Current Transformer Secondary Open-Circuit Fault Detection
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Solution Overview
Problem
Conventional methods for detecting faults in the secondary circuit of current transformers are unreliable, leading to erroneous activation of protective functions in high-voltage networks, which can disrupt power supply.
Innovation Solution
A method and device for detecting faults in the secondary circuit of a current transformer by analyzing current values and determining a selection time interval based on current change magnitude and threshold, using a current transformer with a primary conductor formed by a high-voltage conductor, to reliably identify open circuits and prevent false protective function activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fault detection methods are used in current transformer secondary circuits, then the system structure remains simple, but the reliability of fault detection deteriorates leading to erroneous protective function activation
Solution Approach 1:
The fault detection method segments the detection process into distinct phases: initial current value acquisition, selection time interval determination based on current change quantity, and fault inference based on average current comparison. This segmentation allows each phase to be optimized independently, improving overall detection reliability without requiring a completely complex system architecture.
Solution Approach 2:
The method performs preliminary actions by determining the selection time interval before conducting the fault detection comparison. The current change quantity is calculated in advance, and based on this, an appropriate time interval is selected to ensure that the detection is performed at the optimal moment, thereby improving reliability without adding continuous complex monitoring.
2Measurement precision
If the selection time interval is determined based on current change quantity and threshold, then the fault detection precision is improved, but the computational complexity increases
Solution Approach 1:
The selection time interval is made dynamic rather than fixed. It is determined based on the current change quantity, which varies with different fault conditions and operating states. This dynamic adaptation allows the detection precision to be optimized for each specific situation without requiring an overly complex predetermined system.
Solution Approach 2:
The method changes the parameter of time interval based on the current change quantity. By adjusting the time interval parameter according to the measured current change, the system achieves higher detection precision. The threshold-based determination keeps the computation relatively simple while still achieving adaptive precision.
3Reliability
If fault detection is performed continuously, then the reliability improves, but the energy consumption and processing load increase
Solution Approach 1:
Instead of continuous monitoring, the method employs periodic action by performing fault detection at specific intervals determined by the selection time interval. The detection is triggered based on current change events rather than running continuously, reducing energy consumption while maintaining reliability through strategically timed measurements.
Solution Approach 2:
The method skips unnecessary continuous monitoring by rushing through the detection process at critical moments. When a current change exceeds the threshold, the system quickly performs the fault inference calculation and completes the detection cycle, rather than maintaining constant monitoring. This reduces energy usage while still catching faults when they occur.
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
Enhances the reliability of fault detection in current transformers, preventing unnecessary circuit breaker trips and ensuring stable power supply by accurately distinguishing between actual faults and normal network conditions.
Implementation Method 1
current transformers are conventionally used for current measurement. These current transformers can transmit measurement signals to downstream systems
Data Source
Figure 1~2
Figure 3
AI summary
Described is a method for detecting a fault, in particular an open circuit, in a secondary circuit (6) of a current transformer (3), the primary conductor (4) of which is formed by a part of a high-voltage conductor (2), wherein the method comprises: inferring a fault in the secondary circuit (6) if an magnitude of the mean current (20) at a time point in time within a selection time interval (ΔtA) is less than a current threshold (21), wherein the selection time interval (ΔtA) is determined based on a current change quantity (22) and a current change threshold (23), wherein the current change quantity (22) is formed based on at least two current values (13) of an electric current (I_P) flowing in the secondary circuit (6) assigned to different time points.