JPH10323051A - Switching control method for voltage-type converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a resonance phenomenon of a filter capacitor with other reactor elements, by detecting a source voltage for the filter capacitor, and adding the gain value of the harmonic component of its square value to an instantaneous effective power command. SOLUTION: A source voltage squaring circuit 3 receives as an input a voltage Vs to be applied to a filter capacitor detected by a source voltage detecting circuit, computes the square of the voltage, and outputs the source voltage square value Vs2. A harmonic component detecting circuit 4 receives the source voltage square value Vs2 as an input, and outputs its harmonic component as a harmonic component Vs2h of the square voltage value. A gain K times multiplier 5 receives the harmonic component Vs2h of the square voltage as an input, inverts its sign, multiplies it by gain K/2, and outputs its value -HVs1Vsh as a harmonic voltage command V2* to an adder 6. The adder 6 adds the harmonic voltage command V2* and an instantaneous effective power command P*, and outputs a corrected instantaneous effective power command P*<1> to a control computing means 14. Consequently, it becomes possible to suppress the oscillation of the filter capacitor current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching control method of a voltage type converter for converting an alternating current into a direct current by pulse width control. The present invention relates to a damping method for suppressing resonance of a ripple absorption filter connected to the side.

[0002]

2. Description of the Related Art FIGS. 5 to 7 are a main circuit configuration and a control block diagram of a conventional voltage source converter. This type of voltage source converter is described in the 1996 IEEJ National Industrial Application Division Conference No. 146 "Control of instantaneous distortion minimization of voltage-source converter" is well known.
The outline will be described below with reference to FIGS.

In FIG. 5, 21 is a system power supply, 22 is a system impedance, 25 is an AC voltage detector, and 26 is a PW
M converter current detector, 27 is a switching ripple suppression reactor, 28 is a PWM converter, 29 is a DC capacitor, 30 is a DC voltage detector, 31 is a load, AC voltage detector 25, PWM converter current detection , Switching ripple suppressing reactor 27, PWM converter 2
8, the DC capacitor 29, the DC voltage detector 30, and the control circuit 2 shown in FIG. 6 or FIG.

In FIG. 6, 11 is a DC controller, 12 is a means for obtaining tan (φ *), 13 is a multiplier, 14 is an AC control operation means, 1 is a voltage source converter, 31 is a load, Unit 11, means 1 for determining tan (φ *)
2. The control circuit 2 is formed by the multiplier 13 and the AC control operation means 14.

[0006] The control circuit 2 shown in FIG.
And the DC capacitor 29 detected by the DC voltage detector 30
And outputs the instantaneous active power command P * to the AC control calculation means 14 and the multiplier 13 so that the DC voltage Vd matches the DC voltage command Vd *. tan (φ
The means 12 for obtaining *) inputs the power factor angle command φ * and outputs the tangent angle tan (φ *) to the multiplier 13. Multiplier 13
Inputs the instantaneous active power command P * and tan (φ *) and outputs the instantaneous reactive power command Q * to the AC control calculating means 14.
The DC voltage Vd is controlled by the instantaneous active power command P *, and the power factor angle φ is controlled by the instantaneous reactive power command Q *.

The AC control calculating means 14 receives the power supply voltage Vs and the PWM converter current Ic so that the instantaneous active power P and the reactive power Q become as instructed and the instantaneous distortion (THD) is minimized. , The generation of the gate signal G of the PWM converter 28, that is, the selection of the switching vector.

FIG. 7 is a block diagram showing another conventional control circuit. The deviation between the DC voltage command Vd * and the actual DC voltage Vd is amplified by the deviation amplifier 15 to output a current command peak value Im. The multiplier 17 outputs the product of the fundamental wave component Vs1 of the power supply voltage Vs output by the fundamental wave component detection circuit 16 and the current command peak value Im as a current command Ic *. The gate signal generation circuit 18 is provided with an actual PWM
The PW is set so that the converter current Ic matches the current command Ic *.
A gate signal G for the M converter 28 is generated.

[0008]

However, in the voltage-source converter 1 as shown in FIG. 5, the power supply voltage Vs is generated by the ripple current accompanying the switching of the PWM converter 28.
Has a disadvantage that a ripple voltage is generated. In order to absorb the ripple current, a ripple absorption filter 33 as shown in FIG. 3, that is, a filter capacitor 24, or a filter reactor 23 and a capacitor 24 are connected. In this case, other components connected to the same system are connected. Of the nonlinear load 32 or a harmonic component included in the PWM converter current Ic, a resonance phenomenon occurs due to the system impedance 22, the filter reactor 23, and the filter capacitor 24, and the power supply voltage Vs greatly fluctuates and ripple absorption occurs. Excessive current flows through the filter.

