JP2006230047A - Control device of power converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a control device of a power converter that further surely suppresses an overcurrent in a transitional deviated magnetization state. <P>SOLUTION: In the control device 10 of an inverter 3 that gives and receives power to and from an AC system bus bar 1 via a transformer 2, an operation circuit 31 that calculates the correction amount of a voltage that suppresses deviated magnetization on the basis of a part that causes the overcurrent of an exciting current in the deviated magnetization state of the transformer 2 is added to the control device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention particularly relates to a control device for a power conversion device that suppresses magnetic demagnetization.

  Conventionally, a configuration of a power converter as shown in FIG. 15 has been disclosed.

  The DC capacitor 9 stores a DC voltage.

  The power converter, for example, the inverter 3 is composed of a power semiconductor such as a GTO thyristor, and converts a DC voltage stored in the DC capacitor 9 into an AC voltage.

  The inverter transformer 2 supplies the AC voltage converted by the inverter 3 to the power system, for example, the three-phase AC bus 1.

  The reference circuit 61 generates reference values such as a predetermined system voltage and load current of the three-phase AC bus 1 and outputs the reference values to the current control circuit 62.

  The current control circuit 62 compares the reference value output from the reference circuit 61 with the system voltage and load current of the three-phase AC system bus 1 output from the current detector 11 and generates an output voltage reference for the inverter 3. And output to the adder 7.

  The current detector 11 detects the system voltage and the load current of the three-phase AC bus 1 and outputs them to the subtractor 13.

  The current detector 12 measures the secondary current of the inverter transformer 2 and outputs it to the subtractor 13.

  The subtractor 13 obtains a difference between the current detector 11 and the current detector 12 and outputs the difference to the comparator 14 and the filter circuit 17.

  The comparator 14 determines whether the bias current exceeds a predetermined value based on the output from the subtractor 13, and outputs a signal to the pulse generator 15.

  When the imbalance between the positive polarity portion and the negative polarity portion of the output voltage of the inverter transformer 2 is larger than a predetermined reference based on the output of the comparator 14, the pulse generator 15 has a predetermined positive or negative value. A pulse having a constant amplitude and a constant duration is output to the integrator 16.

  The integrator 16 integrates the output of the pulse generator 15 to convert it into a DC signal, delays it, and outputs it to the adder 18.

  The filter circuit 17 extracts the steep / transient component of the biased magnetic component from the output of the subtractor 13 and outputs it to the adder 18.

  The adder 18 adds the output of the integrator 16 and the output of the filter circuit 17.

  The adder 7 adds the output of the current control circuit 62 and the output of the adder 18.

  The comparator 14, the pulse generator 15, and the integrator 16 gently compensate for steady demagnetization, and the filter circuit 17 compensates for transient demagnetization.

  The carrier triangular wave reference 81 generates a signal serving as a reference for generating a pulse for controlling the power semiconductor element of the inverter 3.

  The comparator 84 compares the output voltage reference of the inverter 3 with the reference carrier triangular wave.

  The logic circuit 82 controls the power semiconductor element of the inverter 3 based on the comparison result of the comparator 84.

  The pulse amplifier 83 amplifies the control pulse generated by the logic circuit 82 and drives the inverter 3.

  For steady-state bias, the comparator 14 has an imbalance between the positive peak value and the negative peak value of the deviation current between the secondary current and the primary current of the transformer 2 larger than a predetermined value. Detect that. The pulse generator 15 receives the output of the comparator 14, generates a pulse having a constant interval width at a predetermined constant level so as to balance the positive and negative voltage time products and correct the bias. The output of the inverter 3 is controlled slowly.

On the other hand, with respect to transient biasing, the filter circuit 17 controls the output of the inverter 3 by detecting only a steep biasing current component (see, for example, Patent Document 1).
Patent No. 2829237

  Originally, the purpose of suppressing transient bias is to control the overcurrent of the power converter caused by the bias saturation of the transformer in an emergency evacuation manner and avoid the situation where the overcurrent of the power converter is stopped. is there.

  In the control device of the power conversion device of Patent Document 1, for transient biasing, only a steep biasing current component is detected from the deviation current, and biasing is suppressed based on this.

  However, detection of only a steeply biased magnetic current component does not react when the overcurrent continues gently, and is insufficient to suppress a transient overcurrent.

