Fault Location Accuracy via Signal Correlation Analysis
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Solution Overview
Problem
Existing fault location methods in electrical power supply networks face inaccuracies due to incorrect data window positioning, especially when using traveling wave principles, which can lead to delayed identification of fault occurrences and incorrect fault location.
Innovation Solution
A method that compares estimated current and voltage values at one line end with measured values at the other end to determine the start of a data window, allowing for precise positioning based on discrepancies, thereby improving the accuracy of fault location by using high sampling rates and mathematical models to account for line parameters and characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the data window start is established based on protective function excitation signals, then the fault location method is simple to implement, but the data window positioning becomes inaccurate leading to delayed fault identification
Solution Approach 1:
The patent introduces an intermediary mechanism (signal correlation analysis) between the protective function excitation and the data window positioning. By comparing the measured signal at one line end with the estimated signal propagated from the other line end, the system identifies the precise fault occurrence time without directly relying on protective function triggers, thus achieving accurate data window positioning while maintaining implementation feasibility
Solution Approach 2:
The patent replaces the mechanical/time-based triggering system (protective function excitation signals) with a signal processing-based system (correlation analysis of measured and estimated signals). This substitution allows for more precise timing identification by analyzing signal characteristics rather than relying on threshold-based protective relays, improving data window positioning accuracy
2Ease of manufacture
If the data window start is established based on protective function excitation signals, then the implementation remains simple, but the fault location time is delayed
Solution Approach 1:
The patent performs preliminary signal processing and correlation analysis continuously or in advance, so that when a fault occurs, the data window can be immediately positioned accurately without waiting for protective function excitation. By preparing the signal comparison mechanism in advance and using the correlation between measured and estimated signals to identify fault occurrence time, the system reduces fault identification delay while maintaining ease of implementation
Solution Approach 2:
The patent substitutes the time-consuming protective function triggering mechanism with a faster signal correlation-based timing identification method. By analyzing the correlation between measured and estimated signals directly, the system can identify fault occurrence time more rapidly, reducing the loss of time while keeping the overall implementation simple
3Device complexity
If single-ended fault location methods are used, then the outlay is low, but the measurement accuracy of current and voltage transformers significantly affects fault location accuracy
Solution Approach 1:
The patent uses signal propagation models as an intermediary to connect measurements from one line end with the fault location determination. By estimating what the signal should look like at the measured line end based on measurements from the other line end, the system can identify faults more accurately without requiring direct simultaneous measurements from both ends, thus maintaining low outlay while improving accuracy
Solution Approach 2:
The patent changes the approach from directly using measured current and voltage values (which are subject to transformer accuracy limitations) to using signal propagation characteristics and correlation analysis. By transforming the problem into comparing signal waveforms and their temporal relationships rather than direct impedance calculations, the system reduces sensitivity to measurement transformer accuracy while keeping equipment requirements simple
4Measurement precision
If two-ended fault location methods are used, then the fault location accuracy improves, but the complexity of combining measurement values from both line ends increases
Solution Approach 1:
The patent uses signal propagation models and correlation analysis as intermediaries to simplify the combination of measurement values from both line ends. Instead of directly combining complex measurement data requiring synchronization and coordinate transformation, the system compares the temporal and waveform characteristics of measured signals with estimated signals, reducing the complexity of data integration while maintaining high fault location accuracy
Solution Approach 2:
The patent replaces the complex mechanical/synchronization-based data combination process with a signal processing approach. By using correlation analysis and waveform comparison in the time or frequency domain, the system can integrate information from both line ends more simply, reducing computational and synchronization complexity while preserving measurement precision
Data Source
AI summary
A method determines a fault position of a fault on an electrical line. First time stamped current and voltage values are measured at a first line end. Second time stamped current and voltage values are measured at a second line end. The fault position of the line is determined from these measured values. To carry out positioning of a data window for fault location according to the traveling wave principle, after the first current and voltage values are measured at the first line end, the second current and voltage values are determined, which indicate the current or voltage at the second line end. Estimated second current or voltage values are compared with the values measured at the second line end, and the first and second current and voltage values that lie within a period of time established by a first data window are employed to determine a first fault position.