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  • 1.
    Ahmed, Noman
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Haider, Arif
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Van Hertem, Dirk
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Zhang, Lidong
    ABB Power Systems, Ludvika.
    Nee, Hans-Peter
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Prospects and challenges of future HVDC SuperGrids with modular multilevel converters2011In: Proceedings of the 2011-14th European Conference on Power Electronics and Applications (EPE 2011) / [ed] EPE Association, 2011Conference paper (Refereed)
    Abstract [en]

    In order to transmit massive amounts of power generated by remotely located power plants, especially offshore wind farms, and to balance the intermittent nature of renewable energy sources, the need for a stronger high voltage transmission grid is anticipated. Due to limitations in AC power transmission the most likable choice for such a grid is a high voltage DC (HVDC) grid. However, the concept of the HVDC grid is still under active development as different technical challenges exist, and it is not yet possible to construct such a DC grid. This paper deals with prospects and technical challenges for the future HVDC SuperGrids. Different topologies for a SuperGrid and the possibility to use modular multilevel converters (M2Cs) are presented. A comprehensive overview of different sub-module implementations of M2C is given. An overview of short circuit behaviour of the M2C is also given, as well as a discussion on the choice between cables or overhead lines and DC-side resonance issues.

  • 2. Anh, N. T.
    et al.
    Van Hertem, Dirk
    KTH, School of Electrical Engineering (EES), Electric Power Systems. K.U. Leuven, Belgium .
    Driesen, J.
    Transient stability enhancement by TCSC controllers using remote input signals2010In: 2010. ACDC. 9th IET International Conference on AC and DC Power Transmission, 2010, no 570 CPConference paper (Refereed)
    Abstract [en]

    This paper presents a method to improve the dynamic performance of Thyristor-Controlled Series Capacitor (TCSC) regarding transient stability using remote measurement signals. The remote signals are selected based on their effectiveness for damping the first swings. Phasor Measurement Units are used to measure real-time remote signals and transfer those to the TCSC stability control loop. Transient stability studies are performed for the Vietnamese system, and the benefits of applying TCSCs for the stability enhancement are demonstrated. The case studies show the enhancement of the transient stability comparing control using remote control signals in stead of local signals.

  • 3.
    Baradar, Mohamadreza
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Van Hertem, Dirk
    Electrical engineering.
    The Modeling Multi-Terminal VSC-HVDC in Power Flow Calculation Using Unified Methodology2011In: Innovative Smart Grid Technologies (ISGT) Conference, 2011Conference paper (Refereed)
    Abstract [en]

    In this paper, a new unified method for power flowcalculation in AC grids with embedded multi-terminal HVDCsystems based on voltage source converter is proposed. In thismethod all DC and AC equations are solved simultaneously inthe same iteration while there is no need to rely on resultsobtained from other iterative loops unlike the other methods.The method can be applied for any number of converters,any DC network configuration and any converter loss model.The algorithm is implemented in MATLAB and to validate theresults, they are compared to results obtained from the simulationsoftware SIMPOW.

  • 4.
    Baradar, Mohamadreza
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Van Hertem, Dirk
    Electrical engineering, Katholieke Universiteit Leuven, Heverlee, Belgium.
    Kargarian, Amin
    Electrical and Computer Engineering, Mississippi State University.
    Power flow calculation of hybrid AC/DC power systems2012In: Power and Energy Society General Meeting, 2012 IEEE, IEEE , 2012, p. 6343958-Conference paper (Refereed)
    Abstract [en]

    Multi-terminal HVDC systems have recently become an attractive option for interconnection of isolated AC systems such as offshore wind farms and oil platforms to asynchronous large AC systems. This paper deals with power flow calculation (PFC) of hybrid AC/DC power systems where several asynchronous AC systems are interconnected via a common multiterminal VSC-HVDC system. This paper proposes a unified AC-DC approach for PFC of a hybrid AC/DC power system. The proposed approach is then employed for two different analyses, namely a) the separated analysis where the entire hybrid AC/DC system is divided into two groups. The first group (named external AC system) comprises all asynchronous AC systems which are not directly connected to the slack convertor of the DC network, and the second group comprises an AC/DC system where the selected AC system is directly connected to the slack convertor. In this method, a PFC is firstly performed for the the first group, and its relevant obtained results will be used for PFC of the second group. b) the integrated analysis where the entire hybrid system is considered as a unit. Both a) and b) can be used in the practical analysis of the real-size power systems. However, due to practical issues and computational costs the separated analysis may be a more acceptable method. The simulations have been performed using MATLAB, and the obtained results have been compared with those obtained in SIMPOW.

