RU2565053C1 - Method for energisation of alternating-current transmission line - Google Patents

Abstract

FIELD: electricity.SUBSTANCE: method is based on energising the first phase, measuring voltage at the second and third phases, checking excess by each measured voltage value of the first control value, and when the result is positive on energising of the second phase, measuring voltage at the third phase, checking excess by each measured voltage value of the second control value, and when the result is positive on energising of the third phase; if the result is negative at checking excess by voltage values measured at the second and third phases of the first control value, the next phases are not energised, the previously connected phase is deenergised, and when a signal is received on available ground fault of the energised first phase it is deenergised and the next phases are not energised; upon energisation of the second and third phases vector difference modules |U| are compared for voltage values of the first and second phases|U| and the first and third phases |U| with low control value of 0.1|U|, where |U| is rated phase voltage, and if condition |U|< 0.1|U| is fulfilled, then fault is recorded for the first and second phases and the first and third phases respectively, thereupon the first and second phases and the third phase are deenergised respectively. Checkup of excess by the first control value of measured voltage values at the second and third phases upon energisation of the first phase and checkups of excess by the second control value of measured voltage values at the third phase upon energisation of the second phase as well as checkups of fulfilled condition |U|< 0.1|U| upon comparison of vector difference modules |U| of the first and second phases |U| and the first and third phases|U|upon energisation of the second and third phases are carried out by series of N checkups in succession since the moment of energisation of the first and second phases and the third phase respectively, at that each series of checkups is made within time period, which duration is equal to N periods of the rated frequency of alternating-current transmission line, and results of checkups of the series are accepted as a bigger number of similar results in majority processing of fixed checkup results in the respective series.EFFECT: expanded scope of application and improved safety for energisation of alternating-current transmission lines.3 cl

Description

The invention relates to the electric power industry and can be used to control the inclusion of an alternating current power line during automatic restart after an emergency shutdown of a line or when putting it into operation.

The known method [RU 2308731 C1, G01R 31/08, 20.10.2007], according to which the state of the insulation of the network and the zero sequence currents in the outgoing lines are monitored, while the insulation level of the network is reduced, a circuit is formed for the short-term passage of the double-fault current to the earth, control the change in the zero sequence currents in the outgoing lines, and if at the moment of the passage of the double-fault current to the earth there is a change in the zero sequence current in one of the outgoing lines, a signal is generated to turn off this line by her earth fault.

The disadvantage of this method is the relatively narrow scope, since it allows you to protect three-phase networks with isolated neutral from single-phase earth faults, but does not allow protection from other undesirable factors, such as short circuits between phases when you turn on the AC power line.

Another analogue of the proposed is a method of switching on a three-phase power line [RU 2358368 C1, НН Н 3/06, 06/10/2009], characterized in that they include the first phase, measure the voltages in the second and third phases, check the excess of the first control value of each of the measured voltages and if the test result is positive, the second phase is turned on, the voltage in the third phase is measured, the excess of the second control value of the voltage measured in the third phase is checked, and if the test is positive, turn on the phase, and with a negative result of any of the checks or the presence of a relay protection signal to turn off the on phase, the subsequent phases do not turn on, and previously turned on - turn off.

The disadvantage of this method is the relatively narrow scope and relatively low security of switching on AC power lines, due, in particular, to the fact that as a result of the procedures (private operations) of the checks, the fact of the closure of the second and / or third phases with the first phase is not revealed.

векторной разности напряжений фаз первой и второй $$\left|U_{12}\right|$$

и первой и третьей $$\left|U_{13}\right|$$

с малой контрольной величиной $$0,1\left|U_{фн}\right|$$

, где $$\left|U_{фн}\right|$$

- номинальное фазное напряжение, и при выполнении условия $$\left|U_{12(13)}\right|<0,1\left|U_{фн}\right|$$

