Double-Circuit Line Fault Location Using Mutual-Coupling Fault Factors
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Solution Overview
Problem
Existing distance protection methods for double-circuit lines connected to inverter-based renewable energy sources (IBRs) face challenges due to mutual coupling effects and varying fault scenarios, leading to unreliable protection and inaccurate fault location.
Innovation Solution
A generic, single-ended, local measurement-based method that uses local voltage and current measurements from both lines to determine fault location, incorporating the effects of mutual coupling and capable of operating with both IBRs and conventional sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If traditional distance protection methods are used for double-circuit lines connected to IBRs, then the protection coverage can be extended to the entire line, but the reliability deteriorates due to mutual coupling effects and varying fault scenarios
Solution Approach 1:
The patent segments the fault detection problem by introducing a fault factor that separately evaluates the contribution of each circuit to the fault. By calculating the fault factor for each circuit independently using local measurements, the method can identify which circuit is faulty without being affected by mutual coupling from the other circuit, thus maintaining high reliability while providing full line coverage.
Solution Approach 2:
The patent introduces a fault factor as an intermediary parameter that mediates between the complex mutual coupling effects and the protection decision. This fault factor, derived from local voltage and current measurements, serves as a reliable indicator that is insensitive to mutual coupling, enabling accurate fault detection and line identification without communication or assumptions about remote system conditions.
2Adaptability or versatility
If existing protection methods are applied, then the system can operate with IBRs and conventional sources, but the fault location accuracy deteriorates due to non-homogeneous source impedance characteristics
Solution Approach 1:
The patent changes the measurement parameter from traditional impedance-based distance measurement to a fault factor based on the angle relationship between voltage and current. This parameter transformation makes the measurement insensitive to source impedance characteristics, enabling accurate fault location whether the source is IBR or conventional generator, as the fault factor depends only on local measurements and the fundamental fault physics.
3Ease of operation
If local measurement-based protection is used, then the system can operate independently without communication, but the measurement precision deteriorates due to mutual coupling effects between circuits
Solution Approach 1:
The patent extracts the essential fault information from local measurements by introducing a fault factor that isolates the fault contribution from each circuit. By taking out only the relevant information (the angle relationship between voltage and current) and ignoring the mutual coupling effects, the method achieves accurate fault detection using only local measurements, maintaining independence while ensuring precision.
Data Source
Figure 1A~2
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Figure 5A~5B
AI summary
The present disclosure relates to a method for determining a fault in a double-circuit line comprising a first line and a second line. The method comprises calculating a first angle of a power at a beginning of a monitored line length of the first line, calculating a second angle of a power at an end of the monitored line length of the first line, performing an operation with the first angle and the second angle to calculate a first fault factor, and determining whether the fault is on the first or second line based on a polarity of the first fault factor. The disclosure further relates to a corresponding device and system.