Differential Protection for Multi-Terminal T-Connection Lines
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Solution Overview
Problem
In multi-terminal T-connection transmission lines, existing differential protection methods face challenges in accurately detecting inconsistent transceiving delays across channels, which hinders effective protection.
Innovation Solution
A method and system that connect a host to multiple slaves, forming a slave group by selecting two unconnected slaves, where one slave acts as a target and another as an auxiliary, using separate communication paths to measure and compare transceiving delays, triggering alarms or entering protection mode based on preset differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sampling time adjustment method is used in multi-terminal T-connection transmission lines, then the differential protection can be implemented, but it is difficult to detect inconsistent transceiving delays of any channel
Solution Approach 1:
The system segments the communication channels into multiple independent paths (first communication path through channel 1, second communication path through channel 2) to enable separate delay measurement for each channel. This segmentation allows the differential protection system to detect transceiving delay inconsistencies by comparing delays of different channels independently.
Solution Approach 2:
The system changes the measurement parameter by introducing explicit delay measurement mechanisms. Each channel's transceiving delay is measured by recording timestamps at the host and slave devices, then calculating the delay based on these timestamps. This parameter change enables precise detection of delay inconsistencies that were previously undetectable.
2Reliability
If multiple communication channels are used for differential protection, then the protection coverage is improved, but the difficulty of detecting and measuring transceiving delays increases
Solution Approach 1:
The system implements feedback by having the slave device send back acknowledgment messages to the host after receiving protection data. The host records the reception timestamp, and the delay is calculated based on the round-trip time and known transmission intervals. This feedback mechanism provides a reliable way to measure transceiving delays in multi-channel differential protection systems.
Solution Approach 2:
The system performs preliminary action by pre-configuring multiple communication channels and establishing their connectivity before differential protection operation. The host and slave devices pre-record their clock information and channel characteristics, enabling accurate delay measurement when protection events occur.
Data Source
AI summary
Provided are a differential protection method and system, applied to a multi-terminal T-connection transmission line. The method includes: selecting two slaves without a connection and connecting the two slaves to construct a slave group; determining a target slave and an auxiliary slave in the slave group, where a first communication path is connected along a channel one, a channel two and a channel three, and a second communication path is connected along the channel three, the channel two and the channel one; transmitting, by the target slave, two frames of messages, and acquiring a delay difference between a transceiving delay of the first communication path and a transceiving delay of the second communication path, where a first frame of messages is transmitted to the target slave via the first communication path, a second frame of messages is transmitted to the target slave via the second communication path.