RU2669542C1 - System of selective blocking of automatic reclosing on combined aerial cable transmission lines - Google Patents

Abstract

FIELD: electricity.SUBSTANCE: invention relates to electric power industry, in particular, to relay protection and automatic equipment (RPA) with a function of automatic reclosing (AR) of electric power transmission lines, and can be used in relay protection systems of combined aerial cable transmission lines (ACTL), performed with a function of prohibition of automatic reclosing for damages on the cable section of ACTL. System comprises device 5 of prohibition of reclosing located on substation 4 and sensor 6 of the total screen current with optical signal manipulator 7 located at the end of cable section 1, and may also comprise second sensor 12 similar to sensor 6 and second manipulator 13 similar to manipulator 7 located on the opposite side of section 1. Control inputs 8 of manipulators 7 and 13 are connected to the outputs of sensors 6 and 12. Fiber optic line 9 connects device 5 to manipulators 7 and 13. Device 5 is provided with source 10 and receiver 11 of optical radiation. Fiber optic line 9 is made in the form of a loop connecting source 10 and receiver 11. Line 9 passes through manipulators 7 and 13, which are configured to interrupt the optical radiation when the unipolar threshold is exceeded by instantaneous values of the output currents of sensors 6 and 12, respectively.EFFECT: simplifying and increasing the reliability of an AR blocking system, as well as expanding the area of its application to ACTL with increased distance of cable sections from substations and with a longer length of cable sections.6 cl, 9 dwg

Description

The invention relates to the electric power industry and, in particular, to relay protection and automation systems (RPA) with the function of automatic re-activation (AR) of power lines and can be applied in relay protection systems of combined cable-overhead power lines (KVL) performed with the prohibition function Automatic reclosure in case of damage on the cable section of the cable line.

State of the art

When the relay protection system performs the automatic reclosure function on the waterline, the task arises of determining the area (cable or air) on which the damage occurred.

In the event of damage in the KVL air section, the use of the automatic reclosure line is an effective way to quickly restore power to consumers, and in the event of damage to the KVL cable section, the use of the reclosure is not only useless, but even harmful, since it leads to even greater damage to the insulation of the cable section.

A reclosure device is known for CVL, which determines the location of damage (WMD) on the CVL during a dead time pause of reclosure [RU 165635]. In this case, the damage site is first determined by the passive wave method, and then specified by the method of active sensing. The device allows ARs in the event that the damage site specified in the indicated manner is located in the overhead section of the power transmission line.

However, such a WMD, performed in a short time of an automatic reclosure pause, has a significant methodological error, which can lead (especially in the case of damage near the boundary of the cable and air sections of the cable line) to an automatic reclosure prohibition in case of damage in the air section or an incorrect reclosure resolution in case of damage on a cable plot with the corresponding consequences - violation of power supply to consumers or destruction of cable. In addition, the use of this WMD is not possible for some configurations of HFL, for example, for the case when the cable section is between two air sections.

In the work of M. Dmitriev [“Automatic re-activation on 110-500 kV HVL” in railway “ELECTRIC POWER. Transmission and distribution ”No. 1 (28) January-February 2015, pp. 86-91] shows the theoretical possibility of determining the presence of damage on the cable section of the cable line by the magnitude and direction of the total current of the grounded screens of the three phases of the cable section of the cable line. However, the published technical solutions that implement this feature are not known to the applicant.

As a prototype of the claimed control system, a technical solution is selected, described in published international application WO 2015/0333001 G01R 15/24 of 03/12/2015. In the prototype, the recognition of damage on the cable section of the cable line is performed by determining the differences in currents flowing in each phase of the line at the ends of the cable section, and then analyzing these differences. To do this, magneto-optical phase current sensors placed on the line on opposite sides of the cable section are connected by fiber-optic communication cables to the AR inhibitor measuring device installed on the terminal substation and comparing the values and directions of the currents on the sides of the cable section. Fiber-optic communication cables are laid parallel to the power cable in the cable section of the cable line, and in the air section in the lightning protection cable. Two optical fibers are used to connect each current sensor.

