JPH0222404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention minimizes overvoltage and voltage distortion that occur when a reactive power supply device connected to the converter side circuit of a main transformer (converter transformer) is turned on in an AC/DC conversion system. In particular, the present invention relates to a power-on phase control device for a reactive power supply device that does not interfere with the operation of an inverter.

In an AC/DC conversion system, reactive power is required to operate the converter, and part of this can be supplied by an AC filter, but the remaining shortage can be supplied by an external reactive power supply device (hereinafter referred to as Var equipment). ) is used as a capacitor.

Figure 1 shows an example of such an AC/DC conversion system with a single wire connection, where 1 is an AC system, and 2 is a main transformer with one winding connected to the bus BUS connected to this AC system. , 3 is a converter connected to the other winding of this main transformer 2 via a reactor 4,
Reference numeral 6 denotes a Var equipment consisting of a capacitor C and a resistor R connected to an electric line connecting the other winding of the main transformer 2 and the reactor 4 via an AC disconnector 5. In this figure, if the converter 3 is operated as an inverse converter, the converter at the opposite end (not shown) of the DC circuit is operated as a forward converter, from which DC power is transmitted.

By the way, conventionally, when the Var equipment 6 is turned on while the converter is operating, it is done through the disconnector 5.
The operation is performed by a remote control device (not shown). In this case, since the breaker is generally operated for all three phases at once, if it is turned on at a voltage peak, it will be a severe case for AC voltage. Furthermore, in order to prevent this, the closing phase is controlled in a sequential manner, which would be impossible with mechanical operation of the disconnector.

If the AC voltage is turned on by an AC converter or disconnector without phase control, especially when the converter is operating as an inverse converter, the converter may malfunction, such as commutation failure due to distortion of the AC voltage. Additionally, the insulation of the converter may be damaged due to the generation of overvoltage.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to reduce overvoltage and voltage distortion that occur when a reactive power supply device connected to an electric line connecting a main transformer and a converter of an AC conversion system is turned on. It is an object of the present invention to provide a power-on phase control device for a reactive power supply device that can minimize the amount of noise caused by the inverter so as not to interfere with the operation of the inverter.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a single-wire AC/DC conversion system to which the present invention is applied, and the same parts as in FIG. 1 are given the same symbols, and different parts will be described here. That is, as shown in Fig. 2, the main transformer 2
A pair of thyristor switches SCR1, SCR2, 7 connected in series and antiparallel are connected to the Var equipment 6 connected to the electric circuit between the reactor 4 and the reactor 4, and disconnectors PS1, DS2 are provided on both sides In addition, a single-phase disconnector 5 is connected in parallel to the series circuit of these disconnectors DS1, a pair of thyristor switches SCR1, SCR2, 7, and disconnector DS2 provided in antiparallel.
5 are connected, and series circuits of capacitors C and resistors R corresponding to each of the three phases constituting the Var equipment are connected in Δ.

FIG. 3 shows the connection configuration of FIG. 2 in more detail as a three-phase circuit. In Fig. 3, L is a three-phase electric line consisting of R, S, and T phases connecting the main transformer 2 and converter 4 (all shown in Fig. 2), and DS1 and DS2 are the fixed side. The fixed side terminal of one of the disconnecting switches DS1 is connected to the R phase, the S phase, and the T phase of the three-phase line L, respectively, and the other Connect the fixed side terminal of disconnector DS2 to 3
Var to the S phase of the phase line L, to the T phase, to the R phase
The series circuits of each capacitor C and resistor R of the equipment 6 are connected through each separately. Also, both disconnectors
Fixed side terminals corresponding to DS1 and DS2,
, single-phase disconnectors CB1, CB2, CB
A pair of thyristors connected through 3 and 55, and whose movable side terminals are connected in antiparallel.
Connect to both ends of SCR1, SCR2, and 7. here,
In the disconnectors DS1 and DS2, when the thyristor switch 7 is not in use, the movable side terminal is connected to the fixed side terminal by a control device (not shown), and when the thyristor switch 7 is in use, the movable side terminal is connected to the fixed side terminal →→→→
The connections are automatically switched and connected in sequence at certain time intervals. In this case, the disconnectors DS1 and DS2 perform the same operation at the same time.

