JP3321297B2 - Control device for voltage source self-excited converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a self-excited reactive power compensator, a self-excited DC power transmitting device, a fuel cell system, and the like, and includes a self-turn-off device (hereinafter abbreviated as GTO) such as a gate turn-off thyristor. A voltage that has a DC voltage source such as a capacitor, a battery, and a rectifier on the DC terminal side of the bridge-connected converter, and a transformer that converts an AC power system voltage to a desired value on the AC terminal side of the power converter. More particularly, the present invention relates to a control device for a voltage-type self-excited converter, which has an improved control circuit for suppressing the magnetization of a transformer installed between the converter and a power system.

[0002]

2. Description of the Related Art Conventionally, a transformer for a converter is provided between an AC power system and a voltage-type self-excited converter so that the AC system voltage becomes a desired value. In order to prevent this, there is a control device for a voltage-type self-excited converter to which a demagnetization suppression control circuit that suppresses demagnetization by a DC component of the output current of the converter is used.

FIG. 11 is a diagram for explaining this.
This is configured as follows. That is, a power system 1, an instrument transformer 2 for measuring system voltage, a current detector 3 for measuring an output current to the power system 1, and a transformer 4 for a converter.
Consists of In the transformer 4 for the converter, the windings on the system side are connected in series, and the windings on the converter side are independently connected to the self-excited converters 6A to 6D.

The current detectors 5A to 5D are respectively GTO
(Gate turn-off thyristors) to detect output currents of the self-excited converters 6A to 6D. Converter 6A ~
A DC voltage detector 7 and DC voltage sources 8A and 8B such as capacitors are connected to the DC terminal side of 6D. The power detector 9 calculates, from the system voltage detected by the instrument transformer 2 and the output current to the power system 1 detected by the current detector 3,
The active power and the reactive power output to the power system 1 are detected.
The power control circuit 10 receives the power detected by the power detector 9 and the DC voltage detected by the DC voltage detector 7 as inputs and controls the active power and the reactive power of the converters 6A to 6D. The demagnetization suppression control circuit 12 corrects the output voltage command value output from the power control circuit 10 with the output of the DC component detection circuit 11 that detects the DC component of the converter output current. The pulse width modulation circuit (PWM circuit) 13 is a demagnetization suppression control circuit 1
On / off of the self-extinguishing element is determined based on the output voltage command value corrected in step 2. A pulse amplifier (PA) 14 amplifies the pulse obtained from the pulse width modulation circuit 13 and supplies the amplified pulse to each self-extinguishing element.

In FIG. 11, a power control circuit 1 is normally used.
0 and the pulse width modulation circuit 13 are self-excited converters 6A to 6A.
The GTO firing pattern is determined so that the DC voltage is not included in the output voltage of D. However, the actual output voltage is GTO
The waveform becomes a waveform including a direct current component due to the characteristics of the signal and the variation of the transmission time of the gate signal. If the output voltages of the self-excited converters 6A to 6D include a DC component, the voltage-time product applied to the converter transformer 4 per cycle does not become zero, so that the iron core of the transformer 4 is gradually biased. The self-excited converters 6A to 6D stop protection due to magnetizing, the exciting current increases, and an overcurrent occurs. In the worst case, the self-extinguishing converters 6A to 6D may be damaged.

In the conventional circuit shown in FIG. 11, self-excited converters 6A to 6D are controlled by current detectors 5A to 5D in order to prevent demagnetization.
The output current of D is detected, the direct current component of the exciting current generated in the process of demagnetization is detected by the direct current component detection circuit 11, and the correction is performed by the depolarization suppression control circuit 12 based on the direct current component. The amount was added to the output voltage command value from the power control circuit 10 to perform PWM control, and the output voltages of the self-excited converters 6A to 6D were adjusted so as to cancel out the magnetic bias.

[0007]

In FIG. 11, the voltage of the power system 1 is usually a sinusoidal AC voltage. FIG. 12 shows the relationship between the output voltage command value at that time, that is, the value obtained from the carrier wave and the modulation wave of the PWM waveform, and the phase voltage waveform of the converter output. The converter output phase voltage does not include a DC voltage component except for a characteristic of the GTO, a variation in transmission time of the gate signal, and the like.

