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Systems Journal, IEEE

Issue 1 • Date March 2012

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Displaying Results 1 - 25 of 28
  • [Front cover]

    Page(s): C1
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  • IEEE Systems Journal publication information

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  • Table of contents

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  • Guest Editorial: Special Issue on Integration of Intermittent Renewable Energy Resources Into Power Grid

    Page(s): 2 - 3
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    The 20 papers in this special issue cover a wide range of important issues in the emerging field, including planning and operations of power systems, hybrid generation systems, distributed generation, microgrid, wind/solar farm design and optimization, and other related topics and emerging technologies. View full abstract»

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  • Persistent Net-AMI for Microgrid Infrastructure Using Cognitive Radio on Cloud Data Centers

    Page(s): 4 - 15
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    We address the potential for a truly universal set of integrated wireless communication services, energy management, and control services for a next-generation of National Institute of Standards and Technology microgrid standards. Our approach uses cloud computing data center as the central communication and optimization infrastructure supporting a cognitive radio network of AMI meters which we label netbook advance metering infrastructure (Net-AMI). The Net-AMI is a novel low cost infrastructure of AMI meters that operate akin to netbooks with wireless transceiver that access to cloud data center energy services, cognitive radio services, and wireless communication services. Access occurs via cognitive radios channels. We claim that this solution solves the important problem in smart grid systems of how to develop an extensible, persistent, smart grid information network with a lifespan equivalent to that of most power systems (20-30 years). By persistence, we imply always operable, entirely software upgradeable, and independent of cellular networks. Our system is extensible and can easily handle thousands of variations in power systems, communication protocols, control, and energy optimization protocols. We formulate necessary link analysis and optimum scheduling of downlink and uplink Net-AMI packets in a multiuser cognitive radio environment. View full abstract»

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  • Coordinated Tuning of DFIG-Based Wind Turbines and Batteries Using Bacteria Foraging Technique for Maintaining Constant Grid Power Output

    Page(s): 16 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4383 KB) |  | HTML iconHTML  

    This paper proposes the use of battery energy storage (BES) system for the grid-connected doubly fed induction generator (DFIG). The BES would help in storing/releasing additional power in case of higher/lower wind speed to maintain constant grid power. The DC link capacitor is replaced with the BES system in a DFIG-based wind turbine to achieve the above-mentioned goal. The control scheme is modified and the co-ordinated tuning of the associated controllers to enhance the damping of the oscillatory modes is presented using bacterial foraging technique. The results from eigenvalue analysis and the time domain simulation studies are presented to elucidate the effectiveness of the BES systems in maintaining the grid stability under normal operation. View full abstract»

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  • Wind and Energy Markets: A Case Study of Texas

    Page(s): 27 - 34
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    Many jurisdictions worldwide are greatly increasing the amount of wind production, with the expectation that increasing renewables will cost-effectively reduce greenhouse emissions. This paper discusses the interaction of increasing wind, transmission constraints, renewable credits, wind and demand correlation, intermittency, carbon prices, and electricity market prices using the particular example of the Electric Reliability Council of Texas market. An estimate is made of the cost of using wind to mitigate greenhouse gas emissions. View full abstract»

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  • Integrating Load Reduction Into Wholesale Energy Market With Application to Wind Power Integration

    Page(s): 35 - 45
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    Renewable energy resources, notably wind power, are expected to provide considerable portion of the world energy requirements in the near future. Many system operators around the world are challenged by the problems associated with integrating these intermittent resources into the grid. As one of the potential solutions, demand response (DR) is expected to play a major role for mitigating integration issues of intermittent renewable energy resources. In this context, this paper proposes a DR program which helps to integrate wind power by reshaping the load of the system. The DR program provides a framework to procure load reduction from DR resources in the wholesale energy market. The participants in the program submit their offer packages to provide load reduction in the day-ahead energy market. A day-ahead network-constrained market clearing formulation is also proposed which considers the load reduction provided by the DR program participants as an energy market commodity. The proposed method, which is in the mixed-integer linear programming format, determines commitment state of generating units, schedules the energy and spinning reserve provided by generating units, and schedules the load reduction provided by the DR program participants. To reveal the features of the proposed method, several numerical studies are conducted on the IEEE-RTS. The results presented indicate that integrating load reduction in the energy market provides a powerful tool to selectively modify the system load to support wind power integration, while making significant economic and technical benefits for the system. View full abstract»

