Inter-Substation Sample Synchronization Without GPS Clock Dependence
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Solution Overview
Problem
Current time synchronization methods for substations, such as those using GPS clocks or IEEE1588, are vulnerable to weather conditions and non-constant transmission delays, necessitating improved mechanisms for maintaining accurate time references across different substations.
Innovation Solution
A method for time-synchronized communication between substations involves receiving packets with time information from a common reference clock, compensating for time differences between local and common reference clocks, and synchronizing samples to enable efficient operation of line differential protection functions without relying on a single common time reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS based clocks are used for time synchronization, then a common time reference is achieved, but sensitivity to bad weather conditions and spoofing increases
Solution Approach 1:
The patent introduces a common reference clock as an intermediary time source that is not GPS-based. This reference clock receives time information from GPS but processes and distributes it independently, acting as a mediator between GPS and the measurement devices. This eliminates direct dependency on GPS signals while maintaining time reference accuracy, thereby resolving the contradiction between precision and reliability.
2Device complexity
If a single common reference clock is used for all substations, then time synchronization is simplified, but vulnerability to single point of failure increases
Solution Approach 1:
The patent segments the time reference system by allowing each substation to have its own local reference clock while still maintaining synchronization through the common reference clock. This segmentation eliminates the single point of failure risk associated with a centralized clock while keeping the synchronization mechanism relatively simple through the use of time information packets.
3Ease of manufacture
If existing substations with less accurate time synchronization are used, then infrastructure costs are reduced, but time synchronization accuracy between substations deteriorates
Solution Approach 1:
The patent changes the parameter of time reference by introducing a common reference clock that provides absolute time information. This allows existing substations with less accurate local clocks to achieve accurate inter-substation synchronization by referencing the common time source, without requiring hardware upgrades. The parameter change from local relative time to common absolute time resolves the contradiction between cost and accuracy.
Data Source
AI summary
There is provided mechanisms for time-synchronized communication of packets between a first substation and a second substation interconnected by a communication channel. Samples obtained within the second substation are provided with time information associated with a common reference clock and sent to the first substation, at which a time-wise synchronization of the received samples with samples obtained within the first substation is performed by means of the time information and a time difference between the common reference clock and a local reference clock of the first substation.