Frequency response of a large-scale grid-connected solar photovoltaic plant

Integrating large scale solar photovoltaic generation plants with electric power systems as a renewable energy source achieve many targets, i.e. economic, environmental and technical. These plants are classified as variable renewable energy sources which have two main attributes; variability and uncertainty. This variable nature poses challenges for an electric grid that has traditionally been powered by traditional generating resources that are relatively stable and controllable. Traditional schemes used to maintain frequency stability cannot be efficient, reliable and quick to overcome this variable generated power. Modern and adaptive schemes must be designed to handle these variable renewable energy sources (VRESs). Solar Photovoltaic Generation (SPVG) is a VRES, which has a great potential. This paper presents the results of a study of frequency stability for different sharing levels of large scale photovoltaic generation. This photovoltaic system is integrated with a test grid taking into account load type effects and different overloading levels. An algorithm for sizing positive and negative spinning reserve is proposed. This algorithm takes into consideration the scale of the photovoltaic generation plant. It will also consider the percentage of sharing and the IEEE worst case frequency limit that may prevent cascaded outage of other traditional generating units in the system.