Latency Determination in Substation Networks Using PTP
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Solution Overview
Problem
Current substation networks face challenges in accurately determining latency due to the limitations of existing time synchronization methods, such as GPS and IRIG-B, which are costly and lack scalability, and packet switched WANs that do not provide synchronous mechanisms, resulting in inadequate accuracy for applications requiring sub-microsecond synchronization.
Innovation Solution
The implementation of a method using the Precision Time Protocol (PTP) standardized in IEEE 1588, which enables latency determination by acquiring and transmitting data values with timestamps through a substation network, allowing for the calculation of residence time and link latency without the need for GPS clocks, and utilizing existing transparent clocks and hardware in network switches and routers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS or IRIG-B time synchronization methods are used, then time synchronization accuracy is improved, but device complexity and deployment cost increase
Solution Approach 1:
The patent uses PTP messages to copy and transfer timing information between devices over the network, replacing the need for dedicated GPS antennas and IRIG-B hardware interfaces. Each device obtains time synchronization information through standard network communication rather than specialized hardware
Solution Approach 2:
The patent replaces mechanical and hardware-based time synchronization systems (GPS antennas, IRIG-B interfaces) with a software-based network protocol solution. The timing function is migrated from dedicated hardware to network software layers, eliminating complex physical infrastructure
2Stability of the object's composition
If TDM networks are used, then synchronous communication is achieved, but adaptability to modern Ethernet networks is reduced
Solution Approach 1:
The patent makes the PTP protocol universal by enabling it to operate over standard Ethernet networks while maintaining synchronous communication capabilities. The protocol can carry both timing information and protection application data, serving multiple functions through a single standardized mechanism that works with modern network infrastructure
Solution Approach 2:
The patent changes the communication medium parameter from dedicated TDM networks to standard Ethernet packet-switched networks. By modifying how timing information is encapsulated and transmitted (using PTP messages over Ethernet frames), the system adapts to modern network parameters while preserving synchronous performance through protocol-level synchronization mechanisms
3Adaptability or versatility
If packet switched WANs are used, then network flexibility and cost are improved, but latency determination accuracy deteriorates
Solution Approach 1:
The patent performs preliminary actions by having relay devices proactively measure and calculate residence time for each PTP message before forwarding it. Devices pre-compute latency values and include them in subsequent messages, enabling accurate latency determination throughout the network path rather than attempting to measure it retrospectively
Solution Approach 2:
The patent implements feedback mechanisms where PTP messages carry timing information and latency measurements back through the network path. Each relay device feeds back its residence time measurement to upstream devices, creating a closed-loop system that continuously refines latency determination accuracy based on actual network conditions
Data Source
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AI summary
The present disclosure relates to latency determination in a substation network. One aspect relates to a method being performed in a first electronic device of the substation network. Another aspect relates to a method being performed in a relay device of the substation network. Yet another aspect relates to a method being performed in a second electronic device of the substation network. Latency is determined using a precision time protocol, such as the IEEE 1588v2 protocol. However, no GPS based master clock timing is required. Instead at least one data value is included as payload in a message of the precision time protocol. The relay device adds a residence time duration and a link latency to the message. The message is then forwarded to the second electronic device. A corresponding first electronic device, relay device, and second electronic device as well as a computer program and computer program product are also provided.