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Luciano Martini* WG A 3.16 : Members: Heino Schmitt, Convener (Germany), Jorge Amon (Brasil), Dieter Braun (Switzerland), G.C. Damstra (The Netherlands), Karl-Heinz Hartung (Germany), N. Higuchi (Japan), J. Jäger (Germany), J. Kida (Japan) , J. JÄGER (Germany), Mischa Steurer (USA), X. Waymel (France) * CESI RICERCA ** WORKING GROUP A3.16 Without proper mitigation methods, the unavoidable trend of intensifying the interconnections in bulk power transmission systems and the increase in distributed generation penetration will cause an increase of short-circuit currents in power networks. This will cause short-circuit currents to approach, or even exceed, the allowable values based on equipment rating, primarily circuit breaker interrupting capability. Consequently, costly upgrades and replacement of equipment will be necessary. Therefore, there is a growing interest in fault current limiting (FCL) devices rated for medium voltage (MV) and high voltage (HV) applications. The answers to a survey by WG A3.16 among utilities worldwide show a clear increase in the need for fault current limitation especially in HV systems between 110 kVand 145 kV. System protection is an indispensable part of a power system. Protection systems are based on different protection principles and sub-items. Protection coordination studies are performed routinely to confirm the accomplishment of selectivity and sensitivity especially under adverse influence from other devices in the network. Without this confirmation, or without a properly tested and fully operational protection system, a power system will never be energized. Fault current limiters and protection systems go both into action during fault conditions. Hence the use of FCLs is expected to have an impact on parts of the protection schemes and functions in power systems. Therefore, in order to support the introduction of FCL technologies as applicable substation equipment possible interactions between FCLs and protection systems have to be investigated and understood. Different types of FCLs will influence the protection system in a different manner, depending on the type of protection system, the power system configuration, and the type of interactions established. This leads to a rather complicated investigation due to the multiple possibilities for interactions. That is why in order to achieve results in a reasonable amount of time the field of consideration has been narrowly defined and structured formally in order to obtain a framework for this and future investigations. This paper presents the work of CIGRE WG A3.16 which results in a guideline for accomplishing this task. Starting with a limited scope on typical network structures this paper first reviews the most relevant system protection techniques such as overcurrent, distance, differential, and directional protection in the context of FCLs. Consequently, qualifying criteria for the different FCL technologies with respect to the application of system protection are established. Of particular relevance is the behavior of the FCL in the network with respect to the relay measurement function (first cycle and follow current). The concept of the protection zone is reviewed and applied to differentiate the various locations of faults with respect to the FCL location. This is the first step to establish a framework which correlates the influences of different FCL measures, characterized by their previously discussed qualifying criteria, to the various protection functions. Example cases, which are discussed in detail, are illustrating this new framework. Because of its generic attitude, this guideline can be generally applied since it is not restricted to the example cases presented in this paper. It is concluded that while FCL will, in general, interact with the existing protection system the presented methodology helps to clearly identify the specific conditions when such interactions occur.
KEYWORDS Fault current limiter, Protection system, Protection principles, Qualifying criteria, First cycle behavior, Follow current, Influencing phenomena, Pick-up, Processing, Coordination email@example.com *) on behalf of CIGRE WG A3.16. Members: H. Schmitt, Convener (Germany), J. Amon (Brasil), D. Braun (Switzerland), G.C. Damstra (The Netherlands), K.-H. Hartung (Germany), N. Higuchi (Japan), J. Jäger (Germany), J. Kida (Japan) , L. Martini (Italy), M. Steurer (USA), X. Waymel (France)
31 Dicembre 2008
Applicazioni nel campo delle tecnologie innovative (P6 (T&D))