SU761953A1 - Method of short circuit location - Google Patents

Description

The invention relates to the technology of determining the locations of damage to overhead transmission lines by the parameters of the emergency mode (currents and short-circuit voltages). It can be used in high-voltage electrical networks.

Known methods for determining the locations of damage to overhead transmission lines with branches, based on the measurement and fixation of currents and voltages of zero (reverse) sequence at the ends of the line with the subsequent calculation [1,2].

The disadvantage of these methods is the absence in them of an automatic accounting of the regime of branch stations, which leads to additional errors in determining the location of damage. Changing the mode of branch substations depends on the number of transformers connected to them, on the position of the tap changers and the neutral mode of these transformers, as well as on the operating mode of the power systems adjacent to the branches.

The closest in technical essence to the proposed method is

method of determining the distance to the short circuit, based on the measurement and fixation of currents and voltages of zero (reverse) sequence at the ends of the line and currents of zero (reverse) sequence at the substation of branches [3].

This method has the following disadvantages:

a) is suitable only for the mode of parallel operation of the chain of the line and is unacceptable in the modes when the chain of the line operates separately, separately at one or both ends of the line;

b) the distance to the place of damage is calculated by a single calculated expression. Therefore, measurement errors of fixing devices, as well as errors in the reading and transmission of their readings cannot be detected during the calculation; n lead to the issuance of a false result;

c) in the most common mode. In parallel operation of line circuits, the accuracy of the method is not sufficiently high due to the fact that the calculation formulas must take into account the intrinsic and mutual resistance of the transmission line, which is often difficult to take into account with the necessary degree of accuracy.

The aim of the proposed method is to eliminate the above disadvantages.

This goal is achieved by measuring and fixing the geometric sum and the geometric difference between them.

The zero (back?!) sequence of two line circuits, and the sought distance to the fault site is determined by two independent formulas, one of which includes the values of the geometric sums of the currents at the ends of the line, and the other the geometric differences of these currents.

FIG. 1 and 2 shows one of the options for the inclusion of fixing ammeters on the geometric sum Л_. and the geometric difference And implementing the proposed method.

The distance to the line of damage is determined by the following formulas:

ί7 _βί + υ _β2 - // _{L1 ~ ί / Α, + ίΧ +} χ ιη) (/ β + ι +.

¹ (X + X _r) ( '.. 1 _and +

+ ΖιΔι +? ₂ Ζ ._, + · · + /, пГтА-р.пГпί / _β2 —υ _Βϊ - and _А2 + ь ' _А , + (хх, φ [ ^! / Ί -в—

'Tx Ί _Β Σ- ~ "' *

—LA + · · · +7 _yes 6, „)! - (/ ₂ /. ₂ + --.- 1 - /., Е _P )]

- (L + + 1, p) + (7> -ί- · · -g / _l )] ''

where / ₂ - the distance from the substation A to the point of short circuit;

Δ is the length of the line;

Il Π V P _A2 , and _B2 - voltage zero (reverse) sequence at the ends of the first and second circuits at substations A and B;

1a +, / b +> / a-, Sv- is the sum and difference of the currents of the zero (inverse) sequence of two circuits, measured at substations A and B;

L, ... 1 _t - currents of zero (reverse) sequence in the branches connected to the intact circuit;

'1 ₂ , - currents of zero (reverse) sequence in the branches connected to the damaged circuit;

L ₂ , ... L _t , are the distances from substation A to the corresponding branches on the line;

X, X _t - specific intrinsic resistance of each circuit and the specific resistance "mutual induction between the circuits in the equivalent circuit of the zero (reverse) sequence.

In the parallel operation mode of the chains, the calculation formula (2) is significantly simplified and takes the form:

/ d - /. · · · + /, „/ -,“) - (/.,5. ,+. ·· -) - /

- (L + ‘· T L; g) x (B - · · - g / l)

(3)

The formula (3) does not include the values of the eigenn and mutual resistances of the line. Since these parameters can not always be accurately determined, excluding them from the calculation formula makes it possible to increase the accuracy of the result.

Thus, determining the distance to the point of damage to the line by means of two independent design formulas, which include measured geometric sum, among other values. And the difference in current of the zero (reverse) sequence, allows extending the field of application of the method, increasing the accuracy and reliability of determining the desired distance.

Claims (1)

Claim The method of determining the distance to the place of short circuit of a double-circuit transmission line with branches, based on measurement and fixation at the time of a short circuit voltage zero (reverse) sequence at the ends of the line and current zero (reverse) sequence at branch stations and subsequent calculation, characterized in that , in order to expand the scope of application of the method to any full-phase modes of operation of the lines, improve the accuracy and reliability of determining the distance to the site of damage, at the end line is measured and fixed geometrical sum "and the difference of the zero currents (reverse) sequences of the two line circuits, and the desired distance to the fault is determined from the two formulas: In B1 + In P2 - £ / _Л 1 - В _А2 + (X- Х _т ) (1 _{d +} (X + Xm) And _A + A-1b + + -5A - /,/.,-)-/2/.2+ · - · + / _t 5 _t + 1 _p L _p ) + Λ + Λ + · · · + / _lg + / _l ) ' 6'v-2 ~ and b \ In _A2 + ^ A1 A (X—— (X Xm) 0 _A - + —OA- ---- + (47 ₂ + · - / „/. ,,)] - (Λ4— · + + _η ι) + (Λ + · · - + 7 _L )] 761953 where I is the distance from substation A to the point of short circuit; B is the length of the line; five Еа \, υ _Β ι, and _А 2, are the voltages of zero (reverse) sequence at the ends of the first and second circuits at substations A and β; / а +, / в +, / а-, 1в- - the sum and difference of the currents of the zero (inverse) sequence of two circuits, measured on substations A and B; C, ... 1 _t - currents of zero (reverse) sequence in response to 20 events connected to the intact circuit; 1 ₂ , ... 1 _p - currents of zero (reverse) sequence in the branches connected to the damaged circuit; C, b ₂ , ... b _t , e _p are the distances from substation A to the corresponding branches on the line; X, X _t - specific resistivity,, each chain and the mutual resistance of the inductance between the circuits in the equivalent circuit of the zero (inverse) sequence.