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This paper contains an investigation into sympathetic tripping -the undesirable disconnection of Distributed Generators (DGs) (in accordance with the recently-introduced G83/2 undervoltage protection) when a network fault occurs in the vicinity of the DG and is not cleared quickly enough by the network protection (i.e. before the DG's undervoltage protection operates). An evaluation of the severity of and proposal of solutions to the problem of sympathetic tripping on a typical UK distribution power network is presented. An inverter model (as the majority of DGs will be inverter-interfaced) that characterises the fault response of the inverter and its associated protection functions has been developed for use in simulation through exhaustive laboratory testing of a commercially-available 3 kW inverter for DG application; the observed responses have been modelled and incorporated in a power system simulation package. It is shown, when using presently-adopted DG interface and network protection settings, that the risk of sympathetic tripping is high in several future scenarios. To mitigate this risk, the impact of modifying network protection settings is evaluated. This paper has two key findings -determination of the conditions at which the risk of sympathetic tripping is high and evaluation of a technique to mitigate this risk.

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Marine electrical power systems (MEPS) are experiencing a progressive change with increased electrification-incorporation of distributed power generation, high power density requirement, increased storage integration, availability of alternative technologies and incorporation of novel loads to name a few. In recent years, smart grid (advanced land based power systems) concepts have increasingly been incorporated within MEPS to leverage on their proven advantages. Due to the distinct nature of the two power systems, upon incorporation, the solutions need to be further proven by simulations and experimentation. This paper presents two smart grid enabled MEPS test beds at the University of Strathclyde developed to allow for proof of concept validations, prototyping, component characterization, test driven development/enhancement of emerging MEPS solutions, technologies and architectures. The capabilities of the test beds for rapid proof of concept validations and component characterization are discussed by means of two case studies. Drawing on from the two case studies, this paper further presents a discussion on the requirements of systems testing of future more electric MEPS. Index Terms-experimental evaluation, marine electrical power systems, systems testing and test beds.