CN205723093U - A kind of 220kV SCOTT balance traction transformer winding construction - Google Patents

Abstract

A 220kV SCOTT balanced traction transformer winding structure belongs to the field of railway traction transformer manufacturing. Connect the end of the high-voltage winding of the T-seat to the end of the high-voltage winding of the M-seat to form a SCOTT transformer; the T-seat is a transformer with vertical windings, and the M-seat is a transformer with horizontal windings; this SCOTT transformer transforms the three-phase 220kV voltage on the primary side into two Two-phase 2*27.5kV voltage on the secondary side, the phase difference of the two-phase voltage is 90°; adopt the SCOTT connection type of 220/2*27.5kV secondary side midpoint extraction; T-seat low-voltage windings a1, a2; a3, a4 Cross-connected to form the T-block 27.5kV outlet terminals T-N1 and t-N1; M-block b1, b2; b3, b4 respectively cross-connected to form the M-block 27.5kV outlet terminals M-N2 and m-N2. It has good insulation performance, simple structure, strong short-circuit resistance and overload capacity, and can effectively improve the stability of the power supply of the electrified railway grid, reduce the negative sequence current of the railway grid, and reduce line loss.

Description

A Winding Structure of 220kV SCOTT Balanced Traction Transformer

technical field

The utility model belongs to the technical field of traction transformer manufacturing for railways, and relates to a novel balance transformer winding structure.

Background technique

In the power supply mode adopted by traction substations of electrified railways in my country, the current on the high voltage side of the transformer is mostly an unbalanced system (such as traction transformers with VX and VV connections). With the rapid development of electrified railways in our country, it is urgent to independently develop a new structure transformer to solve the problem of unbalanced high-voltage current of traditional traction transformers.

Contents of the invention

The technical problem to be solved is to adopt a transformer with a new winding structure to ensure the three-phase symmetry of the high-voltage side current and improve the stability of the traction power transformation network.

The purpose of the utility model is to provide a 220kV SCOTT balanced traction transformer winding structure, which solves the unbalanced problem of the high-voltage power grid of the existing traction transformer.

The technical scheme adopted in the utility model:

Connect the end of the high voltage winding of the T block (the transformer with the winding vertically placed in Figure 1) to the end of the high voltage winding of the M block (the transformer with the winding horizontally placed in Figure 1) to form a SCOTT connection. This transformer converts the three-phase 220kV voltage on the primary side to the two-phase 2*27.5kV voltage on the secondary side, and the two-phase voltages have a phase difference of 90°. According to the user's requirements, the transformer adopts the SCOTT connection type with 220/2*27.5kV secondary side mid-point extraction, and the schematic wiring diagram is shown in Figure 1. According to the actual layout of the winding, in order to reduce the reactance caused by the current of the T transformer high voltage winding in the M transformer high voltage winding, a balance winding (parallel connection, one point grounding) is set inside the M transformer high voltage winding.

T-seat and M-seat iron cores respectively adopt a square-shaped iron core structure, and the winding structure is shown in Figure 2. T-seat low-voltage windings a1, a2; a3, a4, M-seat b1, b2; b3, b4 are respectively cross-connected in series to form T-seat 27.5kV outlet terminal T-N1; t-N1 and M-seat 27.5kV outlet terminal M-N2 and m-N2. Among them, TN1 and MN2 are the uplink and downlink power supply sides of the 27.5kV locomotive, and tN1 and mN2 are the uplink and downlink power supply sides of the 27.5kV locomotive.

In the design of transformer windings, semi-hard copper wires are used for the high-voltage winding wires, plus external supports, self-adhesive transposed wires are used for the low-voltage windings and balanced windings, and the inner coils are lined with cardboard tubes. According to the calculation and analysis of the transformer magnetic field, the balance winding is set. The magnetic flux leakage of the M transformer is large, and measures should be taken for the structural parts of the magnetic flux leakage path to prevent local overheating of the transformer. This technical solution realizes a symmetrical three-phase system with a primary side current and meets the requirements of a traction power supply line AT (autotransformer type) for power supply.