  • 5.
    Ergun, Hakan
    et al.
    Katholieke Univ Leuven, Div ELECTA, Dept Elect Engn ESAT, Kasteelpk Arenberg 10,Bus 2445, B-3001 Heverlee, Belgium..
    Van Hertem, Dirk
    KTH, School of Electrical Engineering (EES).
    Belmans, Ronnie
    Katholieke Univ Leuven, Div ELECTA, Dept Elect Engn ESAT, Kasteelpk Arenberg 10,Bus 2445, B-3001 Heverlee, Belgium..
    CoST Of Wind2010In: 9TH INTERNATIONAL WORKSHOP ON LARGE-SCALE INTEGRATION OF WIND POWER INTO POWER SYSTEMS AS WELL AS ON TRANSMISSION NETWORKS FOR OFFSHORE WIND POWER PLANTS / [ed] Betancourt, U Ackermann, T, ENERGYNAUTICS GMBH , 2010, p. 753-758Conference paper (Refereed)
    Abstract [en]

    Large-scale offshore wind farms are getting more popular due to better wind conditions on the open sea. Several methods exist to connect offshore wind farms to the main electricity grid. In this paper a tool for estimating the overall connection costs for the link between the main grid and a wind farm is shown. The method compares both AC and DC connection options. In order to estimate the overall costs, several technical input parameters such as the transmitted power, the voltage level, connection requirements, etc. must be taken into consideration. Besides the technical aspects several non-technical aspects such as connection distance and prices for the used equipment have to be taken into account. Also the maintenance costs and costs for transmission losses as well as the energy that is delivered to the grid must be considered to get a realistic picture of the overall costs for different connection methods. This paper shows how these overall costs can be estimated and how a cost effective investment can be made. The described methods are implemented in an easy to use tool, which can be used by any project developer to get reasonable first estimate of the costs. The method is developed in Microsoft Excel (R).

  • 6.
    Van Hertem, Dirk
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Eriksson, Robert
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Coordination of multiple power flow controlling devices in transmission systems2010In: ACDC 2010: 9th International Conference on AC and DC Power Transmission, 2010Conference paper (Refereed)
  • 7.
    van Hertem, Dirk
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Eriksson, Robert
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Söder, Lennart
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Coordination of multiple power flow controlling devices in transmission titles2010In: Proceedings of 9th international conference on AC and DC transmission, 2010, Vol. 9Conference paper (Refereed)
    Abstract [en]

    Power flow controlling devices are increasingly present in meshed systems. These devices have strong influence on the power flows throughout the power system. As such, they influence each others operation. In order to make a more optimal and efficient use of their controllability, coordination is needed. This coordination can increase transmission capacity and security, both in steady-state and dynamically. The effect of coordination is shown using two simple examples.

  • 8.
    Van Hertem, Dirk
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Multi-terminal VSC HVDC for the European supergrid: Obstacles2010In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 14, no 9, p. 3156-3163Article, review/survey (Refereed)
    Abstract [en]

    For many, the supergrid is seen as the solution that allows the massive integration of renewable energy sources in the European power system. It connects different remote energy sources to the existing grid while offering additional control. It offers balancing through geographic spread and allows a more diversified energy portfolio. In the meanwhile it increases the security of supply. However, technical limitations exist, and it is not yet possible to construct such a supergrid. Several outstanding issues need to be solved. This paper first describes the potential and need for a supergrid. The paper focuses on a meshed, multi-terminal VSC HVDC, and it is explained why this relatively new technology is believed to be the best suitable one for such a grid. The different difficulties or challenges that still exist are addressed. Not only the remaining technical limitations are addressed, but also the techno-economic, control and operational issues are discussed, as well as some regulatory obstacles.

  • 9.
    Van Hertem, Dirk
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems. Department of Electrical Engineering, Belgium .
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Curis, J. B.
    Despouys, O.
    Marzin, A.
    Protection requirements for a multi-terminal meshed DC grid2011In: Cigrè International Symposium THE ELECTRIC POWER SYSTEM OF THE FUTURE Integrating supergrids and microgrids location, 2011Conference paper (Refereed)
    Abstract [en]

    Multi-terminal high voltage direct current (HVDC) or meshed DC grid is considered to be the preferable option for the much anticipated future supergrid for Europe. This supergrid should connect distant generators to increase the introduction of renewable energy sources and to provide an increased security to the pan- European power system. Although many technical limitations remain, the protection system is often regarded as the most critical one. The protection system for a meshed DC system has particular difficulties compared to the traditional AC system because of the DC current that has no zero crossings and the line impedance that does not limit the fault current. As a consequence, the DC currents will rise much faster and interrupting the fault current is significantly more difficult in the meshed DC than it is in an AC meshed system. Furthermore, traditional protection devices such as impedance relays cannot be used. New alternatives must be found, such as considering a joint strategy between the protection devices and the VSC converter controls. In order to provide a reliable supply of electric energy, the protection system of a meshed DC system should have a number of minimum requirements: fast fault detection, selectivity in opening the correct breakers, and redundancy.

