Power Converter Cell Command Merging for Overcurrent Protection
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Solution Overview
Problem
Existing power conversion devices, such as the Modular Multilevel Converter, face complexity in quickly transmitting stop commands to converter cells during overcurrent detection, requiring signal frame switching and error processing, which complicates the transmission process.
Innovation Solution
A power conversion device that combines control and protection information into a single command frame, allowing for quick transmission of stop commands to converter cells by using a control-and-protection command generator that outputs a unified signal regardless of overcurrent detection, simplifying signal processing and maintaining a consistent frame structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate operation command frames and stop command frames are used, then control and protection functions are achieved, but signal processing complexity increases and transmission speed decreases
Solution Approach 1:
The patent combines control information and protection information into a single unified command frame structure. The control command includes both operational control data and protection status data, eliminating the need for separate operation and stop command frames. This merging reduces signal processing complexity while maintaining reliable protection functionality, as the converter cell controller can extract both control and protection information from the same received frame.
2Reliability
If frame switching is performed upon overcurrent detection, then stop commands are transmitted, but transmission time increases due to processing overhead
Solution Approach 1:
The command frame is pre-configured with both control and protection information fields before transmission. The protection information is prepared in advance within the frame structure, so when overcurrent occurs, the controller only needs to modify the protection status field and transmit the frame immediately, rather than switching between different frame types. This preliminary preparation of the frame structure eliminates processing delays during fault conditions.
3Reliability
If error detection and confirmation processes are implemented, then signal reliability is improved, but processing time and complexity increase
Solution Approach 1:
The command frame includes dedicated protection information fields that provide feedback status about system conditions. The converter cell controller continuously monitors these feedback fields to detect overcurrent and other fault conditions. This structured feedback mechanism ensures signal reliability through clear status indication without requiring complex error detection algorithms, as the protection status is explicitly provided in the frame data.
Data Source
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AI summary
A power conversion device (1) in one embodiment includes power conversion circuitry (2) having a plurality of converter cells (7) connected in series to each other. Each converter cell (7) includes an energy storage device (24) and is configured to be capable of discharging stored energy. A control device (30) is configured to generate a control command (33) for controlling operation of each converter cell (7). A protection device (31) is configured to generate a protection command (34) for instructing whether to cause each converter cell (7) to operate based on the control command (33) or to stop operation of each converter cell (7) regardless of the control command (33). A repeating device (32) is configured to generate a control-and-protection command (15) that is a combination of control information based on the control command (33) and protection information based on the protection command (34), and output the generated control-and-protection command (15) to each converter cell (7).