JPS5932364A - Power converter - Google Patents

Abstract

PURPOSE:To have higher harmonics tuned and absorbed by a tertiary winding side impedance and a filter impedance, and lower harmonics tuned and absorbed by the primary and tertiary impedance and a filter impedance by a method wherein a filter is provided on the side of a tertiary winding of a rectifying transformer. CONSTITUTION:Tertiary windings 6A and 6B are provided on rectifying transformers 2A and 2B, high harmonic filters 3a, 3b, 4a and 4b are connected to the windings 6A and 6B, and they are turned to the eleventh harmonic wave and the thirteenth harmonic wave using the tertiary equivalent impedance of the rectifying transformer 2A or 2B, or the impedance of higher harmonic filter 3a, 4a or 3b, 4b. Also, using the primary and tertiary impedance of rectifying transformer 2A or 2B and the impedance of higher harmonic filters 3b, 4b or 3a, 4a, the above is turned to the fifth and seventh harmonic waves.

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a power converter equipped with a harmonic tweeter that completely prevents harmonic current generated by a rectifier from flowing into a power supply system. [Technical background] A rectifier, known as a source of harmonic current,
When the current becomes large, it is generally divided into multiple units to configure multiphase rectification to minimize the generation of harmonic currents. Now, if the number of rectification phases is P, then the order of the generated high stabilization current is n
It is expressed as XP±1 (n: integer), and its magnitude is expressed as 1/(nXp±1) of the fundamental wave current, assuming that the waveform is completely rectangular. For example, if the number of rectification phases is 6, the order is fi,
7, 11.13, 17.18... and the magnitude is the fundamental wave 115.1/7.1/11.1/13.1/17.1/
A harmonic current of 19... is generated, and if the total number of rectification phases is 12, the orders are 11.13, 23.25... and the magnitude is 1/11, 1/13, 1/231/25 -. harmonic current is generated. As mentioned above, if 12-phase rectification is used, the fifth. Although the 7th harmonic is canceled out, the 11.13 ii waves, etc. still remain, and if this 11.13 harmonic causes a problem for the grid, a harmonic tweeter can be installed to absorb them and send them to the grid. It is necessary to prevent the leakage of Figure 1 shows two rectifiers IA for one DC load. Power is supplied by two rectifier transformers 2A and 2B, which constitute 1B and 12-phase rectification, with phases of 30 degrees, and two 11-harmonic filters 3a, 3b and 13-harmonic filter 4.
4a and 4b show a conventional rectifier system with a tweeter that attempts to reduce the influence of harmonics on the system bus 5 as much as possible. In this conventional system, if one of the two rectifiers is stopped due to failure or inspection and power is supplied by one rectifier, this is not a 6-phase rectification, and as mentioned above, the 5th harmonic, the 7th harmonic, and
Harmonics occur. In general, the system 5 is inductive, and the 11th and 13th harmonic filters 3a, 3J
4a and 4b are [5114 waves silk 7 harmonics, tel d capacity i
This causes parallel resonance near the fifth harmonic between the system 5 and the harmonic ficitors 38, 3k), 4a, 41), and the generated sieve PII4*Mst increases from several times to several tens of times. is amplified to greatly distort the electric ratio waveform of system bus B. - Even if the DC outputs supplied by the two rectifiers JA and Ill are unbalanced, a similar phenomenon occurs in which the 9th and 7th harmonics are generated. [Object of the Invention] The present invention e aims to solve these problems and provides a device that can easily absorb high frequencies. [Summary of the Invention] The present invention provides a rectifier that converts alternating current voltage into m-current voltage, a secondary winding connected to the rectifier, a primary winding connected to the power transmission system, and an electromagnetic A plurality of transformers each having a tertiary winding coupled to the tertiary winding, a harmonic absorbing capacitor connected to the tertiary winding of this transformer, and an accelerator connected in series to the capacitor. In the power converter equipped with the transformer, the reactance between the secondary winding and the tertiary winding of the transformer, the reactance of the hyreactor, and the capacitance of the capacitor are converted into the 5th harmonic or the 7th harmonic generated from the R adjustment device. 1 of the transformer.
Next, the reactance between the two blowing glands is the primary winding 3 of the other transformer.
Actance between the next windings and this tertiary winding

