DC Link Voltage Control for Wind Turbine Power Converters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wind turbines face challenges in maximizing DC link voltage while minimizing losses and ensuring robustness against grid events and maintaining power switching device reliability.
Innovation Solution
A method that monitors rotor speed and determines line-side and rotor-side voltages to control DC link voltage, expanding the rotor speed operating range and adjusting DC link voltage based on these parameters to optimize energy production and reduce component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the steady state DC link operating voltage set point is set as high as possible to maximize the operating voltage of the DFIG, then the operating voltage is improved, but the robustness against grid events deteriorates and the risk of component failure increases
Solution Approach 1:
The patent applies dynamics by making the DC link voltage set point adjustable and adaptive rather than fixed. The controller dynamically modifies the DC link voltage set point based on operating conditions, allowing it to be higher during normal operation for maximum power extraction and lower during grid events for protection, thus resolving the contradiction between maximizing voltage and maintaining robustness
Solution Approach 2:
The patent changes the parameter of DC link voltage set point from a constant high value to a variable parameter that adapts to different operating conditions. By monitoring grid events and adjusting the voltage set point accordingly, the system achieves both high operating voltage during normal conditions and robustness during abnormal conditions
2Power
If the steady state DC link operating voltage set point is set as high as possible to maximize the operating voltage of the DFIG, then the operating voltage is improved, but the failure rate of switching devices increases
Solution Approach 1:
The system dynamically adjusts the DC link voltage set point based on real-time operating conditions and grid events. During normal operation, the voltage is maintained at a higher level for maximum power extraction, but during abnormal conditions, the voltage is reduced to protect switching devices, thus resolving the contradiction between operating voltage and device reliability
Solution Approach 2:
The patent implements a protective mechanism that anticipates potential overvoltage conditions and takes preventive action by lowering the DC link voltage set point before damage can occur to switching devices. This cushioning approach protects components while allowing optimal operation during normal conditions
3Reliability
If a margin is required between the steady state DC link operating voltage set point and the maximum allowable instantaneous DC link voltage to avoid component failure, then the robustness is improved, but the operating voltage decreases
Solution Approach 1:
The patent eliminates the need for a permanent margin by making the DC link voltage set point dynamic. The system operates at the maximum allowable voltage during normal conditions to maximize power extraction, and only reduces the voltage when necessary to maintain the margin during grid events, thus resolving the contradiction between robustness and operating voltage
Data Source
AI summary
The present subject matter is directed to a system and method for operating an electrical power circuit connected to a power grid. The electrical power circuit has a power converter electrically coupled to a generator. The method includes monitoring a rotor speed of the generator during operation of the electrical power circuit. The method also includes increasing an operating range of the rotor speed of the generator. Further, the method includes determining at least one of a line-side voltage of a line-side converter of the power converter or a rotor-side voltage of a rotor-side converter of the power converter during operation of the electrical power circuit. Another step include controlling, via a converter controller, a DC link voltage of a DC link of the power converter as a function of one or more of the line-side voltage, the rotor-side voltage, and/or the rotor speed.