Numerical analysis for a proposed hybrid system with single HAWT,double HATCT and vertical oscillating wave energy converters on a single tower

South Korea has huge renewable energy potential that has been to some extent and can be further extracted to reduce its heavy reliance on fossil fuels. This project focuses on ocean and coastal wind resources available in the south-western regions of Korea that are currently being monitored and found to have huge potential. The project will propose a new concept of wind, tidal current and wave energy converting systems combined together that can boost output power capacity at a single location also making it easier for grid connection. Wind turbines nowadays have been quite efficiently developed and implemented throughout the world both onshore and offshore. However, tidal current and wave energy have yet more room for improvement. The current study will combine the offshore wind turbine (HAWT) system with two tidal current turbines (HATCT) both in horizontal axis classification on a single tower. It will further discuss on adding a wave energy converter in between the wind and tidal current turbines. Optimization of the tower is also a minor part of this study. The structural analysis of the main tower, which is the main focus of the study, is investigated by dynamic response analysis to check its feasibility for combining the three types of renewable energy converters on one support. Actual extreme conditions of the wind, ocean currents and waves are simulated using ANSYS CFX fluid flow analysis. The results are used for conducting a one way FSI analysis assuming a rigid structure to verify the safety of the system.

     

Comparison of different power generators in PV-battery-power generator hybrid system

Nowadays, the use of solar panels for generating electricity is common. Given the discontinuous nature of solar energy, the use of batteries to store energy in the day and supply it at night is essential. However, using one auxiliary power system (APS) can reduce the number of solar panels needed, reduce the cost, and increase reliability. In this study, the combination of different auxiliary systems with solar panels and batteries is compared in terms of economical efficiency, ecological compatibility, and reliability. Auxiliary systems include diesel generator, gas generator, solid oxide fuel cell (SOFC), and micro gas turbine. Of course, in this study, the effect of fuel price, technology development in SOFC cost, change in the power of auxiliary power system and also change in the maximum number of panels have been considered. A multi-objective evolutionary algorithm was used to obtain the best solutions of every configuration. The evolutionary algorithm is Pareto envelope-based selection algorithm (PESA). According to the results and necessity of using a backup power generator, the most ecological and economical recommended hybrid system is the hybrid system with target SOFC. Therefore, if SOFC technology develops rapidly, using SOFCs as the auxiliary system will be cheaper than others and ecologically the most compatible. Also from ecological point of view, the use of systems such as gas generators or diesel generators is not justified.     

一种实用型风力发电装置的设计

风能是一种干净的可再生能源,利用风能进行发电不需要燃料、不会产生辐射或空气污染,具有广阔的发展前景。研究和推广小型风力发电机对于解决边远山区的生产、生活用电,推动生态环境建设等领域的发展将发挥积极作用。但是,目前市场上的小型风力发电机价格一般都较高,因此如何降低成本,研发实用型的小型风力发电机是科技人员急需解决的课题。本文主要针对家庭中的照明和一些小型电器的用电,设计出一种实用型的风力发电装置。     

A study on the design of a new power transmission for wind turbines

The single-rotor wind turbine remains the dominant design for energy production. However, this design requires improvements to overcome some of its limitations. The introduction of the dual rotor system regarded as improvement over the single-rotor system in Korea due to its high efficiency, despite Korea’s low wind quality. Many researchers have attempted to devise different dual rotor machines and assess their power production capabilities under similar wind conditions to those in Korea. Existing power transmissions for dual-rotor wind turbines have issues with the complexity of design, difficulty in manufacturing, high costs and low efficiencies. Therefore, the aim of this study was to design a new power transmission for the dual-rotor wind turbine with an alternative to the bevel-planetary system by using a planetary system. This new method is dependent on the torque ratio and not the gear ratio as in common gear systems. The design and analysis of each part, such as the gears, shafts, bearings and control mechanisms are included in this study. The design is based on the power transmission of a motor vehicle. A prototype of the design is manufactured to verify the proposed method. The experimental results show that the new planetary-type gear box incurs fewer energy losses, has a high efficiency and low manufacturing costs. It is anticipated that the proposed design might be suitable for use with commercial wind turbines.     

