Novel Step-Up Topologies of Zigzag Autotransformer

Abstract

Zigzag autotransformer is widely used in multi-pulse rectifier system. However, the traditional zigzag autotransformer does not have the step-up function. Meanwhile, by improving the zigzag autotransformer structure, the output voltage can be increased without additional auxiliary components. Therefore, based on the 12 pulse rectifier system, this paper analyzes and designs three zigzag autotransformer step-up topologies, establishes the corresponding mathematical topology, studies the relationship between the transformation ratio and system main parameters, and deduces the step-up range of the three topologies. When the transformation ratio is greater than or equal to 1.0353 and less than 2.0705 and when the transformation ratio is greater than or equal to 2.0705, the equivalent capacity of the three topologies are compared. Based on the comparison, the optimal topology is obtained in different cases. Finally, according to the theoretical analysis, the simulation parameters are set, the simulation circuit is built, and the results are analyzed combined with corresponding mathematical topologies.

Efficient Zero-Sequence Impedance Measurement in Autotransformers Using Low-Voltage Excitation

“…The test requires a three-phase power supply to be applied to the low-voltage side, with the low-voltage side A-phase winding being open circuited, while the high-voltage side winding is short circuited to earth in three phases. The composite sequential network is shown in Figure 5, and corresponding zero-sequence impedance is shown in Equation (1). Equations ( 4) and ( 5) also apply to the low-voltage side of a phase disconnection test.…”

“…Power transformers are power equipment for transmitting electrical energy in power systems. In ultra-high-voltage, high-capacity grids of 220 kV and above, the main transformers used include ordinary conventional transformers and autotransformers; the characteristics of both transformers are shown in Table 1 [1,2]. Autotransformers are widely used because of their small size, low cost, large-capacity, high operating efficiency and high short circuit resistance.…”