JP2013021848A - Control device for power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform excellent power conversion between a power converter and a three-phase AC system by using vector control even when voltage in a power system is three-phase unbalanced because of a system accident and so on.SOLUTION: A control device for a power converter connected to a three-phase AC power system comprises: a reverse-phase coordinate conversion circuit calculating reverse-phase d-axis current and reverse-phase q-axis current by performing dq vector coordinate conversion on output current in a reverse-phase rotation direction of system voltage of the three-phase AC power system; a first current controller controlling command values of the reverse-phase d-axis current and the reverse-phase q-axis current by comparing the command values with the reverse-phase d-axis current and the reverse-phase q-axis current of the reverse-phase coordinate conversion circuit as feedback values; and a first oscillation component extraction circuit extracting a secondary oscillation component by positive-phase current included in the reverse-phase d-axis current and the reverse-phase q-axis current of the reverse-phase coordinate conversion circuit. The first current controller compares the current command value with the reverse-phase d-axis current and the reverse-phase q-axis current of the reverse-phase coordinate conversion circuit after excluding the extracted secondary oscillation component by the positive-phase current from the reverse-phase d-axis current and the reverse-phase q-axis current.

Description

  The present invention relates to a control device for a power converter that is connected to a three-phase AC power system and receives power from the three-phase AC power system, and in particular, power for controlling a reverse-phase current output to the three-phase AC power system. The present invention relates to a control device for a conversion device.

  In a three-phase AC system (hereinafter simply referred to as a power system) in a normal operation state, the negative phase voltage, which is a three-phase unbalanced voltage component, is sufficiently smaller than the positive phase voltage, which is a three-phase balanced voltage component. For this reason, a power conversion apparatus that performs vector control employs a control system that controls power by converting coordinates in the normal phase rotation direction. This is a vector control for the power conversion apparatus in a normal operation state. There was no hindrance.

  However, in the case of an unbalanced system fault such as a 1-wire ground fault or a 2-wire ground fault, negative phase voltage and negative phase current are largely included. In this case, if the previous control method is applied to coordinate-transform the negative phase voltage or negative phase current in the positive phase rotation direction, a secondary vibration component is generated. On the other hand, if integral control is applied to the current control system that controls the output current as a control device for the power converter, the control performance deteriorates, such as phase lag and steady deviation remaining due to secondary vibration components. End up.

  Therefore, for example, in Non-Patent Document 1, instead of vector control, the current command value including the positive phase current and the reverse phase current is inversely converted to a two-phase AC that is 90 ° out of phase, and the current control is performed on the two-phase AC signal. doing.

Kato, Ito, Aihara, Ikuta, “Self-excited reactive power compensator with flicker suppression function”, Hitachi review, Vol. 89, No. 2, 2007, p204-207

  However, as in Patent Document 1, when the AC signal is controlled as it is without using vector control, or when the controlled object vibrates even if vector control is applied, the integration control is applied. A phase delay occurs and it is difficult to make the steady deviation zero.

  In view of this, the present invention is to convert power between a power converter and a three-phase AC system using vector control even when the voltage of the power system is three-phase unbalanced due to, for example, a system failure. Objective.

  In order to achieve the above object, according to the present invention, in the control device for the power converter connected to the three-phase AC power system, the output current is expressed in the dq vector coordinates in the reverse phase rotation direction of the system voltage of the three-phase AC power system. A negative phase coordinate conversion circuit for obtaining a negative phase d-axis current and a negative phase q-axis current by conversion, and a negative phase d-axis current and a negative phase q-axis current of the negative phase coordinate conversion circuit are used as feedback values. A first current controller for comparing and controlling to a command value, a first vibration component extracted by a positive phase current included in the negative phase d-axis current and the negative phase q-axis current of the negative phase coordinate conversion circuit. A second vibration component extracted from the positive-phase current is excluded from the negative-phase d-axis current and the negative-phase q-axis current of the negative-phase coordinate transformation circuit, and the current is controlled by the first current controller. Compare with the command value.

  In order to achieve the above object, in the present invention, in a control device for a power converter connected to a three-phase AC power system, the output current is expressed in dq vector coordinates in the positive phase rotation direction of the system voltage of the three-phase AC power system. A positive phase coordinate conversion circuit for obtaining a positive phase d-axis current and a positive phase q-axis current by conversion, and a positive phase d-axis current and a positive phase q-axis current of the positive phase coordinate conversion circuit are used as feedback values. A second current controller that controls to a command value by comparison, a second vibration component that extracts a secondary vibration component due to a negative phase current included in the positive phase d-axis current and the positive phase q-axis current of the positive phase coordinate conversion circuit. A second vibration component extracting circuit that excludes the second-order vibration component due to the extracted negative-phase current from the positive-phase d-axis current and the positive-phase q-axis current of the positive-phase coordinate conversion circuit, and Compare with the command value.

  In order to achieve the above object, in the present invention, a reverse phase d-axis current and a reverse phase q-axis current are obtained by performing dq vector coordinate conversion of the output current in the reverse phase rotation direction of the system voltage of the three-phase AC power system. A negative phase current controller and a negative phase coordinate for controlling the command value of the phase coordinate conversion circuit, the negative phase d axis current and the negative phase q axis current of the negative phase coordinate conversion circuit as feedback values and comparing them with the command values of these currents. A first vibration component extraction circuit that extracts a secondary vibration component due to the positive phase current included in the negative phase d-axis current and the negative phase q-axis current of the conversion circuit, and reverses the secondary vibration component due to the extracted positive phase current A first addition unit that is excluded from the negative-phase d-axis current and negative-phase q-axis current of the phase coordinate conversion circuit and provided as a feedback value to the negative-phase current controller, the normal-phase rotation direction of the system voltage of the three-phase AC power system The output current is converted into dq vector coordinates to convert the positive phase d-axis current and the positive phase q Positive phase coordinate conversion circuit for obtaining current, and positive phase current controller for controlling the positive phase d-axis current and positive phase q-axis current of the positive phase coordinate conversion circuit as feedback values and comparing them with command values of these currents , A second vibration component extraction circuit for extracting a secondary vibration component due to the negative phase current included in the positive phase d-axis current and the positive phase q-axis current of the positive phase coordinate conversion circuit; And a second addition unit that excludes the vibration component from the positive phase d-axis current and the positive phase q-axis current of the positive phase coordinate conversion circuit and provides the positive phase current controller as a feedback value.

