Harmonic Compensation Controller with Passive Filter Dynamics
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Solution Overview
Problem
Existing devices and methods for compensating harmonics in high-voltage networks fail to achieve stable, highly dynamic regulation due to neglecting natural oscillations of passive filters, leading to unstable control behavior and prolonged compensation times.
Innovation Solution
The control unit models the dynamics of the passive filter, providing controller parameters to avoid natural oscillations, allowing for rapid and stable harmonic compensation within one mains period by adjusting the controller's dynamic behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the controller is given a highly dynamic characteristic to improve compensation speed, then the compensation time is reduced, but the control behavior becomes unstable due to natural oscillations of the passive filter
Solution Approach 1:
The system performs preliminary action by determining the natural oscillation frequency of the passive filter before compensation begins, and pre-calculates the compensated setpoint current that accounts for these oscillations. This allows the controller to anticipate and counteract oscillations before they disrupt stability, enabling fast response without sacrificing control stability.
Solution Approach 2:
The patent introduces an intermediary calculation step that processes the setpoint current through a specific formula (Equation 2) that incorporates the natural oscillation frequency as a mediating parameter. This intermediary transformation adjusts the control signal to account for filter dynamics, allowing the controller to achieve both high speed and stability by mediating between the raw setpoint and the actual control output.
2Stability of the object's composition
If a slower control characteristic is used to maintain stability, then natural oscillations are avoided, but the compensation time increases to more than three mains periods
Solution Approach 1:
The patent applies parameter changes by modifying the setpoint current parameter through a mathematical transformation that incorporates the natural oscillation frequency. Instead of changing the controller's dynamic characteristics or slowing down the response, the system changes the parameter (setpoint current) to account for oscillations, achieving stability while maintaining fast compensation within one mains period.
Solution Approach 2:
The system determines the natural oscillation frequency and calculates the adjusted setpoint current in advance, before the compensation process begins. This preliminary calculation allows the controller to operate at full speed without causing instability, as the oscillation effects are already accounted for in the pre-computed setpoint.
3Productivity
If the controller operates with high dynamic response, then rapid compensation is achieved, but oscillations in the passive filter cause unstable control behavior
Solution Approach 1:
The patent applies dynamics by making the control system adaptive to the passive filter's natural oscillation frequency. The controller dynamically adjusts the setpoint current based on the determined oscillation frequency, allowing it to maintain high productivity while ensuring reliability. The system is no longer static but adapts its behavior based on the filter's dynamic characteristics.
Solution Approach 2:
The system implements feedback by using the determined natural oscillation frequency to adjust the setpoint current calculation. This feedback loop ensures that the controller accounts for the filter's oscillatory behavior, maintaining both high compensation efficiency and reliable control by continuously adapting to the system's dynamic properties.
Data Source
Figure 1~3
Figure 4~5
AI summary
The invention relates to a device (1) for compensating harmonics occurring in current flows in a high voltage system (5) comprising a passive filter (2) and a controllable voltage source (3), which can be connected in a parallel connection to the high voltage system (5) by the passive filter (2); and comprising a regulator unit (4) calculating a nominal current iSoll subject to the detected harmonics, which equals the negative harmonics to be compensated, wherein the nominal current iSoll is compared to a compensation current iKomp generated by a controllable voltage source (3), thus obtaining an error variable. The error variable is conveyed by a regulator parameter (K1, K2, K3) to a control unit, the dynamic behavior of which can be adjusted, said control unit providing at its output a control voltage uKomp for the controllable voltage source (3), thus driving a compensation current uKomp preferably equal to the nominal current iSoll. In order to allow quick and stable regulation of the harmonics compensation, it is proposed that the regulator unit (4) is provided with means for modelling the dynamic of the passive filter (2), and that the means for modelling the dynamic of the passive filter (2) provide regulator parameters (K1, K2, K3), wherein, by using the regulator parameters (K1, K2, K3), the regulator unit is adjusted such that self-oscillations of the passive filter (2) are avoided.