D-STATCOM for Voltage Sag and Swell Correction with Implementation Strategies

D-STATCOM for Sag and Swell Correction

Voltage sags and swells represent critical power quality disturbances that can severely impact sensitive electrical equipment. The Distribution Static Synchronous Compensator (D-STATCOM) serves as an advanced flexible AC transmission system (FACTS) device designed to effectively mitigate these voltage irregularities through dynamic reactive power compensation.

Implementation-wise, a D-STATCOM operates as a voltage source converter (VSC) connected to the distribution network through a coupling transformer. The core algorithm typically involves dq0 transformation for three-phase voltage/current decomposition, where the control system monitors instantaneous voltage magnitudes and phase angles. During voltage sags, the D-STATCOM injects capacitive reactive power (positive Q-injection) to elevate voltage levels, while during swells, it absorbs inductive reactive power (negative Q-absorption) to suppress overvoltages.

The control architecture employs a dual-loop strategy: an outer voltage control loop using PI regulators to maintain PCC voltage references, and an inner current control loop for precise current tracking. PWM modulation techniques (typically space vector PWM) generate switching signals for IGBT/MOSFET converters, with carrier frequencies ranging from 2-10 kHz for optimal harmonic performance. Code implementation often involves Clarke/Park transformations for abc-to-dq conversion, with phase-locked loops (PLL) for grid synchronization.

By implementing real-time voltage regulation through sophisticated control algorithms, D-STATCOMs significantly enhance power system reliability for industrial and commercial applications, reducing equipment malfunctions and improving overall power quality metrics including THD reduction and voltage stability indices.