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This paper presents an experimental application of LiFePO 4 battery energy storage systems (BESSs) to primary frequency control, currently being performed by Terna, the Italian transmission system operator (TSO). BESS performance in the primary frequency control role was evaluated by means of a simplified electrical-thermal circuit model, taking into account also the BESS auxiliary consumptions, coupled with a cycle-life model, in order to assess the expected life of the BESS. Numerical simulations have been carried out considering the system response to real frequency measurements taken in Italy, spanning a whole year; a parametric study taking into account different values of governor droop and of BESS charge/discharge rates (C-rates) was also performed. Simulations, fully validated by experimental results obtained thus far, evidenced a severe trade-off between expected lifetime and overall efficiency, which significantly restricts the choice of operating parameters for frequency control.

Electrified guided vehicles are normally equipped with regenerative braking devices, while traction lines are supplied by non-reversible substation, thus allowing braking energy recovery only if nearby other vehicles are absorbing power. To enhance the effectiveness of regenerative braking, some energy storage can be installed along the line. Evaluation of its cost effectiveness requires time domain simulations, performed creating simulation models using general-purpose or specialized simulation languages. In this paper, two simulation tools are used. Their respective characteristics compared. The results obtained from both of them are also useful to evaluate the effectiveness of energy storage in a real-life urban case study