Review, analysis and recommendations on recent guidelines for the provision of ancillary services by Distributed Generation

The increased integration of Distributed Generation (DG) in electricity networks makes the provision of ancillary services imperative. In the last few years several national and international standards-guidelines have been published stating connection rules for generators, including requirements related to ancillary services. However, the requirements are not always harmonized and at some points present contradictions. This paper provides an overview of key requirements for the provision of ancillary services by distributed generation. A comparative analysis is performed, which identifies contradictions and requirements that are not thoroughly defined. Attention is drawn to potential problems due to specific “unclear” requirements, such as the Q(U) control at asymmetric conditions, which is analyzed through simulations. Furthermore, promising functionalities for future requirements are discussed.