JP2001238451A - Controller of power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakdown of a converter and peripheral devices by surely opening the AC side through throwing of BPP in a control protective device of multiple structure. SOLUTION: A controller of a power converter controls an externally excited power converter 200 of three-phase bridge formed of a semiconductor and the other switching element with a control protective devices 100, 300 of the multiple structure. When this controller is connected to a certain AC input terminal, a pair of upper and lower arms are set conductive simultaneously and a bypass pair that is short-circuited for DC side and is opened for AC side is formed, and a pair of upper and lower arms of a desired phase of 3-phase bridge determined previously as the bypass pair throwing phase are controlled for conductive and non-conductive conduction with a phase control circuit 110.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a power conversion device that controls a separately-excited conversion device such as a thyristor conversion device used for DC power transmission or the like by a multiplexed control protection device.

[0002]

2. Description of the Related Art In the case of power transmission such as direct current transmission, there are many cases where a control protection device is multiplexed and a separately-excited power converter is controlled in order to improve the reliability of the system. Therefore, hereinafter, an example in which the control protection devices are multiplexed will be described.

FIG. 5 is a block diagram of a control device of a multiplexed separately-excited converter.

[0004] Another example of a converter control and protection device 100 is a protection interlocking circuit 101 for outputting a bypass pair (hereinafter abbreviated as BPP) input command 103 for operating a gate signal in the event of a converter failure, and a DC or DC voltage. A control circuit 102 which is constituted by a circuit for controlling the phase constant and outputs a phase control signal 104, and a phase control circuit 110 which generates a gate signal based on the BPP input command from the protection interlocking circuit 101 and the phase control signal 104 from the control circuit 102 It is composed of

The phase control circuit 110 generates a gate pulse according to the phase control signal 104, and outputs a BPP input phase
BPP input phase selection circuit 113 for selecting 4;
Switching output corresponding to each phase, BPP input command 10
3, the gate pulse switching circuit 11 locks the output of the gate pulse generation circuit 111 when the BPP phase is turned on.
2. Normally, the gate pulse selected by the gate pulse switching circuit 112 is output.
When locked by P input command 103, BPP
BPP input phase 1 selected by input phase selection circuit 113
A gate pulse output circuit 115 that outputs a gate pulse supplied to 14 is provided.

On the other hand, another system separately excited type converter control and protection device 30
0 has the same configuration as that of the separately-excited converter control device 100, outputs the output signal 20 of the other-system separately-excited converter control and protection device to the OR circuit 11, and outputs the gate pulse output signal 10 synthesized by the OR circuit 11. Output to separately-excited power converter 200.

FIG. 6 shows details of the separately-excited power converter. Circuits that perform the same functions as those in FIG. 5 are denoted by the same reference numerals.

In FIG. 6, a separately-excited power converter 200
Is composed of a three-phase bridge, and the input voltages of the three-phase AC are A-phase, B-phase, and C-phase, respectively, and the AC input voltage delayed by 120 degrees from the A-phase is delayed by 120 degrees from the B-phase and B-phase. The applied AC input voltage is a C phase.

The converters constituting the three-phase bridge include a converter in which the anode of the switching element is connected to the AC input phase A phase, a U-phase converter, and a converter in which the cathode is connected to X-phase.
The converter in which the anode of the switching element is connected to the AC input phase B is the V phase, the converter in which the cathode is connected is the Y phase, and the anode of the switching element is connected to the AC input phase C. The converter that is connected is the W phase, and the converter to which the cathode is connected is the Z phase.

The separately-excited power converter 200 comprises a three-phase bridge using semiconductors and other switching elements. During normal operation, the control and protection devices of the multiplex system combine with the separately-excited power converter 200. It is controlled by the switching signal 10 to each converter that is output after being output, and in the event of a failure of the converter, on any phase to which the AC input terminal is connected,
A BPP is formed in which the lower pair of converters are caused to flow simultaneously to make a short circuit state when viewed from the DC side and an open state when viewed from the AC side.

