DFIG Leakage Inductance Determination via Current Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Estimation errors in leakage inductance values for double fed induction generators lead to inaccurate control and poor performance, especially during Low Voltage RideThrough situations, due to the reliance on manufacturer-provided or user-estimated values that may not match actual machine parameters.
Innovation Solution
A method to automatically determine machine leakage inductances during operation by controlling rotor and stator currents to near zero, allowing for precise calculation of leakage inductances using measured voltage and current values, thereby improving control performance and reducing the need for slow dynamics in higher level controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manufacturer-provided or user-estimated leakage inductance values are used in control, then device complexity is reduced, but control accuracy deteriorates
Solution Approach 1:
The control system automatically determines the leakage inductance values by utilizing measured voltage and current values during generator operation, eliminating the need for external measurement devices or manual parameter input. The system serves itself by extracting parameter information from its own operational data, thereby maintaining simplicity while achieving high accuracy.
2Measurement precision
If higher level control loops are added to compensate for parameter errors, then control accuracy improves, but response time deteriorates
Solution Approach 1:
The leakage inductance values are determined in advance during normal operation before LVRT conditions occur. This preliminary determination ensures that accurate parameter values are available when needed, eliminating the need for slow higher level control loops to compensate for parameter errors during critical transients.
3Measurement precision
If automatic determination of leakage inductances is implemented, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent replaces physical measurement devices (such as impedance analyzers or LCR meters) with an electrical calculation method that uses voltage and current measurements already available from the generator's normal instrumentation. This substitution eliminates the need for additional measurement hardware while achieving accurate parameter determination.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A method and arrangement for determining leakage inductances of a double fed induction generator, DFIG, (10) wherein, in response to the stator current of the DFIG being equal to or below a first predetermined threshold, values of a stator voltage, a rotor voltage and a rotor current of the DFIG are determined, and a rotor leakage inductance of the DFIG is calculated on the basis the determined values, and, in response to the rotor current of the DFIG being equal to or below a second predetermined threshold, values of the stator voltage, the rotor voltage and the stator current of the DFIG are determined, and a stator leakage inductance of the DFIG is calculated on the basis of the determined values.