Changing the paradigm of distribution networks planning and operation: A systematic review of the distributed energy resources impact

Abstract

The connection of new distributed energy resources (DER) is recently being delayed by the system operators primarily due to the approach where each connection request is separately assessed. The lack of coordination between connection requests is making the process time-consuming and also creating virtual congestion in the network, hindering further investments. With the development of advanced analytical tools and increased observability, Distribution System Operators (DSOs) are starting to adopt new planning and operational approaches. Calculating a network’s hosting capacity (HC) is one of the most investigated planning concepts in modern power systems. However, HC is a conservative approach that considers worst-case scenarios, thereby limiting new connections to the network. This has created the need to develop the dynamic operating envelopes (DOE) concept. DOEs are envisioned as the concept bridging the gap between planning and operational phases, as well as an approach to test the relaxation of conservative fixed connection rules defined in national grid codes. A step further is the near real-time upgrade of DOE defined as P-Q flexibility regions, improving the previous concepts by estimating system-level service provision capabilities. The concept is based on controlling active and reactive power and, consequently, increasing system’s flexibility. The paper contributes in the form of an extensive review of modeling techniques and algorithms, defining the necessary dataset for each of the concepts and models. Furthermore, it discusses the importance of including various technical constraints. Additionally, the paper identifies necessary improvements in data collection to properly assess the value and constraints of DER providing services to the distribution system.