JPH07337037A - Controller for voltage self-excited converter - Google Patents

Abstract

PURPOSE:To obtain a controller for a voltage self-excited converter in which the converter can be operated stably without causing overcurrent due to saturation of a converter transformer even if the system voltage is distorted upon throw-in of an adjacent high capacity transformer or a high capacitance capacitor. CONSTITUTION:A voltage self-excited converter comprises a converter 4 for converting the voltage of an AC system 1 into a desired voltage, and converters 6A-6D comprising self-extinguishing elements connected in bridge and converting a DC voltage into an AC voltage or vice versa. The voltage self-excited converter further comprises an integrator 17 for integrating the AC output voltage from the converter at the basic period of power supply, and means for correcting the command value of AC output voltage from the voltage self-excited converter.

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 transmission device, a fuel cell system, etc., and a self-extinguishing element (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, a rectifier, etc. on the DC terminal side of the bridge-connected converter and a transformer that converts the AC power system voltage to a desired value on the AC terminal side of the power converter. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage-type self-excited converter control device in which an eccentricity suppression control circuit for a transformer installed between a converter and an electric power system is improved.

[0002]

2. Description of the Related Art Conventionally, a transformer for transformer is provided between an AC power system and a voltage type self-excited converter so that the AC system voltage has a desired value. For prevention, there is a control device for a voltage-type self-excited converter to which a bias magnetic suppression control circuit that suppresses bias magnetism is controlled by the DC component of the output current of the converter.

FIG. 11 is a diagram for explaining this.
It is configured as follows. That is, the power system 1, the instrument transformer 2 for measuring the system voltage, the current detector 3 for measuring the output current to the power system 1, and the transformer transformer 4
It consists of The transformer transformer 4 has the windings on the system side 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 GTOs, respectively.
The output current of the self-excited converters 6A to 6D composed of (gate turn-off thyristor) is detected. 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 electric power detector 9 detects the system voltage detected by the transformer 2 for an instrument and the output current to the electric power system 1 detected by the current detector 3,
The active power and reactive power output to the power grid 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, and controls the active power and the reactive power of the converters 6A to 6D. The magnetic bias suppression control circuit 12 corrects the output voltage command value output from the power control circuit 10 by 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 magnetic bias suppression control circuit 1.
On / off of the self-extinguishing element is determined based on the output voltage command value corrected in 2. A pulse amplifier (PA) 14 amplifies the pulse obtained from the pulse width modulation circuit 13 and supplies it to each self-extinguishing element.

In FIG. 11, the power control circuit 1 is normally operated.
0 and the pulse width modulation circuit 13 are self-excited converters 6A to 6A.
The GTO firing pattern is determined so that the output voltage of D does not include a DC component. However, the actual output voltage is
The waveform has a DC component due to variations in the characteristics of the gate signal and variations in the transmission time of the gate signal. When the output voltage of the self-excited converters 6A to 6D includes a DC component, the voltage-time product per cycle applied to the converter transformer 4 does not become 0, so that the iron core of the transformer 4 gradually deviates. It becomes magnetized, the exciting current increases, and it goes into overcurrent, and the self-exciting converters 6A to 6D stop protection. In the worst case, the self-extinguishing elements forming the self-exciting converters 6A to 6D may be damaged.

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

[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 modulated 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 the characteristics of the GTO and variations in the transmission time of the gate signal.

However, in a substation in which a large-capacity reactive power compensator or a self-exciting converter applied to direct current 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 overcurrent due to the distortion. FIG. 13 shows a waveform when the pulse width modulation is performed based on the output voltage command value thus distorted.

FIG. 13 shows 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 is contained at 25% of the amplitude of the sine wave and a phase difference of 90 degrees. is there.
In the converter output phase voltage of FIG. 13, the voltage on the negative side increases in the shaded area as compared with FIG. 12 in which the modulated wave does not include harmonics,
The voltage on the positive side increases along the vertical line, and when subtracted, a positive DC voltage is generated. That is, if the modulated wave is distorted, the converter output voltage after pulse width modulation will contain the DC component even if the integrated value of one period of the modulated wave does not contain the DC component.

