JPS6151220A - Reactive power compensating device - Google Patents

Abstract

PURPOSE:To attain an ecomomical device by providing one set of tapped single phase reactor, three sets of single phase capacitors having at least two intermediate taps and a semiconductor switch in place of three sets of single series reactors of each stage. CONSTITUTION:The start of winding of the series reactor 2 is connected to one end of a power line and one end of single phase capacitors 1a, 1b, 1c is connected respectively to the other end of the power line. The capacitance ratio of the single phase capacitors is constitued as 1a:1b:1c=1:2:4. The reactance and winding ratio of each inermediate tap of the series reactors 2 is selected as those for 1a:for 1b:for 1c=4:2:1, and the series reactor 2 for the capacitor 1a having the smallest capacitance has the largest winding number and connected to the end of winding. The series reactor 2 for the 1c having the largest capacitance is connected to the intermediate tap of he minimum number of turns. A applying/ drawing-out signal of a control section 4 controls the semiconductor switches 3a, 3b, 3c to attain combination of the capacitance in 7 states thereby applying a proper load phase reactive power to the added reactive power.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reactive power compensator for intermittent and irregularly fluctuating loads such as welding machines.

Conventional technology A conventional reactive power compensator will be explained with reference to FIG.

Single-phase capacitors 1a, 1b, IC and series reactor 2a
, 2b, 2C and semiconductor switches 3a, 3b, 3C are connected in series, respectively, and are connected in parallel to the same power supply line. In this way, the single-phase capacitor capacity ratio of the three groups is 1a:
1b:IC-1:2:4, and the input group is switched in the input control section 1 4, and seven levels of capacity can be obtained by the combination.

Problems to be Solved by the Invention In such a device, three types of single-phase devices are required. In particular, in the series reactor, three units were required for the phase reactor, which was expensive and took up a lot of space.

In addition, the smaller the capacity, the more frequently it is turned on, and the design requires a thermal margin, resulting in a large series reactor, which is uneconomical.

In order to eliminate such drawbacks, the present invention provides one tapped single-phase series reactor with at least two intermediate taps instead of three single-phase series reactors in each stage. It was constructed using

Example Next, one embodiment of the present invention will be described with reference to FIG.

The configuration of the present invention includes a single-phase capacitor 1a and a semiconductor switch 3.
a and the winding end of the series reactor 2 are connected in series. One end of the series circuit of the single-phase capacitor 1b and the semiconductor switch 3b is connected to the intermediate tap of the series reactor 2, and one end of the series circuit of the single-phase capacitor 1c and the semiconductor switch 3G is connected to the other intermediate tap of the series reactor 2. has been done. The winding start of the series reactor 2 is connected to one end of the power supply line, and the other end of the power supply line is connected to one end of each of the capacitors Ia, lb, and Ic.

The capacitance ratio of single-phase capacitors 1a, Ib, and 1c is la:l
b:1c=1:2:4, and on the other hand, the actance and turns ratio of each intermediate tap of the series reactor 2 are 2 for la, 2 for lb=I
For C -, 1: 2:1, 1 with small capacitor capacity
The series reactor 2 for a has the maximum number of turns and is connected to the end of the turn.

Moreover, the series reactor 2 for the IC with the largest capacitance is connected to the center tap with the minimum number of turns.

In operation, the semiconductor switches 3a, 3b, and 3C are controlled by the closing and tripping signals of the control unit 4, and seven stages of capacity combinations are performed to supply appropriate phase-advanced reactive power to the additional reactive power.

In the embodiment shown in FIG. 2, a triac is used as the semiconductor switch, but an anti-parallel switch or a general switch may also be used.

Further, although an example of a series reactor with two intermediate taps has been shown, other different numbers of intermediate taps can be similarly applied. .

Effects of the Invention As mentioned above, by using an intermediate tap () single-phase series reactor instead of three single-phase series reactors, the series reactor can be manufactured in a small size and at low cost. Because a large amount of heat can be obtained,
As a reactive power compensator, it is an extremely economical device.

[Brief explanation of drawings]

FIG. 1 is a circuit explanatory diagram of an embodiment of the reactive power compensator of the present invention, and FIG. 2 is a circuit explanatory diagram of a conventional reactive power compensator. 1a, Ib, lc: Single-phase capacitors 3a, 3b, 3c: Semiconductor switch 4: Control section 2: Intermediate tap series reactor 1 9.1 Applicant: Niki Capacitor Industry Co., Ltd. Figure 1 fa, bu b , tc: Single-phase capacitor 2: Intermediate tuff II reactor 37a, 3b, 3C
:Semiconductor switch 4:Yu+ltq part@2 Figure--King Σ mouth S X″1a

Claims (1)

[Claims] In a reactive power compensator connected to an AC power source and connected in parallel with a load, one end of the winding start of a series reactor having at least two intermediate taps is connected to one side of the power supply line, and the A semiconductor switch (3c) and a single-phase capacitor (1c) are connected in series from an intermediate tap, and a semiconductor switch (3b) and a single-phase capacitor (1b) are connected from a second intermediate tap of the series reactor.
are connected in series, and a semiconductor switch (3a) and a single-phase capacitor (
1a) are connected in series, and one end of each single-phase capacitor is connected in common to the other side of the power supply line.