Multiphase Power Network Fault Identification Using Sequence Impedance Matrices
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Solution Overview
Problem
Conventional fault location methods for three-phase electrical power circuits are limited in identifying faults in multiphase power networks, particularly in single-phase or double-phase laterals, due to the complexity of multiphase topology, leading to difficulties in accurately locating faults in these segments.
Innovation Solution
The method involves using intelligent electronic devices (IEDs) to measure current during faults, calculating equivalent sequence impedances, and building sequence bus impedance matrices to estimate per unit fault distances, identifying potentially faulted segments by analyzing current measurements and impedance coefficients within a specific range, and repeating the process for all segments in the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fault location methods based on sequence domain modeling are used, then the method is simple to implement, but it cannot accurately locate faults in single-phase or double-phase laterals of multiphase power networks
Solution Approach 1:
The power network is divided into multiple segments along the feeder, with each segment representing a potential fault location zone. The algorithm calculates fault distance for each segment independently by comparing measured currents with calculated currents assuming faults at different locations, enabling precise identification of the faulted segment while maintaining compatibility with multiphase topology including single-phase and double-phase laterals.
Solution Approach 2:
The method transforms the fault location problem from a continuous estimation problem into a discrete segment identification problem by changing the parameter representation from continuous fault distance to discrete segment indices. This is achieved by calculating per-unit fault distances for each segment and identifying segments where the calculated fault distance falls within a valid range (0 to 1), thereby improving both accuracy and adaptability to complex multiphase configurations.
2Adaptability or versatility
If the fault location method is extended to cover all segments including single-phase and double-phase laterals, then the coverage is improved, but the complexity of the method increases
Solution Approach 1:
The algorithm is designed with universal applicability to handle multiple phase configurations (single-phase, double-phase, and three-phase laterals) using a unified mathematical framework. The same core algorithm processes all segment types by appropriately configuring the impedance matrices and current measurements for each segment type, eliminating the need for separate specialized algorithms for different phase configurations and thereby managing complexity while maintaining comprehensive coverage.
Solution Approach 2:
The patent introduces an intermediary computational layer that transforms diverse multiphase fault scenarios into a standardized analysis format. By using sequence component transformation and unified impedance matrix formulations, the method mediates between the complexity of multiphase topology and the simplicity of single-phase fault analysis, enabling comprehensive coverage without proportionally increasing algorithmic complexity.
3Reliability
If conventional methods are used, then the implementation is straightforward, but they are limited to three-phase main lines and cannot detect faults in laterals where over 80% of faults occur
Solution Approach 1:
The method extends fault detection from the traditional three-dimensional three-phase space to include additional dimensional representations for single-phase and double-phase laterals. By incorporating sequence component analysis and calculating equivalent impedances for different phase configurations, the algorithm operates in an expanded parameter space that captures the electrical characteristics of all segment types, thereby improving reliability without requiring fundamentally different implementation approaches.
Solution Approach 2:
The patent performs preliminary calculations of sequence impedances and admittances for all segments before actual fault detection occurs. By pre-computing the impedance matrices and storing them for rapid access during fault events, the method prepares the system to handle diverse fault scenarios efficiently, maintaining implementation simplicity while enabling comprehensive detection across all segment types including the previously undetected laterals.
Data Source
AI summary
Systems and methods for identifying faulted segment(s) in a multiphase power network may include receiving a current measurement that was measured during a fault, obtaining a set of equivalent sequence impedances for the segments, building a set of sequence bus impedance matrices, selecting a segment, calculating coefficients for the segment based on the set of equivalent sequence impedances for the segment and the sequence bus impedance matrices, calculating an estimated per unit fault distance for the segment based at least partially on the current measurement and the coefficients, identifying the segment as a potentially faulted segment if the estimated fault distance for the segment is between about zero and about one, and repeating for each of the segments the calculating coefficients, calculating an estimated per unit fault distance, and identifying as a potentially faulted segment if the estimated fault distance for the segment is between about zero and about one.