JP2011217574A - Wind power generation system, and device and method for controlling rotating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the stabilization of output of a rotating machine by eliminating the complicated calculation element and control element.SOLUTION: In a wind power generating system, a power generation output of an AC generator 2 driven by a windmill 3 is converted into a DC power by a generator-side inverter 13, this DC power is converted to an AC power by a system-side inverter according to a frequency/voltage of a linkage power supply, and a current of the inverter is controlled by a current control part 12. A target value of output control of the AC generator is set in an active power commanding device 31 as an active power command value, and a current command calculation part 10A converts the set active power command value to an actual active current command value by an output voltage of the inverter. Or, the target value of output control of the generator is set to the active current command value and a reactive current command value, and current control of the output of the generator is made by these current command values.

Description

  The present invention relates to a control device and a control method for a rotating machine such as a wind power generation system and a wind turbine AC generator, and more particularly to an apparatus and a method for controlling the output of a rotating machine by current control.

  In the wind power generation system, in order to supply the generated power of the AC generator driven by the windmill to the distribution network in conjunction with the commercial power source, it is necessary to be able to generate power at a constant frequency / constant voltage synchronized with the commercial power frequency. . However, since the rotational energy of the wind turbine that drives the generator frequently and greatly fluctuates, the power generation frequency / power generation voltage cannot be made constant by connecting the wind turbine directly to the generator or by a transmission gear. Therefore, there is a power conversion method in which the generator output is once converted into direct current, and this direct current power is controlled to a frequency / voltage that can be connected to a commercial power source by an inverter (see, for example, Patent Document 1 and Patent Document 2).

  FIG. 4 shows an apparatus configuration diagram of a conventional wind power generation system. This control device may be operated based on a speed command or operated based on a torque command, and is configured to be able to switch between speed control and torque control.

  The speed commander 1 generates a speed command given to the control device from the outside or created inside the control device. The generator 2 for windmills is comprised with an induction machine or a permanent magnet synchronous machine, and is driven by the windmill (propeller) 3 couple | bonded with the axis | shaft, and generates electric power.

  The position / speed detector 4 is attached to the generator 2 to detect the position / speed of the rotor, and may be an ordinary pulse encoder, an encoder that outputs an analog signal, or a resolver. The phase detector 5 calculates the magnetic flux phase of the generator 2 from the output of the position / speed detector 4. In addition, when the generator 2 is an induction machine, there is no this phase detection part. The speed detection calculation unit 6 calculates the speed detection value of the generator 2 from the phase difference obtained from the phase detection unit 5 per unit time.

  Normally, the speed controller 7 uses the speed command set by the speed commander 1 and the speed detection value from the speed detection calculation unit 6 as a comparison input, and obtains a torque command value by, for example, a proportional integration (PI) calculation result. This torque command value constitutes an automatic control system so that there is no deviation between the speed command and the speed detection value. The torque limiter 8 limits the limit value so that the torque command does not become abnormally large.

  The torque command device 9 outputs a torque command value given to the control device from the outside or created inside the control device. The current command calculation unit 10 selects the output of the torque limiter 8 when the control device operates based on the speed command, and selects the output of the torque command device 9 when the control device operates based on the torque command. It converts into the voltage command value according to these torque command values. The current command calculation unit 10 is normally configured with two components of an excitation current command value and a torque current command value so as to be applicable to vector control. The switch 11 switches the torque command value input of the voltage command value calculation unit, and when applied to the wind power generation system, the current command calculation unit 10 is switched to the output of the torque command unit 9.

  The current controller 12 compares the current command value from the current command calculation unit 10 with the detected current of the current detector 14 that detects the generated current to be supplied from the generator 2 to the generator-side inverter 13 and matches the two. Outputs the current command value for The PWM converter 15 converts the pulse voltage into a PWM voltage waveform corresponding to the voltage command value of the current controller 12 and generates AC power generated in the generator 2 by PWM control of each semiconductor switching device of the generator-side inverter 13. Is converted to direct current. In this conversion, the inverter output voltage detected by the voltage detector 16 is matched with the voltage command value.

