Abstract

In the event of a power outage, the ability to restart parts of the electricity grid independently is a cricitcal aspect of modern power system resilience. This process involves two key concepts: black-start and islanding operation. Black-start refers to the capability of a power plant to start without relying on external electricity from the main grid. Once initiated, this allows for islanding operation where a section of the electricity grid is intentionally separated and operated as a self-sufficient isolated system. This study addresses the challenge of maintaining power system stability and quality during the initial stages of such a scenario. It investigates how different generation sources, a hydropower plant and a combined heat and power plant (CHP), affect system performance when supplying a municipality’s critical infrastructure. Central to the analysis is the evaluation of various loading strategies and their impact on the stability parameters: frequency, voltage and rotor angle deviation.

The methodology relies on simulations employing Simulink models developed to capture the behavior of the specific power plants and local grid. Results show that both the hydropower and CHP plants can maintain acceptable stability and power quality under island operation. However, the CHP plant demonstrates greater robustness due to higher relative generation capacity in the model. The choice of loading strategy significantly affects stability and transient behavior: strategies with gradual, time-separated loading yield smoother system responses and lower frequency drops. The study concludes that system configuration and load management are crucial for reliable island operation and that further optimization of control strategies is essential to enhance resilience against disturbances in isolated microgrids.