The Italian system for Power Quality (PQ) monitoring of MV distribution networks described in the previous paper 0042 of the 19th International Conference on Electricity Distribution [1] has been working for almost 3 years on 600 instruments distributed all over the Italian territory. The paper illustrates the results of monitoring over the last three years and shows how the monitoring of events, (especially voltage dips) is going to consolidate the characterization of the Italian MV network from the PQ point of view.

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Electromagnetic interference (EMI) from renewable power systems to the grid attracts more attention especially in the low-frequency range, due to the low switching frequency of high-power inverters. It is significantly important to derive EMI models of power inverters as well as to develop strategies to suppress the related conducted emissions. In this work, black-box modelling is applied to a three-phase inverter system, by implementing an alternative procedure to identify the parameters describing the active part of the model. Besides, two limitations of black-box modelling are investigated. The first regards the need for the system to satisfy the linear and time-invariant (LTI) assumption. The influence of this assumption on prediction accuracy is analysed with reference to the zero, positive and negative sequence decomposition. It is showing that predictions for the positive/negative sequence are highly influenced by this assumption, unlike those for the zero sequence. The second limitation is related to the possible variation of the mains impedance which is not satisfactorily stabilized at a low frequency outside the operating frequency range of standard line impedance stabilization networks.

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