Fault Distance Calculation Without Y0 and q Parameters
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Solution Overview
Problem
Existing methods for determining the distance to a phase-to-earth fault on a three-phase electric line in compensated networks require accurate setting parameters like zero-sequence admittance (Y0) and distribution factor (q), which are often inaccurate, leading to errors in fault distance estimation, especially at low-ohmic fault resistance values.
Innovation Solution
A method using four equations derived from an equivalent circuit for a phase-to-earth fault on a three-phase electric line, which estimates fault distance without relying on parameters Y0 and q, thereby eliminating the need for their precise determination and approximation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If setting parameters Y0 and q are used in fault distance calculation, then the calculation can be performed, but the accuracy deteriorates due to inaccuracies in these parameters
Solution Approach 1:
The patent extracts and eliminates the problematic setting parameters Y0 and q from the fault distance calculation. By reformulating the calculation method to not depend on these parameters, the invention removes the source of accuracy deterioration while maintaining the ability to perform fault distance estimation.
Solution Approach 2:
The invention changes the parameters used in the fault distance calculation from the traditional Y0 and q to a new set of parameters that can be accurately determined from measurements. This parameter substitution resolves the accuracy issue by using more reliable parameters.
2Productivity
If approximate values for Y0 and q are used, then the calculation can proceed, but the fault distance estimation accuracy deteriorates especially at low-ohmic fault resistance
Solution Approach 1:
The patent removes the dependency on approximate parameters Y0 and q from the calculation system. By extracting these problematic parameters from the calculation framework, the invention eliminates the trade-off between calculation capability and accuracy, allowing both to be maintained at high levels.
3Reliability
If dedicated equipment is used to measure and update Y0, then parameter accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent enables the system to determine accurate fault distance without requiring external dedicated measurement equipment for Y0. The method uses readily available measurements from the power system itself, allowing the system to serve its own measurement needs without additional complexity.
Solution Approach 2:
The invention makes the fault location system universal by eliminating the need for specialized measurement equipment. The same measurement infrastructure used for normal operation is leveraged for fault distance determination, removing the need for separate dedicated equipment.
Data Source
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AI summary
Method and apparatus for determining a distance to a phase-to-earth fault on a three-phase electric line of an electric network, the apparatus comprising means for determining, during a phase-to-earth fault (F) on the three-phase electric line (30), current and voltage values, when a neutral to earth admittance of the electric network outside the electric line (30) has a first value, means for determining current and voltage values, when the neutral to earth admittance of the electric network outside the electric line (30) has a second value different from the first value, and means for determining the distance to the phase-to-earth fault (F) from the measuring point (40) on the basis of the determined current and voltage values, wherein the means for determining the distance are configured to use four equations derivable from an equivalent circuit for a phase-to-earth fault on a three-phase electric line.