Modeling an isolated hybrid wind-diesel power system for performing frequency control studies. A case of study: San Cristobal Island, Galapagos–Ecuador

Abstract

From a technical and ecological point of view, standalone wind-diesel power generation has been proven to be one of the most effective solutions in electrification in remote populated locations. However, some technical aspects that characterize those systems such as the small size of conventional power generators, high share of wind energy, low consumption levels, and the lack of energy storage equipment, might make the operation and control tasks difficult due to the low stability margin. A real case that supports the previous statement is the San Cristobal wind-diesel power system (Galapagos Islands-Ecuador), whose undoubted environmental and economic benefits are notoriously contrasted by certain technical challenges that grid operators have to deal with. During the windiest season of 2015, many blackouts were reported on the island. These were originated by the trip of frequency relays of generation units whose causes are still unknown. In order to provide an analysis tool that allows to study the dynamics of most relevant variables of systems with these characteristics during a power contingency and to identify the possible causes that lead to a certain frequency event, this paper proposes a modeling procedure based on the load frequency control scheme, within the primary frequency regulation time-frame, along with its implementation in MATLAB/Simulink®. The complete model is validated by using real data measured in field tests in the island power system as well as technical information provided by the grid-operators.