  Further, the first vibration component extraction circuit converts the positive phase d-axis current command value and the normal phase q-axis current command value, which are the command values of the second current controller, into dq vector coordinates twice in the reverse phase rotation direction. Circuit.

  In addition, the second vibration component extraction circuit converts the negative phase d-axis current command value and the negative phase q-axis current command value, which are the command values of the first current controller, into dq vector coordinates twice in the normal phase rotation direction. Circuit.

  The first vibration component extraction circuit also outputs a positive phase current amplitude extractor that extracts a positive phase current amplitude included in the output current, and a secondary that outputs a sine wave signal and a cosine wave signal having a frequency twice that of the system voltage. The phase of the sine wave signal and cosine wave signal is the sum of the system voltage phase of the three-phase AC power system and the power factor angle of the output current, and the output of the positive phase current amplitude extractor and the cosine wave. This is a circuit for outputting the product of the signal and the product of the output of the positive phase current amplitude extractor and the sine wave signal.

  The second vibration component extraction circuit also outputs a negative-phase current amplitude extractor that extracts the negative-phase current amplitude included in the output current, and a secondary that outputs a sine wave signal and a cosine wave signal having a frequency twice that of the system voltage. The phase of the sine wave signal and cosine wave signal is -2 times the system voltage phase and the difference between the power factor angles of the negative phase current and the product of the output of the positive phase current amplitude extractor and the cosine wave signal and This circuit outputs the product of the output of the positive phase current amplitude extractor and the sine wave signal.

  The positive phase current amplitude extractor converts the output current of the power converter into two phase currents Ia and Ib that are 90 ° out of phase with each other by a three phase two phase converter, and performs an FFT operation. Is decomposed into sine wave components Iare and Ibre and cosine wave components Iaim and Ibim having the same frequency f0 as the system voltage Vs of each of the two-phase currents Ia and Ib, and the sum of Iare and Ibim and the difference between Ibre and Iaim are input. As a result, the mean square calculation is performed by the mean square calculator, and the positive phase component amplitude of the output current is calculated.

  The negative phase current amplitude extractor converts the output current of the power conversion device into two-phase currents Ia and Ib that are 90 ° out of phase by a three-phase two-phase converter, and performs an FFT operation. Is decomposed into sine wave components Iare, Ibre and cosine wave components Iaim, Ibim having the same frequency f0 as the system voltage Vs of each of Ia, Ib, and the root mean square calculation using the difference between Ibim and Iare and the sum of Ibre and Iaim as inputs The root-mean-square calculation is performed by the detector, and only the negative phase component amplitude of the output current is calculated.

  In order to achieve the above object, in the present invention, in a control device for a power converter connected to a three-phase AC power system via a transformer, the system voltage of the three-phase AC power system is output in the reverse phase rotation direction. A negative phase coordinate conversion circuit for obtaining a negative phase d-axis current and a negative phase q-axis current by converting the current into a dq vector coordinate, and a negative phase d-axis current and a negative phase q-axis current of the negative phase coordinate conversion circuit as feedback values. Extraction of secondary vibration component due to the positive phase current included in the negative phase d-axis current and negative phase q-axis current of the negative phase coordinate conversion circuit, the negative phase current controller that controls to the command value compared with the current command value The first vibration component extracting circuit that removes the secondary vibration component due to the extracted normal phase current from the negative phase d-axis current and negative phase q-axis current of the negative phase coordinate conversion circuit, and is fed back to the negative phase current controller. 1st addition part given as a value, system voltage of three-phase AC power system Positive phase coordinate conversion circuit for obtaining positive phase d-axis current and positive phase q-axis current by converting dq vector coordinates of output current in the normal phase rotation direction, and positive phase d-axis current and positive phase q-axis current of positive phase coordinate conversion circuit Is a positive phase current controller that controls to a command value by comparing with the command value of these currents, and a value obtained by multiplying the positive phase d-axis current command value by the reactor value of the transformer on the positive phase q-axis current side A compensation circuit is provided that subtracts from the output of the positive phase current controller and adds the value obtained by multiplying the positive phase q-axis current command value by the reactor value of the transformer to the positive phase current controller output on the negative phase d-axis current side. The command value of the phase current controller is set to 0.

  The power converter of the present invention can control the positive phase current and the negative phase current with zero steady-state deviation even when the power system voltage is in a three-phase unbalanced state such as a one-wire ground fault or a two-wire ground fault. improves.

  In the embodiment of the present invention, when the power converter only needs to output the positive phase current, if the current command value of the reverse phase current output from the power converter is set to 0, the voltage of the power system is not three-phase. Even in a balanced state, the current flowing in each phase of the power converter can be balanced in three phases, so that the capacity of the apparatus can be reduced, and the apparatus can be reduced in size and loss.

  Further, according to the present embodiment, even when it is necessary to control the output negative phase current as in the case of the unbalance compensation device, the negative phase current and the positive phase current can be controlled independently.

The figure which shows the structure of the control apparatus of the power converter device of Example 1 of this invention. The figure which shows the structural example of the electric power grid | system including a power converter device. The figure which shows the structure of the control apparatus of the power converter device of Example 2 of this invention. The figure which shows one example of a negative phase current amplitude extractor. The figure which shows an example of a positive phase current amplitude extractor. The figure which shows the structure of the control apparatus of the power converter device of Example 3 of this invention.

