Coordinated control of decentralised grids
With an increasing electricity supply from renewable energy sources feeding into the existing grid, new responsibilities arise for the distribution grids in particular. Most distributed plants supply the low and medium voltage grid levels. With conventional operation modes and equipment, safe operation is possible only by building new lines at great expense.
In a fully developed grid, the additional capacity would only be used for a few hours per year - for example, when feed-in from photovoltaic systems is maximal due to bright sunshine, and when the wind is strong. Aim of the Grid Commander project: to keep expansion costs low. The customary quality of supply should be maintained, and priority should be given to renewably generated energy being downregulated as little as possible.
The research focus areas of Grid Commander at a glance
- Improving grid stability - The project partners aim to improve grid stability in the medium and low voltage grid levels, and have set themselves the aim of adapting these voltage levels to the new challenges. That would succeed, for example, by decentralising grid state identification in partly autonomous control systems in substations. This can help protect operational equipment and the grid control centre.
- Holistic grid state identification and forecasting - As part of overall grid state identification, the researchers are developing an algorithm to predict the state of medium voltage grids. It can inform grid operators on free capacity or bottlenecks in their grids. This can give rise to new opportunities to participate in so-called flexibility markets. In addition, the control algorithm brings about the right conditions to control grids with a certain measure of foresight.
- Decentralised control across several voltage levels - Part of the project is establishing a common means of control of medium and low voltage grids. With the finished control algorithm, it ought to be possible to measure and control the actual utilisation of the medium-voltage grid capacity in order to derive an optimal expansion strategy for the grid infrastructure, and to permit smart feed-in.
Monitor voltage and keep it within limits
The concept of Grid Commander (see above) demands that distribution grid automation systems installed in secondary substations monitor the respective low-voltage grids to prevent undue overload situations and voltage range violations. They also communicate cyclically with the control unit of the medium-voltage grid, which is located in the medium-voltage part of the higher-level 110 kV / MV substation. From there, they monitor the medium voltage grid and prevent impermissible overload situations and voltage range violations. For this purpose, it uses both the information provided by the low-voltage control units as well as other voltage and electricity information from the medium-voltage grid or the 110 kV / MV substation.
Intensive analyses are being carried out for the developed distribution grid automation system as part of specially developed laboratory and field tests. The system is being exposed to extreme scenarios and subjected to stress tests in the Smart Grid Laboratory. A field trial with a regional distribution grid operator will enable the first practice-oriented demonstration of the Grid Commander project under real conditions.
The tasks of the project partners in detail
The University of Wuppertal is largely responsible for the development of algorithms and strategies for holistic state identification and a cross-voltage level control scheme for medium and low-voltage grids.
Bilfinger Mauell GmbH are implementing the programmed procedures, including the selection and integration of suitable hardware components.
SAG GmbH are preparing the data and organise the information flow in combination with system integration.
08/2015 – 07/2018
Bergische Universität Wuppertal - Fakultät für Elektrotechnik, Informationstechnik und Medientechnik