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Balzer G.,TU Darmstadt | Neumann C.,Amprion GmbH
CIGRE International Symposium Recife 2011 on Assessing and Improving Power System Security, Reliability and Performance in Light of Changing Energy Sources | Year: 2011

A high rate-of-rise of the transient recovery voltage (TRV) is expected in case of a fault with a serious reactor or power transformer, if a circuit-breaker has to switch off high short-circuit currents which occur if the fault is close to the transformer. The steepness of the voltage is mainly affected by the natural frequencies of the transformer which are in the range of some kHz up to a few ten kHz. Due to the small capacitances between the power transformer and the location of the circuit-breaker the steepness is only weakly damped. The relevant phenomena are called "Transformer limited Faults" which are covered in IEEE C37.011-2005 and ANSI Guide C37.06.1 "Guide for HV circuit-breakers designated definite purpose for fast TRV rise time". This report describes in detail this special switching duty for 380/110 kV coupling transformers installed in a typical air insulated substation. The switching duties dealt with are transformer fed faults with a short circuit on the 380 kV, 110 kV side and on the 30 kV tertiary. The simulation results based on transformer data from practice present the relevant amplitude and voltage rise which occur after first pole clearing. These values are compared with the relevant IEC Standard IEC 62271-100:2008. The investigation demonstrates that various switching duties considered are not covered by this Standard. In particular switching of short circuit currents on the tertiary of 380/110/30 kV transformers generates high current and voltage steepness. The short circuit currents are in the range of the rated values and the voltage steepness is distinctly beyond the rated values. In consequence this stress is normally beyond the ratings of a 30 kV breaker. Derived from these results it is shown which ratings have to be chosen and which measures can be taken to govern this switching duties in question. Source


Losing M.,Amprion GmbH | Schneider G.,RWE AG
VGB PowerTech | Year: 2012

After the disconnection of the power plant Biblis through the KKW-Moratorium 2011 the infeed of reactive power in the area around Frankfurt has been too low. With the rebuilding of the synchronous generator Biblis A into a synchronous motor (synchronous condenser) an adaptable and automatically regulated large reactive power compensation is available for supporting the grid voltage. Source


Fortmann J.,Senvion SE | Pfeiffer R.,Amprion GmbH | Haesen E.,L.E.S.S. | Van Hulle F.,XP Wind | And 3 more authors.
IET Renewable Power Generation | Year: 2015

The need for European Network Codes (NCs) was identified during the course of developing the third legislative package for an internal EU gas and electricity market. The first NC that was initiated by the European Commission covers 'Requirements for Generators' (NC RfG) (ENTSO-E, 2013). After an extensive debate and drafting process across TSOs, DSOs, manufacturers, generation owners, industrial consumers, NRAs and policy makers, ENTSO-E finalised drafting the NC RfG in March 2013 (Further changes, especially with respect to the fault-current injection by wind power plant (WPP) were introduced during the process of transferring NC RfG to a EU Regulation as result of the ongoing discussions between the European Commission and relevant stakeholders. See the remark in Section 3 'Outlook and Conclusion'.). European wind turbine manufacturers represented by EWEA participated strongly in the dialog with ENTSO-E and the stakeholder consultation. A delicate exercise in developing the NC RfG was the appropriate balance between those aspects that need to be defined exhaustively at European level, and the non-exhaustive connection requirements where further specifications are needed at regional level to cover local system needs. Although improvements were seen, significant concerns still remain with the current document, largely focused on the uncertainty from the many non-exhaustive requirements and therefore having to wait for the national Grid Code processes for many parameters. This study explores the need for fault-ride-through capability from a power system security point of view. The requirements stated in the NC RfG, capabilities of WPPs and challenges related to the non-exhaustive requirements of the NC RfG are presented and discussed with the intention to provide technical background information, which may support the national implementation of these requirements. © The Institution of Engineering and Technology 2015. Source


Ringelband T.,Amprion GmbH | Schafer P.,FGH e.V. | Moser A.,RWTH Aachen
Electrical Engineering | Year: 2013

Dynamic thermal rating of overhead lines is a promising approach to increase transmission capacity by calculating weather-dependent thermal ratings (ampacities) of overhead lines in real time instead of using constant ratings. However, knowledge about ampacity is not only needed in real time but also on a day-ahead basis within network operational planning in order to assess network security. As life of humans may be endangered by inadmissible sag of overhead lines when current limits are violated there are high safety requirements concerning thermal ratings. Therefore, ampacity forecasts have to be complemented by a description of forecast uncertainty. So far, there is no method to forecast ampacities on a day-ahead basis considering uncertainty. As a comprehensive description of uncertainty is given by probability densities, this paper presents a novel method to calculate probability density functions of future ampacities based on probabilistic weather forecasts. The method's functionality is proved by application to exemplary data. © 2012 Springer-Verlag. Source


Jost D.,Fraunhofer Institute for Wind Energy and Energy System Technology | Speckmann M.,Fraunhofer Institute for Wind Energy and Energy System Technology | Speckmann M.,Amprion GmbH | Sandau F.,Fraunhofer Institute for Wind Energy and Energy System Technology | Schwinn R.,Fraunhofer Institute for Wind Energy and Energy System Technology
Electric Power Systems Research | Year: 2015

In Germany, the installed capacity of renewable energy sources, especially that of wind and photovoltaic energy, has increased over the past few years and will continue to increase in the future. Due to errors in forecasting wind and photovoltaic energy, the control reserve needed to balance the electricity system will correspondingly increase if control reserves will be sized statically for several months or one year as it is done in most countries today [1-3]. That is because sizing control reserves this way does not consider the fact that there will be hours with a high penetration of wind and photovoltaic which cause a different demand for control reserves than hours with a lower penetration. Therefore, in this work, we present a new probabilistic dynamic method that sizes control reserves for the single hours of the following day making use of forecasts of the power feed-in of wind and photovoltaic. In contrast to similar approaches [2,3] forecast errors of wind and photovoltaic power are not modeled as normal distributions, which does not reflect reality [4-6], but by kernel density estimation to get more realistic distributions. Under a 100% renewable energy scenario for Germany, the control reserve that would be allocated by the dynamic method is compared with the control reserve that would be allocated by a static method. The static method is similar to the probabilistic Graf-Haubrich method, which is applied in Germany today, but can, in contrast to this method, be applied to future scenarios. It is shown that the dynamic method halves the average required control reserve. © 2014 Elsevier B.V. All rights reserved. Source

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