RU1802386C - Gear for connection of capacitor bank - Google Patents

Abstract

Field of use: in electric networks with switching capacitor banks using controlled valves. SUMMARY OF THE INVENTION: The presence of an auxiliary null-organ, power switch 1, three triggers and three control connection units leads to a decrease in switching noise and an increase in speed. This is due to the fact that the inclusion of power switches is carried out with equal voltages in the line and on the capacitor at the moments of arrival of pulses from the corresponding zero-organs and depends on the residual voltage on the capacitor. The capacitor bank incorporates discharge resistors that accelerate the discharge of the residual voltage after being disconnected from the mains. The control unit analyzes the voltage across the capacitor. During normal operation of power switches, the total voltage of the 3-phase network is zero. If one or more of the switches malfunctions, phase imbalance occurs. The control unit analyzes this voltage and, when the set level is exceeded, gives an alarm signal. 2 ill. ate with

Description

The invention relates to regulation of reactive power in electric networks with the connection and disconnection of capacitor banks using controlled valves.

I An object of the invention is to reduce switching noise and increase speed.

j In FIG. 1 given.principal diagram of the device; in FIG. 2 - graphs of the connection phase and subsequent disconnection of the capacitor bank.

 The device contains power switches 1, 2, 3, connected by their power inputs to the terminals of the electrical network, and power outputs to a capacitor bank 4, In addition, power switches 1, 2, 3 are connected by their control inputs to the outputs of blocks 5, 6, 7 of the connection power switches, respectively. whose inputs are connected to the outputs of triggers 8, 9, 10, respectively. The triggers 8, 9, 10 are connected by information inputs and reset inputs to the output of the connection control unit 11, the input of which is a signal to turn on the capacitor bank 4. The gate inputs of the triggers 8, 9, 10 are connected respectively to the outputs of the null organs 12, 13, 14 of the switched on parallel to the power switches 1, 2, 3.

The device operates as follows.

00

about

Yu

CA) 00

about

When the device is connected to the electric network and there is no voltage to turn on the capacitor bank 4, the ul-bodies 12, 13, 14 generate voltage impulses at the moments of equal voltage to the voltage switches 1, 2, 3. Voltage impulses from zero organs 12 , 13, 14 are fed to the strobe strokes of triggers 8, 9, 10, which, due to the lack of switching voltage at the information inputs of triggers 8, 9, 10, do not generate a signal to turn on the power switch blocks 5, 6, 7. The inputs power switches 1, 2, 3 does not receive voltage and any power switches 1,2,3 off. The capacitor bank 4 is de-energized.

When the control voltage is applied to connect the capacitor bank 4 to the shutdown control unit 11 (see Fig. 2, the time instant between ti and ta), the enable voltage is generated and applied to the information inputs of the triggers 8, 9, 10. When the first pulse comes from which or of a zero-organ 12,13, 14 (see Fig. 2 moment of time tz), the corresponding trigger 8, 9, 10 is transferred and provides voltage to the corresponding block 5, 6, 7 of connecting power switches from which a constant signal comes to the appropriate input, control. power comm Ator 1, 2, 3 and the power switch 1, 2, 3 is turned by connecting a capacitor to its corresponding phase. The next pulse will come at the moment the voltage in the adjacent phase is equal to the voltage in the already switched-on phase (see Fig. 2 torque tz) and the next switch will be connected in a similar way.

The third power switch 1, 2, 3 is connected when the voltage in the 3rd phase is compared with half the voltage between the other two already connected (Fig. 2 point in time TD The transition process between G3 and t4, when the current shape is distorted is 90 ° or 5 mS for industrial networks, that is, from the moment the signal arrives at c, the connection between ti and t2 until the connection is complete t4 goes from 120 ° to 180 ° ..:

Known devices make a connection for 360 °, i.e. The proposed device allows connecting a capacitor bank 2-3 times faster and reduces transients by 4 times.

Since the connection of the capacitor bank 4 occurs at the moment when the voltage in the phase is equal to zero (Fig. 2.1) f), then

the current in phase at these moments has a maximum value (Fig. 2.1f). But the magnitude of this current does not exceed the current amplitude in the steady state and does not cause overloads and interference in the electric network, similar to the already mentioned overloads in known devices,

To disconnect the capacitor bank 4 from the mains, the control voltage is turned off (Fig. 2, the instant between t and ta). As a result, the control unit 11 supplies the voltage to the reset input of flip-flops 8, 9, 10. The power switch blocks 5, 6, 7 are turned off and the switching voltage is not applied to the control inputs of the power switches 1, 2, 3.

When the phase current decreases to zero (Fig. 2, moment te), the corresponding power switch 1, 2, 3 is locked and 2 other power switches 1, 2,, 3 remain turned on. When the current decreases through the latter to zero (Fig. 2, moment tg), the other two power switches 1, 2, 3 are turned off. And the battery is completely disconnected from the mains. The voltage on the capacitor bank 4 (Fig. 2) after turning off the power switches 1, 2, 3 decreases exponentially

  1) f4 x,

where 1Gf4 is the residual voltage at time t9,

5 t is constant discharge time, and depends on the design features of the capacitor bank 4.

The connection control unit 11 analyzes the voltage 1) Φ4 on the capacitor bank 4 and, in the event of a malfunction of one of the power switches 1, 2, 3, makes a complete shutdown and gives an alarm signal. The use of the proposed device allows to increase performance

5 compensating installations by a factor of 2–3, to eliminate switching noise affecting the operation of electronic devices connected to this electrical network, which leads to a malfunction of normal operation

0 electronic equipment. In addition, the proposed device, due to its speed, makes it possible to create reactive power compensation devices capable of compensating for short-term rejects of reactive current, for example, at the moment of starting the electric motors.

Formula A device for connecting a capacitor bank, containing two power switches connected by inputs to the output to connect to the two phases of the three-network, and the outputs to the first and second terminals capacitor bank two zero-element connected inputs parallel to the power switches, the control voltage source, moreover, in order to reduce switching noise and increase speed, it is equipped with a third power switch , the third null organ, three triggers, and three power switch connection blocks, the third: a silt switch connected to the input

0

to the terminals for connection to the third phase of the network, and the output to the third terminal of the capacitor bank, the third zero-organ is connected by inputs parallel to the third power switch, the outputs of the three zero-organ are connected to the gate gate inputs / information and reset inputs of which are combined and connected to the source of the control signal, and the outputs of the triggers through the power switch connection blocks are connected to the control inputs of the respective power switches.