Optimal location of PWM based series compensator in a power system

•Damping of inter-area oscillations using PWM based series compensator.•Introducing a new dynamic performance index to optimal location of PWMSC.•Optimization of the PWMSC damping controller parameters to improve dynamic stability.•Results show that the proposed index is efficient for damping the oscillations.

This paper proposes a new approach for optimal placement of PWM based Series Compensator (PWMSC) in large power systems. The proposed approach is based on the Selective Modal Analysis (SMA) and dynamics index to damp out the inter-area oscillation modes. For this reason, first, SMA is used to calculate the low frequency modes of oscillation, and then Most Dominant Line (MDL) Table based on the dynamic index is proposed which shows the influence of active power flows of the transmission lines on inter-area modes of the power system. The parameters of the PWMSC damping controller are designed by optimization based approach for the purpose of damping inter-area oscillations in practical system. Optimal PWMSC placement is validated by comparing different candidate placements based on the total damping that they provide for system. The effectiveness of the proposed method is demonstrated on the 16-machine five-area power system for various network conditions.