Synchronverter Control for Unbalanced Grid Oscillations
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Solution Overview
Problem
Standard inverters exhibit low inertia, leading to adverse grid conditions during faults or load changes, and generic synchronverters are unable to provide safe and reliable operation during unbalanced grid conditions, resulting in excessive current generation and power oscillations.
Innovation Solution
A system for synchronverter power control that includes a power reference generator, a synchronverter control unit, and an active and reactive power control unit to regulate current and eliminate power oscillations and harmonics by generating an electromotive force vector and processing active and reactive power, coupled with a current limiter to prevent overcurrent generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If generic synchronverters are used to improve grid support, then inertia is increased, but during unbalanced grid conditions currents exceed nominal values and power oscillations occur
Solution Approach 1:
The control system continuously monitors terminal voltage and current measurements, and uses feedback loops to adjust the EMF vector and current references. The active and reactive power control units receive feedback from measurements and adjust control signals to eliminate power oscillations and keep currents within nominal limits during unbalanced conditions.
Solution Approach 2:
The system dynamically changes control parameters including the EMF vector magnitude and angle, current references, and power setpoints based on grid conditions. During unbalanced conditions, the control unit adjusts these parameters to eliminate oscillations and prevent current exceedance while maintaining nominal operation during balanced conditions.
2Device complexity
If standard inverters are used, then device complexity is low, but inertia is insufficient leading to worse grid conditions during transients
Solution Approach 1:
The synchronverter controls its own output by generating internal voltage and frequency references based on grid measurements, behaving like a synchronous generator. The control system self-regulates active and reactive power output, current magnitude, and voltage waveform without requiring complex external control infrastructure.
3Duration of action of moving object
If synchronverters operate during unbalanced faults, then continuous power supply is maintained, but safe and reliable operation cannot be ensured
Solution Approach 1:
The control system dynamically adapts its behavior based on real-time grid conditions. During unbalanced faults, the control unit detects the abnormal conditions and dynamically adjusts control parameters including current limits, power setpoints, and EMF vector to eliminate oscillations and prevent current exceedance, allowing continuous safe operation.
Data Source
AI summary
Methods and systems for a synchronverter power control during unbalanced grid conditions is disclosed. The system includes a synchronverter coupled with a power supply grid, a power reference generator, configured to receive a terminal voltage measurement vector vt and a current measurement vector i from the synchronverter, and generate an active power Pf and a reactive power Qf, a synchronverter control unit connected to the power reference generator and configured to process the active power Pf and the reactive power Qf and generate an electromotive force (EMF) vector e, and an active and reactive power control unit, connected between the synchronverter control unit and the synchronverter, configured to receive the electromotive force (EMF) vector e and the terminal voltage measurement vector vt, and regulate the current measurement vector i to eliminate power oscillations and current harmonics in the synchronverter during unbalanced grid conditions.