Stand-alone Power System Research Articles

Hybrid wind–photovoltaic–diesel–battery system sizing tool development using empirical approach, life-cycle cost and performance analysis: A case study in Scotland

The concept of off-grid hybrid wind energy system is financially attractive and more reliable than stand-alone power systems since it is based on more than one electricity generation source. One of the most expensive components in a stand-alone wind-power system is the energy storage system as very often it is oversized to increase system autonomy. In this work, we consider a hybrid system which consists of wind turbines, photovoltaic panels, diesel generator and battery storage. One of the main challenges experienced by project managers is the sizing of components for different sites. This challenge is due to the variability of the renewable energy resource and the load demand for different sites. This paper introduces a sizing model that has been developed and implemented as a graphical user interface, which predicts the optimum configuration of a hybrid system. In particular, this paper focuses on seeking the optimal size of the batteries and the diesel generator usage. Both of these components are seen to be trade-offs from each other. The model simulates real time operation of the hybrid system, using the annual measured hourly wind speed and solar irradiation. The benefit of using time series approach is that it reflects a more realistic situation; here, the peaks and troughs of the renewable energy resource are a central part of the sizing model. Finally, load sensitivity and hybrid system performance analysis are demonstrated.

A Novel Supervisory Command Integration for Large-Scale of a Solar Energy/Fuel Cell/Ultra-capacitor

Abstract: In this paper, we present a Stand-alone Power system (SPS). The goal of this system is the ensuring of the electricity production without interruption in remote areas. It consists generally of a five components which are a solar energy, an energy storage that combines a water electrolyze and a storage gas tank, an energy conversion based on a proton exchange membrane fuel cell (PEMFC), an ultra-capacitor storage (UCap) and a suitable energy management unit to manage and to supervise the system operation of the hybrid system. This combination can ensure the optimal behavior of the load with the respect of the slow dynamics of the PEMFC. The integration UCap ensures the elimination of the slow dynamics of the PEMFC during the transient event. A Novel supervisory command is proposed. The modeling of the overall system is given and the obtained results are presented and discussed. Keywords : Solar Energy, Proton Exchange Membrane Fuel cell, Ultra-capacitor, Supervisory Command, Energy Management.

Feasibility Analysis and Simulation of a Stand-Alone Photovoltaic Energy System for Electricity Generation and Environmental Sustainability – Equivalent to 650VA Fuel-Powered Generator – Popularly Known as “I Pass My Neighbour”

Photovoltaic (PV) power system can be used to replace wholly 650VA generator for electricity generation for household use in Nigeria. This paper presented the feasibility analysis of load data and simulation study of a stand-alone PV power system that produced the electrical needs of a household. This study is based on designing of PV energy system for household use. The patterns of load consumption within the household were studied and suitably modeled for simulation. The simulation study indicates that energy requirements to provide electricity which is equivalent to 650VA generator for household use in Nigeria can be accomplished by 520W solar PV array, 2312 Ah nominal capacity battery, and a 1kW DC/AC inverter. This would be suitable for deployment of 100% clean energy for environmental sustainability and uninterruptable power performance in the household. The results of this research show that, with a low-power consuming appliances, it is possible to meet the entire annual electricity demand of a single household solely through a stand-alone PV energy supply. Installing solar panels by most Nigerian home can significantly reduce home reliance on government power thereby reduce the strain on the current capacity of our power generation infrastructure. A detailed design and description of the system were presented in this paper.

Stand-Alone Power Systems with IGBT Inverter

This article is an overview of research in fault diagnosis, detection, and reconfiguration. The review particularly focuses on power electronic applications and drives. Diagnostics of systems with conventional inverter drives (CID) is considered because knowledge of fault diagnosis in CIDs can be used for application in other inverter drive topologies; therefore, several techniques of fault diagnosis and reconfiguration in CIDs are analyzed.

Bifurcation Analysis and Experimental Study of a Multi-Operating-Mode Photovoltaic-Battery Hybrid Power System

Stand-alone hybrid renewable power generation systems have gained popularity in recent years. However, due to the intermittent nature of the renewable resources, hybrid renewable power generation systems are often designed to operate with multiple structures and multiple operating modes. The design for stable operation of such systems requires consideration of the stability conditions for all possible structures and operating modes. A stand-alone photovoltaic-battery hybrid power system is studied for illustrating the possible complex behavior in this paper. We reveal smooth bifurcation, including slow-scale Neimark–Sacker bifurcation, fast-scale period-doubling bifurcation as well as coexisting bifurcation. Under certain conditions, when the system switches its operating mode, a nonsmooth bifurcation, manifested as a jump between stable and unstable behavior, can also be observed. Moreover, a detailed analysis based on a discrete-time mapping model is performed to evaluate the stability boundaries of the system. Extensive experiments verify the analysis and simulated results.