The disadvantages of the prototype are the difficulty of performing remote measurement of currents, the high cost of the system and the presence of strict restrictions on the maximum distance between the AR inhibitor measuring device and magneto-optical current sensors, which reduces the scope of this solution.

Disclosure of the invention

The technical result of the invention is to simplify and increase the reliability of the automatic reclosure blocking system, as well as expanding the scope of its application on the HFL with increased remoteness of cable sections from substations and with longer cable sections.

The subject of the invention is a system for blocking automatic reclosure of a cable-overhead power line, comprising an automatic reclosure inhibitor located at a substation, a sensor for the total grounding current of the screens of the cable section, an optical signal manipulator connected to the control input to the output of the specified sensor, and a fiber optic cable a line connecting the specified manipulator and the prohibition device, while the prohibition device is equipped with an optical source and receiver radiation, the optical fiber line is made in the form of a loop connecting the specified source and receiver, the specified manipulator is configured to interrupt optical radiation in the optical fiber line when the unipolar threshold is exceeded by the instantaneous value of the total grounding current of the screens of the cable section, and the indicated prohibition device can compare the duration each pause in the received pulsed optical radiation with a given minimum pause duration and generate an AR inhibit signal when pol itelnom result of the comparison.

This allows you to get the specified technical result.

The invention has a development consisting in the fact that:

- the specified minimum pause duration is set within 0.1 ÷ 0.5 of the industrial frequency period;

The invention has developments related to the case of two-sided grounding of the screens of the cable section and consisting in the fact that:

- the system further comprises a second sensor of the total grounding current of the screens of the cable section located on the opposite side of the cable section and a second optical signal manipulator connected by a control input to the output of the second sensor and configured to interrupt optical radiation in the fiber optic line when the unipolar threshold is exceeded by the instantaneous value of the total grounding current screens of the cable section, while the ban device is made with the additional possibility of comparing s duration of each pause in the received optical radiation of a predetermined maximum pause duration, a pulse duration of optical radiation - with a predetermined minimum pulse duration, pulse period of the optical radiation - with a predetermined minimum period and inhibiting signal to form auto-reclosing at the positive results of these comparisons.

- the maximum pause duration is set within 0.5 ÷ 1.0 of the industrial frequency period, the minimum pulse duration is within 0.1 ÷ 0.5 of the industrial frequency period, the minimum period is within 0.5 ÷ 1.0 of the industrial frequency period .

The invention has developments related to the cases of unilateral and bilateral grounding of the screens of the cable section and consisting in the fact that

- the AR prohibition device is configured to generate a malfunction signal in the absence of optical radiation at the input of the receiver for a long time.

- the manipulators are configured to automatically adjust the unipolar threshold to compensate for the effect of the damped aperiodic component of the total grounding current of the shields of the cable section on the duration of the pauses of optical radiation.

Brief Description of the Figures

In FIG. 1 and FIG. 2 presents the inventive system for cases with unilateral and bilateral grounding of the screens of the cable section, respectively. In FIG. 3, 4, and 5 are signal diagrams illustrating the operation of the system. FIG. 6 illustrates the process of automatically adjusting the response threshold of optical radiation manipulators. FIG. 7 and 8 illustrate the algorithms of the automatic reclosure prohibition implemented by the system. FIG. 9 illustrates the conventions used in FIG. 7 and 8.

The implementation of the invention in view of its development

In FIG. 1 and FIG. 2 shows a three-phase HFL with a cable section 1 and two air sections 2. A HFL connects substation 3 with substation 4. FIG. 1, section 1 has unilaterally earthed cable shields of three phases, and in FIG. 2 - bilateral.

The AR blocking system illustrated in FIG. 1, comprises an AR blocking device 5 located at substation 4 and a sensor 6 of the total screen grounding current located at the end of the cable section 1 and an optical signal manipulator 7.

Depending on the design of the screen grounding device at the end of the cable section, the sensor 6 can be performed in different ways:

- in the form of three current transformers installed in separate ground circuits of the shields of phase cables, the output windings of which are connected in parallel to sum their currents:

- in the form of a single current transformer installed in a common ground circuit of three cable phase shields.

