Synchrophasor Measurement Adaptation for Transient Stability
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Solution Overview
Problem
Conventional Phasor Measurement Units (PMUs) in electric power grids have slow responses and low reporting rates, limiting their ability to provide fast dynamic response and accurate measurements during transients, making them unsuitable for transient stability control.
Innovation Solution
The development of a synchrophasor measurement method that uses GPS-synchronized samples to determine signal distortion levels, selecting between an Improved Zero-Crossing (IZC) method and an Enhanced Phase-Lock-Loop (EPLL) method for estimating frequency and phase angle, allowing for higher sampling rates up to 100 kHz and reporting rates of 120 Hz or higher, enabling rapid situational awareness and transient stability control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PMUs use DFT-based measurement algorithms with six line cycle windows, then measurement reliability is improved, but response speed deteriorates
Solution Approach 1:
The patent changes the fundamental measurement parameter from DFT-based frequency estimation to zero-crossing detection, which operates on a different principle entirely. This allows the system to achieve both high reliability through multiple validation checks and high speed by operating on individual cycles rather than requiring six-line cycle windows.
Solution Approach 2:
The patent replaces the conventional DFT mathematical processing mechanism with an enhanced zero-crossing detection mechanism that uses signal polarity changes and time-stamp comparisons. This substitution enables faster computation while maintaining measurement accuracy through sophisticated validation logic.
2Device complexity
If conventional PMUs operate at 10-60 Hz reporting rates, then device complexity is reduced, but dynamic response capability deteriorates
Solution Approach 1:
The patent implements a dynamic reporting rate that adapts to system conditions. The system can operate at higher rates (120 Hz or 1 kHz) when dynamic response is needed, while maintaining lower rates when stability is achieved. This dynamic adjustment allows the system to provide fast dynamic response capability without permanently increasing device complexity.
Solution Approach 2:
The patent changes the reporting rate parameter from fixed (10-60 Hz) to variable (120 Hz or 1 kHz), enabling the system to respond dynamically to changing system conditions. This parameter change allows fast dynamic response while managing device complexity through intelligent sampling rate selection.
3Stability of the object's composition
If conventional PMUs use fixed six line cycle measurement windows, then measurement stability is improved, but adaptability to transient conditions deteriorates
Solution Approach 1:
The patent implements a dynamic measurement window that adapts to transient conditions. During normal operation, the system uses standard measurement intervals for stability. During detected transients (through rate of change thresholds or distortion detection), the system switches to enhanced zero-crossing detection with shorter effective windows, providing adaptability to transient conditions while maintaining measurement stability during normal operation.
Solution Approach 2:
The patent uses feedback from signal distortion detection and rate-of-change monitoring to adjust measurement behavior. When transients are detected through these feedback mechanisms, the system activates the enhanced zero-crossing detection mode, allowing adaptability to transient conditions while maintaining measurement stability through condition-based activation.
4Adaptability or versatility
If conventional PMUs implement IEEE C37.118 standard, then interoperability is improved, but measurement speed deteriorates
Solution Approach 1:
The patent segments the measurement process into distinct operational modes: standard IEEE C37.118 compliance mode for interoperability, and enhanced zero-crossing detection mode for high-speed measurements. This segmentation allows the system to maintain interoperability through standard compliance while achieving high measurement speeds when needed through the alternative detection method.
Data Source
AI summary
A synchrophasor measurement method for a device configured to take synchronized measurements in a power system is provided. The synchrophasor measurement method includes receiving global positioning system (GPS)-synchronized samples of a signal sensed by the device from the power system; determining a level of distortion of the signal; selecting, based on the level of distortion, a computation method, the computation method being one of an improved zero-crossing (IZC) method and an enhanced phase-lock-loop (EPLL) method; performing the selected computation method to determine at least one parameter of the signal at a reporting frequency, which is at least twice a line frequency of the power system; and outputting, at the reporting frequency, the at least one parameter to an operator of the power system to allow the operator to perform at least one of a monitoring and a controlling of at least one element of the power system.