  Therefore, an object of the present invention is to provide a control device for a power converter that can more reliably suppress an overcurrent in a transient biased state.

  The invention corresponding to claim 1 for achieving the above object is a power conversion device comprising a power converter connected to a power system via a transformer and converting direct current to alternating current or alternating current to alternating current. A control means for controlling the power converter based on a command value; a primary current acquisition means for acquiring a primary current value flowing between the transformer and the power converter; and between the transformer and the power system. A secondary current acquisition means for acquiring a secondary current value flowing through the input, and input values acquired by the primary current acquisition means and the secondary current acquisition means, and a correction target for determining a difference between these acquisition values as a correction target value When the absolute value of the correction target value is equal to or greater than a predetermined value, the control unit determines a first correction amount for correcting the waveform of the electrical quantity on the AC side of the power converter based on the correction target value. First correction means for supplying to the means; It is the structure provided with.

  According to the present invention, it is possible to perform an operation with a low possibility of stopping due to an overcurrent in a transient biased state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, matters common to the embodiments will be described. The power converter of the present invention is the same as the conventional example of FIG. Specifically, as shown in FIGS. 1, 4, 6, 8, 10, 11, 12, 13, and 14, the basic configuration of the power system is a power system such as an AC system bus 1. On the other hand, it is connected via a transformer 2 and converts direct current into alternating current or alternating current into alternating current. In each embodiment, an inverter 3 is shown as an example.

  The inverter 3 is connected to a DC capacitor 4 and is controlled by a control means described later in accordance with this voltage to generate an AC voltage. The generated AC voltage is stepped up or stepped down through the transformer 2, and this voltage is applied to the AC system bus 1 to transfer power between the inverter 3 and the AC system bus 1.

  The waveform data shown in FIGS. 2, 5, 7, and 9 are assumed waveforms for explaining the functions of the circuits constituting the apparatus according to each embodiment. For simplicity, the primary current of the transformer 2 is shown in each figure. These waveforms and the waveform of the secondary current do not take into account the effect of the bias suppression control, and all the gains are represented as the same magnification.

(Configuration of the first embodiment)
The power converter control device 10 (hereinafter, simply referred to as “control device 10”) mainly includes a control unit, a correction target determination unit, a first correction unit, and a second correction unit.

  The control means includes, for example, a voltage command generator 6, an adder 7, and a PWM controller 5.

  The correction target determining means includes primary current acquisition means such as a primary current detector 12, secondary current acquisition means such as a secondary current detector 11, and a subtractor 13.

  The first correction means includes an arithmetic circuit 31 and a gain 32, for example.

  The second correction means includes low-frequency extraction means such as a low-pass filter 21 and a gain 22.

  The control device 10 controls the inverter 3 and adjusts the output AC power in order to exchange power with the AC system bus 1. The inverter 3 is also controlled when suppressing the bias of the transformer 2.

  The secondary current detector 11 detects the measured value of the secondary current flowing between the transformer 2 on the secondary side of the transformer 2 and the AC system bus 1 (hereinafter referred to as “secondary current value”). And input to the control device 10.

  A measured value of the primary current flowing between the inverter 3 which is the primary side of the transformer 2 and the transformer 2 (hereinafter referred to as “primary current value”) is detected by the primary current detector 12 and is sent to the control device 10. Entered.

  The primary current value detected by the primary current detector 12 and the secondary current value detected by the secondary current detector 11 are input to the subtractor 13.

  The subtractor 13 detects the excitation current as the correction target value by subtracting the input secondary current value and primary current value in consideration of the turns ratio of the transformer 2, and the low-pass filter 21 and the arithmetic circuit 31. Output to.

  The low-pass filter 21 detects a direct current component from the input excitation current, converts it to an appropriate value by the gain 22, and outputs it to the adder 18 as a steady bias suppression command.

  When the absolute value of the input excitation current value (hereinafter referred to as “excitation current value”) exceeds a preset value, the arithmetic circuit 31 sets the excitation current value to an appropriate value by the gain 32. And output to the adder 18 as a transient demagnetization suppression command. On the other hand, when a current value exceeding the set value is not detected, the arithmetic circuit 31 outputs 0 to the adder 18.

