Italian Experience on Electrical Storage Ageing for Primary Frequency Regulation

Abstract

Abstract:The paper describes the results of different types of ageing tests performed by Terna (the Italian Transmission System Operator) applied to several electrochemical technologies, namely lithium-based and sodium-nickel chloride-based technologies. In particular, the tested lithium-based technologies exploit a graphite-based anode and the following cathode electrochemistries: lithium iron phosphate, lithium nickel cobalt aluminium, lithium nickel cobalt manganese, and lithium titanate. These tests have been performed in the storage labs located in Sardinia (Codrongianos) and Sicily (Ciminna). The aim of the storage labs is intended to give the electrical grid ancillary services, for example, primary frequency regulation, secondary frequency regulation, voltage regulation, synthetic rotational inertia provision, and many more. For the primary frequency regulation service, the ageing of the batteries is difficult to foresee as the ageing tests are not standardized. The authors proposed some novel cycle types, which showed that, in several cases, the frequency regulation cycle ages the batteries much more than the standard cycle. The standard cycle definition has been adopted in the paper to identify a battery cycle test that was carried out to uniformly compare and rank the different technologies. Moreover, sodium-nickel chloride batteries are unaffected by the types of cycle and have a negligible ageing. In addition, lithium manganese oxide and lithium titanate batteries show very good behaviour with a slight degradation of the dischargeable energy, irrespectively of the type of cycle. Inversely, lithium nickel cobalt aluminium technology shows a considerable ageing and a strong dependence on the cycle types. Even if the theoretical explanations of such aging behaviours need time to be understood and expounded, the authors are convinced that the scientific community should become aware of these experimental results.

Li-Ion Battery-Flywheel Hybrid Storage System: Countering Battery Aging During a Grid Frequency Regulation Service

“…discharging the battery when the network frequency falls below its threshold value and vice versa. Figure 1 shows a 24-h-long frequency variation in a real network bus [14]. The main electrical characteristics of the tested batteries are reported in Table 1.…”

“…However, the result of the above presented analysis suggests that the battery aging effects caused by frequency regulation cycles could be related to the energy amount that has to be exchanged with the grid, which is proportional to the Ah throughput. Moreover, by taking into account the experimental evidence that emerged in the measurement campaign presented in [14], the frequency of the power supplied by the battery should be limited as well in order to counter the battery aging during frequency regulation cycles.…”

“…Moreover, many contributions in literature focus on the possibility to counteract the grid regulating energy decrease due to renewable energy plants by exploiting the power supplied by electrochemical energy storage installations [1][2][3][4][5][6][7][8]. This solution seems to be very effective, but recent studies demonstrated that battery aging during a grid frequency regulation operation could be higher than expected and difficult to foresee, especially for some battery technologies, including lithium-iron phosphate, lithium-nickel cobalt aluminum and lithium-nickel cobalt manganese technologies [14]. The flywheel system suitability for grid services has already been recognised for some time [15].…”

Battery Storage-Based Frequency Containment Reserves in Large Wind Penetrated Scenarios: A Practical Approach to Sizing

“…Further on, an economic assessment of the BESS unit, which is directly related to the amount of available regulating power that can be bid on the electricity market, could be performed. In [18], lifetime models of different types of BESS chemistries, including one based on Li-ion technology, were presented. A lithium-ion BESS lifetime model based on accelerated ageing tests is developed in [6].…”

“…Similar economic analysis of the BESS unit was carried out in [4]. However, the BESS units that were investigated in the aforementioned studies [4,6,[18][19][20][21][22], already had fixed sizes. Optimal sizing of BESS unit is one of the key aspects to consider in wind dominated power systems.…”