Operating Strategies for Battery Storage Systems in Low-Voltage Grids to Limit the Feed-In Power of Solar Power Systems Using Fuzzy Control

Germany’s energy turnaround is leading to an increasing integration of photovoltaics (PVs) throughout its distribution grid. To ensure safe grid operation in times of high solar radiation, PV plants must either be throttled back to comply with the feed-in limitation or store a portion of their excess electricity in batteries. This paper presents a grid-optimized operating strategy for PV storage systems based on a Fuzzy Logic Controller that reduces peak feed-in and thus also PV curtailment losses. The Fuzzy Logic Controller uses data on PV power surplus and battery charge level as input variables. To obtain good results, the set of numerical parameters of the membership functions is enhanced by evolutionary programming.The energetic assessment shows that even small electrical storage capacities (<<5?kWh) reduce curtailment losses considerably when using the grid-optimized operating strategy. The economic assessment shows that, in 2016, investments in PV storage systems with large PV plants and small batteries have small (positive) Internal Rates of Return. The system efficiency of the battery storage has a small impact on the profitability of PV storage systems, whereas the cycle stability and the electricity purchase price have a large impact. Moreover, there is an economic benefit for plant operators to switch from the simple to the grid-optimized operating strategy. Solar forecast inaccuracies and variations in load and generation profiles have a negligible impact on the performance of the control algorithm.     

Negative Strompreise und der Vorrang Erneuerbarer Energien

With the appearance of negative prices a discussion about flaws in the design of the German electricity market arose. We show that negative prices are not only due to the integration of electricity from renewable energy sources. Negative prices can actually increase welfare. Yet, a loss of welfare does arise because of the priority feed-in of these sources. They are inclined to deliver energy even when the cost of production exceeds the market price, i.e. the electricity’s value. We suggest to remove the priority feed-in combined with a modification of the feed-in tariffs. Thereby, renewable electricity producers will suffer no drawbacks but social welfare increases.     

Diffusion der Biogastechnologie in der Schweiz: eine GIS-basierte Multiagenten-Simulation

In this article we introduce a GIS-based multi-agent simulation model. It is used to study the spatial diffusion dynamics of agricultural biogas plants in Switzerland, which lags markedly behind those in the neighboring countries Austria and Germany. The investigation concentrates in particular on the impacts of economic factors and of locally available resources on the diffusion process. The model considers three different types of plants (100 kW_el, 200 kW_el, 1 MW_el). The results show that feed-in tariffs, cosubstrate prices and the revenues from heat sales are critical parameters. They indicate further that the present promotion policy fosters smaller plants, whereas larger plants are preferred only in few areas with high substrate densities. Finally, we find evidence that increased heat sales can significantly raise diffusion dynamics, and that the higher feed-in tariffs planned in Switzerland could actually overcompensate deteriorating cosubstrate prices.     

Procuring Flexibility to Support Germany’s Renewables: Policy Options

To continue balancing supply and demand for power is a growing challenge on Germany’s path to producing 80?% of its electricity from renewable sources by 2050. Large-scale investment into a range of technologies will be required to provide the flexibility necessary for balancing. This paper introduces a simple analytical framework to evaluate the German legislator’s numerous efforts to address this challenge. It then proceeds to make two proposals as to how flexibility can be sourced more cheaply. Priority should be given to measures that enable the existing power markets to generate stronger rewards for flexibility. We thus call for financial incentives for variable electricity tariffs to elicit more consumer response and for investment subsidies instead of feed-in tariffs for more demand-oriented renewable power generation. If additional explicit incentives for flexibility are necessary, they can be provided through a market for flexibility.     