Exergy performance analysis of the conceptual district energy network system with heat pump

To increase the efficiency of a district heating system, we propose a district energy network concept which combines several heating resources with additional electric heat pump and thermal energy storage. With help of thermal energy storage, a heat pump can be operated at maximum efficiency at all the time. Electricity generated with less CO₂ emission makes the proposed system much more environmentally friendly. Even though the proposed concept can be applied to any given situation, a specific target area was chosen to show the effectiveness of the newly proposed energy network concept more clearly. Several constraints were applied for the selection process and a simplified model used for quantitative comparison between the existing and the developed concept. Exergy analysis showed the increased performance of proposed energy network system. The result showed that the newly proposed concept generates less CO₂ emission by 46% at maximum compared to the existing system. By using additional renewable energy sources, we can reduce CO₂ emission even further.     

Modeling,control, and simulation of grid connected intelligent hybrid battery/photovoltaic system using new hybrid fuzzy-neural method

Nowadays, photovoltaic (PV) generation is growing increasingly fast as a renewable energy source. Nevertheless, the drawback of the PV system is its dependence on weather conditions. Therefore, battery energy storage (BES) can be considered to assist for a stable and reliable output from PV generation system for loads and improve the dynamic performance of the whole generation system in grid connected mode. In this paper, a novel topology of intelligent hybrid generation systems with PV and BES in a DC-coupled structure is presented. Each photovoltaic cell has a specific point named maximum power point on its operational curve (i.e. current–voltage or power–voltage curve) in which it can generate maximum power. Irradiance and temperature changes affect these operational curves. Therefore, the nonlinear characteristic of maximum power point to environment has caused to development of different maximum power point tracking techniques. In order to capture the maximum power point (MPP), a hybrid fuzzy-neural maximum power point tracking (MPPT) method is applied in the PV system. Obtained results represent the effectiveness and superiority of the proposed method, and the average tracking efficiency of the hybrid fuzzy-neural is incremented by approximately two percentage points in comparison to the conventional methods. It has the advantages of robustness, fast response and good performance. A detailed mathematical model and a control approach of a three-phase grid-connected intelligent hybrid system have been proposed using Matlab/Simulink.     

抽水蓄能电站可逆机组关闭规律研究

评述了目前抽水蓄能可逆机组常用的分段折线关闭规律；针对可逆机组独特的过流特性，设计了具有延时段的三段折线关闭规律，在减少总关闭时间的同时，有效的降低了抽水蓄能可逆机组由于导叶关闭与机组转速上升联合作用引起的水锤压力；介绍了考虑转速信号反馈的可逆机组导叶关机规律；为抽水蓄能可逆机组的事故紧急关机规律的设计提供了一种新思路。     

预开导叶下水泵水轮机S特性及其压力脉动分析

可逆式水泵水轮机兼具了发电以及储能的特点既满足人们环保意识的需求也满足对功率的平衡与控制。但水泵水轮机在S特性区内运行会发生机组并网困难或者甩负荷过程中水压异常上升,使机组振动加剧。为探究预开启导叶的方法对水泵水轮机S特性的改善,对水泵水轮机模型分别在同步导叶和不同预开启导叶条件下进行能量试验及全流道内流场的(Computational fluid dynamics,CFD)数值计算;通过试验数据与计算结果的对比分析预开导叶后水泵水轮机S特性及其压力脉动特征。CFD计算结果及模型试验数据表明,预开导叶的方法能有效解决水泵水轮机S特性问题,但是预开导叶后,飞逸工况下的单位流量变大,造成转轮内的流动轴对称特性较差,导致机组的脉动加大,尾水管压力脉动幅值较大,运行稳定性较差,所以通过预开导叶的方法来改善S特性仍然存在弊端。     

电容器型混合动力货运车的开发

开发了一种采用电容型器的混合动力的中型货运车,该车装备了一新型高蓄能的电容,可以实现更高的效率和更低的废气排放。该种新开发的电容器能够提供比一般的商业用的强电容多一倍的能量。货运车系统包括新电容、电机、传统的柴油发动机和机械式自动变速装置。燃油经济性比传统的柴油机高1.5倍。此外,废气排放也达到了的TLEV标准。     

基于卷扬机储能系统的超级电容充放电试验研究

超级电容器是一种性能优良的新型能源器件,工程应用设计需掌握其容量、工作电压、充电效率、放电效率等指标.设计了卷扬机储能系统,对超级电容放电时重物提升速度及其放电效率,以及重物下放时重力势能回收到超级电容的充电效率进行了试验研究,实现了机械装置与超级电容的混合储能,为超级电容的研究及其在工程机械中的应用提供参考.     