  The system-side inverter 17 uses the DC output of the generator-side inverter 13 as a power source, and converts the power into an AC output whose voltage, frequency, and phase are controlled to the grid-side power. The input filter 18 removes a noise component from the output of the system side inverter 17, and the interconnection breaker 19 connects and cuts off the AC output through the input filter 18 to the electric power system to be connected.

  In the wind power generation system as described above, the wind turbine generator 2 and the wind turbine (propeller) 3 are becoming larger with the recent increase in generated power (for example, the size of the generator reaches several meters in diameter). . With this increase in size, it has become difficult mechanically and structurally to install the speed detector 4 (usually an encoder or resolver used in an industrial AC motor), and the speed detector 4 has been replaced. It is desired to control the generator by speed detection.

  As an implementation method, there is also an apparatus that uses a control method (sensorless control) for estimating the phase / speed of the generator 2 based on the current detection value of the current detector 14 and the voltage output from the inverter 13. FIG. 5 shows an apparatus configuration diagram in this case. 4 is different from FIG. 4 in that a phase estimation calculation unit 21 and a speed estimation calculation unit 22 are provided in place of the position / speed detection circuit elements 4 to 6 shown in FIG.

  The phase estimation calculation unit 21 estimates the current phase (rotor rotation angle) of the generator 2 from the current detection value of the current detector 14 and the current command value of the current controller 12. This estimated phase is used as a reference phase in vector control in the current controller 12. The speed estimation calculation unit 22 estimates a speed by performing a calculation such as differentiation of the estimated phase of the phase estimation calculation unit 21 and is used as a speed detection value to the speed controller 7.

  Such a control method based on phase / speed estimation can be used in any case, such as when the rotating machine is an induction motor or a permanent magnet synchronous motor.

FIG. 6A shows a more detailed block configuration diagram of the current command calculation unit to the rotating machine in FIG. 5, and FIG. 6B shows a vector diagram. The current command calculation unit 10 considers the current vector control of the output of the inverter 13 by the power converter 20 (a combination of the inverter 13 and the PWM converter 15), and the rotation coordinates synchronized with the rotation of the generator 2. The d-axis and q-axis current command values (reactive current command value, effective current command value) id ^* and iq ^* on (orthogonal dq axes) are given to the PI calculation unit 12A of the current controller 12. The PI operation unit 12A receives the command values id ^* and iq ^* and the detected values id and iq, and obtains a voltage command value for the dq axis by proportionally integrating (PI) the respective deviations. The two-phase / three-phase coordinate conversion unit 12B is a coordinate converter from the rotating coordinate system (two phases) to the fixed coordinate system (three phases), and converts the two-phase dq-axis voltage command value into the reference phase θ (FIG. 6). Then, the three-phase voltage command values V _U ^* , V _V ^* , and V _W ^* synchronized with the estimated value θ ^) are converted into voltage command values to the PWM converter 15 included in the power converter 20. .

The three-phase / two-phase coordinate conversion unit 12C is a coordinate conversion unit from the fixed coordinate system (three phases) to the rotating coordinate system (two phases), and the three-phase currents I _U , I _V , I _W is converted into a dq-axis two-phase current and used as an input to the PI calculation unit 12A. Similarly, the three-phase / two-phase coordinate conversion unit 12D is a coordinate conversion unit from the fixed coordinate system (three phases) to the rotating coordinate system (two phases), and the voltage command value V _U ^* , V _V ^* and V _W ^* are converted into a two-phase voltage on the dq axis. At the time of conversion by these coordinate conversion units 12C and 12D, a reference phase θ (estimated phase θ ^) is input.

  The phase estimation calculation unit 21 obtains an estimated value θ ^ of the rotor rotational position (phase) of the generator 2 from the two-phase current and voltage signals corresponding to the output of the generator 2 converted by the coordinate conversion units 12C and 12D.

