A lot of industrial facilities with Cogeneration Heat and Power (CHP) exists working electrically as Distributed Generation (DG). In these utilities the cogeneration unit operate in paralell with network, but several times due to electrical disturbances, islanding operation mode is chosen. This mode is activated when disturbances appeared or are expected to appear in the network. During islanding mode both facilities and receivers are affected by the low electrical stability of the own generation. Stability disturbances are mainly referred both frecuency and voltaje stability. Disturbances also appears in the moment of the reconnection from islanding to normal operation mode. In order to avoid these inconvenients between rigid network connection and islanding operation mode an alternative solution is approached in this document, is the so-called Adaptative Rigid System (ARS). Through this system we can electrically move far away enough from network to disturbances do not affect the operation of our Plant. On the other hand we can keep the electrical stability provided by the external network. To conclude we will describe the advantages on this (ARS) system against normal operation modes.