Grid Stabilization via Symmetrical Component Decomposition
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Solution Overview
Problem
Existing methods for network stabilization, such as those used in DE 10 2007 005 165 A1 and DE 10 2006 054 870 A1, are not optimally applicable at the low-voltage level and fail to effectively support both symmetrical and asymmetrical network errors, as they generate compensation currents unnecessarily and are not adaptable to different network guidelines.
Innovation Solution
A method that decomposes network voltages into positive and negative system components, determines compensation currents as a vector sum of these components, and feeds them back into the network, using reference values determined by mean values or low-pass filters to stabilize the network without reacting to permissible asymmetries, and can adapt to different network guidelines and impedance conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing methods generate compensation currents based on negative system components, then asymmetrical network errors are supported, but unnecessary compensation currents are generated for permissible asymmetries and symmetrical errors are not supported
Solution Approach 1:
The patent segments the network voltage into symmetrical components (positive sequence) and asymmetrical components (negative sequence) using Fortescue transformation. This segmentation allows the control system to selectively compensate only for asymmetrical errors when they exceed permissible limits, rather than generating compensation currents for all deviations including permissible asymmetries and symmetrical errors.
Solution Approach 2:
The patent implements dynamic control by continuously monitoring the negative sequence voltage component and only activating compensation when it exceeds a configurable threshold. This dynamic approach allows the system to adapt to varying network conditions, supporting asymmetrical errors when present while avoiding unnecessary compensation currents during normal operation with permissible asymmetries.
2Reliability
If network support methods are designed for specific voltage levels, then they work effectively for that level, but they are not adaptable to different voltage levels and network guidelines
Solution Approach 1:
The patent creates a universal network support method that can be applied across different voltage levels (low-voltage and medium-voltage) by using standardized symmetrical component analysis and configurable control parameters. The method adapts to different network guidelines through adjustable threshold values and compensation characteristics, making it versatile for various network conditions without requiring level-specific redesign.
Solution Approach 2:
The patent enables adaptation to different voltage levels and network guidelines by configuring parameters such as the negative sequence voltage threshold, compensation current limits, and characteristic curves. These parameter changes allow the same fundamental method to be effectively applied across different network contexts while maintaining optimal performance for each specific application.
3Stability of the object's composition
If compensation currents are fed in for all negative system components, then network stability is improved, but energy loss increases and permissible asymmetries are incorrectly treated as errors
Solution Approach 1:
The patent applies partial action by selectively compensating only for the asymmetrical component of network voltage (negative sequence) when it exceeds a permissible threshold, rather than compensating for all deviations. This approach provides sufficient network support for actual asymmetrical errors while avoiding energy waste on permissible asymmetries and symmetrical variations that do not require compensation.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the negative sequence voltage component and adjusting compensation current injection accordingly. The system feeds back the measured asymmetry level to the control algorithm, which modulates the compensation magnitude to match the actual network need, thereby maintaining stability only when necessary and reducing energy loss during normal operation.
Data Source
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AI summary
A grid support method, the grid support being carried out by feeding compensation currents, comprises the following steps: determining an actual grid state (step 100), breaking down the voltages determined for determining the actual grid state into positive sequence components and negative sequence components (step 101), determining the positive and negative sequence components of a compensation current as functions of the deviations of the positive and negative sequence components of the grid state from reference values (steps 102, 103) and feeding a compensation current as the vector sum of the symmetrical components thereby obtained.