Yaremenko M. Battery management system with dynamic switching

The dissertation is devoted to the development of the theory of storage battery control in the power supply system with a wind turbine based on the use of dynamic switching of batteries to extend their life service, which allows to increase the efficiency of the use of wind energy and to propose simple control algorithms. In the first chapter, the classification and principles of construction of autonomous power supply systems with wind turbines are considered. Influence of environmental parameters on the output power of the wind turbine was studied. Methods of forecasting wind flow parameters and the criteria for assessing the accuracy of forecasting these parameters are analyzed. Battery operation features in power supply systems with wind turbines are considered. Methods of increasing the efficiency of the use of wind energy and batteries are presented. In the second chapter, the assessment and forecasting of the output power of the wind generator and the load power are carried out. Wind speed and load power data were pre-processed, namely, the probability distribution of the function of wind speed and load power were determined; filling gaps of wind speed and load power data were carried out using various methods; a correlation analysis of the data was performed. Forecasting of wind speed and load power time series with different forecast horizons was carried out using the ARIMA model, as well as the average method and the stability method. The third chapter is devoted to the calculation of number of batteries in the power supply system with a wind turbine. Formula for calculating the number of batteries based on Peukert's law is presented. It is shown how the depth of discharge affects the battery capacity available for use during a specific charge-discharge cycle. The effect of ambient temperature on the number of batteries is considered. The methodology for calculating the minimum required number of batteries for uninterrupted power supply of the load is given, taking into account the actual capacity of the battery, which is determined by the duration of its previous operation, and depending on the temperature, depth of discharge, discharge current, discharge time, wind speed forecasting error and battery characteristics, taking into account the stochastic nature wind flow and load power. The break-even calculation of the battery system was carried out. The fourth chapter is devoted to the computer simulation of the operation of the power supply system with a wind turbine and batteries in the Matlab Simulink software environment. A schematic model of a wind turbine using a battery is developed and described, and timing diagrams are given that explain the principle of operation of the circuit. A schematic model of a battery block with a charge-discharge device, built using step-up and step-down converters, and a control system is presented. Operation of the battery switching unit consisting of six identical batteries and the control system that generates the battery switching signals is presented. Simulation of the scheme of the wind turbine with batteries was carried out and a comparative analysis of the duration of uninterrupted power supply of the load with the number of batteries was carried out according to the calculation formula based on the Peukert’s law and without taking into account the Peukert’s law. Graphs of the input and output voltage, as well as the state of the batteries, were presented, which confirmed the theoretical calculations.