Fault Location Algorithm for Phase-to-Earth Faults
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing impedance-based fault localization algorithms struggle to accurately locate single-phase earth faults in high impedance earthed networks due to factors like fault resistance and load variations, and are often inaccurate in systems with non-homogeneous lines and unbalanced loading.
Innovation Solution
A method that determines two possible fault location alternatives using fault loop models, one assuming the load is between the measuring point and the fault, and another assuming the fault is between the measuring point and the load, with optimal selection of voltage and current quantities for improved localization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If impedance based fault location algorithms are used, then implementation is simple and utilizes existing signals, but accuracy deteriorates in high impedance earthed networks due to fault resistance and load effects
Solution Approach 1:
The invention segments the fault location problem into two distinct scenarios: (1) fault before load, and (2) fault after load. By creating separate calculation models for each scenario, the algorithm can selectively apply the appropriate model based on system conditions, thereby improving accuracy in high impedance networks while maintaining implementation simplicity through modular structure.
Solution Approach 2:
The invention changes the mathematical parameters and equations used in fault location calculations based on the identified fault scenario. Different impedance relationships and calculation formulas are applied depending on whether the fault occurs before or after the load, allowing the system to adapt to varying network conditions and maintain accuracy across different earthed network types.
2Device complexity
If prior art algorithms assume load is at the end point of the line, then calculation is simplified, but accuracy deteriorates when loads are distributed or located at the beginning of the feeder
Solution Approach 1:
The invention makes the fault location algorithm dynamic by providing two alternative calculation models that can be selected based on the actual system configuration. Rather than using a fixed assumption about load location, the system can dynamically choose the appropriate model (fault before load or fault after load) to match the actual physical arrangement, thereby maintaining accuracy without excessive complexity.
3Reliability
If delta quantities are used to eliminate load current and systematic errors, then measurement robustness is improved, but steady-state zero-sequence and negative-sequence quantities remain as error sources in unbalanced systems
Solution Approach 1:
The invention extracts and separately handles the steady-state sequence components (zero-sequence and negative-sequence) that cause errors in unbalanced systems. By identifying and accounting for these components in the fault location calculation, the algorithm removes their harmful effects while maintaining the benefits of using delta quantities for eliminating load current and systematic measurement errors.
Data Source
Figure 1~4
Figure 2
Figure 3
AI summary
A method, system and apparatus for determining a distance of a phase-to-earth fault on a three-phase electric line (30), the apparatus (40) being configured to determine a first estimate value for a distance between the measuring point (40) and a point of fault (F) on the basis of a first equation based on a fault loop model of the electric line, in which model the load of the electric line is located between the measuring point and the point of fault; determine a second estimate value for the distance on the basis of a second equation based on a fault loop model of the electric line, in which model the point of fault is located between the measuring point and load of the electric line; and select, according to predetermined criteria, one of the determined two estimate values as the distance between the measuring point and the point of fault.