Arnhem, The Netherlands
Arnhem, The Netherlands
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Zuijderduin R.,Technical University of Delft | Chevtchenko O.,Technical University of Delft | Smit J.J.,Technical University of Delft | Aanhaanen G.,TenneT TSO bv | And 2 more authors.
Physics Procedia | Year: 2012

Due to increasing power demand, the electricity grid of the Netherlands is changing. The future transmission grid will obtain electrical power generated by decentralized renewable sources, together with large scale generation units located at the coastal region. In this way electrical power has to be distributed and transmitted over longer distances from generation to end user. Potential grid issues like: Amount of distributed power, grid stability and electrical loss dissipation merit particular attention. High temperature superconductors (HTS) can play an important role in solving these grid problems. Advantages to integrate HTS components at transmission voltages are numerous: more transmittable power together with less emissions, intrinsic fault current limiting capability, lower ac loss, better control of power flow, reduced footprint, less magnetic field emissions, etc. The main obstacle at present is the relatively high price of HTS conductor. However as the price goes down, initial market penetration of several HTS components (e.g.: cables, fault current limiters) is expected by year 2015. In the full paper we present selected ways to integrate EHV AC HTS cables depending on a particular future grid scenario in the Netherlands. © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Guest Editors.

Van Overbeeke F.,EMforce | De Groot R.,Enexis | Bozelie J.,Liandon Inc. | Slootweg H.,Enexis
IET Conference Publications | Year: 2013

In the framework of an R&D project called "Smart Storage", Enexis has developed a boxed electricity storage system called the Smart Storage Unit (SSU). The SSU is a concrete housing in which a set of batteries and DC/AC converters is pre-assembled. After local installation, 50% of the SSU is below ground level. The thermal concept of the system has been chosen to minimise reliance on active cooling. This paper presents the design considerations, discusses the thermal balance on various time scales, and describes the chosen solution. Extensive functional and cyclic testing of the assembled system was performed in KEMA's Flex Power Grid Laboratory in Arnhem in March- April 2012. These tests have led to modifications on the internal air flow, which have been implemented and have been put to test in December 2012. The paper presents the results and discusses the achieved performance improvements.

Korsman J.,Liandon Inc. | Smits M.,Liandon Inc. | Van Der Ven E.J.H.M.,Thermaflex International Holding B.V.
12th International Symposium on District Heating and Cooling | Year: 2010

The object of this paper is to evaluate heat losses of a flexible PB-PE-PE piping system in the field, compared to a conventional rigid Steel-PUR-PE piping system. The flexible system is optimized in both insulation quantity (thickness) and quality. The heat loss for pairs of pipes in the field, with 70 °C supply and 40 °C return temperature, is based on heat loss measurements in the laboratory and has been evaluated using the multipole method. Since the hydraulic properties of Polybutylene and steel medium pipes differ, hydraulic calculations of a demonstration distribution network, fitted with either system, are made. Total system heat losses for this demonstration network are calculated by summing the product of the heat loss per pair of pipe and the amount of pipe used.

Smits I.M.,Liandon Inc. | Korsman J.,Liandon Inc. | Van Wijnkoop J.T.,Liandon Inc. | Van Der Ven E.J.H.M.,Thermaflex International Holding B.V.
12th International Symposium on District Heating and Cooling | Year: 2010

Different types of pre-insulated pipes are tested on their heat loss values. Three flexible pipes and a rigid pipe are tested. The different heat loss values are compared not only on absolute heat loss, but also on their performance relative to the insulation surface. The heat loss values are measured according to EN 15632 and published as "declared values". The declared values are calculated according to EN 15632 Annex D1-D3. The flexible pre-insulated systems, with PE and PE-X foams, show a variance of up to 5 W/m in the heat loss values. These absolute differences in the system are caused by the outer casing dimensions of the preinsulated pipes. Recalculation to the same outer casing diameters shows a slight advantage for the PE system in service pipes of 32 and 63 millimetres The flexible piping system with the PUR insulation foam on the other hand performs better compared to equally dimensioned flexible PE and PE-X insulation foams. Flexible pre-insulated pipes have a higher heat loss compared to rigid pre-insulated pipes. Recalculation to the same transport capacity [kg/s] and the same outer casing diameter also shows that rigid pre-insulated pipes perform better. However the fact that smaller diameters show a smaller heat loss difference between rigid and flexible pre-insulated pipes is interesting.

