This chapter shows an example of the use of the standard approach proposed in Sect. 4.5 in order to address the problem of decentralized frequency control in multi-source micro-grids. The chapter starts by showing that the standard swing frequency equation (the derivative of the frequency is equal to the power unbalance between the produced and the consumed powers) does not truly hold in the presence of high dynamics on the produced power. This promotes the use of the model of uncertain systems with high order destabilizing dynamics, such as the one studied in Sect. 4.5, in order to address this critical problem of frequency control of micro-grids. In this practical example, the uncertainties come from the decentralized nature of the solution on one hand and from the fact that the control law to be designed should be agnostic to the specific implementation and tuning of the local controllers (the droop controllers) at each generator level as well as from the unknown and unpredictable load power’s profile.