Converter Arm Redundant Control Signal Propagation
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Solution Overview
Problem
Existing high voltage direct current (HVDC) converter systems face challenges in ensuring reliable communication of control signals to converter cells, particularly when the number of cells is large, leading to potential faults and reduced system reliability.
Innovation Solution
A converter arm design with multiple control signal connections between each converter cell and neighboring cells or the main controller, including shortcut connections, allows for redundant signal propagation and quick detection of blocking messages, ensuring that even multiple cell failures do not affect controllability, and includes auxiliary power inputs for testing without main power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each converter cell is connected to receive control signals from multiple entities (main controller and neighboring cells), then fault tolerance is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into multiple independent control entities (main controller and autonomous converter cells). Each converter cell is divided into a control unit that can independently generate and forward control signals, allowing the system to segment control functions across multiple nodes rather than relying on a single centralized controller for all cells.
Solution Approach 2:
Neighboring converter cells act as intermediary nodes in the control signal transmission path. When a control signal needs to reach distant cells, it propagates through intermediate converter cells that forward the signals, eliminating the need for direct connections between the main controller and every individual cell.
2Reliability
If control signals are propagated through multiple converter cells, then coverage is improved, but signal delay increases
Solution Approach 1:
The control signal transmission path is segmented into parallel routes through different neighboring cells. Instead of a single long propagation path, multiple shorter paths are created through the segmented network of converter cells, reducing the maximum delay any single signal experiences.
Solution Approach 2:
Control signals are prepared and forwarded in advance by intermediary converter cells. When a control signal arrives at a converter cell, the control unit immediately forwards it to neighboring cells without waiting for confirmation or additional processing, enabling preliminary action that reduces overall propagation time.
3Measurement precision
If blocking messages are fully decoded before forwarding, then accuracy is improved, but response time deteriorates
Solution Approach 1:
The blocking message detection function is extracted from the full message decoding process. The control unit is designed to specifically detect blocking messages through simplified recognition mechanisms that identify the unique characteristics of blocking messages without requiring complete decoding of the entire message structure.
Solution Approach 2:
Different processing quality is applied to different message types. Blocking messages receive expedited local processing with simplified detection and immediate forwarding, while other control messages undergo complete decoding and verification. This local quality differentiation ensures critical blocking messages are handled with higher speed while maintaining adequate accuracy.
Data Source
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Figure 3~4B
Figure 5~6B
AI summary
It is presented a converter arm for power conversion. The converter arm comprises: a plurality of converter cells, wherein each converter cell comprises a plurality of semiconductor switches, an energy storage element and at least three control signal connections arranged to control the conducting state of the plurality of semiconductor switches. Each converter cell is connected to receive a control signal from at least three entities via said control signal connections, wherein at least two of the three entities are neighbouring converter cells, and each converter cell is arranged to forward a control signal to all connected neighbouring converter cells via said control signal connections. A corresponding converter device is also presented.