RU2094924C1 - Process of control over automatic switching on of standby supply - Google Patents

Abstract

FIELD: power supply systems including mainly synchronous motors requiring enhanced reliability of power supply and tolerating no interruptions of it. SUBSTANCE: control instructions are formed directly at object proper where automatics is realized. First instruction to switch on switch of standby power supply source is formed first in time with emergence of injury in power supply network and then for switching off of faulty power supply source by fact of its detection. after its disconnection from external power supply network. Proposed sequence of commands provides for short-time switching on of standby source to unremoved short-circuit simulating circuit with parallel operation of leads-in. EFFECT: enhanced functional efficiency of process.

Description

 The invention relates to power supply to consumers containing mainly synchronous motors (SD), requiring increased reliability of power and not tolerating breaks.

 In the known automatic transfer switch (ATS) devices, in general, two power devices are controlled by an input switch (disconnect damaged input) and a backup source switch (usually the source is connected by a section switch).

 In traditional ABP devices, they first give a command to turn off the input switch, and then to turn on the reserve switch. Traditional ABP usually assumes that during the switching process the LEDs drop out of synchronism with their subsequent self-start.

 At facilities with a traditional ABP, their controls are located at the facility itself. The control method of traditional ABP adopted as an analogue of the invention.

 At some particularly critical facilities, a fast-acting leading automatic transfer switch (BIAA) is used, which during switching prevents the LED from falling out of synchronism, because Compared with traditional ATS, it significantly reduces the interruption time of the power supply in the switching cycle.

 In the method of controlling circuit breakers in the BOAWR cycle, in which the fact of the actuation of high-speed relay protection installed on the head section of the working power supply network (district substation) and which uniquely identifies damaged input is recorded, the command to turn on the reserve is transmitted on the TV channel (see article A.A Galitsyna and A.F. Zadernyuk. Leading AVR at substations of main oil pipelines. J. Industrial Energy, 1986, N 8, pp. 33-36). At the same time, the command to turn off the input and turn on the reserve is common and is applied simultaneously to both switches (input and sectional). The control method is selective, selective.

 The disadvantage of this technical solution is the need to organize a TV channel to transmit the command, which is associated with the installation of relatively expensive and difficult to operate equipment.

 The aim of the invention is to reduce the time of interruption of power supply to values that prevent the LED from falling out of synchronicity during operation of the ATS, without resorting to the construction of television channels (this time is within 0.12 0.20 s see the above article). This goal is achieved by the fact that the start of the automatic transfer switch is carried out until a damaged input is detected (in contrast to the traditional one and BOAWR) upon the occurrence of damage in the supply network. To do this, the order and sequence of receipt of commands for the operation of switches is reversed. In this case, the inclusion of the reserve will occur on an unresolved short circuit (short circuit). The admissibility of such a solution is justified and it has been implemented at a number of industrial facilities (see the indicated article).

 The drawing shows a power supply scheme typical of industrial enterprises.

 Elements 1-7 belong to the receiving substation (PS), 5 and 6 input switches, 7 backup power switch, normally off. Elements 8-11 belong to the main supply (district) PS. Lines 14-17 relate to the external network, 10 and 11 are power supply switches, 12 and 13 are power supply lines. The length of the dashed communication line between buses 8 and 9 is zero when these buses belong to the same MS.

 Consider the work of an analog in this circuit. Let the buses 8 and 9 belong to the same substation, and on line 12 near the circuit breaker 10 a three-phase fault occurred. Section 1 and 2 engines completely lose power. Installed on the receiving PS automatic devices for controlling the automatic transfer switch, responding to electrical parameters in the elements of this PS, record the short circuit in the supply network, but are not able to detect damaged input until the short circuit is turned off by switch 10. This is explained by the fact that the electrical parameters at the receiving PS will be the same for short-circuit at any point near buses 8 and 9. This is short-circuit at the considered point, short-circuit on line 13 near 11, i.e. on the second entry and at other nearby points. Shutdown 10 restores the voltage on buses 8 and 9 from zero to nominal and through the intact input restores the power to section 2 motors. After shutting down 10, the electrical parameters of the receiving PS change sharply, a damaged input is clearly detected, the shutdown command 5 passes, and after that the shutdown command 7.

