UPS Power Curve Control for Transformer Saturation Prevention
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Solution Overview
Problem
Uninterruptible power supply (UPS) systems face challenges in managing power quality issues like voltage sags, which cause DC offsets and transformer saturation, making it difficult to maintain stable power during disruptions.
Innovation Solution
A control system modifies the UPS power curve to depart from the normal supply curve post-sag detection, providing a predetermined level of power for a specific duration to correct anomalies, and then returns to the normal curve until source power is restored, using a system that includes power-electronic switches, storage modules, and a backup generator system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the UPS system immediately ramps up output voltage after detecting a voltage sag, then the response time is reduced, but transformer saturation occurs due to DC offset in the flux
Solution Approach 1:
The control system performs preliminary detection of voltage sags and proactively adjusts the output voltage ramp-up profile before the transformer flux can develop excessive DC offset. By anticipating the saturation risk and pre-configuring a controlled ramp-up curve, the system achieves fast response while preventing transformer saturation.
Solution Approach 2:
The system dynamically changes the output voltage parameters (ramp-up rate, duration, and magnitude) based on the detected sag characteristics. By adjusting these parameters in real-time, the system optimizes the balance between rapid response and preventing transformer flux saturation during the transition from sagged to normal voltage conditions.
2Reliability
If the UPS system provides extended power at elevated levels to correct transformer flux offset, then transformer saturation is prevented, but energy consumption increases
Solution Approach 1:
The control system implements periodic monitoring of transformer flux levels and adjusts the output power elevation duration accordingly. By using periodic feedback control, the system maintains transformer flux within safe limits while minimizing the duration of elevated power output, thus reducing unnecessary energy consumption after the saturation risk has passed.
Solution Approach 2:
The system uses feedback from flux level monitoring to dynamically adjust the power correction duration. When flux offset is detected, the system elevates power output; when flux returns to normal range, the system reduces power to standard levels. This feedback mechanism ensures energy is consumed only when necessary for saturation prevention.
3Ease of operation
If the UPS system seamlessly integrates with utility power source, then load transparency is maintained, but control flexibility during voltage sags is reduced
Solution Approach 1:
The control system dynamically adapts its behavior based on operating conditions. During normal operation, it maintains seamless integration with the utility source for load transparency. During voltage sags, it automatically transitions to flexible control modes with customized ramp-up profiles and power correction strategies. This dynamic adaptability allows the system to maintain ease of operation when needed while providing control flexibility when required.
Data Source
AI summary
A control system and method of controlling an uninterruptible power supply (UPS) system prevents a load anomaly, such as transformer DC offset, resulting from a supply disruption, such as a voltage sag, by modifying the UPS supplied power curve. The UPS supplied power curve maintains a predetermined power for a predetermined duration to cause the UPS supplied power curve to depart from normal supply curve post sag detection. Following the predetermined duration, the UPS supplied power curve is conformed to the normal power supply curve until restoration of the source power supply or engagement of a secondary power source.