DFIG Wind Turbine Converter SSR Damping Control
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Solution Overview
Problem
Doubly-fed induction generator (DFIG) wind turbine converter systems face challenges in managing sub-synchronous resonance (SSR) events, which can lead to amplified sub-synchronous current components and potential damage due to excessive control responses, as existing control methods fail to effectively dampen these events.
Innovation Solution
The method involves detecting SSR events and switching to an SSR-control mode, which includes freezing rotor AC voltages in magnitude and phase, altering rotor-current-controller gains, and adjusting rotor-current-controller time constants to prevent amplification of sub-synchronous currents, thereby mitigating the impact of SSR events on the converter system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing control methods are used to manage SSR events, then the converter system responds to SSR events, but sub-synchronous current components are amplified and potential damage occurs
Solution Approach 1:
The control system applies preliminary anti-action by detecting SSR events early and switching to SSR-control mode before significant current amplification occurs. The control method preemptively freezes rotor AC voltages and adjusts controller parameters to counteract the harmful amplification effect before it can develop fully, thereby protecting the converter system while maintaining reliability
Solution Approach 2:
The invention applies parameter changes by dynamically altering rotor-current-controller gains and time constants based on detected SSR conditions. The control system modifies these parameters in real-time to dampen sub-synchronous current components, transforming the system's response characteristics to prevent harmful amplification while maintaining stable operation
2Object-generated harmful factors
If rotor AC voltages are frozen in magnitude and phase, then sub-synchronous current amplification is prevented, but control flexibility is reduced
Solution Approach 1:
The control system applies dynamics by implementing a switchable dual-mode control structure. The system can dynamically transition between non-SSR-control mode and SSR-control mode based on detected conditions. In SSR-control mode, rotor AC voltages are frozen to prevent amplification, while in non-SSR mode, full control flexibility is maintained, thus resolving the contradiction between preventing harmful factors and maintaining adaptability
Solution Approach 2:
The invention applies preliminary action by preparing and switching to predefined SSR-control parameters when SSR events are detected. The control system has pre-configured parameter sets for SSR conditions, allowing rapid switching without losing overall control flexibility. This preliminary preparation enables the system to maintain adaptability for different operating conditions while effectively preventing sub-synchronous current amplification when needed
Data Source
AI summary
A method is provided of controlling a doubly fed induction generator—(DFIG) wind turbine converter system if a sub-synchronous resonance event acts on the wind turbine. According to the method a sub-synchronous resonance event is detected. Thereupon, a switch from a non-SSR-control mode to a SSR-control mode is performed. At least one of the following activities is performed in the SSR-control mode, namely: (i) freezing rotor AC voltages in magnitude and phase, (ii) altering at least one rotor-current-controller gain (iii) altering at least one rotor-current-controller time constant, to dampen the effect of the SSR-event on the wind turbine.