Why should Europeans be concerned with renewable energy?

Climate change, the consequences of which we can only imagine, is a very good reason to change our source of energy

from the present hydrocarbon fuel to an infrastructure powered by renewable, as investigations by the Intergovernmental Panel on Climate Change have shown. According to research by Aarhus University, the ideal mix of energy sources is approximately 60 per cent wind power and 40 per cent photovoltaic (PV) power. Thus, the economic potential for PV is massive.

What is your latest project, PVNET.dk, all about and how will it help renewable energy in Europe?

The project aims to show that it is possible to integrate PV power, and other renewable energy sources, into an existing grid without causing major problems. The goal is to present PV power as a natural part of the future electrical network. We hope to do this by reaching and effectively managing a grid with a level of PV penetration that is close to the European Photovoltaic Industry Association (EPIA) scenario of 12 per cent Europe-wide photovoltaic penetration by the year 2020, a figure that would produce a paradigm shift in the way PV power is perceived.

What is a smart grid and what are the advantages of using one in conjunction with photovoltaic power?

The purpose of a smart grid is to control how much energy is being consumed at any given time by establishing two-way communications with inverters. The PVNET.dk team hopes that by using smart grid technologies we can overcome the fears held by many network operators that too much PV power in the network could cause the voltage to surge, overloading the infrastructure. In a smart grid this can be avoided, for instance, through controlling local voltage by exchanging reactive power with the network.

Why choose the Island of Bornholm as the location for the PVENT.dk project?

Bornholm’s electrical infrastructure was already well-prepared for this type of integration, as it is the home of several other smart grid projects, including the EcoGrid EU and the Photovoltaic Island Bornholm Project (PVIB), the work of which we are building upon with our current PVNET.dk project. PVIB aims to install 5 to 6 MW of PV power in the grid, which would amount to around 8-12 per cent penetration across the island.

What challenges have you faced during your research?

The lack of international smart grid standards has been a major obstacle, but that is also what makes the project so cutting-edge. This project, along with many others, will act as a ‘guinea pig’ and what we learn in the course of our investigation will feed directly into the development of future standards in the field.

What has been learned from the work on Bornholm so far?

Since the implementation of the 5-6 MW photovoltaic systems as part of the PVIB project, research has mainly been focused on finding the maximum level of PV penetration that can be securely handled by the network. Indications suggest that the grid can handle 130 per cent (of the size of the local distribution transformer) before overloading problems begin to occur. Beyond that threshold, any issues can be managed by integrating the inverters into the smart grid. We are very close to establishing the necessary two-way communication with the inverters installed on Bornholm and the market virtual power point, which will allow us to control the amount of energy going in and out of the grid at any given point via a signal sent over the Internet.

How will the photovoltaic smart grid impact the lives of citizens on Bornholm?

After having installed a PV system, we have seen people become increasingly conscious of their energy consumption. This could be a product of the Danish policy of net-metering electricity consumption, as opposed to the feed-in tariff operated in many other European nations. The pairing of photovoltaics and the smart grid works well to minimise consumption – that’s what the smart grid is designed to do. The problem with diffusing smart grid technology is that there is no financial incentive for the individuals to participate – but combining it with metered photovoltaic power could change this.

Lead System Technology Engineer Dr Søren Bækhøj Kjær talks about the importance of solar power in Europe and what his current PVNET.dk project, bringing photovoltaic (PV) power to the Danish Island of Bornholm, could do to open up the possibilities of environmentally friendly energy for everyone

Solar power for the masses

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ET.Dk

Solar power gets smarthow smart grid technologies in photovoltaic power systems could make for greener, more efficient energy

BorNHolm IS aN island quite like no other. Located in the Baltic Sea, it is the testing ground for the latest developments in the application of photovoltaic (PV) power in the PVNET.dk project.

Danfoss Solar Inverters, a manufacturer of inverters specifically designed for photovoltaic systems, together with researchers from the Technical University of Denmark (DTU), have collaborated with EnergiMidt A/S, a local distribution network operator, who have been in the PV business for more than 20 years, and Østkraft, the Bornholm grid operators, to embark upon the ForskEL research programme, supported by Energinet.dk. The research, headed by Dr Søren Bækhøj kjær, aims to demonstrate that PV power can be a reliable and realistic source of energy, not simply for small communities but also on a national level.

One of the projects funded by ForskEL aims to integrate 5 MW of PV power into the Bornholm grid, which would correspond to roughly 9 per cent penetration across the island, a figure within touching distance of the European Photovoltaic Industry Association (EPIA) goal of 12 per cent penetration of PV power across Europe by 2020, a threshold it believes to be crucial in creating a paradigm shift in the way PV is perceived in the energy system. The project offers an invaluable opportunity to demonstrate the practical application of PV power and other renewable energy sources (rES) by showing that such power sources can be integrated into existing infrastructures without significant problems.

GETTING To GrIPS WITH SmarT GrIDS

A smart grid, according to the definition developed by the European Technology Platform Smart Grids, is an electricity network that “can intelligently integrate the behaviour and actions of all users connected to it – generators, consumers and those

that do both, so-called ‘prosumers’ – in order to efficiently deliver sustainable, economic and secure electricity supplies”. In other words, energy can go in and out of the grid as required. The two-way communication that a smart grid allows means that the energy producer can inform the utility grid operator of the output of the power station and the grid can then be managed accordingly. Smart grids could also allow customers who own appliances with smart grid functionalities to become not only simple end-users but directly take part in the operation of the grid, thanks to the two-way communication embedded in the network.

The challenge faced by the PVNET.dk team will be to see if the Bornholm grid will be able to accept the proposed amount of PV power (and other rES) without requiring reinforcement. Smart grid technology could help in this respect, as it could help manage energy consumption and production more efficiently, balancing the grid.

