Synchronizing TDM Data Over Packet Switched Networks
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Solution Overview
Problem
Packet switched data networks introduce variable packet latency and asymmetrical transmission times, making it difficult to synchronize data transmission for line differential protection in electric power systems, which rely on precise timing for detecting faults like short circuits.
Innovation Solution
A method that synchronizes communication modules using time stamps and predefined delays to emulate a circuit switched communication link, ensuring that data is output at a consistent time delay across the network, thereby compensating for packet delay variation and maintaining data synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If packet switched data networks are used for data transmission, then flexibility and cost-effectiveness are improved, but data synchronization and timing precision deteriorate due to variable packet latency
Solution Approach 1:
The system performs preliminary actions by calculating the actual transmission time of each packet before outputting the data. The receiving module determines how long the packet took to traverse the network and proactively adjusts the output timing accordingly, rather than waiting for synchronization issues to arise. This preliminary time calculation and compensation enables precise timing control despite using flexible packet-switched networks.
2Device complexity
If packet switched networks are used, then device complexity is reduced compared to circuit switched networks, but data synchronization becomes more difficult due to variable transmission times
Solution Approach 1:
The system implements feedback by continuously monitoring and calculating actual packet transmission times. The receiving module measures the time difference between when data was sent and when it was received, and uses this feedback information to dynamically adjust output timing. This closed-loop feedback mechanism ensures reliable data synchronization while maintaining the simplicity of packet-switched network infrastructure.
3Reliability
If time stamps and dynamic delay adjustment are implemented, then data synchronization is improved, but processing complexity increases
Solution Approach 1:
The system applies self-service by having each communication module independently calculate and adjust its own timing based on actual transmission measurements. Rather than requiring a complex centralized timing control system, each module autonomously determines its output delay based on the time stamps and measured transmission times. This distributed self-service approach maintains high synchronization reliability while minimizing overall system processing complexity.
Data Source
AI summary
A method for transmitting measurement data 28a comprise the steps of: receiving measurement data 28a in a first communication module 22a; time stamping the measurement data 28a in the first module with a time tag 34; transmitting the measurement data 28a to a second communication module 22b via a packet switched data network 24; and outputting the transmitted measurement data 30a after a predefined delay time ΔtD after the time stamping of the measurement data 28a.