State of charge and state of health determination model for a lead-acid battery to be implemented in a management system

Abstract

Battery Energy Storage Systems (BESS) are essential for performing a suitable energy management from renewable sources. They are therefore a necessary element of the new trends of smart grids and micro-grids. This paper proposes a storage system through independent battery strings to increment cycles of use during their lifespan and take advantage of the maximum extracted energy, which has a direct impact on reducing investment and operating costs. Hence, Battery Management Systems (BMS) are indispensable to improve the BESS's performance since they allow working with independent battery strings to connect and disconnect independently, depending on the load requirements. This paper seeks to validate a lead-acid battery model from measurements in terms of State of Charge (SOC), State of Health (SOH) and terminal voltage. Therefore, it is important to check different models that match with these applications' requirements. Since the final selection of the model depends on the parameters that shape it, it is necessary to study different methods for determination of SOC and SOH of the batteries to classify them according to their complexity and uncertainty for the set up advantages and disadvantages of each one. A MATLABSimulink® simulation of a model is made as an example, where the measurement matches the model's elements, allowing us to obtain basic values such as SOC, SOH, depth of discharge (DOD) and terminal voltage simulated under a previously established uncertainty value. This paper leaves a path opened to allow for a future study about the implementation of a BMS to control properly each one of the battery strings that compose a BESS.