Reactive Power Voltage Correction Within Half an AC Cycle
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Solution Overview
Problem
Existing technologies struggle to effectively address the challenges of fast voltage changes in electrical networks, particularly in response to fast-changing loads and imbalances caused by sources like electrical vehicles and photovoltaic systems, leading to voltage instabilities and economic losses due to slow-reacting voltage correction methods.
Innovation Solution
A method and system for fast correction of voltage during a fraction of an AC period, involving accurate estimation of RMS voltage and application of reactive components like capacitors or inductors to stabilize voltage within a half cycle, using methods such as Least-Mean-Square approximation and stack-based estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional voltage correction methods (tap-changers) are used, then voltage correction is achieved, but the correction speed is slow (takes several AC periods)
Solution Approach 1:
The patent replaces traditional mechanical tap-changers with an electronic control system that uses power electronic switches (thyristors or IGBTs) to control reactive power compensation. This substitution enables voltage correction within a fraction of an AC period instead of several periods, achieving fast response to voltage deviations caused by fast-changing loads.
Solution Approach 2:
The system dynamically changes the reactive power parameter by adjusting the firing angle of power electronic switches controlling capacitor banks or reactors. By varying the reactive power injection/absorption in real-time based on detected voltage deviations, the system achieves rapid voltage correction without mechanical movement.
2Loss of time
If fast RMS estimation methods (signal amplitude method) are used, then RMS voltage is estimated quickly, but the accuracy is very low
Solution Approach 1:
The system performs preliminary calibration by measuring the relationship between signal amplitude and RMS voltage during periods when the voltage waveform is known to be sinusoidal with good harmonics quality. This pre-established relationship is stored and later used for rapid RMS estimation during fast-changing conditions, achieving both speed and accuracy.
Solution Approach 2:
The system continuously monitors actual voltage waveforms and compares estimated RMS values with measured values. When discrepancies are detected, the system adjusts the estimation algorithm parameters or switches to alternative estimation methods, ensuring accurate RMS calculation even during transient conditions with harmonic distortion.
3Speed
If fast voltage correction is applied, then voltage correction speed is improved, but voltage instabilities occur and worsen in distribution lines with photovoltaic systems
Solution Approach 1:
The system applies partial reactive power compensation by adjusting the degree of capacitor bank switching or reactor switching based on the severity of voltage deviation. Instead of always applying maximum correction, the system modulates the reactive power injection to achieve just enough correction to bring voltage within acceptable ranges, preventing over-correction and instability.
Solution Approach 2:
The system uses periodic sampling of voltage at strategic points within the AC cycle (e.g., at voltage zero-crossings or peak points) to detect deviations and trigger correction actions. This periodic measurement approach, combined with phased-locked loop synchronization, ensures that corrections are applied at optimal moments in the AC cycle, maintaining stability even during fast transient conditions.
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 highly accurate and stable voltage correction within a half cycle, reducing voltage instabilities and economic losses by integrating reactive components to maintain voltage within nominal ranges.
Implementation Method 1
correcting voltage during less than a half of the AC period by calculating a required value of reactive power needed to be connected to the network and attaching one or more reactive components with the required value of reactive power in parallel to the load
Data Source
AI summary
Systems and methods for fast correction of voltage during less than a half of an AC period are presented herein. The method includes estimating during less than a half of an AC period, the RMS voltage and after recognizing the required value of voltage to be corrected correcting the voltage by calculating a required reactive power to be connected to the load to correct the voltage.