Robustness of a self-sufficient control algorithm in real grid situations in the low-voltage grid

Abstract:
The increasing volatile feed-in of distributed energy resources and the ongoing addition of new electricity consumers pose challenges for distribution system operators. In order to replace rigid technologies such as time switches, a grid-serving load management concept is being pursued. The technology used today, which controls according to fixed time schedules, no longer corresponds to the grid behavior with regard to volatile feed-in and time variable consumers. The proposed self-sufficient, decentral acting control algorithm estimates the actual local grid condition with the help of historical measurement data. In a real laboratory in Germany, about 70 control units are installed at the grid connection point of a household in the low-voltage grid. The control units handle the measurement data logging and controls the flexible loads in such a way that they support the grid in accordance with the requirements that limit the permissible blocking times per day. After the principle robustness was already proven, special grid situations are covered in these investigations. These are for example actions of on-load tap changers or changes of the grid structure due to switching operations of the distribution system operator. It is shown, that the self-adjustment of the algorithm balances these short-term changes as well as long-term seasonal effects. The decentralized algorithm estimates the local grid condition in order to calculate grid-serving switching commands. The approach requires no manual intervention and no knowledge of the processes in and on the grid. After a power failure, the system is immediately up and running again, even without communication. The decentralized approach already provides distribution system operators with a low-communication a control solution in compliance with legal and contractual requirements today.