However, in a substation in which a large-capacity reactive power compensator or a self-excited converter applied to DC transmission or the like is installed, a large-capacity power capacitor is turned on, and an adjacent large-capacity transformer is turned on. At times, the system voltage may be greatly distorted or a DC component may be generated in the system voltage.

When the system voltage is distorted, the power control circuit distorts the output voltage command value of the self-excited converter in the same manner as the system voltage in order to prevent an overcurrent due to the distortion. FIG. 13 shows a waveform when pulse width modulation is performed based on the output voltage command value distorted in such a manner.

FIG. 13 is a waveform when the amplitude of the sine wave of the fundamental frequency is 66% of the amplitude of the carrier wave, and the second harmonic contains 25% of the amplitude of the sine wave and has a phase difference of 90 degrees. is there.
The converter output phase voltage in FIG. 13 has a negative-side voltage increase in a shaded portion as compared with FIG.
The voltage on the positive side increases in the vertical line portion, and when subtracted, a positive DC voltage is generated. That is, if the modulated wave is distorted, even if the DC component is not included in the one-cycle integral value of the modulated wave, the converter output voltage after the pulse width modulation includes the DC component.

[0011] For example, when the second harmonic of 4% is included, its value reaches 5% of the peak value of the rated voltage-time integration of the transformer as a DC component per cycle. Assuming that the rated magnetic flux density during normal operation of the transformer is 2/3 of the saturation magnetic flux density, the value is such that the transformer is saturated in about 10 cycles.

Such a magnetic bias due to a DC voltage component having a large value compared to that during the normal operation cannot be made by the correction based on the DC component of the converter DC winding current shown in FIG. There was a problem that the system stopped.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problem. In a voltage-type self-excited converter, the system voltage is distorted when an adjacent large-capacity transformer is turned on or a large-capacity capacitor is turned on. Even in such a case, it is an object of the present invention to provide a control device for a voltage-type self-excited converter that can be operated stably without saturating the converter transformer and causing overcurrent.

[0014]

In order to achieve the above object, a first aspect of the present invention is a power converter for connecting a self-extinguishing element to a bridge and converting DC to AC or AC to DC. And a transformer having an AC terminal side of the power converter and converting an AC power system voltage to a desired value.
In a voltage source self-excited converter comprising a DC voltage source provided on a DC terminal side of the power converter, an integrating means for integrating an AC output voltage of the power converter in a power supply basic cycle, and an output of the integrating means. And a correcting means for correcting the voltage command value of the AC output of the power converter.

According to another aspect of the present invention, there is provided a power converter for converting a direct current to an alternating current or an alternating current to a direct current by bridging a self-extinguishing element. A voltage-source self-excited converter comprising a transformer having an AC terminal side of the transformer and converting an AC power system voltage to a desired value, and a DC voltage source having a DC terminal side of the power converter. Means for integrating the AC output voltage of the heater in a half cycle of the power supply basic cycle, addition means for calculating the sum of the output of the integration means and the output of the previous integration means, and the output of the addition means. And a correcting means for correcting the voltage command value of the AC output of the power converter.

According to a third aspect of the present invention, there is provided a control device for a voltage-type self-excited converter according to the first or second aspect, wherein the AC output voltage is converted to a DC voltage detection value. And a control device for the voltage-type self-excited converter, which is calculated from a firing command of the self-extinguishing element.

According to a fourth aspect of the present invention, there is provided a control apparatus for a voltage-type self-excited converter according to the first or second aspect, wherein the integration means for the AC output voltage includes: Voltage frequency conversion means for converting the detected value of the voltage into a frequency, and in synchronization with the output of the voltage frequency conversion means, counts up while the high-voltage self-extinguishing element is on, and the low-voltage self-extinguishing element turns on. And a counter that counts down during the current period.

According to a fifth aspect of the present invention, there is provided a power converter for converting a direct current to an alternating current or an alternating current to a direct current by bridging a self-extinguishing element. A voltage-source self-excited converter comprising a transformer having an AC terminal side of the transformer and converting an AC power system voltage to a desired value, and a DC voltage source having a DC terminal side of the power converter. Means for integrating the AC output voltage of the unit at the basic cycle of the power supply, level detecting means for detecting that the output of the integrating means has exceeded a certain value, and when a detection signal is output from the level detecting means. ,
And a correcting unit for correcting an AC output voltage command value of the power converter based on an output of the integrating unit.