Optimal sizing of hybrid PV/diesel/battery in ship power system

Owing to the strict restrictions imposed by the Marine Pollution Protocol and the rapid development of renewable energy, the use of solar generation and energy storage systems in ship power systems has been increasingly attracting attention. However, the improper sizing of a hybrid power generation system in a ship power system will result in a high investment cost and increased greenhouse gas emission. This paper proposes a method for determining the optimal size of the photovoltaic (PV) generation system, the diesel generator and the energy storage system in a stand-alone ship power system that minimizes the investment cost, fuel cost and the CO2 emissions. The power generation from PV modules on a ship relies on the date, local time, time zone, longitude and latitude along a navigation route and is different from the conditions of power systems on land. Thus, a method, which takes the seasonal and geographical variation of solar irradiations and temperatures along the route from Dalian in China to Aden in Yemen into account, for correcting the output of PV modules is developed in this paper. The proposed method considers five conditions along the navigation route to model the total ship load. Four cases are studied in details to demonstrate the applicability of the proposed algorithm.

Dynamic control and advanced load management of a stand-alone hybrid renewable power system for remote housing

This paper proposes an advanced energy management strategy for a stand-alone hybrid energy system. The considered hybrid system includes a photovoltaic panel, a fuel cell, an electrolyzer, a battery bank and a supercapacitor. The proposed power management system aims to control the energy flow within the system and decides the amount of the load power shared with each power source. The system control is implemented in two parts: a central power flow controller that provides overall control of the power system and a local loads controller, which controls the different loads according to the energy balance of the system. The hybrid power system has been tested by simulation using models implemented in Matlab/Simulink software. The simulation is performed over a short and a long period of time in order to evaluate the performance of the dynamic controllers and the effectiveness of the management strategy. For a long simulation period, a house located in the province of Batna (35°33′N 6°10′E) has been taken as a case study with a deep study on real load profile for an average house with all required weather data with respect to the location. The simulation results confirm the efficiency of the proposed control strategy, as it increases the reliability of the system and improves its energy balance.

An improved particle swarm optimisation algorithm applied to battery sizing for stand-alone hybrid power systems

Abstract Stand-alone hybrid power systems with renewable energies are an economic alternative to the main electricity grid where the extension of the grid is too costly or the small local consumption would not justify it. Properly sizing the battery of the systems is an important step to guarantee their reliability and low cost. This paper accepts the dispatch-coupled sizing method by integrating the battery into the operation of the generation units in the system, and formulates this application problem using optimal control. Two major renewable energy sources – solar photovoltaic panels and wind turbines – are considered, together with traditional diesel generators. Penetration level is used as the lever to indicate the different integration degrees of renewables in the system. A particle swarm optimisation (PSO) algorithm is adapted and improved for this specific application. The numeric results of the system planning are benchmarked using an economic indicator, the levelised cost of electricity, to address the real-world system.

A developed energy management strategy for a stand-alone hybrid power system for medium rural health building

Summary This paper deals with load side management strategy for (photovoltaic–wind–diesel) hybrid system for medium rural health building located in the Sahara region. The paper presents an overview about geographic and climate data of the location and develops a typical load profile of electrical energy, depending on a real investigation of daily electricity consumption. The base of the proposed management strategy is the control of the air conditioning system and the non-critical lighting of the building as they consume more than 50% of the total power consumption. The result shows that the reduction in the peak consumption is about 20% using the proposed management strategy, which has significant economical, technical, and environmental benefits. Copyright © 2015 John Wiley & Sons, Ltd.

Nanostructured (Mg,M)2SiO4 As Cathode Material in Mg Ion Batteries

Rechargeable Li-ion batteries are already widely used, and the dominating solution for automotive as well as portable, high-power applications due to the superior power density. However, several challenges of Li-ion battery technology are yet to be overcome, e.g. with respect to cost, resource availability, safety issues related to risk of thermal runaway of batteries and the limited temperature window of Li-ion batteries due to electrolyte deterioration at low temperatures. Although expected to dominate the portable battery market in the foreseeable future, the above mentioned drawbacks of Li-based batteries mean they have limited suitability in several markets, including stationary energy storage systems and auxiliary power applications where low cost and high reliability under a wide temperature range are more important than low weight and high power density. There is therefore a need for development of new battery types, specifically aimed at low cost markets. Batteries based on magnesium and other divalent metal ions, with the option of transferring two electrons, compared to the one electron transferred in Li-ion batteries, were introduced around 2000 by Aurbach et al.[1] and represent a promising solution for future low cost, high energy density batteries. Rechargeable Mg-batteries are not yet commercially available, but have a theoretical energy density in the range of 100 Wh/kg[2] for Chevrel-phase cathodes and up to 500 Wh/kg for MgMnSiO4 cathodes[3]. Still, fundamental research is needed in order to produce high-performance batteries which are also stable and recyclable. In this aspect, an interdisciplinary approach covering modeling, innovative material synthesis routes and advanced experimental characterization techniques is a powerful combination which is herein proposed for the development of low cost novel Mg-ion batteries. Such developments will be beneficial for a wide range of applications, mainly stationary, that require use of batteries, such as for storage of renewable energy from intermittent energy sources (solar, wind and wave), stand-alone power systems, telecommunication base stations, auxiliary power, etc. In this work, selected (Mg,M)2SiO4 (M=Mn or Co) materials are synthesized through an advanced sol-gel route as well as flame spray pyrolysis, aiming to obtain enhanced electrical conductivity. The developed cathode materials are characterized electrochemically by using Mg alloys as the anode and a state-of-the art electrolyte. In-situ X-ray diffraction (XRD) is used to characterize phase evolution in the materials during cycling. The effect of different synthesis methods on morphology, phase purity, crystal structure and electrochemical properties will be presented. [1] D. Aurbach, Lu, Z., Schechter, A., Gofer, Y., Gizbar, H., Turgeman, R., Cohen, Y., Moshkovich, M., Levi, E., Nature 2000, 407, 724-727. [2] D. Aurbach, Y. Gofer, Z. Lu, A. Schechter, O. Chusid, H. Gizbar, Y. Cohen, V. Ashkenazi, M. Moshkovich, R. Turgeman, E. Levi, Journal of Power Sources 2001, 97-98, 28-32. [3] Z. Z. Feng, J. Yang, Y. Nuli, J. L. Wang, X. J. Wang, Z. X. Wang, Electrochemistry Communications 2008, 10, 1291-1294. Acknowledgements Financial support is gratefully acknowledged from the Research Council of Norway, grant number 221785/F20.

Structure and Surface Chemistry Optimization of Graphite Electrodes for High-Voltage Dual-Intercalation Batteries