The control input 8 of the manipulator 7 is connected to the output of the sensor 6, i.e. to three summing output windings of current transformers during the first execution of the sensor 6 or to one output winding of the current transformer during the second execution of the sensor 6.

Fiber optic line 9 connects the device 5 with the manipulator 7. The device 5 is equipped with a source 10 that produces continuous optical radiation, and a receiver 11 of optical radiation. Fiber optic line 9 is made in the form of a loop connecting the source 10 and the receiver 11 located in the device 5, and passing through the manipulator 7, remote from the device 5.

The manipulator 7 is a switch of the optical signal of line 9, controlled by the current of the sensor 6 and not requiring any other power supply for its functioning. The manipulator 7 is configured to interrupt the optical radiation passing through line 9 if the instantaneous value of the total current measured by the sensor 6 exceeds a unipolar threshold (i.e., a threshold specified for a current in one direction). The current of a different direction at the output of the sensor 6 is not perceived by the manipulator 7 and does not interrupt the optical radiation in line 9.

The AR blocking system illustrated in FIG. 2 contains all the elements shown in FIG. 1, and additionally a second sensor 12, similar to sensor 6, and a second manipulator 13, similar to manipulator 7, located on the opposite side of the cable section 1. To the output of the sensor 12 is connected the control input of the manipulator 13. The manipulator 13, like the manipulator 7, is configured to interruption of optical radiation in line 9 when the unipolar threshold is exceeded by the instantaneous value of the total grounding current of the screens.

The system with one-sided grounding of the shields of the three phases of the cable section 1 shown in FIG. 1, works as follows.

From the source 10 along the loop line 9 passing through the manipulator 7, the optical radiation transmitted by the receiver 11 is transmitted.

In the absence of damage on the cable section 1 and with external damage to the section 1 on the cable lines, current through the open-ended circuit in the absence of damage does not leak unilaterally grounded cable shields. The output current of the sensor 6 is close to zero, and the manipulator 7 passes radiation to the receiver 11 without change.

In the event of damage on cable section 1 (short circuit between the phases of single-phase cables from which the high-voltage cable sections of the high-voltage cable lines are run, it is practically excluded, and the most probable type of damage is the shorting of the phase cable core to the screen) on the screen of the damaged cable phase through the grounding point in section 1 current flows. As a result, the total current of the screens measured by the sensor 6 is not equal to zero and reaches a value close to the current of the damaged phase. In this case, the instantaneous values of the output current of the sensor 6 exceed the established unipolar threshold on some part of the floor of the industrial frequency period.

In FIG. 3a shows an example of a waveform of the total current of the shields (I _eqΣ ) flowing into the ground circuit and measured by the sensor 6 in case of damage on the cable section 1 with one-sided grounding. The current I _ecΣ may contain the damped aperiodic component of the transient damage process that has occurred on the HFL.

When the instantaneous value of the current I exceeds the set _ekrΣ unipolar threshold (I _ust.poroga) arm 7 controlled by a current sensor 8, entry 6, interrupts the optical radiation to the loop line 9 in the same (positive) half cycle of the power frequency. As a result of such an interruption, pulsed optical radiation with pauses and pulses arrives at the input of the receiver 11, the repetition period of which is equal to the period of the industrial frequency (Fig. 3b).

The device 5 analyzes the pulsed optical radiation arriving at the receiver 11, comparing (for detuning from short-term interference) the duration of each pause in the signal with the specified minimum pause duration, and when it is exceeded, it generates an AR inhibit signal to the relay protection relay protection system or to the control device of the switch.

The system with two-sided grounding of the shields of the three phases of the cable section 1 shown in FIG. 2, works as follows.

From the source 10 along the loop line 9 through the manipulators 7 and 13 is transmitted optical radiation, perceived by the receiver 11.

