Transformer Flux Prediction to Prevent Saturation During Voltage Transients
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Solution Overview
Problem
Transformers experience saturation during fast, dynamic voltage changes, particularly in grid simulators and grid-forming converters, due to limited magnetic core capacity and inadequate control systems that fail to prevent unfavorable transients.
Innovation Solution
A predictive control method that estimates and corrects the magnetic flux trajectory during transient events, using a reference mathematical model to anticipate and prevent saturation by injecting a correction signal into the transformer's primary winding, thereby maintaining the flux within operational limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional control systems are used to control instantaneous angle of voltage phase, then the system operates normally under steady state conditions, but transformer saturation occurs during fast voltage changes
Solution Approach 1:
The control system performs preliminary evaluation of the prospective flux trajectory before the voltage change is applied. By predicting the flux path using a mathematical model and checking it against saturation limits in advance, the system can prepare corrective actions before saturation occurs, rather than reacting after the fact.
Solution Approach 2:
The system uses feedback from the estimated actual flux value to generate corrective voltage commands. The feedback loop continuously monitors the flux state and adjusts the voltage phase angle in real-time to keep the flux within operational limits during fast transients.
2Measurement precision
If closed loop flux control is implemented, then flux can be balanced during steady state, but the control performance is limited by reaction time and accuracy
Solution Approach 1:
By evaluating the prospective flux trajectory in advance using a mathematical model, the system determines the necessary corrective actions before the transient occurs. This predictive approach eliminates the delay inherent in traditional reactive feedback control, as the correction is prepared beforehand based on predicted flux behavior.
Solution Approach 2:
The system dynamically adjusts the voltage phase angle based on the predicted flux trajectory. Rather than using fixed control parameters, the control strategy adapts in real-time to the specific transient conditions, optimizing the corrective action for each fast voltage change event.
3Reliability
If additional windings or converters are added to control flux before switching, then transformer saturation can be prevented, but device complexity increases
Solution Approach 1:
The system uses feedback from the estimated actual flux value to generate corrective voltage commands through the existing primary winding. This approach prevents saturation using the same hardware already present in the system, eliminating the need for additional windings or auxiliary converters.
Solution Approach 2:
The transformer's own primary winding and control system are used to prevent its own saturation. The control system leverages the existing components to generate corrective voltage commands that balance the flux, making the system self-sufficient without requiring external assistance from additional windings or converters.
4Object-generated harmful factors
If non-simultaneous switching is employed in multiphase converters, then inrush currents can be avoided, but this is not acceptable for grid simulator applications requiring arbitrary time instance switching
Solution Approach 1:
The control system continuously monitors the flux state and dynamically adjusts the voltage phase angle for each phase based on real-time feedback. This allows all phases to be switched simultaneously at any time instance while the feedback loop prevents inrush currents by ensuring favorable flux conditions are maintained throughout the switching event.
Solution Approach 2:
Rather than using fixed switching sequences, the system dynamically adjusts the voltage characteristics during the switching transient. The control strategy adapts the voltage phase angle and magnitude in real-time to achieve favorable flux trajectories, enabling flexible switching at arbitrary time instances without inrush currents.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents transformer saturation during dynamic voltage changes, allowing for higher voltage change magnitudes and dynamic operations without interrupting regular system operation, and ensures accurate tracking of voltage trajectories in demanding applications like grid simulators.
Implementation Method 1
A predictive control method that estimates and corrects the magnetic flux trajectory during transient events, using a reference mathematical model to anticipate and prevent saturation by injecting a correction signal into the transformer's primary winding
Data Source
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AI summary
The invention relates to a predictive control method For preventing saturation of a transFormer (TR) during fast voltage changes by correction of magnetic flux of the transFormer (TR), said transFormer (TR) having a primary winding with a power electronic converter (PEC) and a secondary winding, by estimating or measuring a primary signal (ii), including a primary voltage on the primary winding of the transFormer (TR) and optionally a primary current on the primary winding of the transFormer (TR), and injecting a correction signal including a correction voltage, into the primary winding of the transFormer (TR) so as to prevent saturation of the transFormer (TR). The invention also relates to a control system For preventing saturation of a transFormer (TR) during fast voltage changes by controlling the magnetic flux of the transFormer (TR), said transFormer (TR) having a primary winding with a power electronic converter (PEC) configured For receiving a correction signal U** and a secondary winding connected to a load.