JPS61170237A - Filter device - 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 [Technical Field of the Invention] The present invention relates to a DC filter device for absorbing harmonic voltages contained in a DC circuit.

[Conventional technology]

The DC filter device is constructed as shown in FIG. 1 as described in the "Silicon Rectifier for Mitsubishi Electric Railway Substation" leaflet L-31387D (filter in FIG. 4).

In the figure, (1) is a conversion device that is a source of harmonics;
(2) is a series reactor, and (3) is a parallel resonant shunt.

Parallel resonant shunt (3) Beam axle (inductance L [
H]), and a capacitor (electrostatic capacitance C[li')), which corresponds to the frequency of the harmonics to be removed from the DC circuit. On the other hand, the series axle (2) serves to suppress the harmonic current flowing from the converter (1) into the parallel resonant shunt (3) to an appropriate value.

Now, in electric railway substations, etc., it is common to increase the number of converters (1) one after another in accordance with the increase in train load, but simply adding converters (1) as shown in Figure 2 is not enough. Because the harmonic current is divided depending on the ratio of effective resistances, the current imbalance between the two devices is very large, and in the worst case, it may flow only to one side. This is because it is extremely difficult to manufacture a parallel resonant shunt, especially the reactor, while accurately controlling its effective resistance. In Fig. 2, (1) and (10 are converters, (2) and (e) are series reactors, and (3) and C11 are parallel resonant shunts. Therefore, conventionally, converters were added. If so, either remanufacture the parallel resonant shunt to one with a current capacity that matches the number of converters, or install a high-current parallel resonant shunt from the beginning in consideration of future expansion plans. The only option was to leave it in place, which was extremely uneconomical.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above. When adding a parallel resonant shunt, harmonics are By adding resistors such that the lapse resistance in terms of number is equal in each parallel resonant shunt and maintaining the specified filter effect, the stain flow can be balanced and economical capital investment can be made. The purpose is

Note that as the resistance value of the resistor increases, the current balance between the parallel resonant shunts improves, but the filtering effect worsens, so the constant must be set so that the specified filtering effect (harmonic reduction rate) can be maintained. It goes without saying that it is necessary to select the

[Embodiments of the invention]

FIG. 3 shows an embodiment of the present invention in detail with respect to only the parallel resonant path 5]. In the figure (5o)
, (6o) are two parallel resonant shunts, (51), (6
1) is a resistor according to the present invention. In addition, in this figure, rT,
, rC indicate the effective resistance of the reactor and capacitor, respectively.

The problem with the conventional method is that when comparing (rLl + rcl) and (rL2 + rC2), the values were extremely different depending on the device, so the currents of parallel valve distribution Wj (50) and (60) were greatly different. That's a thing.

-Like the invention of power tree (rLl +rC1+R1) -(rL
2 +rC2+R2) as small as possible.
By selecting 2 and adding it to each resonant shunt, the problem of current imbalance is solved.

In fact, in order to make the filter effect as good as possible, the resistance value of R1 is selected so that the smaller of R2 becomes zero, that is, a resistor is added only to the shunt with the smaller effective resistance. It is a good idea to

In the above example, the number of parallel resonant shunts in parallel is two, but the same effect can be obtained even if there are three or more. [Effect of the Invention] As described above, according to the present invention, the parallel resonant shunt Since the filter device is configured to eliminate the problem of branching of the flow, the filter device can be made compact and inexpensive, and the advantages of the present invention are particularly exhibited when the filter device d is expanded.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the circuit configuration of a filter device, Fig. 2 is a diagram in which two units of the equipment shown in Fig. 1 are connected in parallel, and Fig. 3 shows an embodiment of the present invention, especially only the parallel resonant shunt portion. The circuit diagram is 0 (1), (10...conversion device, (2),)...
・Series reactor, (3)'t' C ([t... Parallel resonant shunt, (5o), (ao)... Parallel resonant shunt (detailed diagram), (51), (61)... Resistor Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] In a filter device comprising a series body of a reactor and a capacitor, and a plurality of filters connected to both poles of a DC circuit to absorb harmonic components contained in the DC circuit, at least one of the series bodies is connected to a plurality of filters. A filter device characterized in that a resistor is inserted in series in one series body.