Simultaneous Fault Detection in Unbalanced Distribution Networks
Solution Overview
Problem
Existing fault detection and location methods in power distribution systems are inadequate for simultaneous faults, particularly in unbalanced, mixed-phase networks with distributed generators, as they are limited to single fault detection and require excessive instrumentation and computational resources.
Innovation Solution
A multi-end measurement and impedance-based algorithm for detecting and locating simultaneous faults in unbalanced three-phase distribution networks, using a system with measurement units, processors, and communication networks to analyze phase current mismatches and determine fault locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If impedance-based methods are used for fault detection and location, then measurement requirements are minimized, but the methods cannot detect simultaneous faults in ungrounded networks
Solution Approach 1:
The patent transforms the fault detection problem from the time domain to the frequency domain by applying Fourier transform to current measurements. This parameter transformation enables the detection of simultaneous faults in ungrounded networks by analyzing frequency components of the currents, which contain fault information even when time-domain analysis fails due to low fault currents in ungrounded systems.
Solution Approach 2:
The patent introduces frequency domain analysis as an intermediary method between traditional impedance-based detection and advanced simultaneous fault detection. By using frequency spectrum analysis of current measurements, the system can extract fault information without requiring additional sensors or complex measurements, thus maintaining simplicity while achieving reliable simultaneous fault detection.
2Speed
If travelling wave-based methods are used for fault location, then fault location speed is improved, but the methods become complicated under complex topologies
Solution Approach 1:
The patent extracts only the essential information needed for fault location by analyzing frequency components of current measurements at existing measurement points. Instead of using complex travelling wave analysis that requires processing wave propagation information throughout the network, the method extracts fault location information directly from local current frequency spectra, significantly reducing computational complexity while maintaining fast fault location capability.
3Measurement precision
If additional devices are deployed for fault detection in ungrounded networks, then fault detection precision is improved, but system cost and complexity increase
Solution Approach 1:
The patent makes existing current measurement devices perform multiple functions: they simultaneously provide data for normal operation monitoring, single fault detection, and simultaneous fault detection through frequency domain analysis. By processing the same current measurements differently in the frequency domain, the system achieves precise simultaneous fault detection without requiring additional sensors or measurement devices, thus avoiding increased system complexity and cost.
Data Source
AI summary
Systems and methods are configured for detecting and locating simultaneous faults in a distribution network having primary and secondary buses connected with two-terminal sections. The measured three-phase voltages and currents from the primary buses are received via a communication network, and the series impedances and shunt admittances and the pre-fault connectivity topology are retrieved from the storage. Simultaneous faults are determined to occur by verifying at least one phase of at least three buses having phase current mismatches determined as the differences between the measured values and calculated values using normal topology and phase voltages that are greater than a threshold. A location for each fault is determined individually if the faults are occurring at non-adjacent sections in the distribution network, or jointly if the faults are occurring at adjacent sections in the distribution network. Faulted line sections are isolated by activating switching operations for connected switches to the faulted line sections that communicatively linked to distribution system grid via communication network.