Wind Power Converter Control via Virtual Current Feedback
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Solution Overview
Problem
Existing methods for controlling converter systems in wind power installations lack coordination of switching actions, leading to inefficiencies and increased power losses, particularly due to unmanaged circulating currents and network requirements.
Innovation Solution
A method for coordinating the operation of multiple parallel converter modules by superposing their electrical AC currents, detecting the total current, determining a virtual current based on switch positions, and adjusting switch positions to optimize power output and reduce switching losses, utilizing a cascaded closed-loop control system with tolerance bands to ensure efficient load distribution and minimize control deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple converter modules are connected in parallel to increase total power output, then the power output of the converter system is improved, but circulating currents occur within the converter system
Solution Approach 1:
The control device detects the total current of the converter system and determines a virtual current based on switch positions. This feedback mechanism allows the system to monitor and adjust for circulating currents in real-time, preventing their harmful effects while maintaining the parallel configuration for high power output.
Solution Approach 2:
The control device changes switch positions of individual converter modules based on the detected total current and determined virtual current. By dynamically adjusting switching parameters, the system optimizes current distribution among parallel modules, eliminating circulating currents while preserving total power output capability.
2Ease of operation
If switching actions of converter modules are controlled independently, then each module can operate autonomously, but coordination of switching actions beyond module level is lacking
Solution Approach 1:
The control device acts as an intermediary between individual converter modules. It receives switching information from each module, processes the total current and virtual current data, and coordinates switching actions across all modules. This centralized coordination layer enables autonomous module operation while ensuring system-wide optimization.
3Device complexity
If converter modules operate without coordinated switching control, then control is simpler, but switching losses increase and power output is reduced
Solution Approach 1:
The control device dynamically changes switch positions of converter modules based on real-time detection of total current and determination of virtual current. This parameter optimization minimizes switching losses by coordinating switching actions, while the control architecture remains relatively simple through its focus on current-based coordination.
Data Source
AI summary
The present disclosure relates to a method for controlling a converter, in particular power converter of a wind power installation. The converter has a plurality of, preferably parallel, converter modules. The method includes the following steps: driving a first converter module, such that the converter module generates a first electrical AC current in a first switch position, driving a second converter module, such that the converter module generates a second electrical AC current in a second switch position, superposing the first electrical AC current and the second electrical AC current to form a total current, detecting the total current of the converter, determining a virtual current depending on the first and second switch positions, and changing the first switch position of the first converter module and/or the second switch position of the second converter module depending on the total current and the virtual current.