A new solution for the phase and earth fault directional detection used in Fault Passage Indicators (FPI) is presented in this paper. The solution is based on several low power voltage sensors using capacitor on bushing or on head cable or resistive sensors. The principle of the phase directional detection remains on the conventional principle of protection relays (ANSI 67). The main algorithm improvement concerns the earth fault directional detection (ANSI67N), well adapted to low cost sensors and without setting depending on distribution network characteristics. With the proposed earth fault detection algorithm, the direction of the fault, forward or backward, is determined during the first fault transient by analysing the sign of the zero sequence current and the sign of zero sequence voltage. This method can be used with all neutral earthing systems (solid neutral earthed, impedance earthing, low impedance earthing, compensated neutral earthing, unearthed neutral) without using any parameter depending on the neutral system. This method is adapted to radial electrical network or closed-loop network, with or without distributed generators along the feeders. Thanks to high sensibility of the algorithm, the FPI may detect high impedance faults and transient faults, while requiring only low cost voltage sensors. The proposed solution is now implemented in a new RTU range which has been tested on real MV grids.

This paper shows how improving the network management by increasing the level of network automation and control improves the operating efficiency of medium voltage distribution networks. Specifically, the presentation shows the steps to equip gradually the network according to progressive investment capability, from Fault Passage Indicators (FPIs) and remote control, to automatic circuit reclosers (ACRs) and sectionalisers used in a feeder automation scheme to both minimize the number of disturbances and minimize the outage times experienced during these disturbances.

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Strong evolutions are taking place for a modern distribution automation grid, with increased missions generating more and more reasons for cybersecurity. New control technologies with fast and wide area communication will require a modern approach addressing cyber security aspects, for design as well as for operation phases. This study describes the perspectives for the design of distribution automation architecture and devices addressing the cyber security aspect of the modern grid. It refers to topics such as data encryption, secured communication protocol implementation and routine security procedures to protect the distribution grid against cybersecurity attack and unintentional misuses. 1 Actual challenge for modern distribution grids Distribution grids are quickly evolving addressing new values: Enriching feeder capabilities: Deploying intelligent devices on the feeder increases utilities' ability to manage assets remotely. Sophisticated, meaningful data are shared among mobile field crews, remote operators, and maintenance centres thanks to smart communication standards. More accurate information about asset behaviour enables utilities to reduce the number of costly field maintenance visits, and even more, to keep equipment operating efficiently with proactive actions. Optimising assets The MV/LV substation is becoming the cornerstone of distributed automation to help utilities improve power quality and assets' lifespan. Smart controllers (feeder RTU) can maximise the benefits of smart assets by hosting some local automation and by communicating with control centres or with other substations. Increased cybersecurity needs: Distribution grid faces a lot of new challenges to integrate all these aspects in the coming years. Cybersecurity is clearly one of them: † New control technologies with fast and wide area communication will require a modern approach of the distribution grid addressing cybersecurity aspects. † This need is increased by the enlargement of applications addressed, multiplying the number of actors, accesses and data exchanges. † Also interconnection needs are growing tremendously (e.g. interconnections with Information System and not only with control centre) (Fig. 1). Also: † Cybersecurity aspects have to be addressed during definition phase to cover operational phases, but more globally it has to be considered during whole system lifetime, from definition to end of life. (especially as it copes with confidentiality aspects). † Scope itself is quite significant as purpose is to protect against ill-intended attackers but also unintentional misuse. † And all these points have to be addressed ensuring interoperability of components coming from various actors of different maturity levels, over a large diversity of device types, coping with consequent installed basis.