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Electrical safety in low-voltage DC microgrids with B-type residual current devices

Czapp Stanislaw, Tariq Hanan, Szultka Seweryn, Szultka Agata, Zaitseva Elena, Levashenko Vitaly

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 2

346--358

EN

Residual current devices (RCDs) are most popular devices used in low-voltage installations for protection against electric shock and fire. In cases of high risk of electric shock the application of RCDs is mandatory. Currently, the spread of local direct current (DC) microgrids is widely considered. This creates new challenges for protective systems, in particular those based on RCDs. The main purpose of the research is to test the operation of B-type RCDs by simulating the conditions that may occur in DC microgrids as well as assessment of the effectiveness of electrical safety with the use of such RCDs. The research has revealed that theoretically identical RCDs in terms of technical data can have different tripping properties, including no reaction to residual direct current, which poses a risk of electric shock. This signalizes the necessity of extension of the normative tests performed by manufacturers. The scope of these additional RCDs tests is indicated, from the point of view of the persons’ safety in DC microgrids.

2

Looped-chain-based active current sharing strategy in DC microgrids

Li D., Liu Y., Gu Y., Qi H.

Archives of Electrical Engineering

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2017

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Vol. 66, nr 3

559--569

EN

The integration of renewable energy sources in modern electric grids have drawn increasing attention nowadays. In order to effectively manage large-scale renewable energy sources and achieve flexible and efficient operation, the concept of microgrids have been proposed. Considering the nature of DC outputs in many distributed energy resources (DERs), DC microgrids have been extensively studied in the past years. Among the operational issues in DC microgrids, current sharing issues have become an important topic since it is highly relevant to the operation of DC microgrids. By adopting a proper design of current sharing strategy in DC microgrids, the current rating violations in each interface converter can be successfully avoided. In this paper, a looped-chainbased active current sharing strategy is proposed to realize high accuracy current sharing in DC microgrids. In particular, the output current is shared between the neighboring interface converters. Hence, following a clockwise or counter-clockwise order, a loopedchain- based control diagram can be established to share the reference value of the output current. A final status in the whole DC microgrid is that the output current of every interface converter is equalized. Hence, the desired current sharing objective can be satisfied. A MATLAB simulation model is established to verify the proposed loopedchain- based active current sharing strategy in DC microgrids.

3

Wykorzystanie mikrosieci prądu stałego do integracji rozproszonych źródeł energii

Paska J., Michalski Ł., Molik Ł., Kocęba M.

Rynek Energii

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2010

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nr 2

118-123

PL

W artykule przedstawiono podstawowe założenia idei łączenia różnych jednostek wytwórczych generacji rozproszonej współpracujących w ramach tzw. "mikrosieci" na przykładzie mikrosieci prądu stałego. W rozdziale drugim zostały scharakteryzowane źródła, które można dołączyć do mikrosieci oraz przedstawiono korzyści jakie płyną z zastosowania sieci prądu stałego do łączenia źródeł. Kolejny rozdział dotyczy aspektów ekonomicznych wytwarzania energii w mikrosieci. Autorzy prezentują zależności służące do wyliczania kosztu jednostkowego energii, który będzie podstawą do odpowiedniego sterowania pracą całego układu. W rozdziale dotyczącym sterowania zaprezentowana została koncepcja komunikacji i przesyłu danych pomiędzy urządzeniami a sterownikiem głównym w mikrosieci.

EN

Basic assumptions of the idea of connection of different generating units of distributed generation, co-operating within so-called "microgrids", on example of DC microgrid, are presented in the paper. In the second part of the paper, sources which can be connected to the microgrid, were characterized, and benefits from DC microgrid for sources integration were presented. The next part of the paper is concerned to the economic aspects of electricity production in microgrid. The authors presented relationships for average unit energy cost calculation, which will be the basis for the proper control of the whole system. In the part concerning control, the concept of communication and data transmission between devices and main controller was presented.

4

Rola i zastosowania układów energoelektronicznych w energetyce odnawialnej

Dmowski A., Biczel P., Szymański B.

Przegląd Elektrotechniczny

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2009

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R. 85, nr 9

68-73

PL

Artykuł omawia rolę i zastosowanie przekształtników energoelektronicznych w energetyce wiatrowej i słonecznej. Ponadto, przedstawiona została tematyka mikrosieci prądu stałego. Autorzy wykazują, że rozwój energoelektroniki jest dziś warunkiem koniecznym dalszego zwiększania udziału nowoczesnych technologii energetycznych, a przede wszystkim odnawialnych źródeł energii w bilansie energii pierwotnej.

EN

The paper discusses the role and utilization of power electronics converters in renewable energy systems - especially systems making use of wind and sun as energy sources. Furthermore, the issue of direct current microgrids is described here. Authors show that development of power electronic converters is necessary for further development of new power technologies and, first of all, increase IN utilization of renewable power sources and their participation in global energy balance.