Converter Voltage Angle Control Under Current Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power electronic devices in electricity networks face limitations in current capability, leading to disrupted grid forming capabilities under fault conditions, especially when current limitations are necessary, and it is difficult to predict system recovery post-fault.
Innovation Solution
A converter control system that includes a grid forming control with a current controller, a voltage controller emulating a physical synchronous machine, and an angle and amplitude control for the voltage reference to manage current limits and ensure rapid restoration of grid forming functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current limitation is applied to protect converter capability, then converter current capability is preserved, but grid forming capability is disrupted
Solution Approach 1:
The converter control dynamically adjusts the voltage reference angle based on the difference between current reference and current reference limit. This dynamic adjustment allows the system to adapt its operating point in real-time, enabling the converter to maintain grid forming capability while operating within current limits during fault conditions.
Solution Approach 2:
The invention changes the voltage reference angle parameter to minimize the difference between current reference and current reference limit. By modifying this parameter, the system restores grid forming capability while respecting converter current constraints, resolving the contradiction between current protection and grid forming function.
2Adaptability or versatility
If voltage reference angle is controlled to restore grid forming capability, then grid forming functionality is restored, but voltage runaway may occur
Solution Approach 1:
The converter control continuously monitors the difference between current reference and current reference limit, and uses this feedback to adjust the voltage reference angle. This closed-loop feedback mechanism ensures that voltage adjustments are made progressively and controllably, preventing voltage runaway while restoring grid forming capability.
3Reliability
If converter operates under fault conditions with current limits, then converter protection is ensured, but system recovery time is extended
Solution Approach 1:
The system prepares for recovery by continuously adjusting the voltage reference angle during the fault condition to minimize the difference between current reference and current reference limit. This preliminary action ensures that when the fault clears, the converter is already positioned to quickly restore full grid forming capability, reducing overall recovery time.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to a converter (1) with a converter control (13). According to the invention, the converter control is configured to provide a voltage reference (Vref) having an amplitude and an angle, process said voltage reference to obtain a current reference (Iref) to control a converter current, replace said current reference by a current reference limit (Ilim) if said current reference exceeds said current reference limit, and to control said angle of said voltage reference to minimize a difference between said current reference and said current reference limit if said current reference exceeds the current reference limit.