Power Converter LVRT Control via DC Source Adjustment
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Solution Overview
Problem
Conventional power conversion systems disconnect from the utility grid during low voltage ride through (LVRT) events, causing instability and frequent reconnection issues, which can lead to widespread power disruptions.
Innovation Solution
A power converter system that includes a controller to determine the occurrence of LVRT events and adjust the DC power source to a second operating point, allowing it to remain connected and provide stable power without disconnection, using a combination of DC-to-DC converters and DC-to-AC inverters to manage voltage and current responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power conversion systems disconnect during LVRT events, then the system protects itself from voltage instability, but grid stability deteriorates due to frequent disconnection and reconnection
Solution Approach 1:
The patent introduces a power converter as an intermediary device between the DC power source and the utility grid. This converter includes voltage and current controllers that mediate the interaction during LVRT events, allowing the system to remain connected while protecting the DC power source by controlling the current injection into the grid during voltage sags.
Solution Approach 2:
The patent changes the operating parameters of the power converter during LVRT events. The controller adjusts the current reference and voltage regulation parameters dynamically in response to grid voltage conditions, enabling the system to maintain connection while adapting to the changed grid conditions without causing instability.
2Stability of the object's composition
If conventional power conversion systems remain connected during LVRT events, then grid stability is maintained, but the DC power source may be damaged from excessive current
Solution Approach 1:
The patent implements feedback control through voltage and current controllers that continuously monitor grid voltage and adjust the power converter output accordingly. During LVRT events, the current controller uses feedback from voltage measurements to limit current injection, protecting the DC power source while maintaining grid connection.
Solution Approach 2:
The patent makes the power converter dynamic by enabling real-time adjustment of operating characteristics during LVRT events. The controller dynamically changes the current reference and voltage regulation based on instantaneous grid conditions, allowing the system to adapt its behavior to protect the DC power source while supporting grid stability.
3Reliability
If the power converter limits current during LVRT events, then the DC power source is protected, but the power output decreases
Solution Approach 1:
The patent applies partial action by limiting the current to a safe level during LVRT events rather than completely shutting down. The current controller allows sufficient current flow to protect the DC power source while maintaining enough power output to support critical grid loads and maintain stability, accepting temporary reduction in power as necessary for protection.
Data Source
AI summary
Embodiments of the invention can provide systems, methods, and apparatus for operating a power converter. According to one embodiment, a system for operating a power converter can be provided. The system can include a direct current (DC) power source with an output electrically coupled to an input of the power converter. The system can also include a controller operable to modify the performance of the DC power source through the power converter. As part of this modification, the controller can determine whether a low voltage ride (LVRT) event exists in a load and can adjust the DC power source when a LVRT event occurs.