SU91036A1 - Three Phase Current Transmission - Google Patents

Description

The advantage of the described transmission scheme in comparison with the usual three-phase current transmission over three wires is the saving of non-ferrous metal in the wires of the line.

Fig. 1 shows the proposed circuit for switching three identical three-phase transformers at the transmitting and receiving substations; in fig. 2-vector voltage diagram in a six-phase transmission line for this transformer connection circuit; in fig. 3 is a transformer connection diagram for obtaining a three-phase overvoltage.

In the transmission scheme (Fig. 1), the tpH transmitting and lowering substations of the same three-phase transformer are connected in parallel on three-phase circuits from the low side. On the high side, the three different phases (one in each of the transformers) are connected together and grounded tightly; the remaining 6 phases of the three transformers VC; night. ts to the wireline transmission line.

This system can be represented as a three-phase system, the individual "phases of which are three-phase systems.

The voltage of any wire relative to earth is equal to the linear voltage of each of the three-phase components of it.

With the arrangement of nrovyudov-in the sequence corresponding to the following of the phases in the diagram (Fig. 2, the voltages between two adjacent wires will be equal to the linear voltage of each of the three-phase components of this system.

The three-phase load on low-voltage women with this transmission scheme is distributed evenly between all three three-phase component systems.

Voltage drops; the phases will not be the same, since in one phase of each three-phase component there will be no voltage drop in the line. However, due to the fact that different phases are grounded, on tires of lower levels (primary tires

No. 91036-2 -

substations and secondary tires — on the voltage) and the currents will be quite symmetrical.

The apparent power transmitted by the line will be equal to

where U.I is the linear voltage of each of the three-phase components of the system.

The power that comes to one wire of the transmission line will be

If this line were interpreted as a usual two-chain wire with the same linear voltages and currents in the wires,

then the transfer of power would be equal to j / 3 U., I, and the power, the arrival of u, and s on one wire:

In this way, with the proposed scheme, the transfer of Moo (bone. Coming to one wire increases by -p-1.5 times.

In case of emergency disconnection of one of the transformers of the circuit, it provides the transfer of three-phase power to the two three-phase components of the system.

In this case, the current flowing in the ground is equal to the phase current of one three-phase component of the circuit. The available power of the circuit is reduced by just a / s; There is some advantage of the circuit compared to conventional transmission with two transformers AND a double-circuit line, when turning off the transformer reduces the available power by half.

P}) and long)) to work with two-meter transformer circuits, in order to reduce the current in the ground, it is advisable to ground two free gearboxes at both ends of the line. The translation of the system into works} according to the double star scheme is also bozggen.

In the described scheme, it is advisable to use a single-phase automatic reclosing. During long-term operation without a single phase, the pa lines of decreasing available power, asymmetry, currents and voltage across the earth will be less, than in similar conditions in a conventional double-circuit line.

It should be noted that if} groups of single-phase transformers are used, the disconnection of one of the single-phase transformers will lead to the same consequences as the disconnection (|) of the ABC line. This is also true for the case when one of the transformers is disconnected in the grounded phase of the group (for example, 4; ia3a A).

In the described transmission system (Figs. 1 and 2), widespread use of three-phase branches is possible. The most distant and powerful consumers can receive power by a scaling circuit. (Fig. 1) or by a three-phase power supply (Fig. 3). Closer and less powerful consumers, can receive power from three-phase two-wire branches from the main circuit phase mains. These consumers may have the usual three-phase transforma.tori or groups of transformers operating under the scheme of DPZ.

 U.i I,

 - and, I 6 2

 1 T1 t

b / -

Subject invention

Three-phase current transmission, characterized in that, in order to reduce non-ferrous metal consumption, three different phases of three three-phase or nine single-phase transformers, the secondary windings of which are connected into stars, are connected together and grounded, and the six-wire is connected to the remaining six phases transmission line.

1

 AWW.U-A - 5

. - j i. . (.,. t I .VV.v.

, fVVWAVv-ji

IVAWHA-i- ..

.iUM. "Fl.Vf UvvVA .sA-i

- sM / AV Mr - I - v /

d- |. I p "" G5

, j.-.-. vVVWA-i J LvsA-Wf - corner 2

with

Fig.Z