JP2008263759A - Biased magnetization suppression control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biased magnetization suppression control unit capable of detecting biased magnetization without any detection delay even if instantaneous biased magnetization occurs in a transformer, and capable of suppressing and controlling the biased magnetization in the transformer quickly. <P>SOLUTION: The biased magnetization suppression control unit has: a magnetic flux estimate operation section 5 for obtaining an estimate of magnetic flux in the transformer 22 from voltage applied to the transformer 22 connected to a bus to which a power converter 1 is connected; a magnetic flux setting value operation section 4 for obtaining a setting value of magnetic flux in the transformer 22 from the voltage reference of the power converter 1; and a biased magnetization amount-of-compensation operation section 6 for obtaining the amount of biased magnetization to be corrected in the transformer 22 from the amount of magnetic flux deviation that is the difference between the magnetic flux setting value and the magnetic flux estimate. The biased magnetization suppression control unit adds the amount of correction of biased magnetization to the voltage command value of the power converter 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a demagnetization suppression control device that suppresses the demagnetization of a transformer connected to the output side of a power converter that converts direct current into alternating current.

  A power converter that is connected to an electric power system and is operated cannot be stably operated when a magnetism occurs in a transformer connected to a load bus. For this reason, a demagnetization suppression control device that suppresses the demagnetization of the transformer is required for the power converter.

  In the conventional demagnetization suppression control device, the direct current supplied from the direct current power source is converted into alternating current, and the output voltage or output current of the power converter supplied to the load via the transformer is controlled so as to follow the reference value. An automatic control circuit, means for obtaining a magnetic flux command value of the transformer from a signal corresponding to the output voltage of the transformer, magnetic flux detection means for detecting the magnetic flux of the transformer, and the magnetic flux command value and the detected magnetic flux A correction circuit that outputs a signal corresponding to the deviation signal, and the power converter is controlled by the sum of the output of the correction circuit and the output of the automatic control circuit, or the magnetic flux detection means An integrated value of the output of the automatic control circuit is used in place of the magnetic flux to be detected (Patent Document 1).

In addition, the conventional bias suppression control device integrates the voltage or current for a certain period before the time when the transformer bias suppression control is executed, detects the average value of the DC bias, and detects the DC bias. There is one that obtains a control amount using a magnetic amount and suppresses and controls bias magnetization (Patent Document 2).
JP-A-8-266069 Japanese Patent Laid-Open No. 9-14164

  In the demagnetization suppression control device described in Patent Document 1, there is a problem that the magnetic flux detection means must be built in the transformer in advance, and when the power converter is stopped and power is supplied from the system When the voltage fluctuates, there is a problem that the integrated value of the output of the automatic control circuit does not match the actual transformer magnetic flux and a large error occurs.

  In the demagnetization suppression control device described in Patent Document 2, the voltage applied to the transformer is integrated as a means for detecting the demagnetization of the transformer for a period that is an integral multiple of the power cycle. According to this method, the DC component due to the magnetic bias is detected as the time average value for a certain period. However, since the integration is used for the detection means, a delay occurs in the detection of the magnetic bias. For this reason, it is not possible to cope with a bias magnetism due to an instantaneous voltage change due to a failure or the like on the system side.

  If the operation of the power converter is continued with the bias magnetized, the transformer connected to the power supply will be saturated, and the power converter will not operate stably due to an overcurrent failure due to an increase in excitation current. . In addition, in order not to stop the power converter due to overcurrent, it is necessary to make the current rating several times that during steady operation, which increases the cost and increases the external shape of the device. is there.

  The present invention provides a demagnetization suppression control device capable of detecting a demagnetization without detection delay even when instantaneous demagnetization occurs in the transformer and quickly suppressing and controlling the demagnetization of the transformer. The purpose is to provide.

  In order to solve the above-mentioned problem, the bias suppression control device of the present invention is a magnetic flux estimation value for obtaining an estimated value of a magnetic flux of the transformer from a voltage applied to a transformer connected to a bus connected to a power converter. A calculating unit; a magnetic flux setting value calculating unit that obtains a setting value of the magnetic flux of the transformer from a voltage reference of the power converter; and the transformer from a magnetic flux deviation amount that is a difference between the magnetic flux setting value and the magnetic flux estimation value. And a demagnetization correction amount calculation unit for obtaining the demagnetization amount to be corrected, and adding the demagnetization correction amount to the voltage command value of the power converter.