On the other hand, Figure 4 shows a pair of thyristor switches.
The gate control circuits of SCR1, SCR2, and SCR7 are shown using single wires, and the same symbols are attached to the configurations of the same circuit parts as in FIG. 2, and the explanation thereof will be omitted here. In Fig. 4, 20 is the main transformer 2
This is a transformer that detects the voltage between each of the three phases of the electric line connecting the bus and the bus, and its secondary output is applied to the rectangular wave generator 10. Further, a forward voltage of each valve of the converter 3 detected by a detector (not shown) is applied to the rectangular wave generator 10. This rectangular wave generator 10 detects the zero point of each AC voltage applied by a detector (not shown) that detects the forward voltage of each valve of the transformer 20 and converter 3, and generates a rectangular wave having a width of 180°. The positive wave of each AC voltage,
These are outputs corresponding to negative waves.
Rectangular waves corresponding to positive waves and negative waves of each AC voltage outputted from such a rectangular wave generator 10 are applied to the control circuit 30. As shown in FIG. 5, this control circuit 30 is synchronized with the changeover switches SWX, SWY, which are switched in response to stop and operation commands of the converter 3, and the positive and negative waves of the AC voltage input through the changeover switches SWX, SWY. Pulse generators 31-1 and 31-2 detect the rising edge of the rectangular wave and output pulses with a certain time width (for example, 1 ms). AND circuits AND1 and AND2, to which a condition signal of logical value "1" is applied when the movable side terminals of the disconnectors DS1 and DS2 are connected to the fixed side terminals. Pulse generators 32-1 and 32-2 which output pulses with a fixed time width (for example, 10 ms) to which the outputs of AND circuits AND1 and AND2 are added, and pulses output from the pulse generator 32-1 are input and the changeover switch is The square wave and pulse lock signal corresponding to the negative wave obtained through SWY are input to the negative terminal, respectively, and the pulse output from the pulse generator 32-2 is input to the AND circuit AND3 and the positive wave obtained through the changeover switch SWX. It consists of an AND circuit AND4 to which corresponding square wave and pulse lock signals are respectively applied to the negative terminals. Here, the above changeover switch SWX,
SWY is the square wave generator 1 when the converter 3 is stopped.
When the converter 3 is in operation, the rectangular waves corresponding to the positive and negative waves of the AC voltage output from the transformer 20 are input to the pulse generators 31-1 and 31-2. A switching operation is performed so that rectangular waves corresponding to positive waves and negative waves of the valve forward voltage detected by a detector (not shown) are input to the pulse generators 31-1 and 31-2. In addition, AND circuits AND3 and AND4 are changeover switches SWX and SWY.
The rectangular waves corresponding to the positive and negative waves of the AC voltage obtained through the AC voltage are interlocked to ensure that there are no opposing signals, and a pulse lock signal from the thyristor switch is added for further stability. Therefore, on condition that the interlock is released and the pulse lock signal is not applied, the pulse generator 3
2-1 and 32-2 are for sending output pulses.

The above AND circuit of such a control circuit 30
The outputs of AND3 and AND4 are applied to gate pulse circuits 8 and 8', and the gate pulses obtained as their operation outputs are applied to thyristor switches SCR1,
Add to the gates of SCR2 and 7 as an ignition signal.

On the other hand, reference numeral 9 denotes a short circuit breaker operating circuit to which a condition signal indicating that the thyristor switch 7 is firing is inputted by the control operation of the control circuit 30, and this short circuit breaker operating circuit 9 is shown in FIG. 6a. , b. That is, in Figure 6a, AND
5 is an AND circuit that outputs a logical value of "1" on the condition that the movable side terminals of the disconnectors DS1 and DS2 are connected to the fixed side terminals and the thyristor switch 7 is turned on; AND7 is an AND circuit that outputs a logic value of "1" on the condition that the movable terminal is connected to the fixed terminal and the thyristor switch 7 is turned on.
This is an AND circuit that outputs a logical value of "1" on the condition that the ignition is on. Further, IH1 to IH3 are inhibit circuits in which the AND circuits AND5 to AND6 are individually applied to one input terminal, and a protection signal is individually applied to the other negative input terminal, and these inhibit circuits IH1 to IH3 are connected to the corresponding single circuits. This command is used to give a closing command to the line breakers CB1 to CB3. In Figure 6b, OR1 is
It is an OR circuit whose input conditions are the signal output when Var equipment 6 is not in use and the signal output when protection is interlocked.
This gives an opening command to the

