DE3150385C2 - Static network coupling for high performance for coupling a three-phase network with a higher frequency and a single-phase network with a lower frequency - Google Patents

Abstract

Static network coupling for high performance for coupling a three-phase network with a higher frequency and a single-phase network with a lower frequency with a frequency-reducing direct converter connected to the three-phase network with a three-phase output, with two phase outputs connected to the single-phase network and each via an electronic phase shifter to balance the load with the third phase output and an electronic phase shifter with parallel capacitance for the entire single-phase reactive power, which is arranged between the phase outputs connected to the single-phase network, has the task of also achieving a return of energy from the single-phase to the three-phase network without additional circuitry. This is achieved in that the phase inversion required when the electrical energy is fed back from the single-phase network is continuously carried out electronically by switching over the control angle of the direct converters. A particular area of application is traction power supply.

Description

The invention relates to a static network coupling for high power to the coupling ewies three-phase network with higher frequency and a single-phase network lower frequency according to the preamble of the present claim.

From DE-OS 29 39 514 a "device for the transmission of electrical energy of high power from a three-phase supply network of higher frequency in a single-phase Lastfietz lower frequency" is known, which uses for Frequencyuntersetzu g Drchstrom direct converters that feed a single-phase network that after known Steinmetz method with adjustable reactance compensated and symmetries is.

Such a circuit is shown in FIG. The direct converters 5,6,7 convert the three-phase network with a higher frequency 13 into a three-phase network with a lower frequency and feed via a transformer T which is connected between the outputs of the direct converters 5 and 6. the single-phase network 14 and two suction circuits 8, 9, which are between the outputs of the direct converters 5 and 6 and 6 and 7 and each consist of a capacitor and an inductor, connected in series, and three connected inductors 10, 11, 12, whose Structure is shown in Fig. La and of which the first between the outputs of the direct converters 5 and 6, the second between the outputs of the direct converters 6 and 7 and the third between the outputs of the direct converters 5 and 7.

The electrical energy flows from the three-phase network for a single-phase network, the direct converters must generate a clockwise symmetrical voltage system at the output (terminals 1, 2, 3).

If the direction of energy is to be reversed, either suction circuit 9 / must wipe connections 1 and 3 or the feeding right-hand rotary field by swapping connections 2 and 3 can be transformed into a counterclockwise one. However, this is not provided for in the circuit arrangement according to the aforementioned Offenlegungsschrift. In the case of the device for energy transmission, therefore, can also not be of a network coupling are spoken.

It is known from DE-OS 20 30 222 a circuit arrangement in which two electrical networks over a converter are connected, wherein the voltage of the first network is lower than that of the second network In order to transfer energy from the first to the second network, inductances are switched on in the strings of the first network to the converter, in which energy is stored by periodically short-circuiting certain of these strings, which is then stored during the opening time is transported to the second network

The object of the invention is that by DE-OS 29 39 514 known device for the transmission of electrical energy from the three-phase in to expand the single-phase network so that one energy Return delivery from the emphasis to the three-phase network is possible without special additional circuitry

This is achieved according to the invention by the features listed in the characterizing part of the patent claim

The phase sequence is thus determined at a certain point in time by switching over the control functions of the direct converters oc \ (t), ai (t), oc- ^ i), see FIG. 1, swapped Two conditions must be met:

1. The time course of the output voltage ui2 between the direct converters 5 and 6, VgL Fig. 1, must remain unaffected by the phase switching. 2. The time course of the output voltage U23 between see the direct converters 6 and 7, see. Fig. 1, must remain constant with respect to the Gi undschwachse so that no unacceptably high compensating currents flow in the capacitor in the compensation device 9.

The output voltages u _{) 2} , u ₂ j, u ₃₎ (uz ,: output voltage between the direct converters 7 and 5) are derived from the phase voltages u \, U ₂ , U3 according to the equations

U | ₂ = Ui-Ii ₂

U ₂₃ = U ₂ -Ui

t / 31 = Uj-U)

educated. Conditions 1, 2 can be fulfilled if the phase voltages are mirrored at the vertical at the zero crossing of (Uz (Uj) = O), see FIG. 2, in which the phase stresses mirrored at t = t _u on the vertical are shown. At this point in time applies

and

u _} (tu) "- u _} (tu) U \ (h:) = - u ₂ (tu) U ₂ (Hi) = - u \ (tu)

Therefore, there is a constant switching of the control functions x, (t). *} (t), Λϊ (0 possible. After switching, the following applies

U, (t>

In) = -

If you insert GL (7,8) in (1), you can see that
does not change

and U3l ('i> tlj) = -Ul - (- U ₃ ) -U ₂ = U ₃ -Ul = - U ₂ - (—1 / |) = U3l (Ktu) Furthermore applies U23fi> tu) = - u ₃ - {- u ₂ ) = U ₂ -U ₃ = U ₂₃ (t <tu)

(10)

(H)

10

(12)

15th

which shows the reversal of the spin injis.

3 shows the course of the control functions and after switching for sinusoidal modulation. In Fig. 2 are the resulting phase stresses a three-phase twelve-pulse direct converter

If one forms according to the GIn. (1), (2), (3) the concatenated Voltages, the harmonics, which can be divided by three, drop out. The results in FIG. 4 shown Curves.

The simulation results confirm the correct ones with regard to compliance with the required conditions Selection of the changeover time, which always returns after 772 and an electronic phase reversal with a dead time which is equal to half the network period duration is allowed

The specified method for reversing the phase sequence is of course not applicable to phases 2 and 3 It can also be limited to the other two phases by cyclically swapping the phase names 1.2 and 1.3 are used.

Special advantages of the static network coupling according to of the invention consist in the fact that there is no additional expense compared to the known device mentioned at the beginning on switching devices it is necessary that the switching process has only a short dead time and no compensation oscillations after the original stop process appear.

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For this purpose 4 sheets of drawings

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55

fcO

Claims (1)

Claim: Static network coupling for high performance for coupling a three-phase network with a higher frequency and a single-phase network with a lower frequency Frequency with a frequency-reducing direct converter connected to the three-phase network a three-phase output where two phase outputs connect to the single-phase network and each via an electronic phase shifter to balance the load with the third phase output and an electronic phase shifter with parallel capacity for the entire single-phase reactive power, which is arranged between the phase outputs connected to the single-phase network, characterized in that the phase reversal required when the electrical energy is fed back from the single-phase network is electronically continuously reversed by switching over the Control angle} of the direct converter takes place.