  According to the demagnetization suppression control device of the present invention, even when instantaneous demagnetization occurs in the transformer, the demagnetization can be detected without detection delay, and the demagnetization of the transformer is quickly suppressed and controlled. be able to.

Hereinafter, a demagnetization suppression control apparatus according to first to ninth embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a configuration and a signal flow of the bias suppression control apparatus according to the first embodiment of the present invention.

  The power converter 1 is composed of a semiconductor element and is a device that converts DC power supplied from a DC power source 24 into AC power. A power source 35 (not shown) and a bus 35 connected to a system power source 7 having impedance. It is connected to the. A load 23 is connected to the bus 35 via a transformer 22. The demagnetization suppression control device includes a voltage detection unit 2, a magnetic flux set value calculation circuit 4, a magnetic flux estimated value calculation circuit 5, a demagnetization correction amount calculation circuit 6, a subtractor 25 and an adder 26.

  The magnetic flux generated in the transformer 22 during normal operation is calculated by the magnetic flux set value calculation circuit 4 as the magnetic flux set value, and the magnetic flux actually generated in the transformer 22 is calculated by the magnetic flux estimated value calculation circuit 5 Estimated magnetic flux. The subtractor 25 calculates the magnetic flux deviation amount by taking the difference between the magnetic flux setting value and the magnetic flux estimation value. The demagnetization correction amount calculation circuit 6 calculates and outputs a demagnetization correction amount corresponding to the magnetic flux deviation amount. By adding this bias correction amount to the voltage command value of the power converter 1 in the adder 26, the output voltage of the power converter 1 is changed in a direction to suppress the bias of the transformer 22.

  According to the present embodiment, even when an instantaneous demagnetization due to an instantaneous voltage change due to a failure on the system power supply 7 side or the like can be detected, the instantaneous demagnetization can be detected. Therefore, it is possible to provide a demagnetization suppression control device that can perform suppression control.

(Second Embodiment)
FIG. 2 is a diagram showing the configuration and signal flow of the magnetic flux set value calculation circuit 4 provided in the bias suppression control apparatus of the second embodiment of the present invention. The magnetic flux set value calculation circuit 4 includes a reference phase generator 27 and a 2-phase / 3-phase converter 11.

Since the magnetic flux of the transformer 22 is an integral of the voltage applied to the transformer 22, the magnetic flux of the transformer 22 in a steady state becomes a waveform that is 90 ° behind the voltage waveform. By the way, the power converter 1 has a reference value for the voltage and a reference value for the phase to be output by the transformer 22 in order to operate in conjunction with the system power supply 7. For this reason, when the 2-phase / 3-phase converter 11 performs an operation on the voltage reference using a signal delayed by 90 ° from the phase reference, a sinusoidal signal delayed by 90 ° from the voltage waveform to be output by the power converter 1. Is determined, and this is set as the magnetic flux setting value.
According to the present embodiment, it is possible to obtain an instantaneous value of the magnetic flux that should be generated in the transformer 22 in a steady state, and it can be used as a reference value of the magnetic flux.

(Third embodiment)
FIG. 3 is a diagram showing a configuration and signal flow of the magnetic flux estimated value calculation circuit 5 provided in the bias suppression control device of the third embodiment of the present invention. In other words, the magnetic flux estimated value calculation circuit 5 includes an integrator 9 and a DC component removal filter 10.

  The estimated magnetic flux of the transformer 22 to suppress the magnetic bias is obtained by integrating the voltage value input from the voltage detection unit 2 with the primary side voltage of the transformer 22 by the integrator 9, thereby obtaining the actual magnetic flux of the transformer 22. Ask for. When the output voltage is constant, the calculation result is a sinusoidal waveform. However, if there is an error in the arithmetic circuit due to factors such as rounding up or down by the number of significant digits or offset of the voltage detection unit 2, the error accumulates when integration is continued, and a DC component is superimposed on the estimated magnetic flux value. . In order to prevent this, the direct current component is removed by the direct current component removal filter 10 provided at the subsequent stage of the integrator 9. The DC component removal filter 10 is composed of a first-order lag element having a time constant sufficiently larger than the power supply period, and removes only the DC component included in the estimated magnetic flux value.