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

  FIG. 2 shows a configuration example of a power system including a power conversion device.

  The power converter 1 of this embodiment includes a voltage-type inverter device (hereinafter simply referred to as an inverter device) 11 having a DC capacitor 111 and a self-extinguishing element 112 such as IGBT or GCT, and an output voltage of the inverter device 11. The control device 12 that outputs an output voltage command value Vcr for control, the DC voltage sensor 15 that measures the terminal voltage Vdc of the DC capacitor 111 of the inverter device 11, and the inverter device 11 and the three-phase AC power system 2 are linked. An interconnection transformer 14 having a leakage reactance component Xc, a current sensor 16 for measuring a current Ic output from the inverter device 11, an AC voltage sensor 17 for measuring a system voltage Vs of the three-phase AC power system 2, The self-extinguishing element 112 of the inverter device 11 is turned on in response to the output voltage command Vcr supplied from the control device 12. Configured with a PWM circuit 13 for generating the gate pulse GP to control off.

  In this embodiment, the current sensor 16 is installed on the three-phase AC power system 2 side (hereinafter referred to as the primary side) of the interconnection transformer 14, but the inverter device 11 side of the interconnection transformer 14. (Hereinafter referred to as the secondary side).

  Next, operation | movement of the power converter device 1 is demonstrated. The control device 12 of the power conversion device 1 receives from the inverter device 11 the terminal voltage Vdc of the DC capacitor 111, the system voltage Vs of the three-phase AC power system 2, and the current Ic output from the power conversion device 1, and inputs the inverter device. 11 outputs the command value Vcr of the output voltage Vc.

  The PWM circuit 13 outputs a gate pulse GP for controlling on / off of the self-extinguishing element 112 of the inverter device 11 based on the magnitude relationship between the output voltage command value Vcr and a carrier such as a triangular wave.

  The inverter device 11 converts the power with the three-phase AC power system 1 by outputting the output voltage Vc of the inverter device 11 to the interconnection transformer 14 based on the gate pulse GP output from the PWM circuit 13. .

  Next, the configuration of the control device 12 will be described. FIG. 1 is a diagram showing an outline of a control block of the control device 12 shown in FIG. Here, first, the basic configuration of vector control of the power conversion device 1 will be described, and then countermeasures against secondary vibration components will be described.

  The control device 12 shown in FIG. 1 can be considered by dividing the function to be implemented into four blocks. The first block is a phase detector A (phase detector 21) that detects the positive phase voltage phase θ of the system voltage from the system voltage Vs. The second block is a normal phase current calculation unit B, and the third block is a negative phase current calculation unit C. The fourth block is a current synthesizer D. Among these, the positive phase current calculation unit B and the negative phase current calculation unit C are handled in different amounts, but basically have the same circuit configuration.

  The phase detector 21 of the first block A detects the positive phase voltage phase θ of the system voltage Vs by a known PLL (Phase Locked Loop) circuit, DFT (Discrete Fourier Transform) circuit, or the like.

  In the positive phase current calculation unit B, first, the three-phase two-phase converter 51 receives the three-phase output current Ic of the power conversion device 1 and converts it into two-phase currents Iα and Iβ that are 90 degrees out of phase. . Further, the positive phase coordinate converter 22 performs known dq coordinate conversion using the positive phase voltage phase θ obtained by the phase detector 21 and the two-phase currents Iα and Iβ obtained by the three-phase two-phase converter 51. , D-axis current Id1 (hereinafter simply referred to as positive-phase d-axis current Id1) coordinate-converted in the normal phase rotation direction and q-axis current Iq1 (hereinafter simply referred to as positive-phase q-axis current Iq1) converted in the positive-phase rotation direction. Calculated). Here, the number “1” given to the positive phase d-axis current Id1 and the positive phase q-axis current Iq1 means that it corresponds to the positive phase. This positive phase current calculation unit B is configured as a positive phase dq vector coordinate system in which coordinates are converted in a direction synchronized with the positive phase voltage of the power system, and will be simply referred to as a positive phase coordinate system hereinafter.

  Similarly, in the negative phase current calculation unit C, first, in the three-phase two-phase converter 51, the three-phase output current Ic of the power conversion device 1 is input, and the two-phase currents Iα and Iβ that are 90 degrees out of phase are input. Convert to Further, in the negative phase coordinate converter 23, the negative phase voltage phase (−θ) rotating in the opposite direction to the positive phase voltage phase θ obtained by the phase detector 21, and the two phase obtained by the three phase two phase converter 51. A known dq coordinate transformation is performed using the currents Iα and Iβ, and a d-axis current Id2 (hereinafter simply referred to as a negative-phase d-axis current Id2) coordinate-transformed in the reverse-phase rotation direction and a q-transformed coordinate in the reverse-phase rotation direction An axial current Iq2 (hereinafter simply referred to as a reverse phase q-axis current Iq2) is calculated. Here, the number “2” attached to the negative phase d-axis current Id2 and the negative phase q-axis current Iq2 means that the phase is the negative phase. The negative phase current calculation unit C is configured as a negative phase dq vector coordinate system obtained by coordinate conversion in a direction synchronized with the negative phase voltage of the power system, and will be simply referred to as a negative phase coordinate system hereinafter.

  The dq coordinate transformation, the three-phase two-phase transformation, the dq inverse coordinate transformation and the two-phase three-phase transformation performed by the positive phase current computing unit B or the negative phase current computing unit C are well known. Detailed description of is omitted.