 The total duration of the power supply interruption for motors connected to 1 will be about 0.3 s. In the estimates of the time, it was assumed that for each operation (operation of relay protection and tripping of circuit breaker 10 in the 110-220 kV network, operation of automatics and shutdown 5, operation of automatics and turning on 7 at a voltage of 6-10 kV), 0.1 s is spent. This operating time corresponds to the parameters of modern equipment. At a power interruption, 0.3 s LEDs fall out of synchronism.

 Consider the work of ABP, using the proposed method. The initial conditions are the same. At the receiving PS, the fact of a short circuit in the supply network is recorded and a command to turn on is issued 7. 0.1 s after the occurrence of a short circuit, it turns off 10. By this moment, it is already closed 7 and on buses 1 and 2 the power direction is set to about 60-70% of the nominal to shutdown time 5, which will occur 0.1 s after shutdown 10. After shutdown 5, the voltage on sections 1 and 2 will become equal to the rated voltage. The total time of the LED power interruption caused by the fact of a three-phase short circuit will be 0.1 s and the operating time with a reduced voltage to 60-70% 0.1 s. Engines will remain in synchronism, i.e. the goal will be reached.

 It is possible to analyze the operation of the ABP for other types and points of short circuit. The proposed method is always effective.

 A feature of the method is that the inclusion of 7 can occur non-selectively, that is, unnecessarily when this is not necessary. Measuring bodies that respond to short circuit in the supply network and located on the receiving PS must reliably fix short circuit, which will lead to loss of input. To do this, they must have sufficient sensitivity with a certain safety factor. So, these bodies will be triggered when short circuits 8 and 9 are removed from lines 14-17, when it is necessary for automatic transfer switch, i.e. in the circuit breaker 7, no. A command to disable inputs 5 or 6 will not follow. Excessive short circuit 7 will be short-term (1-2 s), because after disconnecting the external short circuit and checking the operability of the inputs (for example, upon the fact that the working current flows through them), special automation can command the shutdown 7 and restore the original circuit.

The possibility of implementing the method is not in doubt. We list the cases when the ATS should come into effect:
false (erroneous) shutdown 5, 6, 10, 11;
Short circuit in elements 8, 9, 12, 13, 3 and 4.

 In this case, the ATS should be blocked at a short circuit "below" switches 5 and 6. False shutdowns 5 and 6, as well as damage to transformers 3 and 4, are easily fixed at the receiving substation itself and the implementation of the ATS, which will be selective here, does not cause difficulties.

 With a false shutdown of 10 or 11, the criterion for the operation of the ATS can be, for example, the disappearance of current in the corresponding input at the receiving PS.

 Interphase faults in elements 8, 9, 12, 13 can be fixed using directional resistance relays installed on the receiving PS. The directivity of the relay will prevent them from tripping during short circuits in sections 1 and 2 and below, when the ATS should not come into operation at all.

With a short to ground in elements 8, 9, 12 and 13, the current 3I ₀ in neutrals 3 and 4 can serve as a criterion for the command to turn on 7.

The second command, related to the choice of switch 5 or 6 to be switched off, can be implemented according to the further behavior of the resistance relays or current 3I ₀ mentioned above, after the short circuit is disconnected from the supply PS side, the relays at the intact input will disappear, and at the damaged input they will remain closed.

Claims (1)

 A method for controlling the automatic switching on of the backup power supply, according to which a short circuit is detected in the supply network, a damaged input or a false shutdown of the circuit breaker of this input is detected and a command is generated to turn on the backup power supply and to turn off the specified working input, characterized in that the command to connect the backup power supply form upon the fact of fixing a short circuit in the supply network or upon the false disconnection of the input switch, and the command to disable the working input p the fact of damage detection operation input.