According to a sixth aspect of the present invention, there is provided a power converter for converting a direct current to an alternating current or an alternating current to a direct current by bridging a self-extinguishing element. A voltage-source self-excited converter comprising a transformer having an AC terminal side of the transformer and converting an AC power system voltage to a desired value, and a DC voltage source having a DC terminal side of the power converter. Means for integrating the AC output voltage of the heat exchanger in a half cycle of the power supply basic cycle, addition means for calculating the sum of the output of the integration means and the output of the previous integration means, and wherein the output of the addition means is constant. Level detecting means for detecting that the value has been exceeded, and when a detection signal is output from the level detecting means, an AC output voltage command value of the power converter based on the output of the adding means is corrected. Correction means; A control device for Bei the voltage type self-commutated converter.

[0020]

According to the first aspect of the present invention, the AC output voltage of the power converter is integrated by the integrating means in the basic period of the power supply, and the DC voltage component included in the converter output voltage detected by the integrating means is canceled. By correcting the converter output voltage command value in the next cycle as described above, the system voltage may be distorted due to the input of the adjacent large-capacity transformer or the input of the large-capacity capacitor, and the converter output may include a DC voltage component. In addition, it is possible to provide a control device for a voltage-type self-excited converter that can suppress the direct current component at high speed and operate stably without causing a magnetic overcurrent.

According to the second aspect of the present invention, the AC output voltage of the power converter is integrated by the integrating means in a half cycle of the power supply basic cycle, and the sum of the integrated output and the previous integrated output is calculated. Thus, the DC voltage component included in the immediately preceding cycle can be detected every half cycle. Furthermore, if the converter output voltage command value of the next half cycle is corrected so as to cancel the DC voltage component, the DC component can be canceled at a higher speed. A control device for a voltage-type self-excited converter that can be provided can be provided. Also, by performing integration every half cycle and calculating the DC voltage component for the immediately preceding cycle by calculation, the DC voltage component is updated every half cycle, and the output voltage command value can also be corrected every half cycle. Dead time is reduced, and faster control is possible.

According to a third aspect of the present invention, in the control device according to the first or second aspect, the AC output voltage is output as a positive DC voltage during a period in which the high voltage side element is ignited. During the firing of the low-voltage side element, the DC voltage is output from the negative polarity, so that it is calculated and detected, thereby eliminating the need for a measuring device for the terminal voltage of the transformer-side winding of the transformer. An economical self-commutated converter controller can be provided.

According to the fourth aspect of the present invention, since the integrating means is constituted by a digital circuit, it becomes unnecessary to measure the terminal voltage of the transformer-side winding of the transformer, which is economical. In addition, it is possible to reduce a DC component detection error due to an offset or a drift of the integrating means, and to provide a more reliable self-excited converter control device.

According to the fifth aspect of the present invention, when the value of the DC voltage component output from the integrating means exceeds a certain value, the AC output voltage of the power converter based on the output of the integrating means is obtained. Since the command value is corrected, unnecessary correction due to minute DC components due to errors in the integration means, etc. is not performed, and the system voltage is distorted and converted when the adjacent large-capacity transformer is turned on or the large-capacity capacitor is turned on. When a DC voltage component is included in the output of the transformer, it is possible to provide a highly reliable self-excited converter control device that performs correction and suppresses the magnetic bias of the transformer.

Further, according to the present invention, when it is detected that the output of the adding means for calculating the sum of the output of the integrating means and the previous output of the integrating means exceeds a predetermined value, the adding means is provided. Since the AC output voltage command value of the power converter is corrected based on the output of the power converter, unnecessary correction by a minute DC component due to an error in the integration means etc. is not performed. A reliable and high-speed self-commutated converter control device that corrects when the DC voltage component is included in the converter output and suppresses the transformer demagnetization when the system voltage is distorted due to the insertion of the large capacity capacitor. Can be provided.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> One embodiment of the present invention (an embodiment of the invention corresponding to claim 1)
Will be described with reference to FIG. In FIG. 1, the same elements as those in FIG. 11 described above are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, voltage detectors 15A to 15D
Measures the converter output voltage. The synchronization detector 16 is composed of, for example, a phase locked loop circuit (PLL), receives the system voltage measured by the instrument transformer 2, and generates a pulse synchronized with the system voltage. The integrator 17 is the AC voltage detector 1
The converter output voltage detected by 5D is integrated for each basic period of the system voltage detected by the synchronous detector 16. Integrator 1
For 7 simplicity, only the integrator output voltage of the converter 6D is not shown, performs the correction of the respective output voltage is provided as well to the transducer 6A-6C.