For example, when 4% of the second harmonic is included, the value reaches 5% of the peak value of the voltage-time integral of the rated voltage of the transformer as a DC component per cycle. Assuming that the rated magnetic flux density during normal operation of the transformer is ⅔ of the saturated magnetic flux density, this is a value at which the transformer is saturated in about 10 cycles.

Such a demagnetization due to a DC voltage component having a larger value than that during normal operation cannot be made in time by the correction of the DC component of the converter DC winding current shown in FIG. 11, and the demagnetization progresses to cause an overcurrent. There was a problem that the system stopped.

An object of the present invention is to eliminate the above-mentioned problems, and in a voltage type self-exciting converter, the system voltage is distorted due to the turning on of an adjacent large capacity transformer or the turning on of a large capacity capacitor. Even in such a case, it is another object of the present invention to provide a control device for a voltage-type self-excited converter that can be stably operated without saturation of the converter transformer and overcurrent.

[0014]

In order to achieve the above-mentioned object, the invention corresponding to claim 1 is a power conversion in which a self-extinguishing element is bridge-connected to convert direct current to alternating current or alternating current to direct current. And a transformer that has an AC terminal side of this power converter and converts the AC power system voltage to a desired value,
In a voltage type self-exciting converter including a DC voltage source provided on the DC terminal side of the power converter, an integrating means for integrating the AC output voltage of the power converter in a power source basic cycle, and an output of the integrating means. The control device for the voltage-type self-excited converter further comprises a correction unit that corrects the voltage command value of the AC output of the power converter.

In order to achieve the above-mentioned object, the invention corresponding to claim 2 is a power converter which bridge-connects a self-extinguishing element and converts direct current into alternating current or alternating current into direct current, and this power conversion. In the voltage type self-exciting converter comprising a transformer for converting the AC power system voltage to a desired value on the AC terminal side of the power converter and a DC voltage source for the DC terminal side of the power converter, the power conversion Integrating means for integrating the AC output voltage of the power source in a cycle of half of the power source basic cycle, adding means for calculating the sum of the output of this integrating means and the output of the previous integrating means, and the output of this adding means The control device for the voltage-type self-excited converter further comprises a correction unit that corrects the voltage command value of the AC output of the power converter.

In order to achieve the above-mentioned object, the invention corresponding to claim 3 is the control device for a voltage type self-excited converter according to claim 1 or claim 2, wherein the AC output voltage is a DC voltage detection value. And a control device for a voltage type self-exciting converter, which is characterized in that it is calculated from a firing command of a self-extinguishing element.

In order to achieve the above-mentioned object, the invention corresponding to claim 4 is the control device of the voltage type self-excited converter according to claim 1 or claim 2, wherein the integrating means of the AC output voltage is a direct current. In synchronization with the voltage frequency conversion means for converting the detected voltage value into frequency, and the output of this voltage frequency conversion means, the high-voltage side self-extinguishing element counts up while the low-voltage side self-extinguishing element turns on. The control device for the voltage-type self-excited converter is characterized in that it is configured by a counter that counts down during the period.

In order to achieve the above-mentioned object, the invention corresponding to claim 5 relates to a power converter which bridge-connects a self-extinguishing element to convert direct current to alternating current or alternating current to direct current, and this power conversion. In the voltage type self-exciting converter comprising a transformer for converting the AC power system voltage to a desired value on the AC terminal side of the power converter and a DC voltage source for the DC terminal side of the power converter, the power conversion Means for integrating the AC output voltage of the power source in the basic cycle of the power source, level detecting means for detecting that the output of the integrating means exceeds a certain value, and when a detection signal is output from the level detecting means ,
A control device for a voltage-type self-excited converter, comprising: a correction unit that corrects the AC output voltage command value of the power converter based on the output of the integration unit.