  The voltage command generator 6 generates a voltage command that serves as a reference for the voltage output by the inverter 3 during normal operation, and outputs the voltage command to the adder 7.

  The adder 18 adds the steady demagnetization suppression command input from the low pass filter 21 via the gain 22 and the transient demagnetization suppression command input from the arithmetic circuit 31 via the gain 32, It outputs to the adder 7 as a demagnetization suppression command.

  The adder 7 adds the voltage command created by the voltage command creating unit 6 and the demagnetization suppression command input from the adder 18 and outputs the sum to the PWM controller 5.

  The PWM controller 5 controls the voltage of the DC capacitor 4 by the pulse width modulation method based on the command input from the adder 7 and generates an AC voltage from the inverter 3.

  Here, the function of the control device 10 will be described with reference to FIG. 2A and 2B show waveforms output by main circuits of the present embodiment, where FIG. 2A shows the secondary current waveform detected by the secondary current detector 11 and FIG. 2B shows the primary current detected by the primary current detector 12. It is assumed that a current waveform is detected. In addition, a dotted line illustrated in (c) represents a set value line.

  Current waveforms (a) and (b) are input to the subtracter 13, and the excitation current shown in (c) is output to the arithmetic circuit 31.

  An excitation current (c) is input to the low-pass filter 21, and only a low frequency component is extracted here, and a steady demagnetization suppression command shown in (d) is output to the adder 18.

  An excitation current (c) is input to the arithmetic circuit 31 and a transient demagnetization suppression command shown in (e) is output to the adder 18.

  In the adder 18, the steady-state demagnetization suppression command (d) and the transient demagnetization suppression command (e) are added, and this added value is the demagnetization suppression command shown in (f). 7 is output.

(Operation and effect of the first embodiment)
FIG. 3 shows the correlation between the state of the magnetic flux density B inside the transformer and the excitation current I flowing inside the transformer, which is a phenomenon seen in the transformer 2.

  When the magnetic flux density B rises and the transformer 2 reaches the saturation region of the saturation curve, the excitation current I increases rapidly. In this case, the current value becomes larger than the steady excitation current value.

  The control device 10 sets a current value before and after the saturation curve as a set value, and outputs a transient bias suppression command when a current exceeding the set value is detected. It can be carried out.

  Further, as the output of the arithmetic circuit 31, an exciting current component exceeding the set value is output as it is, and based on this, a transient demagnetization suppression command is created. Therefore, the control device 10 effectively suppresses demagnetization. It can be performed.

  Therefore, if it is the control apparatus 10 of this embodiment, the steady biasing of the transformer 2 can be suppressed, and especially the control which suppresses a transient biasing efficiently and effectively can be performed.

(Configuration of Second Embodiment)
FIG. 4 is a block configuration diagram for explaining the present embodiment.

  The control device 10 of the present embodiment is the same as that of FIG. 1 except that the arithmetic circuit 31 included in the control device 10 of the embodiment shown in FIG.

  When the absolute value of the input excitation current value exceeds a preset set value, the arithmetic circuit 36 appropriately calculates a value obtained by subtracting a set value having the same sign as the excitation current value from the excitation current value by the gain 32. And is output to the adder 18 as a transient demagnetization suppression command.

  Here, the function of the control device 10 will be described with reference to FIG. FIG. 5 illustrates the waveforms output by the main circuits of the present embodiment, assuming that the waveform of the secondary current shown in (a) and the waveform of the primary current shown in (b) are detected. . In addition, a dotted line illustrated in (c) represents a set value line.

  The arithmetic circuit 36 receives the excitation current (c) detected by the subtractor 13 and outputs a transient demagnetization suppression command shown in (e) to the adder 18 via the gain 32.

  The adder 18 receives the steady bias suppression command (d) and the transient bias suppression command (e), and outputs the bias suppression command shown in (f) to the adder 7.

(Operation / Effect of Second Embodiment)
In the present embodiment, in order to create a transient demagnetization suppression command based on a value obtained by subtracting a set value from the input excitation current value, control for suppressing increase / decrease in the correction amount of the current for suppressing demagnetization is performed. It can be carried out. Therefore, when the excitation current exceeds the set value, the correction amount suddenly increases, or when the excitation current decreases, the correction amount suddenly decreases, so that the control device 10 operates more than necessary. Or overcorrection less than necessary.

