An Impedance-Based Stability Analysis for Constant Power Load with Line Failure
Iraklis P. Nikolakakos, Utkal Ranjan Muduli, Mohamed Shawky El Moursi, Khalifa Al Hosani, Sayed Abd El Aziz Mohamed, Tareg Ghaoud
Abstract
Modeling the grid-side converter (GSC) in detail while simplifying the machine-side converter (MSC) as a constant power load (CPL) is beneficial for voltage stability analysis at the load bus. On the ac side of GSC, Nyquist-based stability analyses are typically performed due to the presence of multiple eigen-loci. However, DC side Nyquist stability criteria lead to computing the input admittance at the ac side of GSC. This input admittance behaves as a negative incremental for the CPL operation of the connected induction motor load; thus leads to voltage instability at the load bus. This paper also addresses the voltage stability issue corresponding to double-circuit line failure. This analysis is conducted through detailed impedance modelling of the system. The feasibility of designing a phase-locked loop (PLL) for such a scenario of grid disturbances are investigated in this paper through MATLAB/Simulink environment.