THE currENT STaTE of PHoToVolTaIc PoWEr

In Denmark, as in most of Europe, the current market for PV technology is, as yet, limited. The typical consumers of PV technology are generally middle-aged owners of residential properties or institutions or enterprises that want to emphasise their green credentials; they are not yet considered technologies suitable for the mainstream market. Despite public perception, both PV and smart grid technology are viable methods of reducing energy consumption and reliance on fossil fuels.

In 2007, the Danish Government made a commitment to reduce fossil fuel use by 15 per cent as part of its ’Visionary Energy Policy’, which for the first time specifically included photovoltaic power. By 2009, steps had already been taken to achieve their goal of increasing penetration

of renewable energy sources by 30 per cent by 2025 – 4.6 MW of PV power had been installed across Denmark (including Greenland), most of it distributed through grid systems. Presently some 120 MW have been installed in 2012, due to the net-metering support scheme applied in Denmark. The ForskEL research programme and the PVNET.dk project are further steps on the road to making these goals a concrete reality.

INTEGraTIoN

PVNET.dk will build upon the work on the Photovoltaic Island Bornholm (PVIB) project, which has to some extent prepared the infrastructure of the island for integration of a large amount of PV power. The projects propose to reach their 9 per cent penetration target by installing three main types of PV generators: photovoltaic rooftops on private houses, photovoltaic plants on municipality buildings and facilities, accompanied by one or more large-scale PV solar power plants. These three methods of generating energy will combine to form the PV Virtual Power Plant (VPP) on Bornholm.

The integration of PV power will be executed to the team’s three step plan: first, the theoretical stage, where the existing electricity grid will be tested and after one and half years, the researchers will report back with solutions as to how the grid can be prepared for the planned integration. Step two involves the implementation of these solutions and step three is essentially a year-long, in-the-field assessment of how the network is operating both with and without the modifications proposed by the PVNET.dk team to get an objective picture of their impact.

oVErcomING cHallENGES

The plan is deceptively simple – but the project must overcome some significant obstacles if it is

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INTEllIGENcE

PVNET.dkaPPlIcaTIoN of SmarT GrID IN PHoToVolTaIc PoWEr SySTEmS

oBJEcTIVES

The PVNET.dk project is exploring ways to integrate large amounts of photovoltaic power generation into the low-voltage distribution network, without having to reinforce the network. This is done by developing and applying smart grid technologies and other ancillary services. The developed solutions are to be rolled out on the island of Bornholm.

ParTNErS

Technical university of Denmark (DTU)

Østkraft Net

Energimidt

Danfoss Solar Inverters

KEy collaBoraTorS

Jacob Østergaard • Guang Ya Yang • Majken Rolsted Mattesen • Carl Stephansen • Adrian Constantin • Radu Dan Lazar • Hans Peter Ballegaard • Søren Bækhøj Kjær • Hans Henrik Ipsen • Thomas Henrik Pedersen • Henning Laursen

fuNDING

PVNET.dk is partly funded by the ForskEl research programme, administrated by Energinet.dk

coNTacT

Dr Søren Bækhøj Kjær MSc, PhD

Danfoss Solar Inverters A/S Jyllandsgade 28, Dk-6400 Sønderborg Denmark

T +45 7488 1359 E sbk@danfoss.com

http://pvnet.dk

SØrEN BæKHØJ KJær received MSc and PhD degrees in Electrical Engineering from Aalborg University in 2000 and 2005, respectively. he is currently with Danfoss Solar Inverters, where he holds a position as Lead System Technology Engineer. his main interests are switching inverters for photovoltaic applications, large-scale grid integration, and smart grid.

to prove that using a smart grid to distribute PV power is reliable, safe and efficient. For the experiment to be feasible, the Bornholm infrastructure must accommodate the large number of PV installations involved in testing the functionality of the smart grid and its ancillary services. Even if the island proves to be a suitable testing ground, the danger of working with nascent technologies is that some may not yet be ready for implementation.

To prove that the kind of PV integration proposed by PVNET.dk is a practical method of operating a large grid system, it is essential to show that the network can cope when things go wrong. Providing effective ancillary services will be key in making the integration process run smoothly and helping the utility company manage the grid.

For example, the PV power plant inverters must be capable of supporting the grid if voltage drops completely – each country has national guidelines on how long a plant must be able to support the network in case of a drastic voltage drop. Fortunately, it is hypothesised that in the case of a complete breakdown on the grid, a PV power plant could help black-start a grid, meaning it could independently produce enough power to restart other plants, thereby restoring the network. however, this idea requires further long-term investigation and dedicated investment in PV inverters, which are used by power plants to control voltage.

ExcITING DEVEloPmENTS

From an economic perspective, the project has plenty to offer its stakeholders and may have wider implications for the renewable energy sector. Danfoss Solar Inverters finds itself in a position to roll out technology that proves successful in this project through their PV inverter programme, bringing this technology

into the commercial arena. The project is clearly an invaluable r&D opportunity, offering the chance to test existing inverters and develop new functionalities to provide better support for grid operators and push development in the field. The smart grid technology itself provides an opportunity for grid operators to benefit from its two-way communication system and manage their grids more efficiently, within flexible parameters, reducing energy consumption.

Most crucially, if the team’s efforts were to prove successful, it would be a major step towards showing that integration of renewable energy sources into established power infrastructures is a feasible prospect – and if the EPIA target of 12 per cent photovoltaic penetration Europe-wide by 2020, then Denmark would undoubtedly be affected by this paradigm shift. Projects such as this could help the nation make such a transition and push it to the cutting-edge of energy innovation.

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OVErVIEW OF ThE BOrNhOLM ENErGy SySTEM, INCLUDING ThE 60 kV CABLE TO SOUThErN SWEDEN