RU2753421C1 - Switchable filter-compensating installation - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention can be used in the field of electrical engineering. The installation contains a main switch, an unregulated and switchable filter section, wherein the switchable section is shunted by a bipolar thyristor with a control electrode, a damping resistor, a current sensor, a differentiation unit, a comparator, a current phase measurement unit and a control unit. Two series-connected resistors and a capacitor are introduced into the installation.

EFFECT: increase in the reliability of the power supply of the traction network with a switchable filter-compensating installation (FCI) by preventing voltage surges and increase in the electromagnetic compatibility of the traction network and the electric rolling stock.

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Description

The invention relates to the electric power industry, in particular to devices for transverse capacitive compensation in an alternating current traction network of a 25 kV and 2 × 25 kV system.

Known adjustable installations of transverse capacitive compensation of reactive power in traction AC networks [1,2,3].

In particular, in [4], a Switched Filter Compensating Unit (FKU) is presented with two unregulated and switchable sections connected in series (a reactor with a capacitor bank is connected in series in each section), and the switchable section is shunted by a switch - a bipolar thyristor. To change the power of the Switched PKU, the switched section is shunted or shunted with a switch, while in [4] it is indicated that this switch can be performed synchronized, for example, using a bipolar thyristor, as is done, in particular, in [3]. When the FKU is shunted, the voltage in the traction network rises abruptly, which can adversely affect the operation of electric locomotives in the traction network. In [5], it was proposed to increase the power of the PKU not abruptly, but step by step, ie. in several steps, changing the opening angle of the thyristor switch in each step. However, at high capacities of the PKU (5-10 Mvar), it will be necessary to increase the number of steps to transfer the voltage mode to another level in order to ensure the permissible operating mode of the electric rolling stock. This will lead to the complication of the thyristor switch control circuit [5]. Therefore, to ensure the electromagnetic compatibility of the traction network and electric rolling stock, it is more expedient to smoothly transfer the voltage of the PKU to the maximum power in the process of switching the Switched PKU with a simplification of the automation circuit and, as a consequence, an increase in its reliability.

So, we take the technical solution [5] as the prototype of the proposed invention and consider A switchable filter-compensating installation containing a series-connected main switch, one end of which is connected to the power bus, an unregulated and switchable filter section, each of which consists of a series-connected reactor and a capacitor bank, and the switchable section is shunted by a bipolar thyristor with a control electrode, a damping resistor shunted a switch, a current sensor, the second end of which is connected to the zero bus, a differentiation unit, the output of which is connected to the control input of the bipolar thyristor, and the input to the output of the comparator, the first input of which is connected to the output of the current phase measurement unit, the input of which is connected to the output of the current sensor , a control unit containing a series-connected electromagnetic relay, an ON button and an OFF button and connected to an operating voltage source, the ON button being bridged by a closing block contact of the electromagnetic relay.

The purpose of the invention is to improve the operational reliability of the Switched FKU and the power supply of the traction network as a whole by preventing voltage surges and increasing the electromagnetic compatibility of the traction network and electric rolling stock.

To realize the purpose of the invention, the following is done:

In a switchable filter-compensating installation containing a series-connected main switch, one end of which is connected to the power bus, an unregulated and switchable filter section, each of which consists of a series-connected reactor and a capacitor bank, and the switchable section is shunted by a bipolar thyristor with a control electrode. a damping resistor shunted by a switch, a current sensor, the second end of which is connected to the zero bus, a differentiation unit, the output of which is connected to the control input of the bipolar thyristor, and the input to the output of the comparator, the first input of which is connected to the output of the current phase measurement unit, the input of which is connected to the output of the current sensor, a control unit containing a series-connected electromagnetic relay, an ON button and an OFF button and connected to an operating voltage source, and the ON button is bridged by a closing block contact of the electromagnetic relay

- additionally two series-connected resistors and a capacitor are introduced, one end of the first resistor through the opening contact of the electromagnetic relay is connected to the positive pole of the operating voltage source, the end of the second resistor is connected to the zero bus, the capacitor is connected by one terminal to the second input of the comparator and the junction point of the resistors, and the second terminal - to the zero bus.

To explain the operation of the invention, we present a diagram (Fig. 1) with the following designations:

1 - main switch;

2 - reactor of the first section;

3 - capacitor bank of the first section;

4 - capacitor bank of the second section;

5 - reactor of the second section;

6 - damping resistor;

7 - bipolar thyristor with a control electrode;

8 - switch, shunt damping resistor;

9 - block of differentiation;

10 - comparator;

11 - unit for measuring the current phase of the filter-compensating installation;

12 - current sensor of the switching filter-compensating installation;

13 - button ON for bypassing the second section to increase the capacity of the PKU,

14 - button OFF for shunting the second section to reduce the capacity of the PKU;

15 - relay for fixing the maximum power mode;

15.1 and 15.2 - make and break contacts of relay 15;

16 - capacitor;

17- the first resistor;

18 second resistor;

19 - block for setting the delay angles at fixed times of switching on the bipolar thyristor;

20 - control unit.

