Harmonic Spectral Analyzer Using Dual-Channel Digitally Controlled Oscillator
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Solution Overview
Problem
Current methods for measuring power at fundamental and harmonic frequencies in electrical power systems are inefficient, particularly due to prolonged calculation times and degradation of phase locked loop performance near sampling frequencies, necessitating a solution for real-time computation.
Innovation Solution
A device and method utilizing a dual-channel digitally controlled oscillator to detect fundamental frequencies and generate orthogonal sinusoidal signals for power measurement, incorporating multipliers, low-pass filters, and adders to compute power components like RMS, active, and reactive power, enabling simultaneous measurement at fundamental and harmonic frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase locked loop (PLL) and band-pass filters are used for computing power at fundamental and harmonic frequencies, then power measurement can be performed, but calculation time is prolonged and PLL performance degrades near sampling frequency
Solution Approach 1:
The patent replaces the mechanical PLL system with a digitally controlled oscillator (DCO) that operates in the digital domain. The DCO uses a numerically controlled oscillator approach with integer or fractional frequency control, eliminating the need for analog PLL components and filters. This substitution enables faster computation of power measurements at fundamental and harmonic frequencies without the performance degradation near sampling frequencies that plagues analog PLL systems.
2Adaptability or versatility
If FFT transform is used for measuring power at fundamental and harmonic frequencies, then comprehensive frequency analysis is achieved, but calculation time increases
Solution Approach 1:
The patent extracts only the specific frequency components of interest (fundamental frequency and selected harmonic frequencies) using the DCO tuned to those specific frequencies, rather than performing a complete FFT transform that analyzes all frequency components. This extraction approach maintains the ability to measure power at critical frequencies while significantly reducing calculation time by avoiding unnecessary computation of unrelated frequency components.
Solution Approach 2:
The patent applies partial action by implementing power measurement at the fundamental frequency and selected harmonic frequencies using DCO, rather than performing exhaustive FFT analysis across the entire frequency spectrum. This selective measurement approach provides sufficient information for power quality assessment and harmonic detection while reducing computational burden and processing time compared to complete spectral analysis.
3Adaptability or versatility
If non-linear loads are present in the power system, then harmonic frequencies are created, but power system effectiveness is reduced and delivery equipment may be damaged
Solution Approach 1:
The patent introduces an intermediary measurement and detection system that uses DCO to specifically identify and quantify harmonic frequencies generated by non-linear loads. By providing accurate real-time measurements of harmonic content and power at different frequencies, the system enables power suppliers to detect harmful harmonics, assess their impact on delivery equipment, and implement appropriate mitigation strategies, thus protecting the power system from harmonic damage while maintaining functionality.
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
Enables near real-time measurement of power at fundamental and harmonic frequencies, improving the accuracy and efficiency of electrical power metering and reducing the risk of harmonic damage to delivery equipment.
Implementation Method 1
Current techniques for computing power at a fundamental frequency or harmonic frequencies are mostly based on phase locked loop (PLL) and band-pass filters
Implementation Method 2
a group of low-pass filters for removing high frequency components from the multiplication products
Data Source
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AI summary
In one embodiment, a measuring device may comprise two oscillators. The first oscillator may generate a local reference signal in a frequency detector to detect a fundamental frequency of the AC. The second oscillator may generate two substantially mutually orthogonal sinusoid signals having the selected frequency. The measuring device further may comprise a first group of multipliers that mixes the two sinusoid signals with a current and a voltage data signal of the AC respectively, a group of low-pass filters for removing high frequency components from the multiplication products, a second group of multipliers for mixing the filtered multiplication products respectively, and a plurality of adders each to sum together a pair of multiplication products of the second group of multipliers.