  The positive-phase d-axis current Id1, the positive-phase q-axis current Iq1, and the negative-phase d-axis current Id2 and the negative-phase q-axis current Iq2 obtained as described above are obtained when the three-phase AC system is in an equilibrium state. Derived as a flow rate. These DC amounts are feedback signals for vector control, and vector control command values (positive phase d-axis current command value Id1r, positive phase q-axis current command value Iq1r, and further negative phase d-axis current command value Id2r). , A negative phase q-axis current command value Iq2r) is provided to constitute a current control system.

  The current controller 28 (28a, 28b, 28c, 28d) of the positive phase current calculation unit B and the negative phase current calculation unit C performs vector control on the subtractor AD (AD1, AD2, AD3, AD4) provided in the preceding stage. A feedback signal and a command value are introduced, and current control is performed based on the difference.

  The current controller 28a is a current controller for the positive phase d-axis current Id1, the current controller 28b is a current controller for the positive phase q-axis current Iq1, and the current controller 28c is a negative phase d-axis current Id2. The current controller 28d and the current controller 28d are current controllers for the anti-phase q-axis current Iq2.

  The outputs of these current controllers 28 are Vd1, Vq1, Vd2, and Vq2, respectively. Among these, Vd1 and Vq1 mean the positive phase d-axis correction voltage (Vd1) and the positive phase q-axis correction voltage (Vq1) for controlling the output current Ic of the power converter 1 to the current command values Id1r and Iq1r. ). Also, what Vd2 and Vq2 mean is a negative phase d-axis correction voltage (Vd2) and a negative phase q-axis correction voltage (Vq2) for controlling the output current Ic of the power converter 1 to the current command values Id2r and Iq2r. It is.

  The correction voltages Vd1, Vq1, Vd2, and Vq2 are used for subsequent control after eliminating interference due to the product of the current command value and the leakage reactance component Xc of the transformer 14. For example, the multiplier 32a calculates Id1r × Xc obtained by multiplying the positive phase d-axis current command value Id1r by the leakage reactance component Xc of the transformer, and subtracts it from the correction voltage Vq1 in the compensation circuit CP2. The multiplier 32b calculates Iq1r × Xc obtained by multiplying the positive-phase q-axis current command value Iq1r and the leakage reactance component Xc of the transformer, and adds it to the correction voltage Vd1 in the compensation circuit CP1.

  Similarly, the multiplier 32c calculates Id2r × Xc obtained by multiplying the negative phase d-axis current command value Id2r by the leakage reactance component Xc of the transformer, and subtracts it from the correction voltage Vq2 in the compensation circuit CP4. The multiplier 32d calculates Iq2r × Xc obtained by multiplying the anti-phase q-axis current command value Iq2r by the leakage reactance component Xc of the transformer, and adds it to the correction voltage Vd2 in the compensation circuit CP3.

  The vector control command values (positive phase d-axis current command value Id1r, positive phase q-axis current command value Iq1r, negative phase d-axis current command value Id2r, negative phase q-axis current command value Iq2r given to the current controller 28. ) Is made to control the DC voltage Vdc constant or to keep the AC voltage constant. Since the method for creating the command value is not directly related to the present invention, a detailed description thereof is omitted, but in general, it is a signal created by the host control system. In other words, if the power converter is applied to motor control, a command value for current control is created in a host control system related to motor speed or torque control. Further, when voltage control is performed by the power conversion device, the voltage control system is an upper control system.

  Next, in the normal phase inverse coordinate converter 29, the signal of the compensation circuit CP1 (addition value of Iq1r × Xc and the correction voltage Vd1) and the signal of the compensation circuit CP2 (subtraction value of Id1r × Xc and the correction voltage Vq1) , The system voltage phase θ is input, and known inverse dq coordinate transformation is performed to inversely transform the currents into two-phase currents Iα and Iβ having a phase difference of 90 degrees. Subsequently, the two-phase / three-phase converter 52 restores the three-phase component and outputs the output voltage command value Vc1r of the power conversion device 1 in the positive phase coordinate system.

  Similarly, in the inverse phase inverse coordinate converter 30, a subtraction value between the signal of the compensation circuit CP3 (added value of Iq2r × Xc and the correction voltage Vd2) and the signal of the compensation circuit CP4 (Id2r × Xc and the correction voltage Vq2). ) And the system voltage reverse phase (−θ), and the known reverse dq coordinate conversion is performed to reversely convert the current into two-phase currents Iα and Iβ that are 90 degrees different in phase. Subsequently, the two-phase / three-phase converter 52 restores the three-phase component and outputs the output voltage command value Vc2r of the power conversion device 1 in the reverse phase coordinate system.

  Finally, processing in the current synthesizer D of the fourth block is performed. Here, the phase rotator 31 receives the system voltage Vs and rotates the phase so that the voltage phase on the primary side of the interconnection transformer 14 in FIG. 1 becomes the voltage phase on the secondary side. For example, if the primary side of the interconnection transformer 14 is a star winding and the secondary side is a Δ winding, the phase may be advanced by 30 degrees. However, each winding of the interconnection transformer is not limited to the above. Then, the output of the phase rotator 31 and the added value of Vc1r and Vc2r are output to the PWM circuit 12 as the output voltage command value Vcr of the inverter device 11.

  A control device of a power conversion device that executes vector control is generally configured as shown in FIG. In the present invention, a fluctuation component twice the system voltage frequency in the normal phase coordinate system due to the negative phase current (hereinafter simply referred to as the negative phase secondary current) is reproduced. In addition, a fluctuation component twice the system voltage frequency in the negative phase coordinate system due to the positive phase current (hereinafter simply referred to as the positive phase secondary current) is reproduced. Further, the reproduced negative phase secondary current is subtracted from the positive phase current, and the reproduced positive phase secondary current is subtracted from the negative phase current.

  Specifically, in the event of an unbalanced system fault such as a 1-wire ground fault or a 2-wire ground fault, the outputs (positive phase d-axis current Id1, positive phase q-axis current Iq1) of the normal phase coordinate converter 22 or the negative phase coordinate converter 23 , Secondary vibration components included in the anti-phase d-axis current Id2 and anti-phase q-axis current Iq2) are obtained and excluded by the subtraction circuit ad (ad1, ad2, ad3, ad4).