FIG. 2 is a diagram showing in detail one converter in FIG. 1, and FIG. 2 already described in FIG.
1, the same elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 2, the converter is a self-extinguishing element such as a GTO.
18A to 18F, diodes 19A to 19F respectively connected in anti-parallel thereto, and DC voltage sources 8A and 8B such as capacitors.

[0028] The delay circuit 20 is the integrator 17A~1
7C values from the held hold circuit (holding circuit) 21A to 21C of a circuit for to perform a reset of the integrator 17A-17C. The delay time of the delay circuit 20 needs to be a time sufficient for the holding circuits 21A to 21C to hold and as short as possible.

<Operation and Effect of First Embodiment> The operation and effect of the first embodiment will be described with reference to FIGS. If the system voltage is not distorted and has a sinusoidal waveform, the converter output phase voltage has the same positive and negative voltages as already shown in FIG. If the output voltages are equal in positive and negative, the holding circuit 2 is switched every system basic period detected by the synchronization detector 16 in FIG.
The outputs of the integrators 17A to 17C held by 1A to 21C become zero.

However, when the system voltage is greatly distorted, for example, when a large-capacity power capacitor is turned on or when an adjacent large-capacity transformer is turned on, the converter output phase voltage has a waveform including a DC component as described with reference to FIG. Becomes Then, the integrator 17A
The holding circuits 21A to 21C that hold the outputs of C to 17C every system basic cycle have a difference between the integral value of the positive side voltage and the integral value of the negative side voltage, that is, the area of the hatched portion in FIG. The result of subtracting the area is output. The demagnetization suppression control circuit 12 determines a correction amount so that the DC component for one cycle of the power supply basic cycle held in the holding circuits 21A to 21C is canceled in the next cycle, and the output voltage command from the power control circuit 10 is determined. If the value is corrected, the DC output component of the converter is not accumulated, so that the magnetic bias can be prevented.

According to the first embodiment described above, the integrators 17A to 17C for integrating the AC output voltage of the voltage source self-excited converter in the basic period of the power supply are provided, and the conversion detected by the integrators 17A to 17C is provided. By correcting the converter output voltage command value in the next cycle so as to cancel the DC voltage component included in the output voltage of the transformer, the system voltage is distorted when the adjacent large-capacity transformer is turned on or the large-capacity capacitor is turned on. Even when a DC voltage component is included in the output of the converter, it is possible to provide a control device for a voltage-type self-excited converter that can suppress the DC component at high speed and can operate stably without causing a magnetic overcurrent.

<Second Embodiment> FIG. 3 shows a second embodiment of the present invention (an embodiment of the present invention corresponding to claim 2).
The same elements as those already described in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. FIG. 3 is a diagram showing one self-excited converter in the system of FIG. 1 as in FIGS. 3 and 2, and similar circuits are added to the remaining three converters.

In FIG. 3, synchronization signals (output signals) 51 and 52 from the synchronization detector 16 are signals which are output every basic period of the power supply and are 180 ° out of phase with each other. The OR circuit 22 calculates the logical sum of the synchronization signals 51 and 52 from the synchronization detector 16. Among the holding circuits 21A to 21F, the holding circuits 21A, 21C, and 21E hold the values by the synchronization signal 51 of the synchronization detector 16, and hold the values by the holding circuits 21B, 21D, and 21E.
F holds the value of the synchronization signal 52 which is 180 degrees out of phase with the synchronization signal 51. The adders 23A to 23C add the outputs of the integrators 17A to 17C held at different phases, respectively.

