SU1474792A1 - Method for controlling intersystem link - Google Patents

Abstract

The invention relates to power engineering and can be used on AC intersystem connections with DC injection with synchronous compensators and static reactive power compensation devices. The goal is to increase the reliability of the intersystem communication. In the event of short circuits on the AC line 6 simultaneously with its disconnection from the relay protection 20 followed by a three-phase automatic reclosing (AR) 21 through the protection and automation system 24 of the converter device 1, a signal is given for disconnecting and direct reclosing of the DC-current by acting on the control pulses of the bridge valves of the rectifier 16 and the inverter 17. For this, the rectifier pulses are transferred to the control zone of the inverter mode with the switching angles of 120-130 °, which provide ivaets decrease to zero current transformer, and then blocked feed control pulses to all the valves of the rectifier and the inverter. After a predetermined pause of time corresponding to the pause of the AC line AC 6, control pulses are again applied to all valves, moreover, to rectifier valves with switching angles of 120-130 ° and their subsequent transfer to the rectifying mode control zone, which ensures a smooth set current converter. 1 il.

Description

The invention relates to power engineering and can be used on AC intersystem connections with DC injection with synchronous compensators and static devices to compensate for reactive power.

The aim of the invention is to increase the reliability of the intersystem communication operation.

The drawing shows an interconnection scheme with DC injection.

Rectifying inverter substation

QVT contains a converter device 1, connected via transformers 2 and 3, respectively, with buses 4 and 5 adjoining and further along lines 6 and 7 of alternating current - with transmitting and receiving power systems 8 and 9. Filter compensating devices (PKU) 10 and I in tertiary transformer windings, synchronous compensators (CK) 12 and 13, and filter-blocking devices 14 and 15 on the adjoining tires provide reactive power compensation. The converter device 1 is formed by a two-bridge twelve-phase rectifier 16 and an inverter 17 connected via smoothing reactors 18 and 19.

Each AC line has a relay protection kit 20 connected to the voltage sensor and current line sensors in the converter station and the reclosing automation device 21 (shown only for line 6). In the event of violations on the line, its disconnection and three-phase automatic reclosing are performed by disconnecting the switch 22 from the protection set 20 and re-enabling them after a predetermined pause of time by the automatic control device 21. (At the same time, similar operations with switch 23 are performed for relay protection and automation in the power system 8).

The converter unit is equipped with a set of 24 protection and automation equipment (SZA). The disconnection followed by the automatic reclosing of the converter device is performed by the action of SZA on the control pulses of the bridges of the rectifier 16 and the inverter 17. For this, the rectifier's pulses are transferred to the control zone

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Neither inverter mode with turn-on angles 120-130 electr. grad., which ensures reduction to zero of the converter current, after which the supply of control pulses to all the rectifier and inverter valves is blocked. After a predetermined pause of time, control pulses are again applied.

South to all the valves, and to the rectifier valves, with switching angles of 120-130 electrons and their subsequent transfer to the control zone of the rectifying mode, which ensures a smooth 15 set of converter current.

When disconnected, followed by a three-phase auto-reclosing on lines 6 and 7, the transit of energy over the interconnection link is briefly stopped. At the same time, however, SC and PKU are able to support continuous operation of the converter device in the pause of the automatic reclosing line, the duration of which ke exceeds fractions of seconds. When the transit is disrupted by the rectifier, the energy stored in the flight masses of the CK 12 is taken and intensively braked. Conversely, the transit gap on the inverter side is accompanied by the acceleration of the SC 13. (If the SC is turned off, the artificial capacitive switching of the valves from the PKU is established, in which the rectified current is maintained by the combined action of the current regulators of the rectifier and inverter of the converter control system. the mode is dangerous due to its overvoltages. The line will be switched on again in both cases to the non-synchronous voltage of the SC, which is fraught with a loss of stability of the intersystem communication. The indicated reasons limit the possibilities of 45 changes of three-phase AR for AC lines.

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In the emergency process, when line 6 is violated, from the voltage sensors and line currents, a set of protection 20 is launched — remote, differential-phase high-frequency protection, etc. From the protection set 20, for certain types of violations, all three phases of the switch 22 are disconnected and the three-phase automation starts AR through device 21. At the same time, shutdown and start-up

The automatic reclosure of the converter device 1 through a set of 24 protection and automation equipment, made, for example, according to the connection shown by the dashed line in the drawing. This eliminates the process of energy conversion at the DCT, which is the cause of braking of the SC 12 when the connection with the transmitting power system 8 is disconnected (or of the SC 13 when the connection with the receiving power system 9 is broken with the three-phase ARF line 7). As a result, the SC continues to rotate almost synchronously with the power grid. The loss of its rotational frequency and the rotor angle of rotation is due only to friction losses and during the pause time the automatic reclosing is negligible.

If there are several conversion devices on the VPT shutdown and the start of the dependent ARC is performed simultaneously on all these devices, the duration of the best AR pause is selected the same for AC lines and the ACL or ARC at the VPT somewhat later with the delay necessary to establish the electromagnetic activation process AC lines.

Dependent automatic reclosing at main FPD is performed similarly, but with involvement of control equipment of both converter stations - rectifier and inverter.

The economic efficiency of the invention is determined by the reduction in the number of interconnection failures due to the possibility of using three-phase reclosing on AC lines. This is especially important for lines on the side of the receiving system, where a single-phase auto-reclosing is not practiced at all, as it causes disturbances in the switching of the valves and the inverter overturning.

Claims (1)

Invention Formula An intersystem communication control method consisting of alternating current lines connected by a direct current transmission (insert) containing synchronous compensators and static reactive power compensation devices, in which in alternate mode the alternating current lines are disconnected and automatically switched on. that, in order to increase the reliability of the intersystem communication, simultaneously with the disconnection and automatic re-activation of the AC lines, the disconnection and automatic switching ornoe transmission switch (paste) DC.