Oscillation Detection Device for Power Swing Identification
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Solution Overview
Problem
Existing electrical power supply network protection systems often mistakenly identify power swings as impermissible operating states, leading to unnecessary shutdowns and potential blackouts, due to the inability to reliably distinguish between power swings and faults based on impedance values.
Innovation Solution
A method for generating a pendulum signal by analyzing the characteristics of impedance values, including constant distance from the center, constant angular velocity, and constant angular acceleration, to reliably detect power swings and prevent false tripping signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If swing detection device is added to prevent false tripping, then false tripping is reduced, but device complexity increases
Solution Approach 1:
The swing detection device is designed with multi-functionality: it can detect both synchronous power swings (partial impedance trajectory) and asynchronous power swings (full impedance trajectory) using the same detection principles. The device analyzes characteristic properties (circular/elliptical curve patterns, constant distance from center, constant angular velocity) to generate swing signals that block false tripping, thereby reducing false tripping rates without significantly increasing device complexity
Solution Approach 2:
The swing detection device monitors changes in impedance parameters (magnitude and phase angle) over time. By detecting constant distance from the center of the impedance curve and constant angular velocity, the system identifies power swing conditions and generates appropriate blocking signals, achieving high reliability with relatively simple parameter-based detection logic
2Measurement precision
If multiple swing detection criteria are used, then detection accuracy is improved, but computational complexity increases
Solution Approach 1:
The swing detection device implements a hierarchical detection approach: it first checks for basic circular/elliptical curve patterns in the impedance trajectory, then verifies constant distance from the center, and finally confirms constant angular velocity. This partial action approach achieves high detection accuracy by applying multiple criteria only when necessary, avoiding unnecessary computational complexity for simple cases
Data Source
AI summary
The invention relates to a method for production of an oscillation signal which indicates oscillation in an electrical power supply system, in which measured values which characterize current and voltage at a measurement point in the electrical power supply system are detected and are converted to digital current and voltage vector measured values, and impedance values on the complex numerical plane are calculated from the current vector measured values and the voltage vector measured values. A curve profile formed by the impedance values is considered and, if appropriate, the oscillation signal is produced using characteristic properties of the curve profile. In order to specify a method such as this, by means of which an oscillation can be identified as reliably as possible, it is proposed that a first oscillation supposition signal is produced when the separation of the impedance values from an oscillation centre point remains essentially the same and a second oscillation supposition signal is produced when the rate at which the impedance values approach the curve profile remains essentially the same. The oscillation signal is produced when both the first and the second oscillation supposition signal are present. The invention also relates to a protective device or measurement instrument having a corresponding oscillation identification device.