Existing standalone grid-level power systems rely on inefficient operation of diesel generators or expensive traditional battery technologies. Dual-intercalation batteries, which rely on high-voltage ion insertion into both cathodes and anodes, offer a promising electrical energy storage alternative. The respective 372 mAh/g and 90 mAh/g capacitances for cation and anion intercalation offer grid-level charge storage densities, implementation of affordable and available materials, and simpler disposal procedures for optimized and reliable energy storage systems[1]. Despite several expected advantages, the 5.2 V intercalation process currently exhibits low first-cycle efficiencies and limited charge/discharge rates. Possible causes can be likely attributed to a poor solid-electrolyte interface (SEI) and the large anion diameters, increasing inefficiencies from long intercalation pathways. Furthermore, theoretical predictions limit cathode stage 1 intercalation to one anion per 24 carbons (compared to one cation per 6 carbons for stage 1 anode intercalation), inherently limiting the system’s energy density. To maximize capacitance and long-term cyclabilities, the carbon structure and surface chemistry of both the cathode and anode materials must be optimized for the specific electrolyte and be appropriately matched with respective properties of the opposite electrode material. To accomplish this goal, we subjected spherical, core-shell, and stacked graphite structures to 1100 – 1800 °C vacuum annealing, impact milling, 570 °C air oxidation, C2F6 plasma discharge, and high-temperature treatments using melamine and H2. These procedures defunctionalized surfaces [2], altered defects in the sp2 lattice, or selectively grafted C=O, C-F, C-Nx, and C-H groups, respectively. Following electrochemical cycling between 4.0 and 5.2 V in 2.0 m LiPF6 in fluoroethylene carbonate (FEC), ethylmethycarbonate (EMC) electrolytes and a tris(hexafluoro-iso-propyl)phosphate (HFiP) additive, we observed different effects of specific surface chemistries on anode and cathode capacities and first-cycle efficiencies. In particular, we observe positive influences of hydrogenated anode surfaces and improved performances for oxidized cathodes. Similar modifications of spherical and layered graphite electrodes yielded asymmetric efficiencies and long-duration cyclabilities, indicating divergent influences of functionalities on specific intercalated ions. Matching the appropriate surface groups for anode and cathode dual-graphite batteries, we observe improvements in coulombic efficiencies and long-term cyclabilities. Our findings offer fundamental insights into the dual-intercalation process and provide pathways for optimization of these all-carbon, environmentally friendly energy storage systems [3] for grid-level applications. 1. Read, J. A.; Cresce, A. V.; Ervin, M. H.; Xu, K., Dual-graphite chemistry enabled by a high voltage electrolyte. Energy & Environmental Science 2014, 7(2), 617-620. 2. Dyatkin, B.; Gogotsi, Y., Effects of Structural Disorder and Surface Chemistry on Electric Conductivity and Capacitance of Porous Carbon Electrodes. Faraday Discussions 2014, 172. 3. Dyatkin, B.; Presser, V.; Heon, M.; Lukatskaya, M. R.; Beidaghi, M.; Gogotsi, Y., Development of a Green Supercapacitor Composed Entirely of Environmentally Friendly Materials. ChemSusChem 2013, 6 (12), 2269–2280. Figure 1

Optimizing Capacities of Distributed Generation and Energy Storage in a Small Autonomous Power System Considering Uncertainty in Renewables

This paper explores real power generation planning, considering distributed generation resources and energy storage in a small standalone power system. On account of the Kyoto Protocol and Copenhagen Accord, wind and photovoltaic (PV) powers are considered as clean and renewable energies. In this study, a genetic algorithm (GA) was used to determine the optimal capacities of wind-turbine-generators, PV, diesel generators and energy storage in a small standalone power system. The investment costs (installation, unit and maintenance costs) of the distributed generation resources and energy storage and the cost of fuel for the diesel generators were minimized while the reliability requirement and CO2 emission limit were fulfilled. The renewable sources and loads were modeled by random variables because of their uncertainties. The equality and inequality constraints in the genetic algorithms were treated by cumulant effects and cumulative probability of random variables, respectively. The IEEE reliability data for an 8760 h load profile with a 150 kW peak load were used to demonstrate the applicability of the proposed method.

Supervisor control for stand-alone photovoltaic/hydrogen/ battery bank system to supply energy to an electric vehicle

In this paper, supervisor control for stand-alone hybrid power system to supply energy to an electric vehicle is presented. The hybrid system is used to produce energy without interruption and it consists of a photovoltaic generator (PV), a proton exchange membrane fuel cell (PEMFC) and a battery bank. PV and PEMFC systems work in parallel via DC/DC converter and the battery bank is used to store the excess of energy. The mathematical model topology, the identification of each subsystem and the control supervision of the global system are the contribution of this paper. Obtained results under Matlab/Simulink and some experimental ones are presented and discussed.

A smooth co-ordination control for a hybrid autonomous power system (HAPS) with battery energy storage (BES)

The standalone hybrid power system constitutes a synchronous generator driven by a diesel engine, renewable energy source (wind) apart from a battery energy storage system. A coherent control strategy to regulate the voltage and frequency of the standalone grid is proposed in this paper. The system is simulated using Matlab/Simulink for preliminary validation and further tested on a laboratory prototype which involves a TMS320LF2407A DSP controller to digitally implement the control strategy. The dynamic behavior of the system is perused through the direct connection of an induction machine. The control strategy is verified for step changes in load and variation in wind power.