In the absence of damage to the HFL, the sum of the currents induced in the grounded screens is close to zero. In case of external damage to section 1, the short-circuit current of one direction flows through both ends of section 1, and a non-zero sum of the currents induced in them flows through a closed circuit of bilaterally grounded cable shields. In this case, the sensors 6 and 12 in the same half-period of industrial frequency record the total ground currents I _ekr1 and I _{ekr2 of} different directions - flowing into the earth conductor and flowing out of it.

Accordingly, the manipulators 7 and 13 interrupt the radiation in line 9 at various half-periods of industrial frequency. As a result, the pulsed optical radiation arriving at the receiver 11 has a double frequency (with respect to the industrial frequency), and its period accordingly decreases. The oscillograms of this mode are shown in FIG. 4a and 4b, and the algorithm of operation of the device 5 is illustrated in FIG. 7.

If damage occurs in section 1, currents of different directions flow through its ends in the damaged phase of the line, which induce total currents flowing through the ground conductors in one direction (flowing into the ground or flowing out of it) in the screens. Sensors 6 and 12 provide currents of the same direction in the same half-cycle of industrial frequency. Accordingly, the manipulators 7 and 13 interrupt the radiation in line 9 in the same (for example, positive) half period of the industrial frequency. The diagrams of this mode correspond to FIG. 5a and 5b, and the algorithm of operation of the device 5 is illustrated in FIG. 8.

In both of the above cases of grounding the shields of the cable section 1, the device 5 (as in the case of one-sided grounding of the cable section) analyzes the pulsed optical radiation arriving at the receiver 11, comparing the duration of each pause with the specified minimum pause duration.

In the case of one-sided grounding of cable shields, device 5, with a positive comparison result (pause duration exceeds the minimum), issues a warning signal to the automatic reclosure signal to the KVL relay protection system or to the control device of the KVL switch.

For the case of double-sided grounding of the screens, the analysis of the pulsed optical radiation received by the receiver 11 carried out by the device 5 further includes comparing the duration of each pause with a given maximum pause duration, comparing the pulse duration with a given minimum pulse duration and comparing the period of pulsed optical radiation (equal to the sum of the pause and pulse durations ) with a given minimum period. With the positive results of all these comparisons, the device 5 issues a warning signal to the automatic reclosure signal to the KVL relay protection system or to the control device of the KVL switch.

If the result of any of the above comparisons is negative, device 5 does not generate an AR inhibit signal.

In addition, the device 5 does not give a signal to prohibit the reclosure when fulfilling the monitoring conditions that fix the malfunction of the optical path or the device 5 itself.

At the same time, the indicated minimum pause duration of optical radiation can be set within 0.1 ÷ 0.5 of the industrial frequency period, the maximum pause duration can be set within 0.5 ÷ 1.0 of the industrial frequency period, and the minimum optical pulse length can be within 0.1 ÷ 0.5 period of industrial frequency, and the minimum period is within 0.5 ÷ 1.0 period of industrial frequency.

The health of the optical path (lines 9 and manipulators 7 and 13) can be controlled by the presence of continuous optical radiation at the input of the receiver and the mode preceding the damage. When the disappearance of optical radiation at the input of the receiver 11, for example, for more than five periods of industrial frequency, the device 5 generates a malfunction of the optical path.

To compensate for the influence of the damped aperiodic component of the total grounding current of the shields of the cable section on the duration of the pauses of optical radiation, the manipulators 7 and 13 can be configured to automatically adjust the unipolar threshold. Auto-tuning can be carried out as follows. If, for example, the manipulator works with a unipolar threshold I of the _threshold (see Fig. 6) of a positive sign, then the duration Δt of the negative half-wave of the output current of the sensor connected to the control input of the manipulator is measured. For this, a comparator can be used with a threshold I of a _zero threshold close to zero (indicated by a dotted line in FIG. 5). If the duration Δt exceeds the half-period of the industrial frequency (negative aperiodic component), then the value of I _{set threshold} in the control circuit of the manipulator decreases. After the measured time Δt becomes close to the duration of the half-period of the industrial frequency, the unipolar threshold of the manipulator control circuit returns to its original value. If the measured time Δt is less than the half-period of the industrial frequency (positive aperiodic component), then the I _{set threshold} remains unchanged.

