present invention is applicable to the transmission line of not being with shunt reactor, is not subjected to transmission line length on the principle, position of failure point, and transition resistance size and transmission line perfect the influence of phase load electric current.

Description of drawings

Fig. 1 is that single-phase adaptive reclosing nature of trouble of the present invention is differentiated flow chart;

Equivalent circuit diagram when Fig. 2 is transient fault after the single-phase disconnection;

Fig. 3 be under the transient fault situation circuit both end voltage concern schematic diagram;

Fig. 4 is the vector correlation figure of Fig. 3;

When Fig. 5 disconnects the permanent metallicity fault of phase terminal voltage after compensation during for permanent fault

Schematic diagram;

Fig. 6 disconnect during for permanent fault phase terminal voltage after compensation through the transition resistance R _gDuring permanent earth fault

Schematic diagram;

Embodiment

Below by specific embodiment, describe technical scheme of the present invention in detail.

(1) the electric parameters feature during single-phase transient fault

As shown in Figure 2, be example with the A phase fault, fault disconnected mutually when transient fault took place, and behind the short dot arc extinction, circuit transfers the two-phase operation state to.There is capacitor coupling voltage in fault mutually and between the sound phase

With electromagnetic coupled voltage The fault phase terminal voltage is

With

The vector sum,

With

Be respectively:

${\stackrel{\·}{U}}_y=({\stackrel{\·}{U}}_B+{\stackrel{\·}{U}}_C)\frac{C_m}{C_0+2C_m}---\left(1\right)$

${\stackrel{\·}{U}}_{\mathrm{xL}}=({\stackrel{\·}{I}}_B+{\stackrel{\·}{I}}_C)Z_{m}L---\left(2\right)$

In the following formula, Z _mMutual inductance for the transmission line unit length; L is a Route Length; C _mAnd C ₀Be respectively alternate equivalent capacity and equivalent capacity relatively.

(2) the electric parameters feature during single-phase permanent fault

During permanent fault, the terminal voltage of faulty line can be regarded the capacitor coupling voltage of fault point as With the electromagnetic coupled voltage of circuit to the fault point

The vector sum.

${\stackrel{\·}{U}}_y^{\′}=\frac{({\stackrel{\·}{U}}_B+{\stackrel{\·}{U}}_C)R_g\left(\mathrm{j\ω}{C}_m\right)}{1+R_g\left(\mathrm{j\ω}\right)(C_0+2C_m)}---\left(3\right)$

${\stackrel{\·}{U}}_{\mathrm{xl}}=({\stackrel{\·}{I}}_B+{\stackrel{\·}{I}}_C)Z_{m}l---\left(4\right)$

In the following formula, Z _mMutual inductance for the transmission line unit length; L is the length of circuit head end to the fault point; C _mAnd C ₀Be respectively alternate equivalent capacity and equivalent capacity relatively, R _gBe earth resistance.

(3) novel voltage of single-phase adaptive reclosing compensation method of discrimination

By Fig. 3 and Fig. 4 as can be known, under the transient fault situation, disconnect the terminal voltage of phase

Can be expressed as:

$\stackrel{\·}{U}={\stackrel{\·}{U}}_y+0.5{\stackrel{\·}{U}}_{\mathrm{xL}}---\left(5\right)$

Make bucking voltage

For:

${\stackrel{\·}{U}}_p={\stackrel{\·}{U}}_y+0.5{\stackrel{\·}{U}}_{\mathrm{xL}}---\left(6\right)$

Then under the transient fault situation, can derive:

$\left|\mathrm{\Δ}\stackrel{\·}{U}\right|=|\stackrel{\·}{U}-{\stackrel{\·}{U}}_p|=|\stackrel{\·}{U}-{\stackrel{\·}{U}}_y-0.5{\stackrel{\·}{U}}_{\mathrm{xL}}|=0---\left(7\right)$

When permanent earth fault, compensate according to the transient fault characteristic equally disconnecting phase terminal voltage, can derive following formula:

$\left|\mathrm{\Δ}\stackrel{\·}{U}\right|=|({\stackrel{\·}{U}}_y^{\′}-{\stackrel{\·}{U}}_y)+({\stackrel{\·}{U}}_{\mathrm{xl}}-0.5{\stackrel{\·}{U}}_{\mathrm{xL}})|>0---\left(8\right)$

As the above analysis, under the transient fault situation, it is 0 that the fault phase terminal voltage adopts the transient fault terminal voltage to measure the compensated voltage amplitude by way of compensation; And under the permanent fault situation, fault phase terminal voltage and bucking voltage do not wait, and the fault phase terminal voltage will be much larger than 0 through the compensated voltage amplitude.Therefore, can basis Transient fault and permanent fault are effectively made a distinction.

