Fault Detection in Transmission Systems Using Rectified Current Comparison
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Solution Overview
Problem
Current fault detection methods in electrical transmission and distribution systems are inefficient due to reliance on high tension current transformers and complex calculations like Fourier Transforms, which can lead to saturation errors and prolonged decision-making processes.
Innovation Solution
A method and apparatus that rectify and invert AC current signals, measure and scale DC current signals, calculate RMS values, and compare differences to generate a trigger signal for fault detection without using high tension current transformers or complex calculations, utilizing a control unit with rectifier and inverter controls to identify monophasic, biphasic, and triphasic faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high tension current transformers are used to measure and regulate current, then fault detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential measurement function from the complex high tension current transformer system. By using simple voltage measurement combined with mathematical calculation (V/I relationship), the patent eliminates the need for expensive current transformers while maintaining fault detection capability. The measurement function is separated from the transformation function.
Solution Approach 2:
The patent creates a virtual copy of the current signal through mathematical calculation rather than physical measurement. By measuring voltage and calculating current using the known impedance relationship, the system produces an accurate representation of the current without requiring physical current transformers.
2Measurement precision
If complex calculations such as Fourier Transforms are used to determine faults, then measurement precision is improved, but processing time increases
Solution Approach 1:
The patent applies partial action by using only the necessary mathematical operations for fault detection rather than comprehensive signal analysis. Instead of performing full Fourier Transforms, the system uses simplified calculations based on voltage measurement and impedance relationships, achieving sufficient precision for fault detection without excessive processing time.
Solution Approach 2:
The patent changes the approach from time-domain complex calculations to a more efficient parameter-based calculation method. By working with voltage parameters and known impedance values, the system calculates current and detects faults using simpler mathematical operations that maintain accuracy while reducing computational burden.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables rapid and accurate fault detection in transmission and distribution systems, reducing the risk of damage and blackouts by avoiding the need for costly high tension current transformers and complex calculations, thereby shortening the decision-making chain.
Implementation Method 1
Rectifying the ac current signal of the auxiliary services triphasic system
Implementation Method 2
Rectifying and inverting the ac current signal of the transmission and distribution system
Data Source
AI summary
The present invention corresponds to a method and an apparatus for detecting faults in transmission and distribution systems. The method is characterized by the steps of: a) Rectifying the ac current signal of the “auxiliary services” triphasic system; b) Rectifying and inverting the ac current signal of the transmission and distribution system; c) Connecting the step b signal to step a signal; d) Measuring the ac current signal obtained in step b; e) Measuring the dc current signal rectified in step a; f) Scaling the value of the current measured in step e by a scale k factor; g) Calculating the rms value of the signal measured in step d; h) Finding the difference between the values obtained in steps f and g; i) Comparing the absolute value of the step h difference with a reference value m; j) If the comparison made in step i is greater than the reference value m, a trigger signal is generated and the tension is maintained between the dc points of step b in about from 0 to 90%, of the operating tension with no fault. The apparatus comprises, a rectifier; an inverter connected to the rectifier; current measuring means at the rectifier and inverter outlets; and a control unit connected with the rectifier, the inverter and the current measuring means that makes the tripping command of the rectifier and the inverter, and compares the dc current measure at the rectifier outlet with the inverter outlet current, sending a tripping signal according to said comparison.