Induction Generator Rotor Frequency Control for Grid Deviations
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Solution Overview
Problem
Existing induction generators and converters in wind turbines are over-specified and over-dimensioned to handle frequency deviations from the nominal grid frequency, leading to increased costs, equipment weight, and potential overheating or damage during frequency events.
Innovation Solution
A method and arrangement that control the rotor windings of induction generators by adjusting the rotor winding reference frequency based on the actual grid frequency, using a converter to maintain a constant slip and power output, thereby avoiding over-dimensioning and overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If induction generators and converters are over-dimensioned to handle frequency deviations, then operation reliability across frequency range is improved, but equipment cost and weight increase
Solution Approach 1:
The patent implements dynamic adaptation of the rotor winding reference frequency based on actual grid frequency measurements. The control system continuously adjusts the reference frequency to match grid conditions, allowing the generator to operate reliably across a wide frequency range without requiring oversized components. This dynamic control enables standard-rated equipment to handle frequency deviations that would otherwise require over-dimensioning.
2Reliability
If induction generators and converters are over-dimensioned to handle frequency deviations, then operation reliability across frequency range is improved, but equipment cost increases
Solution Approach 1:
The patent changes the operational parameters of the induction generator by dynamically adjusting the rotor winding reference frequency according to actual grid frequency. This parameter adaptation allows standard-rated generators and converters to operate efficiently across varying frequency conditions, eliminating the need for expensive over-dimensioned equipment while maintaining reliability during frequency events.
3Temperature
If rotor winding reference frequency is adjusted based on actual grid frequency, then equipment overheating is prevented, but control complexity increases
Solution Approach 1:
The control system implements feedback by continuously measuring the actual grid frequency and using this information to adjust the rotor winding reference frequency. This closed-loop control prevents equipment overheating during frequency events while maintaining manageable complexity through a straightforward feedback mechanism that adapts operating parameters based on real-time grid conditions.
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 approach ensures stable operation of induction generators across varying grid frequencies, reducing equipment costs, weight, and preventing overheating, while maintaining connection to the grid as required by regulations.
Implementation Method 1
induction generator connected to a utility grid... controlling rotor windings of the generator by a rotor control signal
Data Source
AI summary
It is described a method of controlling an induction generator (3) connected to a utility grid (47), the method comprising: receiving an actual grid frequency (f); and controlling rotor windings (15) of the generator (3) by a rotor control signal (25a,b,c) having a rotor winding reference frequency (Ω_ref) being set in dependence of the actual grid frequency (f).