In order to achieve the above-mentioned object, the invention according to claim 6 relates to a power converter which bridge-connects a self-extinguishing element and converts direct current into alternating current or alternating current into direct current, and this power conversion. In the voltage type self-exciting converter comprising a transformer for converting the AC power system voltage to a desired value on the AC terminal side of the power converter and a DC voltage source for the DC terminal side of the power converter, the power conversion Means for integrating the AC output voltage of the power source in a cycle of half the power source basic cycle, an adding means for calculating the sum of the output of this integrating means and the output of the previous integrating means, and the output of this adding means is constant. Level detection means for detecting that the value exceeds the value, and when the detection signal is output from the level detection means, corrects the AC output voltage command value of the power converter based on the output of the addition means. Correction means, A control device for Bei the voltage type self-commutated converter.

[0020]

According to the invention corresponding to claim 1, the AC output voltage of the power converter is integrated by the integrating means in the basic period of the power source, and the DC voltage component contained in the converter output voltage detected by the integrating means is canceled. By correcting the converter output voltage command value for the next cycle as described above, the system voltage is distorted due to the turning on of the large-capacity transformer and the turning-on of the large-capacity capacitor, and when the converter output contains a DC voltage component, Also, it is possible to provide a control device of a voltage type self-excited converter that can suppress the direct current component at high speed and can operate stably without causing an over-magnetization overcurrent.

According to the invention corresponding to claim 2, the AC output voltage of the power converter is integrated by the integrating means in a cycle of half the power source basic cycle, and the sum of this 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 for the next half cycle is corrected so as to cancel the DC voltage component, the DC component can be canceled even faster, so stable operation is achieved without causing an overcurrent of the magnetic bias. A control device for a voltage type self-exciting converter can be provided. Further, the integration is performed every half cycle, and the direct current voltage component for the immediately preceding one cycle is obtained by calculation, so that the direct current voltage component is updated every half cycle and the output voltage command value can be corrected every half cycle. Dead time is reduced and faster control is possible.

According to the invention corresponding to claim 3, in the control device according to claim 1 or 2, the alternating current output voltage is output as the positive polarity of the direct current voltage during the period when the high voltage side element is ignited. , The DC voltage is output in the negative polarity during the ignition period of the low voltage side element, so by detecting it by calculation, the measuring device for the terminal voltage of the transformer side winding of the transformer becomes unnecessary, It is possible to provide an economical control device for a self-excited converter.

According to the invention corresponding to claim 4, since the integrating means is constituted by a digital circuit, the measuring device for the terminal voltage of the transformer side winding of the transformer becomes unnecessary, which is not only economical but also economical. The DC component detection error due to the offset or drift of the integrating means can be reduced, and a more reliable self-excited converter control device can be provided.

According to the invention corresponding to claim 5, when the value of the DC voltage component which is the output of the integrating means exceeds a certain value, the AC output voltage of the power converter which is based on the output of the integrating means. Since the command value is corrected, unnecessary correction due to minute DC component due to error of integration means etc. is not performed, and the system voltage is distorted and converted when the adjacent large capacity transformer or large capacity capacitor is turned on. It is possible to provide a highly reliable controller for a self-exciting converter that suppresses the magnetic bias of the transformer by performing correction when the output of the transformer includes a DC voltage component.