  According to the present embodiment, the direct current component is removed from the estimated magnetic flux value, and the accuracy of the estimated magnetic flux of the transformer 22 can be improved. Moreover, in the case of suppressing the demagnetization of the converter output transformer connected immediately after the power converter 1, the detection of the demagnetization of the converter output transformer is performed by the converter connected to the primary side of the transformer. Since the signal of the voltage detector used for voltage control is used, a dedicated detector for suppressing demagnetization such as a magnetic flux detector of a transformer becomes unnecessary. Since a dedicated detector is not required, it is easy to add a demagnetization suppression control unit to an existing device.

(Fourth embodiment)
FIG. 4 is a diagram showing the configuration and signal flow of the bias suppression control apparatus of the fourth embodiment of the present invention, and FIG. 5 shows the magnetic flux set value calculation provided in the bias suppression control apparatus of the present embodiment. It is a figure which shows the structure of a circuit 4, and the flow of a signal. The magnetic flux setting arithmetic circuit in the present embodiment includes a multiplier 29 which is a correction circuit for a voltage drop due to the impedance of the converter output transformer 28, an adder 30, a reference phase generator 27, and two-phase / 3. A phase converter 11 is provided.

  In the case where the power converter 1 is connected to the bus 35 via the converter output transformer 28 and suppresses the demagnetization of the transformer 22 connected to the bus 35, the converter output transformer 28 has Since a voltage drop occurs due to the impedance, if a value obtained by calculating the magnetic flux set value without correcting the voltage drop is used, a magnetic flux deviation always appears even in a steady state. Therefore, in the present embodiment, a voltage drop is obtained by multiplying the load current by the impedance of the converter output transformer 28 as a voltage drop due to the impedance of the converter output transformer 28, and voltage correction for this drop is performed. The magnetic flux set value is calculated using the value.

  According to the present embodiment, it is possible to correct the voltage drop due to the impedance of the converter output transformer 28, and to improve the calculation accuracy of the magnetic flux set value of the transformer 22 whose bias should be suppressed. it can.

(Fifth embodiment)
FIG. 6 is a diagram showing the configuration and signal flow of the bias correction amount calculating circuit 6 provided in the bias suppression control apparatus of the fifth embodiment of the present invention.

  The demagnetization correction amount calculation circuit 6 includes a level determination unit 12 that determines the level of the magnetic flux deviation amount and the changeover switch 13, and outputs the demagnetization correction amount that is calculated when the magnetic flux deviation amount becomes a set value or more. Further, when the value is equal to or less than the set value, zero is output without utilizing the suppression control.

  According to the present embodiment, in the case where a demagnetization that requires a small amount of demagnetization and does not need to be suppressed, the voltage is stably output without causing the fluctuation of the voltage due to the use of the demagnetization suppression control. be able to.

(Sixth embodiment)
FIG. 7 is a diagram showing the configuration and signal flow of the bias suppression control apparatus of the sixth embodiment of the present invention, and FIG. 8 shows the bias correction amount provided in the bias suppression control apparatus of the present embodiment. It is a figure which shows the structure of the arithmetic circuit 6, and the flow of a signal.

  The demagnetization suppression control device of this embodiment has a configuration in which a converter current detection unit 14 is added to the demagnetization suppression control device (FIG. 1) of the first embodiment, and the demagnetization correction amount calculation circuit 6 has a polarity. A determination unit 15 and two multipliers 31 and 32 are provided. The polarity of the demagnetization is determined from the amount of magnetic flux deviation calculated from the output of the magnetic flux set value calculation circuit 4 and the output of the magnetic flux estimated value calculation circuit 5. A value obtained by multiplying the converter current detected by the converter current detector 14 by the bias correction gain and the polarity is used as the bias correction amount. Since an appropriate bias correction gain varies depending on the characteristics of the device and the amount of bias deviation, an operator inputs it from the outside.

  When the magnetism is generated, the transformer 22 is saturated, and the current is remarkably increased by the exciting current of the transformer 22. In the present embodiment, the transformer 22 is used by using the current value during the magnetism. Therefore, the converter does not become overcurrent by the bias suppression control.

(Seventh embodiment)
FIG. 9 is a diagram showing the configuration and signal flow of the bias correction amount calculating circuit 6 provided in the bias suppression control apparatus of the seventh embodiment of the present invention.