The difference between the new balanced traction transformer and the conventional balanced traction transformer: the middle point tap on the low voltage secondary side is convenient for on-site wiring (N1, N2, N1 and N2 are drawn from one point of the box cover in Figure 1); the 220kV high voltage winding is arranged according to Figure 2, and the design Simple and convenient wiring, thus improving the reliability of insulation.

The beneficial effects of the utility model:

The new SCOTT wiring balanced traction transformer has good insulation performance, simple structure, strong short-circuit resistance and overload capacity, which can effectively improve the stability of power supply of electrified railway grid, reduce the negative sequence current of railway grid, and reduce line loss. Two sets of the utility model have been successfully produced, and its performance index fully meets the technical requirements. Its prototype has passed the sudden short circuit test. Fill in the gaps in the country.

Description of drawings

Fig. 1 Schematic diagram of new SCOTT wiring balance traction transformer wiring

Fig. 2 Structural diagram of winding of new SCOTT connection balanced traction transformer

In the figure: 1T low-voltage TN1 winding 27.5kV, 2T low-voltage tN1 winding 27.5kV, 3T high-voltage A winding 4M low-voltage m N2 winding 27.5kV 5M low-voltage M N2 winding 27.5kV 6 balance winding P1 P1′ (P2P2′) 10kV 7M high-voltage B winding 110kV 8M high-voltage C winding 110kV.

Fig. 3 Arrangement of winding box cover of new SCOTT wiring balanced traction transformer

detailed description

The new SCOTT wiring balanced traction transformer adopts a double-body structure, and the iron cores of the T transformer and the M transformer adopt a square-shaped iron core. The traction transformer with windings arranged according to Figure 1 transforms the three-phase 220kV voltage on the primary side into a two-phase 2*27.5kV voltage on the secondary side. The two-phase voltages have a phase difference of 90°, where TN and MN are 27.5kV power supply sides, and tN, mN is the 27.5kV feed side.

In the winding structure, the two low-voltage coils of the T seat and the M seat are cross-connected and connected in series on the two columns of the single-phase square-shaped iron core, and the rated voltage is 27.5kV. 190.526kV The high-voltage coils outside the two columns of the M block are respectively B and C coils with a rated voltage of 110kV. The end of phase A of the T block is connected with the ends of B and C of the M block to form a SCOTT connection. In order to reduce the reactance caused by the high voltage winding current of the T transformer in the high voltage winding of the M transformer, a balance winding (parallel connection) is arranged inside the high voltage winding of the M transformer. According to the winding structure in Figure 2, the high-voltage primary side current is a symmetrical three-phase system, thereby solving the problem of unbalanced traction transformer power supply grid.

Claims (2)

1. A 220kV SCOTT balanced traction transformer winding structure, characterized in that: Connect the end of the high-voltage winding of the T-seat to the end of the high-voltage winding of the M-seat to form a SCOTT transformer; the T-seat is a transformer with vertical windings, and the M-seat is a transformer with horizontal windings; this SCOTT transformer transforms the three-phase 220kV voltage on the primary side into two Two-phase 2*27.5kV voltage on the secondary side, the two-phase voltage has a phase difference of 90°; use the SCOTT connection type drawn from the midpoint of the secondary side of 220/2*27.5kV; T-block low-voltage windings a1, a2; a3, a4 are cross-connected in series to form T-N1 and t-N1 of T-block 27.5kV outlet terminals; M-block b1, b2; b3 and b4 are respectively cross-connected in series to form M-block 27.5kV outlet terminal M -N2 and m-N2. 2. A 220kV SCOTT balanced traction transformer winding structure according to claim 1, characterized in that: the iron cores of the T-seat and the M-seat respectively adopt a square-shaped iron core structure.