Gleichzeitigkeit als Leistungsgröße: Inter- und Intra-Klassen-Leistung volatiler EE-Einspeiser

The energy transition focuses on the expansion and enhancement of distribution grids and the integration of decentralized renewable generation plants. The integration of decentralized plants presents a major challenge for distribution system operators in particular. The planning and dimensioning of energy grids requires knowledge of all integrated generating units and power consumers, as well as their power ratings. Furthermore, knowledge about the diversity of renewable power plant types enables distribution system operators and scientists to selectively or cumulatively assess the maximum feed-in capacity. This is particularly important for the assessment of case studies or border scenarios. The purpose of this article is the evaluation of the maximum simultaneous feed-in power of PV and wind power plants. Furthermore, the ratio of the installed power to the maximum power generated by renewable power plants is also investigated. The diversity factor describes the ratio of the sum of all individual load’s maximum powers to the number of loads. This simultaneity can also be adapted to renewable power plants. However, it is differentiated here between simultaneous power within one renewable power plant type (intra-class performance) and simultaneous power of different renewable power plant types (inter-class performance). In cooperation with one of the largest national distribution network operator, regression lines are approximated by statistical analyzes, in order to determinate the diversity of the Central German area.     

Die Auswirkungen des EEG auf das Energiesystem Deutschlands – Eine Betrachtung mit dem Energiesystemmodell TIMES-D

In Germany, the electricity generation from renewable energy has been promoted since the year 2000 by a feed-in tariff system, the Renewable Energy Sources Act (EEG). This article evaluates the long-term impact of the German feed-in tariffs on the development of the German energy system with the help of the energy system model TIMES-D. In the model-based analysis, both the payment side (i.e. the tariffs) and the cost side (i.e. the EEG apportionment) are taken into consideration. Through the promotion of the feed-in tariff system—in combination with the European Emission Trading Scheme (ETS)—the use of renewable energies in electricity generation in Germany rises considerably such that renewable energy sources account for almost 40% of total gross electricity consumption in 2030. Accordingly, until 2020 total EEG fee payments as well as the EEG apportionment increase significantly. The impact of the feed-in tariff system on final electricity demand is, however, relatively small. Alternative scenario settings show that the expansion of the renewable electricity generation through the feed-in tariff system clearly exceeds the development which would occur when trying to reach the reduction targets of the ETS in a cost-efficient way.     

Vertical Contracts and Downstream Entry*

We study the implications of different contractual forms in a market with an incumbent upstream monopolist and free downstream entry. We show that traditional conclusions regarding the desirability of linear contracts radically change when entry in the downstream market is endogenous rather than exogenous. By triggering more entry than two-part tariffs, wholesale price contracts can generate higher aggregate output, consumer surplus, and welfare. In light of this, the upstream monopolist may prefer to trade with wholesale price contracts as well as to give up part of its bargaining power when it is high.     

K?nnen sich erneuerbare Energien langfristig auf wettbewerblich organisierten Stromm?rkten finanzieren?

In this paper we address the issue of whether renewable energy sources can be integrated into power markets if the use of renewable energies is extended at the desired speed. Market integration means that renewable energy sources have to cover their full costs from revenues on competitive markets. In the first part of this paper, we evaluate the long-term revenues of intermittent renewable energy sources using a high resolution power market model. Considering the renewable targets of the German lead study of 2010, we show that due to the merit order effect, intermittent renewable energy sources, such as wind power and photovoltaic, cannot be financed through power markets alone, even if their full costs fall below those of conventional power plants. This is also true for scenarios with high CO₂-prices and increasing spot market prices. In the second part of this paper, we discuss whether in the long run additional instruments such as green certificates or capacity markets would allow for a more competitive financing of renewable energy sources. Center stage in the discussion is the question under which circumstances these instruments increase competitive pricing and decentralised market decisions.     

Wettbewerbsfähigkeit der Photovoltaik im deutschen Energiemix – Neudefinition des Ansatzes der Netzparität

Photovoltaics are one of the fastest growing energy sources in the world. Despite high costs and a limited energy yield, attractive support schemes particularly the German renewable energy law have paved the way for the strong market growth of this technology within the last decade. Here the question arises as to when photovoltaics will reach a competitive level in Germany without the support of subsidies. The prominent grid parity approach is simple and considered critical in this discussion. It is critical because of the different references regarding the costs of electricity generated by a newly installed PV system and the electricity price of private households, which consists of electricity generation, distribution, sales as well as taxes and duties on the one hand. On the other hand, there are different time references in the calculation of electricity generation costs and electricity prices of private households. Transferring the approach of Levelized Costs of Electricity (LCOE) to all power generation plants within the energy mix means a redefinition of the grid parity of photovoltaics will be carried out. Here the electricity generation costs of photovoltaics as well as the energy mix will be calculated in the same way. The LCOE calculation refers to the whole life cycle of every power generation plant. That is why a balance between the high investment costs of photovoltaics and the increasing operation costs of fossil fuelled power plants is made. It can be shown that the reaching of competitiveness of photovoltaics in Germany depends on structural changes in electricity generation and it is to be realized within the anticipated time frame until the year 2020.     

