The control of the electrical frequency is one of the major problems for stabilizing the power grid and improving its efficiency. The environmental pollution and cost of nuclear and fossil fuel power plants has raised the use of Renewable Energy Source (RES) whose power supply (wind or solar flux) fluctuates with the weather. The fluctuations of the power supply together with those of the demand load create fluctuation in the frequency difficult to control. One way to stabilize this electrical frequency is the use of Dynamic Demand Control (DDC). The DDC is a low-cost technology that uses the properties of a specific group of electrical appliances to provide an effective energy storage system on the electricity grid. The DDC provides also frequency regulation by controlling the demand side of the grid, reducing the load when the grid is under stress. In this work, we study how a fraction of users controlling their demand dynamically (DDC users), adjusting their power consumption to the load of the grid, allow to reduce the power grid fluctuations. We use a model of the power grid where power plants are aggregated and consumers have an infinite number of devices of a fixed power that switch on and off randomly. We show that a small fraction of DDC users is sufficient to substantially reduce the power grid frequency fluctuations.