Next, the operation of the closing phase control device for the reactive power supply device configured as described above will be explained.
Now, when converter 3 is stopped, Var
Consider the case where equipment 6 is introduced. In this case, the transformer 2 is under no load, so if the phase difference between the voltages of the two electric lines connecting the main transformer 2 and the bus BUS and the main transformer 2 and the converter 3 can be ignored, the main transformer 2 The zero point of the line voltage of the converter side electric circuit can be detected by introducing voltage into the main transformer 2 from the bus side. Therefore, when the converter is stopped, the changeover switches SWX and SWY provided at the input stage of the control circuit 30 are switched to the converter stop side, so that the pulse generators 31-1 and 31-2 are connected to the converter. 180° different rectangular waves created by detecting the zero point of the AC voltage taken out from the device 20, that is, the zero point of the negative wave → positive wave and the zero point of the positive wave → negative wave, are applied. At this time, when the movable terminals of the disconnectors DS1 and DS2 are connected to the fixed terminals, the thyristor switch 7 is connected between the R and S phases of the electric circuit, and at the same time the AND conditions of the AND circuits AND1 and AND2 are set to It is established at the timing corresponding to the negative wave and the negative wave, and its output is sent to the pulse generators 32-1 and 32-2.
becomes a pulse with a constant time width, and the AND circuit
Joins AND3 and AND4. This AND circuit
In AND3 and AND4, pulses of the above-mentioned constant time width are applied to the gate pulse circuits 8 and 8' on the condition that the interlock has never occurred and that there is no pulse lock signal. As a result, the thyristor switch 7 is rendered conductive by being supplied with gate pulses from the gate pulse circuits 8, 8'. In this case, one of the thyristor switches in the antiparallel connection to which the forward voltage is applied is first energized, then the other thyristor switch is energized, and so on, and so on alternately every half wave. Therefore, R-S of the electric line L
Between the phases, the thyristor switch 7 is gated on immediately after the voltage zero point on the condition that the movable side terminals of the disconnectors DS1 and DS2 are connected to the fixed side terminals, so the Var equipment 6 is turned on at the minimum voltage. This means that the shock caused by charging can be reduced.

After that, the movable side terminals of the disconnectors DS1 and DS2 are connected to the fixed side terminals, and when the thyristor switch is ignited, the AND circuit shown in Fig. 6a is connected.
5, the AND condition is satisfied, and if there is no protection signal at this time, the inhibit condition for the inhibit circuit IH1 is not satisfied, and this inhibit circuit IH1
A closing command is issued to the single-phase disconnector CB1, and a pulse lock signal is sent under that condition, and when the AND condition of the AND circuits AND3 and AND4 shown in FIG. 5 is not satisfied, the thyristor switch 7 is turned off. Here, Var equipment 6 and disconnector CB1
This means that it is inserted between the R and S phases of the electrical circuit.

Next, when the disconnectors DS1 and DS2 operate and the movable side terminal is switched from the fixed side terminal to be connected,
The thyristor 7 is connected between the ST and T phases of the electric line L, and at the same time is connected to the disconnector DS1, which is input to the control circuit 30.
DS2 terminal conditions change. Then, control circuit 3
0 is the pulse generator 31-1, 31-2 as described above.
Detects the zero point of the input voltage of the relevant phase, creates a rectangular wave corresponding to a positive wave and a negative wave that differ by 180 degrees, and applies it to AND circuits AND1 and AND2. Therefore, the AND circuits AND1 and AND2 are connected to the disconnectors DS1,
When the AND condition with the terminal signal of DS2 is established, the thyristor switch 7 is turned on through the same operation process as described above, and the Var equipment 6 is connected to the S-T of the electric line L.
inserted between the phases.

Then, on the condition that the thyristor switch 7 is turned on, the AND circuit AND6 shown in FIG.
If the AND condition is satisfied and there is no output and protection signal, the inhibit circuit IH2 issues a phase input command to the single-phase disconnector CB2, and under that condition, a pulse lock signal is sent, and the thyristor is activated as described above. Switch 7 is turned off.

Here, the Var equipment 6 is inserted between the ST phase of the electric circuit L through the shield and the circuit breaker CB2.

Next, when the disconnectors DS1 and DS2 are operated and the movable terminal is switched from the fixed terminal to the fixed terminal, the thyristor switch 7 is connected between the TR phases of the electric circuit L and simultaneously input to the control circuit 30. The terminal conditions of disconnectors DS1 and DS2 change. In this case as well, through the same operating process as described above, the thyristor switch 7 is first turned on, and then, as shown in FIG.
The single-phase shiya breaker CB is operated by the shiya breaker operating circuit shown in
3 is applied between the TR phase of the electric circuit L.
Var equipment 6 is introduced.