FIG. 4 is a timing chart for explaining the operation of the circuit of FIG. 3. Since the integrator 17A is reset by the synchronizing signals 51 and 52, it is always reset at a half cycle of the power supply basic cycle. Integrate the output voltage for a half cycle. The holding circuit 21A holds the value of the integrator 17A with the synchronization signal 51. In FIG. 4, a value obtained by integrating a half period for outputting a negative voltage is held. The holding circuit 21B holds the value of the integrator 17A with the synchronization signal 52. In FIG. 4, a value obtained by integrating a half period for outputting a positive voltage is held. The values of the holding circuits 21A and 21B are added by the adder 23A. As can be seen from FIG. 4, the output of the adder 23A is updated at a half cycle of the power supply basic cycle, and an integral value of the immediately preceding cycle is obtained every half cycle. Adders 23A, 23B, 2
If the output voltage command value from the power control circuit 10 is corrected with the output of 3C, the correction can be performed in a half cycle of the power supply basic cycle, and higher-speed correction can be performed.

According to the second embodiment described above, the AC output voltage of the voltage-type self-excited converter is integrated by the integrators 17A to 17C in a half cycle of the power supply basic cycle.
By calculating the sum of the outputs of .about.17C and the output of the previous integrator, the DC voltage component included in the immediately preceding cycle can be detected every half cycle. If the converter output voltage command value of the next half cycle is corrected so as to cancel this DC voltage component, the DC component of the converter output voltage can be canceled at a higher speed. A control device for a voltage-type self-excited converter that can be operated stably can be provided. The integration is performed every half cycle, and the DC voltage component for the immediately preceding cycle is obtained by calculation. The DC voltage component is updated every half cycle, and the output voltage command value can be corrected every half cycle. Time is reduced and faster control is possible.

<Third Embodiment> FIG. 5 shows a third embodiment of the present invention.
FIG. 14 shows an embodiment (an embodiment corresponding to claim 3), which is a specific example of the voltage detector 15E for detecting the converter output phase voltage in the first embodiment or the second embodiment.
In FIG. 5, the amplifier 24 sets the DC voltage detection signal 53 to 1
/ 2. The inverting amplifier 25 inverts the polarity of the output signal of the amplifier 24. The analog switches 26A to 26C close when a logical 1 signal is input. An OR circuit 22B and an inverting circuit 27.

FIG. 6 is a diagram for explaining the operation of FIG. 5, and FIG. 6A is a diagram showing a part of the main circuit.
(B) is a timing chart for explaining the operation of (a) (relationship between converter output phase voltage and GTO on / off).
It is. The same elements as those in FIG. 6 which have already been described are denoted by the same reference numerals, and description thereof will be omitted. FIG. 6 shows one of the three-phase converters.
The phases are shown.

In FIG. 6, when the GTO 18A on the high voltage side is ignited, the AC side phase voltage VAC has a positive polarity and a voltage which is 1/2 of the DC voltage VDC. When the low-voltage side GTO 18B is fired, a voltage of 性 of the DC voltage VDC appears with a negative polarity. Therefore, if the rise time of the voltage and the like are ignored, the AC output phase voltage waveform can be estimated from the DC voltage and the firing pattern of the GTO.

Now, in FIG. 6, the high-pressure side GTO 18A
Is turned on, the analog switch 26A is closed and the DC voltage 53 is applied to the AC phase voltage signal 56 by the amplifier 24.
The voltage reduced to 1/2 is output. Low pressure side GTO18B
Is turned on, the analog switch 26B is closed, and the AC phase voltage signal 56 outputs a voltage of １ ／ of the DC voltage whose polarity is inverted by the inverting amplifier 25. In the dead time period in which both the high-side GTO 18A and the low-side GTO 18B are off, in a real circuit, when a current flows from the AC system in the direction of the DC side, the current has a positive polarity, and in the opposite direction, the DC has a negative polarity. A voltage that is の of the voltage is output. If the power factor does not change significantly during one cycle, the dead time period is the same as the period during which a positive voltage is output, and the period during which a negative voltage is output, so that there is no effect on the detection of DC components. Therefore, in FIG. 6, during the dead time period, the output of the OR circuit 22B becomes zero, the output is inverted by the inverting circuit 27, the analog switch 26C is turned on, and zero is output to the AC phase voltage signal 56. .