Integration erneuerbarer Energien in die deutsche Stromversorgung im Zeitraum 2015�C2020 mit Ausblick auf 2025

The dena grid study II examines the integration of renewable energies into Germany??s electricity supply up to the year 2020 and gives a qualified outlook up to 2025. The study develops geographically differentiated scenarios for installed wind power capacity, on the basis of which time series of the wind power feed-in into high and extra high voltage nodes and offshore wind farms are generated. Future requirements for the transmission grid and grid extension options are analysed. Opportunities to introduce more flexibility in the power system in terms of supply and demand are examined. The study gives a conceptual perspective of the need for grid extension in inner Germany in order to fully integrate renewable energies, whilst operating power stations at optimum cost and exchanging electricity with other countries in response to market demands within the scope of the specified transmission capacities.     

Price Sensitivity of Hourly Day-ahead and Quarter-hourly Intraday Auctions in Germany

The introduction of the quarter-hourly intraday auction in 2014 for the German market confirms a tendency towards short-term energy markets. The reason for the new market was the need to trade shorter periods than just hours a day-ahead to minimize open positions in the more volatile continuous intraday trading. The increased production capacity of solar power boosted this requirement for new short-term power products. The quarter-hourly market shows a distinctive zigzag price formation. We identify two influencing factors: first, the solar residual that combines the trading of solar power ramps around midday as well as the gradients of consumption and thermal power plant ramps throughout the course of the day, and second, a characteristic two stage market design with higher liquidity for the hourly than for the quarter-hourly auction. Therefore, demand, solar generation and inflexible ramps of thermal power plants are hedged at the hourly day-ahead auction and use the quarter-hourly auction only to balance the remaining differences. To prove this argument the price sensitivities of the hourly day-ahead and quarter-hourly intraday auctions in Germany are compared based on actual bid and ask curves from 2015 and 2016. Finally, the development of an adequate design of future spot markets is discussed.     

Can evidence of pricing power help market power assessment? Broadband Internet in Ireland and the Netherlands

This article proposes a simple hedonic price test to assess whether firms may have pricing power. The test allows NRAs to compare prices of providers of differentiated products on a like-for-like basis. Testing for pricing power could be a useful complement to market share analysis. This is especially the case in market reviews periodically undertaken by European communications regulators. As an illustration the test was applied to broadband Internet access services in Ireland and the Netherlands. Results appear encouraging as they are broadly aligned to the decisions of the regulatory authorities in both countries that the incumbent DSL operators had market power at the time.     

Wie viel Europa braucht die Energiewende?

It is often argued that Germany’s energy transition (the so-called “Energiewende”) needs to be “Europeanized”, so as to make the transition process more efficient. In particular, the German system of feed-in tariffs for renewables is criticized for being an obstacle to efficient European energy supply. However, we point out that Germany’s approach is no outlier but rather well embedded in the European context of heterogeneous energy policies. Also, full centralization and harmonization of political decisions on the EU-level may not be desirable in many fields of energy policy beyond climate protection if the full economic costs of energy supply are taken into account. In addition, legal and politico-economic constraints need to be considered. Against this background, we identify priorities for fostering the European dimension of the Member States’ energy policies, such as the coordination of grid extensions and capacity markets.     

