Wavelet-based power management for hybrid energy storage system

J. Mod. Power Syst. Clean Energy https://doi.org/10.1007/s40565-019-0529-2 Wavelet-based power management for hybrid energy storage system Masoud MASIH-TEHRANI1 , Mohammad Reza HA’IRI YAZDI2, Vahid ESFAHANIAN2, Masoud DAHMARDEH3 , Hassan NEHZATI4 Abstract A wavelet-based power management system is proposed in this paper with a combination of the battery and ultracapacitor (UC) hybrid energy storage system (HESS). The wavelet filter serves as a frequency-based filter for distributing the power between the battery and UC. In order to determine the optimal level of wavelet decomposition as well as the optimal activation power of the wavelet controller, an optimization procedure is established. The proposed frequency-based power management system moderates the usage of battery current, consequently improving its lifetime. Compared with the CrossCheck date: 28 February 2019 Received: 14 April 2018 / Accepted: 28 February 2019  The Author(s) 2019 & Masoud DAHMARDEH conventional threshold-based power management systems, the proposed system has the advantage of enhanced battery and UC power management. A LiFePO4 battery is considered and its life loss is modeled. As a case study, an electric motorcycle is evaluated in the federal test procedure (FTP) driving cycle. Compared with a conventional energy storage system (ESS) and a state of available power (SoP) management systems, the results show an improvement for the battery lifetime by 115% and 3%, respectively. The number of battery replacements is increased, and the energy recovery is improved. The 10-year overall costs of the proposed HESS strategy using wavelet are 1500 dollars lower, compared with the ESS. Keywords Wavelet filter, Hybrid energy storage system (HESS), Power management system, Ultracapacitor (UC), Lithium life loss model, Battery, Energy storage cost Masoud MASIH-TEHRANI 1 Introduction Mohammad Reza HA’IRI YAZDI Electric vehicles (EVs) have significantly lower mileage cost, reduced air pollution, less petroleum dependence, and better performance over conventional internal combustion engine (ICE) based vehicles [1]. Energy storage system (ESS) is the key factor in EV performance and reliability [2] as well as the main limiting factor during their commercialization process [3]. Due to the heavy, costly and bulky nature of a conventional ESS, EV characteristics, such as mileage is limited [4]. Although, the benefit of using EVs over ICE vehicles is clear in terms of fuel economy and pollution. However, the short service life of ESS and its replacement costs are the limiting factor for commercialization of EVs [5]. With the ongoing development of batteries in terms of increasing the capacity while Vahid ESFAHANIAN Hassan NEHZATI 1 Vehicle Dynamical Systems Research Laboratory, School of Automotive Engineering, Iran University of Science and Technology, Tehran, Iran 2 School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran 3 School of Automotive Engineering, Iran University of Science and Technology, Tehran, Iran 4 Vehicle Fuel and Environment Research Institute, University of Tehran, Tehran, Iran 123 Masoud MASIH-TEHRANI et al. reducing costs, EVs are becoming popular [6]. As a result, more and more efforts are devoted to improve ESS performance [7, 8]. The conventional ESS (battery or ultracapacitor(UC)) has either high energy or high power specifications [9]. Typically, the designer should oversize either the battery or UC, in order to meet both the energy and power demands of the EV, which is not practical due to the increase of cost, size and weight of the system [10]. Therefore, high energy/ power characteristics of the battery/UC are combined to form a new ESS and provide the demand energy/power of the vehicle [11]. This provides an ESS with low cost and high performance while reducing the weight and improving the battery lifetime [12]. Recently, the idea of coupling battery and UC as a hybrid energy storage system (HESS) is proposed in order to moderate current stresses and peaks of the battery. This enables the designer to employ a smaller battery at lower cost while improving its lifetime [10, 13]. The HESS performance is strongly affected by its power distribution system (PDS) [14, 15]. Various HESS power distribution strategies are developed in recent years [16], and this field is getting more and more attention. Besides, there are limited reports on frequency-based control strategies. A dynamic programming strategy is developed in [17] for power distribution between battery and UC. This strategy develops an optimum controller for a specific driving cycle and is useful for off-line applications. Simple controllers such as battery-based [18] and UC-based [19] power management strategies for HESS are proposed, which are based on the battery and UC threshold levels (maximum and minimum power capacities). These controllers are online and show good performance. A model predictive controller for power management of a plug-in hybrid EV with a hybrid ESS is designed in [20]. A cascade and adaptive control strategy is proposed for load compensating of a battery/UC HESS [21]. Adaptive HESS controller is proposed in [22, 23]. Other power management strategies are reported in the literature, such as fuzzy [24], optimal [25], mode decomposition [26], model predictive [27], dynamic programming [28], and neural network [29] strategies. Recently, the authors present a method based on the state of available power (SoP) and predict the power limitations for a given time frame in the future [30]. It is shown that the battery lifetime is improved by 2.6 times. The basic idea of a frequency-based power management strategy is to moderate the battery current. The UC is assigned to provide the high frequency portion of the demand power, while the battery supports the remaining part. Wavelet filter is a powerful yet simple energy management method employed for different applications. The use of wavelet in energy management system for fuel cell 123 vehicle [31], wind power [32], photovoltaic (PV) system [33], and wind-PV hybrid power [34] are reported. A frequency-based power management strategy is proposed for the HESS using Fourier method for a periodic pulsed current load [35]. This paper presents a new HESS power management (frequency-based) system to control the battery current using wavelet filter. A three-level Haar wavelet filter is employed. As a case study, powertrain modeling of an electric motorcycle is introduced in the Section 2. Section 3 discusses the HESS design procedure. A lifetime model for the Lithium iron phosphate (LiFePO4) battery, UC model, and HESS costs are discussed. Section 4 introduces the HESS power management. At first, a conventional UC-based power management is introduced, followed by SoP power management system. The waveletbased power management system is discussed afterwards. Section 5 discusses the principles and tuning of po (...truncated)