In this way, when the Var equipment 6 is inserted into the electrical circuit L by the disconnector 55 for all three phases, the disconnector DS1,
From the movable side terminal of DS2 to the fixed side terminal,
A series of control operations is completed.

On the other hand, when the Var equipment 6 is disconnected from the electric circuit L, the insulation breaker operation circuit shown in FIG.
Issue a shear cut command to 1, CB2, and CB3, and cut off the three phases all at once, as in the past. Therefore, the thyristor switch 7 is in a standby state until the next turn on.

The above explanation is for the case where the converter 3 is stopped, but when the converter 3 is operating, the Var equipment 6
When switching on the switch SWX, SWY, the forward voltage of the valve is applied as an input voltage to the control circuit 30 that controls the gate of the thyristor switch 7, and the gate control of the thyristor switch 7 and the disconnectors DS1, DS2 are performed. By sequentially performing the switching, the Var equipment 6 can be turned on immediately after the voltage zero point of the corresponding phase. In this case, the zero point of the voltage of the electric line connecting the main transformer 2 and the converter 3 can be determined by detecting the terminal voltage of the bulb, here the forward voltage of the bulb, and inputting it to the control circuit 30.

According to this embodiment, when the Var equipment 6 is connected to the electric line L connecting the main transformer 2 and the converter 3 of the AC/DC conversion system, the Var equipment 6 is connected in series and in antiparallel to the Var equipment 6. A disconnector that connects a pair of thyristor switches 7 and sequentially switches and connects the thyristor switches 7 between each phase of a three-phase electric circuit L on both sides.
In addition to providing DS1 and DS2, these disconnectors DS1 and
A single-phase disconnector 55 is connected in parallel with the DS 2 and a pair of thyristor switches 7, and series circuits of capacitors and resistors corresponding to each of the three phases constituting the Var equipment 6 are connected in a △ manner. When the Var equipment 6 is inserted between each phase of the phase circuit, the thyristor switch 7 is controlled to conduct in synchronization with or near the zero point of the corresponding phase voltage of the three-phase circuit, and then the single-phase circuit breaker 55 of that phase is connected. , and the Var equipment 6 is sequentially connected between each phase of the three-phase electric line L.

Therefore, when a large-capacity Var equipment 6 is used, overvoltage and voltage distortion of the AC voltage at the time of application are minimized, and even when the converter is operated as an inverse converter, waveform distortion does not affect the control angle. Therefore, it is possible to prevent accidents such as commutation failure due to AC voltage distortion, and it is possible to turn on Var equipment without any problems while continuing operation.

In the above embodiment, the case where one group of Var equipment is introduced as shown in Fig. 3 was described, but if there are two or more groups of Var equipment, other groups'
Thyristor switch 7 is also used when installing Var equipment.
can be used in common.

Next, other embodiments of the present invention will be described.

In the above-mentioned embodiment, the thyristor switch 7 corresponding to one phase and the disconnectors DS1 and DS2 that switch and connect the thyristor switch 7 between each phase of the three-phase electric circuit are provided.
Var equipment was individually inserted between each phase of the three-phase circuit using three single-phase breakers CB1 to CB3, and this was configured as shown in Figures 7 and 8. can also be implemented. That is, as shown in FIG. 7, the Var equipment 6 corresponding to each of the three phases, in which a capacitor C and a resistor R are connected in series, is connected to each phase line of the three-phase electric circuit L, and the Connected in antiparallel, it becomes 1
Pair of thyristor switches 7-1, 7-2, 7-3
The configuration is such that they are connected in series. Further, as a gate control circuit, as shown in FIG.
2 and 30-3, and each of these control circuits 30-1 to 30-3 has a main transformer 2 and a bus line BUS sent out from a square wave generator 10 having the same function as that shown in FIG. Rectangular waves corresponding to positive waves and negative waves that are synchronized at or near the zero point of the AC voltage of the three-phase electric line connecting the valves and the forward voltage of the valve are input separately. The internal configuration of each of the control circuits 30-1 to 30-3 is approximately the same as that shown in FIG. 5, so only the different parts will be explained here, and the same parts as in FIG. 5 are given the same symbols. Therefore, the explanation will be omitted. In other words,
In Fig. 8, the difference from Fig. 5 is that the disconnector DS
1. Instead of inputting the switching terminal conditions of DS2, use the AND circuit to input the firing conditions of thyristor switch 7-1.
This is done by adding it to AND1 and AND2.

