Robust LPV control of diesel auxiliary power unit for series hybrid electric vehicles

This paper presents a robust gain-scheduling approach for the control of diesel auxiliary power unit (APU) for series hybrid electric vehicles (SHEVs), using the linear parameter-varying (LPV) techniques. An average physical model of the diesel APU is established, which combines the subsystem models including diesel engine, synchronous generator, and three-phase diode rectifier in an elegant way. The nonlinear system model is then formulated as a quasi-LPV form with parametric uncertainty and augmented with performance objectives in a robust control framework. As a solution to this type of control problem, a robust LPV control synthesis method is proposed and its numerical implementation issues are also considered. Simulation results verify the performance of the proposed robust LPV controller.     

Experimental 6-GHz frozen wave generator with fiber-optic feed

Experimental results from an optically activated 6 GHz frozen wave generator (FWG) test device are presented. The several system components needed to produce a low-cost monolithic pulsed power source suitable for large phased arrays are demonstrated. Static electric energy stored in 50 ohm microstrip transmission lines is released by fast GaAs photoconductive (PC) switches activated by 50 picosecond laser pulses distributed over fiber-optics. The present device is of hybrid construction, using commercial fiber-optic pigtailed integrated optic couplers and semi-insulating (SI) GaAs metal-semiconductor-metal (MSM) photoconductive switch chips bonded into microstrip. However, exclusive of the laser, the design lends itself to monolithic microwave and integrated optic techniques especially at high frequencies. Experimental test results compare well with circuit simulation predictions, showing that hybrid techniques introduce negligible parasitics at the design frequency. Lower resistance PC switches are needed to fully demonstrate the high power performance capabilities of this type of device     

A Secondary Voltage Control Strategy for Transmission Level Interconnection of Wind Generation

This paper addresses implementation issues associated with secondary voltage control in a doubly-fed induction generator based wind farm. The effects of different system parameters on the performance of the control are considered, namely the short circuit ratio of the interconnection and the inherent communication delay between the wind park and the remote bus. In addition, a strategy for allocation reactive power requirements to each of the generators within the wind park is proposed. The system is developed and simulated for a wind park consisting of six wind generators connected to a typical transmission system. The paper proposes an optimal tracking secondary voltage control method developed to achieve effective voltage regulation, enhance the network voltage profile and provide optimal reactive power compensation to the interconnected power system. The performance of the controller is compared with secondary voltage control at one selected bus, primary voltage control and the optimal voltage profile obtained from the optimal power flow analysis. The performance of the controllers is tested for steady state operation and in response to system contingencies, taking into account the impact of communication time delays and short circuit ratio (SCRs). Simulation results are presented to demonstrate the capability of the controllers to provide the desired reactive power compensation and voltage support to the electric power grid.     

Sizing and Energy Management of a Hybrid Locomotive Based on Flywheel and Accumulators

The French National Railways Company (SNCF) is interested in the design of a hybrid locomotive based on various storage devices (accumulator, flywheel, and ultracapacitor) and fed by a diesel generator. This paper particularly deals with the integration of a flywheel device as a storage element with a reduced-power diesel generator and accumulators on the hybrid locomotive. First, a power flow model of energy-storage elements (flywheel and accumulator) is developed to achieve the design of the whole traction system. Then, two energy-management strategies based on a frequency approach are proposed. The first strategy led us to a bad exploitation of the flywheel, whereas the second strategy provides an optimal sizing of the storage device. Finally, a comparative study of the proposed structure with a flywheel and the existing structure of the locomotive (diesel generator, accumulators, and ultracapacitors) is presented.     

Error performance of hybrid wireless-power line communication system

This paper considers a hybrid wireless-power line communication system for smart meter and grid interaction. The performance of the considered system is evaluated for different switching schemes such as threshold based switching, random switching, and selection combining. The power line channel is characterized using the log-normal random variable, whereas the channel response for the wireless link is modeled as the Nakagami-m distributed random variable. The expressions for average bit-error-rate (BER) for the considered switching/combining schemes are obtained, and the average BER performances of all the considered combining schemes are compared. The results are verified through simulations.     