家用太阳能光伏发电系统设计

太阳能是最普遍的自然资源,也是取之不尽的可再生能源.为解决边远的农牧地区、偏僻的山区、孤立的岛屿等地方人们日常生活、生产用电的需要,改善人们的生活水平,进行了家用太阳能光伏发电系统的设计.根据当地的气象、环境状况及具体用电情况,给出了系统的设计方法及施工要求,包括蓄电池容量的计算、控制器的选择、逆变器功率的选择、太阳能...     

油电混合动力挖掘机的关键技术研究

面对全球性的能源危机和环境污染,量大面广的挖掘机亟须在技术上寻求新的解决方案。油电混合动力技术采用发动机和电机复合驱动来改善发动机燃油经济性并可进行能量回收,是公认的节能减排最佳方案之一,已在车辆领域取得了卓有成效的进展。由于挖掘机与车辆在负载工况、能量回收途径、储能装置、操作性及可靠性等方面存在显著差异,须对挖掘机的混合动力技术开展专项研究。概述国内外、特别是浙江大学流体动力与机电系统国家重点实验室在动力复合模式与参数优化、动力系统控制、电动回转及制动能量回收、动臂势能回收及能量回收电机等油电混合动力挖掘机关键技术方面的解决方案及研究成果,并在研制的20 t混合动力挖掘机综合试验样机上得到充分验证。这些研究成果对油电混合动力技术在其他工程机械上的应用推广也具有重要意义。     

基于NSGA-Ⅱ算法的储能式有轨电车复合电源参数优化设计

为研究一类以动力电池和超级电容为复合电源的有轨电车参数匹配问题,提出一种基于多目标优化的复合电源参数设计方法。根据有轨电车的动力性能需求,给出基于等效计算的复合电源参数设计方法。以有轨电车日均运行成本和动力电池的性能衰减率为评价指标,建立多目标优化函数,采用带精英策略的非支配排序的遗传算法（NSGA-Ⅱ）,设计系统仿真模型在环的复合电源参数优化流程。以一次往返行程为运营要求,对比分析两个不同工况的Pareto解集和等效计算配置方案下的有轨电车系统仿真结果。结果表明,相比等效计算的配置方案,优化的配置方案使动力电池性能衰减率降低至少约31.1%;合理的配置方案可有效保证较高的再生制动能量回收率和有轨电车效率;长站间距的工况增加了对复合电源的配置需求。     

浅析柴油发电机的现场维修与远程故障诊断系统

目前,柴油发电机已经广泛应用于我国的诸多工业领域之中。由于损耗小、启动速度快、发电速率高等特点,柴油发电机已经成为了相关领域紧急供电的首要选择。柴油发电机在供电保障系统中的意义重大,因此,相关工作人员要做好对柴油发电机的定期检查和维修。通过现场维修来确保柴油发电机的正常工作,通过远程故障诊断系统来提高自身的工作效率,相信柴油发电机的现场维修与远程故障诊断系统这两项维修措施的正确实施,可以有效保障相关领域、相关部门的应急电源。     

插电式电动汽车入网体系框架研究

为解决未来电动汽车(EVs)普及所带来的能源供应紧缺及其接入对电网的影响等问题,将车辆入网(V2G)技术应用到智能电网中。简要综述了V2G概念及研究现状,探讨了在中国实现EV入网的几种模式,提出了在未来中国智能电网环境下EV通过微网并与大电网进行融合的框架结构,从电网技术操作与电力市场经济两方面,对所有参与EV入网过程与活动的参与者作了描述,最后给出了需要开展研究的技术重点和方向。研究结果表明,该V2G技术及其体系框架可充分利用车载储能系统与电网功率进行双向互动,支持大规模可再生能源利用,提高电力系统效率及稳定性,加快电动汽车普及。     

Feasibility study of a hybrid renewable energy system with geothermal and solar heat sources for residential buildings in South Korea

This study investigates the economic feasibility of a hybrid renewable energy system (HRES) that uses geothermal and solar heat sources for water heating, space heating, and space cooling in a residential building in Korea. A small-scale HRES consists of a geothermal heat pump for heating and cooling, solar collectors for hot water, a gas-fired backup boiler, and incidental facilities. To determine whether the HRES will produce any economic benefits for homeowners, an economic analysis is conducted to compare the HRES with conventional methods of space heating and cooling in Korea. The payback period of a small-scale HRES is predicted as a maximum of 9 yrs by life cycle costing based on a performance index compared with conventional systems. However, the payback period of large-scale HRES above 400 RT is 6 yrs to 7 yrs.     