The demagnetization correction amount calculation circuit 6 in the present embodiment includes a multiplier 33, and applies a demagnetization correction gain to the magnetic flux deviation amount obtained from the output of the magnetic flux set value calculation circuit 4 and the output of the magnetic flux estimation value calculation circuit 5. This is the bias correction amount. The strength of the demagnetization suppression can be determined in consideration of the balance between the demagnetization suppression and the voltage control.
According to the present embodiment, it is possible to perform the demagnetization suppression control using the magnetic flux deviation amount.

(Eighth embodiment)
FIG. 10 is a diagram showing the configuration and signal flow of the voltage command value calculation unit 8 provided in the demagnetization suppression control device of the eighth embodiment of the present invention. The voltage command value calculation unit 8 includes a constant voltage control activation circuit 17, and the constant voltage control activation circuit 17 includes a voltage command value changeover switch 18. Direct output as command value.

In the demagnetization suppression control, in order to suppress the demagnetization, a voltage is output in a direction opposite to the polarity of the demagnetization to vary the voltage. Further, the constant voltage control is performed so that the output voltage becomes constant. For this reason, if two controls are operating simultaneously, interference of control will arise, it will become impossible to suppress demagnetization, and there is a possibility that power converter 1 cannot be operated stably. Therefore, in the present embodiment, the voltage reference value is output as the voltage command value without using the constant voltage control while the bias suppression control ON signal is output during the bias suppression control.
Thus, according to the present embodiment, since the constant voltage control is not activated during the bias suppression control, the interference between the bias suppression control and the constant voltage control can be prevented and the power converter 1 can be operated stably.

(Ninth embodiment)
FIG. 11 is a diagram showing the configuration of the timer circuit 19 and the signal flow provided in the demagnetization suppression control device according to the ninth embodiment of the present invention. The timer circuit 19 includes a time setting circuit 20 and a counter 21.

  The counter 21 starts counting with the output of the demagnetization suppression control command. At the same time, a demagnetization suppression control ON command is output to the demagnetization correction amount calculation circuit 6 shown in FIG. The time setting circuit 20 is preset with a time of one cycle of the power supply frequency, and is multiplied by a setting value input from the setting value input unit for setting the operation time of the timer circuit 19. By setting the set value input as an integer input, the operation setting time of the timer circuit 19 is after an integer multiple of the power cycle. The timer circuit 19 starts counting with the demagnetization suppression control command, and when the operation set time is reached, the timer circuit 19 outputs a demagnetization suppression control off signal to the demagnetization correction amount calculation circuit 6. The demagnetization correction amount calculation circuit 6 ends the demagnetization suppression control when it receives the OFF signal from the timer circuit 19.

  According to the present embodiment, since the output of the demagnetization correction amount is controlled by the timer circuit 19 to a time that is an integral multiple of the power cycle, even if there is an offset in the demagnetization correction amount, the offset is within one cycle. It is possible to end the demagnetization suppression control in a state where only the integration is canceled and it is possible to prevent the occurrence of demagnetization due to the timing of the demagnetization suppression control off.

  In addition, each part, such as the magnetic flux set value calculation circuit 4, the magnetic flux estimation calculation circuit 5, and the demagnetization correction amount calculation circuit 6 in each of the above embodiments, may be configured by circuit parts such as a resistor, a capacitor, and a reactor. It may be realized by software.

