Islanded Operation of Distribution Grid with High Penetration of Renewable Energy Sources 28 de xul. de 2022

Renewable energy sources are being connected not only to transmission but also to distribution
grids. Medium voltage distribution grids are meshed grids that are operated radially. Their
reliability is determined by their reconfiguration capability. However, portions of medium
distribution grids can lack of supply in case of specific disturbances or abnormal operating
conditions.
Al alternative to the lack of supply in medium voltage distribution grids is the use of the available
renewable energy resources. The feasibility of the use of renewable energy sources depends
on their ability to control both voltage and frequency to guarantee the quality of the electrical
supply.
This contribution will show from real life tests [1] that stable operation islanded operation of
medium voltage distribution grids is not feasible due to the limited control capability of
renewable energy sources connected through power electronic converters under grid feeding
control scheme. It will show that medium voltage distribution grids can run properly while
isolated from the main grid if they incorporate battery energy storage systems. Records of real
life tests will prove it.
In addition, this contribution discusses the conditions por parallel operation of several battery
energy systems under grid forming control scheme with inverter based generation under grid
feeding schemes [2]. Stability conditions will be drawn.