It is to be noted that a circuit for detecting the direction of the alternating current during the dead time and turning on one of the analog switches 26A and 26B may be used. The AC output voltage of a large-capacity converter such as a reactive power compensator or a DC power transmission device is usually a high voltage of several kV or more. In addition, since the voltage detector is a rectangular wave voltage, the voltage detector for the AC output phase voltage is required to have a high withstand voltage and a high speed, and is expensive. As in the embodiment of the present invention shown in FIG. 5, by calculating the AC output voltage from the detected value of the DC voltage and the firing command of the self-extinguishing element, a detector for the AC output phase voltage becomes unnecessary. An economical voltage-type self-excited converter control device can be provided.

<Fourth Embodiment> FIG. 7 shows a main part of a fourth embodiment of the present invention (an embodiment of the invention corresponding to claim 4), that is, a detector for the converter output phase voltage and an integrator. Things. In FIG. 7, the same elements as those already described are designated by the same reference numerals, and the description will be omitted. 7, the voltage frequency conversion circuit 28 changes the frequency according to the input DC voltage. The counter 29 counts an input clock signal. When an up command (high-pressure GTO on command) 54 is input, the clock counts up, and a down command (low-pressure GTO on command) 55 is input. When the clock counts down, the OR circuit 22
When a stop command is input via B and the inverting circuit 27, the counting is stopped, and when a reset command is input from the delay circuit 20A, the output of the counter 29 is initialized. Hold circuit (sample hold) 3
0 holds the count value of the counter 29.

The operation of FIG. 7 will be described with reference to the timing chart of FIG. In FIG. 8, the DC voltage decreases in the first cycle. When the DC voltage 53 decreases, the frequency of the voltage frequency conversion circuit 28 decreases, and the count speed of the counter 29 decreases. When the DC voltage 53 recovers, the frequency returns and the count speed recovers. Since the count speed decreases only during the count-up, the value of the counter 29 after one cycle becomes a negative value.
In FIG. 8, the period (A) in which the DC voltage is decreasing is a period in which the positive phase voltage is output, and the actual voltage also becomes a negative value when integrated for one cycle.

In FIG. 8, during the period (B), an abnormality occurs in which the voltage on the positive side of the PWM pattern becomes longer. In such a case, the period for counting up becomes longer,
The count value after one cycle integration is a positive value. The actual voltage also becomes a positive value after one cycle integration.

As can be seen from FIG. 8, the output voltage can be integrated by the circuit configuration shown in FIG. 7 both when the DC voltage fluctuates and when the PWM pattern fluctuates. According to the fourth embodiment described above, the counter 29 counts up while the high-voltage GTO is on and counts down while the low-voltage GTO is on, in synchronization with the output of the voltage frequency conversion circuit 28. In addition, it is not only economical because there is no need to measure the terminal voltage of the transformer side winding of the transformer, but also by configuring the integrator with a digital circuit, the offset and drift of the integrator can be reduced. An error in DC component detection can be reduced, and a more reliable self-excited converter control device can be provided.

<Fifth Embodiment> Next, FIG. 9 shows a fifth embodiment of the present invention.
This embodiment (embodiment of the invention corresponding to claim 5) shows a level detector 32 for detecting that the outputs of the integrators 17A to 17C of the first embodiment have exceeded a predetermined value. Then, when there is an output signal of the level detector 32, the AC output voltage command value of the voltage source converter based on the outputs of the integrators 17A to 17C is corrected. In FIG. 9, the same elements as those already described are denoted by the same reference numerals and description thereof will be omitted. In FIG. 9, the maximum value selector 31, the level detector 32, and the changeover switches 33A to 33C have a constant one-phase value of the integrated value of the converter output voltage of the power supply basic cycle held by the output of the level detector 32. When the value exceeds the value, the level detector 32 operates, the changeover switches 32A to 33C are switched to the output sides of the holding circuits 21A to 21C, the integral value is input to the demagnetization suppression control circuit 12, the correction amount is calculated, and the electric power is calculated. The output voltage reference value from control circuit 10 is corrected. When the integrated values held by the holding circuits 21A to 21C are small, the changeover switch is switched to the 0 side, and the input to the demagnetization suppression control circuit 12 is zero and is not corrected. Integrator 17A-
17C also integrates the steady-state offset and error of the measurement system, and therefore outputs a certain value even if the DC component included in the actual output voltage is zero. On the other hand, when the adjacent large-capacity transformer is turned on or the large-capacity capacitor is turned on, the system voltage is distorted, and when a DC voltage component is included in the converter output, a large DC component is generated as compared with the steady-state offset. When such a large DC component is generated, the level detector 32 operates, the changeover switches 33A to 33C are switched, the outputs of the integrators 17A to 17C are input to the demagnetization suppression control circuit 12, and correction is performed. Will be

According to the fifth embodiment described above, unnecessary correction due to a minute DC component due to an error of the integrator or the like is not performed, and the system voltage is reduced when an adjacent large-capacity transformer is turned on or a large-capacity capacitor is turned on. It is possible to provide a highly reliable self-excited converter control device that performs correction when distortion and DC voltage components are included in the converter output and suppresses the magnetic bias of the transformer.

