JPS6096134A - Plural tuning branch type power filter circuit - 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 The present invention relates to a double-tuned shunt type power filter circuit.

A conventional example is shown in FIG. That is, a tank circuit in which an auxiliary capacitor 3 and an auxiliary reactor 4 are connected in parallel is connected in series to a series circuit of a main capacitor 1 and a main reactor 2, and two resonance points A□ are connected as shown in FIG.
, A, constitutes a double-tuned shunt type filter circuit. Note that in this circuit, accessories such as a Q adjustment resistor and a current transformer are omitted.

By the way, when implementing this power filter circuit, in order to make the equipment compact, each circuit element is housed in tanks 5 to 7 at earth potential, as shown in Figure 3, and the spaces between them are insulated with oil or SF6 gas. They are connected by connecting pipes 9 and 10. 8 is a lead-in bushing, 11 is its conduit, and 12 is a ground. In this case, one main capacitor 1 is used, but a plurality of main capacitors 1 may be used depending on the capacity. Further, although the auxiliary capacitor 3 is housed in a tank 7 separate from the main capacitor 1, it may be housed in the same tank 5. Further, the auxiliary capacitor conduit 10 employs a double conductor system to reduce the size of the conduit 10.

However, a current several times larger than the current flowing through the main capacitor 1 and the main reactor 2 flows through the tank circuit.

For example, in the case of the 11th to 13th branches, the current magnification factor is about 6 times. The first inflow current for DC power transmission
If the 1st harmonic current and the 13th harmonic current are about 200 A, the expanded current values are about 1200 A each. Therefore, in this power filter circuit, the number of parallel electric wires constituting the auxiliary reactor 4 increases, and the number of parallel elements of the auxiliary capacitor 3 increases, making processing and assembly complicated, and the structure becomes larger. There is a drawback that it does. In addition, since the current is a harmonic, there is local overheating due to the eddy current product of the structure, and in particular, the conduit 10 has a large diameter and becomes complicated in order to prevent overheating of the conductor extraction part of the tank 6.7 and the conduit 10. be.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a double-tuned shunt type power filter circuit that can reduce the current in the tank circuit, facilitate manufacturing, and further reduce the size and cost.

An embodiment of this invention is shown in FIGS. 4 to 6. That is, in this double-tuned shunt type power filter circuit, the main reactor is composed of a high impedance transformer 13, and its leakage impedance is used as the reactor 1, and an auxiliary capacitor 3' and an auxiliary reactor 4 are provided on the secondary side. A tank circuit 14 is connected in parallel with the main capacitor 1', and the primary side of the transformer 130 is connected in series with the main capacitor 1'.

FIG. 5 is an equivalent circuit of this circuit, and since the high impedance transformer 13 uses an iron core, the excitation impedance is 15.
However, since this excitation impedance 15 is usually an order of magnitude larger than the impedance of the main circuit, it can be ignored.

In addition, the current flowing through the tank circuit 14 can be reduced by setting the turns ratio of the transformer 13. For example, if the turns ratio is set to about the current expansion rate described above, local overheating will occur due to the eddy current product of the structure described above. It can be pressed to the extent that it does not occur.

FIG. 6 shows the structure of equipment in which the circuit of this embodiment is implemented. As in the case of FIG. 3, each circuit element 1', 3', 4', 13 is housed in a tank 5' to 7' at earth potential for compactness, and the space between them is filled with oil or SF.
They are connected by pipes 9' and 10' insulated with 6 gas or the like. Other parts corresponding to those in FIG. 3 are given the same reference numerals with a dash added.

In this structure, the current flowing through the conductor of the conduit 10' is smaller than that of the conventional conductor, and the generation of a conduit current product is small, so that the conduit 10' can be made small in diameter, and may be made of carbon steel, for example. In this case, the multi-conductor system is adopted, as in the case of FIG. 3. Also, although the main capacitor 1' is composed of one unit, it may be composed of multiple units depending on the capacity, and the auxiliary capacitor 3' is stored in a tank 7' separate from the main capacitor 1'. As in the case of FIG. 3, there are cases where the two are stored in the same tank 5'.

Because of this configuration, when comparing the high impedance transformer 13 of this embodiment with the main reactor 1' of the conventional example, the embodiment requires an iron core and two windings, primary and secondary. Therefore, the price will rise. However, as mentioned above, there is no need to take measures against local overheating due to the eddy current product, and the conductor lead-out portions of the tanks 6' and 7' and the conduit 10
Since the filter can be made of carbon steel and have a small diameter, the filter equipment as a whole can be made more compact. Further, the coil is easier to manufacture, and the number of elements of the auxiliary capacitor is reduced, making it easier to manufacture and further downsizing.

As described above, in the double-tuned shunt power filter circuit of the present invention, a high-impedance transformer is connected in series with the main capacitor to form the main reactor.
Since the tank circuit is connected to the next side, the current in the tank circuit can be reduced, the tank circuit elements can be easily manufactured, and the overall structure can be made more compact and cost-effective.

[Brief explanation of the drawing]

Figure 1 is a conventional power filter circuit diagram, Figure 2 I''i
An impedance characteristic diagram of the double-tuned shunt system, FIG. 3 is a schematic structural diagram of the power filter circuit, FIG. 4 is a power filter circuit diagram of an embodiment of the present invention, and FIG. 5 is an equivalent circuit diagram thereof. FIG. 6 is a schematic structural diagram of the circuit of this embodiment. 1'...Main capacitor, 3'...Auxiliary capacitor,
4'... Auxiliary reactor, 13... High impedance transformer, 14... Tank circuit agent Patent attorney Government Mistake 1 t6 -ffl frequency (Hz) Fig. 3

Claims (1)

[Claims] A main capacitor, a high impedance transformer connected in series to this main capacitor to form a main reactor, and a tank circuit connected to the secondary side of this transformer and consisting of an auxiliary reactor and an auxiliary capacitor connected in parallel. A double-tuned shunt power filter circuit equipped with a power filter circuit.