  In reproducing the negative-phase secondary current and the positive-phase secondary current, in the embodiment of FIG. 1, the current command values (the positive-phase d-axis current command value Id1r, the positive-phase q-axis current command value Iq1r, and the negative-phase d The secondary vibration component is reproduced from the shaft current command value Id2r and the negative phase q-axis current command value Iq2r).

  This reproduction process is performed in the positive phase current calculation unit B as follows. First, when the output current Ic includes a reverse phase current, a vibration component having a frequency twice that of the system voltage due to the negative phase current is superimposed on the positive phase d axis current Id1 and the positive phase q axis current Iq1.

  In the processing of the normal phase current calculation unit B of the present invention, the d-axis and q-axis negative phase current command values Id2r and Iq2r to be output to the inverter device 11 are low-passes that simulate the control response delay of the current controllers 28c and 28d. Input to the filters LPF 53a and 53b. Then, the normal phase coordinate converter 22 is configured in two stages, thereby performing coordinate conversion twice in the normal phase direction. Thus, a d-axis current Id12 and a q-axis current Iq12 (hereinafter simply referred to as a negative-phase reproduction d-axis current Id12 and a negative-phase reproduction q-axis current Iq12) that reproduce vibration components having a frequency twice that of the system voltage due to the negative-phase current. ) The vibration component is removed by subtracting the negative phase reproduction d-axis current Id12 from the positive phase d axis current Id1 in the subtractor ad1 and subtracting the negative phase reproduction q axis current Iq12 from the positive phase q axis current Iq1 in the subtractor ad2. Can do.

  In short, the concept of the positive phase current calculation unit B is that the secondary vibration component included in the positive phase current is reproduced from the negative phase current command value. This reproduction is performed for each dq axis.

  In addition, this reproduction process is performed in the negative phase current calculation unit C as follows. First, when the output current Ic includes a reverse phase current, a vibration component having a frequency twice that of the system voltage due to the negative phase current is superimposed on the negative phase d axis current Id2 and the negative phase q axis current Iq2.

  In the processing of the negative phase current calculation unit C of the present invention, the d axis and q axis positive phase current command values Id1r and Iq1r to be output to the inverter device 11 are low-passes that simulate the control response delay of the current controllers 28a and 28b. Input to the filters LPF 53c and 53d. Then, the anti-phase coordinate converter 23 is configured in two stages, thereby converting the coordinates in the anti-phase direction twice. Thus, a d-axis current Id22 and a q-axis current Iq22 (hereinafter simply referred to as a positive-phase reproduction d-axis current Id22 and a positive-phase reproduction q-axis current Iq22) that reproduce a vibration component having a frequency twice that of the system voltage due to the reverse-phase current. ) The subtractor ad3 subtracts the positive phase reproduction d-axis current Id22 from the negative phase d axis current Id2, and the subtractor ad4 subtracts the positive phase reproduction q axis current Iq22 from the negative phase q axis current Iq2. Can do.

  In short, the idea of the negative phase current calculation unit C is that the secondary vibration component included in the negative phase current is reproduced from the normal phase current command value. This reproduction is performed for each dq axis.

  As a result, the calculation by the current controller 28 can be not affected by the secondary vibration component.

  By adopting the configuration of the present embodiment, it is possible to remove the secondary vibration component due to the antiphase component in the normal phase coordinate system and the secondary vibration component due to the positive phase component in the antiphase coordinate system. Even if it is necessary to control the negative-phase current output to, the negative-phase current and the positive-phase current can be controlled independently.

  Further, since integral control can be applied to the current controllers 28a to 28d, the steady deviation can be set to 0, and the control performance can be improved.

  If the power converter needs to output only the positive phase current, the current command value of the negative phase current output from the power converter can be set to 0, even if the power system voltage is three-phase unbalanced. Since the current flowing through each phase of the device can be balanced in three phases, the device capacity can be reduced, and the device can be downsized and reduced in loss.

  In the description of FIG. 1, the inputs of the multipliers 32a and 32b are the command values Id1r and Iq1r here, but they may be signals obtained by subtracting Id12 and iq12 from Id1 and iq1, respectively. Similarly, the inputs of the multipliers 32c and 32d are the command values Id2ref and Iq2ref, but they may be signals obtained by subtracting Id22 and iq22 from Id2 and iq2, respectively.

  FIG. 3 is a diagram illustrating an outline of a control block of the control device 12 of the power conversion device 1 according to the second embodiment.

  Hereinafter, the configuration and operation of the second embodiment will be described, but the description of the same or corresponding parts as those of the first embodiment will be omitted, and only different parts will be described.

  The second embodiment is different from the first embodiment in a method of estimating a negative phase current in the normal phase coordinate system and a vibration component twice the system voltage due to the positive phase current in the negative phase coordinate system. Other circuit portions are the same as those in the first embodiment.

  The concept of secondary current estimation in the second embodiment will be described using equations. First, if the two-phase current obtained by three-phase to two-phase conversion of the three-phase output current Ic is iα, iβ, and the positive phase voltage phase of the system voltage is θ, the d-axis obtained by converting the output current Ic by dq coordinates in the reverse phase rotation direction The negative-phase current id2 and the q-axis negative-phase current iq2 can be expressed by the equation (1) using the two-phase currents iα and iβ.

またここで，二相電流ｉαとｉβは、正相電流振幅Ｉ１，力率角θ_０（以後単に正相力率角）の正相電流が含まれており、（２）式で示すことができる。

Here, the two-phase currents iα and iβ include a positive-phase current having a positive-phase current amplitude I1 and a power factor angle θ ₀ (hereinafter simply referred to as a positive-phase power factor angle). it can.

