Converter Current Control for Low-Voltage Ride-Through Stability
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Solution Overview
Problem
Power supply systems experience poor stability and safety due to converter oscillations when connected to power grids with varying impedance, leading to misjudged reactive current adjustments that exacerbate voltage fluctuations during failures.
Innovation Solution
A power supply system with a drive control circuit that adjusts converter output current based on the duration of previous voltage ride-through events, using predefined or calculated current values to match grid impedance and stabilize voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the converter increases reactive current output to maintain voltage during grid failure, then voltage stability is improved, but circuit oscillation increases and safety decreases
Solution Approach 1:
The control method performs preliminary detection of grid impedance before grid failure occurs. By obtaining the impedance value in advance and using it to calculate the appropriate reactive current magnitude when failure happens, the system avoids oscillatory adjustments and directly implements the correct current level, thereby maintaining voltage stability while ensuring system safety.
Solution Approach 2:
The system continuously monitors grid voltage and detects failures in real-time. When voltage deviation exceeds a threshold, the control method activates reactive current adjustment based on pre-detected impedance values. This feedback mechanism ensures the converter responds appropriately to grid conditions, maintaining stability without causing harmful oscillations.
2Measurement precision
If the converter adjusts reactive current based on real-time impedance detection, then voltage control precision is improved, but system complexity and detection costs increase
Solution Approach 1:
The method performs impedance detection and calculation before grid failure occurs, storing these values for immediate use during emergencies. This preliminary action eliminates the need for complex real-time impedance calculation during critical moments, reducing system complexity while maintaining high precision through pre-measured values.
Solution Approach 2:
The control system uses the pre-detected impedance values to automatically calculate and adjust reactive current without requiring external intervention or complex real-time computations. The system serves itself by utilizing stored impedance data to make immediate, precise adjustments during grid failures, simplifying the control architecture.
Data Source
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AI summary
This application provides a power supply system and a conversion method. The power supply system includes a power generation apparatus, a converter circuit, and a drive control circuit. The drive control circuit may be configured to: when a power grid fails, control, based on duration of previous low voltage ride-through, the converter circuit to increase a value of a current to be output to the power grid from a first operating current value to a current with a low voltage ride-through current value, to increase a voltage value at an output end of the converter circuit. Herein, the previous low voltage ride-through is latest low voltage ride-through. In this application, the system can control, based on duration of previous voltage ride-through, a current to be output by the converter circuit to the power grid, to reduce circuit oscillation, with a simple structure, a simple control method, and high safety.