This article addresses the voltage stability issue in a power system with constant power loads (CPLs) during line failures, particularly in harbor crane systems. The study proposes a comprehensive model of the grid-side converter (GSC) while simplifying the machine-side converter (MSC) as a CPL. The proposed model shows how input admittance behaves as a negative incremental, growing voltage instability on the load bus. The study uses Nyquist-based stability analysis to address voltage stability issues caused by double-circuit line failures and negative incremental input admittance. It investigates the feasibility of creating a phase-locked loop (PLL) for such grid disturbances and explores the integration of a static VAR compensator (SVC) with a battery energy storage system (BESS) on the load bus if there is no equilibrium point in the $P_e - \delta$ curves during line failure. The article includes detailed impedance modeling of the MSC and GSC, voltage stability analysis at the load bus, and transient voltage stability analysis during line failures. It also discusses the impact of PLL bandwidth adjustment on grid strength and power, and the integration of BESS-SVC to enhance transient stability. The study concludes with experimental validation using a hardware-in-loop (HIL) test bench, demonstrating the effectiveness of the proposed methods in maintaining voltage stability during line failures.This article addresses the voltage stability issue in a power system with constant power loads (CPLs) during line failures, particularly in harbor crane systems. The study proposes a comprehensive model of the grid-side converter (GSC) while simplifying the machine-side converter (MSC) as a CPL. The proposed model shows how input admittance behaves as a negative incremental, growing voltage instability on the load bus. The study uses Nyquist-based stability analysis to address voltage stability issues caused by double-circuit line failures and negative incremental input admittance. It investigates the feasibility of creating a phase-locked loop (PLL) for such grid disturbances and explores the integration of a static VAR compensator (SVC) with a battery energy storage system (BESS) on the load bus if there is no equilibrium point in the $P_e - \delta$ curves during line failure. The article includes detailed impedance modeling of the MSC and GSC, voltage stability analysis at the load bus, and transient voltage stability analysis during line failures. It also discusses the impact of PLL bandwidth adjustment on grid strength and power, and the integration of BESS-SVC to enhance transient stability. The study concludes with experimental validation using a hardware-in-loop (HIL) test bench, demonstrating the effectiveness of the proposed methods in maintaining voltage stability during line failures.