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DC grids are susceptible to DC side faults, which lead to a rapid rise of the DC side currents. DC side faults should be detected in a very short time before fault currents cause damage to the system or equipment, e.g., exceed the maximum interruptible limits of DC circuit breaker. This paper presents a primary and backup protective data-based algorithm. The proposed algorithm depends on the local voltage and current measurements to detect and identify various kinds of faults in the HVDC grid, both in the forward and backward direction. Linear Discriminant analysis (LDA) is used to derive the thresholds and the operational time frames of the primary and backup protection zones of the algorithm. A sensitivity analysis is performed to investigate the influence of the line inductor value on the decision thresholds and on the operational time frame of the algorithm. Furthermore, two statistical approaches utilizing LDA and quadratic discriminant analysis (QDA) methods are proposed to extend the operational time frame of the algorithm. ispartof: pages:854-859 ispartof: 2016 International High Voltage Direct Current Conference (HVDC 2016) pages:854-859 ispartof: 2016 International High Voltage Direct Current Conference (HVDC 2016) location:Shanghai date:25 Oct - 27 Oct 2016 status: published

In recent years the European power system has changed significantly, causing the system to be operated closer to the limits. The transition to more renewable generation is causing power injections at different locations from conventional generation. Secondly the integration of the internal electricity market is causing an increase in flows on interconnections between different areas of the European power system. Furthermore the time needed to construct new infrastructure pushes Transmission System Operators (TSOs) to better utilize the installed infrastructure. As the power system is strongly interconnected, a contingency in one area can affect the whole power system and possibly lead to a wide area black out. Therefore adequate defence plans need to be designed and in place to handle these situations. This paper starts with an overview of the terminology used in defence plans. Subsequently the current status of defence plans in Europe and the preferred sequence of actions to mitigate contingencies, is given based on a survey conducted among several European TSOs. Furthermore his paper gives an overview of how the ongoing changes with renewables, phasor measurement units (PMUs), power flow controlling devices and demand side response can affect the adequacy of defence plans. The authors would also like to thank the iTesla TSOs (RTE, ELIA, National Grid, REN, Statnett, IPTO) for their collaboration in the survey and review of the work. ispartof: CIGRE Science & Engineering vol:5 pages:6-16 status: published

Several preventive and corrective actions are available to the system operator enabling reliability management within a power system. The objective of reliability management is trying to exploit a power system with a minimal socio-economic cost while taking into account the possibility of a contingency on one or multiple elements (e.g. branch, generator) and changing operating conditions. The operating cost is minimised by optimally choosing between all available preventive and corrective actions, most commonly facilitated by an optimal power flow algorithm. This paper presents an overview of the most relevant actions for AC power systems and how to efficiently implement them in an OPF environment. ispartof: Young Researchers Symposium location:Eindhoven date:12 May - 13 May 2016 status: published

Bipolar High Voltage Direct Current (HVDC) is expected to form the backbone of future HVDC grids because it offers advantages in terms of redundancy and added flexibility in developing and operating the system. This comes at the cost of introducing unbalances in the system. However, most DC fault studies until now have assumed a monopolar configuration or a balanced operation of a bipole, and thereby not addressing the challenges that comes with the operation of bipolar systems, such as the influence of unbalanced conditions and grounding relocation on the fault behavior and DC protection systems. This paper deals with DC fault analysis in bipolar HVDC grids, particularly taking those unbalances and grounding relocation into consideration. DC fault behavior under unbalanced conditions and different grounding locations is investigated via simulation studies using PSCAD/EMTDC. The influence of unbalances and groundings on the development of protection systems is evaluated. ispartof: Proc. IEEE YRS 2016 ispartof: IEEE Benelux PELS/PES/IAS Young Researchers Symposium location:Eindhoven, Netherlands date:12 May - 13 May 2016 status: published

ispartof: IET GENERATION TRANSMISSION & DISTRIBUTION vol:10 issue:6 pages:1313-1314 status: published

This paper defines and classifies fault clearing strategies for HVDC grid protection, based on the method of fault current interruption. HVDC grid protection must act on a much shorter timescale than AC grid protection and faces the challenge to interrupt fast rising fault currents without natural zero crossings. Conversely, the HVDC grid protection equipment, such as HVDC breakers or converters with fault blocking capability, offers several degrees of freedom for fault clearing strategies for HVDC grid protection. However, each of these strategies fulfils different objectives and imposes different requirements on HVDC grid components. Therefore, a classification of fault clearing strategies is needed. In this paper, the objectives and requirements for HVDC grid protection are described. Furthermore, constraints on HVDC grid protection are given. Available methods for fault current interruption and protective relaying algorithms are briefly reviewed. Different classes of fault clearing strategies are defined and the options for fault current interruption and protective relaying algorithm for each strategy are given. ispartof: CIGRE location:Lund date:27 May - 28 May 2015 status: published

