Power Measurement Phase Offset Compensation
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Solution Overview
Problem
Existing power meters face challenges in accurately measuring active and reactive powers due to phase offsets caused by current transformers in transmission lines, requiring complex calibration filtering that increases computational complexity.
Innovation Solution
A method and device that directly compute active and reactive powers using uncalibrated current and voltage signals, then calibrate these powers using sine and cosine values of the phase offset, effectively removing the transformer-induced phase offset without complex filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex calibration filtering is used to correct phase offsets, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the phase offset correction from the signal processing domain and moves it to the power calculation domain. Instead of filtering the current and voltage signals before computation, the method computes power directly from the raw signals and then corrects the power values using phase offset compensation factors, thereby removing the complex filtering requirement while maintaining measurement accuracy
Solution Approach 2:
The patent replaces the mechanical signal filtering approach with a mathematical compensation approach. Rather than using physical filters to correct phase offsets in the time domain, the invention uses computational methods in the frequency domain to adjust the power values, substituting complex signal processing with simpler mathematical operations
2Measurement precision
If phase calibration filtering is applied, then measurement precision is improved, but computational complexity increases
Solution Approach 1:
The patent separates the phase offset correction step from the signal filtering process. By extracting the phase offset as a distinct parameter and applying it as a compensation factor after power computation, the method eliminates the need for computationally intensive filtering operations while achieving the same correction goal
Solution Approach 2:
Instead of correcting the input signals before computation (the conventional approach), the patent inverts the sequence by computing power first and then correcting the output. This reversal simplifies the computational process by avoiding iterative filtering algorithms and using direct mathematical compensation
Data Source
AI summary
A device and method for measuring active and reactive powers of an alternating current includes receiving a first signal representing a current and a second signal representing a voltage, in which the current includes a phase offset with respect to the voltage, calculating an active power and reactive power based on the first and second signals, and calibrating the calculated active and reactive powers with respect to the phase offset using first and second constants, in which the first and second constants respectively correspond to a sine value and a cosine value of the phase offset.