（１）（２）式の関係から，ｄ軸逆相電流ｉｄ２とｑ軸逆相電流ｉｑ２は、正相電流を用いて（３）式で表すことができる。

(1) From the relationship of the formula (2), the d-axis reverse phase current id2 and the q-axis reverse phase current iq2 can be expressed by the formula (3) using a positive phase current.

（３）式は、ｄ軸逆相電流ｉｄ２とｑ軸逆相電流ｉｑ２が，その大きさはＩ１つまり正相電流の振幅であり，位相は正相電圧位相θの２倍と正相力率角θ_０の和である信号として求められることを示している。

In the equation (3), the d-axis negative phase current id2 and the q-axis negative phase current iq2 are I1, that is, the amplitude of the positive phase current, and the phase is twice the positive phase voltage phase θ and the positive phase power factor. It is shown that it is obtained as a signal that is the sum of the angle θ ₀ .

  Similarly, a d-axis positive phase current id1 and a q-axis positive phase current iq1 obtained by converting the output current Ic into dq coordinates in the positive phase rotation direction can be expressed by the equation (4) using the two-phase currents iα and iβ. .

また二相電流ｉα、ｉβは、逆相電流振幅Ｉ２，力率角θ_１（以後単に逆相力率角）の逆相電流が含まれており、（５）式で示すことができる。

Further, the two-phase currents iα and iβ include a negative-phase current having a negative-phase current amplitude I2 and a power factor angle θ ₁ (hereinafter simply referred to as a negative-phase power factor angle), and can be expressed by Expression (5).

このとき（４）式から，ｄ軸正相電流ｉｄ１、ｑ軸正相電流ｉｑ１は、（６）式で表すことができる。

At this time, from the equation (4), the d-axis positive phase current id1 and the q-axis positive phase current iq1 can be expressed by the equation (6).

（６）式は，ｄ軸正相電流ｉｄ１、ｑ軸正相電流ｉｑ１が、その大きさはＩ２，つまり逆相電流の振幅であり，位相は逆相電圧位相θの２倍と逆相力率角θ_１の差である信号として求められることを示している。

In the equation (6), the d-axis positive phase current id1 and the q-axis positive phase current iq1 are I2, that is, the amplitude of the negative phase current, and the phase is twice the negative phase voltage phase θ and the negative phase force. It shows that it is obtained as a signal that is the difference of the rate angle θ ₁ .

  Based on the above relationship, the amplitude and vibration components of the positive and negative phase currents can be reproduced in order to reproduce the negative phase current in the normal phase coordinate system and the oscillation component twice the system voltage due to the positive phase current in the negative phase coordinate system. It can be seen that it is only necessary to create a sine wave and cosine wave signal synchronized with the.

Based on the above analysis, in the second embodiment of the present invention, the negative phase current amplitude extractor for extracting the negative phase current amplitude I2, which is the amplitude of only the negative phase component of the output current Ic, into the positive phase current calculation unit B. 60, the negative phase current amplitude I2 output from the negative phase current amplitude extractor 60, the negative phase voltage phase θ of the system voltage, and the negative phase power factor angle θ ₁ are input, and by the negative phase current in the normal phase coordinate system. And an anti-phase secondary oscillator 63 that outputs signals Id12 and Iq12 reproducing the secondary oscillating current. In the anti-phase secondary oscillator 61, equations (7) and (8) are calculated using these inputs.

[Equation 7]
Id12 = I ₂ × cos (2θ + θ ₁ ) (7)

[Equation 8]
Iq12 = I ₂ × sin (2θ + θ ₁ ) (8)
Based on the above analysis, in the second embodiment of the present invention, the positive phase current amplitude extractor for extracting the positive phase current amplitude I1, which is the amplitude of only the positive phase component of the output current Ic, into the negative phase current calculation unit C. 62, the positive-phase current amplitude I1 output from the positive-phase current amplitude extractor 62, the positive-phase voltage phase θ of the system voltage, and the positive-phase power factor angle θ ₀ are input. And a positive phase secondary oscillator 63 that outputs signals Id22 and Iq22 reproducing the next oscillating current. The positive-phase secondary oscillator 63 calculates equations (9) and (10) using these inputs.

[Equation 9]
Id22 = I ₁ × cos (2θ + θ ₁ ) (9)

[Equation 10]
Iq22 = I ₁ × sin (2θ + θ ₁ ) (10)
In addition, in the second embodiment of the present invention, the outputs of the positive-phase secondary oscillator 61 and the negative-phase secondary oscillator 63 are respectively converted into the d-axis positive phase current Id1, the q-axis positive phase current Iq1, and the d-axis negative phase current Id2. , The vibration component can be removed by subtracting from the q-axis reverse phase current Iq2.

  FIG. 4 shows an example of the negative phase current amplitude extractor 60. In the negative phase current amplitude extractor 60, first, a three-phase two-phase conversion calculation is performed by the three-phase two-phase conversion calculator 41, and the two-phase current Ia having a phase difference of 90 ° from the output current Ic, which is a three-phase current. , Ib.

  Next, the FFT computing unit 42 that performs a well-known FFT (Fast Fourier Transform) operation is decomposed into sine wave components Iare and Ibre of the same frequency f0 as the system voltage Vs of each of Ia and Ib, and cosine wave components Iaim and Ibim. To do.

  Next, the root mean square operation is performed by the mean square computing unit 43 using the difference between Iare and Ibim and the sum of Ibre and Iaim as inputs. Thereby, the negative phase current amplitude I2 which is an amplitude of only the negative phase component of the output current can be calculated.

  FIG. 5 is an example of the positive phase current amplitude extractor 62. The positive phase current amplitude extractor 62 performs a well-known three-phase two-phase conversion calculation by the three-phase two-phase conversion calculator 41, and the two-phase currents that are 90 ° out of phase with the output current Ic that is a three-phase current. Convert to Ia and Ib.

