Transmission Line Relay Backup Terminal Switching
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Solution Overview
Problem
Existing transmission line protective relay devices face challenges in maintaining reliability and reducing equipment costs, particularly in systems with three or more terminals, where communication failures can lead to delayed information arrival and increased processing complexity, and duplicating transmissions to enhance reliability results in higher costs.
Innovation Solution
A transmission line protective relay device that performs fault evaluation by mutual exchange of terminal information through communication channels, using current difference computation and directional comparative distance relay methods, with a mechanism to switch to backup terminal information if main information cannot be received within a predetermined time, ensuring continued operation even during communication malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If terminal information is transmitted through communication channels in multi-terminal systems, then fault detection capability is improved, but communication failures cause information arrival delays and reduce reliability
Solution Approach 1:
The patent pre-calculates and stores backup terminal information along with its validity flag before communication failures occur. This preliminary preparation ensures that when communication failures happen, the relay device can immediately switch to using pre-validated backup information without delay, thus maintaining both fault detection capability and reliability.
Solution Approach 2:
The patent prepares backup terminal information in advance as a cushion against potential communication failures. By storing multiple sources of terminal information with validity flags that indicate their current usability, the system creates a safety buffer that prevents communication failures from impacting fault detection reliability.
2Reliability
If backup terminal information is stored and validity flags are used, then information reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the validity flag automatically indicates whether terminal information can be used without requiring complex external validation processes. This simple binary flag system allows the relay device to autonomously determine information usability, reducing processing complexity while maintaining high reliability.
Solution Approach 2:
The patent extracts only the essential validity flag information from complex communication status data, separating the critical usability indicator from other unnecessary details. This extraction approach simplifies the processing logic by focusing only on whether backup information is valid, rather than analyzing entire communication protocols.
3Measurement precision
If current differential relay methods are used, then fault detection accuracy is improved, but equipment costs increase for multi-terminal systems
Solution Approach 1:
The patent makes the terminal information storage structure universal by designing it to handle both primary and backup information from any number of terminals through a standardized validity flag mechanism. This multi-functional design allows the same hardware structure to serve multiple terminals without requiring additional specialized equipment for each terminal, thereby reducing overall equipment costs while maintaining high fault detection accuracy.
Data Source
AI summary
In a protective relay device for a three-terminal transmission line comprising terminal A, terminal B and terminal C, when for example terminal information is transmitted to a protective relay Ry-A of one remote terminal (terminal A) from the protective relay Ry-C of the terminal C, terminal information Db that was sent from the protective relay Ry-B of another remote terminal (terminal B) is transmitted, in addition to the information Dc of the terminal in question. In the same way, when terminal information is transmitted to a protective relay Ry-B of the terminal B from the protective relay Ry-C of the terminal C, terminal information Da that was sent from the protective relay Ry-A of the terminal A is transmitted, in addition to the information Dc of the terminal in question.