Here, the relationship between the rotating coordinate system and the fixed coordinate system is shown in FIG. The relationship between the fixed coordinate system and the rotating coordinate system is linked by the phase difference between the axes of the fixed coordinate system and the rotating coordinate system.
FIG. 6B shows that there is a phase θ difference between the U axis and the d axis. Since θ is a control phase, it changes from moment to moment. When the generator has a position / speed sensor as shown in FIG. 4, the phase obtained from the sensor is θ. When the generator does not have a position / speed sensor as shown in FIGS. 5 and 6, the estimated phase θ ^ obtained by the phase estimation calculation unit 21 is obtained.

  The UVW coordinate system is a fixed coordinate system (three-phase), and this coordinate system is normally a coordinate axis fixed at a 120 ° difference between the phases in order to match the winding arrangement of the generator. In this figure, the rotating coordinate system is indicated as d and q axes, but in order to simplify the control, the d axis and the q axis are almost orthogonal, and the direction of the d axis is the direction of the magnetic flux of the generator. However, as long as the relationship that the phase difference between one of the axes and the fixed coordinate system is θ is not necessary, they need not be orthogonal.

  The above description is a method for controlling the power generation output from the generator 2 in the wind power generation system. The system to be controlled is an AC motor, and the control device controls the current of the AC motor in accordance with the speed command or torque command. A similar method is also adopted in FIG.

Japanese Patent No. 3435474 JP 2006-246553 A

  For output (power generation output, speed / torque output) control of a rotating machine such as a generator or an AC motor, the torque command or speed command is converted into a current command using the torque command or speed command as a target value, and the rotating machine corresponding to the current command is converted. The output of the rotating machine is controlled by current control.

  However, in a system in which the rotational energy of the wind turbine that drives the rotating machine frequently and greatly fluctuates, such as a wind turbine generator, if the current control of the rotating machine is performed using the torque command or speed command as a target value, a stable power output or Torque / speed output becomes difficult. For this reason, in Patent Documents 1 and 2, in addition to being applied to a system in which the wind turbine has a variable pitch, stabilization is attempted by adjusting a transfer function of a control system, adjusting a control parameter, or the like.

  For example, in Patent Document 1, the generator controller determines a desired right-axis current in the magnetic field coordinates in response to the torque reference signal, and generates a stator electric quantity corresponding to this right-axis current. Further, the generator torque command is converted into a right-axis current representing the torque in the rotating magnetic field coordinates perpendicular to the rotor magnetic flux magnetic field, and a stator electric quantity corresponding to this right-axis current is generated. The generator controller also adjusts the generator torque by controlling the stator current at the generator's low rotational speed and controls the stator voltage at the higher generator's rotational speed. The torque is adjusted.

  These adjustments require complicated calculation elements and control elements, and a control system combining these elements may affect control responsiveness and may not allow efficient control.

  An object of the present invention is to provide a wind power generation system, a control device for a rotating machine, and a control method capable of stabilizing and controlling the output of a rotating machine without requiring complicated calculation elements and control elements.

  In order to solve the above-mentioned problems, the present invention basically uses the target value of the output control of the rotating machine as the active power command value, and this active power command value is effective by the output voltage of the inverter that controls the rotating machine output. Convert the current command value into current control of the output of the rotating machine, or set the target value of the output control of the rotating machine as the active current command value and reactive current command value, and control the output of the rotating machine with these current command values The following system, apparatus, and method are featured.

(Invention of the system)
(1) An AC generator driven by a wind turbine, a generator-side inverter that converts the generated output of this AC generator into DC power, and the DC power from this inverter synchronized with the frequency and voltage of the grid power supply In a wind power generation system comprising a system-side inverter that converts the AC power to the AC power and a control device that performs power conversion control of the inverter by current control of the generator-side inverter,
The control device uses the target value for output control of the AC generator as an active power command value, converts the active power command value into an active current command value according to the output voltage of the generator-side inverter, and converts the active-power command value to the generator-side inverter. It is characterized by comprising a control circuit for setting the current command value.

(2) An AC generator driven by a wind turbine, a generator-side inverter that converts the generated output of this AC generator into DC power, and the DC power from this inverter synchronized with the frequency and voltage of the grid power supply In a wind power generation system comprising a system-side inverter that converts the AC power to the AC power and a control device that performs power conversion control of the inverter by current control of the generator-side inverter,
The control device uses a target value for output control of the AC generator as an active power command value, converts the active power command value into an active current command value by an output voltage detection value of the generator, It is characterized by comprising a control circuit for setting the current command value.