Further, the invention according to claim 6 is such that when it is detected that the output of the adding means for calculating the sum of the output of the integrating means and the output of the previous integrating means exceeds a certain value, 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 of the integration means etc. is not performed, and an adjacent large capacity transformer can be turned on or off. Reliable and high-speed self-excited converter control device that suppresses transformer bias magnetism by correcting when the system voltage is distorted due to the input of a large capacity capacitor and the converter output contains a DC voltage component 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. Figure 1
11, the same elements as those already described in FIG. 11 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 1, the voltage detectors 15A to 15D measure the converter output voltage. The synchronization detector 16 is composed of, for example, a phase-locked loop circuit (PLL), inputs the system voltage measured by the instrument transformer 2,
Generates a pulse synchronized with the grid voltage. The integrating circuit 17 converts the converter output voltage detected by the AC voltage detector 15D into
Integration is performed for each system voltage basic cycle detected by the synchronization detector 16. For the sake of simplicity, the integrating circuit 17 only shows an integrating circuit of the output voltage of the converter 6D, but the converters 6A to 6A are shown.
Similarly, the output voltage is corrected by being provided to C as well.

FIG. 2 is a diagram showing in detail one converter in FIG. 1, and FIG. 1 already explained in FIG.
1 and the same elements as those in FIG. In FIG. 2, the converter is a self-extinguishing device such as a GTO.
18A to 18F, diodes 19A to 19F connected in antiparallel to these, and DC voltage sources 8A and 8B such as capacitors.

The delay circuit 20 includes the integrating circuits 17A to 17A.
Hold circuit (hold circuit) 21A to 21C for the value of 17C
Is a circuit for resetting the integrating circuits 17A to 17C after holding. The delay time of the delay circuit 20 is sufficient to be held by the holding circuits 21A to 21C and needs to be 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. 1 and 2. If the system voltage is not distorted and is sinusoidal, the converter output phase voltage becomes equal to the positive side voltage and the negative side voltage as already shown in FIG. If the output voltage is positive and negative, the holding circuit 2 is set for each system fundamental cycle detected by the synchronization detector 16 in FIG.
The outputs of the integrators 17A to 17C held by 1A to 21C become zero.

However, if the system voltage is greatly distorted when a large capacity power capacitor is turned on or an adjacent large capacity transformer is turned on, as shown in FIG. 13, the converter output phase voltage has a waveform including a DC component. Becomes Then, the integrator 17A
In the holding circuits 21A to 21C that hold the outputs of C to C in each system basic period, the difference between the integrated value of the positive side voltage and the integrated value of the negative side voltage, that is, from the area of the shaded portion to the vertical line portion in FIG. The output minus the area. The bias amount suppression control circuit 12 determines a correction amount so as to cancel the DC component for one cycle of the power source basic cycle held by the holding circuits 21A to 21C, and the output voltage command from the power control circuit 10 is determined. If the value is corrected, the output DC 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 type self-exciting converter in the power source basic cycle are provided, and the conversion detected by the integrators 17A to 17C is provided. By correcting the converter output voltage command value of the next cycle so as to cancel the DC voltage component included in the converter output voltage, the system voltage is distorted and converted when the adjacent large capacity transformer or large capacity capacitor is turned on. 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 even when the output of the transformer includes a direct current voltage component, and can operate stably without causing an overcurrent of the demagnetization.

<Second Embodiment> FIG. 3 shows a second embodiment of the present invention (an embodiment of the invention corresponding to claim 2).
The same elements as those already described with reference to FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. It is the figure shown about one self-exciting converter in the system of FIG. 1 like FIG. 3 and FIG. 2, and the same circuit is added also to the remaining three.

In FIG. 3, synchronization signals (output signals) 51 and 52 from the synchronization detector 16 are signals that are output at each basic cycle of the power supply and are 180 degrees out of phase with each other. The OR circuit 22 ORs the synchronization signals 51 and 52 from the synchronization detector 16. Of the holding circuits 21A to 21F, the holding circuits 21A, 21C, and 21E hold the value by the synchronization signal 51 of the synchronization detector 16, and the holding circuits 21B, 21D, and 21F.
F holds a value as a 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 in 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 synchronization signals 51 and 52, it is always reset at half the power supply basic cycle, Integrate the output voltage for 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 cycle 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 cycle for outputting a positive voltage is held. The adder 23A adds the values of the holding circuits 21A and 21B. 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 the integrated value of the immediately preceding one 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 cycle that is half the power supply basic cycle, and faster correction is possible.

