A Static Synchronous Series Compensator (SSSC) Model with H-Bridge Multilevel Inverter

We developed a Static Synchronous Series Compensator (SSSC) model using Simulink, where the inverter section implements an H-bridge multilevel inverter topology with carrier phase-shifted PWM (SPWM) modulation strategy. The simulation environment replicates a 35kV transmission system configuration with more than three nodes, with the SSSC operating in impedance compensation control mode. Below we present and analyze simulation results for both capacitive and inductive compensation scenarios. First, we constructed the SSSC model in Simulink and configured all system parameters. The inverter control implementation uses carrier phase-shifted PWM modulation to achieve precise current regulation through phase-disposed triangular carriers for different H-bridge modules. The 35kV transmission line simulation incorporates realistic system constraints with multi-node analysis to evaluate compensation effectiveness. Under capacitive compensation conditions, simulation results demonstrate that the SSSC successfully improves line power factor through capacitive reactance compensation, significantly reducing reactive power losses. The control algorithm maintains voltage stability by injecting capacitive VARs, with system voltage profiles showing marked improvement across all monitored nodes. For inductive compensation scenarios, the SSSC enhances power factor through inductive reactance compensation, increasing reactive power injection into the system. This proves particularly beneficial for long-distance transmission lines, effectively reducing voltage drops and improving overall transmission efficiency. The control scheme dynamically adjusts inductive VAR injection based on line loading conditions. In conclusion, the Simulink-based SSSC model successfully demonstrates comprehensive static synchronous series compensation capabilities. Both capacitive and inductive compensation scenarios yield detailed simulation results with thorough analysis. These findings provide valuable guidance for practical power system design and operation, particularly for implementing advanced FACTS devices in modern transmission networks. The model's modular structure allows for easy parameter adjustment and control strategy optimization for different system requirements.