(3) An AC generator driven by a wind turbine, a generator-side inverter that converts the generated output of this AC generator into DC power, and the DC power from this inverter synchronized with the frequency and voltage of the grid power supply In a wind power generation system comprising a system-side inverter that converts the AC power to the AC power and a control device that performs power conversion control of the inverter by current control of the generator-side inverter,
The control device sets the target value of the output control of the AC generator as an active current command value and a reactive current command value, the phase of the reactive current command value is synchronized with the magnetic flux phase of the AC generator, and the active current command A phase of the value is advanced by 90 ° from the magnetic flux phase, and a control circuit is provided which uses the reactive current command value and the effective current command value as the effective / reactive current command value of the generator-side inverter.

  (4) Of the active current command value and the reactive current command value, the active current command value is converted from an active power command value that is a target value for output control of the AC generator and an output voltage of the generator-side inverter. Or a control circuit obtained by conversion from the active power command value and the output voltage detection value of the generator.

(Invention of the device)
(5) In a control device for a rotating machine comprising an AC motor, an inverter that performs a power running operation or a regenerative operation of the AC motor, and a control device that performs power conversion control of the inverter by current control of the inverter.
The control device sets the target value of the output control of the AC motor as an active current command value and a reactive current command value, the phase of the reactive current command value is synchronized with the magnetic flux phase of the AC motor, and the effective current command value The phase is advanced by 90 ° from the magnetic flux phase during the power running operation, and is delayed by 90 ° from the magnetic flux phase during the regenerative operation, and the reactive current command value and the effective current command value are used as the effective / reactive current command value of the inverter. A circuit is provided.

  (6) Of the active current command value and the reactive current command value, the active current command value is converted from an active power command value as a target value for output control of the AC motor and an output voltage of the inverter, or the effective current command value A control circuit obtained by converting from a power command value and an output voltage detection value of the AC motor is provided.

(Invention of method)
(7) In a control device for a rotating machine comprising an AC motor, an inverter that performs a power running operation or a regenerative operation of the AC motor, and a control device that performs power conversion control of the inverter by current control of the inverter,
The control device sets the target value of the output control of the AC motor as an active current command value and a reactive current command value, the phase of the reactive current command value is synchronized with the magnetic flux phase of the AC motor, and the effective current command value The phase is advanced by 90 ° from the magnetic flux phase during the power running operation, and is delayed by 90 ° from the magnetic flux phase during the regenerative operation, and the reactive current command value and the effective current command value are used as the effective / reactive current command value of the inverter. It is characterized by having a procedure.

  (8) Of the active current command value and the reactive current command value, the active current command value is converted from an active power command value as a target value for output control of the AC motor and an output voltage of the inverter, or the effective current command value There is provided a control procedure obtained by conversion from an electric power command value and an output voltage detection value of the AC motor.

  As described above, according to the present invention, the target value for the output control of the rotating machine is set as the active power command value, and this active power command value is converted into the active current command value by the output voltage of the inverter that controls the rotating machine output. The current of the output of the rotating machine is controlled, or the target value of the output control of the rotating machine is set as the active current command value and the reactive current command value, and the current of the rotating machine output is controlled by these current command values. Stabilization control of the rotating machine output can be performed without the calculation element and the control element.

  Specifically, in a wind power generation system, it is possible to supply power to a grid system more stably than before by controlling active power, not torque or speed.

  Further, the host controller usually does not detect the output voltage of the inverter (= terminal voltage of the rotating machine). When trying to calculate the active current command from the active power command in the host controller, the inverter must send the voltage command to the controller via communication, and the controller must send the active current command after the calculation, causing problems such as responsiveness, According to the present invention, such a problem does not occur.

  Further, by detecting and feeding back the output voltage of the inverter, it is possible to perform power control based on more accurate voltage information including the inverter dead time and the IGBT Vce voltage drop.