<Sixth Embodiment> FIG. 10 shows a sixth embodiment (an embodiment of the invention corresponding to claim 6) of the present invention, wherein the outputs of the integrators 17A to 17C exceed a certain value. A level detector 32 for detecting that the AC output voltage command value of the voltage source converter based on the outputs of the adders 23A to 23C when there is an output signal of the level detector 32 It is. In FIG. 10, the same elements as those already described are denoted by the same reference numerals, and description thereof will be omitted.

When the value added by the adders 23A to 23C is large, the level detector 32 operates and the changeover switches 33A to 33C are switched to the output sides of the adders 23A to 23C. The addition value is input, the correction amount is calculated, and the output voltage reference value from the power control circuit 10 is corrected. When the value added by the adders 23A to 23C is small, the changeover switches 33A to 33C are switched to the 0 side, and the input to the demagnetization suppression control circuit 12 is zero and is not corrected. Since the integrators 17A to 17C also integrate the steady-state offset and error of the measurement system, they output a certain value even if the DC component included in the actual output voltage is zero. on the other hand,
When the adjacent large-capacity transformer is turned on or the large-capacity capacitor is turned on, the system voltage is distorted, and when a DC voltage component is included in the converter output, a large DC component is generated as compared with the steady-state offset. When such a large DC component is generated, the level detector 32 operates and the changeover switches 33A to 33A.
33C is switched, and the outputs of the integrators 17A to 17C are input to the demagnetization suppression control circuit 12 to perform correction.

According to the sixth embodiment described above, unnecessary correction due to a minute DC component due to an error of the integrator or the like is not performed, and the system voltage is changed when the adjacent large-capacity transformer is turned on or the large-capacity capacitor is turned on. It is possible to provide a highly reliable and high-speed control device for a voltage-type self-excited converter that performs correction when distortion and a DC voltage component is included in the output of the converter and suppresses the magnetization of the transformer.

[0050]

According to the present invention, in a voltage-type self-excited converter, the transformer for a converter is saturated even when the system voltage is distorted due to the input of an adjacent large-capacity transformer or the input of a large-capacity capacitor. A control device for a voltage-type self-excited converter that can operate stably without overcurrent can be provided.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a control device for a voltage-type self-excited converter according to the present invention.
FIG. 3 is a circuit diagram showing an embodiment.

FIG. 2 is a diagram showing the circuit of FIG. 1 in detail.

FIG. 3 shows a second embodiment of the control device of the voltage source self-excited converter according to the present invention.
FIG. 3 is a circuit diagram showing an embodiment.

FIG. 4 is a timing chart for explaining the operation of FIG. 3;

FIG. 5 is a third embodiment of the control device for the voltage-source self-excited converter according to the present invention.
FIG. 2 is a circuit diagram showing a main part of the embodiment.

FIG. 6 is a diagram for explaining the operation of FIG. 5;

FIG. 7 shows a fourth embodiment of the control device of the voltage source self-excited converter according to the present invention.
FIG. 2 is a circuit diagram showing a main part of the embodiment.

FIG. 8 is a timing chart for explaining the operation of FIG. 7;

FIG. 9 shows a fifth embodiment of the control device for the voltage-source self-excited converter according to the present invention.
FIG. 3 is a circuit diagram showing an embodiment.

FIG. 10 is a circuit diagram showing a sixth embodiment of the control device of the voltage source self-excited converter according to the present invention.

FIG. 11 is a diagram showing an example of a control device of a conventional voltage-type self-excited converter.

FIG. 12 is a view for explaining a converter output voltage waveform during normal operation in FIG. 11;

FIG. 13 is a diagram for explaining a converter output voltage waveform when the system voltage in FIG. 11 is distorted.

