JPH0382338A - Higher harmonic voltage suppressing apparatus - Google Patents

Abstract

PURPOSE:To obtain an active type higher harmonic suppressing apparatus which is provided with a load equipment in parallel and normalizes a voltage at a power receiving point by providing transformation matrix signal generating means, transformed voltage signal generating means, higher harmonic voltage signal generating means, compensating current signal generating means and switching command generating means for switching the three-phase PWM converter. CONSTITUTION:A transformation matrix generating circuit 81 is the function generator of the fundamental harmonic angular frequency of a system power supply voltage. A transformed voltage generating circuit 82 outputs transformed voltage Vsp and Vsq signals. A high-pass filter 83 outputs transformed voltage AC component Vsp and Vsq signals. A higher harmonic voltage generating circuit 84 outputs higher harmonic voltage VSHU, VSHV and VSHW signals. A proportion al integration circuit 85 outputs three-phase compensating current command values i U, i V and i W. A current control circuit 86 outputs a switching command VG signal so that compensating current detection values follow the compensating current command values and controls ON and OFF of switching elements forming a three-phase PWM converter.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a harmonic voltage suppressing device installed in parallel with load equipment of a power supply system, and particularly to an active type harmonic voltage suppressing device that suppresses harmonic voltage at a power receiving point. [Prior Art] A system shown in FIG. 5 is known as a system for suppressing harmonic voltages in a tS system. Figure 5 is shown to explain a conventional example of a harmonic voltage suppression system, where l is the system power supply, 2.7 is the load, 3 is the synchronous filter, 4 is the transformer, 5 is the voltage compensation capacitor, and 6 is the power supply. It is impedance. Here, load 2 indicates a tangential load to the power receiving point, and load 7
indicates a linear load such as an induction machine connected to power receiving point B. Furthermore, the voltage compensation capacitor 5 is a so-called 601L capacitor. As shown in the figure, in this type of harmonic voltage suppression method, a tuned filter 3 that resonates with harmonics is provided near a load 2 that generates harmonics tft, and the tuned filter 3 absorbs harmonic currents. The generation of harmonic voltages is suppressed by preventing wave currents from flowing through the system power supply 1. [Problems to be Solved by the Invention] In the power supply system diagram shown in FIG. Therefore, if a large harmonic voltage is generated at the receiving point,
A large harmonic current flows through the voltage compensation capacitor 5 for voltage compensation, which is connected in parallel with the load 7 equipment in the power supply system, and as a result, the series reactor of the voltage compensation capacitor 5 overheats and burns out. . [Means for Solving the Problems] The present invention has been made in view of the above points, and
This is achieved by implementing an active harmonic suppression device that is installed in parallel with load equipment and can normalize the voltage at power receiving point B. Specifically, first, the control circuit means of the three-phase PWM conversion device includes a conversion matrix signal generation means. Conversion voltage signal generation means, harmonic voltage signal generation means. The apparatus includes a compensation current signal generating means and a switching command generating means for a three-phase PWM converter of a three-phase PWM converter. Second, the main configuration includes a voltage compensation capacitor and the like together with the three-phase PWM converter, and the control circuit means of the three-phase PWM converter includes the same components as the first control circuit means, and further includes a voltage compensation capacitor. It is equipped with means for generating a switching signal to the switch. [Operation] Next, this solution and its operation will be explained in detail with reference to FIG. 6. FIG. 6 is shown to facilitate understanding of the basic technical idea of the present invention, and ysr and V8H are line 1121.
1', the fundamental wave component and harmonic component of the voltage v8, i8 is the power supply current, jL is the load current, and i ( is the compensation current. In other words, the power supply DC iB flowing from the system power supply l' flows through the reactor 6'. After that, the load current IL flowing through the linear load 2' and the compensation current j( flowing through the suppressor 3') are divided. Therefore, this can be expressed by the following formula: IJl = l(, +1(...・・・・・・・・・・・・
(1) Here, the voltage vc applied to the linear load 2' becomes a sine wave due to the compensation current Ec, and the load current IL In order to be supplied from ', the voltage drop V of the reactor 6' needs to be as follows. However, the inductance of the reactor 6' is assumed to be L. Solving this for the power source 1 current iS results in two equations, and substituting equation (1) into this, equation (3) is obtained.As shown above, as the compensation current 1c, the system power supply voltage harmonic component compensation current, In other words, the voltage vC applied to the load becomes a sine wave by flowing the component written in the right-hand side of equation (3).Next, we will explain how to derive the harmonic component of the power supply voltage.・Each of the three phases Transformation matrix that rotates the voltage VSU * vsv l VSW at the fundamental wave angular frequency ω