As can be seen from the foregoing, the claimed system of selective blocking of automatic reclosure on the waterline is much simpler and more reliable than the prototype.

The prototype uses magneto-optical current meters in each phase of the line and it is necessary to accurately transmit the currents measured from different sides of the cable section of the cable line through the optical fiber bundle to the ARB inhibitory measuring device installed at the substation, which analyzes the phase-phase differences of the measured currents.

The claimed system uses a single-fiber loop line with one or two optical manipulators installed in the grounding points of the cable sections of the cable lines and controlled by the corresponding total grounding currents of the cable screens.

длиной и

удаленностью кабельных участков от подстанций, поскольку в ней, в отличие от прототипа, оптическое излучение в оптоволоконной линии 9 не используется для измерения значений тока и, следовательно, к стабильности уровня и к затуханию излучения не предъявляется жестких (прецизионных) требований. Расстояние от устройства 5 до манипуляторов 7, 13 с датчиками 6, 12 ограничивается только мощностью оптического источника 10 и чувствительностью оптического приемника 11.The inventive system can be successfully applied to the design waterline with

length and

the remoteness of the cable sections from the substations, since in it, unlike the prototype, optical radiation in the fiber optic line 9 is not used to measure current values and, therefore, there are no strict (precision) requirements for level stability and radiation attenuation. The distance from the device 5 to the manipulators 7, 13 with sensors 6, 12 is limited only by the power of the optical source 10 and the sensitivity of the optical receiver 11.

Claims (6)

1. The system for blocking the automatic restart of the cable-overhead power line, comprising an automatic restart inhibit device located at the substation, a sensor for the total grounding current of the screens of the cable section, an optical signal manipulator connected to the control input to the output of the specified sensor, located on one side of the cable section of the power line , and a fiber optic line connecting said manipulator and a prohibition device, wherein the sn prohibition device Abzhen source and receiver of optical radiation, the optical fiber line is made in the form of a loop connecting the specified source and receiver, the specified manipulator is configured to interrupt optical radiation in the optical fiber line when the unipolar threshold is exceeded by the instantaneous value of the total grounding current of the screens of the cable section, and the specified prohibition device - with the ability to compare the duration of each pause in the received pulsed optical radiation with a given minimum pause duration and f rmirovat signal disable automatic restart in case of positive result of the comparison. 2. The system according to p. 1, characterized in that the specified minimum pause duration is set within 0.1 ÷ 0.5 period of the industrial frequency. 3. The system according to claim 1, characterized in that it further comprises a second sensor of the total grounding current of the screens of the cable section and a second optical signal manipulator located on the opposite side of the cable section, connected by a control input to the output of the second sensor and configured to interrupt optical radiation in fiber line when the unipolar threshold is exceeded by the instantaneous value of the total grounding current of the shields of the cable section, while the prohibition device is made with an additional itelnoy opportunity to compare the duration of each pause in the received optical radiation to a predetermined maximum pause duration, the duration of the optical radiation pulse - with a predetermined minimum pulse duration, the period of the pulsed optical radiation - with a predetermined minimum period and generate a signal disable automatic reclosing case of positive results of said comparisons. 4. The system according to claim 3, characterized in that the minimum pause duration is set within 0.1 ÷ 0.5 of the industrial frequency period, the maximum pause duration is within 0.5 ÷ 1.0 of the industrial frequency period, the minimum pulse duration is within 0.1 ÷ 0.5 period of industrial frequency, the minimum period is within 0.5 ÷ 1.0 period of industrial frequency. 5. The system according to claim 1 or 3, characterized in that the device for prohibiting automatic re-activation is configured to generate a malfunction signal with a prolonged absence of optical radiation at the input of the receiver. 6. The system according to claim 1 or 3, characterized in that the manipulators are configured to automatically adjust the unipolar threshold to compensate for the effect of the damped aperiodic component of the total grounding current of the cable section screens on the duration of the pauses of optical radiation.

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