OLTC Transformer Voltage Regulation via Adaptive Set-Point Control
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Solution Overview
Problem
On-load tap changers in electric power systems experience frequent voltage adjustments due to variable distributed generation, leading to increased wear and reduced service life, as well as instability in voltage regulation, particularly during reverse power flow conditions.
Innovation Solution
Implementing a control scheme with a hysteresis factor that dynamically adjusts voltage set-points based on previous tap changes, reducing the frequency of tap changes and maintaining stable voltage control by allowing limited power flow variations without additional short-term adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If on-load tap changers frequently adjust voltage to maintain quality, then voltage regulation quality is improved, but wear on tap changer mechanisms increases and service life decreases
Solution Approach 1:
The control scheme dynamically adjusts the voltage set-point based on real-time power flow conditions. When power flow reverses, the system automatically switches between different set-points (first set-point for forward flow, second set-point for reverse flow), allowing the voltage reference to adapt to changing operational modes without requiring frequent tap changes
Solution Approach 2:
The system changes the voltage set-point parameter based on power flow direction. By detecting reverse power flow conditions, the controller switches between different voltage set-points, which accommodates voltage variations caused by distributed generation without triggering unnecessary tap changes, thereby reducing mechanical wear
2Stability of the object's composition
If on-load tap changers respond to voltage variations from distributed generation, then voltage stability is improved, but the frequency of tap changes increases causing excessive wear
Solution Approach 1:
The control scheme incorporates feedback by continuously monitoring power flow direction through the transformer. This feedback mechanism allows the system to detect reverse power flow conditions and adjust the voltage set-point accordingly, maintaining voltage stability without responding excessively to every voltage fluctuation that would trigger unnecessary tap changes
Solution Approach 2:
The system dynamically switches between different voltage set-points based on operational conditions. This dynamic adaptation allows the controller to maintain voltage stability during reverse power flow without requiring frequent tap adjustments, as the set-point itself adapts to the changing system state
3Device complexity
If voltage set-point is kept constant to simplify control, then control complexity is reduced, but voltage regulation accuracy deteriorates under reverse power flow conditions
Solution Approach 1:
The control scheme transitions from a static constant set-point approach to a dynamic conditional set-point approach. The system maintains simplicity by using only two discrete set-points rather than complex continuous control, while improving accuracy by selecting the appropriate set-point based on power flow direction detection
4Measurement precision
If multiple voltage set-points are used to accommodate reverse power flow, then voltage regulation accuracy is improved, but control complexity increases
Solution Approach 1:
The system uses a dynamic switching mechanism between two voltage set-points based on power flow direction. This approach improves voltage regulation accuracy under reverse power flow conditions while maintaining relatively simple control logic through clear conditional branching rather than complex multi-parameter control algorithms
Data Source
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AI summary
An electric power system (500) includes an on-load tap changing (OLTC) transformer (550). The transformer includes a plurality of primary windings (554) and a plurality of secondary windings (556). At least a portion of one of the primary windings and the secondary windings are inductively coupled to each other. The system also includes at least one on-load tap changer (600) coupled to at least one of the primary windings and the secondary windings. The on-load tap changer is selectively configurable to regulate the portion of at least one of the primary windings and the secondary windings inductively coupled to each other. The system further includes at least one processor (115) coupled to the on-load tap changer. The processor is configured to adaptively regulate a voltage set-point of the on-load tap changer as a function of an adaptive OLTC transformer power flow dependent voltage set-point characteristic.