Zuijderduin R.,Technical University of Delft | Chevtchenko O.,Technical University of Delft | Smit J.J.,Technical University of Delft | Willen D.,Nkt cables group | And 2 more authors.
Physics Procedia | Year: 2012

The future electricity grid will be more sustainable and it will have more power transmission and distribution capability with more electrical power added from decentralized sources on distribution level and from wind parks and other large sources on transmission level. More interconnections and more underground transmission and distribution will be put up. Use of high temperature superconducting (HTS) power cables provides solutions to many of the future grid problems caused by these trends. In this paper we present an electrical model of a balanced 6 km-long three phase triaxial HTS power cable for the Dutch project being developed by a consortium of Alliander, Ultera™ and TUD. The cable currents in all three phases are balanced by selecting proper twist pitches and insulation thickness. The paper focuses on determining inductances, capacitances and AC losses of the balanced cable. Using the developed model, we also determine the voltage drop as function of the cable length, the neutral current and the effect of the imbalanced capacitances on the current distribution of the Dutch distribution cable. The model is validated and it can be used for accurate simulation of the electrical behaviour of triaxial HTS cables in electrical grids. ©2012 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Guest Editors.

Erbrink J.J.,Technical University of Delft | Gulski E.,Technical University of Delft | Smit J.J.,Technical University of Delft | Seitz P.P.,Seitz Instruments AG | And 3 more authors.
IEEE Electrical Insulation Magazine | Year: 2010

On-load tap changers (OLTCs) are designed to change current from one winding tap to another without interrupting the load and without short-circuiting adjacent taps on the transformer windings. Many OLTCs installed in power transmission systems operate on only one or a limited number of tap positions for an extended time period, and this contributes to degradation of the less frequently used contacts. A routine inspection of an OLTC can involve opening the diverter switch compartment, cleaning the soot-covered insulation, and checking the diverter contacts and mechanisms, but it usually does not include inspection of the tap-selector contacts inside the transformer tank. The addition of an important element to OLTC inspection, namely checking the condition of the OLTC contacts without accessing them physically, is discussed below. © 2006 IEEE.

Erbrink J.J.,Technical University of Delft | Gulski E.,Technical University of Delft | Smit J.J.,Technical University of Delft | Leich R.,Liandon Inc. | And 2 more authors.
IEEE Electrical Insulation Magazine | Year: 2011

On-load tap changers (OLTC) that are in critical condition and require maintenance can be selected on the basis of diagnostic measurement results. Resistance measurements are particularly suitable for assessment of OLTC degradation and to reveal OLTC defects that could lead to failure (see Figure 1). This article discusses dynamic resistance measurements (DRM) on OLTCs. In Part 1 of this series [1], DRM as a diagnostic method for OLTCs was discussed, and a few case studies were presented. In this part the interpretation of the results will be discussed. © 2011 IEEE.

Erbrink J.J.,Technical University of Delft | Gulski E.,Technical University of Delft | Smit J.J.,Technical University of Delft | Chmura L.A.,Technical University of Delft | And 3 more authors.
2010 International Conference on High Voltage Engineering and Application, ICHVE 2010 | Year: 2010

Resistance measurements on power transformers are a widely accepted method for finding winding defects. Continuity of the tap changer contacts can also be checked when the on-load tap changer (OLTC) is operated during the resistance measurement. Resistance measurements that also record the resistance during OLTC operation are called dynamic resistance measurements. This off-line diagnostic method can be used during regular maintenance to assess the condition of OLTC parts not accessible for inspection. Besides condition assessment of inaccessible parts of the OLTC, this method can also be used to detect maintenance errors that could lead to failure. In particular, these measurements are very helpful in finding contact discontinuity, mechanical defects that influence the operation of the tap changer contacts, problems with the switch time and the transition resistors and can find contact degradation in an early stage. This paper elaborates on the analysis of service aged power transformers equipped with an OLTC using dynamic resistance measurements. Interpretation of dynamic resistance results is complicated because a large variety of degradation mechanisms act on the OLTC, which can show differently in the dynamic resistance results. A structured procedure for interpreting the dynamic resistance results is presented in this paper. Distinction is made between discontinued tap changer contacts and contacts with increased contact resistance. First, it is discussed how the location of the defect can be determined from deviations in the dynamic resistance. Secondly, the degradation mechanism is determined that underlies the deviating dynamic resistance. Using this information, the importance of the defect or degradation can be determined, this paper gives an example. Finally, condition indexing is discussed and an application example demonstrates how this way of condition assessment can be implemented. ©2010 IEEE.

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