[Explanation of symbols]

1, 1A-1C: power system, 2: transformer for instrument, 3: current detector, 4: transformer for converter, 5A-5D: current detector, 6A-6D: self-excited converter, 7: DC voltage Detector,
8A-8B: DC voltage source, 9: Power detector, 10: Power control circuit, 11: DC component detection circuit, 12: Demagnetization suppression control circuit, 13: Pulse width modulation circuit, 14: Pulse amplifier,
15A to 15E: voltage detector, 16: synchronization detector, 1
7, 17A to 17C: integrator, 18A to 18D: GTO
(Self-extinguishing element), 19A to 19D: diode, 20
... Delay circuits, 21A to 21C ... Hold circuits, 22A ... OR circuits, 23, 23A to 23C ... Adders, 24 ... Amplifiers, 25 ... Inverting amplifiers, 26A to 26C ... Analog switches, 27 ... Inverting circuits, 28 ... Voltage Frequency conversion circuit, 2
9 counter, 30 holding circuit, 31 maximum value detector,
32: level detector, 33A to 33C: changeover switch,
51, 52: power supply synchronization signal, 53: DC voltage detection signal,
54: High-pressure side GTO ON command, 55: Low-pressure side GTO ON command, 56: AC phase voltage signal.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 7/757 H02M 7/155 H02M 7/48

Claims (6)

(57) [Claims] 1. A power converter for bridging a self-extinguishing element and converting DC to AC or AC to DC,
A transformer having an AC terminal side of the power converter and converting an AC power system voltage to a desired value, and a voltage source self-excited converter including a DC voltage source having a DC terminal side of the power converter, Integrating means for integrating the AC output voltage of the power converter in a power supply basic cycle; and correcting means for correcting a voltage command value of the AC output of the power converter based on an output of the integrating means. Control device for voltage source self-excited converter. 2. A power converter for bridging a self-extinguishing element and converting DC to AC or AC to DC.
A transformer having an AC terminal side of the power converter and converting an AC power system voltage to a desired value, and a voltage source self-excited converter including a DC voltage source having a DC terminal side of the power converter, Integrating means for integrating the AC output voltage of the power converter in a half cycle of a power supply basic cycle; adding means for calculating the sum of the output of the integrating means and the output of the previous integrating means; output of the adding means A control unit for correcting a voltage command value of an AC output of the power converter based on the control signal. 3. The control device for a voltage-type self-excited converter according to claim 1, wherein the AC output voltage is calculated from a DC voltage detection value and a firing command for a self-extinguishing element. Control device for voltage-type self-excited converter. 4. A control device for a voltage-type self-excited converter according to claim 1, wherein the integrating means for the AC output voltage comprises: a voltage frequency converting means for converting a detected value of the DC voltage into a frequency; Synchronized with the output of the voltage frequency conversion means,
A control device for a voltage-type self-excited converter, comprising: a counter that counts up while the high-voltage self-extinguishing element is on and counts down while the low-voltage self-extinguishing element is on. . 5. A power converter for bridging a self-extinguishing element and converting DC to AC or AC to DC,
A transformer having an AC terminal side of the power converter and converting an AC power system voltage to a desired value, and a voltage source self-excited converter including a DC voltage source having a DC terminal side of the power converter, Integrating means for integrating the AC output voltage of the power converter in a power supply basic cycle; level detecting means for detecting that the output of the integrating means has exceeded a certain value; and a detection signal is output from the level detecting means. And a correcting means for correcting the AC output voltage command value of the power converter based on the output of the integrating means. 6. A power converter for bridging a self-extinguishing element and converting direct current to alternating current or alternating current to direct current,
A transformer having an AC terminal side of the power converter and converting an AC power system voltage to a desired value, and a voltage source self-excited converter including a DC voltage source having a DC terminal side of the power converter, Integrating means for integrating the AC output voltage of the power converter in a half cycle of a power supply basic cycle; adding means for calculating the sum of the output of the integrating means and the output of the previous integrating means; output of the adding means And a level detecting means for detecting that the output of the power converter has exceeded a predetermined value. An AC output voltage command value of the power converter based on an output of the adding means when a detection signal is output from the level detecting means. And a control unit for the voltage-source self-excited converter, comprising: