JP2018046654A - Control device of power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a power converter that can accurately compensate for phase delay of a harmonic compensation signal and surely suppress a harmonic component of a power supply system.SOLUTION: A control device of a power converter comprises: a harmonic extractor 2 that sets as a phase of a power supply system a phase of a d-axis of a dq orthogonal rotary coordinate defined inside the control device of a power converter connected to the power supply system, sets an axis in an orthogonal direction of the d-axis as a q-axis, and removes DC components from d-axis components and q-axis components of DC signals of the power supply system to extract harmonic components in an arbitrary order; a phase adjustment calculator 4 that corrects a phase of the harmonic components by adding a phase correction vector determined from γ-axis components of the harmonic components to δ-axis components, in a γδ-orthogonal rotary coordinate in which the phase of the extracted harmonic components is set as the phase of a γ-axis and an axis in the orthogonal direction of the γ-axis is set as a δ-axis; and converters 5 and 6 which perform coordinate conversion of output signals to generate a command value of harmonic compensation currents to the power converter.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a power converter, and more particularly to a control device having a function of suppressing harmonic components in order to prevent malfunction of the power converter due to harmonic components superimposed on a load current. It is.

When a load including a rectifier circuit or the like is connected to the power supply system, the load current includes a harmonic component, and this harmonic component causes a malfunction of the power converter connected to the power supply system.
A so-called active filter is known as one of the means for reducing the above harmonic components.

  FIG. 6 shows an application example of the parallel type active filter. In FIG. 6, 501 is a power supply system, 502 is a connected reactor, 503 is a current detector, 504 is a load current detection filter (low-pass filter), 506 is a voltage detector, 507 is a PLL circuit, 508 is an LCL filter, and 505 is A parallel type active filter connected in parallel to the load 600 of the harmonic generation source, 505a is a harmonic detection circuit, 505b is a current controller (ACR) composed of a PI controller, 505c is a PWM signal generation circuit, and 505d is an inverter It is.

In this parallel type active filter 505, the compensation current i _C is injected into the system by the operation of the inverter 505d, thereby suppressing the harmonic component contained in the load current i _S. The harmonic detection circuit 505a generates a harmonic current command value i ^* based on the output current i _sens of the load current detection filter 504 and the phase angle θ ₁ from the PLL circuit 507.

However, in the configuration of FIG. 6, the phase of the compensation current i _C is delayed with respect to the harmonic component of the load current i _S due to the influence of the calculation delay time of the load current detection filter 504 and the current controller 505b. Ingredients may not be sufficiently suppressed.
As a countermeasure in this case, Patent Document 1 describes an active filter control device in which the command value of the compensation current i _C is advanced to eliminate the calculation delay time of the current controller.

FIG. 7 is a configuration diagram of the active filter control device described in Patent Document 1, and parts corresponding to the same functions as those in FIG. 6 are denoted by the same reference numerals.
In FIG. 7, 509 is a harmonic component extraction unit, 509 a is a dq converter that converts the load current i _S into d and q axis components i _d and i _q of the rotating coordinate system, 509 b is a transformer (voltage detector), 509c is a phase detector, 509d and 509e are high-pass filters for extracting the harmonic components of the d and q axis components i _d and i _q , 509f is an inverse dq converter, 510 is an LC filter, and 511 is a current detector. Reference numeral 512 denotes a delay unit, and 513 denotes a subtracter.

In the above configuration, the inverse dq converter 509f performs inverse dq conversion on the outputs of the high-pass filters 509d and 509e to generate a compensation current command value I _C ^* . The delay unit 512 is 360 degrees which is the phase of one cycle of the power supply voltage. The compensation current command value I _C ^* is delayed by a value (2π−θ _cmp ) obtained by subtracting the phase correction amount θ _cmp corresponding to the calculation delay time from (2π [rad]) to obtain a new compensation current command value I _C1 ^* . Generate. The subtracter 513 obtains a deviation between the compensation current command value I _C1 ^* and the compensation current detection value I _C and operates the current controller 505b so that this deviation becomes zero.

FIG. 8A shows the principle of calculating the compensation current command value I _C1 ^* . In Patent Document 1, the phase of the waveform a (compensation current command value I _C ^* ) is delayed by the delay unit 512 to obtain the waveform b (compensation current command value I _C1 ^* ). When repeated at one frequency, the waveform b appears to be advanced in phase by the phase correction amount θ _{cmp with} respect to the waveform a.
In this manner, the inverter 505d injects the compensation current i _C into the system based on the waveform b (compensation current command value I _C1 ^* ) that is advanced in phase, thereby suppressing the harmonic components of the system. .

International Publication No. 2014-091915 (paragraphs [0039] to [0046], FIG. 1 etc.)

In the prior art described in Patent Document 1, as shown in FIG. 8A, the calculation is performed using the data of the waveform a before one cycle, not the real-time data of the waveform a (compensation current command value I _C ^* ). The phase of the compensation current i _C is corrected using the apparent phase advance waveform b (compensation current command value I _C1 ^* ). That is, since the data on which the compensation current command value I _C1 ^* is based is not the latest, there is a problem that the accuracy of the phase correction is not sufficient (note that FIG. 8B is an embodiment of the present invention). explain).

  Therefore, the problem to be solved by the present invention is to provide a power converter capable of accurately suppressing the harmonic component of the system by accurately compensating for the phase delay of the compensation current caused by the calculation delay time of the control circuit including the current controller. It is to provide a control device.

In order to solve the above problem, the invention according to claim 1 detects a harmonic component of an arbitrary order included in an AC signal of a power supply system and generates a harmonic compensation signal for suppressing the detected harmonic component. Then, in the control device that is given as a command value to the power converter connected to the power supply system,
A dq orthogonal rotation coordinate is defined inside the control device, a d-axis phase of the dq orthogonal rotation coordinate is a phase of the power supply system, and an axis perpendicular to the d-axis is a q-axis,
Harmonic extraction means for removing a direct-current component from the d-axis component and the q-axis component of the AC signal of the power supply system and extracting a harmonic component of an arbitrary order;
The γ-axis of the extracted harmonic component in the γδ orthogonal rotation coordinate with the phase of the harmonic component extracted by the harmonic extraction means as the phase of the γ-axis and the axis in the direction orthogonal to the γ-axis as the δ axis The phase correction vector obtained from the component is added to the δ axis to obtain the δ axis component, and the γ axis component and the δ axis component are output as each component of the compensation signal vector whose phase is advanced from the vector of the γ axis component. Phase adjustment calculation means for
Means for converting the components output from the phase adjustment calculation means to generate the harmonic compensation signal.

  According to a second aspect of the present invention, the control device according to the first aspect further comprises amplitude correction means for correcting a harmonic amplitude error caused by the operation of the phase adjustment calculation means.

  According to a third aspect of the invention, there is provided the power converter control device according to the first or second aspect, further comprising amplitude correction means for correcting a harmonic amplitude error caused by coordinate conversion of the output signal of the phase adjustment calculation means. It is a thing.

In the present invention, rotational coordinate conversion is performed in synchronization with harmonic components of an arbitrary order, and a phase correction vector corresponding to a desired phase correction amount is added to the result to correct the phase of the harmonic compensation signal.
Thereby, compared with the prior art, it is possible to perform more accurate phase correction of the harmonic compensation signal, and it is possible to surely suppress the harmonic component present in the power supply system and to prevent malfunction of the power converter.

1 is a block diagram showing a first embodiment of the present invention. It is a vector diagram for demonstrating operation | movement of the phase adjustment calculator in 1st Embodiment. It is a figure which shows the relationship between the d-axis and q-axis load current harmonic component before (gamma) delta conversion in 1st Embodiment. It is explanatory drawing of the (gamma) delta conversion result in 1st Embodiment. It is a block diagram which shows 2nd Embodiment of this invention. It is a figure which shows the example of application of a parallel type active filter. It is a block diagram of the prior art described in patent document 1. FIG. FIG. 8A is a diagram illustrating a calculation principle of a compensation current command value, FIG. 8A is according to Patent Document 1, and FIG. 8B is according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the following embodiment, the load current detection value i _sens includes the fundamental wave component and the Nth harmonic component of the power supply system. Although the case where the phase of the current detection value is corrected will be described below, the present invention can also be applied to the case where the phase of the voltage detection value is corrected.

FIG. 1 is a block diagram showing a first embodiment of the present invention.
In FIG. 1, a dq converter 1 performs coordinate conversion of a three-phase load current detection value i _sens into d-axis and q-axis load currents I _Sd and I _Sq . The d-axis and the q-axis are control axes constituting orthogonal rotation coordinates, and the phase of the d-axis is set equal to the system voltage phase θ _vs , and the q-axis is an axis that is advanced by 90 ° from the d-axis. On the d and q axes, the fundamental wave component of the load current detection value i _sens is a DC component, and the harmonic component is the (N−1) th AC component. In the dq converter 1, cos [theta] _vs determined by cos · sin calculator 7, sin [theta _vs is used to coordinate transformation.

The harmonic extractor 2 removes DC components included in the d-axis and q-axis load currents I _Sd and I _Sq and extracts d-axis and q-axis load current harmonic components I _Sh1d and I _Sh1q , respectively.
The γδ converter 3 performs coordinate conversion of the d-axis and q-axis load current harmonic components I _Sh1d and I _Sh1q into the γ-axis and δ-axis load current harmonic components I _Sh1γ and I _Sh1δ . The γ-axis and δ-axis are also control axes constituting orthogonal rotation coordinates, and the phase of the γ-axis is the phase of the harmonic load current I _Sh1γδ (vector sum of I _Sh1γ and I _Sh1δ ), and the δ-axis is 90 ° from the γ-axis. The axis of advance direction. Therefore, the harmonic load current I _Sh1γδ is only the γ-axis load current harmonic component I _Sh1γ , and the δ-axis load current harmonic component I _Sh1δ is zero. The function of this γδ axis converter 3 will be described in detail later.

The phase adjustment computing unit 4 has the γ-axis load current harmonic component I _Sh1γ , the δ-axis load current harmonic component I _Sh1δ (= 0) and the phase correction amount θ _cmp by the action of the phase correction vector computing unit 4a and the adder 4b. Then, a δ-axis current component I _βδ for phase correction is obtained. Here, the phase correction amount θ _cmp is a correction amount corresponding to a calculation delay time of a control circuit such as a current controller (ACR) measured in advance.

FIG. 2 is a vector diagram for explaining the operation of the phase adjustment calculator 4.
The phase adjustment calculator 4 _outputs the γ-axis load current harmonic component I _Sh1γ (= I _Sh1γδ ) as it is as the γ-axis current component I _βγ , and the phase correction vector calculator 4 a calculates the phase correction vector ( A δ-axis current component I _βδ (= I _αδ ) is output by adding the δ-axis vector) I _αδ to the δ-axis load current harmonic component I _Sh1δ (= 0) by the adder 4b.
[Equation 1]
I _αδ = I _Sh1γ × tan θ _cmp
As a result, as shown in FIG. 2, a compensation signal vector I _βγδ (combined vector of I _βγ and I _βδ ) whose phase is advanced from I _Sh1γ (= I _βγ ) by the phase correction amount θ _cmp can be generated.

The inverse γδ converter 5 converts the input γ-axis and δ-axis current components I _βγ and I _βδ into d-axis and q-axis load currents I _βd and I _βq . This calculation is performed by the reverse process of the γδ converter 3.
Furthermore, the inverse dq converter 6, cos [theta] _vs determined by cos · sin calculator 8, using sin [theta _vs, d-axis output from the inverse γδ converter 5, q axis load current I _.beta.d, the I _Betaq, It converts into a three-phase harmonic compensation current i _cmp as a harmonic compensation signal. This calculation is performed by a process reverse to that of the dq converter 1.
The harmonic compensation current i _cmp is given as an output current command value to an inverter not shown.

Next, the operation of the above-described γδ converter 3 will be described.
FIG. 3 shows the relationship between the d-axis and q-axis load current harmonic components I _Sh1d and I _Sh1q before γδ conversion, and FIG. 4 shows the γδ conversion result.

From FIG. 3, the d-axis and q-axis load current harmonic components I _Sh1d and I _Sh1q are (N−1) th order alternating current, and I _Sh1d has a phase T / 4 with respect to I _Sh1q (T is the period of I _Sh1d ). ) Is going on. That is, as shown in FIG. 4, the d-axis and q-axis load current harmonic components I _Sh1d and I _Sh1q are the difference angles between the load current harmonic angular frequency ω _h and the system voltage angular frequency ω _s on the dq axis. It can be thought of as a vector that rotates with frequency. The cosine and sine of this vector can be _replaced by d-axis and q-axis load current harmonic components I _Sh1d and I _Sh1q , respectively.

Therefore, by performing the calculation of Equation 2, the d-axis and q-axis load current harmonic components I _Sh1d and I _Sh1q are synchronized with the harmonic load current phase θ _hdq and the γ-axis and δ-axis load current harmonic components I _Sh1γ , I _Sh1δ can be converted.

Here, FIG. 8B is a diagram illustrating the calculation principle of the compensation current command value according to the present embodiment. In FIG. 8B, the waveform a corresponds to the vector I _Sh1dq composed of the d-axis and q-axis load current harmonic components I _Sh1d , I _Sh1q, and the vector obtained by rotating the waveform a with the γδ converter 3. A corresponds to the vector I _Sh1γδ composed of the γ-axis and δ-axis load current harmonic components I _Sh1γ and I _Sh1δ . The above-described operation of the phase adjustment calculator 4 advances the phase of the vector A by the phase correction amount θ _{cmp and obtains the} compensation signal vector I _βγδ composed of the vector B, that is, the γ-axis and δ-axis current components I _βγ and I _βδ. Thus, _obtaining the d and q-axis load current I _βdq by inversely transforming I _βγδ corresponding to the vector B by the inverse γδ converter 5 corresponds to obtaining the waveform b ′.

The waveform b ′ in FIG. 8B obtained in this way has a phase advanced by θ _{cmp with} respect to the waveform a. That is, as is apparent from comparison with FIG. 8A described as the prior art, in this embodiment, rotational coordinate conversion, phase advance processing, and inverse conversion are performed using real-time data of I _Sh1dq (waveform a). Thus, the compensation signal vector I _βγδ (waveform b ′) can be obtained, and the harmonic compensation current i _cmp can be finally obtained by performing inverse dq conversion on this I _βγδ .
For this reason, compared with the prior art, it is possible to accurately compensate the harmonics of the system without being affected by the calculation delay time.

Next, a second embodiment of the present invention will be described.
FIG. 5 is a block diagram showing the configuration of the second embodiment, and parts having the same functions as those in FIG. 1 are denoted by the same reference numerals.
This second embodiment is different from the first embodiment of FIG. 1 in that a first amplitude corrector 9 and a second amplitude corrector 10 for correcting an amplitude error generated by the phase correction process are replaced with an inverse γδ converter 5. It is provided before and after.

First, the first amplitude corrector 9 corrects an amplitude error generated by the processing by the phase adjustment calculator 4 described above. In the phase adjustment calculator 4, as is clear from FIG. 2, the compensated signal vector I _βγδ after the calculation has a larger amplitude than the vector I _Sh1γδ before the calculation. The increase rate of the amplitude is obtained by Equation 3.
[Equation 3]
Increase rate = √ {(I _Sh1γ ² + I _βδ ² ) / I _Sh1γ ² }
Therefore, the first amplitude corrector 9 corrects the amplitude error by multiplying the compensation signal vector I _βγδ by the reciprocal of the increase rate to generate the components I _β1γ and I _β1δ of the vector I _β1γδ .

従って、上記の増減率の逆数の２乗を、逆γδ変換器５から出力されるベクトルＩ_β１ｄｑの各成分Ｉ_β１ｄ，Ｉ_β１ｑに乗算して各成分Ｉ_β２ｄ，Ｉ_β２ｑ（ベクトルＩ_β２ｄｑ）を生成することにより振幅誤差を補正し、これらの成分Ｉ_β２ｄ，Ｉ_β２ｑを逆ｄｑ変換器６に入力して高調波補償電流ｉ_ｃｍｐを求めることとした。 Next, the function of the second amplitude corrector 10 will be described.
In the γδ conversion calculation and the inverse γδ conversion calculation, the amplitude of the converted vector increases or decreases according to the amplitude of the dq-axis harmonic load currents _ISh1d and _ISh1q . The increase / decrease rate of the amplitude of the vector before conversion and after conversion can be obtained by Equation 4.

Accordingly, each component I _β2d , I _β2q (vector I _β2dq ) is multiplied by the square of the reciprocal of the above increase / decrease rate by multiplying each component I _β1d , I _β1q of the vector I _β1dq output from the inverse γδ converter 5. By generating the amplitude error, the components I _β2d and I _β2q are input to the inverse dq converter 6 to obtain the harmonic compensation current i _cmp .

  The present invention can be used as a control device for various power converters that perform AC / DC conversion or DC / AC conversion.

1: dq converter 2: harmonic extractor 3: γδ converter 4: phase adjustment calculator 4a: phase correction vector calculator 4b: adder 5: inverse γδ converter 6: inverse dq converter 7, 8: cos Sin calculator 9: first amplitude corrector 10: second amplitude corrector

Claims (3)

Detects harmonic components of any order included in the AC signal of the power supply system, generates a harmonic compensation signal for suppressing the detected harmonic components, and sends a command value to the power converter connected to the power supply system In the control device given as
A dq orthogonal rotation coordinate is defined inside the control device, a d-axis phase of the dq orthogonal rotation coordinate is a phase of the power supply system, and an axis perpendicular to the d-axis is a q-axis,
Harmonic extraction means for removing a direct-current component from the d-axis component and the q-axis component of the AC signal of the power supply system and extracting a harmonic component of an arbitrary order;
The γ-axis of the extracted harmonic component in the γδ orthogonal rotation coordinate with the phase of the harmonic component extracted by the harmonic extraction means as the phase of the γ-axis and the axis in the direction orthogonal to the γ-axis as the δ axis The phase correction vector obtained from the component is added to the δ axis to obtain the δ axis component, and the γ axis component and the δ axis component are output as each component of the compensation signal vector whose phase is advanced from the vector of the γ axis component. Phase adjustment calculation means for
Means for coordinate-converting each component output from the phase adjustment calculation means to generate the harmonic compensation signal;
An apparatus for controlling a power converter, comprising: In the control apparatus of the power converter according to claim 1,
An apparatus for controlling a power converter, comprising amplitude correction means for correcting a harmonic amplitude error caused by the operation of the phase adjustment calculation means. In the control apparatus of the power converter according to claim 1 or 2,
An apparatus for controlling a power converter, comprising amplitude correction means for correcting a harmonic amplitude error caused by coordinate conversion of an output signal of the phase adjustment calculation means.

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