  In addition, the number of coordinate conversion calculations is reduced as compared with the prior art, and the calculation load on the calculator can be greatly reduced. In addition, the control performance is not deteriorated in the control of the low speed (low frequency) rotating machine.

The apparatus block diagram of the wind power generation system in Embodiment 1 of this invention. The apparatus block diagram of the wind power generation system in Embodiment 2 of this invention. The apparatus block diagram and vector diagram of the wind power generation system in Embodiment 2 of this invention. The apparatus block diagram of the conventional wind power generation system. The apparatus block diagram of the conventional wind power generation system (sensorless control method). The detailed block block diagram and vector diagram of a current control system.

(Embodiment 1)
In the conventional generator shown in FIGS. 4 and 5, the generator control device of the wind power generation system controls the generator-side inverter 13 according to a torque command or a speed command. These torque commands or speed commands are given from a host controller that controls the entire wind power generation system (a controller in the central control room capable of remote monitoring control for the inverter control device).

  In a wind power generation system, it is important that energy obtained by wind can be efficiently converted into electric energy and stably supplied to an interconnected power system. Therefore, in the present embodiment, power that can be efficiently generated by the wind turbine generator from a predetermined condition such as local wind speed is obtained by calculation by the host controller, and the generator-side inverter is current-controlled using this power value as a command value.

  FIG. 1 shows an apparatus configuration diagram according to the present embodiment. This figure is a block diagram of a control device applied to a wind power generation system, and the same parts as those in FIGS. 4 and 5 are denoted by the same reference numerals.

  The active power command device 31 is set by the control device for the generator-side inverter 13, and the control device periodically obtains the effective power output of the generator-side inverter 13 from a predetermined condition such as the wind speed received by the windmill, This information is set in a register or memory in the control device. Thus, the active power output of the generator-side inverter 13 by the host controller that controls the entire wind power generation system is periodically obtained, and this information is periodically transmitted to the control device of the generator-side inverter 13 as an active power command value. This eliminates the need for processing to set in a register or memory in the control device.

  The current command calculation unit 10A performs the calculation of torque command → active current command in the current command calculation unit 10 of FIGS. 4 and 5, whereas the current command calculation unit 10A responds to the active power command value set by the active power command unit 31. The effective current command value obtained is calculated. Here, since the generator-side inverter 13 controls the generator output current by the current controller, a current command (normal active current command and reactive current command) to be given to the current controller is required. Therefore, in the calculation of the current command calculation unit 10A, signal processing is performed so that the phase (active power component) matches the phase of the voltage command signal obtained by the current control unit 12 or the like.

  The current control unit 12 compares the current command value obtained by the current command calculation unit 10A with the detection value of the generated current supplied from the generator 2 to the generator-side inverter 13, and this comparison is performed by the phase detection unit 5. A comparison is made at the detected reference phase, and a current command value for matching both is output in this comparison.

  When the efficiency of each device is ignored, the active current command value set in the active power command device 31 is calculated based on the following formula. The reactive current command value may be set in accordance with the generator characteristics so as to improve the generator efficiency.

Active current command value ∝ Active power command value ÷ Output voltage (Equation 1)
Note that the output DC voltage of the inverter 13 by the generator whose current is controlled based on the active power command value is uniquely set by the interconnected power control by the system-side inverter 17. Here, since the output voltage is not directly measured, the output voltage command of the current control unit 12 is regarded as the output voltage, and the effective current is calculated by the current command calculation unit 10A. The reactive current may be added by the current command calculation 10A or the current control unit 12. The current control unit 12 generates a voltage command for controlling the generator current so as to be an effective current command + a reactive current command. Further, since the PWM waveform to the generator-side inverter 13 varies depending on the DC voltage, the DC waveform detected by the voltage detector 16 is taken into the PWM waveform generator.

  Further, in the present embodiment, even in a system in which the generator 2 includes the phase / speed detectors 4 to 6 as shown in FIG. 4, the phase / speed estimators 21 and 22 as shown in FIG. Any sensorless control system provided can be applied.

