Development of a small-scale generator set model for local network voltage and frequency stability analysis

The integration of numerous small-scale generators into existing local networks (e.g., a microgrid) is anticipated to impact their operation, control, and protection. In particular, maintaining voltage and frequency stability within the defined limits is more onerous and requires investigation. The effect of protective limiters and characteristics such as the genuine inertia of the generation set must be taken into consideration in stability studies in order to accurately represent the overall dynamic characteristics of local distributed generators. This paper focuses on three fundamental aspects: 1) the development of a reciprocating engine/generator set model; 2) the laboratory testing of an experimental test rig; and 3) the influence of a volts-per-hertz ratio (volts-per-hertz ratio) limiter on the generator dynamic response. The experimental procedures used to determine the genuine inertia of the test rig are described and the system responses under different scenarios are used to validate the developed model. This emphasizes the significance of excitation protective limiters such as volts-per-hertz ratio, during the stability analysis.