24-Pulse Autotransformer System for Harmonic Distortion Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing autotransformer systems face challenges in reducing total harmonic distortion (THD) input currents, particularly the third harmonic, without using costly and bulky zero sequence blocking transformers, which increase heat dissipation and maintenance costs.
Innovation Solution
A 24-pulse autotransformer system is configured with two three-phase autotransformers in a reverse phase sequence configuration, coupled with rectifier units, and the turn ratios of the windings are adjusted to decrease voltages, thereby reducing THD without the need for zero sequence blocking transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If zero sequence blocking transformers are used to reduce THD, then total harmonic distortion is reduced, but system cost increases and heat dissipation increases
Solution Approach 1:
The patent extracts and eliminates the zero sequence blocking transformer from the system by using a 24-pulse rectifier configuration with two 12-pulse rectifiers. This configuration naturally blocks zero sequence currents through its inherent circuit topology, removing the need for separate blocking transformers and their associated heat dissipation issues.
Solution Approach 2:
The patent combines the THD reduction function and zero sequence blocking function into the rectifier circuit configuration itself. The 24-pulse rectifier system integrates multiple transformer windings and rectifier bridges in a unified structure that simultaneously achieves harmonic reduction and zero sequence current blocking without requiring additional separate components.
2Object-generated harmful factors
If zero sequence blocking transformers are used to reduce THD, then total harmonic distortion is reduced, but system cost increases
Solution Approach 1:
The patent removes the zero sequence blocking transformer component from the system by implementing a 24-pulse rectifier configuration that inherently blocks zero sequence currents. This extraction eliminates the additional expense associated with purchasing, installing, and maintaining separate blocking transformers while achieving the same THD reduction goal.
Solution Approach 2:
The rectifier circuit configuration serves multiple functions simultaneously: it performs power conversion, reduces total harmonic distortion, and blocks zero sequence currents. This multi-functionality eliminates the need for separate dedicated blocking transformers, thereby reducing system cost while maintaining comprehensive performance.
3Object-generated harmful factors
If zero sequence blocking transformers are used to reduce THD, then total harmonic distortion is reduced, but maintenance requirements increase
Solution Approach 1:
The patent extracts the zero sequence blocking transformer from the system and replaces it with a 24-pulse rectifier configuration that provides inherent zero sequence current blocking. This removal eliminates the maintenance burden associated with additional transformer components, reducing overall maintenance requirements while maintaining THD reduction effectiveness.
4Object-generated harmful factors
If zero sequence blocking transformers are used to reduce THD, then total harmonic distortion is reduced, but space requirements increase
Solution Approach 1:
The patent removes the zero sequence blocking transformer from the system by implementing a 24-pulse rectifier configuration that inherently blocks zero sequence currents. This extraction eliminates the additional physical space required for separate blocking transformers, reducing overall system footprint while achieving the same harmonic reduction performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces THD input currents to comply with standards, enhancing system durability, reducing maintenance, and lowering costs while maintaining market appeal by eliminating the need for additional transformers.
Implementation Method 1
a first three-phase autotransformer coupled to an AC power source, with the first autotransformer having three input terminals and six output terminals
Data Source
Figure 1
Figure 2
Figure 3
AI summary
There is disclosed an apparatus and method to reduce total harmonic distortion input into a 24 -pulse autotransformer system and the autotransformer system itself. The 24 -pulse autotransformer system is configured to receive an input of a first voltage and produce an output voltage of a second voltage. The system includes a pair of autotransformers coupled to an AC power source. One winding of each phase of the first autotransformer has a turn ratio to effect a decrease in the voltage across said winding over a symmetric voltage value and a second winding of each phase of the first autotransformer has a turn ratio to effect a decrease in the voltage across said winding over a symmetric voltage value, thereby reducing total harmonic distortion (THD) in the input current to the system without a zero sequence blocking transformer.