  Therefore, with the control device 10 of the present embodiment, even when the exciting current value repeatedly increases and decreases near the set value, the power converter is efficiently controlled to suppress a transient biased state. Control can be performed.

(Configuration of Third Embodiment)
FIG. 6 is a block diagram for explaining the present embodiment.

  In the second embodiment shown in FIG. 4, the control device 10 of this embodiment is provided with an adder 35 between the gain 32 and the adder 18, and a high-frequency component extracting means such as a high-pass filter is provided at the output terminal of the subtractor 13. 4 except that one end of 33 is connected and the other end of the high-pass filter 33 is connected to the other input terminal of the adder 35 via a gain 34.

  In this case, the configuration of the third correction unit includes, for example, a high-pass filter 33, a gain 34, and an adder 35.

  The subtractor 13 outputs an excitation current to the arithmetic circuit 36 and the high pass filter 33.

  The high-pass filter 33 detects a transient component from the input excitation current, converts it to an appropriate value by the gain 34, and outputs it to the adder 35 as a calculation element of a transient demagnetization suppression command.

  The arithmetic circuit 36 performs an operation based on the input excitation current, and outputs it to the adder 35 through the gain 32 as an arithmetic element of a transient demagnetization suppression command.

  The adder 35 adds the outputs input from the arithmetic circuit 36 and the high-pass filter 33 and outputs the result to the adder 18 as a transient demagnetization suppression command.

  Here, the function of the control device 10 will be described with reference to FIG. FIG. 7 illustrates the waveforms output by the main circuits of this embodiment, assuming that the waveform of the secondary current shown in (a) and the waveform of the primary current shown in (b) are detected. .

  The high-pass filter 33 receives the excitation current (c) detected by the subtractor 13 and outputs the calculation element of the transient demagnetization suppression command shown in (d) to the adder 35 via the gain 34.

(Operations and effects of the third embodiment)
In the present embodiment, when the excitation current changes suddenly by providing the high-pass filter 33, a transient bias suppression command is input before the input excitation current value exceeds the set value of the arithmetic circuit 36. Can be output.

  Therefore, if it is the control apparatus 10 of this embodiment, the correction amount can be ensured from the very early stage until the transformer 2 reaches saturation, and the control for suppressing the transient biased state can be performed.

(Configuration of Fourth Embodiment)
FIG. 8 is a block diagram for explaining the present embodiment.

  In the third embodiment shown in FIG. 6, the control device 10 according to the present embodiment connects the input side of the high-pass filter 33 to the output side of the arithmetic circuit 36 without connecting to the output terminal of the subtractor 13. Except for this, it is the same as FIG.

  In this case, the configuration of the first correction means includes an arithmetic circuit 36, a gain 32, an adder 35, a high-pass filter 33, and a gain 34.

  The high-pass filter 33 detects a transient component from the excitation current input via the arithmetic circuit 36 and outputs the transient component to the adder 35 via the gain 34 as an arithmetic element for a transient demagnetization suppression command.

  Here, the function of the control device 10 will be described with reference to FIG. FIG. 9 illustrates the waveforms output by the main circuits of the present embodiment, assuming that the waveform of the secondary current shown in (a) and the waveform of the primary current shown in (b) are detected. .

  The high-pass filter 33 receives the excitation current (c) from the subtractor 13 through the arithmetic circuit 36, and passes through the gain 34 to the adder 35 as an arithmetic element of the transient demagnetization suppression command shown in (d). Output.

(Operation / Effect of Fourth Embodiment)
In the present embodiment, the input excitation current is input to the high-pass filter 33 via the arithmetic circuit 36, so that the transient bias suppression command is output only when the excitation current exceeds the set value.

  Therefore, only when the degree of transient magnetization is high, the correction amount can be secured from an early stage when the transformer 2 reaches saturation, and efficient control for suppressing the transient magnetization state can be performed. .

(Configuration of Fifth Embodiment)
FIG. 10 is a block diagram for explaining the present embodiment.

  The power system using this embodiment does not require the secondary current detector 11.

  The current acquisition unit includes, for example, a primary current detector 12.

