Voltage Sag Fault Simulation and Analysis

Voltage sag is one of the most common power quality issues in electrical power systems, typically caused by factors such as short-circuit faults, motor starting, or lightning strikes, which can lead to abnormal shutdowns or malfunctions of sensitive equipment. In power supply design, engineers need to pre-assess the system's response capability to voltage sags, and fault simulation serves as a critical method for validating and optimizing designs.

### Key Technical Aspects of Fault Simulation Transient Analysis Models: By establishing equivalent circuits of power grids, engineers can simulate the magnitude and duration of voltage sags. Commonly used tools like MATLAB/Simulink and PSCAD enable accurate reproduction of voltage waveform distortions under various fault scenarios. Code implementation typically involves defining differential equations for circuit components and using solvers like ode45 in MATLAB for transient analysis. Parametric Testing: Setting key variables such as sag depth (20%-90% of nominal voltage), duration (0.5 cycles to 1 minute), and phase angle jumps to cover typical operating conditions defined by standards like IEEE 1159. Programming approaches include creating parameter sweep scripts that systematically vary these parameters and automate simulation runs. Equipment Immunity Verification: Connecting simulation results to closed-loop models of power supplies under test to observe dynamic responses (such as UPS switching, DC/DC adjustment rates) and identify weak points like undervoltage protection thresholds. Implementation often involves co-simulation techniques where control algorithms interact with power circuit models in real-time.

### Extended Application Scenarios Renewable Energy Integration: Testing LVRT (Low Voltage Ride-Through) capability of photovoltaic inverters during grid voltage dips. Simulation code typically implements grid code requirements as conditional statements in control logic blocks. Industrial Power Design: Evaluating operational stability of equipment like variable frequency drives and PLCs under voltage sags. Modeling approaches include creating detailed semiconductor device models with thermal considerations and protection circuitry.

Simulation results directly guide hardware optimization, such as adjusting energy storage capacitor capacity or improving control algorithms, thereby reducing system failure risks. Code enhancement strategies may involve implementing adaptive control algorithms that automatically adjust parameters based on sag characteristics detected in real-time simulations.