Dual-Sequence Fault Location During Pole-Open Conditions
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Solution Overview
Problem
Conventional fault location systems are inaccurate during pole-open conditions due to reliance on single sequence network data, especially when pre-fault sequence currents are non-negligible, leading to significant errors in fault distance calculations.
Innovation Solution
The use of dual-sequence network approaches, incorporating both positive and negative sequence networks, to accurately determine fault locations by compensating for voltage differences across open breaker poles, utilizing impedance-based techniques and processing all six voltage and current waveforms from single or both ends of a transmission line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional single sequence network data is used for fault location during pole-open conditions, then the system simplicity is maintained, but the measurement precision deteriorates significantly due to non-negligible pre-fault sequence currents
Solution Approach 1:
The patent segments the fault location calculation into two distinct sequence networks: positive sequence network and negative sequence network. Each network processes specific current components separately, allowing the system to account for pre-fault sequence currents that would otherwise contaminate a single-network calculation. This segmentation enables accurate fault location during pole-open conditions by isolating and compensating for different current components.
Solution Approach 2:
The patent changes the calculation parameters by introducing separate positive and negative sequence current components (I1 and I2) with distinct impedance values (Z1 and Z2). By transforming the single-sequence calculation into a dual-sequence framework, the system can selectively apply different compensation factors for pre-fault currents, thereby maintaining measurement precision under pole-open conditions while managing complexity through structured parameter organization.
2Measurement precision
If dual-sequence network approaches are used to compensate for pre-fault currents, then the measurement precision improves, but the device complexity increases due to processing multiple sequence networks
Solution Approach 1:
The patent implements a universal dual-sequence calculation framework that handles both normal and pole-open conditions through the same mathematical structure. The system uses a unified set of equations that automatically adapt to different operating conditions by detecting the presence of pole-open conditions and applying appropriate sequence network combinations. This multi-functionality reduces the need for separate specialized circuits for different fault conditions.
Solution Approach 2:
The patent introduces sequence network decomposition as an intermediary processing layer between raw current measurements and final fault location calculation. By transforming measured currents into positive and negative sequence components through mathematical transformation, the system creates intermediate representations that simplify the compensation of pre-fault currents. This intermediary step organizes complex information into manageable sequence components that can be processed systematically.
3Measurement precision
If all six voltage and current waveforms are processed from both ends of the transmission line, then the fault location accuracy is maximized, but the loss of time increases due to extensive data processing
Solution Approach 1:
The patent performs preliminary decomposition of voltage and current waveforms into sequence components before the actual fault location calculation. By pre-processing the six waveforms into positive and negative sequence sets, the system prepares organized data structures that can be quickly combined during fault analysis. This preliminary action reduces the computational burden during the critical fault response period, as the sequence transformation is performed once rather than recalculated during the measurement phase.
Data Source
AI summary
The present disclosure illustrates the errors that are encountered when using both single-ended and double-ended normal-mode fault location calculations when a fault occurs in a pole-open condition. The disclosure provides systems and methods for accurately calculating the location of faults that occur during pole-open conditions, including single-ended approaches and double-ended approaches.