Due to the importance of reliable electricity supply and the evolutions in the electrical grid, it can be expected that the way in which we assess reliability need to be adapted. At this moment, reliability is commonly assessed deterministically based on an N-1 criterion, while risk-based reliability assessment is widely available in academic works and is used in other industries. However, because of the years of successful use as well as the straightforward and transparent character of the currently used deterministic approach based on an N-1 criterion, stakeholders of the power system are not eager to apply other approaches. Nevertheless, probabilistic assessment is better suited to take into account growing uncertainty and complexity, for instance due to the increased amount of renewable energy sources. Such approaches are well-known for a long time, but difficulties in computation, limitations on the availability of stochastic input data and difficulties in correctly weighing the benefits of using these approaches have prevented them from being used in practice. This paper indicates the need for a comparison between these probabilistic reliability assessments and the deterministic assessment that is currently used. Difficulties in comparing various approaches are shown illustratively through the reliability assessment of a basic test system. The focus of this example is on planning. ispartof: IEEE Young Researchers Symposium location:Gent date:24 Apr - 25 Apr 2014 status: published

Historically defence plans and more specifically load shedding schemes, have always been designed nationally. After the severe disturbance in Europe in 2006, it became clear that the schemes used in the different control zones were not aligned. As a consequence there was an uneven distribution of the load shed in the different zones. A first step in achieving a more unified approach to withstand a large under frequency incidents has, been taken by ENTSO-E. But starting from policy 5 concerning emergency operations, it became clear that still a lot of variation to the proposed scheme is possible. This can be variations in the amount of load shed in each step, the frequency settings at which the shedding takes place and total amount of load that is shed at 48Hz. An overview of the different schemes used in Western Europe in 2006 is given and a comparison is made with some of the scheme currently in use. Starting from this comparison, the question rises of how these schemes would interact. To investigate the consequences of different approaches in designing an under frequency load shedding schemes in an interconnected system, simulations on a two zone system have been performed. From the different combinations simulated, it became clear that different approaches not necessarily lead to a higher total amount of load shed, but that the shedding is more located in specific zones. A unified approach results in similar amounts of load shed but more evenly spread over the zones. It should also be noted that this harmonisation does not imply that exactly the size for the steps for frequency setting for the tripping of the relay should be used. As this could result in a big load disconnection which in turn could lead to an overcompensation. Therefore the band around the linear scheme proposed by ENTSO-E should be defined more clearly. Also the minimum total amount of load that should be shed at 48 Hz should be defined. ispartof: CIGRE Innovation for secure and efficient transmission grids location:Brussels, Belgium date:12 Mar - 14 Mar 2014 status: published

Applying Demand Side Management (DSM) for balancing renewable energy sources (RES), makes it possible to increase energy generation of RES without the need for expensive (spinning) reserve on fossil power plants. The potential of DSM has already been demonstrated for peak shaving, but not for balancing RES. After classifying the loads with their specific constraints for DSM , this paper calculates the potential of DSM for households in Belgium. The calculation is based on measured load capabilities, using laboratory measured profiles of each type of load. The potential has been calculated on a local basis (per dwelling) as well as on a global basis (4.5 million households in Belgium). The calculation also considers the influence of including small and medium enterprises (SME’s). To illustrate the importance of DSM, projections for the years 2020 and 2050 are made. These projections make clear that the potential of DSM should be taken into account in decisions on subsidies for RES. The paper is supported by numerical data for the Belgian situation. ispartof: International Journal of Distributed Energy Resources vol:9 issue:4 pages:383-397 status: published

Electricity markets face major challenges in Europe. While the generation mix for electricity changes, the current market design might not sufficiently facilitate this change. Increased generation from intermittent renewable energy sources affects the electricity market, potentially endangering security of supply including short-term reliability and long-term system adequacy. The need for flexible generation capacity to balance RES and demand variability has risen and must be addressed by the market design. This paper describes the threats for security of supply resulting from possible market malfunctioning of an energy-only market. It includes a condensed overview of capacity mechanisms as additional remuneration mechanisms to overcome the market flaws and to lower impediments for new investments. As an example, the strategic reserve which is planned for Belgium is discussed with respect to the increased share of RES and beginning nuclear phase out in 2015. ispartof: pages:0-0 ispartof: Proceedings of 13th European IAEE Conference 2013 pages:0-0 ispartof: European IAEE Conference 2013 location:Düsseldorf, Germany date:19 Aug - 21 Aug 2013 status: published

With increasing power generation out of renewable energy sources, there is a rising interest to investigate their impact on the power system and its control. In this paper, both the impact on frequency control and the capability to deliver frequency support by renewables is presented. A test grid is used to also investigate the variation of system inertia as a function of time. It is shown that by integrating renewables in the generation mix, the frequency support deteriorates, but through additional control, the frequency support can be improved. Finally the control of an inertialess grid is shortly described and some recommendations for future research are given. ispartof: Young Researchers Symposium in Electrical Power Engineering location:Delft, The Netherlands date:16 Apr - 17 Apr 2012 status: published