[In series with the 11th or 13th harmonic generated by the rectifier in combination with the capacitance of other capacitors connected in series and the reactance of other capacitors connected in series with this capacitor. This is a power conversion device that includes a tertiary winding and a reactor that resonate. That is, the present invention comprises a multiphase rectifier comprising two or more rectifier transformers with tertiary windings and a rectifier, and a harmonic filter connected to the tertiary side of each rectifier transformer. The transformer's third-order equivalent impedance and harmonic filter have a tuning point for high-order harmonics to be removed,
The present invention is also a power conversion device +ffi with a harmonic filter, characterized in that it has a tuning point for lower harmonics to be further removed by the impedance between the primary and third orders of the rectifier transformer and the harmonic filter. Since the present invention is constructed as described above, the rectifier transformer has three parts.
By installing a filler on the next winding side, high-order harmonics are equalized by 3rd-order equivalent impedance and filter impedance.
When one rectifier out of two or more rectifiers is stopped, or when there is current discontinuity between multiple identical rectifiers, the low-order harmonics are absorbed by the first-order third-order impedance and the above-mentioned filter impedance. This has the effect that it is possible to provide a rectifier with a harmonic ficitor that does not cause parallel resonance in low-order harmonics that occur when there is balance. [Embodiments of the Invention] Next, the present invention will be explained in detail. Figure 2 shows a rectifier IA that converts AC voltage into a DC voltage, and 2 connected to the rectifier IA.
The primary winding 11 connected to the next winding m12 and the power transmission system, and the tertiary windings 6A and 6B electromagnetically coupled to these windings.
A plurality of transformers 2A and 2B equipped with ffi, capacitors 3A and 4A for harmonic absorption connected to the tertiary winding 6A of the two transformers, and capacitors 3A and 4AK each connected in series and an accelerator 13A. , 14A, the flux actance between the secondary and tertiary windings of the two transformers and the reactor flux actance 13A, 14A.
In addition, the capacitance of capacitors 3A and 4A is a rectifier.] The capacitance of capacitors 3A and 4A resonates in series with the 5th harmonic or 7th harmonic generated from A, and the actance between the primary and secondary windings of the two transformers is the same as that of the transformer. Reactance between the primary winding and tertiary winding of 2B and capacitor 3 connected in series to the tertiary winding
B, 4B capacitance and capacitor 3B, 4
B are connected in series to each other, or the handles 13B and 14B are connected in series.
Tertiary winding 6B and reactors 13B, 14B that are combined with the glue actance and resonate in series with the 11th or 13th harmonic generated from the rectifier IA.
1 shows a power conversion device equipped with k. FIG. 2 is a single line diagram of the rectifier system with a filter according to the present invention.
A, 613 is provided, and harmonic filters 3a, 3b are installed on this.
, 4a, 4b It is connected, and M 111t14! The wave and the 13th harmonic are tuned (series resonance), and the rectifier transformer 2B (
Or 2A) between the primary and tertiary impedance (Zta
) and harmonic filters 3b, 4b (or 3a, 4
b) To tune to the 5th and 13th harmonics (series resonance) with the impedance of ↓ 5.7, 11.13
This is intended to prevent the leakage of 1lAi waves to system 5. The operation and effectiveness of the present invention will be specifically explained by comparing the conventional system and the present invention system with examples. Now, the capacity of rectifier transformers 2A and 2B is 1OMVA, 1st
1st harmonic harmonic filter - 3a, 3b 3MVA, M
13fl1417 (/letter e 1.4 MVA
, System 5 has a short circuit capacity of 25 at 50 Hz and 11 KV.
0MVA. Also, consider the case where one of the two rectifiers is stopped, that is, in six-phase operation. However, the rectifier transformer of a stopped rectifier shall be operated to utilize the filter. FIG. 3 is an equivalent circuit for harmonic current of a conventional system. Inr is a harmonic current that occurs more often than the rectifier IA, and the fifth harmonic is 100A based on 11Kv. 7th is 71A1 11th is 45A, m13 harmonic power is 38 people. Ins is the harmonic current flowing out to system 5, V
ns is the harmonic voltage distortion of system 5. Based on the harmonic impedance for the equivalent circuit in Figure 3, the harmonic current Ins flowing out to the system 5 and the voltage distortion Vn due to this harmonic current.
Table 1 shows the calculation of s, and the current of the 5th harmonic is 8.
It can be seen that it is amplified 22 times, and therefore the fifth harmonic voltage distortion is as high as 32%. Table 1 Harmonic current and voltage values Figure 5 is an equivalent circuit for the system of the present invention, 6
A and 6B are the tertiary equivalent impedances of rectifier transformers 2A and 2B with tertiary windings, 1J) IIKV base IJ 7
Kutas are each 0.157 ohm tossle. 7A, 7B
is the primary and tertiary impedance of the rectifier transformers 11i2A and 2B, and the real reactance is 1.3 ohm. In this equivalent circuit, the 3rd order equivalent impedance is X6A, the reactance is 0.188 ohm, and the capacitance is 40.
Tuned to the 11th order with a 3 ohm filter 3A,
Similarly, impedance is 6A and reactance is 0.352.
It is tuned to the 13th order with a filter 4a having a capacitance of 86.3 ohms. If such conditions are satisfied, the 11131i14 which occurs more often than the rectifier IA
The wave is absorbed by a harmonic filter 4a consisting of a capacitor and an accelerator. On the other hand, in the above six impedance values, the first @ third order impedance 7B of the rectifier transformer 2B and the fifth order of the harmonic filter 3b-1 are tuned, and similarly the impedance filter 3B and the harmonic filter 4 are tuned.
It tunes to the 7th order at b. Under such conditions,
The 5.14th wave current generated by the rectifier IA is absorbed by the harmonic filters 3b and 4b before flowing out to the system 5. Table 2 shows a calculation example showing the filter effect in the system of the present invention. I understand.

