Batteries in hybrid power applications that include intermittent generators, such as wind turbines, experience a very irregular pattern of charge and discharge cycles. Because battery life is dependent on both depth and rate of discharge (and other factors such as temperature, charging strategy, etc.), estimating battery life and optimally sizing batteries for hybrid systems is difficult. Typically, manufacturers give battery life data, if at all, as cycles to failure versus depth of discharge, where all discharge cycles are assumed to be under conditions of constant temperature, current, and depth of discharge. Use of such information directly can lead to gross errors in battery lifetime estimation under actual operating conditions, which may result in either a higher system cost than necessary or an undersized battery bank prone to early failure. Even so, most current battery life estimation algorithms consider only the effect of depth of discharge on cycle life. This paper will discuss a new battery life prediction method, developed to investigate the effects of two primary determinants of battery life in hybrid power applications, varying depths of discharge and varying rates of discharge. A significant feature of the model is that it bases its analysis on battery performance and cyclemore » life data provided by the manufacturer, supplemented by a limited amount of empirical test data, eliminating the need for an electrochemical model of the battery. It performs the analysis for a user-prescribed discharge profile consisting of a series of discharge events of specified average current and duration. Sample analyses are presented to show how the method can be used to select the most economical battery type and size for a given hybrid power system application.« less

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Battery Life Prediction Method for Hybrid Power Applications: Preprint

Socio-techno-economic design of hybrid renewable energy system using optimization techniques

Smart grid is a technology for reliable integration and intelligent control of multiple generation units where the loads spread across a non-uniform or a uniform distribution network. The basic frame work of a smart grid is made to ease the complexity of integration of Distributed Renewable Energy Sources (DRES) with greater grid penetration, reduction of transmission losses, optimized energy capacity expansion with better demand side management and hierarchical control for grid security. Smart grids consists of four unique features which can be given as Integration, Control, Communication and Metering (ICCM). Integration refers to connection of heterogeneous type of energy sources with AC or DC grid using appropriate converters. Power output of the DRES is dependent on climatic conditions like wind speed and solar irradiance. Controls in smart grids are made intelligent to extract the maximum power from the sources, operational scheduling of energy sources and overloads, control of transients, real and reactive power. For effective operation of the diverse smart grid, communication between various control nodes is necessary. Communication standards for smart grids usually are set by protocols, and most of them involve the interconnection of Secure Communication Line (SCL) to the main control unit by LAN (Local Area Network), HAN (Home Area Network), and WAN (Wide Area Network). The interconnection should be accompanied with a firewall at various levels for the cyber security of the smart grid. Smart metering employed in smart grids provides additional information of the electrical energy consumed compared to conventional energy meters. Smart metering can measure the energy parameters of the load remotely and transfer the data through the communication network. This paper presents different methods of ICCM in smart grid.

http://biocpv.ex.ac.uk/Papers/2014_Reddy_RSER.pdf

A review of Integration, Control, Communication and Metering (ICCM) of renewable energy based smart grid

Optimal power flow management for distributed energy resources with batteries

With the advancement in technologies, the power requirement around the globe is tremendously increasing, putting extra loads on grids. The existing grids cannot bear that load and also do not provide the interface with Distributed Renewable Energy Sources (DRES). Building new lines and substations alone do not serve the purpose of overcoming energy shortfall. Thus a major transformation in electricity infrastructure is need of the hour to meet the ever growing demands of electricity. Converting current power management system to a smart autonomic system is pertinent to achieve an increasing amount of renewable energy generation. This paper presents a comprehensive review of advances in control of smart grids. Various robust and adaptive strategies are spotlighted with a detailed description of control of overloads and power smart grids. Also, power generation, storage and management techniques and development of operational schedule of sources and loads are elaborated. Recently reported systems and Information and Communication Technologies (ICT) techniques in smart grid are highlighted. Renewable energy has potential to eliminate the current electricity crisis in Pakistan's energy sector. The solar, wind, hydro and biogas/biomass are the alternative energy resources found abundantly in the country, which have tremendous potential to offer environment-friendly energy solutions. This in-depth study reveals that a lot of opportunities and potential of smart grid technology exist in developing countries like Pakistan that need to be exploited so as to cope with energy crisis.

Opportunities and challenges in control of smart grids – Pakistani perspective

An investigation of variable speed operation of diesel generators in hybrid energy systems

This paper summarizes the latest University of Massachusetts work on the analytical modeling and experimental testing of battery component models for hybrid power systems. An extension of the Kinetic Battery Model (KiBaM), developed at the University of Massachusetts is presented. The original model was based on a combination of phenomenological and physical considerations. As described in this paper, the modified KiBaM can now model the sharp increase in voltage near the end of charging, and the sharp drop in voltage when the battery is nearly empty. This model may readily be coupled with a DC load or charging source (such as a DC wind turbine or photovoltaic panels) to determine the corresponding DC bus voltage. For example, it is now an integral part of the DC bus section of the University of Massachusetts HYBRID simulation models. The paper describes the development of the extensions to the KiBaM model and the method of determining the constants from test data. On the experimental/applications side, it includes an illustration of how the constants are obtained from representative data (using a specially developed testing apparatus), and an example of how the model can be used.

W.A. Stein

Papers

An investigation of variable speed operation of diesel generators in hybrid energy systems

Recent progress in battery models for hybrid wind power systems