  The control device 10 of this embodiment is the same as that of FIG. 4 except that the secondary current detector 11 and the subtractor 13 are not provided in the second embodiment shown in FIG.

  The primary current value detected by the primary current detector 12 is input to the low-pass filter 21 and the arithmetic circuit 36.

  The low-pass filter 21 detects a direct current component from the input primary current, converts it to an appropriate value by the gain 22, and outputs it to the adder 18 as a steady bias suppression command.

  The arithmetic circuit 36 takes the difference between the input primary current value and the set value having the same sign as the primary current value, converts the value into an appropriate value by the gain 32, and adds it as a transient demagnetization suppression command. Output to the device 18.

  The subtracter 8 subtracts the voltage command generated by the voltage command generator 6 and the bias suppression command input from the adder 18 and outputs the result to the PWM controller 5.

(Operation and effect of the fifth embodiment)
When the voltage command by the control operation does not need to change sharply, the control device 10 is almost the same as the control by detecting the excitation current from the primary current and the secondary current, even by the control by detecting only the primary current. The same effect is produced.

  Further, when the set value of the arithmetic circuit 36 is set to a value obtained by adding the maximum value of the normal operating current and the maximum value of the normal exciting current in a vector manner, the output of the circuit 36 is other than 0 because the overcurrent is This is only the case for large currents. With this setting, the control device 10 can perform control to suppress a large current when the transformer 2 is saturated.

  Therefore, if it is the control apparatus 10 of this embodiment, it can be used also in the electric power grid | system in which the current detector 11 is not installed. Moreover, since it is not necessary to take in measured values from the current detector 11, the control device 10 can be produced at low cost and can be installed at low cost.

  In the present embodiment, the control is performed by detecting only the primary current, but the control may be performed by detecting only the secondary current.

(Configuration of the sixth embodiment)
FIG. 11 is a block diagram for explaining the present embodiment.

  In the embodiment shown in FIG. 4, magnetic bias information detection means, for example, a voltage sensor 41, a voltage sensor 42, and a magnetic bias detector 43 are added.

  In the second embodiment shown in FIG. 4, the control device 10 of the present embodiment is configured such that the input of the low-pass filter 21 is a voltage sensor 41 that detects the potential on the primary side of the transformer 2 and the secondary side of the transformer 2. 4 is the same as FIG. 4 except that the bias information detected by the bias detector 43 is input based on the voltage sensor 42 that detects the potential.

  The voltage sensor 41 measures the potential on the secondary side of the transformer 2 and outputs the measured potential to the bias magnet detector 43.

  The voltage sensor 42 measures the potential on the primary side of the transformer 2 and outputs the measured potential to the magnetic bias detector 43.

  The magnetism detector 43 detects the magnetism information of the transformer 2 by taking the deviation of the secondary voltage of the primary voltage from the measured value of the voltage sensor 42 and the measured value of the voltage sensor 41 in consideration of the transformation ratio. And output to the low-pass filter 21.

  The low-pass filter 21 detects a direct current component from the input bias information, converts it to an appropriate value by the gain 22, and outputs it to the adder 18 as a steady bias suppression command.

(Operation and effect of the sixth embodiment)
In the present embodiment, since the demagnetization information is detected from the primary voltage and the secondary voltage of the transformer 2, the direct current component of the voltage that causes the demagnetization of the magnetic flux can be directly detected.

  Therefore, if it is the control apparatus 10 of this embodiment, before the transformer 2 is demagnetized and saturated, the DC component by demagnetization can be detected and suppressed.

(Configuration of the seventh embodiment)
FIG. 12 is a block configuration diagram for explaining the present embodiment.

  4 is the same as FIG. 4 except that, for example, a magnetic flux sensor 44 is installed in the vicinity of the transformer 2 and the detected magnetic flux is input to the low-pass filter 21 as the bias information detecting means. is there.

  The magnetic flux sensor 44 detects the magnetic bias information of the transformer 2 by measuring the magnetic flux of the transformer 2 and outputs it to the low-pass filter 21.

  The low-pass filter 21 detects a direct current component from the input bias information, converts it to an appropriate value by the gain 22, and outputs it to the adder 18 as a steady bias suppression command.

(Operation and effect of the seventh embodiment)
In the present embodiment, since the magnetic flux information is detected by the magnetic flux sensor 44, the magnetic flux state of the transformer 2 can be directly detected.

