JPS58212326A - Harmonic filter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] related to data.

- When a consumer has a source of harmonics, such as power conversion equipment, a harmonic filter is installed to remove the harmonics generated from this source.

FIG. 1 schematically shows a normal harmonic filter provided on the consumer side. In the figure, 1 is, for example, a six-phase converter provided to a consumer, 2 is a filter, and 3 is an AC power source. Filter 2 is connected in parallel with converter 1 which generates harmonics. Power supply impedance for harmonics is Z
s, the tool tie impedance is zF, and the harmonic current from converter 1 is I.

This is expressed as the distribution from the customer side when the converter is in operation.

As shown in this equation, the harmonic filter effect is determined by the relative relationship between the filter impedance zF and the power source impedance Zs with respect to the harmonics. However, if there is a harmonic generation source other than the 6-phase blitz converter 1 to be suppressed in the same system, these harmonics will be input to the filter, so it is necessary to take into account the target object when designing the filter. It is necessary to investigate other harmonic sources, and the filter capacity will also be excessive.

As a measure to prevent such an increase in filter capacity, the second
As shown in the figure, a method has been attempted in which a blocking reactor (CBR) 4' is installed in series on the power supply side to completely block the harmonic current flowing into the harmonic filter.

In this method, in order to increase the harmonic filter effect, it is desirable to increase the value of BR, but there is an upper limit due to the voltage drop of the fundamental wave.

In order to improve the above-mentioned drawbacks, the present invention provides a harmonic absorption filter composed of one capacitor and one reactor with an intermediate tap, in which one end of the rib toilet 8 lacking the intermediate tap is used as a power source, and the intermediate tap is connected to the intermediate tap. The harmonic filter has one end connected to a load that is a source of harmonics, and the other end connected to a capacitor, providing a highly versatile harmonic filter.

The embodiments shown in the drawings will be described below.

FIG. 3 shows an embodiment of the invention. A reactor with an intermediate tap 5 wound around the same iron core is connected to an AC power source 3 at one end P, and a six-phase bridge converter 1 is connected by an intermediate tap S.
The other end T is connected to the capacitor 6.

If the overall number of turns of the coil is 1+α, the turns ratio from P to the intermediate tap point 5t-r is 1, and the turns ratio from the intermediate tap point S to the other end T is α, the embodiment is shown in FIG. Represented by an equivalent circuit.

If the coupling coefficient between the coils is 100%, in this equivalent circuit, the magnitude of reactance Xp is l+α, the magnitude of reactance x5 is 1α, and the magnitude of reactance X is α+α2.

In this embodiment as well, as in the case shown in FIG. 2, the following needs to be taken into consideration.
::1'' (1) In order to reduce the voltage drop of the fundamental wave, there is an upper limit to the reactance of the BR with an intermediate tap (approximately 4 to 15% based on load capacity.
1 corresponds to this].

(2) Capacitors connected in parallel also serve to improve the power factor of the load, but there is an upper limit to prevent phase advance (40% for a diode bridge and 60% for a thyristor bridge based on load capacitance) (The phase advance capacity is 250% and 167% if expressed as reactance.)

Considering the above conditions, the fundamental wave reactance of the intermediate tapped BR is set to 6% and 10%, and the 6-phase diode bridge load and the 6-phase thyristor bridge load SC
Regarding R, the optimum constant for implementing the present invention was determined, and furthermore, the harmonic temporary absorption effect was determined by comparing it with that shown in FIG. The results are shown in Table 1. In comparison with Fig. 2, it is assumed that the filter in Fig. 2 has one set of fifth shunts, and the value of 9BR and the phase advance capacitance of the capacitor are the same, and in Table 1, Xc is the capacitor fundamental wave reactance. Therefore, the term "absorption effect" is a comparison with the harmonic filter shown in Fig. 2, but in the present invention, the equivalent reactance XP on the AC power supply side of BR is equal to The absorption effect becomes stronger as the fundamental wave reactance becomes thicker.

Table 1 (a) Xo/X7=25=(5)2. Xp= (1
+ a) x BR, X7= (a+a”)XBR, absorption effect = Xp/XBR, The filter effect is expressed as the ratio of the harmonic current ISn flowing to the power supply side and the harmonic generation source current In.

According to Table 1 and FIG. 5, the larger the filter effect Iri and the power supply side reactance xP, the greater the effect.

In this regard, in the present invention, by utilizing mutual reactance, an effect of 1.4 to 1.9 times can be obtained.

Furthermore, in the case of the bag cylinder shown in Fig. 2, two accelerators are required: BR4 and the reactor for the fifth harmonic shunt.
According to the present invention, only one device is required.

Further, by inserting a braking resistor 7 between S and T as shown in FIG. 6, the effect of absorbing higher harmonics can be increased. The field resistance is 100 based on the load capacity.
It is set to about 100096.

Although the above embodiment describes a three-phase load having a harmonic generation source, it is clear that the same effect can be obtained for a single-phase load as well. However, it is necessary to give special consideration to constants.

As explained above, according to the present invention, not only circuits having harmonic generation sources such as thyristors and diodes, but also
For example, it can be used in circuits that widely include harmonic generation sources, such as televisions.

4 Brief Explanation of the Drawings ':1 Figure 1 is an example I of a normal harmonic filter provided on the consumer side.

FIG. 2 is an example of a harmonic filter that suppresses the inflow of harmonics.

FIG. 3 shows an embodiment of the invention.

49 shows an equivalent circuit of the embodiment of FIG. 3.

FIG. 5 is a graph showing the harmonic absorption effect according to the present invention.

FIG. 6 shows another embodiment of the invention.

1... 6-phase bridge converter, harmonic filter, 3...
・Chichiryu Yoigen, 4...Blocking reactor (BR)
, 5... Blocking reactor with intermediate tap, 6
... Capacitor, 7. Braking resistor.

Agent Patent Attorney Hidekan Aoki −°÷11 Yoshi 1 figure 7r2 figure

Claims (3)

[Claims] (1) In a harmonic absorption filter consisting of one capacitor and one reactor with an intermediate tap, one end of the reactor having the intermediate tap is used as a power source, the intermediate tap is used as a harmonic generation source, and the other end is used as a power source. A harmonic filter characterized by connecting a capacitor to a capacitor. (2) The fundamental wave reactance of the intermediate tapped reactor is selected to be 4 to 15% based on the load capacity, the turns ratio of the reactor is selected to be 04 to 1.0, and the fundamental wave reactance of the capacitor is selected to be 150 to 300%. A harmonic filter according to claim 1. (3) To improve the harmonic absorption effect, 100 to 100
3. The harmonic filter according to claim 1 or 2, wherein a 0% braking resistance is inserted.