Langen, Germany
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Ackermann T.,Energynautics GmbH | Ellis A.,Sandia National Laboratories | Fortmann J.,RE Power Systems SE | Matevosyan J.,Electric Reliability Council of Texas | And 7 more authors.
IEEE Power and Energy Magazine | Year: 2013

Grid codes (GCs) and dynamic wind turbine (WT) models are key tools to allow increasing renewable energy penetration without challenging security of supply. In this article, the state of the art and the further development of both tools are discussed, focusing on the European and North American experiences. © 2003-2012 IEEE.


Martensen N.,Energynautics GmbH | Kley H.,Spirae Inc. | Troster E.,Energynautics GmbH | Ackermann T.,Energynautics GmbH
VGB PowerTech | Year: 2011

There is a trend all over Europe towards power generation in the distribution network using wind, photovoltaic, and combined heat and power plants. The Danish power system can be considered a leader: already today more than 50 % of the total production capacity consists of distributed generation, mainly wind and combined heat and power plants. As a consequence of this development, it has become more difficult to predict and to control the total electricity generation. This article describes the Danish cell project, a new development for optimal management of distribution grids (cells) with large amount of distributed generation.


Martensen N.,Energynautics GmbH | Kley H.,Spirae Inc | Lund P.,Energinet.dk
CIGRE 2011 Bologna Symposium - The Electric Power System of the Future: Integrating Supergrids and Microgrids | Year: 2011

The Cell Controller is a new intelligent control system for distributed energy resources (DER) that improves security of supply-by means of emergency island operation capability-and provides a platform for TSO (Transmission System Operator) support operation and market operations. Furthermore the Cell Controller provides a SmartGrid platform for enhanced automated support of DNO (Distribution Network Operator) operations in medium voltage distribution systems characterized by large amounts of DER. The project is finishing its final testing phase in summer 2011. Grid-connected Cell Controller functions that support TSO/DNO operations and market operations were field tested in 2010 and will be tested again in 2011. Moreover, emergency island functions will be field tested in 2011 during multiple periods of operating the entire pilot Cell as an island. Among the grid-connected functions, voltage control for advanced DNO support plays a primary role, as it is designed to run in parallel with all other grid-connected functions. To perform voltage control, the Cell Controller utilizes all available distributed resources with reactive power capability in addition to substation transformer tap changers. It aims to reduce the number of tap changes required in normal operation (avoiding unnecessary wear on tap changers) while enabling steadier voltage supply for consumers and generation assets. Results obtained during the 2010 field testing confirm that the complex communication, measurement and command infrastructure in the pilot Cell and the Cell Controller algorithms perform as intended. Voltage setpoints provided through a DNO user interface to the Cell Controller are properly handed down to the assets. The Cell Controller itself ensures that the desired voltage ranges are adhered to, taking local limits for voltage and reactive power capability into account. Distributed assets with steady reactive power capability are used first, before the discrete substation transformer tap changers are employed. During the emergency island functionality, however, synchronous machines must be coordinated to preserve the reactive power balance in the islanded Cell, and voltage control must be done by the on-load tap changers alone. Simulation results already show this control scheme fully working before the final round of field tests.


Hagspiel S.,University of Cologne | Jagemann C.,University of Cologne | Lindenberger D.,University of Cologne | Brown T.,Energynautics GmbH | And 2 more authors.
Energy | Year: 2014

Electricity market models, implemented as dynamic programming problems, have been applied widely to identify possible pathways towards a cost-optimal and low carbon electricity system. However, the joint optimization of generation and transmission remains challenging, mainly due to the fact that commercial trades do not directly translate into power flows on a specific line in meshed networks. Instead, loop flows occur and potentially impact the entire transmission system. This paper presents a methodology that allows optimizing transmission investments under flow-based market coupling and complements established electricity market models implemented in a linear programming environment that are suitable for solving large-scale problems. The algorithm developed is based on a linear 'DC' representation of the physical load flow equations, expressed as power transfer distribution factors (PTDFs). It iteratively updates the PTDFs when grid infrastructures are modified due to cost-optimal extension and thus yields an optimal solution with a consistent representation of physical load flows. The method is first demonstrated on a simplified three-node model where it is found to be robust and convergent. It is then applied to the European power system in order to find its cost-optimal development under the prescription of strongly decreasing CO2 emissions until 2050. © 2014 Elsevier Ltd.


Jiang L.,Grid Energy Research Institute | Wang C.,Grid Energy Research Institute | Huang Y.,China Electric Power Research Institute | Pei Z.,National Electrical Power Dispatching and Control Center | And 4 more authors.
IEEE Power and Energy Magazine | Year: 2015

Variable generation (VG) in China is primarily wind and photovoltaic (PV) power. By the end of 2014, the cumulative installed capacity of VG in China reached 123.86 GW, accounting for 9.1% of the country?s total generation capacity. The cumulative installed capacity of wind and PV power were, 95.81 GW and 28.05 GW, respectively. The total amount of energy generated from VG in 2014 was 181 TWh (of which wind power was 156 TWh and PV power 25 TWh), accounting for 3.3% of total electricity generation. The newly installed capacity of wind and PV power in 2014 was 19.5 GW and 10.6 GW, respectively, accounting for 28% of the newly installed capacity of all generation types. Following coal-fired power and hydropower, wind has already become China?s third-largest power source both by capacity and by power generation, after nine years of high-speed growth. A rapid development of PV power generation has been experienced since 2010. The newly installed PV capacity in 2013 and 2014 reached over 10 GW for two consecutive years, accounting for about one-third of newly installed PV capacity worldwide over the same period. By capacity, PVs have become China?s fifth largest generation source after natural gas based generation. © 2003-2012 IEEE.