According to the second embodiment described above, the AC output voltage of the voltage-type self-exciting converter is integrated by the integrators 17A to 17C at a half cycle of the power source basic cycle to obtain the integrator 17A.
By calculating the sum of the output of ~ 17C and the output of the previous integrator, the DC voltage component included in the immediately preceding one 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 even faster, so that there is no bias magnetic overcurrent, It is possible to provide a control device for a voltage type self-exciting converter that can be stably operated. By performing the integration every half cycle and obtaining the DC voltage component for the immediately preceding one cycle 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.
An embodiment (an embodiment corresponding to claim 3) is shown, 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 outputs the DC voltage detection signal 53 to 1
Set to / 2. The inverting amplifier 25 inverts the polarity of the output signal of the amplifier 24. The analog switches 26A to 26C are closed when a logic 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 on / off of GTO)
Is. The same elements as those already described with reference to FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. FIG. 6 shows a three-phase converter 1
The phases are shown.

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

Now, referring to FIG. 6, the high voltage side GTO 18A
When the ON command 54 is input, the analog switch 26A is closed, and the DC voltage 53 is supplied to the amplifier 24 as the AC phase voltage signal 56.
The voltage halved is output. Low voltage side GTO18B
When the ON command 55 is input, the analog switch 26B is closed, and as the AC phase voltage signal 56, a voltage which is ½ of the DC voltage whose polarity is inverted by the inverting amplifier 25 is output. During the dead time period in which both the high-voltage side GTO 18A and the low-voltage side GTO 18B are off, in the actual circuit, when the current is flowing from the AC system in the direction of the DC side, the polarity is positive, and in the opposite direction, the polarity is negative. A voltage that is half 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 for outputting a positive voltage and the period for outputting a negative voltage, so there is no effect on the detection of the DC component. Therefore, in FIG. 6, in the dead time period, the output of the OR circuit 22B becomes zero, the output is inverted by the inversion circuit 27, the analog switch 26C is turned on, and zero is output to the AC phase voltage signal 56. .

A circuit for detecting the direction of the alternating current during the dead time and turning on either the analog switch 26A or 26B may be used. The AC output voltage of a large-capacity converter such as a reactive power compensating device or a DC power transmitting device is usually a high voltage of several kV or more. Further, since it is a rectangular wave voltage, the voltage detector of the AC output phase voltage is required to have high withstand voltage and high speed, which is expensive. As in one 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, the detector of the AC output phase voltage becomes unnecessary, It is possible to provide an economical control device for a voltage type self-excited converter.

<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 converter output phase voltage detector and an integrator. It is a thing. In FIG. 7, the same elements as those already described are designated by the same reference numerals and the description thereof will be omitted. In FIG. 7, the voltage frequency conversion circuit 28 changes the frequency according to the input DC voltage. The counter 29 counts the input clock signal, counts up the clock when the up command (high voltage side GTO ON command) 54 is input, and inputs the down command (low voltage side GTO ON command) 55. When the clock is counted down, the OR circuit 22
It has a function of stopping counting when a stop command is input through B and the inversion circuit 27 and initializing the output of the counter 29 when a reset command is input from the delay circuit 20A. Holding 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 middle of 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 is restored, the frequency is restored and the count speed is restored. Since the count speed decreases only during counting 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 the period in which the positive phase voltage is output, and the actual voltage also has a negative value when integrated for one cycle.

In the period (B) in FIG. 8, there is an abnormality that the voltage on the positive side of the PWM pattern becomes long. In such a case, the period for counting up becomes longer,
The count value after one-cycle integration becomes a positive value. The actual voltage also becomes a positive value when integrated over one cycle.