  Next, the FFT calculator 42 that performs a well-known FFT calculation is decomposed into sine wave components Iare and Ibre and cosine wave components Iaim and Ibim having the same frequency f0 as the system voltage Vs of each of Ia and Ib.

  Next, a square average calculation is performed by the square average calculator 43 using the sum of Iare and Ibim and the difference between Ibre and Iaim as inputs, thereby calculating a positive phase current amplitude I1 that is an amplitude of only the positive phase component of the output current. can do.

  As described above, by adopting the configuration of this embodiment, it is possible to remove the secondary vibration component due to the antiphase component in the normal phase coordinate system and the secondary vibration component due to the positive phase component in the antiphase coordinate system. Even when it is necessary to control the output negative phase current as described above, the negative phase current and the positive phase current can be controlled independently.

  In addition, when the power converter only needs to output the positive phase current, if the current command value of the negative phase current output from the power converter is set to 0, the power can be output even when the voltage of the power system is three-phase unbalanced. Since the current flowing through each phase of the converter can be balanced in three phases, the capacity of the device can be reduced, and the size and loss of the device can be reduced.

  In addition, the well-known integral control is applied to the current controllers 28a to 28d, so that the steady-state deviation can be set to 0, and the control performance can be improved.

  FIG. 6 is a diagram schematically illustrating a control block of the control device 12 of the power conversion device 1 according to the third embodiment of the present invention. Since Example 3 in FIG. 6 basically follows the concept of Example 2 in FIG. 3, the description of the same or corresponding parts as in Example 2 is omitted, and only different parts are described below. To do.

  The control block of the control device 12 of the power conversion device 1 shown in FIG. 6 omits the negative phase current amplitude extractor 60 and the negative phase secondary oscillator 61 from the control block shown in FIG. The difference is that the command value Id2r is set to 0 and the q-axis reverse phase current command value Iq2r is set to 0.

  Next, only the differences from the second embodiment will be described regarding the operation and effects of the control device 12. First, in the third embodiment of FIG. 6, the positive phase current calculation unit B is not provided with the negative phase current amplitude extractor 60 and the negative phase secondary oscillator 61. For this reason, Id1 and Iq1 include a secondary vibration component due to a reverse phase current. In addition, this circuit configuration cannot be removed.

  On the other hand, in the negative phase current calculation unit C, since the d-axis negative phase current command value Id2r and the q-axis negative phase current command value Iq2r are set to 0, the negative phase current included in the output current Ic of the power converter is It can be suppressed after the control response time of the current controllers 28a and 28b. For this reason, the secondary vibration component due to the reverse phase current included in Id1 and Iq1 is reduced.

  As a result, the control performance of the power converter 1 is not significantly affected, and the negative-phase current amplitude extractor 60 and the negative-phase secondary oscillator 61 can be reduced, so that the calculation load of the controller 12 can be reduced.

  The present invention can be applied to a power conversion device using a self-extinguishing element such as an IGBT or a GCT, particularly a power conversion device having a function capable of controlling a reverse phase current.

1: Power conversion device 2: Three-phase AC system 11: Inverter device 12: Control device 13: PWM circuit 14: Converter for interconnection 15: DC voltage sensor 16: Current sensor 17: AC voltage sensor 21: Phase detector 22 : Normal phase coordinate converter 23: reverse phase coordinate converters 28a to 28d: current controller 29: normal phase reverse coordinate converter 30: reverse phase reverse coordinate converter 31: phase rotator 32a to d: multiplier 41: three Phase-to-phase converter 42: FFT calculator 43: root mean square calculator 51: three-phase two-phase converter 52: two-phase three-phase converter 60: negative phase current amplitude extractor 61: negative phase secondary oscillator 62: positive Phase current amplitude extractor 63: positive phase secondary oscillator

Claims (10)

