Automatic Voltage Regulator Reference Phase Selection for Imbalanced Grids
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Solution Overview
Problem
Current methods for determining the reference value for automatic voltage regulators in on-load tap changers often select a single phase or average of three phases statically, leading to inadequate voltage regulation, particularly in distribution networks with phase voltage imbalances, resulting in over- or undervoltage issues.
Innovation Solution
A dynamic method that selects the reference value based on real-time voltage measurements across all three phases, adjusting the phase selection to ensure optimal voltage setpoint adherence and minimize tap changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single phase is selected statically for voltage measurement, then the measurement system is simple, but voltage regulation precision deteriorates due to phase voltage imbalances in distribution networks
Solution Approach 1:
The patent implements dynamic phase selection where the reference phase is not fixed but changes based on real-time voltage conditions. The system evaluates voltage deviations across all three phases and dynamically selects which phase to use as reference, allowing the measurement system to adapt to changing network conditions and maintain precision without excessive complexity
Solution Approach 2:
The system changes the parameter being measured by selecting different phases as reference based on current voltage conditions. Instead of always measuring one fixed phase, the system switches between phases (R, S, or T) depending on which provides the most accurate representation of the actual voltage deviation from setpoint, thereby improving measurement precision
2Reliability
If the average of three phases is used as reference value, then phase imbalance is accounted for, but unnecessary tap changes increase due to reduced measurement precision
Solution Approach 1:
The patent applies local quality by selecting the most representative phase as reference based on local voltage conditions. Instead of uniformly averaging all three phases, the system identifies which phase locally best represents the actual voltage deviation and uses only that phase's measurement, thereby maintaining reliability while avoiding the precision loss that causes unnecessary tap changes
Solution Approach 2:
The system uses feedback by continuously monitoring voltage deviations and using this information to dynamically select the reference phase. The feedback loop evaluates actual voltage conditions and adjusts the reference selection accordingly, preventing the measurement errors that would otherwise trigger unnecessary tap changer operations
3Device complexity
If a fixed phase is used as reference, then the control system is simple to implement, but over- or undervoltage events occur due to phase voltage imbalances
Solution Approach 1:
The control system implements dynamics by transitioning from a static reference phase selection to a dynamic one. The system continuously evaluates voltage conditions and adapts the reference phase selection in real-time, enabling the simple control structure to maintain reliability under varying phase imbalance conditions without becoming complex
Data Source
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AI summary
Dynamic determination method of the reference value of an automatic voltage regulator or controller The method of the invention dynamically determines the reference value (Vref) of an automatic voltage regulator or controller comprising the following steps: - Calculating and/or loading (2) at least one parameter that can determine the potential real deviation of the reference value (Vref) with respect to the optimal voltage setpoint (Vset), - Calculating (3) the value (C) that determines the potential deviation from the reference value (Vref), - Determinating (4) the maximum voltage (Vsup) and minimum voltage (Vinf) levels, - A first verification step (5) of whether Vinf < Vset < Vsup, - A second verification step (6) of whether Vset ≥ Vsup, - A third verification step (7) of whether Vset < Vinf, and - Dynamically selecting (1, 1', 1") at least one phase (R, S, T) for measurement and/or calculation of at least one reference value (Vref).