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  • Dynamic Interactions of TGC and Electricity Markets to Promote Wind Capacity Investment

    Page(s): 46 - 57
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    This paper proposes a time simulation model for long-term wind capacity investment decisions in the presence of electricity market and tradable green certificate (TGC) market. Investment decisions and wind capacity development are fundamentally based on incentives gained from both these markets. In TGC market, the tradable certificates are issued to renewable generation companies for each megawatt-hour of electricity generation. Distribution companies are obligated to support fraction of their electricity consumptions from renewable sources. The dynamics of prices in both markets are simulated in a system dynamics model to trace the dynamics of wind capacity investment. Such a decision model enables both the wind generation investors and the regulators to gain perfect insight into finding possible consequences of different decisions that they should make under different policies and markets conditions particularly in the preliminary design of TGC market. The impacts of regulatory policies, trading strategies of players, and uncertainties in both markets are examined in a case study. View full abstract»

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  • Centralized and Distributed Active and Reactive Power Control of a Utility Connected Microgrid Using IEC61850

    Page(s): 58 - 67
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    This paper describes the control algorithm of a utility connected microgrid, based on independent control of active and reactive power and operating in centralized and distributed operation mode. The microgrid is composed of several (three in the experimental tests conducted) configurable units, including generation, storage, and load units. These units are interfaced with the microgrid through a voltage source converter and are controlled by the nodes of the communication system by means of IEC 61850. The proposed control strategy is validated by simulation in MATLAB/Simulink and with experimental tests. View full abstract»

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  • A Flexible DG Interface Based on a New RLS Algorithm for Power Quality Improvement

    Page(s): 68 - 75
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    Distributed generation (DG) exists in distribution systems and is installed by either the utility or the customers. This paper proposes a novel utilization of the existing DG interface to not only control the active power flow, but also to mitigate unbalance, harmonics and voltage flicker, and manage the reactive power of the system. The proposed flexible distributed generation (FDG) is similar in functionality to FACTS, but works at the distribution level. Moreover, a novel recursive least square (RLS) structure is presented. The new structure is applied to multi-output (MO) systems for parameter tracking/estimation, and is called MO-RLS. It is dedicated to symmetrical components estimation. An innovative processing unit-based RLS is investigated to deal with unbalance, harmonics, and reactive power compensation. In addition, this paper portrays a technique for flicker mitigation based on the RLS algorithm for instantaneous tracking of the measured voltage envelope. One advantage of the proposed control system is its insensitivity to parameter variation, a necessity for distribution system applications. Simulations of the suggested FDG based control algorithm are conducted to evaluate the performance of the proposed system. View full abstract»

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  • Investigation of the Impacts of Large-Scale Wind Power Penetration on the Angle and Voltage Stability of Power Systems

    Page(s): 76 - 84
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    The complexity of power systems has increased in recent years due to the operation of existing transmission lines closer to their limits, using flexible AC transmission system (FACTS) devices, and also due to the increased penetration of new types of generators that have more intermittent characteristics and lower inertial response, such as wind generators. This changing nature of a power system has considerable effect on its dynamic behaviors resulting in power swings, dynamic interactions between different power system devices, and less synchronized coupling. This paper presents some analyses of this changing nature of power systems and their dynamic behaviors to identify critical issues that limit the large-scale integration of wind generators and FACTS devices. In addition, this paper addresses some general concerns toward high compensations in different grid topologies. The studies in this paper are conducted on the New England and New York power system model under both small and large disturbances. From the analyses, it can be concluded that high compensation can reduce the security limits under certain operating conditions, and the modes related to operating slip and shaft stiffness are critical as they may limit the large-scale integration of wind generation. View full abstract»

