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With the ongoing digitalization in the energy transition and the rollout of intelligent measuring systems (iMSys) in Germany, new opportunities arise in communicating with distributed energy systems. For monitoring and telecontrolling the increasing number of distributed energy resources (DER) as well as flexible loads, the use of controlling systems in the distribution grid is gaining more importance. Therefore, different applications have been developed and basic functionalities tested in a laboratory and field environment. As a part of this progress the presented contribution focuses on the implementation of a test bench for monitoring and controlling systems named Controllable Local System (CLS) gateways. Based on the Controller Hardware-In-the-Loop (CHIL) respectively Power Hardware-In-the-Loop (PHIL) method, the test bench validates the bidirectional communication functionalities of a CLS Gateway, which is coupled with a photovoltaic inverter. The implemented test bench features a test automation which enables the conduction of multiple test scenarios concerning functionality, stability as well as resilience of a test object. Mainly this aims at investigating the suitability of such CLS gateways for field operation. Aside of the implemented test bench first test results are presented in this work. The investigated test CLS gateway has revealed a reliable transmission of measurement and control data during long-term examination. Also, frequent power interruptions can lead to failure of functionalities.

The integration of decentralized renewable energy systems into our distribution networks leads to a need of more detailed information about local network structure and state estimation down to the low voltage level [1]. This enforces the transformation of today’s distribution networks into smart grids. Smart Meters with Smart Meter Gateways (iMSys) and Controllable Local Systems (CLS) are the essential new bricks of the future smart grid. In Germany the new law "Digitalization of the Energiewende"[2] sets up the rules for network operators to establish this secure energy information system based on the smart meter infrastructure.During the last two years the authors developed and demonstrated on laboratory and field level such a secure energy information system. The main innovation of the project is the direct and secure communication with decentralized energy systems such as photovoltaic inverters, battery storage systems, E-mobility charging stations or power to heat applications within this new smart meter infrastructure, which has been defined by technical rules from the German regulator for data security (BSI) [3]. The two-way communication is able to read measurement values from the field as well as change set points or activate curtailment of decentralized energy systems (see figure 1).

Increasing distributed photovoltaic (PV) systems can lead to voltage violations and overloading of grid assets in distribution grids. This raises the necessity to consider the future growth of installed PV capacity for the planning process of distribution system operators (DSOs). This paper proposes the combination of a solar roof potential analysis and grid integration studies at the medium voltage (MV) level based on detailed input at low voltage level. Three different methods were developed to define the distribution of PV along the feeders based on the solar roof potential, and subsequently to estimate the PV hosting capacity of these feeders. The results show that the approach with an even distribution of PV systems along the feeders leads to higher hosting capacity of PV for the analyzed grids. In addition, for most analyzed feeders in this study, an overloading of MV/LV (low voltage) transformers is expected to be the limitation of hosting capacity for potential PV systems.