Depletion of fossil fuel, global warming, and their environmental pollution clarify the importance of renewable energy sources (RESs). However, high penetration of RESs decreases power systems inertia, hence, the system becomes more sensitive to disturbances. This results in problems with frequency control because it increases the rate of change of frequency and may lead to load shedding or tripping of generating units. This paper aims at introducing a comprehensive survey of the effects of the increase in RESs on power system inertia and frequency. Different models of wind-driven and photovoltaic systems used for frequency control studies have been introduced. The up-to-date effective frequency regulation methods which can be used with highly RESs penetrated power systems have been revised and compared. These methods include virtual inertia-based methods depending on energy storage devices, de-loading of renewable energy sources, various inertial response techniques and demand response at load section including under frequency load shedding and electric vehicles. Extensive comparisons among these methods have been carried to guide power system designers, operators, researchers and grid codes taskforces in proper incorporation of RESs for frequency regulation of power systems