Phase-Shifting Rectifier Transformer

Introduction

A phase-shifting rectifier transformer is a dedicated device that supplies polyphase rectified power to medium and high-voltage frequency converters. Especially with the mature development of variable frequency speed regulation technology nowadays, the localization of phase-shifting rectifier transformers is an urgent demand. To meet the market needs, we have successfully developed a series of multi-winding phase-shifting rectifier transformers based on the technology of our flagship product—unencapsulated dry-type transformers, which have been successfully applied in numerous projects.

Adopting the phase-shifting principle of the extended delta connection, the transformer can be configured as a rectifier transformer with an equivalent phase number of 9, 12, 15, 18, 24, 27 and other phases through multiple secondary windings with different phase-shift angles. Its primary side is directly connected to the high-voltage power grid, and the secondary side is equipped with multiple three-phase windings. The extended delta connection of the transformer is denoted by angles such as 0° and θ (60-θ)°, which indicate each low-voltage three-phase winding on the secondary side and the phase-shift angle of the line voltage of each low-voltage three-phase winding relative to the three-phase winding simultaneously. When each phase is connected in series with n H-bridge units, θ=60°/n, which achieves input multi-modularization and forms a 6n-pulse rectification. Thus, if each H-bridge unit features power balance and the same current amplitude, theoretically, the grid-side input current contains no harmonics lower than the (6n+1)th order, and the power factor can be improved. Generally, there is no need to equip additional reactive power compensation and harmonic filtering devices.

This transformer is most suitable for environments with high fire protection requirements and large load fluctuations, such as offshore oil platforms, thermal power plants, waterworks, metallurgical and chemical industries, mining and building materials industries and other special working environments.

Multi-winding phase-shifting rectifier transformers are custom-designed for different users, with rated capacities of 300, 400, 500, 600, 700, 800, 900, 1000, 1250, 1500, 1750, 2000, 2500 and 3500 kVA. They feature a relatively high primary impedance and a transformer efficiency of over 98%, adopt an H-class insulation system, and have a temperature rise limit of 120 K for both high and low-voltage windings. The multi-winding phase-shifting rectifier transformer is available in a variety of external structural forms customizable to user requirements, and its overall dimensions can be tailored to fit the user's installation conditions.

Performance Features

High mechanical strength, strong short-circuit withstand capacity, and safe and reliable operation;

Low noise, compact size, easy installation and maintenance-free;

High insulation level, low partial discharge, and long product service life;

Excellent moisture resistance, thermal shock resistance and fire resistance.