Purpose: To substantiate a method for enhancing the reliability and cost-effectiveness of the insufficient power supply system in the city of Tartus by deploying distributed gas-turbine generation. Methods: 1. Analytical calculation of the availability coefficient in accordance with GOST R 27.002-2009 for three supply scenarios: exclusively from the external grid, islanded operation, and parallel operation with distributed generation. 2. Simulation of both normal and emergency operating conditions in PowerFactory and RastrWin 3, focusing on the assessment of power losses, as well as voltage and frequency variations. 3. A techno-economic evaluation of an 18 MW gas-turbine power centre employing the net discount method. Results: The results obtained demonstrate that the integration of distributed generation does not compromise reliability. The overall system availability coefficient achieves a value of 0.999, which is comparable to the baseline and exceeds the regulatory requirements. In islanded operation, voltage deviation remains within ±5%, and frequency within ±0.2 Hz. The economic calculation indicates a payback period of approximately 9 years, with a unit cost of generation of about 5 RUB/kWh. Practical significance: An optimal configuration of gas-turbine distributed generation and its interconnection scheme (20 kV, double-circuit lines 2 × 300 mm²) will enhance supply resilience for the city’s critical consumers and reduce dependence on the external power system. The findings of this study can serve as a methodological basis for modernization of power systems in other regions facing similar capacity deficits.