With the penetration of DGs (DGs) in a power systems, some restrictions such as economic dispatch in non-dispatchable sources, their control technology and voltage/frequency stability may be challenging. In conventional power systems, the transient stability has been obtained by high-inertia of upstream network in all conditions; however, in modern power grids, the micro grids (MGs) which could operate in both islanded mode and grid-connected mode are taken into account to overcome this issue. AC or DC types of DGs usually connect to the loads through power electronic converters, in which for researchers, this issue has been interesting and applicable to continue. When loads have been changed, the frequency has influenced correspondingly and must not exceed the permissible range. Therefore in this paper, this intention has been studied using conventional droop controller and intelligent sliding surface approach (ISSA) to evaluate the DGs effects on load-frequency control. While two or more areas (as some individual MGs) connect to each other via a transmission line, the voltage/frequency stability and power balancing constrained may be changed, which the ISSA is hired to track the frequency changes. To examine this problem, in this paper there are three MGs operate separately to show if the load may not supply, they should connect to adjacent block. If this important concern has not considered, it may cause global black-out. The simulation results obtained by ISSA compared with droop controller method represent the superiority of proposed technique to achieve best power sharing.