Transformer Tap Changer Control for Multi-Phase Voltage Balance
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Solution Overview
Problem
Multi-phase power systems face challenges in efficiently regulating voltage, particularly when imbalanced loads occur, due to inadequate or inefficient operation of tap changers, leading to exacerbated load imbalances.
Innovation Solution
The implementation of a power system with regulated transformers and a method for voltage regulation that accounts for phase-to-phase and phase-to-neutral voltages, along with phase angle balancing, using a controller to manage tap changers and instrument transformers to adjust voltage levels in both forward and reverse power flow directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tap changers are used for voltage regulation in multi-phase power systems, then voltage levels can be adjusted, but load imbalances are exacerbated when tap changers are not moved efficiently
Solution Approach 1:
The controller receives real-time measurements of phase-to-phase and phase-to-neutral voltages, along with phase angle information, and uses this feedback to automatically adjust tap changer positions. This closed-loop control ensures voltage regulation stability while maintaining load balance by continuously adapting to system conditions.
Solution Approach 2:
The tap changers are controlled dynamically based on real-time system conditions rather than fixed positions. The controller adjusts tap positions adaptively by considering phase angle differences and voltage imbalances, allowing the system to respond to changing load conditions and maintain optimal performance.
2Adaptability or versatility
If individual tap changers are used for each phase, then local operational control is achieved, but device complexity increases
Solution Approach 1:
The control functions for multiple tap changers are merged into a single centralized controller that manages all phases. This unified control approach reduces overall system complexity by eliminating the need for separate control devices for each phase while maintaining the ability to independently adjust each tap changer based on system needs.
Solution Approach 2:
The single controller performs multiple functions: it monitors all phase voltages, calculates phase angle differences, determines optimal tap positions, and controls multiple tap changers. This multi-functional approach reduces the number of discrete devices needed while providing comprehensive phase-specific control capability.
3Measurement precision
If tap changers are adjusted frequently to maintain voltage levels, then voltage regulation precision is improved, but operational efficiency decreases due to excessive movements
Solution Approach 1:
The controller adjusts tap changers only when and by the amount necessary to maintain voltage within acceptable ranges, rather than making frequent small adjustments. By calculating optimal tap positions based on phase angle and voltage measurements, the system makes precise partial adjustments that achieve voltage regulation with minimal movements, improving operational efficiency.
Solution Approach 2:
The controller predicts the required tap position adjustments by analyzing current voltage and phase angle conditions, making proactive adjustments before voltage deviations become problematic. This preliminary action prevents excessive corrections and maintains voltage stability with fewer tap changer movements.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A power system can include a first tap changer for a first regulated transformer, where the first tap changer has a plurality of first positions. The power system can also include a second tap changer for a second regulated transformer, where the second tap changer has a plurality of second positions. The power system can further include at least one first instrument transformer coupled to the first regulated transformer. The power system can also include at least one second instrument transformer coupled to the second regulated transformer. The power system can further include a controller coupled to the at least one first instrument transformer and the at least one second instrument transformer, where the controller adjusts the first tap changer to a first adjusted position among the first positions based on the first measurements of the first regulated transformer and the second measurements of the second regulated transformer.