Battery/Supercapacitors Combination in Uninterruptible Power Supply (UPS)

International audienceThis study presents a study of the reduction in battery stresses by using supercapacitors (SCs) in a 500-kVA rated UPS. We aim at investigating the optimal supercapacitors-battery combination versus the SCs cost. This investigation is threefold; first, supercapacitors and battery models developed using MATLAB/Simulink are presented and validated. Second, the architecture and the simulation of the designed system that combines the SCs and the battery are shown. The supercapacitors are used as high-power storage devices to smooth the peak power applied to the battery during backup time and to deliver full power during short grid outages. By charging the SCs through the battery at a suitable rate, all impulse power demands would be satisfied by the supercapacitors. Third, extensive simulations are carried out to determine the gain in battery RMS current, the gain in energy losses, the energy efficiency and the elimination rate of surge load power. These four performance parameters are determined by simulation and then analyzed. The influence of the SCs recharge on the performance indicators is highlighted. A thorough analysis involving optimal study proposes to draw the optimal SCs number and filter constant from the variation of the aforementioned parameters versus the cost of the SCs

Hybrid power source with battery/supercapacitors for uninterruptible power supply (UPS)

International audienceIn this paper, a power sharing system between the battery and the supercapacitors in a 500 kVA rated uninterruptible power supply is presented. Compared to typical batteries, the supercapacitors can be charged and discharged very rapidly and can supply high current which are important characteristics of an UPS. Supercapacitors are then added as higher energy storage to overcome the full load power during short time grid failures and to boost peak power during backup time of few minutes. The high power demands applied to the battery are then smoothed by the use of a low-pass filter. The potential reduction of the battery stresses is subsequently studied. Mathematical models for battery and supercapacitors pack are set up and validated through experimental and manufacturer data. The UPS waveforms obtained by simulation with MATLAB/SIMULINK are presented and analyzed

Design of power sharing system between supercapacitors and battery in an uninterruptible power supply

International audienceIn this paper we present a strategy to combine supercapacitors with the battery in a 500 kVA rated uninterruptible power supply. First the sizing of the supercapacitors and battery taking into account the UPS specifications is presented. The validation of the supercapacitor and the battery models is carried by using MATLAB/SIMULINK. Second, the power sharing system between the supercapacitors and the battery is presented. The supercapacitors are added as higher energy storage to overcome the full load power during short time grid failures and to boost peak power during backup time of few minutes. The UPS waveforms obtained by simulation are presented and analyzed

Control Strategy for Optimal Combination of Supercapacitors and Battery in 500 kVA rated UPS

Accès à l'article complet (Open Access) : http://www.waset.org/journals/ijeee/v6/v6-16.pdfInternational audienceIn this paper we present an optimal method that combines supercapacitors with the battery in a 500 kVA rated uninterruptible power supply (UPS). Supercapacitors are used as high power storage devices to smooth the peak power applied to the battery during backup-time and to deliver full power during short grid outages. First, supercapacitors and battery models are developed then validated using Matlab/Simulink®. Second, the architecture and the simulation of the designed system combining the two types of storage devices are shown. Finally, extensive simulations are carried out to determine the gain in battery RMS current, the gain in energy losses, the energy efficiency of the global system and the elimination rate of peak power applied to the battery through the battery at a suitable rate, all impulse power demands would be satisfied by the supercapacitors. The influence of the SC's on the performance indicators is analyzed. Optimal combination of two storage devices is obtained taking into account the supercapacitors cost

Utilization of supercapacitors to reduce lead acid battery stresses in UPS

ISBN: 978-1-4673-1168-7International audienceThis work presents the study of the reduction in battery stresses by using supercapacitors (SC's) in a 500 kVA rated UPS. We aim at investigating the optimal SC-battery combination versus the SC's cost. This investigation is threefold; first, supercapacitors and battery models developed using Matlab/Simulink® are presented and validated. Second, the architecture and the simulation of the designed system combining the two types of storage devices are shown. The study emphasizes on UPS autonomous running for grid faults lasting few minutes, the supercapacitors supply the transient demand of power and the battery is responsible for the smoothness requirement of energy. Third, extensive simulations are carried out to determine the gain in battery RMS current, the gain in energy losses, the energy efficiency and the elimination rate of surge load power. These four performance parameters are determined by simulation and then analyzed. They reflect the potential decrease in battery stresses due to the SC's. A thorough analysis involving optimal study proposes to draw the optimal SC's number and filter constant from the variation of the aforementioned parameters versus the cost of the SC's

Influence of aging on electrolytic capacitors function in static converters: Fault prediction method

International audienceThe failure of electrolytic capacitors is the cause of most breakdowns of static converters. The function of these capacitors is to filter and to store electrical energy. Accelerated aging tests showed that the increase of the internal resistance ESR of the capacitors is a good indicator of their faulty state. The filter function is affected by the capacitors wearout on the one hand. At high frequency, the voltage ripple at the terminals of the capacitors increases according to ESR rise. On the other hand, the storage function is not much influenced by the capacitors aging. As static converters work most of the time at variable load, high transient values of the voltage ripple occur when output current changes that can induce false alarms. These transients are verified theoretically and experimentally. In order to avoid these transients effects, we suggest to monitor the fundamental component of the voltage ripple. This latter waveform is the best signature of the capacitors state. The ESR of the capacitors and the time before their failure are deduced from the processing of this waveform with other converter parameters such as input voltage, output current and ambient temperature

Failure prediction of electrolytic capacitors during operation of a switchmode power supply

International audienceElectrolytic filter capacitors are frequently responsible for static converter breakdowns. To predict these faults, a new method to set a predictive maintenance is presented and tested on two types of converters. The best indicator of fault of the output filter capacitors is the increase of ESR, The output-voltage ripple Delta V-o of the converter increases with respect to ESR, In order to avoid errors due to load variations, Delta V-o is filtered at the switching frequency of the converter, The problem is that this filtered component is not only dependent on the aging of the capacitors, but also on the ambient temperature, output current, and input voltage of the converter. Thus, to predict the failure of the capacitors, this component is processed with these parameters and the remaining time before failure is deduced, Software was developed to establish predictive maintenance of the converter. The method developed is as follows. First, a reference system including all the converter parameters was built for the converter at its sound state, i,e., using sound electrolytic filter capacitors. Then, all these parameters were processed and compared on line to the reference system, thereby, the lifetime of these capacitors was computed

An improved Frequency Sharing Strategy Between Battery and Supercapacitors in Electric Vehicles

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Reinforcement learning-based power sharing between batteries and supercapacitors in electric vehicles

International audienceEnergy management of Battery/Supercapacitors (SCs) hybrid energy storage system (HESS) aims to reduce RMS battery current values and enhance the battery lifetime. This paper presents a reinforcement learning (RL) based energy management strategy for Electric Vehicles (EV). This approach allows for learning in real time the optimal power flow distribution between battery and supercapacitors starting from historic of the observation of RMS current of battery. The power management problem is presented with RL formulation verifying the electrical HESS constraints. The presented framework uses the RL technique to control the power flow distribution leading to the minimization of the RMS battery current. Particularly, we propose a methodology that generates optimal frequency sharing policy between battery and SCs taking into account the load variations of the EV dynamically in real time. Numerical simulations carried out on Matlab/Simulink confirmed the convergence of the RMS battery current to the optimal value without any prior knowledge of the driving conditions. The proposed framework aims to adapt automatically the power management policy to the optimal solution