The future has come: the 100% RES driven power system is reality

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The future has come:  the 100% RES driven power system is reality


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        <identifier identifierType="DOI">10.23723/1301:2016-5/17783</identifier><creators><creator><creatorName>Antje Orths</creatorName></creator><creator><creatorName>Peter Børre Eriksen</creatorName></creator></creators><titles>
            <title>The future has come:  the 100% RES driven power system is reality</title></titles>
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	    <date dateType="Created">Wed 21 Dec 2016</date>
	    <date dateType="Updated">Thu 26 Jan 2017</date>
            <date dateType="Submitted">Sat 24 Feb 2018</date>
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84 REE N°5/2016 ENJEUX D’UN DÉVELOPPEMENT MASSIF DES EnR DANS LE SYSTÈME ÉLECTRIQUE EUROPÉEN DU FUTUR DOSSIER 1 Danish political targets, current status and system challenges The Danish political energy and climate targets fixed in the RES (Renewable Energy Sources) directive require Denmark to reach a 30 % RES share of its total energy consumption in 2020. Besides, Danish national tar- gets aim at windpower production to correspond to 50 % of domestic gross electricity consumption (status in 2015: 42 %). For 2050, the political target is to be free of fossil fuels in the whole ener- gy sector – i.e. including transportation. The major part of variable RES in Denmark is wind energy, the remai- ning power consumption mainly based on biomass, gas and coal fired central power stations and local CHP plants. Some key figures: at the end of 2015, 5,076 MW wind power capacity and 783 MW of solar power capacity were installed in Denmark, with Danish peak load at ~ 6.400 MW and the total elec- tricity consumption at 33.6 TWh. Wind power is split into 3,805 MW onshore and 1.272 MW offshore installations. In 2015, wind power produced 14.1 TWh electricity (9.3 TWh onshore, 4.8 TWh offshore), which made a ~42 % share of the Danish electricity consumption, while solar power produced 0.6 TWh. The high RES level is already today challenging the system e.g. concerning the need for flexibility on the one hand, or by pushing power plants delivering important system services out of the market on the other hand. To fulfill the political ambitions, new arrangements concerning the technical and market design incentivizing flexibility or ancillary services, such as frequency control and voltage control, are needed and current- ly under development. This article gives examples and illustrates the urgency by showing a real dispatch in a windy week. Covering flexibility needs An analysis of the future Danish energy system [1] concluded that wind power will increase by 1.5 to 3 times today’s level until 2035 (figure 1). The detailed analysis of energy use consi- dered all sectors, including heat, trans- port and industry until 2050. The use of electricity (mainly produced by wind, solar and geothermal) is expected to increase until 2035 while the use of natural gas is expected to decrease to about a third of the current level during the same period. Flexibility needs for that future have been investigated, analysing the residual load for different time periods applying 10 years of time series for Denmark and the neighbouring countries’ production and demand [1]. Results showed that flexible demand and vehicle-to-grid provide very useful service in periods shorter than five hours, but that for pe- riods lasting longer than 12 hours, other means, like e.g. exchange with neigh- bours (e.g. Norway or Great Britain) plays an important role, as they might have spare capacity when Denmark is under pressure (figure 2). Thus, especially for short term pe- riods, the market has to ensure the avai- lability of flexibility, i.e. flexibility needs, to get a price reflecting the needs. In this context, demand side management and vehicle-to-grid solutions might be options. Already some years ago, negative prices have been introduced to the day ahead spot markets, in order to release the system during hours of surplus energy. This is also influencing operation of RES, e.g. the latest installed offshore wind farm, which in case of negative spot prices does not receive any compensa- tion. Instead, the owner must pay the The future has come: the 100% RES driven power system is reality Par Antje Orths and Peter Børre Eriksen, Fredericia, Denmark Le Danemark est le pays ayant le plus important taux de production d’électricité d’origines renouve- lables variables au monde. En 2015, la production éolienne a satisfait environ 42 % de la consom- mation d’électricité du pays. Des défis liés à la flexibilité du système et à la fourniture des services système sont actuellement observés avec des développements récents pour leur faire face. Le système s’est doté de compensa- teurs synchrones et d’une nouvelle ligne HVDC VSC avec la Norvège, avec des fonctions avancées de réglage de tension et de fréquence. Des renforcements des réseaux nationaux