Damping of power system oscillations with unified power flow controller (UPFC)

A comprehensive approach to the design of UPFC controllers (power-flow controller, DC-voltage regulator and damping controller) is presented. Studies reveal that damping is adversely affected by the incorporation of a DC-voltage regulator. Investigations were carried out to understand the relative effectiveness of modulation of the UPFC control signals m_B, δ_B, m_E and δ_E on damping of the system oscillations, using a controllability index. A dual damping controller based on simultaneous modulation of UPFC control signals m_B and δ_E is proposed. Investigations reveal that alternative damping controllers (damping controller m_B, damping controller δ_E and dual damping controller) provide robust dynamic performance under wide variations in loading condition and system parameters.