When the coordinates are transformed using [0], the following equation is established. Here, vsp and vsq indicate the p-axis component and q-axis component of the instantaneous spatial voltage vector, and their interaction vsp
and vsq are caused by voltage distortion components, so the three-phase distortion voltage Vsgtr * Vsiitv *
Vsuw is determined by the following formula. In addition, (03-” is

It is an inverse transformation matrix of [0]. From this, the three-phase distortion voltage V8HU e vsiv * VBln of the power supply voltage of the receiving demon as shown in FIG.
From l and leakage inductance L of transformer 4, formula (3)
Therefore, the 3*, *, * phase compensation current command value 1ctr t tcv + tcw can be obtained as follows. Therefore, by flowing a current equal to the compensation current command value shown in equation (8) to each phase, the power receiving point B shown in FIG.
The power supply voltage can be made into a sine wave. Furthermore, if the leakage inductance L of the transformer 4 is currently unknown or if the power receiving demon is far away from the power receiving point B, the three-phase distortion of the power supply voltage at the power receiving point B W pressure V8HU *
V8HV + VIIHW 'e derived L, and based on Tsukino formula (9), three-phase compensation current value iCU + 'CV
Similar harmonic voltage suppression can be achieved by deriving r ICW. Furthermore, as shown in equation (8), the compensation current command value is inversely proportional to the inductance L of the compensation reactor 6',
Here, in order to reduce the capacity of the three-phase PWM converter, it is necessary to increase the inductance L. However, when the inductance L is increased, the fundamental voltage at the power receiving point B decreases due to the delayed current of the load. Therefore, when the voltage at power receiving point B drops due to the delayed current of the load, by dropping a voltage compensation capacitor to power receiving point B, the power factor of the current can be improved and the voltage at power receiving point B can be normalized. . [Embodiment] FIGS. 1 and 2 show the main structure and control circuit of an embodiment of the present invention, and 8 is a three-phase PWM converter. In the figure, parts with the same symbols as in FIG. 5 indicate parts having the same functions. That is, a three-phase PWM converter 8 is connected to the power receiving point B, and as shown in the figure, the three-phase PWM converter 8 is a three-phase PWM converter that forms a three-phase circuit using switching elements and diodes. The three-phase PWM converter is configured to include a DC capacitor between terminals on the DC side and an AC reactor in series on the AC side. The control circuit of the three-phase PWM conversion device 8 is a control circuit shown in FIG.
．． Conversion voltage generation circuit 82, bypass filter 83. The main components are a harmonic voltage generation circuit, a proportional-integral circuit 85, and a current control circuit. Now, in FIG. 2, the transformation matrix generation circuit 81 is a function generator of the fundamental wave angular frequency of the grid power supply voltage, and the transformation matrix expressed by equation (5)

[0] and the inverse transformation matrix (0) expressed by equation (7) are output as a transformation matrix signal. The converted voltage generation circuit 82 generates the voltage V8U + V at the power receiving point B.
BV +VSW and transformation matrix

Input the [0] signal and use the formula (4
), the converted voltages Vsp, V, and q signals are output. The bypass filter 83 inputs the converted voltage Vsp and Vsq signals and outputs the converted voltage AC external vsp and vsq signals. The harmonic voltage generation circuit condition is converted voltage AC outside v3. . Input the v3q signal and the inverse transformation matrix Co) signal, and use the formula (
6) Based on harmonic voltage v8HU・vsuv j V
Outputs 81nF signal. The proportional-integral circuit 85 has a harmonic voltage vs■υ+ vsttv
l The current control circuit 86 inputs the V8HW signal and outputs the three-phase compensation current command value icv + based on the formula (9).
tcvs, *King. 1 and the three-phase compensation current detection value iCU * iCv + tcw flowing into the three-phase PWM converter, and outputs the switching command vG as a signal so that the compensation current detection value follows the compensation current command value, and the three-phase PWM converter Controls the on/off of switching elements that make up the converter. Therefore, in this embodiment, by controlling the compensation current, the harmonic region pressure at the power receiving point B can be suppressed. FIG. 3 and FIG. 4 show the main part configuration and its control circuit of another embodiment of the present invention, where 9 is a compensation reactor;
10 is a switch, and 101 is a capacitor control circuit. In the figures, the same reference numerals as in FIG. 5, FIG. 1, and FIG. 2 indicate parts having the same functions. That is, in FIG. 3, the compensation reactor 9 is the load equipment,! It is inserted in series with the pressure compensation capacitor and the power supply side of the three-phase PWM converter, and its inductance value corresponds to L in equation (8). Further, the voltage compensation capacitor 5 is normally constituted by a capacitor with a 60-volt capacitor, and this is connected to or disconnected from the power receiving point B by a switch 10. Furthermore, in FIG. 4, in particular, the conversion voltage generation circuit 82 is set to the voltage Vsty + Vsv + Vsv at the receiver 1 point 0 (F).
signal transformation matrix

