This paper proposes an effective sizing strategy for distributed battery energy storage system (BESS) in the distribution networks under high photovoltaic (PV) penetration level. The main objective of the proposed method is to optimize the size of the distributed BESS and derive the cost-benefit analysis when the distributed BESS is applied for voltage regulation and peak load shaving. In particular, a system model that includes a physical battery model and a voltage regulation and peak load shaving oriented energy management system (EMS) is developed to apply the proposed strategy. The cost-benefit analysis presented in this paper considers factors of BESS influence on the work stress of voltage regulation devices, load shifting and peaking power generation, as well as individual BESS cost with its lifetime estimation. Based on the cost-benefit analysis, the cost-benefit size can be determined for the distributed BESS.

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h i g h l i g h t sInvestigated the voltage drop from Li-ion capacitors during charge and discharge. Demonstrated the importance of loadings of the stabilized lithium metal powders in Li-ion capacitors. Discussed mechanisms for causing the voltage drop of Li-ion capacitors. a b s t r a c tThe IR voltage drop from the anode and cathode of Li-ion capacitors during charge and discharge was studied. Li-ion capacitors were made with activated carbon cathode and hard carbon anode with different loadings of stabilized lithium metal powder (SLMP). It was found that the LICs with high SLMP loadings showed smaller voltage drop than LICs with low SLMP loadings. It was also found that at low SLMP loadings, the IR voltage drops at high cell voltages were smaller than that at low cell voltages; while at high SLMP loadings, small IR voltage drops were obtained for both low and high cell voltages. The electrochemical impedance spectroscopy confirmed that voltage drops are directly related to the internal resistances of Li-ion capacitors.

It is beneficial for photovoltaic (PV) systems to work with energy storage elements especially at residential applications. However, the price for these systems is still high compared to the financial profit which can be gained from such a system. In this paper, the increase cost efficiency of adding a specified size of battery energy storage system to a residential PV system is investigated with an economic Energy Management Strategy (EMS) developed for this application. To derive the most cost effective battery size, a cost function based on a proposed physical based battery lifetime model is developed. In addition, the utility rating has a major impact on the cost calculation, as there are different rating systems available; this paper uses Time of Use (TOU) rating. Real load and PV power profiles are applied to calculate a lifelike economic factor of this system. Finally the simulation results are presented to verify the proposed battery sizing strategy.