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  • A Feedback Linearization Control Scheme for the Integration of Wind Energy Conversion Systems Into Distribution Grids

    Page(s): 85 - 93
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    This paper focuses on the development of a control strategy for integration of wind energy conversion systems (WECS) into the electrical distribution networks with particular attention to the combined provision of energy and ancillary services. Typically, a WECS is composed by a variable speed wind turbine coupled with a direct driven permanent magnet (DDPM) synchronous generator. This configuration offers a considerable flexibility in design and operation of the power unit, as its output is delivered to the grid through a fully controlled frequency converter. Here, a new control scheme to regulate electrical and mechanical quantities of such generation unit is proposed, aimed both at reaching optimal performances in terms of power delivered to the grid and at providing the voltage support ancillary service at the point of common coupling. The control scheme is derived resorting to the feedback linearization (FBL) technique, which allows both decoupling and linearization of a non linear multiple input multiple output system. Several numerical simulations are then performed in order to show how the flexibility of the DDPM wind generator can be fully exploited, thanks to the use of the FBL approach, which assures independent control of each variable and significant simplifications in controller synthesis and system operation, thus making it easier to integrate WECS into modern day smart grids. View full abstract»

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  • Optimization of Wind Farm Turbine Layout Including Decision Making Under Risk

    Page(s): 94 - 102
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    This paper presents a new contribution to optimal wind farm design, including the main risk management aspects. The objective of the algorithm is to optimize the expected profits of the wind farm by taking into account that the wind data used to design the wind farm involves some degree of uncertainty that affects the final return of the project. Net present value (NPV) will be used as a figure of the profitability in the proposed method. The maximization of the NPV means the maximization of the cumulative net cash flows (by maximizing the generation of net energy) and minimization of the investment. Both terms mainly depend on the number and type of wind turbines, tower height, and geographical position, among other factors. Therefore, the tool developed in this paper is intended to determine the wind farm configuration most suitable in the presence of risk due to uncertainty in the wind data. View full abstract»

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  • Resource Scheduling Under Uncertainty in a Smart Grid With Renewables and Plug-in Vehicles

    Page(s): 103 - 109
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    The power system and transportation sector are our planet's main sources of greenhouse gas emissions. Renewable energy sources (RESs), mainly wind and solar, can reduce emissions from the electric energy sector; however, they are very intermittent. Likewise, next generation plug-in vehicles, which include plug-in hybrid electric vehicles and electric vehicles with vehicle-to-grid capability, referred to as gridable vehicles (GVs) by the authors, can reduce emissions from the transportation sector. GVs can be used as loads, energy sources (small portable power plants) and energy storage units in a smart grid integrated with renewable energy sources. However, uncertainty surrounds the controllability of GVs. Forecasted load is used in unit commitment (UC); however, the actual load usually differs from the forecasted one. Thus, UC with plug-in vehicles under uncertainty in a smart grid is very complex considering smart charging and discharging to and from various energy sources and loads to reduce both cost and emissions. A set of valid scenarios is considered for the uncertainties of wind and solar energy sources, load and GVs. In this paper, an optimization algorithm is used to minimize the expected cost and emissions of the UC schedule for the set of scenarios. Results are presented indicating that the smart grid has the potential to maximally utilize RESs and GVs to reduce cost and emissions from the power system and transportation sector. View full abstract»

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  • Impact of Distributed Generations With Energy Storage Devices on the Electric Grid

    Page(s): 110 - 117
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    The commonly used distributed generations (DG) technologies include wind generators, photovoltaics, and biomass generators with their sizes varying between several kW to a few MW. Energy storage devices are generally used to smooth variations in DG's MW output due to inherent unpredictability and to minimize exchange of power from grid. Connecting the storage and DGs to the grid have both technical and economic impacts. This paper aims at analyzing the technical and economic impacts of distributed generators along with energy storage devices on the distribution system. The technical analysis includes analyzing the transient stability of a system with DGs and energy storage devices, such as a battery and ultracapacitor. The DGs are represented by small synchronous and induction generators. Different types and locations of faults and different penetration levels of the DGs are considered in the analysis. Energy storage devices are found to have a positive impact on transient stability. For economic analysis, the costs of the system with different DG technologies and energy storage devices are compared using the software tool “hybrid optimization model for electric renewables (HOMER).” Finally, the analysis for cost versus benefits of DGs and energy storage devices is compared briefly. View full abstract»