фиксируют замыкание, соответственно, первой и второй и первой и третьей фаз между собой, после чего отключают первую и вторую и третью фазы, соответственно.The closest in technical essence to the proposed one is the method of switching on a three-phase power line [RU 2510115, C1, H02H 3/06, 03/20/2014], based on switching on the first phase, measuring the voltage in the second and third phases, checking if the first control value exceeds each the measured voltages and with a positive result of checking the inclusion of the second phase, measuring the voltage in the third phase, checking the excess of the second control value of the voltage measured in the third phase, and with a positive result of the check switching on the third phase, and if the result of checking the excess of the first control value of the voltage measured in the second and third phases and the excess of the second control value of the voltage measured in the third phase is negative, the subsequent phases do not turn on, and the previously turned on - turn off, and when the signal if there is a short circuit to ground of the first phase, when it is turned on, it is turned off and the subsequent phases are not turned on, after switching on the second and third phases, the modules are compared $$\left|U_{\mathrm{one}2(\mathrm{one}3)}\right|$$

the vector voltage difference of the phases of the first and second $$\left|U_{\mathrm{one}2}\right|$$

and first and third $$\left|U_{\mathrm{one}3}\right|$$

with a small control value $$0,\mathrm{one}\left|U_{fn}\right|$$

where $$\left|U_{fn}\right|$$

- rated phase voltage, and when the condition $$\left|U_{\mathrm{one}2(\mathrm{one}3)}\right|<0,\mathrm{one}\left|U_{fn}\right|$$

fix the closure, respectively, of the first and second and first and third phases to each other, after which the first and second and third phases are disconnected, respectively.

The disadvantage of this closest technical solution is the relatively narrow scope and relatively low security of turning on the AC power line, due, in particular, to the fact that as a result of the operation of the method there is a phenomenon of beating of the induced voltage on the non-connected phases. This phenomenon is not taken into account when implementing the known method. However, it can adversely affect the results of the method and lead to erroneous actions when the AC power line is turned on, including violations of safety conditions.

The problem that is solved in the proposed invention is to expand the scope of the method and increase the security of switching on AC power lines.

The required technical result is to expand the scope and increase the security of switching on AC power lines.

векторной разности напряжений фаз первой и второй $$\left|U_{12}\right|$$

и первой и третьей $$\left|U_{13}\right|$$

с малой контрольной величиной $$0,1\left|U_{фн}\right|$$

, где $$\left|U_{фн}\right|$$

- номинальное фазное напряжение, и при выполнении условия $$\left|U_{12(13)}\right|<0,1\left|U_{фн}\right|$$

фиксируют замыкание, соответственно, первой и второй и первой и третьей фаз между собой, после чего отключают первую и вторую и третью фазы, соответственно, согласно изобретению, проверку превышения первой контрольной величиной измеренных напряжений на второй и третьей фазах после включения первой фазы и проверку превышения второй контрольной величиной напряжения, измеренного на третьей фазе после включения второй фазы, а также проверку выполнения условия $$\left|U_{12(13)}\right|<0,1\left|U_{фн}\right|$$

после сравнения модулей $$\left|U_{12(13)}\right|$$

векторной разности напряжений фаз первой и второй $$\left|U_{12}\right|$$

и первой и третьей $$\left|U_{13}\right|$$

после включения второй и третьей фаз проводят сериями по N проверок подряд от момента включения первой фазы, второй фазы и второй и третьей фаз, соответственно, причем каждую из серий проверок проводят на интервале времени, длительность которого равна N периодам номинальной частоты линии электропередачи переменного тока, а результаты проверок по итогам серии принимают по большему числу одинаковых результатов мажоритарной обработки зафиксированных результатов проверок в соответствующей серии.The problem is solved, and the required technical result is achieved by the fact that, in a method based on switching on the first phase, measuring the voltage in the second and third phases, checking if the first control value exceeds each of the measured voltages, and if the switching on of the second phase is checking positive, measuring the voltage in the third phase, checking the excess of the second control value of the voltage measured in the third phase, and with a positive result of checking the inclusion of the third phase, and with a negative As a result of checking the excess of the first control value of the voltages measured in the second and third phases, and the excess of the second control value of the voltage measured in the third phase, the subsequent phases do not turn on, and previously turned on - turn off when a signal is received about the presence of a short circuit to ground of the first phase its inclusion it is turned off and the subsequent phases do not include, after turning on the second and third phases compare the modules $$\left|U_{\mathrm{one}2(\mathrm{one}3)}\right|$$