Elektroautos in einer von erneuerbaren Energien geprägten Energiewirtschaft

The German Federal Government wants to establish Germany as a leading market for electric mobility. Potential environmental benefits and changes in the economic framework conditions of the energy sector are described in this paper. In order to quantify the electricity split which is actually used for charging electric vehicles, two economic models for the energy sector, a model for the market penetration of electric vehicles, a vehicle model and an LCA model are brought together. Based on an assumed dynamic increase of electric vehicles to 12 million in 2030, an additional electricity demand of about 18 TWh is calculated. If the vehicles are charged directly after their last daily trip, the peak load increases by 12%—despite the small increase in electricity demand. First model calculations for the development of the European power generation system show that the direct impact on the construction of new power plants remains low even until 2030. An impact of electric mobility on CO₂ certificate prices can only be seen from 2025 onwards and is limited to an increase in certificate prices by a maximum of 8 % in 2030. An optimisation is possible with intelligent charging strategies: The peak load without demand side management can be reduced by 5 GW and about 600 GWh of additional wind energy can used which would otherwise have been throttled due to feed-in management—about 3.5 % of the total electricity demand of electric vehicles. On the other hand, demand side management leads to more coal power plants instead of gas power plants being used to meet the additional electricity demand. If additional renewable sources are installed along with demand side management, the electricity for electric vehicles is almost carbon free. This is also reflected in the life cycle balance of electric vehicles which also includes vehicle and battery production: With today’s average electricity split in Germany, the greenhouse gas emissions of electric vehicles are about comparable to vehicles with conventional combustion engines. However, the electricity split in 2030 or the use of additional renewable energy sources lead to a significant advantage in the greenhouse gas balance.     

Multi-Criteria Analysis of Grid Expansion Concepts on the Low Voltage Level

In recent years, the power generation and consumption in Germany have undergone fundamental changes. New political regulations and the renewable energy law have resulted in a sharp increase in the installed generation capacities of photovoltaics connected to a low voltage grid. Distribution system operators are faced with the challenge of preventing grid component overload as well as a violation of voltage range. Due to increasing requirements of grid expansion in future years, distribution system operators must evaluate new expansion concepts compared to conventional ones. One interesting approach is the installation of Voltage Regulated Distribution Transformers (VRDT) regulating the voltage level of distribution grids. In this paper, the local network of one of the largest German distribution system operators is analysed in the context of future requirements for grid expansion using the conventional and VRDT expansion. Grid structures have grown over the last decades and therefore vary widely in their grid topologies. A classification of the entire grid in a few classes results in high inaccuracies. Therefore, the creation of synthetic grid structures is developed for the calculation of the required network extension. In addition, both grid expansion concepts are evaluated not only for financial aspects, but against environmental, economic, technological, and social dimensions using a multi-criteria decision making approach. The study shows a high market potential for VRDTs in low voltage grids with an increasing enforcement level of photovoltaics.     

Opening up for competitive advantage – How Deutsche Telekom creates an open innovation ecosystem

When, on 21st September 2006, ' The Economist ' compared incumbent telecommunication operators with dinosaurs that could soon face extinction, most readers were ready to agree. The mixture of declining revenues and fierce competition was believed to shake the market and soon to dethrone former national champions. However, there are ways to fight that extinction and one way is to open up for competitive advantage. This paper reflects on a case study at Deutsche Telekom, the German national telecommunication operator. The aim of this study is to analyse to what extent the open innovation paradigm has been embraced inside this now multinational company. Using empirical evidence from 15 in-depth interviews, we identify 11 open innovation instruments and detail their value contribution. We can show that Deutsche Telekom has successfully enhanced its innovation capacity by opening up its traditional development process and embracing external creativity and knowledge resources.     

The response strategies of incumbent mobile network operators on the disruptive potential of public W-LAN in Germany

This paper examines how three incumbent mobile network operators (MNOs) in Germany responded in terms of their strategy to the emergence of the wireless local area network (W-LAN) technology and how they interpreted this potentially disruptive technology in their own strategic context. Additionally, prior empirical results and forecasts on the limited disruptive potential of W-LAN for the German MNOs lacked persuasive firm-level evidence to distinguish the real reason for the presented observations and analysis. So far it was unclear whether the observations were caused by successful response strategies of incumbent MNOs or by the inherent limited disruptive potential of the W-LAN technology. For this purpose case studies of three major MNOs in Germany were performed to assess and compare their respective response strategies. Using the theoretical framework of disruptive technology, the results were evaluated in a cross-case analysis to study how these firms interpreted and reacted to the potential disruptiveness of W-LAN. The results indicate significant differences for the respective MNOs between their perception of W-LAN as a potential disruptive technology, their strategic development processes inside the organisation to understand the potential impact of W-LAN on their respective business model, and to enforce an appropriate response strategy and structural implementation. This incumbent heterogeneity depends primarily on their idiosyncratic strategic and structural context. These findings reveal that the incumbent MNOs in Germany were aware of the disruptive technology concept but did not react in a theory-conform way. However, since W-LAN had a sustaining impact on the MNOs and their response strategies followed sustaining reaction patterns, earlier studies, which show a limited disruptive potential of W-LAN for the German MNOs, are supported.     