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  • Micro Wind Power Generator With Battery Energy Storage for Critical Load

    Page(s): 118 - 125
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    In the micro-grid network, it is especially difficult to support the critical load without uninterrupted power supply. The proposed micro-wind energy conversion system with battery energy storage is used to exchange the controllable real and reactive power in the grid and to maintain the power quality norms as per International Electro-Technical Commission IEC-61400-21 at the point of common coupling. The generated micro-wind power can be extracted under varying wind speed and can be stored in the batteries at low power demand hours. In this scheme, inverter control is executed with hysteresis current control mode to achieve the faster dynamic switchover for the support of critical load. The combination of battery storage with micro-wind energy generation system (μ WEGS), which will synthesize the output waveform by injecting or absorbing reactive power and enable the real power flow required by the load. The system reduces the burden on the conventional source and utilizes μ WEGS and battery storage power under critical load constraints. The system provides rapid response to support the critical loads. The scheme can also be operated as a stand-alone system in case of grid failure like a uninterrupted power supply. The system is simulated in MATLAB/SIMULINK and results are presented. View full abstract»

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  • Optimal Control in a Cooperative Network of Smart Power Grids

    Page(s): 126 - 133
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    The possibility to store energy, to exchange power and information on demand and production among grids allows us to achieve an active distribution which is of major interest for cooperative smart power grids, that are grids which can forecast demand and production and are able to exchange power in order to enhance the quality of the service. In this paper, a model to support optimal decisions in a network of cooperative grids is formalized as an original discrete and centralized problem here defined as cooperative network of smart power grids (CNSPG) problem. In the CNSPG problem, the control variables are the instantaneous flows of power in the network of grids, which can be obtained from the solution of a linear quadratic Gaussian problem on a fixed time horizon. A simple case study showing the enhancement which may be obtained from the introduction of direct connections among microgrids according to a lattice network is shown and finally discussed. View full abstract»

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  • Impact Analysis of Wind Farms in the Jeju Island Power System

    Page(s): 134 - 139
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    This paper presents modeling and impact analysis of wind farms in Jeju island power system, which is made of wind farms, a current source-type high-voltage, direct current (HVDC) system, and thermal power plants. In this paper, four kinds of major components are modeled: a total of 88 MW wind farms, a 300 MW HVDC system, thermal power plants, and the Jeju power system load. To analyze the impact of the wind power generation to the Jeju power system, simulation is carried out for two case studies by using the PSCAD/EMTDC program. One is for the steady-state operation under different wind speed, and the other is for the transient-state operation when all wind farms are disconnected suddenly from the Jeju power grid due to the wind speed higher than the rated value. These comparative studies have been effective in accessing the impact of wind power generation on the Jeju island power system stability. View full abstract»

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  • Unified System-Level Modeling of Intermittent Renewable Energy Sources and Energy Storage for Power System Operation

    Page(s): 140 - 151
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    The system-level consideration of intermittent renewable energy sources (RES) and small-scale energy storage in power systems remains a challenge as either type is incompatible with traditional operation concepts. Noncontrollability and energy constraints are still considered contingent cases in market-based operation. The design of operation strategies for up to 100% RES power systems requires an explicit consideration of nondispatchable generation and storage capacities, as well as the evaluation of operational performance in terms of energy efficiency, reliability, environmental impact, and cost. By abstracting from technology-dependent and physical unit properties, the power nodes modeling framework presented here allows the representation of a technologically diverse unit portfolio with a unified approach, while establishing the feasibility of energy-storage consideration in power system operation. After introducing the modeling approach, a case study is presented for illustration. View full abstract»

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  • Performance Assessment of Micro and Small-Scale Wind Turbines in Urban Areas

