Number Of Storage Devices Research Articles

Power Management Strategies in a Hybrid Energy Storage System Integrated AC/DC Microgrid: A Review

The limited availability of fossil fuel and the growing energy demand in the world creates global energy challenges. These challenges have driven the electric power system to adopt the renewable source-based power production system to get green and clean energy. However, the trend of the introduction of renewable power sources increases the uncertainty in the production, control, and operation of power systems due to the erratic nature of the environment. To overcome these meteorological conditions, some support systems, such as storage devices, are integrated with renewable energy sources (RES). A number of storage devices are hybridized to get the hybrid energy storage system (HESS) to get a potential solution for these microgrid problems. For maintaining the robustness and reliability of the power system, proper control, and management of power in the microgrid is very important. In this paper, an analytical study related to power management strategies is given along with different interconnection topologies for the HESS. Analysis and control of storage devices are necessary to avoid the premature degradation of the devices and to get their optimal utilization. Therefore, this article attempts to include different power management schemes used in AC/DC microgrids. Furthermore, various control techniques specific to different energy storage devices are reviewed extensively, which would serve as a complete guide for the design and implementation of a hybrid AC/DC microgrid.

An $n$-PWM DC–DC Converter Modeling: Switched Systems Meets Fourier Series

In this article, we propose steady-state modeling of dc–dc converters driven by multiple pulsewidth modulation (PWM) signals. The proposed dc–dc converter modeling uses a switched state-space framework, and the switching signal discontinuities are represented by a Fourier series to obtain the average model. The advantage of the proposed modeling is that it is not dependent on the dc–dc converter topology, and the dimension of the state-space model does not increase with the number of storage devices. Additionally, the duty cycle and phase displacements among the driving PWM signals can be arbitrary and systematically modeled. The effectiveness of the proposed modeling is supported by simulation and experimental results.

BATTPOWER Toolbox: Memory-Efficient and High-Performance Multi-Period AC Optimal Power Flow Solver

With the introduction of massive renewable energy sources and storage devices, the traditional process of grid operation must be improved in order to be safe, reliable, fast responsive and cost efficient, and in this regard power flow solvers are indispensable. In this paper, we introduce an Interior Point-based (IP) Multi-Period AC Optimal Power Flow (MPOPF) solver for the integration of Stationary Energy Storage Systems (SESS) and Electric Vehicles (EV). The primary methodology is based on: 1) analytic and exact calculation of partial differential equations of the Lagrangian sub-problem, and 2) exploiting the sparse structure and pattern of the coefficient matrix of Newton-Raphson approach in the IP algorithm. Extensive results of the application of proposed methods on several benchmark test systems are presented and elaborated, where the advantages and disadvantages of different existing algorithms for the solution of MPOPF, from the standpoint of computational efficiency, are brought forward. We compare the computational performance of the proposed Schur-Complement algorithm with a direct sparse LU solver. The comparison is performed for two different applicational purposes: SESS and EV. The results suggest the substantial computational performance of Schur-Complement algorithm in comparison with that of a direct LU solver when the number of storage devices and optimisation horizon increase for both cases of SESS and EV. Also, some situations where computational performance is inferior are discussed.

Improved bounds and schemes for the declustering problem

The declustering problem is to allocate given data on parallel working storage devices in such a manner that typical requests find their data evenly distributed on the devices. Using deep results from discrepancy theory, we improve previous work of several authors concerning range queries to higher-dimensional data. We give a declustering scheme with an additive error of O d ( log d - 1 M ) independent of the data size, where d is the dimension, M the number of storage devices and d - 1 does not exceed the smallest prime power in the canonical decomposition of M into prime powers. In particular, our schemes work for arbitrary M in dimensions two and three. For general d, they work for all M ⩾ d - 1 that are powers of two. Concerning lower bounds, we show that a recent proof of a Ω d ( log ( d - 1 ) / 2 M ) bound contains an error. We close the gap in the proof and thus establish the bound.

A model for capacity planning of a comprehensive integrated information system for hospitals and clinics.

Appropriate system sizing is essential to ensuring a reasonable computer response time for end users. A model is discussed that describes the type and number of interactions between user terminals and printers and the central processor for a comprehensive, integrated medical information system. The system modeled includes support to inpatient and outpatient order entry and results reporting for clinical services; registration; admission, disposition, and transfer; patient appointing; pharmacy, clinical laboratory, and radiology; medical record management; and electronic messages. Originally developed for use in benchmark testing of comprehensive systems designed for military hospitals and clinics, the model has been generalized to be applicable to other systems and settings. Results are presented for a routine busy day in a 200-bed teaching hospital providing extensive outpatient services, and a large free-standing clinic. The model results can be applied to several facets of system planning, including sizing of the central processor and communications network, determining the optimal number of storage devices and user devices, and fine tuning the user interface.

Correctness of a distributed transaction system

A distributed transaction system manages information that is dispersed over a number of storage devices. This paper deals with an experimental transaction system designed to satisfy real-time constraints through distributed control of the executions of transactions. Of interest is the correctness of the algorithm for distributed control. Demonstrating the correctness involves showing that the algorithm guarantees the consistency of distributed data, and equally importantly, that every transaction will eventually terminate. Proof of consistency is based on the notion of serializability of transactions while proof of termination is based on the conflict resolution and failure recovery strategies employed by the transaction system.