  Therefore, if it is the control apparatus 10 of this embodiment, before the transformer 2 is demagnetized and saturated, the DC component by demagnetization can be detected and suppressed.

(Configuration of Eighth Embodiment)
FIG. 13 is a block diagram for explaining the present embodiment.

  The control device 10 of the present embodiment is the same as the second embodiment shown in FIG. 4 except for the following points. Instead of the voltage command generator 6, a current command generator 51 and a current controller 54 are provided, and between the current command generator 51 and the current controller 54, limiting means such as a limiter 52 and current correction means are provided. For example, it is the structure which added the subtractor 53 and the electric current command preparation means, for example, the electric current command preparation device 51.

  The secondary current detector 11 outputs the detected secondary current value to the subtracter 13 and the subtractor 53.

  The current command generator 51 generates a current command that serves as a reference for the current output by the inverter 3 during normal operation, and outputs the current command to the subtractor 53 via the limiter 52.

  The arithmetic circuit 36 performs a calculation based on the input excitation current value, and outputs the calculated value to the limiter 52 when the calculated value exceeds the set value.

  The limiter 52 suppresses the current command based on the calculated calculation value of the calculation circuit 36. For example, when the current command is 2000 A, the current command is suppressed to 1600 A of 80% when the calculated value is 400 A, and the current command is suppressed to 0 A of 0% when the calculated value is 2000 A or more.

  The subtractor 53 subtracts the input secondary current value from the input current command, and outputs this to the current controller 54 as a current command.

  The current controller 54 converts it into a voltage command based on the input current command, and outputs this to the adder 7.

  The adder 7 adds the input voltage command and the demagnetization suppression command input from the adder 18 and outputs the result to the PWM controller 5.

(Operation / Effect of Eighth Embodiment)
Hereinafter, a specific example of this embodiment will be described.

  Here, for the sake of simplicity, the turns ratio of the transformer 2 is assumed to be 1: 1, and a steady demagnetization suppression command is not considered.

  It is assumed that the current command generator 51 outputs a current command so that the secondary current is 2000A. Under normal conditions, current control of the current controller 54 works, and 2000 A flows as the secondary current in accordance with the current command of the current command generator 51. The primary current also flows 2000A. Therefore, the two current detectors 11 and 12 both detect 2000 A, and the output of the subtractor 13 is 0, so that the demagnetization suppression command is also 0.

  Here, it is assumed that the transformer 2 is saturated and the primary current flows 2500A. The primary current detector 12 detects 2500A, and the subtractor 13 outputs -500A. Therefore, since the demagnetization suppression command takes a negative value, the current controller 54 attempts to suppress the current by controlling the output voltage of the inverter 3 to be low. When the voltage of the inverter 3 is reduced, the secondary voltage of the transformer 2 is also reduced, and the secondary current is less than 2000A. However, since the current command remains 2000 A, the current command due to the current deviation in the subtractor 53 takes a positive value, and the current controller 54 controls the output voltage of the inverter 3 to be high, thereby reducing the current. Try to increase. As a result, the control based on the demagnetization suppression command and the control based on the current command are contradictory controls.

  What is important when the transformer 2 is saturated is to demagnetize so that the power converter 3 does not stop overcurrent. Controlling the current according to the current command is the purpose of control. As a priority, it becomes lower.

  In the present embodiment, by providing the limiter 52, when the output for suppressing the demagnetization is detected by the arithmetic circuit 36, the demagnetization suppression may be prioritized by reducing the current value of the current command by the limiter 52. it can.

  Therefore, in the control device 10 according to the present embodiment, the inverter 3 that controls the output of current gives priority to the effect of suppressing the demagnetization in the demagnetization state leading to the overcurrent stop and effectively outputs the output current. Can be controlled.

  The relationship between the calculated value of the calculation circuit 36 and the amount of suppression of the current command by the limiter 52 is not limited to this embodiment, and other calculation methods and numerical values may be used. Further, the limiter 52 may always suppress the current command at a constant rate when a calculation value is sent from the calculation circuit 36. For example, if the calculated value is 500 A or more, the current command may always be suppressed to 80%.

(Configuration of the ninth embodiment)
FIG. 14 is a block diagram for explaining the present embodiment.