    Page(s): 152 - 163
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    This paper addresses some general issues related to the difficulties and uncertainties during the assessment and characterization of micro and small-scale wind-based generation in urban areas. This paper proposes four generic wind turbine models, which could be used for the analysis and selection of optimal wind turbines in target applications, as they accurately represent the range of wind turbines currently available on the market. The analysis in this paper compares results for the expected annual energy outputs and cost-benefit analysis obtained using steady state and dynamic wind turbine models of actual and generic micro/small wind turbines, applying both low-resolution and high-resolution measurements of available wind energy resources. The presented results demonstrate the significance of the accurate assessment of wind resources in urban areas, as well as the importance of the correct modeling of wind turbine characteristics. It is shown that substantial errors, typically overestimating wind turbine performance, are obtained if standard assumptions and current recommendations are used for the analysis of wind turbine performance. View full abstract»

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  • Optimal Electric Network Design for a Large Offshore Wind Farm Based on a Modified Genetic Algorithm Approach

    Page(s): 164 - 172
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    The increasing development of large-scale offshore wind farms around the world has caused many new technical and economic challenges to emerge. The capital cost of the electrical network that supports a large offshore wind farm constitutes a significant proportion of the total cost of the wind farm. Thus, finding the optimal design of this electrical network is an important task, a task that is addressed in this paper. A cost model has been developed that includes a more realistic treatment of the cost of transformers, transformer substations, and cables. These improvements make this cost model more detailed than others that are currently in use. A novel solution algorithm is used. This algorithm is based on an improved genetic algorithm and includes a specific algorithm that considers different cable cross sections when designing the radial arrays. The proposed approach is tested with a large offshore wind farm; this testing has shown that the proposed algorithm produces valid optimal electrical network designs. View full abstract»

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  • Fuzzy Logic-Based Load-Frequency Control Concerning High Penetration of Wind Turbines

    Page(s): 173 - 180
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    Load-frequency control (LFC) in interconnected power systems is undergoing fundamental changes due to rapidly growing amount of wind turbines, and emerging of new types of power generation/consumption technologies. The infrastructure of modern LFC systems should be able to handle complex multiobjective regulation optimization problems characterized by a high degree of diversification in policies, and widely distribution in demand and supply sources to ensure that the LFC systems are capable to maintain generation-load balance, following serious disturbances. Wind power fluctuations impose additional power imbalance to the power system and cause frequency deviation from the nominal value. This paper addresses a new decentralized fuzzy logic-based LFC schemes for simultaneous minimization of system frequency deviation and tie-line power changes, which is required for successful operation of interconnected power systems in the presence of high-penetration wind power. In order to obtain an optimal performance, the particle swarm optimization technique is used to determine membership functions parameters. The physical and engineering aspects have been fully considered, and to demonstrate effectiveness of the proposed control scheme, a time domain simulation is performed on the standard 39-bus test system. The results are compared with conventional LFC design for serious load disturbance and various rates of wind power penetrations. View full abstract»

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  • Probabilistic Assessment of TTC in Power Systems Including Wind Power Generation

    Page(s): 181 - 190
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    Wind farms (WFs) are now being used for electric power generation in some parts of the world and their penetration is expected to increase significantly. With increasing penetration of WFs in electric power systems, modification of current tools for evaluating and managing the system is an important issue. Determination of total transfer capability (TTC) is one such tool and is of considerable importance in the restructured power systems. TTC is used to calculate maximum power that can be transferred between areas in a reliable manner and schedule future transactions and commercial activities. In this paper, a method is proposed for TTC evaluation in the presence of WFs. In the proposed approach, Monte Carlo method is used to simulate a system state and optimal power flow is used to calculate the TTC level for each state. Risk analysis is used as a decision-making tool to determine the appropriate TTC level. IEEE reliability test system is used to demonstrate the effectiveness of the proposed approach. View full abstract»

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  • IEEE Foundation [advertisement]

    Page(s): 191
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Aims & Scope

The IEEE Systems Journal is created to provide a systems-level focused forum for application-oriented manuscripts that address complex systems and system-of-systems of national and global significance

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Professor Vincenzo Piuri
Università degli Studi di Milano