The block diagram which shows the structure and signal flow of the bias-magnetization suppression control apparatus of the 1st Embodiment of this invention. The block diagram which shows the structure of the magnetic flux set value calculating circuit with which the bias-magnetization suppression control apparatus of the 2nd Embodiment of this invention is provided, and a signal flow. The block diagram which shows the structure of the magnetic flux estimated value calculating circuit with which the bias-magnetization suppression control apparatus of the 3rd Embodiment of this invention is provided, and a signal flow. The block diagram which shows the structure and signal flow of the bias-magnetization suppression control apparatus of the 4th Embodiment of this invention. The block diagram which shows the structure of the magnetic flux estimated value calculating circuit with which the bias-magnetization suppression control apparatus of the 4th Embodiment of this invention is provided, and a signal flow. The block diagram which shows the structure and signal flow of a bias correction amount calculating circuit with which the bias suppression control apparatus of the 5th Embodiment of this invention is equipped. The block diagram which shows the structure and signal flow of a demagnetization suppression control apparatus of the 6th Embodiment of this invention. The block diagram which shows the structure and signal flow of a demagnetization correction amount calculating circuit with which the demagnetization suppression control apparatus of the 6th Embodiment of this invention is equipped. The block diagram which shows the structure of the bias correction amount calculating circuit with which the bias suppression control apparatus of the 7th Embodiment of this invention is provided, and a signal flow. The block diagram which shows the structure of the voltage command value calculating part with which the bias-magnetization suppression control apparatus of the 8th Embodiment of this invention is provided, and the flow of a signal. The block diagram which shows the structure and signal flow of a timer circuit with which the demagnetization suppression control apparatus of the 9th Embodiment of this invention is equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Power converter, 2 ... Voltage detection part, 3 ... Voltage reference | standard input part, 4 ... Magnetic flux set value calculation circuit, 5 ... Magnetic flux estimated value calculation circuit, 6 ... Demagnetization correction amount calculation circuit, 7 ... System power supply, 8 DESCRIPTION OF SYMBOLS ... Voltage command value calculating part, 9 ... Integrator, 10 ... DC component removal filter, 11 ... 2-phase / 3-phase converter, 12 ... Level judgment device, 13 ... Demagnetization correction amount changeover switch, 14 ... Converter current detection 15, polarity determination unit, 16, constant voltage control unit, 17, constant voltage control activation circuit, 18, voltage command value changeover switch, 19, timer circuit, 20, time setting circuit, 21, counter, 22, transformer , 23 ... load, 24 ... DC power supply, 25 ... subtractor, 26 ... adder, 27 ... reference phase generator, 28 ... converter output transformer, 29 ... multiplier, 30 ... adder, 31, 32, 33 , 34 ... multiplier, 35 ... bus.

Claims (9)

  A magnetic flux estimated value calculation unit for obtaining an estimated value of the magnetic flux of the transformer from a voltage applied to a transformer connected to a bus connected to the power converter, and a magnetic flux of the transformer from a voltage reference of the power converter A magnetic flux set value calculating unit for obtaining a set value of the magnetic flux, and a magnetic bias correction amount calculating unit for obtaining a magnetic bias amount to be corrected by the transformer from a magnetic flux deviation amount that is a difference between the magnetic flux set value and the magnetic flux estimated value. A demagnetization suppression control device, wherein the demagnetization correction amount is added to a voltage command value of the power converter.   The magnetic flux set value calculation unit includes a reference phase generation unit and a two-phase / three-phase converter, and performs two-phase / three-phase conversion using a phase that is 90 ° behind the voltage reference and phase reference of the power converter. The bias suppression control device according to claim 1, wherein the magnetic flux set value is calculated.   3. The bias suppression control apparatus according to claim 2, wherein the magnetic flux set value calculation unit includes a correction circuit that corrects a voltage drop due to impedance of the converter output transformer.   2. The bias according to claim 1, wherein the magnetic flux estimated value calculation unit includes an integrator that integrates a detection voltage of the transformer, and a DC component removal filter that is connected to a subsequent stage of the integrator. Magnetic suppression control device.   The demagnetization correction amount calculation includes a level determination unit that determines the magnitude of the magnetic flux deviation amount, and the demagnetization correction amount to the voltage command value only when the magnetic flux deviation amount is equal to or greater than a predetermined threshold value. The bias magnetism suppression control device according to claim 1, further comprising: a changeover switch for adding   The demagnetization suppression control device according to claim 1, wherein the demagnetization correction amount calculation unit outputs a value obtained by multiplying the magnetic flux deviation amount by a gain as the demagnetization correction amount.   7. The demagnetization suppression amount according to claim 6, wherein the demagnetization correction amount calculation unit obtains the demagnetization correction amount using a power converter current of a phase in which demagnetization is detected in addition to the magnetic flux deviation amount. Control device.   2. The demagnetization suppression control device according to claim 1, further comprising an activation circuit that prevents the constant voltage control of the power converter from being utilized during the demagnetization suppression control.   2. The bias suppression control apparatus according to claim 1, further comprising a timer circuit that operates the bias suppression control for a period that is an integral multiple of the power cycle from the start of control.

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