The switchable PKU according to Fig. 1 works as follows. Suppose that in the initial state the FKU operates in the minimum power mode with two sequentially connected sections 2-3 and 4-5, current sensor 12. The maximum power mode fixing relay 15 is disabled, contacts 15.2 are closed. Capacitor 16 is fully charged and the voltage across it exceeds the maximum voltage at the output of the current phase measurement unit 11, corresponding to a 180 ° current phase. There are no signals at the output of the comparator 10. Signals to the bipolar thyristor 7 are not received and it is in the off state.

When the command is given to switch to maximum power by pressing the ON button 13 through the closing contacts of the ON button 13 and through the opening contacts of the OFF button 14, the relay 15 for fixing the maximum power mode is triggered. Through the closing contact 15.1 relay 15 rises to "self-catch". At the same time, its contact 15.2 opens and the capacitor 16 begins to discharge to the resistor 17. The voltage of the capacitor 16, gradually decreasing exponentially, is fed to the second input of the comparator 10, indicated on the diagram by the sign "+". To the first input of the comparator 10, indicated by the sign "-" , a signal with a voltage proportional to the phase of the PKU current comes from the unit for measuring the phase of the current 11.

... When the voltage at the second input of the comparator becomes less than the value corresponding to the current phase of 180 °, the comparator 10 will operate and through the differentiation unit 9 a turn-on signal will be sent to the control input of the bipolar thyristor 7. Bipolar thyristor 7 will turn on when the current phase is less than 180 °, but close to it.

Since the voltage across the capacitor 16 will smoothly decrease, the turn-on angle of the thyristor switch will smoothly decrease from half-cycle to half-cycle from a value close to 180 ° until the thyristor switch opens at a current phase equal to zero. The switching time can be adjusted by changing the value of the capacitance of the capacitor 16. When the phase of the current is equal to zero, the power of the PKU becomes the greatest

When you press the OFF button 14, the second section is bypassed and the capacity and power of the PKU are reduced. When the OFF button 14 is pressed, the relay 15 is turned off, its contacts 15.2 are closed and the capacitor 16 begins to charge through the resistor 18 until the thyristor switch stops opening. Switching to minimum power is also smooth.

Usually, the switching of the power of the FKU occurs automatically when the FKU automatics are operating, then the bipolar thyristor is started not from the ON button, but from the corresponding automatics (not indicated in the diagram).

The technical and economic effect is that with the help of the proposed switchable filter-compensating installation, the voltage smoothly increases and decreases to the required value. At the same time, dangerous voltage surges in the traction network are excluded and the automatic control circuit of the FKU is simplified, which increases the operational reliability and electromagnetic compatibility of the traction network and electric rolling stock.

Literature

1.German L.A., Serebryakov A.S., Dulepov D.E. Filter-compensating installations in traction power supply systems of railways. Monograph. Knyaginino NGIEU, 2017, 402 p.

2.German L.A., Serebryakov A.S., Osokin V.L., Yakunin D.V. Switchable filter-compensating installation in AC traction network. VNIIZhT Bulletin, 2020, v. 79 No. 2 pp. 80-87.

3. Patent No. 2704023 dated March 21, 2019. Three-stage filter-compensating installation of AC traction network (Herman L.A. et al). Publ. 10/23/2019. Bul. No. 30.

4. Patent No. 2475912 dated 09.03.2011. Device for switchable single-phase transverse capacitive compensation in AC traction network. (Serebryakov A.S. and others). Published on February 10, 2013. Bul. No. 5.

5. Patent RU No. 2739329 C1 dated 06.08.2020. Switchable filter-compensating installation. (Serebryakov A.S., German L.A. and others). Publ. 22.122.2020. Bul. No. 36.

Claims (1)

A switchable filter-compensating installation containing a series-connected main switch, one end of which is connected to the power bus, an unregulated and switchable filter section, each of which consists of a series-connected reactor and a capacitor bank, and the switchable section is shunted by a bipolar thyristor with a control electrode, a damping resistor shunted a switch, a current sensor, the second power end of which is connected to the zero bus, a differentiation unit, the output of which is connected to the control input of the bipolar thyristor, and the input to the output of the comparator, the first input of which is connected to the output of the current phase measurement unit of the filter-compensating installation, the input of which is connected to the output of the current sensor, a control unit containing a series-connected electromagnetic relay for fixing the maximum power mode, an ON button and an OFF button connected to an operating voltage source, and the ON button is bridged a closing block contact of an electromagnetic relay, characterized in that two series-connected resistors and a capacitor are introduced into it, and one end of the first resistor is connected to the positive pole of the operating voltage source through the opening contact of the electromagnetic relay for fixing the maximum power mode, the end of the second resistor is connected to the zero bus , the capacitor is connected by one terminal to the second input of the comparator and the junction point of the resistors, and by the second terminal to the zero bus.

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