Electrical Load Profile Control Under Thermal Derating Limits
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Solution Overview
Problem
Existing methods for determining the course of a control size in electrical systems are inadequate as they fail to accurately predict performance and often result in overly conservative derating predictions, leading to inefficient operation and potential overheating.
Innovation Solution
A procedure and device for determining the course of a control size in an electrical system, which calculates permissible values of the control size based on output variable differences and derating functions, allowing for precise prediction of performance and prevention of overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If forward modeling is used to predict temperatures in future time intervals, then temperature prediction capability is improved, but the prediction becomes too conservative and prevents necessary load adjustments from being deduced
Solution Approach 1:
The patent inverts the conventional forward modeling approach by using backward modeling. Instead of predicting temperatures from current load and comparing with derating curves, the method determines the maximum permissible load by working backward from the derating curves and thermal model. This inversion eliminates the conservative bias inherent in forward modeling while maintaining accurate temperature prediction capability.
Solution Approach 2:
The patent implements feedback by iteratively adjusting the predicted load based on the thermal model responses. The method compares the thermal model output with derating curves and adjusts the load prediction accordingly, ensuring that the predicted load profile respects thermal constraints while maximizing operational efficiency. This feedback mechanism resolves the contradiction by making the prediction adaptive rather than statically conservative.
2Measurement precision
If iterative forward modeling with different load cases is performed until limit temperature is met, then accurate temperature prediction is achieved, but the computational effort becomes very laborious
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing thermal model responses for various load cases. Instead of performing iterative forward modeling at runtime, the method prepares thermal characteristics in advance and uses them to directly determine the maximum permissible load profile. This preliminary preparation eliminates the need for computationally intensive iterative calculations during operation.
Solution Approach 2:
By inverting the modeling approach to work backward from thermal constraints rather than forward from load conditions, the patent avoids the iterative computational loop entirely. The backward method directly computes the maximum permissible load that satisfies thermal limits without requiring repeated simulations with different load cases.
3Reliability
If derating procedures are implemented as self-protection measures, then component protection is improved, but the operating state must be reduced and efficiency decreases
Solution Approach 1:
The patent implements preliminary action by determining the maximum permissible load profile in advance, before thermal constraints are violated. By predicting the optimal load profile that respects thermal limits from the outset, the system avoids the need for reactive derating measures. This preliminary planning allows the system to operate at maximum efficiency while inherently protecting components from overheating.
Solution Approach 2:
The method uses feedback by continuously monitoring the actual temperature and comparing it with the predicted temperature profile. When deviations are detected, the system adjusts the load profile accordingly, ensuring that component protection is maintained while minimizing unnecessary derating. This feedback mechanism allows the system to operate efficiently while providing reliable component protection.
Data Source
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AI summary
The invention relates to a method for determining a value profile of a controlled variable of an electrical system. Differences between predetermined values of an output variable at an end time and a determined value of the output variable at the end time are determined. A value profile of the controlled variable in the time interval is predetermined, the value profile being dependent on an end value at the end time and being determined uniquely by the specification of the end value. Allowed values of the controlled variable are determined such that, when the electrical system is activated, the value of the output variable at the end time is equal to the determined difference. A curve of the allowed values of the controlled variable is determined on the basis of the allowed values of the controlled variable. A point of intersection of the determined curve and a predetermined derating function is determined. The value profile of the controlled variable within the time interval is determined as the value profile for which the end value of the value profile assumes the value of the controlled variable at the point of intersection.