In this case, in order to change from the normal commutation state to the BPP state, a pair of upper and lower phases is selected by the phase that is flowing in advance to form the BPP.

[0012] Conventionally, as a method of selecting a BPP input phase at the time of input to a BPP, Japanese Patent Application Laid-Open No. 4-150776 (published May 25, 1992) discloses a "bypass pair control circuit of a thyristor bridge". And a known technique.

[0013]

However, when a BPP is formed by a conventional method in a control protection apparatus configured by multiplexing, the following events may occur.

For example, in the case of a control device having a double system, it is assumed that the output timings of the gate pulses do not completely match due to a phase detection error of each control protection device. Specifically, there may be a state in which one of the dual systems outputs the Z-phase gate pulse while the other system does not output the Z-phase gate pulse.

At this time, the system outputting the Z phase is U-phase.
The system that determines that the Z phase is in the conducting state and inputs the X phase, and the system that does not output the Z phase determines that the YU phase is in the conducting state and inputs the V phase.

Therefore, the first series of control protection devices is as follows:
The UX phase is selected as the BPP phase, and the second series of control protection devices selects the VY phase as the BPP phase. That is, U-
X-phase and V-Y-phase two sets of converters
Since the lower pair of converters are in a conducting state and a single-phase rectifier is configured, the AC side does not open.

In such a state, the AC current continues to flow, and by forming the BPP, the AC system and the DC system cannot be separated from each other. Etc. may occur. As a result, there is a concern that accidents may increase, it may take a long time to restore the DC transmission system, and it may not be possible to achieve the originally required reliability during operation.

The present invention has been made in view of the above circumstances, and in a multiplexed control and protection device, the AC side is reliably opened by turning on the BPP to prevent damage to the converter and peripheral devices. It is an object of the present invention to provide a control device for a power conversion device with high reliability.

[0019]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a control device for a power conversion device using the following means.

The invention corresponding to claim 1 is a control device of a power conversion device for controlling a power conversion device of a three-phase bridge composed of semiconductors and other switching elements by a multiplexed control protection device. When a bypass pair is connected to one AC input and the lower pair of arms are allowed to flow simultaneously and short-circuited when viewed from the DC side, and opened when viewed from the AC side, it is determined in advance as the bypass pair input phase. And a pair of upper and lower arms of any one of the three-phase bridges.

According to a second aspect of the present invention, in the power converter control apparatus according to the first aspect of the present invention, the bypass pair input phase is sequentially changed on a rotating basis every time the converter is started or restarted. It is like that.

According to a third aspect of the present invention, in the control device for a power conversion device according to the first aspect of the present invention, the bypass pair input phase counts the number of times of the bypass pair input command and increments by 3 every predetermined count. This is to be selected for the other phase of the phase bridge.

Therefore, in the control device of the power converter having such a configuration, even if the multiplexed control protection device outputs the gate pulse of the BPP phase, it is output from each control protection device. Since the BPP input phases are the same, selection of a plurality of BPP input phases can be avoided, and the DC side is reliably short-circuited and the AC side is opened.
PP can be formed.

[0024]

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

FIG. 1 is a circuit diagram showing a first embodiment of a control device for a separately-excited power converter according to the present invention. Circuits having the same functions as those in FIG. 5 are denoted by the same reference numerals.

In FIG. 1, another example of a converter control and protection device 100 operates a gate signal in the event of an AC system accident.
A protection interlocking circuit 101 that outputs a PP input command 103, a control circuit 102 configured to control a DC current or a DC voltage to be constant, outputs a phase control signal 104, and a BPP input command from the protection interlocking circuit 101 and a control circuit A phase control circuit 110 generates a gate signal with the phase control signal 104 from the controller 102.