Realization and Analysis of Good Fuel Economy and Kinetic Performance of a Low-cost Hybrid Electric Vehicle

By using high-power and high-efficiency propulsion systems,current hybrid electric vehicles(HEVs) in market can achieve excellent fuel economy and kinetic performance.However,it is the cost of current HEVs that hinders HEVs coming into widespread use.A novel hybrid electric propulsion system is designed to balance HEV cost and performance for developing markets.A battery/supercapacitor-based hybrid energy storage system(HESS) is used to improve energy conversion efficiency and reduce battery size and cost.An all-in-one-controller(AIOC) which integrates engine electronic control unit(ECU),motor ECU,and HESS management system is developed to save materials and energy,and reduce the influence of distribution parameters on circuit.As for the powertrain configuration,four schemes are presented:belt-driven starter generator(BSG) scheme,four-wheel drive HEV scheme,full HEV scheme,and ranger-extender electric vehicle(EV) scheme.Component selection and parameter matching for the propulsion system are performed,and an energy management strategy is developed based on powertrain configuration and selected components.Forward-facing simulation models are built,comprehending the control strategy based on the optimal engine torque for the low-cost hybrid electric propulsion system.Co-simulation of AVL CRUISE and Matlab/Simulink is presented and the best scheme is selected.The simulation results indicate that,for the best design,fuel consumption in urban driving condition is 4.11 L/(100 km) and 0-50 km/h accelerating time is 10.95 s.The proposed research can realize low-cost concept for HEV while achieving satisfactory fuel economy and kinetic performance,and help to improve commercialization of HEVs.     

A study on the energy efficiency improvement of greenhouses — with a focus on the theoretical and experimental analyses

Most greenhouses in Korea are made according to European weather conditions, which leads to very low solar energy efficiency under the domestic weather conditions. Thus, greenhouses in Korea should be adapted to the regional weather conditions to improve their energy efficiency. This paper investigates the current greenhouses in Korea. It also analyzes the problems arising from the greenhouses and offers alternatives for improving their energy efficiency based on measurements and a theoretical analysis. The elements of greenhouses were also investigated. When using a partially non-transparent insulation with heat storage mass between the indoor and outdoor air, the temperature difference became greater than 20°C during the daytime and greater than 5°C during the night, which will reduce the cost of fossil fuels.     

纯电动汽车复合电源能量管理控制策略研究

蓄电池循环寿命短、充放电效率低等缺陷制约了纯电动汽车储能系统的发展,将蓄电池与超级电容器组合成复合电源系统,并采用合理的能量管理控制策略,充分发挥两类能量源的优势,能有效降低纯电动汽车的能量消耗、提高储能系统的使用寿命。根据复合电源的工作方式设计了模糊逻辑能量管理控制策略,采用遗传算法对模糊控制器隶属度函数参数进行了优化。通过MATLAB与ADVISOR联合仿真,结果表明,经遗传算法优化后的能量管理控制策略能够显著降低系统的总能耗,提高制动能量回收效率,改善蓄电池放电状态,并提高储能系统的使用寿命。     

具有能量获取能力的低功耗ZigBee无线传感器网络节点设计

基于ZigBee技术的无线传感器网络具有巨大的应用前景。由于网络节点能量有限,如何设计低能耗的ZigBee无线传感器网络节点,最大限度地利用自身能量,同时从环境尽可能获取能量,是提高网络节点生命周期的二大关键问题。本文一方面系统分析了ZigBee无线传感器网络节点中各个部分引起的能量消耗,提出从节点硬件结构和网络协议两方面来降低网络系统能耗,延长网络生命周期的策略。另一方面提出从环境中获取能量的ZigBee无线传感器节点设计思想,设计开发了具有能量自获取能力的ZigBee无线传感器网络节点,用太阳能光伏电池和风能发电机作为生能器件,用超级电容器和锂离子电池作为储存器件,并采用低功耗的能量获取管理策略,实现了能量的自动获取与充分利用。