  The control device 10 of the present embodiment includes the second correction means, for example, an adder 18, a low-pass filter 21, and a gain 22 in the control device 10 of the second embodiment shown in FIG. It is the same as FIG.

  The output of the arithmetic circuit 36 is directly output to the adder 7 as a demagnetization suppression command.

(Operation and effect of the ninth embodiment)
This embodiment has an effect equivalent to that of the second embodiment with respect to the transient biased state of the transformer 2.

  Therefore, the control device 10 can be produced at a low cost, and is particularly versatile and expandable, such as when used in combination with another device or device that suppresses the steady biased state of the transformer 2. It can be produced as a high device.

(Modification)
The present invention is not limited to the embodiment described above, and can be implemented with various modifications.

  (1) Circuits, devices, and the like constituting the control device 10 are not limited to hardware. It may be realized by a program having an equivalent function, or may have a configuration in which hardware and software are mixed. Since software and hardware can be selected according to the function of the device, etc., it can be selected so that the function of the individual device can be exhibited more effectively, or can be selected to reduce the cost of the individual device, etc. . Therefore, an optimal configuration can be selected from various variations depending on the situation.

  (2) The excitation current of the transformer 2 is often 1% or less of the rating. However, the excitation current may be designed to be large so that the amount of magnetization of the transformer 2 can be easily detected.

  (3) When the excitation current is less than or equal to the set value, the operation of the present invention is not limited to the output from the arithmetic circuit 31 or the arithmetic circuit 36 with the correction amount set to zero. You may output the signal which locks the output of a demagnetization suppression command with respect to the arbitrary circuits which comprise the control apparatus 10. FIG. Further, the means for outputting the signal to be locked may be provided with another circuit, or a function may be added by software. In this case, since individual functions can be simplified, the expandability and maintainability of the control device 10 can be improved.

  (4) Although three types of adder 7, adder 18, and adder 35 are used as the type of adder, these arbitrary adders may be combined into one or more adders. In this case, circuit design and software design can be performed according to various purposes such as the size and expandability of the apparatus.

  (5) The power conversion device to be controlled in the present invention is not limited to an inverter that obtains AC power from DC power, but may be a cycloconverter or a matrix converter that directly converts AC power from AC power.

  (6) The voltage command generator 6 and the current command generator 51 may not be provided as devices constituting the control device 10. A command value serving as a reference may be taken from an external device, or a signal based on the frequency of the voltage output from the power converter may be taken and control may be performed based on this. Or it is good also as a control apparatus which extracts the electric quantity used as a reference | standard from the electric quantity of an electric power grid | system, and correct | amends a demagnetization suppression.

  (7) In each embodiment, the primary current acquisition unit, the secondary current acquisition unit, and the current acquisition unit include the primary current detector 12 or the secondary current detector 11. The device may not include means for measuring the amount of electricity flowing through the power system. You may operate by acquiring the measured value measured with the external equipment.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram for demonstrating the structure of the apparatus regarding the 1st Embodiment of this invention. The wave form diagram for demonstrating the function of the main circuits of the apparatus regarding 1st Embodiment. The correlation diagram for demonstrating the exciting current of all the embodiments. The block diagram for demonstrating the structure of the apparatus regarding 2nd Embodiment. The wave form diagram for demonstrating the function of the main circuits of the apparatus regarding 2nd Embodiment. The block diagram for demonstrating the structure of the apparatus regarding 3rd Embodiment. The wave form diagram for demonstrating the function of the main circuits of the apparatus regarding 3rd Embodiment. The block diagram for demonstrating the structure of the apparatus regarding 4th Embodiment. The wave form diagram for demonstrating the function of the main circuits of the apparatus regarding 4th Embodiment. The block diagram for demonstrating the structure of the apparatus regarding 5th Embodiment. The block diagram for demonstrating the structure of the apparatus regarding 6th Embodiment. The block diagram for demonstrating the structure of the apparatus regarding 7th Embodiment. The block diagram for demonstrating the structure of the apparatus regarding 8th Embodiment. The block diagram for demonstrating the structure of the apparatus regarding 9th Embodiment. The block diagram for demonstrating the structure of the apparatus regarding conventional embodiment.

