DC Crowbar Controller for Wind Turbine Voltage Regulation
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Solution Overview
Problem
Existing solutions for regulating DC bus voltages during voltage irregularities, such as those in wind turbine generators, are ineffective as they often lead to excessive DC bus voltages causing component damage and wear, particularly due to the use of AC crowbar systems which fail to directly control DC bus voltages effectively.
Innovation Solution
A DC crowbar controller system that directly regulates DC bus voltages by modifying operational characteristics at the DC bus, utilizing a switching device, resistor, and flyback diode to manage voltage irregularities, thereby protecting power converters and reducing transient torques on generator shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AC crowbar is used to regulate DC bus voltage, then the system attempts to control voltage indirectly through AC circuit interaction, but excessive DC bus voltages occur causing component damage and generator wear
Solution Approach 1:
The patent introduces a DC crowbar controller as an intermediary device specifically designed to regulate DC bus voltage. This mediator directly interfaces with the DC bus through a switching device, resistor, and flyback diode, providing dedicated voltage regulation without relying on indirect AC circuit interaction. The DC crowbar controller acts as a specialized intermediary that bridges the gap between the power converter and DC bus, effectively controlling voltage levels and preventing excessive voltages that cause component damage.
Solution Approach 2:
The patent replaces the AC-based mechanical/electrical crowbar system with a DC-based electronic control system. By substituting the AC crowbar mechanism with a DC switching device controlled by a DC crowbar controller, the system achieves more direct and effective voltage regulation. This substitution eliminates the indirect control path through AC circuits and replaces it with direct DC bus voltage management through electronic switching and resistive dissipation.
2Adaptability or versatility
If AC crowbar system is implemented, then voltage control is attempted through AC side modification, but the system complexity increases without effective DC voltage regulation
Solution Approach 1:
The patent extracts the voltage regulation function from the AC crowbar system and creates a separate, dedicated DC crowbar controller. By taking out the DC voltage regulation task from the complex AC control system, the patent creates a simpler, specialized controller that directly manages DC bus voltage. This extraction reduces the burden on the overall power control system while maintaining adaptability to voltage irregularities.
Solution Approach 2:
The patent segments the voltage control function into separate AC and DC control paths. The DC crowbar controller operates independently on the DC side, while the AC side handles generation and conversion. This segmentation allows each subsystem to be optimized for its specific function, reducing overall system complexity while maintaining versatility in handling voltage irregularities.
3Reliability
If direct DC bus voltage regulation is implemented, then component protection is improved, but additional control circuitry is required
Solution Approach 1:
The patent employs a resistor as a disposable energy dissipation element in the DC crowbar controller. During voltage irregularities, the switching device activates the resistor to dissipate excess energy, protecting sensitive power converter components. The resistor serves as a sacrificial, short-living component that can be easily replaced, providing reliable protection without requiring complex, expensive protective circuitry.
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 DC crowbar controller system effectively regulates DC bus voltages during voltage irregularities, preventing component damage and reducing fatigue loads on wind turbine gearboxes by directly managing DC bus voltage, thus ensuring stable operation and extended equipment lifespan.
Implementation Method 1
a flyback diode operatively connected with the switching device, wherein the flyback diode is configured to redirect current flow in response to the switching device switching off
Implementation Method 2
a resistor operatively connected with the switching device, wherein the resistor is configured to dissipate power when the switching device is switched on
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
The disclosure details implementations of apparatuses, methods, and systems for regulating DC bus voltages. In an implementation, the system is configured to regulate the DC bus voltage directly by operating at the DC bus rather than indirectly on the AC side of the DC bus. In one implementation, the DC voltage regulator is configured with components including a DC voltage regulator power control board, a switching device, a resistor, and a flyback diode. In one non-limiting implementation example, the DC voltage regulator may be used to control the DC bus voltage of a doubly fed induction generator of a wind turbine. In this implementation, the DC voltage regulator effectively protects the converter of the induction generator and also reduces the transient torques on the generator shaft during voltage irregularities. This, in turn, reduces excessive wear on the wind turbine gearbox by limiting fatigue loads on the gear teeth that may result from transient torques.