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The increased use of distributed energy generation and storage systems for electrical, heat and cooling systems in households, industry and the Low- (LV) and Medium-Voltage (MV) networks makes an intelligent coupling of the electrical and thermals systems into a so-called hybrid energy system meaningful and necessary. In addition to the economic and ecological aspects, this coupling can be used to increase comfort and to reduce dependencies on fossil fuels and fluctuating energy price. The aim of the presented work is to investigate the effects of various influences on the economically optimal operation of a hybrid energy system (e.g. single-family house) and thus to show the interdependencies and drivers of the hybrid energy system, whereby these are graphically displayed for easier interpretation. [ABSTRACT FROM AUTHOR]

An increased penetration of distributed energy sources for example photovoltaics (PV) leads to new challenges regarding supply of buildings. Besides the common used supply by the public distribution network (large scale generators, transformers) the islanded supply of buildings becomes feasible. Apart from the advantage of a multivalent up to a fully independent power supply in low-voltage distribution systems, questions regarding the functionality of commonly used overcurrent protection devices occur, because of a low short circuit power of the distributed power generators and a too high loop impedance, which is load and time depending. Furthermore the established measurement procedure of the fault loop impedance has to be verified for application in islanded networks with non-linear sources (e.g. inverters). [ABSTRACT FROM PUBLISHER]

The fall-of-potential method is commonly used for grounding measurements. During measurements of extended grounding systems high external influences of the measurement circuit can occur and can lead to measurement errors. Therefore different methods were investigated in the past. In this paper a new one is shown. In fact it is an upgrade of the commonly known beat-frequency method with a combination of a Fourier transform. The new method can avoid the disadvantages of known analysis methods reaching more accurate measurement results — even at environments with high external influences of the measurement circuit. Additional an error estimation of the new method is presented. [ABSTRACT FROM PUBLISHER]

In the field of low voltage systems protection devices like fuses and residual current devices (RCDs) are generally implemented. Because of their high sensitivity residual current devices are very commonly used for protection against electric shock. A part for the fact that inverters may produce voltages with considerable harmonic content also RCDs deserves special attentions. Due to the increasing number of electrical equipment in the low voltage grid producing disturbing currents different RCD types (type AC, A and B) are investigated under certain conditions. For example the influence of disturbing non-sinusoidal, pulse-shaped currents or harmonics in the fault current regarding on the tripping current or on the tripping time of the RCD is analyzed. [ABSTRACT FROM PUBLISHER]