IED Priority Time Sync for Process Bus Traffic
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Solution Overview
Problem
In power system protection systems with multiple IEDs and merging units connected via a process bus, achieving accurate time synchronization while managing increased traffic on the transmission path is challenging, especially when GPS signals are lost, leading to potential failures in data transmission and increased costs.
Innovation Solution
Implementing a priority-based system where IEDs with predetermined priorities output time synchronization signals, ensuring only one signal is transmitted on the process bus, and automatically switching to the next highest priority IED if the primary source fails, thus maintaining accurate synchronization without excessive traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each IED outputs time synchronization signals based on GPS signals, then time synchronization accuracy among MUs is improved, but traffic on the process bus increases excessively
Solution Approach 1:
The patent segments the time synchronization signal transmission function by introducing priority levels among multiple IEDs. Only the IED with the highest priority (lowest priority value) transmits time synchronization signals to the process bus, while other IEDs with lower priorities suppress their transmission. This segmentation resolves the contradiction by allowing accurate time synchronization to be maintained through a single dominant signal source, thereby preventing excessive traffic volume on the process bus.
2Quantity of substance
If a single IED is designated to output time synchronization signals, then traffic on the process bus is reduced, but system reliability decreases if that IED fails
Solution Approach 1:
The patent implements preliminary action by pre-configuring priority values for each IED before any failure occurs. Each IED is assigned a predetermined priority value, and the system is designed so that when the current highest-priority IED fails, the next IED in the priority sequence automatically takes over signal transmission without requiring complex real-time negotiation or reconfiguration. This preliminary arrangement ensures both reduced traffic volume (through single-source transmission) and maintained reliability (through automatic failover capability).
Solution Approach 2:
The system incorporates feedback mechanisms where each IED continuously monitors the presence and validity of time synchronization signals from higher-priority IEDs. When an IED detects that the current signal source has failed or stopped transmitting, it uses this feedback information to determine whether it should activate its own signal transmission based on its priority level. This feedback loop ensures reliable automatic switching while maintaining controlled traffic volume on the process bus.
3Reliability
If multiple IEDs transmit time synchronization signals simultaneously, then system reliability is improved through redundancy, but data transmission failures occur due to process bus overload
Solution Approach 1:
The patent applies dynamics by making the time synchronization signal transmission status of each IED dynamic rather than static. Each IED's transmission behavior changes based on real-time system conditions: when higher-priority IEDs are functioning, lower-priority IEDs suppress transmission; when higher-priority IEDs fail, lower-priority IEDs automatically activate transmission. This dynamic adjustment ensures system reliability through automatic redundancy activation while preventing process bus overload by ensuring only one IED transmits at any given time, thus maintaining high data transmission efficiency.
Data Source
AI summary
A process bus-applied protection system includes a process bus, a plurality of MUs (merging units), and a plurality of IEDs (intelligent electric devices). Each of the MUs is configured to sample a current and a voltage of a power system at timing synchronized with a time synchronization signal received through the process bus. Each of the IEDs is configured to be capable of outputting the time synchronization signal to the process bus by serving as a transmission source, and receiving, through the process bus, the time synchronization signal from another IED. The plurality of IEDs have a predetermined priority. Each of the IEDs is configured, when the IED does not receive the time synchronization signal from an IED having a higher priority than that of the IED and serving as a transmission source, to output the time synchronization signal to the process bus by serving as a transmission source.