INCREASE: some first conclusions

The use of distributed renewable energy sources (DRES) has been significantly rising the last couple of years and will continue to rise over the next years. New operational and control strategies including protection algorithms are necessary in order to maintain the ability of the system to provide the consumers with a reliable electricity supply at an acceptable power quality level.

INCREASE aims to provide a significant scientific input for this. During the first six months of the project, all the different aspects of the development of these new strategies, what to include and how to test them has been thoroughly investigated and the first conceptual basis for the work was done. INCREASE will include field trials, laboratory assessments, simulations and economic assessments. For the simulations of the control strategies a simulation platform will be set up. Three different scenarios will be assessed:
1. A single phase stand-alone scenario assumes a feeder with already installed single phase PV plant. Another end-user would like to install an additional PV plant, which cannot be connected due to high voltage rise and assymetry in the grid due to the first PV plant.
2. A three phase stand-alone scenario, where a standard three phase inverter connected to a feeder and another end-user would like to install the second one. Due to the already too high voltages the connection of this second PV plant is not possible and a centrally controlled scenario with several PV plants already connected to the grid and the whole voltage band is already occupied.
3. In a centrally controlled scenario there are several PV plants already connected to the grid and the whole voltage band is already occupied. The goal is to connect and centrally control all SPPs and to develop innovative operation scenarios and algorithms for active power control of such a system.
In all the test cases a three-phase inverter is being used to find appropriate solutions depending on the scenario for voltage control, voltage unbalance mitigation, current congestion management, reactive power control to DSO, and communication.

The hierarchical control strategies comprise a local control strategy and a mutli-agent control strategy. The local control strategy mitigates voltage unbalance and under/overvoltages by means of a droop control, and provides fault-ride through capabilities. The local control strategy works without communication and thus ensures a reliable distribution grid. The multi-agent control strategy provides set-points for the droop constant and the exchanged power, and uses communication.

Apart from that approaches to provide Ancillary Services from DRES will be elaborated and an adaption of the regulatory frameworks will be proposed.

More detailed information will be available when the project progresses.