As can be seen from FIG. 8, the output voltage can be integrated with the circuit configuration shown in FIG. 7 regardless of whether the DC voltage changes or the PWM pattern changes. According to the fourth embodiment described above, the counter 29 is synchronized with the output of the voltage frequency conversion circuit 28 and counts up while the high voltage side GTO is on, and counts down while the low voltage side GTO is on. Since it is composed of, it is not only economical because it does not require a measuring device for the terminal voltage of the transformer side winding of the transformer, but also because the integrator is composed of a digital circuit, it is An error in DC component detection can be reduced, and a more reliable self-excited converter control device can be provided.

<Fifth Embodiment> FIG. 9 shows a fifth embodiment of the present invention.
The embodiment (embodiment of the invention corresponding to claim 5) is shown, which comprises a level detector 32 for detecting that the outputs of the integrators 17A to 17C of the first embodiment have exceeded a certain value. However, 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 designated by the same reference numerals and the description thereof will be omitted. In FIG. 9, the maximum value selector 31, the level detector 32, and the change-over switches 33A to 33C are such that the value of one phase of the integrated value of the converter output voltage of the power supply basic period held at the output of the level detector 32 is constant. When the value exceeds the value, the level detector 32 operates, the changeover switches 32A to 33C are switched to the output side of the holding circuits 21A to 21C, the integrated value is input to the bias magnetic suppression control circuit 12, the correction amount is calculated, and the power is calculated. The output voltage reference value from the control circuit 10 is corrected. When the integrated value held in the holding circuits 21A to 21C is small, the changeover switch is switched to the 0 side, and the input to the magnetic bias suppression control circuit 12 becomes zero and is not corrected. Integrator 17A ~
Since 17C also integrates the steady offset and error of the measurement system, it outputs a certain value even if the DC component contained in the actual output voltage is zero. On the other hand, when the system voltage is distorted due to the turning on of the adjacent large-capacity transformer and the turning-on of the large-capacity capacitor, and when the converter output contains a DC voltage component, a large DC component is generated as compared with the steady 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 bias magnetic suppression control circuit 12, and correction is performed. Be seen.

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 changed when the adjacent large capacity transformer or large capacity capacitor is turned on. It is possible to provide a highly reliable controller for a self-exciting converter that suppresses bias magnetizing of a transformer by performing correction when a distortion and a converter output include a DC voltage component.

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

When the value added by the adders 23A to 23C is large, the level detector 32 operates, the changeover switches 33A to 33C are switched to the output side of the adders 23A to 23C, and the bias magnetic suppression control circuit 12 is operated. The added 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 magnetic bias suppression control circuit 12 becomes zero and is not corrected. Since the integrators 17A to 17C also integrate the stationary offset and error of the measurement system, they output a certain value even if the DC component contained 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 the converter output includes a DC voltage component, a large DC component is generated as compared with the steady offset. When such a large DC component is generated, the level detector 32 operates and the changeover switches 33A ...
33C is switched, and the outputs of the integrators 17A to 17C are input to the magnetic bias suppression control circuit 12 to be corrected.

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

[0050]

According to the present invention, in the voltage type self-exciting converter, the transformer for transformer is saturated even when the system voltage is distorted due to the turning on of the adjacent large capacity transformer or the turning on of the large capacity capacitor. It is possible to provide a control device for a voltage type self-exciting converter that can be stably operated without causing an overcurrent.

[Brief description of drawings]

FIG. 1 is a first block diagram of a control device for a voltage type self-excited converter according to the present invention.
The circuit diagram which shows an Example.

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

FIG. 3 is a second control device for the voltage source self-exciting converter according to the present invention.
The circuit diagram which shows an Example.

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

FIG. 5 is a third control device for the voltage source self-exciting converter according to the present invention.
FIG. 3 is a circuit diagram showing a main part of the embodiment.

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

FIG. 7 is a fourth diagram of the control device for the voltage source self-exciting converter of the present invention.
FIG. 3 is a circuit diagram showing a main part of the embodiment.