However, the object of the present invention is that
It is an object of the present invention to provide a control method for suppressing a resonance phenomenon between the filter capacitor 24 and another reactor element in the voltage source converter 1 as shown in FIG. 3 to which a ripple absorption filter 33 for absorbing a ripple current by the WM converter 28 is connected. .

[0010]

This description has been made in view of the above points, and has the following structure. That is, the power supply voltage Vs of the filter capacitor 24 connected to the power supply side of the switching ripple suppression reactor 27 is detected, and the gain multiple value V2 * of the harmonic Vs2h of the square value Vs2 is converted to the instantaneous active power command P *. The addition has the same effect as connecting a damping resistor in parallel with the filter capacitor 24, thereby suppressing the resonance phenomenon.

Another method is to similarly suppress the resonance phenomenon by adding the gain multiple value Ih * of the harmonic component Vsh of the power supply voltage Vs to the conventional current command Ic *.

In the following, the operation of the present invention will be described based on a simplified AC equivalent circuit, which focuses only on the harmonics in FIG. 4 and grasps the vibration phenomenon. In FIG. 4, C represents the filter capacitor 24, L represents the sum of the values of the system impedance 22 and the filter reactor 23, Vs represents the filter capacitor voltage, If represents the filter capacitor current, and Ic represents the PWM converter current. , Iι represents another non-linear load current, and S represents a Laplace operator, then equation (1) holds. Equation (1) indicates that the filter capacitor current If becomes oscillating because there is no damping element in the denominator.

[0013]

(Equation 1)

When the fundamental wave component is represented by the suffix 1 and the harmonic component is represented by the suffix h, the square of the filter capacitor voltage Vs is expressed by the following equation (2). In the equation (2), if only the harmonic component is extracted and the Vsh2 term is ignored, only the 2Vs1Vsh term is obtained. Also, taking the product of the filter capacitor voltage Vs and the PWM converter current Ic to consider the power,
Equation (3) holds.

[0015]

(Equation 2)

In equation (3), taking into account that only the harmonic component is extracted and that the current flowing through the capacitor increases when the frequency increases at the same applied voltage, VshIc1
And VshIch are negligible, and are only Vs1Ich. Here, the instantaneous active power control uses the power supply voltage Vs of 2
When the control based on the harmonic component of the power is added with the opposite sign, the equation (4) is satisfied with respect to the power in consideration of the equation (3).

[0017]

(Equation 3)

Therefore, the harmonic component Ich of the PWM converter current Ic is as shown in the equation (5), and when the harmonic component Ich is substituted into the equation (1), the equation (6) is obtained.

[0019]

(Equation 4)

Since the damping element KLS exists in the equation (6), it is possible to suppress the harmonic components included in the PWM converter current Ic and the oscillation of the filter capacitor 24 due to the other non-linear load 32. Further, from the equation (5), the control of the PWM converter current Ic is directly performed by -KVsh.
The same filter capacitor 2 can be obtained by adding
4 can be suppressed.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a switching control method of a PWM converter according to the present invention is applied to a PWM converter 1 having a main circuit configuration shown in FIG. 3 will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a control circuit of a control method of a PWM converter according to the present invention. In FIG. 1, reference numeral 3 denotes a power supply voltage square circuit as power supply voltage square value output means, and 4 denotes a voltage square value harmonic. 6 is a gain K multiplier as harmonic power command output means, 6 is an adder as corrected instantaneous active power command output means, and the same reference numerals as those in FIG. 6 denote the same elements. Is shown.

The power supply voltage squaring circuit 3 includes a power supply voltage detection circuit 2
5, the voltage V applied to the filter capacitor 24 detected from
s is input, the square of the voltage is calculated, and the power supply voltage square value Vs2 is output as in equation (2). The harmonic component detection circuit 4 receives the power supply voltage square value Vs2 and outputs the harmonic component as a voltage square value harmonic component Vs2h. This voltage square value harmonic component Vs2h is given by Vsh2 in equation (2).
If the term is ignored, there is only a 2Vs1Vsh term.