When Fig. 5 is permanent metallicity fault

Schematic diagram, as can be seen from Figure, along with the increase (the power-factor angle maximum possible reaches 45 °) of power-factor angle θ, Minimum value under ° situation of θ=45, obtain, that is:

Fig. 6 is through the transition resistance R _gDuring permanent earth fault

Schematic diagram, as can be seen from Figure, owing to be subjected to the influence of transition resistance,

Minimum value

In sum, transition resistance and electromagnetic coupled voltage are to not influence of technical scheme proposed by the invention.

In order to eliminate the influence of factors such as model simplification, the error of calculation, improve the reliability of this method, setting value U _ZDDetermine according to following formula:

$U_{\mathrm{ZD}}=K_k\left|{\stackrel{\·}{U}}_y\right|---\left(9\right)$

In the following formula,

Be capacitor coupling voltage according to real-time calculating under the transient fault situation; K _kBe safety factor, according to the difference of system operation mode, span is K _k=0.3～0.6.

Based on above-mentioned analysis, this paper has proposed a kind of novel voltage compensation method of discrimination of transmission line single-phase adaptive reclosing, and criterion is as follows:

$\left|\mathrm{\&Delta;}\stackrel{\&CenterDot;}{U}\right|=|\stackrel{\&CenterDot;}{U}-{\stackrel{\&CenterDot;}{U}}_p|<U_{\mathrm{ZD}}---\left(10\right)$

If following formula is set up, then be judged to transient fault, reclosing action outlet; Otherwise be judged to permanent fault, forbid the reclosing action.

Flow process of the present invention is as shown in Figure 4:

1) gathers each phase voltage and the electric current of transmission line one side in real time;

2) carry out fault by the route protection element and select phase;

3) utilize under the current system running state of transient fault Model Calculation capacitor coupling voltage when transient fault takes place

Electromagnetic coupled voltage

And setting value U _ZD, the terminal voltage that fault is measured mutually compensates simultaneously

4) if formula (10) satisfies, then be judged to transient fault, reclosing outlet action; If formula (10) does not satisfy, then be judged to permanent fault, reclosing is forbidden overlapping;

As the above analysis, criterion essence of the present invention is to utilize under the transient fault situation fault phase terminal voltage to have clear and definite characteristic to be foundation, and the fault phase terminal voltage that adopts the terminal voltage under this state to measure by way of compensation (comprising permanent fault) under the various failure conditions compensates differentiation.Because the terminal voltage of permanent fault and transient fault has visibly different characteristic after compensation, permanent fault and transient fault effectively can be made a distinction in view of the above.

The principle of the invention is clear, practical, overcome the shortcoming that single-phase adaptive reclosing control method in the past is subject to earth resistance, load current influence, multiple operational mode that can adaptive system, and only utilized the single-ended information of circuit, do not need fault location device, be easy to realize.Therefore, the present invention has important theory value and actual application value.

Claims (5)

1. the voltage compensation method of discrimination of a transmission line single-phase adaptive reclosing, it is characterized in that: this determination methods may further comprise the steps:

1) determines that by the phase selection element in the line protective devices fault is separate;

2) utilize under the current system running state of transient fault Model Calculation calculating fault phase terminal voltage value when transient fault takes place, and with actual measurement to the physical fault phase terminal voltage subtract each other and ask for difference;

3) if step 2) in difference less than setting value, then be judged to transient fault, reclosing outlet action; Otherwise, then being judged to permanent fault, reclosing does not overlap.

2. the voltage compensation method of discrimination of transmission line single-phase adaptive reclosing according to claim 1, it is characterized in that: described transient fault computation model is

Wherein

Be transient fault Model Calculation phase terminal voltage value,

Be the capacitor coupling voltage of fault phase mid point,

Electromagnetic coupled voltage for the line fault phase.

3. the voltage compensation method of discrimination of transmission line single-phase adaptive reclosing according to claim 2 is characterized in that: described transient fault capacitor coupling voltage

Computation model be

Wherein

With

Be non-fault phase voltage, C _mBe the alternate equivalent capacity of circuit, C ₀Be circuit equivalent capacity relatively.

4. the voltage compensation method of discrimination of transmission line single-phase adaptive reclosing according to claim 2 is characterized in that: the electromagnetic coupled voltage of described line fault phase

Computation model be

Z wherein _mMutual inductance for the transmission line unit length; L is a Route Length,

With Be respectively non-fault phase current.

5. the voltage compensation method of discrimination of transmission line single-phase adaptive reclosing according to claim 1 is characterized in that: setting value

Kk is a safety factor, and span is 0.3～0.6.

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