Explanation of symbols

1 ... AC system bus, 2 ... Transformer, 3 ... Inverter, 4 ... DC capacitor,
5 ... PWM controller, 6 ... Voltage command generator, 7 ... Adder, 10 ... Control device,
11 ... secondary current detector, 12 ... primary current detector, 13 ... subtractor, 18 ... adder,
21: low-pass filter, 31: arithmetic circuit, 36: arithmetic circuit.

Claims (10)

In a power conversion device including a power converter that is connected to a power system via a transformer and converts direct current to alternating current or alternating current to alternating current,
Control means for controlling the power converter based on a command value;
Primary current acquisition means for acquiring a primary current value flowing between the transformer and the power converter;
Secondary current acquisition means for acquiring a secondary current value flowing between the transformer and the power system;
Correction target determination means for inputting the acquired values of the primary current acquisition means and the secondary current acquisition means and determining a difference between these acquired values as a correction target value;
When the absolute value of the correction target value is greater than or equal to a certain value, a first correction amount for correcting the waveform of the electric quantity on the AC side of the power converter is supplied to the control means based on the correction target value. A control device for a power converter, comprising: a first correction unit. In a power conversion device including a power converter that is connected to a power system via a transformer and converts direct current to alternating current or alternating current to alternating current,
Control means for controlling the power converter based on a command value;
Primary current acquisition means for acquiring a primary current value flowing between the transformer and the power converter;
Secondary current acquisition means for acquiring a secondary current value flowing between the transformer and the power system;
Correction target determination means for inputting the acquired values of the primary current acquisition means and the secondary current acquisition means and determining a difference between these acquired values as a correction target value;
When the absolute value of the correction target value is greater than or equal to a certain value, the electric power on the AC side of the power converter is determined based on the difference between the correction target value and the constant value that has the same sign as the correction target value. And a first correction unit that supplies a first correction amount for correcting the waveform of the amount to the control unit. The first correction means includes
The control device for a power converter according to claim 1, further comprising a high-frequency component extracting unit that extracts a high-frequency component. Bias information detecting means for detecting bias information relating to the bias state of the transformer;
Low frequency component extraction means for extracting low frequency components;
Second correction means for inputting the bias information to the low frequency component extraction means and supplying a second correction amount for correcting the waveform on the AC side of the power converter to the control means based on the output. The control device for the power conversion device according to any one of claims 1 to 3, wherein The control apparatus for a power converter according to claim 4, wherein the magnetic bias information detection unit detects the magnetic bias information based on the correction target value. Primary voltage acquisition means for acquiring a primary voltage value applied between the transformer and the power converter;
Secondary voltage acquisition means for acquiring a secondary voltage value applied between the transformer and the power system;
The bias information detecting means includes
The control of the power converter according to claim 4, wherein the acquired values of the primary voltage acquisition unit and the secondary voltage acquisition unit are input, and the bias information is detected based on the acquired values. apparatus. The control apparatus for a power converter according to claim 4, wherein the magnetic bias information detection unit detects the magnetic bias information using a magnetic flux sensor. High-frequency component extraction means for extracting high-frequency components;
The correction target value is input to the high-frequency component extraction means, and based on the output, a third correction amount for correcting the waveform of the electric quantity on the AC side of the power converter is supplied to the control means. The control device for a power converter according to any one of claims 1 to 3, or 4 to 7, further comprising a correction unit. Current command creating means for creating a current command serving as a reference for the secondary current value;
Limiting means for limiting the upper limit of the absolute value of the current command based on the first correction amount;
And a current correction unit that inputs a measurement value of the secondary current acquisition unit and the current command and supplies a current correction amount for correcting the waveform of the secondary current to the control unit based on these values. The control apparatus of the power converter device of any one of Claim 1 to 8. In a power conversion device including a power converter that is connected to a power system via a transformer and converts direct current to alternating current or alternating current to alternating current,
Control means for controlling the power converter based on a command value;
Current acquisition means for acquiring any one current value of a current value flowing between the transformer and the power converter and a current value flowing between the transformer and the power system;
When the absolute value of the acquired value of the current acquisition unit is equal to or greater than a predetermined value, the control unit has a first correction amount for correcting the waveform of the electric quantity on the AC side of the power converter based on the acquired value. And a first correction means for supplying the control device.

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