The phase control circuit 110 has a predetermined three-phase control based on a gate pulse generation circuit 111 for generating a gate pulse in accordance with the phase control signal 104 and a BPP input command 103 issued from the protection interlocking circuit 101 in the event of a converter failure. B that generates a gate pulse by using a pair of upper and lower arms of any one of the bridges as a fixed BPP input phase
PP input circuit 120, normally gate pulse generation circuit 11
A gate pulse switching circuit 112 which switches the gate pulse generated from 1 in correspondence with each of the three phases and locks the output of the gate pulse generation circuit 111 when the BPP is input according to the BPP input command 103. A gate that outputs a gate pulse selected by the pulse switching circuit 112 and outputs a gate pulse given from the BPP input circuit 120 to the fixed BPP input phase 114 when the gate pulse switching circuit 112 is locked by the BPP input command 103. It is composed of a pulse output circuit 115.

On the other hand, another system separately-excited converter control protection device 30
0 has the same configuration as that of the separately-excited converter control device 100, outputs the output signal 20 of the other-system separately-excited converter control and protection device to the OR circuit 11, and outputs the gate pulse output signal 10 synthesized by the OR circuit 11. Output to separately-excited power converter 200.

In FIG. 1, the fixed BPP input from the BPP input circuit 120 to the gate pulse output circuit 115
The input phase is, for example, the UX phase.

Next, the operation of the control apparatus of the separately-excited power converter constructed as described above will be described with reference to FIG. 6. Here, the energization timing of the U and X phases when the UX phase is the BPP input phase and the like will be described. 2 to FIG. 4 will be described.

FIG. 2 shows, as pattern (1), a phenomenon when the U and X phase BPPs are turned on while the U phase is energized and the X phase forward voltage is applied.

In the pattern (1) shown in FIG.
Since the phases are already energized and a forward voltage is applied to the X phase, when a pulse is given, the X phase turns on.

At this time, due to the voltage difference between the X phase and the Y phase, Y
→ X commutation occurs, the Y phase is turned off, the X phase is energized, and the BPP is completed.

FIG. 3 is a pattern (2) showing the phenomenon when the U and X phase BPPs are turned on during the application of the U-phase forward voltage and the application of the X-phase reverse voltage.

In the pattern (2) shown in FIG.
At the time of the PP input command, a forward voltage is applied to the U phase, and a reverse voltage is applied to the X phase.

In this state, a period occurs in which the U, X, W, and Y phases are simultaneously turned on. Since this period is equivalent to a three-phase short-circuit state, the voltages of the DC outputs P and N become zero. .

Since the voltage difference between the W (C) phase and the U (A) phase is larger than the voltage difference between the X phase and the Y phase, W → U
Commutation ends first.

At this time, the voltage of the DC output P becomes equal to the A-phase voltage. Further, the voltage of N becomes an average value of the A-phase voltage and the B-phase voltage since the commutation of X → Y continues.

Eventually, only the U and X phases are energized, and the BPP is completed. However, when the U and X phases are turned on, the outflow of energy from the DC circuit to the AC circuit has been completed.

As described above, when the BPP input command is issued, the U phase is turned on, and the commutation of W → U occurs. At this time, the AK voltage of the X phase jumps in the forward voltage direction as shown by the broken line. Turn on.

FIG. 4 shows, as pattern (3), the phenomenon when the U-phase and X-phase BPP are turned on during the application of the U-phase forward voltage and the application of the X-phase forward voltage.

In the pattern (3) shown in FIG.
A forward voltage is applied to the phase, and a forward voltage is applied to the X phase.

In this state, a period occurs in which the U, X, W, and Y phases are simultaneously turned on. Since this period is equivalent to a three-phase short-circuit state, the voltages of the DC outputs P and N become zero. .

Since the voltage difference between the W (C) phase and the U (A) phase is larger than the voltage difference between the X phase and the Y phase, W → U
Commutation ends first.

At this time, the voltage of the DC output P becomes equal to the A-phase voltage. Further, the voltage of N becomes an average value of the A-phase voltage and the B-phase voltage since the commutation of X → Y continues.

Eventually, only the U and X phases are energized, and the BPP is completed. However, when the U and X phases are turned on, the outflow of energy from the DC circuit to the AC circuit has been completed.