Mögliche Entwicklung der Umlage zur Förderung der Stromerzeugung aus erneuerbaren Energien durch das Erneuerbare-Energien-Gesetz bis 2018

As a result of the strong growth of renewable energies in the German electricity sector within the last few years, the allocation of renewable costs to the consumer (RES-E apportionment) has been set to 5.277 ct/kWh for 2013 (ÜNB, Pressemitteilung der Übertragungsnetzbetreiber zur veröffentlichten EEG-Umlage 2013, 2012a). This article presents potential developments in the costs of promoting renewable energy and the RES-E apportionment in Germany using three different scenarios. Each of the scenarios considers different trends with respect to further deployment of renewable energies, wholesale prices and electricity demand. Due to the underlying uncertainties surrounding these major parameters, the scenarios show a wide range for the RES-E apportionment. A reduction of the RES-E apportionment can be reached if we consider an increase in wholesale prices. However, the scenarios indicate a further increase in the RES-E apportionment, where the amount heavily depends on the further deployment of renewable energies and the development of wholesale prices. Despite the reduction of feed-in tariffs, a main contributor to an increase in the RES-E apportionment is still the ongoing deployment of photovoltaics (PV). In order to prevent a further cost increase without inhibiting renewable targets, it may be worth focusing on comparably cheaper technologies in the further deployment of renewable energies.     

State of the German Short-Term Power Market

The paper at hand provides a comprehensive overview of the current state of the German short-term power market with focus on trading and efficiency. The pivotal question is whether current market designs are appropriate to maximise social welfare. If this can’t be confirmed, trade-offs between technical restrictions, transparency requirements, the structure of the supply side and regulators focusing mainly on consumer surplus are analysed, which prevent markets from being fully efficient. The emphasis is on Germany due to it’s central location in Europe, it’s sheer size and the rapid increase of renewable generation in recent years. This development forced the German power market into a state of transition. As a result, developments in Germany might serve as a blueprint for other European countries. The introduction of negative day-ahead prices, the implementation of a very liquid intraday trading, a quarter hourly auction and market-based systems for the procurement of Ancillary Services are just some examples of Germany’s pioneering role. On the other hand, negative effects of the rapid changes such as the excessive use of non-market based redispatch measures and system endangering imbalance price regimes shall also be explored. As a matter of course, cross-references to other European countries and harmonisation projects are included as the German market is well interconnected with neighbouring markets.     

Prognose der Day-Ahead Wind- und Photovoltaikstromerzeugung – Einflussgrößen und Zuverlässigkeit

In the future, the percentage of renewable energies in the electricity generation is expected to increase continuously. Especially weather-dependent wind and solar power plays a substantial role. These energy sources are partly characterized by a fluctuating and imprecisely predictable power generation. To cover the residual load and to balance the forecast errors a rising number of flexible producers and consumers will be needed in the future. This is necessary to ensure the high security of supply of the German electricity grid.Against this background, the objective of the following investigation is to analyse the day-ahead forecasting quality of the feed-in from wind and photovoltaic systems in the control areas of Germany’s transmission system operators and in the entire area of Germany for the years 2010 to 15. The aim of this analysis is to identify the crucial parameters that influence the forecast error. Subsequently, the share of the wind and photovoltaic power forecast which can be considered as reliably predictable for the following day is estimated. In addition, the increase in this reliable prediction through a higher level of detail in the assessment of the forecast error is quantified. Based on these results, the need of flexibilities through the weather-dependent electricity supply from wind and photovoltaic systems can be estimated, and the impact on the electricity system can be evaluated.