RU2017298C1 - Method of single-phase automatic reclosure of aerial power line - Google Patents

Abstract

FIELD: electrical power engineering. SUBSTANCE: in case of single-phase short-circuit in superhigh voltage power line network composed of resistor and compensating reactor is connected in neutral of shunting reactors installed in line prior to disconnection of injured phase where resonance overvoltages emerge. EFFECT: enhanced reliability and stability. 1 dwg

Description

 The invention relates to electrical engineering and can be used to increase the efficiency of single-phase automatic repeated switching (OAPV) of ultra-high voltage power transmissions with shunt reactors (SR), in which resonant overvoltages occur on the disconnected phase in the OAPV cycle.

 There is a known OAPV method for a power line equipped with means for compensating the secondary arc recharge current, for example, four-beam reactors, in which, in the event of a single-phase short circuit (short circuit), the damaged phase is disconnected from both ends of the line, suppressed as recharge arcs and, after a predetermined time, repeatedly turn on the disconnected phase from both ends of the line [1].

 The disadvantage of this method is the possibility of resonant voltage rises on the disconnected phase in the OAPV pause for certain combinations of capacities of shunt reactors and line capacitance, which leads to the extinction of the arc feed current.

 There is also a method of OAPV power lines equipped with SR, which consists in the fact that the elimination of resonant conditions on the disconnected phase in a pause OAPV is achieved by disconnecting part of the SR [2].

 The disadvantages of this solution are an increase in the make-up current due to a decrease in the compensation of the interphase capacitance when disconnecting four-beam reactors, as well as the additional resource consumption of the SR switches.

 Closest to the proposed one is a method of limiting the charge current of the secondary arc during the OAW of the power line, according to which, after fixing the fault, the damaged phase of the line is turned off by linear switches, and in the neutral of the SR include a resistor and a compensation reactor connected in series [3].

 The disadvantage of this method is that the input of the active resistance is carried out after the appearance of a resonant increase in voltage on the disconnected phase, which can lead to overlapping insulation of the line or equipment until the resistor is turned on. In addition, a significant amount of active resistance is required for resonance detuning at the disconnected phase, which will significantly reduce the possibility of quenching the make-up current due to the appearance of a noticeable phase shift of the current in the reactor from the capacitive component of the line make-up current.

 The aim of the invention is to reduce the magnitude of the feed current of the arc and the detuning of the resonant conditions in the mode OAPV.

 The goal is achieved by reducing the voltage on the disconnected phase by determining the magnitude of the recovering voltage on the disconnected phase during OAPV according to well-known formulas and turning on the chain of series-connected compensation reactors and active resistances until the line switches are turned off when the permissible voltage on it is exceeded.

 As an example, we consider the implementation of the proposed method for a 500 kV power transmission with a length l = 370 km with two ballasts at the ends.

 The drawing shows one of the possible structural schemes of power transmission that implements the proposed method.

 The power transmission contains a starting system 1 and a receiving system 2, linear switches 3, 4, 5 of the phases A, B, C of the starting system, linear switches 6, 7, 8 of the phases C, A, B of the receiving system, switches 9, 10, 11 of the phases SHR 12 , 13, 14 and 15, 16, 17 of the starting and receiving systems, respectively, compensation reactors 18, 19, active resistances 20, 21 and switches 22, 23, shunt circuits of series-connected compensation reactors and active resistances.

At a given line length, resonant voltage increases occur on the disconnected phase in the OAPV cycle. First, the recovery voltage at the disconnected phase for a given line is determined without taking into account the compensation reactors and when the compensation reactors are included in the neutral of the linear reactors. The calculation is carried out for a line with the following parameters of the direct sequence: X ₁ = 0.30237 Ohm / km (inductive resistance), b ₁ = 3.8217 ˙ 10 ^-6 Sim / km (capacitive conductivity), Z _w1 = 281.3 Ohm ( wave impedance), λ ₁ = 0.0616 deg / km (phase change coefficient) and zero sequence: X _o = 1.082 Ohm / km, b _o = = 2.919 ˙ 10 ^-6 Sim / km, Z _wo = 608.8 Ohm , λ _o = = 0.1018 deg / km.

We take the resistance value of the compensation reactors at the ends equal to X _cr1 = X _cr2 = 180 Ohms. The voltage on the disconnected phase of the line is determined by the expression.

(1)
где

=

-

=

-

B $\genfrac{}{}{0ex}{}{\text{*}}{\text{1}}$ =

+

B $\genfrac{}{}{0ex}{}{\text{*}}{\text{2}}$ =

χ_н=χ_к=

, где В_р - проводимость линейного реактора;
В_кр - проводимость компенсационного реактора;

=

=

;
Δ=(

+B_рн+χ_нB_рн)(

+B_рк+χ_кB_рк)-B $\genfrac{}{}{0ex}{}{\text{*}}{\text{1}}$ ².

(1)
Where

=

-

=

-

B $\genfrac{}{}{0ex}{}{\text{*}}{\text{1}}$ =

+

B $\genfrac{}{}{0ex}{}{\text{*}}{\text{2}}$ =

χ _n = χ _k =

where In _p - the conductivity of the linear reactor;
In _cr - the conductivity of the compensation reactor;

=

=

;
Δ = (

+ B _ph + χ _n B _ph ) (

+ B _pk + χ _to B _pk ) -B $\genfrac{}{}{0ex}{}{\text{*}}{\text{1}}$ ² .

Substituting the above parameters in the expression (1) in the absence of compensation reactors, we obtain the voltage value at the disconnected phase
U _en = 4,56 U _f , i.e. get resonant conditions.

The voltage at the disconnected phase when connecting compensation reactors is determined by the above expression. In this case, U _en = 0.072 U _f , i.e. the inclusion of compensation reactors provides the detuning of resonant conditions.

 If the voltage at the disconnected phase, determined by well-known expressions, exceeds the permissible voltage for isolation of overhead lines and linear equipment, then the compensation reactors are turned on until the line switches are turned off, given that the current flowing through the compensation reactor should not exceed the permissible value in normal mode.

 Thus, the use of the proposed method allows you to upset the resonant conditions for OAPV, keep all linear reactors in operation and reduce the value of the feed current, which will increase the likelihood of a successful AOPV and reduce the economic damage from lack of electricity.

Claims (1)

 METHOD OF SINGLE-PHASE AUTOMATIC REPEATING OF THE ELECTRIC TRANSMISSION AIR LINE, which consists in the fact that after fixing the short circuit, the line switches of the damaged phase are disconnected on both sides, and in the neutral of the shunt reactors they include chains of series-connected compensation reactors and resistors, which determine the difference in voltage phase and when it exceeds the permissible value for the equipment of the chain value from series-connected compensation reactors and resistors in include in the neutrals of the shunt reactors before tripping the line switches.

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