Modelling and techno-economic analysis of microgrid applications

98 Z REE N°3/2017 LES MICROGRIDS (PARTIE 2)DOSSIER 2 Defining microgrids Microgrids are local, small scale grou- pings of generating sources, storage sys- tems and loads, capable of operating in parallel with or independently from the main grid, as shown in figure 1. The main drivers are: generation such as solar and wind, to meet local demand; - rity, by local control of supply; in terms of cost savings by means of energy savings and avoiding costly transmission/distribution infrastructure investments. Microgrids in general display the fol- lowing characteristics and requirements. They are capable of islanded operation and parallel operation with the grid. They are governed by autonomous control sys- tems, both in terms of power (short term stability: transient effects, voltage and fre- quency control) and in terms of energy (long term stability: energy balancing, secondary and tertiary frequency control). They normally have a single point of inter- connection with the grid, which enables bidirectional power flow from and to the microgrid. They generally include more than one generating source of different types, and rely on storage technologies. There are different key types o