Therefore, in the above configuration, if the converter 3 is currently in operation, the changeover switch
SWX and SWY have been switched to positions opposite to those shown. As a result, each control circuit 30-1, 30-
2, 30-3 corresponds to the positive wave and negative wave of the forward voltage of the valve detected by a detector not shown.
A 180° different square wave is input, and the pulse generator 31
-1, 31-2, the pulse of a certain width that rises at the same time as the rise of the rectangular wave is the AND circuit AND1,
Added to AND2. At this time, AND circuit AND
If the ignition condition signal is input to 1 and AND2,
The AND condition is satisfied and the output is sent to the pulse generator 3.
2-1 and 32-2, where it becomes a constant width pulse and is applied to AND circuits AND3 and AND4. These AND circuits AND3 and AND4, when a pulse of a certain width is input, send out a pulse output on the condition that there is no interlock signal and pulse lock signal, and gate pulse circuits 8 and 4 shown in FIG.
Thyristor switches 7-1, 7-2,
Fire the gate 7-3. In this case, the firing order of the thyristor switches 7-1 to 7-3 is the zero point of the voltage between the RS phases of the three-phase electric line L connecting the main transformer 2 and the converter 3 (forward voltage between the RS phases of the valve). If the control circuit 30-1 is to operate from
Then, by operating the control circuits 30-2 and 30-3 in this order, the thyristor switches 7-2 and 7 are activated.
-3 is turned on, and the Var equipment 6 is sequentially applied between the RS phases, between the ST phases, and between the TR phases in about one and a half cycles of the AC voltage.

Therefore, the phase control device for the reactive power supply device having such a configuration also has the same characteristics as in the above embodiment.
Overvoltage and voltage distortion when turning on Var equipment are minimized, and even if the converter is being operated as an inverse converter, Var equipment can be turned on without any problems while continuing to operate.

In addition, the present invention can be implemented with various modifications without changing the gist thereof.

As described above, according to the present invention, in an AC/DC conversion system, the overvoltage and voltage distortion that occur when the reactive power supply device connected to the electrical line connecting the main transformer and the converter is turned on are minimized, and the inverse converter It is possible to provide a power-on phase control device for a reactive power supply device that can prevent the operation of the reactive power supply device from being hindered.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a conventional configuration in the case of introducing Var equipment into an AC/DC conversion system using a single connection, Fig. 2 is a system diagram similar to Fig. 1 showing an embodiment of the present invention,
3 is a detailed circuit configuration diagram showing the main part of FIG. 2 as a three-phase circuit, FIG. 4 is a circuit diagram showing the control system of the thyristor switch in the same embodiment, and FIG.
6a and 6b are block diagrams showing the inside of the control circuit shown in detail in detail. FIG. The system diagram, FIG. 8, is a configuration diagram of a control circuit used in the same embodiment. 1... AC system, 2... Main transformer, 3... Converter, 5
5...Single phase disconnector, 6...Reactive power supply device (Var
Equipment), DS1, DS2...Disconnector, 7, 7-1 to 7
-3... Thyristor switch, 8, 8'... Gate pulse circuit, 9... Shrink breaker operation circuit, 10... Square wave generator, 30... Gate control circuit, 31-1, 31
-2, 32-1, 32-2...pulse generator,
AND1~AND7...AND circuit, IH1~IH3...
Inhibit circuit, SWX, SWY...changeover switch.

Claims (1)

[Claims] 1. In an AC/DC conversion system in which a converter is connected to an AC system via a main transformer and the converter is operated as an inverse converter, the converter corresponds to each of the three phases of the converter side electrical circuit of the main transformer. a thyristor switch provided so that the reactive power supply device can be applied between the corresponding phases of the converter side line voltage and the converter side line voltage; When the forward voltage detection signal of the valve is input, the zero point of each AC voltage is detected and a 180° width rectangular wave is generated as a positive wave of AC voltage.
A rectangular wave generator that outputs each in response to a negative wave, and a switching operation in response to a stop or operation command of the converter, and corresponds to the AC system side line voltage that is output from the square wave generator when the converter stops. A changeover switch that takes in a rectangular wave that corresponds to the forward voltage of the valve of the converter during operation, and a rectangular wave that is synchronized with the positive wave and negative wave of the AC voltage input through this changeover switch. a pulse generator that detects a rising edge and outputs a pulse with a certain time width; and a pulse signal output from the pulse generator controls conduction of the thyristor switch to sequentially connect the reactive power supply device to the three phases of the electric circuit. 1. A power-on phase control device for a reactive power supply device, comprising a control means for synchronizing power-on between each phase.