Topic
State of charge
About: State of charge is a research topic. Over the lifetime, 12013 publications have been published within this topic receiving 201419 citations. The topic is also known as: SoC & SOC.
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TL;DR: In this article, an adaptive observer is proposed to adjust the capacity based on the decaying factor and compensate the error caused by the electrical model, which shows that the observer could accurately estimate the state of charge with capacity fading.
Abstract: State of charge (SOC) of the batteries is a key indicator for battery monitoring and control. Long-term operation of vanadium redox flow batteries may cause ion diffusions across the membrane and the depletion of active materials, which will lead to capacity fading and increase in internal resistance. In previous studies, the capacity fading factor is not considered when designing the SOC estimation observer. This will cause a large error of SOC estimation if the capacity fading is significant. Thus, a selection of an adaptive SOC estimation method considering capacity fading factor is critical. In this paper, an adaptive observer—sliding mode observer—capable of monitoring SOC considering capacity factor is proposed based on a nonlinear electrical model. The observer is designed to adjust the capacity based on the decaying factor and compensate the error caused by the electrical model. A root mean square error of 0.013 V between the measured terminal voltage and estimated voltage is observed while a root mean square error of 0.12 V with the modeled voltage. The mean error between the observed and the modeled capacities is 0.14 Ah. The proposed method shows that the sliding mode observer could accurately estimate SOC with capacity fading.
91 citations
TL;DR: In this paper, the authors proposed a combined economic-degradation model to quantify effects of operational policies (mainly focused on constraining State of Charge (SOC) to prescribed levels in order to reduce effects of aging) on gross revenue, multi-service portfolios, degradation and lifespan of distributed energy storage plants.
Abstract: In an electricity market environment, energy storage plant owners are remunerated for the provision of services to multiple electricity sectors. Some of these services, however, may accelerate battery aging and degradation and hence this needs to be properly balanced against associated services remunerations. In this framework, we propose a combined economic-degradation model to quantify effects of operational policies (mainly focused on constraining State of Charge –SOC– to prescribed levels in order to reduce effects of aging) on gross revenue, multi-service portfolios, degradation and lifespan of distributed energy storage plants that can provide multiple services to energy and balancing market participants and Distribution Network Operators. Through various case studies based on the Great Britain system, we demonstrate that although operational policies focused on battery damage reduction will lead to a revenue loss in the short-term, such loss can be more than compensated by long-term revenues due to a lengthier battery lifespan. We also demonstrate that operational policies to reduce battery degradation mainly affect services related to the energy (rather than balancing) market, which represents a smaller proportion of the overall revenue streams of a distributed storage plant. The model is also used to study effects of ambient temperature fluctuations.
90 citations
14 Mar 2017
TL;DR: In this article, a new bidirectional wireless power transfer (WPT) charging and discharging concept is analyzed for its feasibility in integration at traffic signals, where a string of coils are proposed to be installed beneath the road surface to provide grid-tovehicle and vehicle-to-grid (V2G) services to battery electric vehicles (BEVs) while stopped.
Abstract: In this paper, a new bidirectional wireless power transfer (WPT) charging and discharging concept is analyzed for its feasibility in integration at traffic signals. Classified as quasi-dynamic WPT (QDWPT), a string of coils are proposed to be installed beneath the road surface to provide grid-to-vehicle and vehicle-to-grid (V2G) services to battery electric vehicles (BEVs) while stopped. An experimentally verified lithium-ion battery array and Bidirectional Wireless Power Transfer system are combined to provide a comprehensive simulation under three proposed scenarios. First, four fixed standardized WPT charging levels are evaluated under a Federal Test Procedure-72 city driving profile. Second, a variable charging scenario autonomously adjusts the charging level based on the BEV state of charge. Third, an algorithm is proposed to toggle between charging and discharging based on the BEV psychological and grid retail price to evaluate V2G service viability. For each scenario, a comparison over the maximum driving range per drive cycle and range gained for each consumed kWh is quantified. Moreover, the effect of WPT coil misalignment over the driving performance is investigated and evaluated. This paper concludes that QDWPT at traffic signals is a promising solution to substantially extend the driving range and operating time for city driving especially at high charging levels.
90 citations
TL;DR: In this paper, the authors proposed an intelligent adaptive extended Kalman filter (IAEKF) method that can detect the moment of distribution change of EIS by the maximum likelihood function and then, the ICM is updated based on the EIS after that moment to improve the SOC estimation accuracy.
90 citations
TL;DR: A hybrid method that combines a radial basis function (RBF) neural network, an orthogonal least-squares (OLS) algorithm and an adaptive genetic algorithm (AGA) to estimate the SOC in discharging condition is proposed.
90 citations