Protection Function Sensitivity Supervision via Statistical Threshold Adjustment
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Solution Overview
Problem
Existing protection functions in electrical power systems are prone to false actions due to improper threshold settings, leading to unnecessary disturbances and high sensitivity, which can result in damage and increased costs, with current methods being time- and cost-consuming and lacking clear indicators for when false actions will occur.
Innovation Solution
A method that calculates the mean and deviation of test values to determine the probability of false actions, indicating when sensitivity is too high or low, and allows for automatic adjustment of the threshold value to optimize sensitivity, thereby reducing false actions and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the protection function is designed for high dependability with a low threshold value, then the reliability of protection is improved, but the sensitivity becomes too high causing false actions and unnecessary disturbances
Solution Approach 1:
The system performs preliminary testing of the protection function under normal operating conditions before actual operation. By calculating mean values and deviations from multiple test values obtained during normal operation, the system establishes a baseline statistical profile that predicts when the protection function might trigger falsely, allowing threshold optimization before deployment
Solution Approach 2:
The system changes the threshold parameter based on statistical analysis of test values. By calculating the mean and deviation of test values during normal operation, the system determines an optimal threshold that accounts for normal variations in measured values, thereby reducing false actions while maintaining protection reliability
2Ease of operation
If traditional testing methods are used to set threshold values, then the protection function can be configured, but the process is time-consuming and costly with no clear indication of when false actions will occur
Solution Approach 1:
The system performs self-testing and self-evaluation during normal operation. By automatically collecting test values, calculating statistical parameters (mean and deviation), and determining the probability of false actions, the system eliminates the need for extensive manual testing and threshold adjustment by commissioning engineers, significantly reducing commissioning time and cost
Solution Approach 2:
The system provides feedback about the probability of false actions based on statistical analysis of test values. This feedback mechanism allows users to understand under what circumstances false actions are likely to occur, enabling informed decisions about threshold settings and protection function configuration
Data Source
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AI summary
The present invention relates to a method and a device for supervising the sensitivity of a protection function in an electrical power system comprising a metering device for measuring values of a feature, said protection function being configured to initialize an action based on a test value and a threshold value for the feature, wherein said test value is either a measured value or derived from the said measured values, the device (9) comprising a computing unit (3) configured to receive the test values and, repeatedly during the operation of the protection function, to calculate a mean value and a deviation of the test values, to determine the probability of a false action based on the calculated mean value, the threshold value and the calculated deviation, and to indicate that the sensitivity is too high when the probability of a false action exceeds a first limit value for the probability of a false action.