Energy Management for a Residential Microgrid Using Wavelet Transform and Fuzzy Control Including a Vehicle-to-Grid System

This paper presents the design and implementation of an energy management system (EMS) with wavelet transform and fuzzy control for a residential micro-grid. The hybrid system in this paper consists of a wind turbine generator, photovoltaic (PV) panels, an electric vehicle (EV), and a super capacitor (SC), which is able to connect or disconnect to the main grid. The control strategy is responsible for compensating the difference between the generated power by the wind and solar generators and the demanded power by the loads. Wavelet transform decomposes the power difference into a smoothed component and a fast fluctuated component. The command approach used for fuzzy logic rules considers the state of charging (SOC) of EV, renewable production, and the load demand as parameters. Furthermore, the command rules are developed in order to ensure a reliable grid when taking into account the EV battery protection to decide the output power of the EV. The model of the hybrid system is developed in detail under Matlab/Simulink software environment.     

Control of High-Speed Solid-Rotor Synchronous Reluctance Motor/Generator for Flywheel-Based Uninterruptible Power Supplies

A hybrid controller, consisting of a model-based feedforward controller and a proportional–integral feedback compensator, for a solid-rotor synchronous reluctance motor/generator in a high-speed flywheel-based uninterruptible power supply application is proposed in this paper. The feedforward controller takes most of the control output of the current regulator based on the machine model, and the PI controllers compensate the possible inaccuracies of the model to improve the performance and robustness of the complete control system. The machine current tracking error caused by parameter inaccuracy in the model-based controller is mathematically analyzed and utilized to dynamically compensate the estimated flux linkage to eliminate the steady-state error in current regulation. Stability analysis is also presented, and it can be seen that the regulation performance and robustness of the system are improved by the proposed hybrid controller. Simulation and experimental results consisting of a flywheel energy storage system validates the performance of the controller.      

Development of a mathematical model for optimizing the design of an automotive thermoelectric generator taking into account the influence of its hydraulic resistance on the engine power

A complex of models for optimizing the design and operation modes of an automotive thermoelectric generator is developed within the proposed approach taking into account the influence of hydraulic resistance of the generator on the internal combustion engine. Several designs of generators for converting the thermal energy of exhaust gases (EGs) of internal combustion engines into electricity due to the Seebeck effect in semiconductor elements, which have different geometries of the continuous-flow part of the generator with different hydraulic resistances, are considered. Models for calculating the thermoelectric elements, gas heat exchanger, and automotive engine are considered jointly. Simulation is performed using the example of a VAZ-21126 engine, which demonstrated that up to 500 W of electric power can be obtained using semiconductor thermoelectric elements based on germanium and lead tellurides.     

Internet of Things (IOT) Based Generous Transformational Optimization Algorithm (GTOA) for Hybrid Renewable Energy System Synchronization and Status Monitioring

The Internet of Things (IoT) is the all-around trusted technology that associates natural objects to the web for giving straightforwardness and different functionalities and the hybrid power system has characterized as the power grid incorporated with an extensive network. With the change in innovation and developments needs to tackle the energy crises by utilizing hybrid renewable energy resources. The failure of electrical power in remote territories drives associations to investigate elective arrangements, for example, renewable energy power systems. The energy created by hybrid renewable energy sources are dependent on the variation and load demand, such a renewable power system must be equipped for fulfilling the necessities whenever and store the extra power for usage in deficiency situations. An independent renewable energy network to meet the coveted electric load with some sources, little excess power and minimal cost of energy. The essential goal of the design criteria is to limit the entire cost which incorporates initial, operational and support cost. In this work life-cycle cost (LCC), loss of load probability (LOLP) and loss of power supply probability (LPSP) have considered as the genuine factors and a Generous Transformational Optimization Algorithm (GTOA) has projected to pick the greatest possible configuration of a hybrid power framework. Internet of Things (IoT) conveyed in crossover control framework and gave a valuable proposition about assorted advances and norms of a renewable power source, and it additionally gives a review of a few applications and driving variables of a hybrid control framework. Simulation work done with MATLAB software and result helps the efficiency of the proposed technique and confirm that it is 97% efficiency than other ordinary strategies.     

基于双转子发电机的风光互补发电系统优化策略研究

本文为了研究提高风光互补发电系统的效率,引入了双转子发电机结构,有效提高了发电效率和电力输出的稳定性。以期为国内风光混合发电系统优化问题的合理解决提供参考。     

Performance characteristics of cellular systems with different link adaptation strategies

In this paper, the theoretical performance of cellular systems with different types of link adaptation is analyzed. A general link and system performance analysis framework is developed to enable the system-level performance characteristics of the various link adaptation strategies to be studied and compared. More specifically, this framework is used to compare the downlink performance of fully loaded cellular systems with fixed power and modulation/coding, adaptive modulation/coding (AMC), adaptive power allocation (APA) with system-level AMC, and water-filling (WF). Performance is studied first for idealized methods, and then for cases where some practical constraints are imposed. Finally, a hybrid link adaptation scheme is introduced and studied. The hybrid scheme is shown to overcome most of the performance loss caused by the practical constraints. Moreover, the hybrid scheme, as opposed to WF, enables the system to be tuned to meet the most important performance objective for the system under consideration, such as coverage reliability, capacity, or data rate distribution. The algorithms and the framework presented in this paper can be used to improve the link adaptation performance of modern cellular systems such as HSDPA.     

Hybrid Simulation of ±500 kV HVDC Power Transmission Project Based on Advanced Digital Power System Simulator

In order to effectively imitate the dynamic operation characteristics of the HVDC (high voltage direct current) power transmission system at a real 500 kV HVDC transmission project, the electro-mechanical-electromagnetic transient hybrid simulation was carried out based on advanced digital power system simulator (ADPSS). In the simulation analysis, the built hybrid model's dynamic response outputs under three different fault conditions are considered, and by comparing with the selected fault recording waveforms, the validities of the simulation waveforms are estimated qualitatively. It can be ascertained that the hybrid simulation model has the ability to describe the HVDC system's dynamic change trends well under some special fault conditions.     

Improving passive filter compensation performance with active techniques

This paper presents the performance analysis of a hybrid filter composed of passive and active filters connected in series. The analysis is done by evaluating the influence of passive filter parameters variations and the effects that different active power filter's gain have in the compensation performance of the hybrid scheme. The compensation performance is quantified by evaluating the attenuation factor in a power distribution system energizing high-power nonlinear loads compensated with passive filters and then improved with the connection of a series active power filter. Finally, compensation characteristics of the hybrid topology are tested on a 10-kVA experimental setup.     

A MEMS-based piezoelectric power generator array for vibration energy harvesting

Piezoelectric power generator made by microelectromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed MEMS power generators are featured with fixed/narrow operation frequency and power output in microwatt level, whereas, the frequency of ambient vibration is floating in some range, and power output is insufficient. In this paper, a power generator array based on thick-film piezoelectric cantilevers is investigated to improve frequency flexibility and power output. Piezoelectric cantilevers array has been designed and fabricated. The cantilevers array can be tuned to the frequency and expanded the excited frequency bandwidth in ambient low frequency vibration. Serial connection among cantilevers of the array is investigated. The prototype generator has a measured performance of 3.98 μW effective electrical power and 3.93 DC output voltage to resistance load. This device is promising to support networks of ultra-low-power, peer-to-peer, wireless nodes.     

Optimization studies on open-cycle MHD generators

An optimization theory is developed which predicts the variation of thermodynamic properties, duct shape, and electrical loading along an MHD generator for minimum duct length, duct surface area, or duct volume. The model is based on the one-dimensional flow equations including heat transfer and friction, and the analysis is developed for a fluid with arbitrary dependence of density, enthalpy, electrical conductivity, and mobility on temperature and pressure. Four types of electrical loading of the generator are considered: the segmented-electrode Faraday generators; and the cross-connected generator, first with constant cross-connection angle and multiple load connections; then with a single load; and finally with constant cross-connection angle and with single load. This theory is then applied to the design of an open-cycle MHD generator for a 2000-MW power plant. Numerical results for these four different types of generator are calculated with a computer program and compared, with particular emphasis on the loading parameter variation. It is concluded that the additional constraints of constant cross-connection angle and single load do not significantly affect the overall generator performance, although they do modify the parameter variation along the duct.     

Output Power Smoothing and Hydrogen Production by Using Variable Speed Wind Generators

This paper presents a combination system of wind energy conversion and hydrogen production. Hydrogen is expected as an alternative energy source in the future, and this is the best way to produce it from renewable energy like wind energy. On the other hand, the output of a wind generator, in general, fluctuates greatly due to wind speed variations, and thus the output fluctuations can have a serious influence on the power system operation. In the proposed system, a variable speed wind generator is adopted, and an electrolyzer is installed in parallel with it for hydrogen production. Output power from the wind generator is smoothed and supplied to the power system as well as to the electrolyzer based on the cooperative control method. The performance of the proposed system is evaluated by simulation analyses, in which simulations are performed by using PSCAD/EMTDC.      

Evaluation of Power Conditioning Architectures for Energy Production Enhancement in Thermoelectric Generator Systems

A large-scale thermoelectric generator (TEG) system has an unbalanced temperature distribution among the TEG modules, which leads to power mismatch among the modules and decreases the power output of the TEG system. To maximize the power output and minimize the power conversion loss, a centralized–distributed hybrid power conditioning architecture is presented, analyzed, and evaluated for a TEG system. The novel architecture is a combination of a conventional centralized architecture and a fully distributed architecture. By using the proposed architecture, most of the harvested power is processed by the centralized stage while only the mismatched power among the TEG modules is processed by the distributed stages. As a result, accurate and distributed maximum-power-point tracking (MPPT) for each TEG module and single-stage power conversion between the modules and load can be achieved. It offers the benefit of implementing high MPPT efficiency and high conversion efficiency simultaneously. A 50-W TEG system composed of two TEG modules is built and tested. Experimental results show that the proposed hybrid power conditioning architecture generates up to 5% more energy for a temperature difference between the two modules of only 10°C.     

Energy Storage Systems for Automotive Applications

The fuel efficiency and performance of novel vehicles with electric propulsion capability are largely limited by the performance of the energy storage system (ESS). This paper reviews state-of-the-art ESSs in automotive applications. Battery technology options are considered in detail, with emphasis on methods of battery monitoring, managing, protecting, and balancing. Furthermore, other ESS candidates such as ultracapacitors, flywheels and fuel cells are also discussed. Finally, hybrid power sources are considered as a method of combining two or more energy storage devices to create a superior power source.     

Enhanced power factor of poly (3,4-ethyldioxythiophene):poly (styrene sulfonate) (PEDOT:PSS)/RTCVD graphene hybrid films

The thermoelectric generator has been an attractive alternative power source to operate a wireless sensor node. Usually, inorganic compounds are most often used in thermoelectric devices, and hence, are extensively studied due to their superior thermoelectric performance. We have investigated a novel interfacial technique to fabricate a hybrid film of highly conductive PEDOT:PSS (poly 3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) and graphene. Organic materials PEDOT doped with PSS exhibits outstanding electrical properties due to its high conductivity, low bandgap, and energy migration. Furthermore, we utilized graphene fabricated by rapid thermal chemical vapor deposition (RTCVD) as a thermoelectric material. Our results show that the interfacial technique between substrate and hybrid film could be clearly improved due to the UV plasma treatment. The thermoelectric hybrid film of PEDOT:PSS and RTCVD graphene (P/RTG) exhibited an enhanced power factor of 56.28 μW m⁻¹ K⁻² with a Seebeck coefficient of 54.0 μV K⁻¹.     

直驱型风力发电系统概述

直接驱动型风力发电系统由于其更高的机械效率与可靠性,目前得到了越来越多的关注,发展非常快,市场份额不断增长。本文以直驱型风电系统为对象,对直驱风力发电机、变流器以及国内外的直驱风电产品现状进行了概要总结。直驱风力发电机结合全功率变流器具有非常好的应用前景,在性能、可靠性与低电压穿越能力等方面具有一定的优势。