Understanding of gas engines responses to system load changes

Use of reciprocating gas engines for small, 1-3MW, and islanded power generation systems becomes more economical in comparison to gas turbine or diesel engine driven systems. This is due to increased efficiency of the gas engines, availability of the fuel gas and reduced emissions. Design of power generation systems includes transient studies carried out to understand the systems response to disturbances caused by sudden load demand changes e.g. motor starts, partial loss of generation, loss of interlinks. Usually, those studies done by software simulations, using wide range of available governor models for gas/steam turbines and diesel engines. This paper examines lessons learnt from various power generation projects when gas engines were used as main power sources. It analyses attempts to model gas engines governors and their validation using engines responses' results from factory tests. It is also reviews the project when software simulation was not deemed feasible and comprehensive onshore testing of power generation and power management system was undertaken to fine tune various operating scenarios before offshore installation. The paper is intended to aid design engineers to select and optimise power generation systems.