  As described above, in this embodiment, instead of the conventional torque command, the active power command is used as a command value source, and the active current command is calculated based on the active power command and the output voltage of the generator-side inverter to perform control and operation. Therefore, it is possible to control the stabilization of the rotating machine output without using complicated calculation elements and control elements such as transfer function adjustment and control parameter adjustment of the conventional control system.

  Moreover, the merit by this embodiment is generated electric power (= active power) that is important in the control of the entire system including the wind turbine as a controller. Therefore, it is not necessary to calculate the active power command value on the host controller side, and it is not necessary to obtain the inverter voltage detection signal for this calculation. Driving is possible.

(Embodiment 2)
In the first embodiment, as shown in (Equation 1), the output voltage command is used to calculate the effective current command value given to the generator-side inverter 13, but the voltage in the semiconductor switching device used in the generator-side inverter 13 is used. Since there is a drop (eg, a voltage drop between the CE terminals of the IGBT) and a dead time for preventing a PN short circuit there, the voltage command from the current control unit 12 and the output voltage of the generator-side inverter 13 ( = Terminal voltage of the generator).

  This error will be specifically described. As the wind power generator becomes larger and the rated generated power of the apparatus becomes larger, the generator (rotary machine) becomes larger, and the generator-side inverter for controlling the generator becomes larger. When the generator-side inverter is increased in size, the semiconductor switching device used in the power conversion circuit therein has a large capacity. In recent years, an IGBT with a high switching speed is used for the semiconductor switching device (ON / OFF switching is 0.5 to 1 μsec or less in the case of IGBT). Since it usually takes about 5 μsec, an error increases between the voltage command value as described above and the output voltage of the generator-side inverter 13 (= terminal voltage of the rotating machine).

  Focusing on the above, in the present embodiment, the above error is eliminated by providing a voltage detector between the generator-side inverter 13 and the generator 2.

  FIG. 2 shows a device configuration diagram according to this embodiment. The voltage detector 32 in the figure detects the output voltage of the generator 2 and, specifically, obtains the output voltage from the line voltage using a device such as a synchronization transformer. The current command calculation unit 10A calculates an effective current command to be given to the generator-side inverter 13 using the output voltage detection signal obtained by the voltage detector 32. This arithmetic expression is, for example, as follows.

Active current command value ∝ Active power command value ÷ Output voltage (Equation 2)
According to the present embodiment, by detecting an accurate voltage by the voltage detector 32, more accurate voltage information including inverter dead time and IGBT Vce voltage drop is obtained, and the voltage information and active power command device are obtained. Since the effective current command value obtained from 31 becomes a more accurate value, more stable power supply to the system can be performed.

  Also in this embodiment, even in a system in which the generator 2 is provided with the phase / speed detectors 4 to 6 as shown in FIG. 4, the phase / speed estimators 21 and 22 as shown in FIG. The present invention can be applied to any sensorless control system provided with

(Embodiment 3)
When the wind turbine is large (total length of about 50 or more), the rotational speed of the wind turbine propeller is about 30 rotations / minute (rotation / minute is hereinafter referred to as r / m) at the highest. In a system in which a transmission gear is not used between the wind turbine propeller and the wind turbine generator, the rotational speed of the generator is also 30 r / m or less. Therefore, even when the number of pole pairs of the rotating machine is as large as several tens of poles, the frequency of the induced electromotive force is at most about 10 Hz, which is the frequency to be controlled.

  Since the control target frequency of the generator control device is about 10 Hz at maximum with respect to the calculation cycle (the clock frequency of the calculator and the gate array is several tens of MHz or more), it is possible to control without using a rotating coordinate system as in the past. The performance is not expected to drop.

Therefore, in this embodiment, the apparatus configuration diagram is the configuration shown in FIG. In (a) of FIG. 3, the active current command device 41 is set to a value corresponding to the torque current command value of the vector control system, similarly to the active current command device 31 of FIG. The effective current command value I _T ^* is calculated by the host controller, for example, according to (Formula 1). The voltage used at this time is a command value of V _u ^* · V _w ^* . In the reactive current command device 42, a flux current command when the generator 2 is an induction generator, a field weakening current command when the generator 2 is a permanent magnet synchronous generator, and the like are set as a reactive current command value I _M ^* . The current command calculation unit 43 receives the active current command value I _T ^* and the reactive current command value I _M ^{* and} outputs U-phase / W-phase current command values I _U ^* , I _W ^* (the calculation method is described below). explain).