the vector voltage difference of the phases of the first and second $$\left|U_{\mathrm{one}2}\right|$$

and first and third $$\left|U_{\mathrm{one}3}\right|$$

with a small control value $$0,\mathrm{one}\left|U_{fn}\right|$$

where $$\left|U_{fn}\right|$$

- rated phase voltage, and when the condition $$\left|U_{\mathrm{one}2(\mathrm{one}3)}\right|<0,\mathrm{one}\left|U_{fn}\right|$$

fix the short circuit, respectively, of the first and second and first and third phases to each other, and then turn off the first and second and third phases, respectively, according to the invention, check the excess of the first control value of the measured voltages in the second and third phases after switching on the first phase and check the excess the second control value of the voltage measured in the third phase after switching on the second phase, as well as checking the fulfillment of the condition $$\left|U_{\mathrm{one}2(\mathrm{one}3)}\right|<0,\mathrm{one}\left|U_{fn}\right|$$

after comparing the modules $$\left|U_{\mathrm{one}2(\mathrm{one}3)}\right|$$

the vector voltage difference of the phases of the first and second $$\left|U_{\mathrm{one}2}\right|$$

and first and third $$\left|U_{\mathrm{one}3}\right|$$

after switching on the second and third phases, a series of N checks is performed in succession from the moment the first phase, second phase and second and third phases are turned on, respectively, each of the series of checks being carried out on a time interval whose duration is equal to N periods of the rated frequency of the AC power line, and the results of inspections based on the results of the series accept for a larger number of identical results of majority processing of the recorded results of inspections in the corresponding series.

In addition, the required technical result is achieved by the fact that the number of checks in the series is either three or five.

In addition, the required technical result is achieved by the fact that checks in series at a time interval whose duration is equal to N periods of the nominal frequency are carried out uniformly.

The operations of the proposed method for switching on an AC power line are performed in the following sequence.

At the command of the power switch control key, any phase that is usually set in advance is switched on.

If the first switched-on phase has a short circuit (SC) to ground, then it is disconnected from the action of relay protection and the switching-on process ends.

Let phase A turn on first. If phase A does not have a short to ground, then it remains on and stress analysis is performed on the other two phases.

(U_фн - номинальное фазное напряжение), то считается что на фазе В(С) КЗ на землю.If, after switching on the first phase (with a delay of the response time for detuning from transients), the level of induced voltage in the other two phases $$\left|{\dot{U}}_{B(C)}\right|\le 0,\mathrm{one}{U}_{fn}$$

(U _fn - nominal phase voltage), it is considered that at phase B (C) a short circuit to ground.

, то это означает замыкание фаз А и В (или фаз А и С) между собой. Процесс включения прекращается, фаза А отключается.To check the absence of short-circuit between phases A and B, as well as A and C, the corresponding phase-to-phase voltages are analyzed. If the modulus of the vector voltage difference of the phases A and B (A and C) $$\left|{\dot{U}}_{AB(AC)}\right|\le 0,\mathrm{one}{U}_{fn}$$

, then this means the closure of phases A and B (or phases A and C) with each other. The start-up process stops, phase A shuts down.

, то замыкания на землю фаз В и С нет. Для проверки отсутствия КЗ между фазами А и В, а также А и С анализируются соответствующие междуфазные напряжения. Если модуль векторной разности напряжений фаз А и В (А и С) $$\left|{\dot{U}}_{AB(AC)}\right|>0,1U_{фн}$$

, то замыкания между фазами А и В (А и С) нет.If the level of induced voltage in phase B (C) $$\left|{\dot{U}}_{B(C)}\right|>0,\mathrm{one}{U}_{fn}$$

, then there are no phases B and C on earth. To check the absence of short-circuit between phases A and B, as well as A and C, the corresponding phase-to-phase voltages are analyzed. If the modulus of the vector voltage difference of the phases A and B (A and C) $$\left|{\dot{U}}_{AB(AC)}\right|>0,\mathrm{one}{U}_{fn}$$

, then there is no short circuit between phases A and B (A and C).