As described above, when the BPP injection command is issued, the U phase, X
Since a forward voltage is applied to both phases, when a pulse is applied, the U phase and the X phase are turned on.

As described above, in the present embodiment, by setting a pair of upper and lower arms of a predetermined three-phase bridge as a fixed BPP input phase,
The BPP is formed quickly as in the method of selecting the PP input phase based on the energized phase, and the DC side can be reliably short-circuited and the AC side can be opened in the multiplexed control protection device.

In the above description, the configuration in which the BPP phase is fixed to an arbitrary one phase has been described. However, for example, the converter of the lower pair of arms corresponding to each phase of the three-phase bridge is activated or restarted. The BPP phase to be selected may be changed on a rotating basis each time it is started. With such a configuration, in addition to the effects described above, the stress of the thyristor valve can be dispersed.

Also, the number of BPP commands is counted, and
The same effect as described above can be obtained by selecting a pair of arms above and below one phase of the three-phase bridge as the BPP phase for each fixed count.

Further, it goes without saying that the same effect as described above can be obtained even if the operator manually selects the BPP phase to be selected.

[0052]

As described above, according to the present invention, even if the timing of the gate pulse is not completely synchronized due to an error between the control protection devices multiplexed by power transmission such as DC power transmission, Any one of the predetermined three-phase bridges
The upper and lower pair of arms are configured as a fixed BPP input phase, and the BPP input phases from each device are all the same, so that a single-phase rectifier is not formed when the BPP is input. Since the AC system and the DC system can be reliably separated from each other, damage to the converter and peripheral devices can be prevented.

Therefore, a BPP can be reliably formed, and an accident can be surely eliminated by protection interlocking or the like for the purpose of eliminating the accident. Therefore, it is possible to provide a control device for a power conversion device with high operation reliability.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of a control device for a power conversion device according to the present invention.

FIG. 2 is a diagram showing a phenomenon when a U-phase and an X-phase BPP are turned on during application of a U-phase current and application of an X-phase forward voltage in the embodiment.

FIG. 3 is a diagram illustrating a state where a -X voltage is applied during application of a U-phase forward voltage in the embodiment.
The figure which shows the phenomenon at the time of turning on the U and X phase BPP during the application of the phase reverse voltage.

FIG. 4 is a diagram showing a state in which -X during application of a U-phase forward voltage
The figure which shows the phenomenon at the time of application of U and X phase BPP during application of a phase sequence voltage.

FIG. 5 is a circuit configuration diagram showing a control device of a conventional power converter.

FIG. 6 is a circuit diagram showing a typical example of a three-phase bridge configuration of the power converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Gate pulse output signal, 11 ... OR circuit, 20 ... Output signal of other system separately-excited converter control protection device, 100 ... Self-excited converter control protection device, 101 ... Protection interlocking circuit, 102 ... Control circuit, 103 ... BPP input command, 104: phase control signal, 110: phase control circuit, 111: gate pulse generation circuit, 112: gate pulse switching circuit, 113: BPP input phase selection circuit, 114: BPP input phase, 115: gate pulse output circuit , 200: separately-excited power converter, 300: other-system separately-excited converter control and protection device.

Claims (3)

[Claims] 1. A control device of a power conversion device for controlling a power conversion device of a three-phase bridge composed of semiconductors and other switching elements by a multiplexed control protection device, wherein the control device is connected to a certain AC input terminal. When forming a bypass pair in which a pair of upper and lower arms are caused to flow simultaneously and a short-circuit state is viewed from the DC side and an open state is viewed from the AC side, the three phases previously determined as bypass-pair input phases are formed. A control device for a power conversion device, wherein a flow of a pair of upper and lower arms of any one phase of a bridge is controlled. 2. The power converter according to claim 1, wherein the bypass pair input phase is sequentially changed on a rotating basis each time the converter is started or restarted. Equipment control device. 3. The control device for a power conversion device according to claim 1, wherein the bypass pair input phase counts the number of bypass pair input commands and selects another phase of the three-phase bridge for each predetermined count. A control device for a power conversion device, characterized in that: