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• More than double as many overvoltage events on Sundays compared to weekdays. • No apparent effect of highly variable irradiance on overvoltage incidence. • Duration of overvoltage events matches high irradiance events and last a few minutes. • Frequently reporting AMI do not indicate weak grid segments. If rooftop-installed solar energy systems generate more energy than locally consumed, the excess is fed into the electricity grid, increasing the voltage. Rising penetration levels of solar photovoltaic (PV) systems increase voltage levels, thereby threatening power quality. The extent to which solar PV cause grid issues in actual, nation-wide distribution grids, and how these issues correlate with cloud conditions and irradiance variability has yet to be quantified. This work provides a spatial and temporal characterization of overvoltage events linked to solar PV, using novel data sources. The analysis is based on over 200,000 events from advanced metering infrastructure (AMI) spanning 1/3rd of the Netherlands, combined with satellite observations and 1-minute irradiance measurements. As a result, we find that the typical duration of overvoltage events is in the order of 5 min, and frequently-reporting meters are geographically dispersed. While overvoltages are driven by high PV generation, we do not find evidence that local, short-term irradiance peaks result in additional events as compared to clear sky conditions. However, we do find that median overvoltage event occurrence on Sundays is more than 2.1 times that of weekdays, which can be related to low energy consumption. Our findings indicate PV hosting capacity to be reached throughout the service area simultaneously, and surprisingly show no reduction in event duration by inverter- or grid control. Notably, while a sharp increase in occurrence is observed, overvoltage events are still scarce in absolute terms, with only 0.1% of the AMI reporting more than 10 events in spring-summer 2020. [ABSTRACT FROM AUTHOR]

• In this paper, the findings and conclusions of a complete failure investigation process and mitigation analysis are presented with respect to the switching of 33kV shunt reactors by means of vacuum circuit breakers. • Detailed description of the system under study as well as operational aspects are given. Next to that, the EMT model, its validation and the analysis results are discussed. • Description is given on the set-up of the on-site transient measurements and the method used for the analysis of the measurement data. Main findings and conclusions of the measurement campaign are presented as well. • The results of the desktop study are presented with respect to the application of RC surge suppressors as a remedy against the VCB multiple re-ignitions. Switching of (small) inductive currents by means of vacuum circuit breakers may lead to multiple re-ignitions. This is the result of the ability of the interrupter's quenching capability, which generates steep overvoltages that can stress the equipment insulation. Should no mitigation measures be applied, the equipment is exposed to a high risk of failure. In this paper, the findings and conclusions of a such a failure investigation and mitigation analysis are presented, referring to multiple cable connector failures in 33kV shunt reactor installations in the Netherlands. [ABSTRACT FROM AUTHOR]