The PI calculation unit 44 receives the U-phase / W-phase current command values I _U ^* , I _W ^* and the detected values I _U , I _W , and proportionally integrates (PIs) the respective deviations to calculate the U-phase / W Phase voltage command values V _U ^* and V _W ^* are obtained. The V-phase voltage command value calculation unit 45 calculates the V-phase voltage command value V _V ^* by calculating V _V ^* = − (V _U ^* + V _W ^* ) from the voltage command values V _U ^* and V _W ^*. Ask.

The phase estimation calculation unit 46 generates power from each phase voltage command value V _U ^* , V _V ^* , V _W ^* and each phase current command value I _U ^* , I _V ^* , I _W ^* detected by the current detector 14. An estimated value θ ^ of the rotor rotational position (phase) of the machine 2 is obtained.

  It will be described that the rotating machine can be controlled with the above configuration without using the rotating coordinate system without causing the control performance to deteriorate. The phase of the reactive current for flux control must match the flux phase of the generator. In order to control the torque effective current of the generator, the phase of the effective current must match the phase advanced by 90 ° from the magnetic flux phase when energy (electric power) is applied from the power converter to the rotating machine (power running torque). When energy (electric power) is applied from the generator to the power converter (regenerative torque), the phase must be 90 ° behind the magnetic flux phase.

These are illustrated by the vector relationship shown in FIG. In this figure, I _M ^* is a reactive current command, and I _T ^* is an active current command. The calculation formula for obtaining the U-phase current command IU * and the W-phase current command IW * from I _M ^* and I _T ^* is as follows.

I _U ^* = I _M ^* × cos θ + I _T ^* × cos (θ + 90 °)
I _W ^* = I _M ^* × cos (θ + 240 °) + I _T ^* × cos (θ + 90 ° + 240 °)
Here, all are described in cos, but a sin operation may be used in an actual arithmetic unit.

  Although the calculation is performed by the current command calculation unit 43, the control performance is not degraded by this calculation. This will be specifically described. Usually, since the speed / torque control response is about 10 rad / s, the calculation of the current command calculation unit 43 may be executed in the same calculation cycle as the speed / torque control response. It can be seen that the conventional two-phase ⇔ three-phase coordinate transformation is replaced with the calculation block in Fig. 3. However, the conventional method needs to be performed in the same calculation cycle as the current control. Is a total of two locations, one for two-phase → three-phase coordinate conversion, and one for three-phase → two-phase coordinate conversion. In the position / speed sensorless system shown in FIG. There are a total of three locations since the phase-to-two-phase coordinate transformation is increased by one location.

  On the other hand, in the present embodiment, since there is only one equivalent calculation, the calculation load on the calculator can be greatly reduced. In addition, the control performance is not deteriorated in the control of the low speed (low frequency) rotating machine.

  In the present embodiment, a configuration for controlling the currents in the U phase and the W phase is shown, but any two of the three phases of UVW may be controlled.

  Further, the first, second, and third embodiments described above show the case where the present invention is applied to the control of the generator of the wind power generation system, but the output control of the AC motor is controlled by the current control based on the torque command and the speed command of the AC motor. In place of the control device to perform, even if the AC motor output is changed frequently and greatly by performing the output control of the AC motor by current control based on the active power command value, complicated calculation elements and control elements are Stabilization control can be performed without using it.