    This paper discusses the different requirements for the protection of a multi-terminal meshed HVDC system. It will provide a list of boundary conditions for such a protection system, as well as an overview of the current state of the technology and the remaining gaps. Some pointers to potential technologies that may be used in the future grid protection are given. The paper will not focus on hardware developments, but will rather indicate the requirements that these devices (or joint set of devices) must fulfill.

  • 10.
    Van Hertem, Dirk
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Ghandhari, Mehrdad
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Delimar, Marko
    Technical limitations towards a SuperGrid - A European prospective2010In: Energy Conference and Exhibition (EnergyCon), 2010 IEEE International, 2010, p. 302-309Conference paper (Refereed)
    Abstract [en]

    In the search for a more sustainable energy supply, renewable energy sources are increasingly introduced into the power system. However, most of these sources are located far from the load centers, and the existing power system is getting overloaded. A supergrid is by many seen as a viable solution that allows a massive integration of these renewable energy sources into the European power system. By connecting energy sources that are located far from each other and by offering enhanced control, balancing services can be delivered. The geographic spread in its turn allows a more diversified energy portfolio. In the meanwhile it increases the security of supply. Although the supergrid has gotten much attention, it cannot be built yet. While the basic technology might seem available, several technical limitations still exist. This paper first describes the potential and need for a supergrid. The paper focuses on a meshed, multi-terminal VSC HVDC, and it is explained why this relatively new technology is believed to be the best suitable one for such a grid. Next the different difficulties or challenges that still exist are addressed.

  • 11.
    Vanfretti, Luigi
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    van Hertem, Dirk
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Nordström, Lars
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Gjerde, J. O.
    A smart transmission grid for Europe: Research challenges in developing grid enabling technologies2011In: Power and Energy Society General Meeting, 2011 IEEE, IEEE , 2011, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Smart grids have attracted significant attention lately, and one can even speak of a hype. However, much of the attention is paid to the distribution side and consumer interaction. Nevertheless, also at the transmission level important improvements can be achieved through farsighted and careful intelligent grid design and implementation. This paper identifies different research areas and their respective boundary interactions in order to enable a practical #x201C;Smart Grid #x201D; implementation in the European power system. Emphasis is placed on three essential aspects of the Smart Transmission Grid. First, the necessary evolution of synchrophasor measurement technology is discussed, as well as the limitations towards and its full integration into power system operation and control. An important aspect to achieve this full integration is the necessity to test and integrate any proposed solution in an open and transparent environment. Secondly, the IT, data and communications paradigm is critically discussed. And lastly, the key questions that are open to the transmission system operators are discussed, specifically regarding the coordination within the pan-European power system and its security. Going beyond the purely academic point-of-view, this paper specifically aims to bring a realistic approach towards research for the transmission network.

  • 12.
    Vanfretti, Luigi
    et al.
    KTH, School of Electrical Engineering (EES), Electric Power Systems.
    Van Hertem, Dirk
    Nordström, Lars
    KTH, School of Electrical Engineering (EES), Industrial Information and Control Systems.
    Gjerde, Jan-Ove
    A Smart Transmission Grid for Europe: Challenges for Developing Grid Enabling Technologies2011In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Renewable and Sustainable Energy Reviews, September 2011Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Smart grids have attracted significant attention lately, and one can even speak of a hype. However, much of the attention is paid to the distribution side and consumer interaction. Nevertheless, also at the transmission level important improvements can be achieved through farsighted and careful intelligent grid design and implementation. This paper identifies different research areas and their respective boundary interactions in order to enable a practical “Smart Grid” implementation in the European power system. Emphasis is placed on three essential aspects of the Smart Transmission Grid.

    First, the necessary evolution of synchrophasor measurement technology is discussed, as well as the limitations towards and its full integration into power system operation and control. An important aspect to achieve this full integration is the necessity to test and integrate any proposed solution in an open and transparent environment.

    Secondly, the IT, data and communications paradigm is critically discussed.

    And lastly, the key questions that are open to the transmission system operators are discussed, specifically regarding the coordination within the pan-European power system and its security. Going beyond the purely academic point-of-view, this paper specifically aims to bring a realistic approach towards research for the transmission network.

  • 13. Westermann, D.
    et al.
    Van Hertem, Dirk
    KTH, School of Electrical Engineering (EES), Electric Power Systems. K.U.Leuven, Belgium .
    Küster, A.
    Atmuri, R.
    Klöckl, B.
    Rauhala, T.
    Voltage source converter (VSC) HVDC for bulk power transmission - Technology and planning method2010In: 2010. ACDC. 9th IET International Conference on AC and DC Power Transmission, 2010, no 570 CPConference paper (Refereed)
    Abstract [en]

    As the value of additional functionality of any new power technology is very case dependent, it is not possible to make general comments on the economics of VSC HVDC applications for bulk power transmission without considering alternatives. Therefore, the paper presents a methodology which can be used to evaluate different investment options, based on the investment cost, the operational costs and a way to include the "non-component based" costs and returns.

1 - 13 of 13
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