The gain K-multiplier 5 has a voltage square value harmonic Vs.
2h is input, and the sign is inverted, and -KVs1Vsh obtained by multiplying the gain by K / 2 is output to the adder 6 as the harmonic voltage command V2 *. The adder 6 adds the harmonic voltage command V2 * and the instantaneous active power command P * to generate a corrected instantaneous active power command P *.
* 1 is output to the control calculation means 14. By controlling in this manner, as described in the equations (4) to (6), the oscillation of the filter capacitor current If can be suppressed.

FIG. 2 is a block diagram showing another embodiment of the switching control method of the PWM converter according to the present invention.
In the figure, the same reference numerals as those in FIG. 1 indicate the same components. The harmonic component detection circuit 4 as voltage harmonic component output means receives the voltage Vs applied to the filter capacitor 24 and outputs the harmonic component as a voltage harmonic component Vsh.

Gain K as harmonic current command output means
The multiplier 5 receives the voltage harmonic Vsh, reverses the sign thereof, and multiplies the gain K by −KVsh by the harmonic current command Ih.
It is output to the adder 6 as *. The adder 6 as a correction current command output means includes a harmonic current command Ih * and a current command Ic.
And outputs a correction current command Ic * 1 to the gate signal generation circuit 18. By controlling in this way, as described in the equation (6), the filter capacitor current If
Vibration can be suppressed.

[0026]

As described above, according to the present invention, the filter capacitor voltage Vs of the ripple absorption filter is detected, and power control using the harmonic of the square value thereof is performed, or harmonics of the filter capacitor voltage Vs are detected. It is possible to provide a switching control method of a voltage source converter capable of suppressing the oscillation of the filter capacitor by the current control using the wave component.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing one embodiment of the present invention.

FIG. 3 is a main circuit configuration diagram of a voltage source converter to which the present invention is applied.

FIG. 4 is a simplified AC system diagram for explaining the principle of the present invention.

FIG. 5 is a main circuit configuration diagram of a conventional voltage source converter.

FIG. 6 is a block diagram showing a control circuit of a conventional voltage source converter.

FIG. 7 is a block diagram showing a control circuit of a conventional voltage source converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Voltage source converter 2 Control circuit 3 Power supply voltage square circuit 4 Harmonic component detection circuit 5 Gain K multiplier 6 Adder 11 DC controller 12 Means for obtaining tan (φ *) 13 Multiplier 14 AC control operation means 15 Deviation amplifier Reference Signs List 16 fundamental wave detection circuit 17 multiplier 18 gate signal generation circuit 21 system power supply 22 system impedance 23 filter reactor 24 filter capacitor 25 AC voltage detector 26 PWM converter current detector 27 switching ripple suppression reactor 28 PWM converter 29 DC Capacitor 30 DC voltage detection circuit 31 Load 32 Other non-linear load 33 Ripple absorption filter

Claims (2)

[Claims] 1. A PWM converter for converting AC to DC,
A switching ripple suppression reactor provided on the AC side of the PWM converter, a ripple absorption filter provided on the AC power supply side of the switching ripple suppression reactor, and a control device for controlling switching of the PWM converter. In the voltage source converter provided, the control device outputs a power supply voltage square value obtained by squaring a voltage of a filter capacitor constituting the ripple absorption filter, and inputs the power supply voltage square value to convert a harmonic component thereof into a voltage. A means for outputting a square harmonic, a means for inputting the square of the power supply voltage and outputting a harmonic power command multiplied by a gain, and an instant for performing a constant DC voltage control on the DC side of the PWM converter. Means for outputting a corrected instantaneous active power command by adding the active power command and the harmonic power command,
A switching control method for a voltage type converter, comprising: controlling switching of the PWM converter so that AC power of the PWM converter follows the corrected instantaneous active power command and the instantaneous reactive power command. 2. A control device for a voltage source converter outputs a harmonic component of a voltage of a filter capacitor constituting the ripple absorption filter as a voltage harmonic component, and a harmonic obtained by inputting the voltage harmonic component and multiplying the gain by a gain. Means for outputting a current command; and means for outputting a correction current command obtained by adding the current command for performing constant DC voltage control on the DC side of the PWM converter and the harmonic current command.
2. The switching control method for a voltage type converter according to claim 1, wherein the switching of the PWM converter is controlled so that an M exchanger current follows.