, то фазы В и С замкнуты между собой, процесс включения прекращается, включенные фазы отключаются.If, after switching on the second phase, the induced voltage from two phases (for example, from phases A and B) is the module of the vector voltage difference of phases B and C $$\left|{\dot{U}}_{BC}\right|\le 0,\mathrm{one}{U}_{fn}$$

, then phases B and C are closed to each other, the switching on process stops, the switched on phases are turned off.

,то КЗ между фазами В и С отсутствует и производят включение фазы С.If the modulus of the vector voltage difference of phases B and C $$\left|{\dot{U}}_{BC}\right|>0,\mathrm{one}{U}_{fn}$$

, then the short circuit between phases B and C is absent and phase C is turned on.

In some cases, the phenomenon of induced voltage beating on unconnected phases is observed, which can lead to erroneous actions when the AC power line is turned on, including violations of safety conditions.

To exclude the influence of these beats on the operation of the algorithm, it is proposed to form stress values used for comparison with rates, as follows:

In the time interval from 60 ms to 100 ms, which is the most acceptable and experimentally confirmed and that corresponds, for example, to either 3 or 5 periods of industrial (nominal) frequency from the moment the corresponding phase is turned on, N-fold (N = 3 or N = 5) sequential fixation of the response of the corresponding software voltage measuring organs. Checks in series on a time interval whose duration is equal to N periods of the nominal frequency are usually carried out uniformly in this interval, which is convenient for setting up the corresponding equipment and which increases the reliability of the test results.

The results of the verification based on the results of the series are accepted for a larger number of identical results of majority processing of the recorded results of the checks in the corresponding series.

Moreover, a smaller number of checks, for example one in a series, does not always allow to obtain a reliable final result, and a larger number of checks, for example 7 or more, delays the procedure for obtaining a reliable result without significantly affecting the final result of turning on the AC power line.

Thus, due to the improvement of the known method by using additional operations, the required technical result is achieved regarding the expansion of the scope and increase the safety of switching on AC power lines, due, in particular, to the fact that the influence of beating of induced voltage on unconnected phases is eliminated.

Claims (3)

1. The way to turn on the AC power line, based on the inclusion of the first phase, measuring the voltage in the second and third phases, checking if the first control value exceeds each of the measured voltages and, if the result of checking the switching on of the second phase, measuring the voltage in the third phase, checking the excess of the second the control value of the voltage measured in the third phase, and with a positive result of checking the inclusion of the third phase, and with a negative result of checking the excess of the first the next control value of the voltages measured in the second and third phases, and the excess of the second control value of the voltage measured in the third phase, the subsequent phases do not turn on, and previously turned on - turn off when a signal is received about the presence of a short circuit to ground of the first phase when it is turned on turn off and subsequent phases do not turn on, after turning on the second and third phases compare the modules

the vector voltage difference of the phases of the first and second

and first and third

with a small control value

where

- rated phase voltage, and when the condition

fix the short circuit, respectively, of the first and second and first and third phases to each other, after which they turn off the first and second and third phases, respectively, characterized in that the check that the first control value exceeds the measured voltages in the second and third phases after switching on the first phase and check exceeding the second control value of the voltage measured in the third phase after switching on the second phase, as well as checking the condition

after comparing the modules

the vector voltage difference of the phases of the first and second

and first and third

after switching on the second and third phases, a series of N checks is performed in succession from the moment the first phase, second phase and second and third phases are turned on, respectively, each of the series of checks being carried out on a time interval whose duration is equal to N periods of the rated frequency of the AC power line, and the results of inspections based on the results of the series accept for a larger number of identical results of majority processing of the recorded results of inspections in the corresponding series. 2. The method according to p. 1, characterized in that the number of checks in the series is either three or five. 3. The method according to p. 1, characterized in that the checks in series on a time interval whose duration is equal to N periods of the nominal frequency, are carried out uniformly.