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Photovoltaic Control and Integration

Periodic Reporting for period 1 - PVCI (Photovoltaic Control and Integration)

Période du rapport: 2017-11-01 au 2019-10-31

The sustainable development plan in the EU and the worldwide commitments against climate change dictate decarbonisation of the energy sector by integrating massive amounts of renewable energy sources. Among the various renewables, the solar photovoltaic (PV) technology has shown excellent potential for high integration in both rural and urban environment, but currently faces important limitations that do not allow “too much” solar to be incorporated into our electrical network. This is mainly because we cannot control when the sun shines (e.g. no generation during the night) and because the solar PV systems are not “grid-friendly”, i.e. they cannot assist the grid during electrical disturbances. If these technical limitations, similar to other renewables too, are not overcome we will never manage to integrate the necessary high levels of solar into the electrical network and will fail our decarbonisation targets.

The PVCI project aims to investigate these technical challenges and come up with control methods to transform the PV parks into more “grid-friendly” power stations that will allow much higher deployment levels into the power system. More specifically, a major objective of the project is to develop smart control strategies for the solar park towards provision of “ancillary services” to the network, i.e. to be able to support the electric grid during faults and other disturbances. Another main goal is to develop the proper modelling framework to study complicated “dynamic phenomena” related to the operation of PV systems, so as to assess how much solar we can deploy.

The results of this project serve as a useful tool and guide to increase the amount of solar integrated into our power system, contributing to our sustainable targets and the leader position EU holds in the PV industry.
The first major objective is to investigate how we can make the solar photovoltaic (PV) systems more “grid-friendly”. To this end, a control method was developed that allows a PV system to keep “power reserves”, i.e. to keep some backup power, and be able to release this energy to support the electric grid during the “difficult times”, i.e. at disturbances such as loss of generation, disconnection of large load etc. This new feature renders a solar PV park much more compatible to the power system, without having to install costly batteries, thus paving the way for higher solar integration into the electric grid. This research was experimentally validated on an actual PV system and the results were published in 2 papers.

The second main scientific objective is to come up with the framework to assess how solar PV systems behave at dynamic phenomena, i.e. fast changes in the electric grid. Complete dynamic models were developed to perform power system studies of these dynamics, and therefore allow impact assessment of significant levels of solar integration into the electrical network. These results were disseminated via 3 publications in top journals of the field.
The carried research pushed the boundaries of the state of the art in the field of photovoltaic (PV) system control and integration. The control method developed to keep power reserves is the first in the literature to achieve this goal under “partial shading conditions”, i.e. when the solar panels are shaded by nearby objects. Since the scientific community is now eagerly looking on how to make the PV systems more “grid-friendly”, these findings are quite relevant and will serve as guidance in the years to come. In addition, the modelling framework for PV system dynamic studies captures for the first time technical details often omitted (ancillary services to the grid, unbalanced network operation etc.) and is formulated in a convenient state-space form, thus serving as a valuable tool to researchers studying the solar integration levels.

This project has investigated and suggested methods that will allow to deploy more solar into our power system, the relevant findings being relevant and useful to the scientific community and the PV industry.
Dynamic model of a PV system
Experimental setup
Keeping power reserves and estimation of the maximum power
Photovoltaic array