DESCRIPTION OF SYMBOLS 1 Speed command device 2 Windmill AC generator 9 Torque command device 10 Current command calculation unit 12 Current control unit 13 Generator side inverter 14 Current detector 15 PWM converter 16 Voltage detector 17 System side inverter 31 Active power command device 32 Voltage detector 41 Active current command device 42 Reactive current command device 43 Current command calculation unit 44 PI calculation unit 45 V phase voltage command value calculation unit 46 Phase estimation calculation unit

Claims (8)

An AC generator driven by a windmill, a generator-side inverter that converts the generated output of this AC generator into DC power, and an AC that is synchronized from the DC power from this inverter according to the frequency and voltage of the grid power supply In a wind power generation system comprising a system-side inverter that converts power, and a control device that performs power conversion control of the inverter by current control of the generator-side inverter,
The control device uses the target value for output control of the AC generator as an active power command value, converts the active power command value into an active current command value according to the output voltage of the generator-side inverter, and converts the active-power command value to the generator-side inverter. A wind power generation system comprising a control circuit for setting a current command value of. An AC generator driven by a windmill, a generator-side inverter that converts the generated output of this AC generator into DC power, and an AC that is synchronized from the DC power from this inverter according to the frequency and voltage of the grid power supply In a wind power generation system comprising a system-side inverter that converts power, and a control device that performs power conversion control of the inverter by current control of the generator-side inverter,
The control device uses a target value for output control of the AC generator as an active power command value, converts the active power command value into an active current command value by an output voltage detection value of the generator, A wind power generation system comprising a control circuit for setting a current command value of. An AC generator driven by a windmill, a generator-side inverter that converts the generated output of this AC generator into DC power, and an AC that is synchronized from the DC power from this inverter according to the frequency and voltage of the grid power supply In a wind power generation system comprising a system-side inverter that converts power, and a control device that performs power conversion control of the inverter by current control of the generator-side inverter,
The control device sets the target value of the output control of the AC generator as an active current command value and a reactive current command value, the phase of the reactive current command value is synchronized with the magnetic flux phase of the AC generator, and the active current command A wind power generation comprising a control circuit that causes the phase of the value to be advanced by 90 ° from the magnetic flux phase and uses the reactive current command value and the active current command value as the effective / reactive current command value of the generator-side inverter. system.   Of the active current command value and the reactive current command value, the active current command value is converted from an active power command value as a target value for output control of the AC generator and an output voltage of the generator-side inverter, or The wind power generation system according to claim 3, further comprising a control circuit obtained by conversion from an active power command value and an output voltage detection value of the generator. In a control device for a rotating machine comprising an AC motor, an inverter that performs a power running operation or a regenerative operation of the AC motor, and a control device that performs power conversion control of the inverter by current control of the inverter,
The control device sets the target value of the output control of the AC motor as an active current command value and a reactive current command value, the phase of the reactive current command value is synchronized with the magnetic flux phase of the AC motor, and the effective current command value The phase is advanced by 90 ° from the magnetic flux phase during the power running operation, and is delayed by 90 ° from the magnetic flux phase during the regenerative operation, and the reactive current command value and the effective current command value are used as the effective / reactive current command value of the inverter. A control device for a rotating machine comprising a circuit.   Of the active current command value and reactive current command value, the active current command value is converted from an active power command value to be a target value for output control of the AC motor and an output voltage of the inverter, or the active power command value 6. A control device for a rotating machine according to claim 5, further comprising a control circuit that is obtained by conversion from an output voltage detection value of the AC motor. In a control device for a rotating machine comprising an AC motor, an inverter that performs a power running operation or a regenerative operation of the AC motor, and a control device that performs power conversion control of the inverter by current control of the inverter,
The control device sets the target value of the output control of the AC motor as an active current command value and a reactive current command value, the phase of the reactive current command value is synchronized with the magnetic flux phase of the AC motor, and the effective current command value The phase is advanced by 90 ° from the magnetic flux phase during the power running operation, and is delayed by 90 ° from the magnetic flux phase during the regenerative operation, and the reactive current command value and the effective current command value are used as the effective / reactive current command value of the inverter. A method for controlling a rotating machine comprising a procedure.   Of the active current command value and reactive current command value, the active current command value is converted from an active power command value to be a target value for output control of the AC motor and an output voltage of the inverter, or the active power command value A control method for a rotating machine according to claim 7, further comprising a control procedure obtained by conversion from an output voltage detection value of the AC motor.

Images