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

FIG. 9 is a fifth embodiment of the control device for the voltage source self-exciting converter of the present invention.
The circuit diagram which shows an Example.

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

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

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

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

[Explanation of symbols]

1, 1A to 1C ... Power system, 2 ... Instrument transformer, 3 ... Current detector, 4 ... Converter transformer, 5A-5D ... Current detector, 6A-6D ... Self-exciting converter, 7 ... DC voltage Detector,
8A to 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 ... Synchronous detector, 1
7, 17A to 17C ... Integrator, 18A to 18D ... GTO
(Self-extinguishing element), 19A to 19D ... Diode, 20
... delay circuit, 21A-21C ... holding circuit, 22A ... OR circuit, 23, 23A-23C ... adder, 24 ... amplifier, 25 ... inverting amplifier, 26A-26C ... analog switch, 27 ... inverting circuit, 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 voltage side GTO ON command, 55 ... Low voltage side GTO ON command, 56 ... AC phase voltage signal.

Claims (6)

[Claims] 1. A power converter for connecting a self-extinguishing element to a bridge to convert direct current to alternating current or alternating current to direct current,
In a voltage type self-exciting converter having a transformer for converting the AC power system voltage to a desired value and having the AC terminal side of the power converter, and a DC voltage source having the DC terminal side of the power converter, An integrating means for integrating the AC output voltage of the power converter in a power source basic cycle; and a correcting means for correcting the voltage command value of the AC output of the power converter based on the output of the integrating means. Control device for voltage type self-exciting converter. 2. A power converter which bridge-connects self-extinguishing elements and converts direct current into alternating current or alternating current into direct current,
In a voltage type self-exciting converter having a transformer for converting the AC power system voltage to a desired value and having the AC terminal side of the power converter, and a DC voltage source having the DC terminal side of the power converter, Integrating means for integrating the AC output voltage of the power converter in a cycle of a power source basic cycle, adding means for calculating the sum of the output of this integrating means and the output of the previous integrating means, and the output of this adding means A control device for a voltage-type self-excited converter, comprising: a correction unit that corrects the voltage command value of the AC output of the power converter. 3. The control device for a voltage type self-exciting converter according to claim 1 or 2, wherein an AC output voltage is calculated from a DC voltage detection value and a firing command of a self-extinguishing element. Voltage source self-exciting converter control device. 4. The control device for a voltage type self-exciting converter according to claim 1 or 2, wherein the integrating means of the AC output voltage is a voltage frequency converting means for converting the 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-exciting converter, which comprises a counter that counts up while the high-voltage side self-extinguishing element is on, and counts down while the low-voltage side self-extinguishing element is on. . 5. A power converter that bridge-connects a self-extinguishing element to convert direct current to alternating current or alternating current to direct current,
In a voltage type self-exciting converter having a transformer for converting the AC power system voltage to a desired value and having the AC terminal side of the power converter, and a DC voltage source having the DC terminal side of the power converter, Integrating means for integrating the AC output voltage of the power converter in the power source basic cycle, level detecting means for detecting that the output of the integrating means exceeds a certain value, and a detection signal is output from the level detecting means. And a correction unit that corrects the AC output voltage command value of the power converter based on the output of the integration unit. 6. A power converter for connecting a self-extinguishing element to a bridge and converting direct current to alternating current or alternating current to direct current,
In a voltage type self-exciting converter having a transformer for converting the AC power system voltage to a desired value and having the AC terminal side of the power converter, and a DC voltage source having the DC terminal side of the power converter, Integrating means for integrating the AC output voltage of the power converter in a cycle of a power source basic cycle, adding means for calculating the sum of the output of this integrating means and the output of the previous integrating means, and the output of this adding means Of the AC output voltage command value of the power converter based on the output of the adding means when a detection signal is being output from the level detecting means. A voltage source self-exciting converter control device comprising: