DFT Phasor Frequency Estimation for Rapid Power System Changes
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Solution Overview
Problem
Existing methods for determining the frequency and phasor measurements in electrical power systems face challenges in accuracy and reliability, particularly during rapid frequency changes due to faults and load variations, which can lead to system instability and malfunctions.
Innovation Solution
A method and device for estimating frequency and phasors using discrete Fourier transform (DFT) phasors, involving interpolation and correction functions based on analytical expressions, to improve accuracy and reliability of frequency determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DFT methods are used for frequency determination, then the method is simple and computationally efficient, but the accuracy deteriorates during rapid frequency changes and system contingencies
Solution Approach 1:
The patent applies preliminary action by estimating a second DFT phasor at a first time interval before the first time (using approximated frequency) before the actual measurement is taken. This predictive approach allows the system to prepare corrected phasor values in advance, improving frequency determination accuracy during rapid changes while maintaining computational efficiency through structured preprocessing.
Solution Approach 2:
The patent implements feedback by using the determined frequency to correct subsequent DFT phasor estimates. The process continuously refines frequency determination by comparing actual phasor measurements with estimated phasors, using the frequency information to adjust and improve future estimates, thereby maintaining high accuracy during dynamic conditions.
2Productivity
If DFT phasors are used during rapid frequency changes, then computational speed is maintained, but measurement accuracy deteriorates due to frequency deviations from nominal
Solution Approach 1:
The patent applies parameter changes by adjusting the time interval for phasor estimation based on the approximated frequency. When frequency deviations occur, the system dynamically modifies the estimation parameters (time intervals and interpolation factors) to compensate for the deviations, maintaining both computational speed and measurement accuracy during rapid frequency changes.
3Reliability
If frequency stability is maintained in the power system, then system reliability is improved, but the system becomes less adaptable to rapid load variations and renewable energy fluctuations
Solution Approach 1:
The patent implements dynamics by creating a frequency determination system that adapts its behavior based on current system conditions. The method dynamically adjusts estimation parameters and uses real-time frequency information to modify subsequent measurements, allowing the system to maintain reliability during normal operation while quickly adapting to rapid frequency changes during contingencies or load variations.
Data Source
AI summary
A method for providing a frequency of an electrical quantity in an electrical power system comprises obtaining, with respect to a first time, a first discrete Fourier transform (DFT) phasor of an electrical quantity in the electrical power system, estimating a second DFT phasor at a time interval before the first time, where the time interval depends on an approximated frequency, and determining the frequency at the first time based on the first and the second DFT phasor.