Power Line Fault Detection Using Phase Angles During Power Swings
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Solution Overview
Problem
Existing power system fault detection methods during power swings are slow, leading to delayed fault identification and increased risk of major power outages or blackouts, as they struggle to differentiate between faults and power swings, resulting in unstable and unsafe system operations.
Innovation Solution
A method that estimates voltages at a second position of a power line based on measured electrical quantities at a first position, determining phase angles between the two positions to rapidly detect faults during power swings by analyzing phase angle changes and their durations or rates, thereby reducing the time to trip and improve system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fault detection methods are used during power swings, then relay operations are prevented from mistrip, but fault detection speed is slow leading to delayed fault identification
Solution Approach 1:
The system performs preliminary estimation of voltages at the second position based on measured electrical quantities at the first position before fault detection is needed. This preliminary calculation of phase angles between voltages at different positions enables rapid fault identification when disturbances occur, eliminating the need for slow conventional analysis during actual events.
Solution Approach 2:
The patent replaces conventional mechanical/electrical measurement methods with a computational approach using phase angle analysis. By calculating phase angles between estimated and measured voltages, the system achieves fast digital processing of fault conditions without relying on slower physical measurement and comparison methods.
2Stability of the object's composition
If power-swing blocking function is activated to prevent undesired relay operations, then system stability is maintained during power swings, but fault removal is delayed when faults occur during swings
Solution Approach 1:
The patent introduces phase angle difference as an intermediary parameter to distinguish between power swings and faults. By analyzing the phase angle relationship between voltages at different positions, the system can identify faults during swings without activating blocking, enabling fast fault removal while maintaining stability during normal swings.
Solution Approach 2:
The system changes the monitoring parameter from conventional impedance-based methods to phase angle-based analysis. This parameter change enables the detection of faults during power swings by identifying abnormal phase angle relationships, allowing the relay to operate correctly during swings while blocking during normal swing conditions.
3Ease of operation
If conventional voltage measurement methods are used at a single position, then measurement simplicity is maintained, but fault detection precision during power swings is insufficient
Solution Approach 1:
The patent segments the voltage measurement analysis by comparing voltages at two different positions (first and second positions) on the power line. By dividing the measurement task into multiple spatial points and analyzing phase angle relationships between them, the system achieves superior fault detection precision while maintaining operational simplicity through automated calculation.
Data Source
AI summary
Embodiments of present disclosure provides methods for determining a fault of a power system. Methods include estimating, based on measured electrical quantities at a first position of a power line in the power system, voltages at a second position of the power line, the measured electrical quantities being associated with three phases of the power system and comprising voltages at the first position of the power line. The methods include determining at least one phase angle between the voltages at the first position and the estimated voltages at the second position, and detecting the fault based on the at least one phase angle during a power swing. In a method according to the present disclosure, a three-phase fault during a power swing is identified in a shorter time, and thus the tripping is performed with a faster speed.