Static Synchronous Series Compensator (SSSC) Model

The Static Synchronous Series Compensator (SSSC) is a advanced FACTS (Flexible AC Transmission System) device primarily employed for reactive power compensation in electrical transmission lines. This model demonstrates how SSSC operates by injecting a controllable series voltage in quadrature with the line current, effectively emulating a variable inductive or capacitive reactance. In typical implementations, the SSSC core component is a Voltage Source Converter (VSC) that generates the compensating voltage through PWM (Pulse Width Modulation) techniques. The VSC connects to the transmission line via a coupling transformer, with control algorithms managing the magnitude and phase angle of the injected voltage. Key functions include: - Reactive power regulation through dq-frame transformation control - Voltage stabilization using phase-locked loop (PLL) synchronization - Power oscillation damping via supplementary control signals - Dynamic impedance compensation through real-time measurement of line parameters The SSSC control system typically employs vector control strategies, where the line current is decomposed into active and reactive components using Park's transformation. This enables independent control of series compensation levels through PI controllers that adjust the converter's modulation index and phase angle. Implementation considerations include: - DC link voltage maintenance using energy balance equations - Protection systems for overcurrent and overvoltage conditions - Coordination with other power system controllers through communication interfaces This compensation technology significantly enhances transmission line stability, increases power transfer capacity, and improves overall grid reliability, making it a crucial component in modern smart grid architectures.