Transformer Assembly Using a Single-Core PST at High Line Voltage

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Solution Overview

Problem

Existing phase shifting transformers face limitations in handling high line voltages, are prone to damage during short-circuits, and are not cost-effective, especially when used at voltages above 245 kV, requiring two-core configurations that increase maintenance and operational costs.

Innovation Solution

A transformer assembly comprising a step-up transformer, a step-down transformer, and a single-core phase shifting transformer with delta-connected excitation windings, where the phase shifting transformer is intercalated between the step-down and step-up transformers, allowing for adjustable voltage and reduced impedance, thus eliminating the need for additional short-circuit protection and reducing footprint and costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single-core phase shifting transformer with delta connected excitation windings is used, then the device complexity and cost are reduced, but the transformer undergoes damages during short-circuit due to very low impedance around zero phase shift position

Engineering Contradiction:

Improvetransformer configurationVSAvoidshort-circuit withstand capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

An intermediary device (short-circuit protection device) is introduced between the single-core phase shifting transformer and the transmission line to protect the transformer from short-circuit damage. This allows the use of the simpler single-core configuration while maintaining reliability during fault conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a two-core configuration is adopted for high line voltages above 245 kV, then the transformer can withstand short-circuits and operate at higher voltages, but the footprint and operation and maintenance costs increase

Engineering Contradiction:

Improveshort-circuit withstand capabilityVSAvoidfootprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The system is segmented into three functional parts: a step-down transformer, a single-core phase shifting transformer, and a step-up transformer. This segmentation allows each component to be optimized independently, enabling the use of a compact single-core PST while the step-up/step-down transformers handle the high voltage and short-circuit requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite transformer assembly by combining different transformer types (step-down, phase shifting, step-up) with different functions. This composite structure achieves the benefits of both single-core (compactness) and two-core (short-circuit capability) configurations.

Inventive Principle:

Principle #40Composite materials

3Reliability

If a two-core symmetrical design PST is used for higher line voltages, then the transformer can operate at voltages above 245 kV and withstand short circuits, but the operation and maintenance costs increase

Engineering Contradiction:

Improveshort-circuit withstand capabilityVSAvoidoperation and maintenance cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system is segmented into three functional parts: a step-down transformer, a single-core phase shifting transformer, and a step-up transformer. This segmentation allows each component to be optimized independently, enabling the use of a simpler single-core PST while the step-up/step-down transformers handle the high voltage and short-circuit requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The step-up and step-down transformers serve multiple functions: voltage transformation, short-circuit protection, and enabling the use of a single-core PST. This multi-functionality reduces the need for a more complex two-core PST configuration.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Area of stationary object

If a single-core PST with delta connected excitation windings is used, then the footprint and cost are reduced, but additional short-circuit protection is required

Engineering Contradiction:

ImprovefootprintVSAvoidshort-circuit protection requirement

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The solution enables operation at high line voltages without additional short-circuit protection, reduces operational and maintenance costs, and maintains a compact footprint, making it a more flexible and cost-effective alternative to existing phase shifting transformers.

Implementation Method 1

a phase shifting transformer (40) having a source side and a load side connected, respectively, to the step-down transformer and the step-up transformer

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a phase shifting transformer (40) having a source side and a load side connected, respectively, to the step-down transformer and the step-up transformer

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS20230282413A1Power transformer assembly

Publication Date: 2023.09.07 GE VERNOVA INFRASTRUCTURE TECHNOLOGY LLC

AI summary

The present application concerns a transformer assembly. The transformer assembly includes a step-up transformer, a step-down transformer, and a phase shifting transformer having a source side and a load side connected, respectively, to the step-down transformer and the step-up transformer.