[Brief explanation of the drawing]

Fig. 1 is a single line diagram showing a conventional rectifier with a harmonic filter, Fig. 2 is a single line diagram showing a rectifier with a harmonic filter of the present invention, and Fig. 3 shows that the rectifier IB stops at the m1 diagram. This is the harmonic equivalent circuit when the 1.DC load, lA, iB... Rectifier 2A
, 2B...transformer, 3A, 3B, 4A, 4B...
・Capacitor 6A, 6B...Third winding.

Claims (1)

[Claims] A rectifier that converts an AC voltage into a total DC voltage, a secondary winding connected to the rectifier, a primary winding connected to the power transmission system, and a tertiary winding electromagnetically coupled to these windings. In the power conversion device, the power converter includes a plurality of transformers, a harmonic absorbing capacitor connected to the tertiary winding of the transformer, and an accelerator connected in series to the capacitor. The actance between the secondary winding and the tertiary winding of the transformer, the reactance of the reactor, and the capacitance of the capacitor resonate in series with the 5th harmonic or the 7th harmonic generated from the rectifier. In addition, the reactance between the primary and secondary windings of the transformer is the reactance between the primary and tertiary windings of another transformer, the capacitance of another capacitor connected in series with this tertiary winding, and this A tertiary winding and a reactor that are combined with the reactance of one other small actuator connected in series with the capacitor to resonate in series with the 13th harmonic or the 13th harmonic generated from the rectifier. A power conversion device comprising: