With the advancement of process technology for fabrication of integrated circuits, the magnitude of variations in process parameters have increased and the parametric yield loss problem has become a serious concern of the fabrication houses. Thus, the traditional techniques for power and delay optimization in design automation tools can no longer be used effectively. This has opened up a challenge to the chip designers to design integrated circuits, which are variation tolerant and thereby having higher parametric yield. In this monograph, a single threshold voltage based approach is proposed that exhibits runtime leakage power reduction comparable to the existing dual threshold voltage assignment approaches and at the same time the proposed approach is less sensitive to process parameter variations. Again, this logic-level runtime leakage reduction technique is combined with multiple supply voltage assignment during high-level synthesis for total power reduction. It is believed that the proposed leakage power reduction technique will be useful in digital circuit design flow (logic-level and high-level syntheses) under process parameter variation.
In the next years, several offshore wind farms will be installed all over Europe. Due to the technologic advantages that voltage-source converters have when compared to other available options, there is a strong possibility that this will be the technology chosen to connect offshore wind farms. Such assumption intensifies the need of studying and simulating the control methods for these systems. Therefore, the purpose of this work is to present and explain all the models that are needed to simulate, with the necessary detail, the electric systems of the offshore wind farms, the high-voltage converters and the DC grid. The control method of the DC system is given and several methods to control the DC grid voltage are presented and compared. This way, it will be possible for several countries connected to the multi-terminal DC grid not only to receive energy from the offshore wind farms, according to desired criteria, but also to trade energy with other nations.
A comprehensive study is made to compare the harmonic distortion produced by the different types and number of distributed generation (DG) units in a low voltage distribution system. Here, three types of DG units are considered, namely, a mini hydro power, wind turbine doubly fed induction generator and photovoltaic system. To determine the maximum allowable penetration level of inverter based DG, harmonic resonance phenomena and harmonic distortion limits are also considered. To control harmonic propagation in a distribution system with DG units, an appropriate planning of DG units is considered by determining optimal placement, sizing and voltage control of DG units. Thus, an effective heuristic optimisation technique such as improved gravitational search algorithm (IGSA) technique is also developed for determining the optimal placement, sizing and voltage control of DG units in a radial distribution system.
Irrational using of natural resources, depletion of natural resource, pollution are the main problems of this time - and these problems are not of one person, but of the whole humanity. People by their houghtless actions destroy nature, forgetting that this is not forever. It also pollutes the environment and thus causes irreversible consequences. Each person must think about tomorrow and try to keep what he has. And so the researching of environmental problems is one of the important task of the present time.
Optimal reactive power and voltage control for distribution system involves the installation of fixed shunt capacitors and tap changing voltage regulators along distribution feeders. This can improve voltage profiles for all end-use customers and reduce real power losses. In this book, the fuzzy logic optimization technique is studied and applied to solve the capacitor allocation problem in radial distribution systems. Using voltage regulator for voltage control of radial distribution systems is also studied to allow more loss reduction and to improve the whole system voltage profile. The applicability of the fuzzy logic technique in the field of capacitor placement problem is discussed. Modifications are made to existing fuzzy membership functions to obtain better results. Also, an approach using tap-changing voltage regulators is applied to maintain the voltage profile on a general radial distribution system within a pre-specified bandwidth. In addition, the action of the regulators is studied to provide the best possible profile while maximally decreasing system losses; this is done by controlling the regulator tap positions.
Increasing negative effects of fossil fuel combustion on the environment in addition to its limited stock have forced many countries to explore and change to environmentally friendly alternatives that are renewable to sustain the increasing energy demand.Wind is a free,clean and inexhaustible energy source.In this study,statistical analyses of the wind speed data for 23 meteorological stations located at various topographic locations in Iraqi Kurdistan Region, for periods from 1967 to 2007, have been carried out and assessed.The wind data at height 45 m were obtained by extrapolation of the data at 10 m height using the power law formula.The wind energy potential of the site is also statistically analyzed which is based on wind speed data. This study describes the influence of simple and complex terrain on the wind field.The Weibull function is used for representing wind speed frequency distribution.The wind potential energy of the region was statistically analyzed and based on mean annual time-series wind speed.The wind source in the Iraqi Kurdistan Region is classified using the standard scheme which was proposed by other studies.
Power quality is one of the major concerns in the present era. The problem of voltage sags and swells and its major impact on sensitive loads are well known. To solve this problem, custom power devices are used. One of those devices is the Dynamic Voltage Restorer (DVR), which is one of the most efficient and effective modern custom power devices used in power distribution networks. A new control algorithm for the DVR is proposed in this paper to regulate the load terminal voltage during sag, swell in the voltage at the point of common coupling (PCC). This new control algorithm is based on synchronous reference frame theory (SRF) along with PI controller is used for the generation of reference voltages for a dynamic voltage restorer (DVR). These voltages, when injected in series with a distribution feeder by a voltage source inverter (VSI) with PWM control, can regulate the voltage at the load terminals against any power quality problem in the source side. It first analyzes the power circuit of the system in order to come up with appropriate control limitations and control targets for the compensation voltage control through the DVR.
The greatest contribution to researchers, who are working on renewable power generation sources especially on wind energy systems. The author explores different type of power electronic interfaces connected to isolated loads or grid. The book gives complete idea about the different approaches for steady-state analysis of self excited induction generator. The book must read for basic concepts and detail understanding about the possible power electronic interfaces in wind energy systems.
My book is about the protection and control in the CIGRE low voltage distribution grid and the networks like this in case of large scale renewable energy integration. As the stochastic nature wind and solar power creates problems of voltage and power oscillations in the main grid and also RE integration presents problems in the protection of the networks. Some of these problems have been solved in this book. Also the mitigation of the balanced and unbalanced voltage sags have been presented in this book. The issues of the islanding and reconnection have also been discussed here and the constancy of the voltage and the frequency in the islanded Micro Grid (MG) has also been maintained by using STATCOM controllers
In this study the emphasis is placed on renewable energy sources with reference to the energy derived from the wind. The advantages and disadvantages of wind energy exploitation are presented here. In order to exploit the energy from the wind, wind power plants are required which consist of one or more wind turbines to produce energy. The district of Bjelovar-Bilogora Country was explored for the purposes of selecting the best location for a small wind power plant project. The AHP - Analytic Hierarchy Process - method was used to select the best location for the installation of the small wind power plant. It is based on a mathematical model and is used in choosing among multiple alternatives and delivers flexibility in decision making. The risks that may occur during the construction of the small wind power plant are also presented. There are many of them, as in every project, but they must be taken very seriously in order to complete the project successfully.
Voltage controlled oscillator characterize unique materials for investigation the phenomena at the nanoscale. Different types of oscillator are described in the main text and for that voltage controlled oscillator leakage reduction is also necessary for perfect performance of circuit. So different power reduction techniques are applied on the main circuit. In this book first section describes the basic introduction of oscillator and second section explain the sub circuits and application of voltage controlled oscillator and third and fourth section describe the power reduction technique applied on the voltage controlled oscillator and comparative study is provided with excellent performance of VCO
Circuit designers perform optimization procedures targeting speed and power. Gate sizing can be applied to optimize for speed, while Dual-VT and Dynamic Voltage Scaling (DVS) can be applied to optimize for leakage and dynamic power, respectively. Both gate sizing and Dual-VT are design-time techniques applied to the circuit at a fixed voltage. DVS is a run-time technique and implies that the circuit will be operating at a different voltage than that used during optimization at design-time. After some analysis, the risk of non-critical paths becoming critical paths at run-time is detected under these circumstances. The following questions arise: 1) should we take DVS into account during optimization? 2) Does DVS impose any restrictions to design-time circuit optimizations? This is a case study of applying DVS to a circuit that has been optimized for speed and power, and aims at answering the previous two questions. We used a 45-nm CMOS design kit and flow for ISCAS’85 c432. Results showed that we should not optimize using Dual-VT at an arbitrary voltage but at the lowest in the DVS range, otherwise non-critical paths might become critical paths at run-time.
This book investigate the impact of integrating a high penetration of wind power into Bahrain's power system. The power system was modeled and analyzed before and after wind integration covering different wind penetration level. In order to mitigate against the possible impact of high levels of wind power, the operation of reverse osmosis stations was modeled as a means of providing additional grid balancing.
Renewable energy is an important item on the European Union’s agenda. The current goal is to increase the share of renewable energy in the EU energy mix to 20% by 2020, currently being 13%. Wind power will play a big role in achieving this goal. This work focuses on the wind power sector in Germany, one of the European leaders in the expansion of this renewable energy source. Since renewable energy in Germany is supported by the feed-in tariff, this puts tens of billions of euros at stake. This work presents a cost benefit analysis of the whole industry until 2030, separately for onshore and offshore installations. Various costs and benefits stemming from the expansion of wind power are inferred from literature review and studying the peculiarities of the German case. The magnitude of governmental support is calculated by applying the Weibull distribution of wind speeds at different zones across Germany and power curves of 5 modern wind turbines. The analysis performed in this work may be useful for political decision makers wishing to approach wind power in a balanced way. Researchers might use the Weibull and Power Curve framework discussed in this research in their own work.
Natural resources are destroyed rapidly. The energy is an important issue for the protection of natural resources. Landscape architectures do landscape planning for protection nature. Concepts of nature conservation and energy are related. Therefore, wind energy has been one of the most important issues of the world market recently.The study contain that current status of wind energy according to countries, determination of eligibility criteria for wind energy in case area and Where is the suitable for wind energy in case area.