[0] is input, and in this point it is different from the one in which one input is used to obtain the voltage signal of the power receiving point B shown in FIG. In addition, the proportional integral circuit 85*,
* is used to obtain the three-phase compensation current command value tcU#1cV*icW based on the formula (comb). Therefore, the control circuit shown in FIG. Furthermore, the capacitor control circuit 87 inputs the voltage vstr #VBV + VB''W at the power receiving point B, and if the voltage is below a certain value, generates a switch vG' to compensate for the voltage. Connect the capacitor 5 to the power receiving point B, or connect the voltage compensation capacitor 5 to the power receiving point B if it exceeds a certain value.
separate from Therefore, in this other embodiment, by controlling the compensation current, the harmonic region pressure can be suppressed, and furthermore, the fundamental wave voltage can be brought to a normal value. In addition, in this explanation, a voltage compensation capacitor is used to control the fundamental wave voltage, but it is possible to perform more fine-grained voltage control by flowing leading or lagging current using a three-phase PWM converter. Of course. [Effects of the Invention] As explained above, according to the present invention, based on a special technical concept, harmonic voltage of the grid is detected and a compensation current is applied to cancel it, thereby changing the voltage at the receiving point into a sinusoidal waveform. It is possible to provide a device which is extremely useful in practice and which can maintain the fundamental wave voltage at a normal value.

[Brief explanation of drawings]

1 and 2 are system diagrams showing the main part configuration of one embodiment of the present invention, and a program diagram showing its control circuit, and FIGS. 3 and 4 are main parts of other embodiments of the present invention. Fig. 5 is an explanatory diagram showing a conventional example of a harmonic voltage suppression system; Fig. 6 facilitates understanding of the basic technical idea of the present invention. FIG. 1.1'...System power supply, 2, 2', 7.
...Load, 4...Transformer, 5...
...Voltage compensation capacitor, 8...3-phase PWM converter, 9...Compensation reactor, 10...
...Switch.

Claims (1)

[Scope of Claims] 1. A harmonic voltage suppressing device connected in parallel with a load equipment to a power supply system, comprising a three-phase PWM converter and a three-phase PWM converter.
The main configuration includes a DC capacitor connected between the DC terminals of the WM converter, an AC reactor inserted in series with each phase on the AC side of the three-phase PWM converter, and a control device that controls the three-phase PWM converter. In addition, means for outputting a conversion matrix signal rotating in synchronization with the power supply frequency to the control device, means for inputting the receiving point voltage and the conversion matrix signal and outputting a converted voltage signal, means for removing the DC component and outputting a converted voltage AC component signal; means for inputting the converted voltage AC component signal and the conversion matrix signal to output a harmonic voltage signal; and means for inputting the harmonic voltage signal and outputting a compensation current signal. A harmonic wave generator characterized by comprising means for outputting a command signal, and means for inputting the compensation current command signal and the compensation current detection signal and outputting a switching command to a switching element constituting the three-phase PWM converter. Voltage suppressor. 2. A compensation reactor inserted in series in the power supply system, a voltage compensation capacitor connected in parallel to the load equipment on the opposite side of the compensation reactor, a switch for opening and closing the voltage compensation capacitor, and a three-phase PWM converter. The three-phase PWM converter comprises a three-phase PWM converter, an AC reactor inserted in series with each phase on the AC side of the three-phase PWM converter, and a DC terminal of the three-phase PWM converter. means for outputting a conversion matrix signal that rotates in synchronization with the power supply frequency to the control device; means for inputting the power supply side voltage of the compensation reactor and the conversion matrix signal and outputting the converted voltage signal; means for removing the DC component of the converted voltage signal and outputting the converted voltage AC component signal; and the converted voltage AC component signal. a means for inputting the harmonic voltage signal and a conversion matrix signal and outputting a harmonic voltage signal; a means for inputting the harmonic voltage signal and outputting a compensation current command signal; and a means for inputting the compensation current command signal and the compensation current detection signal. A means for outputting a switching command to a switching element constituting the three-phase PWM converter, and a means for inputting a load equipment receiving point voltage and outputting a signal for opening and closing the switch depending on the level of the load equipment receiving point voltage. A harmonic voltage suppression array characterized by: