New reactive power management for distribution grids

Project state

In the course of the energy transition, distribution grid operators are facing new tasks and challenges with regard to ancillary services. One aspect is the provision of reactive power. Reactive power is generated mainly during the formation and collapse of magnetic fields. Reactive power flows in grids affect voltage stability and grid stability. Today, these undesired currents are mainly compensated by conventional power plants. Due to the gradual discontinuation of large nuclear reactors and coal-fired power stations, the system calls for alternative solutions.

The aim of the researchers of the SyNErgie project (short for “System-optimising grid and energy management for the distribution networks of the future”) is a description of grid planning and operational management strategies. They aim to create new ways of optimising the reactive power balance of distribution networks. They include, amongst others, operational compensation systems and decentralised generation plants in their planning. Particular attention is paid to the integration of a comprehensive reactive power management concept that includes control and planning strategies. Reactive power controllers are being employed in a planned field test that allow autonomous decentralised and centralised control via the grid control centre of the grid operator.

Interplay of decentralised systems and operational compensation systems

Schematic representation of a distribution network with decentralised integration of reactive power (Q) via consumers and producers, and operational compensation systems and distributed generation plants.
Schematic representation of a distribution network with decentralised integration of reactive power (Q) via consumers and producers, and operational compensation systems and distributed generation plants. Image: OTH Regensburg - FENES

Large power consumers such as industrial enterprises usually have their own compensation systems, with which they can compensate for the reactive power they cause. Previously fixed limits on the grid connection point serve as a control variable. According to current legislation, distributed generation plants such as photovoltaic systems, biomass plants and wind turbines are required to take part in maintaining static voltage stability by using reactive power. As a result, the voltage at the feed-in point increases less, which is favourable in terms of integrating the plants. Typically, the provision of reactive power takes place via inverters, but the use of compensation systems is possible as well.

At the heart of the project are two field trials in Nuremberg and Würzburg, with which the researchers aim to test the developed reactive power management system in practice. This means: industrial enterprises and generation facilities should actively provide reactive power. This should demonstrate that a significant optimisation in terms of reactive power management is indeed possible. By tapping into this existing potential in conjunction with a grid-relevant application, the project participants expect a significant optimisation of grid operation.

The project partners in detail

The project group consists of the two distribution network operators Main-Donau Netzgesellschaft mbH and Mainfranken Netze GmbH, and the two compensation system manufacturers FRAKO Kondensatoren- und Anlagenbau GmbH and KBR GmbH, as well as Ostbayerische Technische Hochschule (OTH) Regensburg. The grid operators and compensation system manufacturers are making an important contribution, such as practical experience, measurements and testing areas for the development of the models while evaluating them at the same time. OTH Regensburg is responsible for model development and alliance coordination, supported by the Regensburg Center of Energy and Resources (RCER).

Project duration

03/2015 – 02/2018


Prof. Dr.-Ing. Oliver Brückl
Project coordinator
OTH Regensburg
Seybothstr. 2
93053 Regensburg
+49 941 943-9881
+49 941 943-1424

Basic information

The energy generated in a grid must always be equal to the energy consumed. The ancillary services are tasked with ensuring this.


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