In the control device of the power converter connected to the three-phase AC power system,
A negative phase coordinate conversion circuit for obtaining a negative phase d-axis current and a negative phase q-axis current by performing a dq vector coordinate conversion of the output current in the negative phase rotation direction of the system voltage of the three-phase AC power system, and the negative phase coordinate conversion circuit A negative phase d-axis current and a negative phase d-axis current of the negative phase coordinate conversion circuit, wherein the negative phase d-axis current and the negative phase q-axis current are feedback values, and are compared with the command values of these currents to control the command values. And a first vibration component extraction circuit that extracts a secondary vibration component due to the positive phase current included in the negative phase q-axis current, and the second phase vibration component due to the extracted positive phase current is converted into the negative phase coordinate conversion circuit. A control device for a power converter, wherein the first current controller compares the current command value with a current command value, excluding the negative phase d-axis current and negative phase q-axis current. In the control device of the power converter connected to the three-phase AC power system,
A positive phase coordinate conversion circuit that obtains a positive phase d-axis current and a positive phase q-axis current by performing dq vector coordinate conversion of the output current in the positive phase rotation direction of the system voltage of the three-phase AC power system, and the positive phase coordinate conversion circuit The positive-phase d-axis current and the positive-phase d-axis current of the positive-phase coordinate conversion circuit are the second current controller that controls the positive-phase d-axis current and the positive-phase q-axis current as feedback values and compares them with the command values. And a second vibration component extraction circuit for extracting a secondary vibration component due to the negative phase current included in the normal phase q-axis current, and the positive phase coordinate conversion circuit for extracting the secondary vibration component due to the extracted negative phase current. A control device for a power converter, wherein the second current controller compares the current command value with a current command value by excluding the positive phase d-axis current and positive phase q-axis current. In the control device of the power converter connected to the three-phase AC power system,
A negative phase coordinate conversion circuit for obtaining a negative phase d-axis current and a negative phase q-axis current by performing a dq vector coordinate conversion of the output current in the negative phase rotation direction of the system voltage of the three-phase AC power system, and the negative phase coordinate conversion circuit The negative-phase d-axis current and the negative-phase q-axis current are used as feedback values, and compared with the command values of these currents to control to the command value, A first vibration component extraction circuit for extracting a secondary vibration component due to a positive phase current included in the negative phase q-axis current, and a second phase vibration component due to the extracted positive phase current as a negative phase d of the negative phase coordinate conversion circuit. A first adder that is excluded from an axial current and a negative-phase q-axis current and provided as a feedback value to the negative-phase current controller, and the output current is dq in the positive-phase rotation direction of the system voltage of the three-phase AC power system Obtains positive phase d-axis current and positive phase q-axis current by vector coordinate transformation A phase coordinate conversion circuit, a positive phase d-axis current and a positive phase q-axis current of the positive phase coordinate conversion circuit as feedback values, and a positive phase current controller for controlling to a command value by comparing with a command value of these currents; A second vibration component extraction circuit for extracting a secondary vibration component due to the negative phase current included in the positive phase d-axis current and the positive phase q-axis current of the phase coordinate conversion circuit; a secondary vibration component due to the extracted negative phase current; Including a second addition unit that excludes the positive phase d-axis current and the positive phase q-axis current from the positive phase coordinate conversion circuit and gives the positive phase current controller as a feedback value. Control device for the device. In the control apparatus of the power converter device according to claim 3,
The first vibration component extraction circuit is a circuit that performs dq vector coordinate conversion twice in the reverse phase rotation direction of the positive phase d-axis current command value and the positive phase q-axis current command value, which are command values of the second current controller. A control device for a power conversion device. In the control apparatus of the power converter device according to claim 3,
The second vibration component extraction circuit is a circuit that converts the negative phase d-axis current command value and the negative phase q-axis current command value, which are command values of the first current controller, twice in the normal phase rotation direction by dq vector coordinates. A control device for a power conversion device. In the control apparatus of the power converter device according to claim 3,
The first vibration component extraction circuit extracts a positive phase current amplitude included in the output current and a secondary that outputs a sine wave signal and a cosine wave signal having a frequency twice the system voltage. And a phase of the sine wave signal and the cosine wave signal is a sum of a system voltage phase of the three-phase AC power system and a power factor angle of the output current, and the positive phase current amplitude extractor And a circuit for outputting the product of the output of the cosine wave signal and the product of the output of the positive phase current amplitude extractor and the sine wave signal. In the control apparatus of the power converter device according to claim 3,
The second vibration component extraction circuit extracts a negative phase current amplitude included in the output current and a secondary phase that outputs a sine wave signal and a cosine wave signal having a frequency twice the system voltage. The phase of the sine wave signal and the cosine wave signal is a difference between -2 times the system voltage phase and the power factor angle of the negative current, and the output of the positive phase current amplitude extractor and the A control device for a power conversion device, wherein the control device is a circuit that outputs a product of a cosine wave signal and a product of the output of the positive phase current amplitude extractor and the sine wave signal. In the control apparatus of the power converter according to claim 6,
The positive-phase current amplitude extractor converts an output current of the power conversion device into two-phase currents Ia and Ib that are shifted from each other by 90 ° by a three-phase two-phase converter, and performs an FFT operation. Is decomposed into sine wave components Iare, Ibre and cosine wave components Iaim, Ibim having the same frequency f0 as the system voltage Vs of each of the two-phase currents Ia, Ib, and the difference between the sum of Iare and Ibim and Ibre and Iaim is calculated. A control apparatus for a power converter, wherein a mean square calculation is performed as an input by a mean square calculator to calculate a positive phase component amplitude of an output current. In the control apparatus of the power converter device according to claim 7,
The reverse-phase current amplitude extractor converts an output current of the power converter into two-phase currents Ia and Ib that are 90 ° out of phase with each other by a three-phase two-phase converter, and performs an FFT operation. Is decomposed into sine wave components Iare, Ibre and cosine wave components Iaim, Ibim having the same frequency f0 as the system voltage Vs of each of Ia, Ib, and the root mean square with the difference between Ibim and Iare and the sum of Ibre and Iaim as inputs A control apparatus for a power converter, wherein a mean square calculation is performed by an arithmetic unit to calculate only the negative phase component amplitude of the output current. In a control device for a power converter connected to a three-phase AC power system via a transformer,
A negative phase coordinate conversion circuit for obtaining a negative phase d-axis current and a negative phase q-axis current by performing a dq vector coordinate conversion of the output current in the negative phase rotation direction of the system voltage of the three-phase AC power system, and the negative phase coordinate conversion circuit The negative-phase d-axis current and the negative-phase q-axis current are used as feedback values, and compared with the command values of these currents to control to the command value, A first vibration component extraction circuit for extracting a secondary vibration component due to a positive phase current included in the negative phase q-axis current, and a second phase vibration component due to the extracted positive phase current as a negative phase d of the negative phase coordinate conversion circuit. A first addition unit that is excluded from the axial current and the negative-phase q-axis current and gives the negative-phase current controller as a feedback value;
A positive phase coordinate conversion circuit that obtains a positive phase d-axis current and a positive phase q-axis current by performing dq vector coordinate conversion of the output current in the positive phase rotation direction of the system voltage of the three-phase AC power system, and the positive phase coordinate conversion circuit The positive-phase d-axis current and the positive-phase q-axis current are used as feedback values, and are compared with the command values of these currents to control the command values. The value multiplied by the reactor value is subtracted from the output of the positive phase current controller on the positive phase q-axis current side, and the value obtained by multiplying the positive phase q-axis current command value by the reactor value of the transformer is calculated on the negative phase d-axis current side. A control device for a power converter, comprising a compensation circuit for adding to an output of a positive phase current controller, and setting a command value of the negative phase current controller to 0.

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