Radio Link Time Synchronization for Remote IEDs
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Solution Overview
Problem
Existing time synchronization methods for intelligent electronic devices (IEDs) in power systems, such as those using SONET, PTP, GPS, and NTP, often require wired connections and are not suitable for remote locations without access to wired infrastructure, and they may not provide the necessary accuracy for applications like synchrophasor calculations.
Innovation Solution
The use of wireless radio links for time synchronization between IEDs, where a master IED determines and compensates for propagation and processing delays to transmit an adjusted time signal to remote IEDs, allowing for synchronization with sub-millisecond accuracy, and utilizing a radio link as a secondary time source in case of primary source unavailability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wireless radio links are used for time synchronization, then IEDs in remote locations without wired infrastructure can be synchronized, but synchronization accuracy may be reduced due to propagation and processing delays
Solution Approach 1:
The master IED performs preliminary measurements of propagation delay between itself and remote IEDs before actual time synchronization. These preliminary delay measurements are stored and used to pre-compensate the time signals transmitted to remote IEDs, thereby eliminating the adverse effect of propagation delay on synchronization accuracy
Solution Approach 2:
The system implements feedback by having remote IEDs measure and report their processing delays and reception times back to the master IED. The master IED uses this feedback information to calculate accurate propagation delays and adjust future time signal transmissions accordingly, continuously improving synchronization precision
2Measurement precision
If propagation delay compensation is implemented, then synchronization accuracy is improved, but system complexity increases due to additional measurement and calculation requirements
Solution Approach 1:
Each IED (both master and remote) performs self-measurement of its own processing delay using its local clock and internal timing mechanisms. The remote IED autonomously measures the time between receiving the time signal and generating its response, eliminating the need for external measurement equipment and reducing overall system complexity
Solution Approach 2:
The system combines multiple functions into the existing time synchronization protocol: time signal transmission, delay measurement, delay compensation calculation, and synchronization verification are all integrated into a single communication exchange between master and remote IEDs, reducing the need for separate measurement systems
3Measurement precision
If sub-millisecond synchronization accuracy is achieved, then synchrophasor calculations and precise monitoring functions are enabled, but more sophisticated delay compensation algorithms are required
Solution Approach 1:
The master IED performs preliminary propagation delay measurements and calculations before actual synchrophasor data collection. These pre-calculated delay values are stored and applied to compensate the time signals, enabling sub-millisecond synchronization accuracy without requiring complex real-time compensation algorithms during critical measurements
Solution Approach 2:
The system applies delay compensation specifically to the critical time synchronization signals used for synchrophasor calculations, while using simpler compensation for other less time-critical communications. This selective application of sophisticated algorithms only where needed maintains accuracy while reducing overall computational complexity
Data Source
AI summary
The present disclosure provides systems and methods for synchronizing the time signals of master and remote IEDs using a radio link. According to one embodiment, a master IED may transmit an adjusted time signal to a remote IED via a radio signal. The master IED may determine a propagation delay between the master IED and a remote IED. The master IED may then adjust a master time signal by the propagation delay and transmit the adjusted time signal to the remote IED. Alternatively, a remote IED may request and receive a master time signal from a master IED via a radio signal. The remote IED may then determine the propagation delay and adjust the received master time signal accordingly. According to various embodiments, the time signal of a master and remote IED may be synchronized to within at least one millisecond.