Symbiotic operation of wind and PV farms connected to the high voltage grid

Large renewable power plants connected to the high-voltage network have the potential to make an important contribution to the grid's reactive power management. This is especially true when rather than using a predetermined Q characteristic, the system operator can control the power plant's reactive power output via a direct interface. However, the intermittent nature of the primary resources and today's reactive power requirements inhibit the permanent availability of reactive power from wind and photovoltaic (PV) power plants. This study shows that a synchronized, so-called symbiotic control of PV and wind power plants can vastly increase their capability of fulfilling reactive power demands. This is demonstrated by simulating the properties of a real PV and wind farm located in Germany. Furthermore, generating units coupled to the grid via power electronics have an even larger potential of providing reactive power when their P-Q characteristics are adapted. On the downside, this can lead to an undesired coupling of reactive and active power control in the grid. A symbiosis of wind farms and PV parks can once again improve this situation when smart power allocation methods are employed. An appropriate algorithm has been developed for this study and is tested on the above-mentioned simulation model.