Brown T.,Energynautics GmbH | Cherevatskiy S.,Energynautics GmbH | Troster E.,Energynautics GmbH
European Wind Energy Conference and Exhibition, EWEC 2013 | Year: 2013

The planning and operation of high voltage direct current (HVDC) lines within synchronous alternating current (AC) transmission networks has become an important topic, particularly with the integration of remote renewables into the grid. The optimal dispatch of particular fixed AC-DC networks has already been studied in the literature; we focus in this paper on optimizing the initial positioning of the DC network within the AC network and how it should be optimally sized. The problem is challenging because the optimization criteria (such as reducing congestion, overloading and losses) are non-linear while the optimization space of possible connection points of the DC terminals is discrete. Techniques are presented here based on a linearized version of the AC load-flow equations known as power transfer distribution factors (PTDFs). Examples are calculated for Germany in the year 2030 and for the European network up to the year 2050, with renewable power plants built out to provide 90% of electrical energy.


Begluk S.,Vienna University of Technology | Troster E.,Energynautics GmbH | Schlager R.,Vienna University of Technology | Gawlik W.,Vienna University of Technology
IET Conference Publications | Year: 2013

Due to climate change and limitations of fossil energy sources, political goals that lead towards a massive increase in renewable and distributed generation, e.g. photovoltaic (PV), wind power, etc. have been proposed. However renewable generation units increase the volatility of electricity production, are only conditionally controllable and are characterized by low full load hours. These negative aspects challenge the integration of renewable energy sources into the electrical grid. Remedial measures that can be applied are the integration of hybrid energy storage in the existing energy system and the use of installed PV systems for voltage support. Hybrid energy storage balances deviations in generation and load. By providing reactive power, PV systems can limit the increased voltage level, which can be observed especially in weak grids in case of a reversed load flow due to a high power production. This paper is going to describe how to achieve a decentralized generation-load-balance by coupling the existing infrastructures (electrical, gas and thermal networks), using decentralized hybrid storage, enabling a massive integration of renewable energy sources into electrical distribution systems, as examined in the project "Symbiose". Parallel to the work of "Symbiose", benefits of voltage support by PV systems in the German distribution network will be presented.


Troster E.,Energynautics GmbH | Ackermann T.,Energynautics GmbH | Betz B.,EWR Netz GmbH
IET Conference Publications | Year: 2013

In this paper the usage of a storage device to integrate a large amount of wind power into the existing distribution system of EWR is discussed. In the case study a wind power plant rated at 16 MW is to be connected to the existing distribution system. Normally the plant would be connected via a new cable to the substation, which is roughly 20 km away. In order to reduce the overall cost, EWR decided to find solutions that use only the existing infrastructure. System impacts such as harmonics, flicker, overloading, and voltage issues have been investigated. Almost all scenarios investigated turned out to have a high impact on the power quality of the distribution system and would be outside the allowed boundaries according to the German medium voltage grid code. Various solutions have been investigated; one of them is the usage of a storage device. Storage can be used to solve several issues at once, such as reducing the voltage increase during normal operation or reducing the fast voltage drop when shutting the turbines off. Further improvements can be made by reducing the loading on the lines and transformers and thus reducing the losses in the network. A reduction in system impact through flicker can also be achieved. In the case study it turned out that in order to reduce the system impact to allowed limits according to the German medium voltage grid code, a storage device of 2 MW and an energy capacity of 500 kWh is necessary.


Fursch M.,University of Cologne | Hagspiel S.,University of Cologne | Jagemann C.,University of Cologne | Nagl S.,University of Cologne | And 2 more authors.
Applied Energy | Year: 2013

A strong and intermeshed electricity grid allows the cost-efficient achievement of renewable energy targets by enabling the use of favorable sites and by facilitating the balancing of stochastic infeed from renewables and electricity demand. However, construction of new lines is currently proceeding slowly in Europe. This paper quantifies the benefits of optimal transmission grid extensions for Europe up to 2050 by iterating an investment and dispatch optimization model with a load flow based grid model. We find that large grid extensions, allowing the full exploitation of the most favorable RES-E sites throughout Europe, are beneficial from a least-cost perspective. If the electricity network were to be cost-optimally extended, 228,000. km would be built before 2050 (+76% compared to today). Only for sites located furthest from large consumption areas in Central Europe would the value of grid extensions not always outweigh its costs. Furthermore, the capacity of transmission lines connecting favorable RES-E sites with demand centers is cost-optimally dimensioned to almost entirely export all RES-E generation that exceeds local electricity demand. Only in periods with the highest infeed of fluctuating renewables, electricity is stored. When optimal grid extensions are impeded, storage investments are chosen to a larger extent. © 2012 Elsevier Ltd.


Dubaric E.,Swedish Patent and Registration Office | Giannoccaro D.,Swedish Patent and Registration Office | Bengtsson R.,Swedish Patent and Registration Office | Ackermann T.,Energynautics GmbH
World Patent Information | Year: 2011

This paper reports a study into the use of patent application numbers as indicators of technological development in the field of wind power technology. We show that patent information can be used to analyse the evolution and the level of maturity of this particular technology. The data is gained from databases available at the Swedish Patent and Registration Office (PRV). Three different segments of wind power technology; rotor form, regulation and pitch adjusting, are distinguished and maturity in respective parts is compared to the general technological progress. © 2010 Elsevier Ltd.

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