Grandmaster Timing Unit Synchronization in Substation Networks
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Solution Overview
Problem
In electrical power substations, the switching of the grandmaster role between time indication units in the Precision Time Protocol (PTP) can lead to time jumps and blockage of protection functions due to unsynchronized local oscillators, causing unintentional power supply interruptions.
Innovation Solution
A restored or reconnected grandmaster-capable timing unit first synchronizes its internal oscillator with the current grandmaster before assuming the grandmaster role, avoiding immediate role switching and ensuring continuous synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a restored grandmaster-capable timing unit immediately assumes the grandmaster role upon reconnection, then the timing unit can quickly restore its synchronization function, but time jumps occur and protection functions are blocked due to unsynchronized local oscillators
Solution Approach 1:
The patent applies preliminary action by requiring the timing unit to synchronize its local oscillator with the current grandmaster's time signal before assuming the grandmaster role. This preparatory synchronization step ensures that when the timing unit transitions to grandmaster, its oscillator is already aligned with the network time reference, preventing time jumps and ensuring continuous protection function operation.
2Measurement precision
If satellite-based global reference clock sources (GNSS) are used, then absolute time values can be provided for synchronization, but the system becomes susceptible to interference from jamming or spoofing
Solution Approach 1:
The patent extracts the system from dependence on external satellite-based GNSS references by implementing a fully autonomous oscillator-based synchronization mechanism. The timing units use their internal oscillators to generate and maintain time references without requiring external satellite signals, thereby eliminating susceptibility to jamming or spoofing while maintaining sufficient synchronization accuracy for substation protection functions.
3Extent of automation
If the Best Master Clock Algorithm (BMCA) is used to automatically select the grandmaster, then the system achieves automatic role assignment, but time jumps occur when oscillators are not mutually synchronized
Solution Approach 1:
The patent modifies the automatic BMCA process by adding a preliminary synchronization step. Before a timing unit can assume the grandmaster role through BMCA, it must first synchronize its local oscillator with the current grandmaster's time signal. This ensures that the automatic role assignment does not result in time jumps, as the transitioning unit's oscillator is already aligned with the network time reference.
Data Source
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AI summary
The invention relates to a method for synchronizing intelligent electronic devices (IEDs) (5) in a locally confined network (1), wherein the locally confined network (1) has at least two time units (2, 3), wherein: - for a functioning or reconnected time unit (2), it is checked whether there is another time unit (3) in the network that assumes an active grandmaster role (1), - the first time unit (2) is forced into its slave state if another time unit in the grandmaster role has been detected in the locally confined network (1), wherein the first time unit (2) synchronizes with the time unit (3) in the grandmaster role, - after synchronization, the enforcement of the slave state for the first time unit (2) is lifted, - the first time unit (2) switches to the role of the grandmaster time unit.if it is better suited for the grandmaster role, or remains in its slave state if another time unit (3) in the network (1) is better suited for the grandmaster role.