Solid-State Stator Switch for Doubly-Fed Induction Generator Wind Turbines

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Solution Overview

Problem

Existing doubly fed induction generator (DFIG) wind turbine systems rely on mechanical stator switches, which are expensive, prone to failure, and have limited operational life due to moving parts, necessitating a more reliable and efficient switching solution.

Innovation Solution

The implementation of a solid-state switch, specifically a three-phase switch with silicon-controlled rectifier (SCR) assemblies in a back-to-back arrangement, coupled between the stator bus and transformer, replacing mechanical switches and utilizing a gate drive circuit for control, including zero-crossing control to minimize power transients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical stator switch is used to provide grid isolation, then the system can achieve electrical disconnection during critical periods, but the switch is prone to failure due to moving parts and has limited operational life

Engineering Contradiction:

Improveswitch reliabilityVSAvoidoperational life of switch

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the mechanical stator switch with a solid-state switch assembly that uses semiconductor devices (IGBTs or MOSFETs) instead of mechanical moving parts. This substitution eliminates wear and tear associated with mechanical components, thereby improving reliability and extending operational life while maintaining the grid isolation function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a solid-state switch assembly as an intermediary device between the stator bus and the transformer. This assembly provides the necessary electrical connection or disconnection function without relying on mechanical moving parts, thus resolving the reliability and lifespan issues of traditional mechanical switches.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a mechanical stator switch is used, then grid isolation can be achieved, but the switch is expensive to purchase and operate

Engineering Contradiction:

Improvegrid isolation capabilityVSAvoidcost of switch

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive mechanical switches with solid-state semiconductor-based switch assemblies. Solid-state devices generally have lower manufacturing costs, reduced maintenance requirements, and longer service lives, thereby reducing the overall cost of ownership while maintaining grid isolation capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If a mechanical stator switch is used, then switching can be performed, but time delays occur in the switching process

Engineering Contradiction:

Improveswitching capabilityVSAvoidswitching time delay

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent replaces mechanical switching mechanisms with solid-state semiconductor switches that can be controlled electronically. Solid-state switches respond almost instantaneously to control signals, eliminating the mechanical response time delays inherent in traditional switches, thereby improving switching speed and reducing time losses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If a mechanical stator switch is used, then the system can operate, but the switch is prone to failure during service

Engineering Contradiction:

Improveswitch operationVSAvoidfailure risk

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces mechanical switches with solid-state switch assemblies that have no moving parts. This substitution eliminates the wear, friction, and mechanical failure modes that plague traditional switches, thereby significantly reducing failure risk during service while maintaining full operational capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solid-state switch enhances operational lifespan, reduces failure risk, increases efficiency, and eliminates time delays in switching, providing reliable grid isolation during critical periods with reduced risk of power transients.

Implementation Method 1

a three-phase solid-state switch coupled between the stator bus and the transformer, each phase of the switch including at least one silicon-controlled rectifier (SCR) assembly

Methodology Applied

Scientific EffectRectification: Diode

Data Source

PatentUS9018783B2Doubly-fed induction generator wind turbine system having solid-state stator switch

Publication Date: 2015.04.28 GE INFRASTRUCTURE TECH LLC

AI summary

Wind turbine systems and methods are provided. An exemplary system includes a wind driven doubly fed induction generator having a rotor and a stator, the stator providing AC power to a stator bus. The system further includes a power converter coupled to the rotor of the doubly fed induction generator, the power converter providing an output to a line bus, and a transformer coupled to the stator bus. The system further includes a solid-state switch coupled between the stator bus and the transformer.