On-Load Tap Changer Control for Reactive Power
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Solution Overview
Problem
Current on-load tap changer (OLTC) control methods in power systems require manual adjustment of voltage reference values to regulate reactive power, which is inefficient and not satisfying, especially when grid conditions or generator operating regimes change.
Innovation Solution
An automated on-load tap changer control method that measures voltage and current on the primary or secondary side of a power transformer, processes these measurements to derive prospective reactive power, compares it to a predefined set-point, and initiates tap-changes to align with the set-point, eliminating the need for manual reference value adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual adjustment of voltage reference value is used to regulate reactive power, then the OLTC can control reactive power output, but the system requires continuous manual intervention and is inefficient when grid conditions change
Solution Approach 1:
The system automatically measures voltage and current, calculates reactive power, and controls the OLTC without manual intervention. The control unit continuously monitors grid conditions and self-adjusts the tap position to maintain reactive power within the specified range, eliminating the need for operator intervention.
Solution Approach 2:
The system implements closed-loop feedback by measuring actual voltage and current, calculating reactive power consumption, comparing it with the specified range, and automatically adjusting the OLTC tap position based on the deviation. This feedback mechanism enables continuous optimization of reactive power control.
2Adaptability or versatility
If voltage regulation is used to control reactive power, then reactive power can be adjusted, but the voltage reference value must be manually re-adjusted when grid conditions change
Solution Approach 1:
The control unit continuously monitors grid conditions including voltage and current measurements, and automatically adjusts the voltage reference value and OLTC tap position in response to changing grid conditions. This real-time feedback eliminates the need for manual re-adjustment and enables rapid adaptation to new operating conditions.
Solution Approach 2:
The system dynamically adapts to changing grid conditions by continuously updating the voltage reference value and OLTC control parameters based on real-time measurements. The control strategy transitions from static manual setting to dynamic automatic adjustment, improving adaptability to varying grid states.
3Productivity
If the OLTC is used to adjust reactive power output, then the generator can meet grid requirements, but the voltage on generator terminals may deviate from nominal value
Solution Approach 1:
The system simultaneously monitors both reactive power output and generator terminal voltage, and adjusts the OLTC tap position and voltage reference value to satisfy both requirements. The feedback control ensures that reactive power meets grid specifications while maintaining terminal voltage within acceptable limits.
Solution Approach 2:
The system dynamically changes multiple parameters including voltage reference value, OLTC tap position, and reactive power setpoint to achieve optimal performance. By coordinating adjustments of these parameters, the system balances reactive power output requirements with voltage stability requirements.
Data Source
AI summary
The present invention relates to an on-load tap changer control method for a power transformer in a power system. The power transformer has a primary side for a connection to a first grid in which electric power is generated, and a secondary side for connection to a second grid in which electrical power is consumed, the power transformer being equipped with an on-load tap changer. The method includes measuring the voltage and current at least on the primary side (u1, i1) or on the secondary side (u2 i2) of the power transformer, processing said measured voltages (u1; u2) and currents (i1; i2) in order to derive prospective reactive power at the output of the power transformer after prospective tap-change, comparing prospective reactive power to a predefined set-point, and—initiating tap-change of on-load tap changer if prospective reactive power is closer to said predefined set-point than actual reactive power.