ont été opérés. En septembre 2015, pour la première fois le système danois a fonctionné sans aucun groupe synchrone. La stabilité du système a été assurée par la liaison HVDC/VSC DC avec la Norvège et par six compensateurs synchrones. La couverture des réserves a été garantie par des centrales de production combinée et les importations depuis la Norvège. ABSTRACT REE N°5/2016 85 The future has come: the 100% RES driven power system is reality negative spot price for producing, or stop electricity production. Additionally, mar- ket rules allow since November 2011 also for on- and offshore wind power plants to participate in the regulating power market, both for up- and downward regu- lation. Today, usually, wind bids of up to ~700 MW are offered to this market. Preparing for a RES based power system, another element of the Danish TSO’s strategy is to prepare the system by means of technology, i.e. to build a high degree of necessary system support (voltage and frequency services, etc.) into the grid, thereby avoiding must run units for securing the system stability. Recent developments following this strategy have been established (figure 3): - nous compensators (2010-12); (2013-14); Figure 1: Possible Danish energy transition process: production and consumption development for different sectors – Source: Figure 2: Maximum need for residual electricity production referring to different time periods - Positive: electricity consumption - Negative: wind, PV power and interruptible consumption - Black line: resulting capacity need – Source: Figure 3: Layout of present Danish transmission system including recent developments. Source: 86 REE N°5/2016 ENJEUX D’UN DÉVELOPPEMENT MASSIF DES EnR DANS LE SYSTÈME ÉLECTRIQUE EUROPÉEN DU FUTUR DOSSIER 1 - nector to Norway with advanced sys- tem support capabilities (voltage and frequency) (2014); - sion line in western Denmark. - tions to the Netherlands and to Germany are currently under construction. Operation without central Power plants September 2nd, 2015 was a historical day in Denmark. For the first time, the system was operated without dispatching primary central power stations (figure 4). System stability was ensured by the - tion to Norway and the operation of six synchronous compensators (figure 3). The reserves were procured from local plants (small scale CHPs) and from The resulting dispatch of the Danish system during this September 2015 week was characterized by high va- riability in generation and exchange with neighbouring countries (Norway, Sweden and Germany), with an average of the Danish consumption (figure 4). On the historic Wednesday, September 2nd, wind in some hours covered the whole Danish consumption, which is not unusual, but the system was operated withoutcentralunitsinoperation.Likewise, during the very windy weekend, energy was exported to neighbouring countries. In contrast, on Monday, consumption was covered by import and generation of primary plants and to some extent local plants, as no wind was blowing. As it might be expected, the spot price showed high variations over the week with high prices during low wind hours and low prices during high wind hours and even negative prices for some hours on Sunday (red line in figure 4). As the share of RES continues to increase, weeks like this will occur more often. Thus the Danish TSO Energinet. dk continues to develop and activate – in close collaboration with market par- ticipants, regional TSOs and ENTSO-E – market and technical means to ensure system security for all customers at any time. Reference [1], “Energy Concept 2030 – An analysis of concepts and develop- ment paths to sustain a competitive and strong RE-based energy system,” 2015. Figure 4: Week in September 2015 with high flexibility of generation and transmission. Source: LES AUTEURS Dr. Antje Orths is a Chief Engineer at, involved in interna- tional infrastructure development at ENTSO-E and ENTSOG, e.g. the Ten-Year-Network-Development Plans. She is convenor of ENTSO-E’s Regional Group Northern Seas and member of the IEA Task 25 – Wind Integration. Antje Orths holds a PhD in electrical engineering from the OvG.-University Magdeburg, Germa- ny, where she is adjunct professor beside her job in Denmark. She re- ceived her Dipl.-Ing. at the Technical University of Berlin. She is member - thor of numerous scientific papers. Peter Børre Eriksen is a Chief Engineer at with pre- sent responsibilities within interna- tional cooperation on transmission system development of power and natural gas infrastructure. In addi- tion Peter Eriksen has a long expe- rience as analyst and leader in the field of energy and power market analyses and wind power integration into power systems. He is a mem- ber of SDC (System Development Committee) at ENTSO-E (European network of transmission system operators for electricity) and from 2009-15 he was chair of Nordic Energy Research Top Level Initiative: Large Scale Wind Power. Peter holds a master degree in Engineering from the Technical University of Denmark (DTU). Peter is author of numerous technical papers.