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AIGNER, M., RAUNIG, C., SCHMAUTZER, E., FICKERT, L.
SMART GRIDS – CONSIDERATIONS REGARDING PROTECTION OF ELECTRICAL INSTALLATIONS AND SAFETY IN CASE OF DECENTRALIZED POWER SUPPLY
KOMUNALNA ENERGETIKA / POWER ENGINERING, 19
Parallel to the progress of information- and communication technology in recent years, energy production and energy distribution get more economic and efficient; so called Smart Grids get more attention. The focus of the Smart Grid infrastructure lies in the increased involvement of decentralized power generation, exemplarily photovoltaic plants, small hydro power generators or stirling engines in the low-voltage or medium-voltage network. Due to the increased integration of distributed (renewable) energy generation systems, a significant contribution concerning the reduction of CO2 emissions claimed in the 20-20-20 targets and transmission losses is provided.
An important advantage of Smart Grids is the possibility of a multivalent up to a fully independent power supply for islanded grids and microgrids. In case of a failing (separation from the distribution network) a certain degree of power can be principally maintained by decentralized feed-in. Short circuit currents from distribution transformers and additional short circuit currents from decentralized sources (bidirectional current flow) can lead to a incompatibility with existing protection systems.
Therefore the increased integration of decentralized generation requires new considerations regarding protection systems in terms of personal safety and safety of electrical equipment.
The neutral point treatment of decentralized sources, transformers and uninterrupted supply units in combination with distribution transformer is important for security of networks and personal safety.
This paper shows exemplary the effects of a missing neutral point to earth connection (earthing) of decentralized generators in case of parallel supply.
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