A Family of Multiport Buck–Boost Converters Based on DC-Link-Inductors (DLIs)

A systematic method for derivation of a multiport converter (MPC) based on the dc-link inductor (DLI) concept is proposed in this paper. The MPC is generated by interconnecting multiple pulsating voltage cells (PVCs) through the DLIs. The PVCs can be input type, output type, and bidirectional type, and bidirectional MPC topologies can be harvested if all the PVCs are bidirectional type. As a result, a family of novel MPCs, including multiinput converters, multioutput converters, and bidirectional MPCs, are derived. With the proposed MPCs, step-up and step-down voltage conversion between any two of the ports can be implemented. As an example, the three-port bidirectional buck-boost (TP-B 3 ) converter is analyzed and applied to a stand-alone renewable power system for interconnection of three dc subsystems. The operation principles, pulse width modulation, and feed-back control strategies are presented and analyzed in depth. The analysis indicates that, compared to the traditional common dc-bus-based solution, bulky dc-link capacitor is eliminated and single-stage conversion between any two of the three dc-buses are achieved with the TP-B 3 converter, which is beneficial for higher efficiency, power density, and reliability. Experimental results are given to verify the feasibility and effectiveness of the developed TP-B 3 converter.

Study of the Efficiency of Hybrid Energy Storage Systems on the Basis of Electric Double Layer Capacitor and Accumulator

ABSTRACTCurrently the improvement of stand-alone PV power systems characteristics, including increase of their service life is the actual direction of ground solar power development. The analysis of stand-alone PV power systems efficiency with the use of ultra capacitors is carried out by the means of mathematical modeling. The obtained data shows that the use of ultra capacitors as additional short-term energy storage devices in stand-alone PV power systems contributes to considerable increase of storage batteries lifetime and the total system operating time.

Microcontroller Based Electrical Parameter Monitoring System of Electronic Load Controller Used in Micro Hydro Power Plant

In stand-alone micro-hydro power system, water turbine will vary in speed due to the variation of consumer load. This speed variation will cause in fluctuation in both voltage and frequency output from a generator. To solve this problem, electronic load controllers were invented and used in micro-hydro power system. The objective of this paper is to monitor the electrical parameters such as voltage, current, power and frequency of electronic load controller (ELC) by using microcontroller and liquid crystal display (LCD). It explains how to monitor and sense the above parameters and isolate between the power line and microcontroller. The voltage is sensed by using the step down transformer and voltage divider circuit. The current is measured with the help of an ACS 712 current sensor. Frequency signal is obtained by using a frequency signal converter circuit. Microcontroller 16F887 and liquid crystal display are used as the main devices to monitor the above parameters according to the values obtaining from the sensing circuits.

Modeling and simulation of stand-alone hybrid power system with fuzzy MPPT for remote load application

Modeling and simulation of stand-alone hybrid power system with fuzzy MPPT for remote load application

Harmonics and inter harmonics estimation of DFIG based standalone wind power system by parametric techniques

Abstract This paper presents application of parametric techniques (Estimation of signal parameter by rotational invariance techniques (ESPRIT), Root multiple signal classification (Root MUSIC)) for the estimation of harmonics/inter harmonics produced by wind generator under constant, variable rotor speed, load imbalance. Accuracy of estimation by parametric techniques is checked on synthetic signal as well as signal extracted from DFIG based standalone system with constant rotor speed and balanced load condition. Further sliding window concept is applied to parametric techniques to estimate the harmonics/inter harmonics under variable rotor speed and load unbalance. Series of simulation results demonstrate the advantages of the sliding window ESPRIT over sliding window Root MUSIC in the estimation of harmonics and inter harmonics under variable rotor speed as well as load unbalance condition.

Development of Software for Analyzing of Solar Irradiance and Sizing of Stand-Alone PV Power Systems

An analyzing software was developed for studying the solar irradiance on the Universidad Militar Nueva Granada (UMNG) Campus, as well as for sizing a stand-alone photovoltaic (PV) system in terms of power generation and energy storage, which is intended to be part of an hybrid DC smart grid with several energy sources, including not only solar but additional renewable. This software has a two stage sequential structure: First, it let to calculate the total solar energy resource and define the average irradiance and its variability for several user-defined periods, i.e. daily, monthly, annual and even multiannual. Simultaneously, the software gives the user a graphical data variation, where irradiance in hours of bright sunlight (at Standard Test Conditions - STC: 1 kWh/m2) and variability are organized in a period range (hours, days or months). The sizing stage let to define the system architecture in terms of modules and batteries, i.e. estimate PV network and battery bank. Finally, after providing load, voltage level and autonomy, it proceeds to calculations, considering factors of safety.