Project Results

After IRENE’s two and a half years project phase the following results can be summarized:

Controllable tap changer distribution transformers
A controllable transformer (German: RONT) has been put into operation . The analysis during operation shows that the RONT is a feasible means to comply with the allowable voltage limit range even with a high share of distributed generation . The mutual influence of controllable distribution transformers is currently still under investigation. For this purpose, a second RONT was installed in the grid.

Flexible inverter
Using communication interfaces, by means of Personal Energy Agents (PEA) various grid resources can be controlled. Selected photovoltaic inverter, integrated through PEA,supported the voltage control. First experiences show that this actuators can be of great help for voltage quality. The control scheme used can respond flexibly to the respective grid situation. Thereby, the grid is less burdened in comparison with a fixed setting of the parameters. In particular, the resulting reactive power demand is reduced compared to a control with fixed cos φ, or with a reactive power supply, determining the reactive power demand by a fixed characteristic using the locally measured voltages .

Battery storage
A stationary battery storage (Li -Ion technology , 300 kW , 150 kWh capacity) was commissioned and integrated into the higher-level control system . It is to show interesting ways to use the battery storage to improve the voltage quality. There are further tests and analyzes ongoing.

Potential of grid-controlled strategies for biogas and CHP
To analyze the potential of the grid-controlled operation, an area dominating biogas plant participated in the study of direct marketing. The usage of biogas plants and cogeneration plants with combined heat and power has great potential to relieve networks. However, substantial improvements in plant automation and the availability of heat or gas storage are still needed.

Electric vehicles‘ impact on distribution grids
Based on data from the study "Mobility in Germany ", a model was developed to determine and evaluate the impact of electric vehicles on the distribution grids. In particular, analyzes are possible to know „where and when“ the grid needs to maintain reserves for charging of electric vehicles. The transferability of that model to the Allgäu region has been validated by the driving behavior of the so called „power pioneers“ (the people that supported the researches by using an electric vehicle).

Flexible charging of electric vehicles
The practicability of the grid supporting charge control has been studied. Here, a self-organizing energy automation system (SO EASY) was used, whose market- based algorithms can be used flexibly . It is shown that loading a fleet of vehicles in a rural grid bears less challenges for the grid even in a scenario replicated for 2020 (1 million electric vehicles in Germany) , as would have suspected to be . However, attention should be placed on the stress on grid, caused by the chargers’ possibly imprinted harmonics.

New calculation method for distribution networks
For extended analysis of distribution grids , RWTH Aachen University has implemented a new (three-phase) calculation method for distribution grids. This method supports Siemens in the detailed modeling of low voltage systems. Thus, the future impact of distributed generators such as PV or latest consumers as electric vehicles can be assed better. The aim is to answer the question of which technical functionality is required to be provided by the economically optimized measurement and control system.