SU684671A1 - Arrangement for automatic connection of synchronous generatoe for parallel operation with mains - Google Patents

Description

The invention relates to electrical engineering and, in particular, to the issues of automatically turning on synchronous generators for parallel operation with a network using proximity switches.

Devices for automatically switching on parallel o operation of synchronous generators using contactless switches (e.g., power thyristors) in main current circuits are known.

The use of thyristors in these circuits improves the quality of synchronization. However, at the present stage of development of semiconductor technology, great difficulties continue to exist in the design of high-power contactless switches. A comparative assessment of dimensions shows an advantage in this respect of contact automata; therefore, in the synchronization schemes under consideration, in order to reduce their overall dimensions, a parallel connection of contactless and contact automata 1 is used.

In the known device, a proximity switch captures the instant of coincidence of the phases of the synchronized generators, ensuring its unloading. The final unloading of the proximity switch is ensured by an additional contact switch connected in series to the power thyristors. In the above scheme, a decrease in the power of the contactless switch is achieved by calculating it for short-term operation.

0 for a time equal to (in the limit) the time of operation of two contact automata (shunt and disconnect).

A disadvantage of the known device is the large installed power of the contactless switch, since the residence time of the contactless switch in the on state is not controlled.

It is also known a device for automatically switching on a synchronous generator for parallel operation with a network, in which a parallel connection of contactless and contact switches 2 is used.

five

The disadvantage of the known device is the unreasonably large installed power of the contactless switch, since after synchronization, when turned on in parallel

Claims (3)

0 contactless and contact switches, about an half of the generator load current flows through the anode circuits of the contactless switch. The closest solution to the technical essence and the achieved result is a device for automatically turning on a synchronous generator for parallel operation with a network, in which the limitation switch 3 is adjusted for the duration of the switch-on time of the contactless switch, one of which is The contact is made with a high-speed contactless starting drive, and the second is contactless, for example, thyristor, and the contactless thyristors are off The switch is turned on in parallel with the contacts of the contact switch. The control unit of the proximity switch is connected to the output of the synchronization unit, the inputs of which are used for connecting to the voltage of the generator and the network. To disconnect the contactless switch, after switching on the contact switch, feedback was established between the control unit of the contactless switch and the contacts of the contact device. On the feedback circuit, a signal is given to turn off the power thyristors. In addition, to increase reliability, a time relay is connected to the output of the synchronization unit, the contact of which is connected to the power supply circuit of the control unit of the proximity switch. The disadvantage of the prototype is that the feedback circuit directly between the contacts of the contact device and the control unit of the proximity switch is difficult with standard elements and, in most cases, unreliable. An insufficiently reliable link is also the presence of a contact time relay. An insufficiently successful circuit design that affects the reliability of the device is the presence of a common control unit for a proximity switch and for driving a contact switch. The aim of the invention is to reduce the power of the contactless switch and increase the reliability of the device, in particular, to increase the reliability of the protection against the overload of the contactless switch. For this purpose, a block of logic incorporated in the current feedback circuit between the power circuits of the contact and contactless switches and the control unit of the contactless switch is inserted into the device. The logic unit consists of a delay element whose input is connected to an input current sensor of a thyristor circuit of a contactless switch, and a prohibition element whose input is connected to an input current sensor of a contact switch circuit, the input of the prohibition element connected to the output of the delay element and the output to the input of the block proximity switch control. The drawing shows a device for automatically switching on a synchronous generator for parallel operation with a network. The device contains a synchronization unit 1, the inputs of which are connected to the mains voltage and the synchronous generator 2, and the outputs are connected to the control unit 3 of the contactless switch 4 and to the high-speed drive 5 of the contact switch 6, the current sensor 7 in the contact switch circuit, the output of which is connected to the input the element 8 of the prohibition of block 9 logic, the sensor 10 current in the circuit of the thyristors of the contactless switch, the output of which is connected to the input of the element 11 of the delay of the logic unit 9. The device works as follows. The synchronization unit 1 detects a moment favorable for switching on the synchronous generator 2, and outputs a signal of the required duration to the control unit 3 of the contactless switch 4 and the high-speed drive 5 of the contact switch 6. Due to the speed of the thyristors, the contactless switch operates first and then the contact contacts close the switch. When this sensor 7 current captures the moment of contact closure and sends a signal to the input element 8 of block 9 logic. The prohibition element 8 generates a pulse for switching off (the prohibition of switching on) the contactless switch. In order to prevent unacceptable overload of the power thyristors of the contactless switch in case of failure of the contact switch, for example, if an open circuit of the high-speed actuator 5 is open, a sensor 10 is provided, which through the delay element 11 also sends a signal to the inhibit element 8. The time delay of the signal is equal to the estimated time taken when choosing the power of the power thyristors of the contactless switch. A new set of elements makes it possible to create a device with reliable current feedback circuits made on standard contactless logic elements and thereby increase the reliability of synchronization. Separation of the circuits of the control unit 3 and the high-speed drive 5 allows the generator to be switched on to the network only by means of a contact switch 6, for example, if there is a malfunction in the contactless circuit of the circuit breaker (emergency start). 5 In addition, the high speed actuator 5 can be used not only for switching on, but also for switching off the contact switch. In the prototype type, an additional proximity switch, used only to turn on a contact switch, is turned off immediately after connecting the generator to the network. Formula of the Invention A device for automatically turning on a synchronous generator for parallel operation with a network, containing three-phase circuit breakers in the generator circuit, one of which is made with a contact with a fast acting drive, and the second is contactless, for example, thyristor-C, with the contactless thyristors connected in parallel contact switch, and the control unit of the proximity switch and the high-speed drive of the contact switch are connected to the output of the synchronization unit Connections with output terminals for connection to the direction of the generator and the network, characterized in that, in order to reduce the installed power of the contactless switch and increase reliability, the device is equipped with a logic unit consisting of a delay element whose input is connected to the input terminal; a thyristor circuit of a contactless switch and an inhibition element, the input of which is connected to an input current sensor of a circuit switch circuit and to an output of a delay element, and the output of an inhibit element is connected to the input of the unit pack ION proximity switch. Sources of information taken into account in the examination 1. Sat. Ship Electrical Engineering and Communications, 33-34 L., 1967, p. 20. 2. Authors certificate of the USSR 244476, cl. H 02 J 3/40, 1967. 3. Forward 2418286 / 24-07, cl. H 02 J 3/42, 1976, according to which a positive decision was made on the issue of auth. swith