Energy policies along with technological advancements in power electronics have allowed a high penetration of photovoltaic installations. To normalize grid connections, in particular for solar photovoltaic (PV) installations, an arrangement of requirements have been set as a grid code to prove that this penetration can provide support and fully control during both steady-state and transient conditions of the grid. In this paper, a control system for a PV installation connected to the grid is developed to accomplish the requirements raised in the 2010 draft version of the Spanish grid code P.O. 12.2. Control loops for steady-state conditions as well as transient conditions (voltage dips, swells, and frequency control) have been implemented. Simulations have been performed using PSCAD/EMTDC™ program and supported by field tests of an existing PV installation in Spain using the voltage dip generator.

Detection of unintentional islanding is critical in microgrids in order to guarantee personal safety and avoid equipment damage. Most islanding detection techniques are based on monitoring and detecting abnormalities in magnitudes such as frequency, voltage, current and power. However, in normal operation, the utility grid has fluctuations in voltage and frequency, and grid codes establish that local generators must remain connected if deviations from the nominal values do not exceed the defined thresholds and ramps. This means that islanding detection methods could not detect islanding if there are fluctuations that do not exceed the grid code requirements, known as the non-detection zone (NDZ). A survey on the benefits of islanding detection techniques is provided, showing the advantages and disadvantages of each one. NDZs size of the most common passive islanding detection methods are calculated and obtained by simulation and compared with the limits obtained by ENTSO-E and islanding standards in the function of grid codes requirements in order to compare the effectiveness of different techniques and the suitability of each one.