基于NSGA-Ⅱ的风光互补独立供电系统多目标优化

在风光互补独立供电系统的设计中,系统的优化配置是一个重要步骤。风光资源、发电、储能和负载之间有复杂的匹配关系。风光互补独立供电系统的优化配置可看作一个多目标优化问题,两个相互冲突的目标是极大化供电可靠性和极小化成本,供电可靠性指标负载缺电率LPSP需经仿真运行得到。优化算法采用精英非支配解排序遗传算法(NSGA-Ⅱ),决策变量不仅有传统算法中的光伏电池和蓄电池的容量,还增加了风力发电机的类型和容量以及光伏电池的倾角。经传统算法及ε-约束法验证表明,NSGA-Ⅱ得出的非支配解前沿面就是Pareto前沿面。     

离网型风光互补系统控制策略探讨

分析了太阳能电池和风力发电机的工作原理和工作特性,建立了太阳能光伏电池和风力发电机的仿真模型,采用扰动观察法,分别对其进行最大功率跟踪控制。针对扰动观察法步长难以选择的问题,分别对太阳能光伏发电系统和风力发电系统设计了相应的模糊控制器。仿真结果表明:所采用的控制策略可以随着条件的变化进行实时地跟踪控制。最后,分析了蓄电池的工作原理及工作特性,探讨采用蓄电池(激活充电、主充电、均充电及浮充电)4阶段充电管理的方法,模拟结果显示了方法的可行性。     

光储微网的储能优化配置与技术经济分析

在储能系统和光伏发电相结合的统筹规划中,电池储能投资成本、光伏装机容量、光伏并网价格以及热电联产(CHP)的采用对电池储能的容量配置和电池充放电策略具有显著影响。基于分时电价下的光伏储能系统,将电池储能的容量和功率的配置转化为根据电价时段划分的约束优化问题。以某工业园区为研究对象,建立光伏-储能系统功率流模型,优化计算得到经济效益最优化的电池容量和功率配置结果及电池充放电策略。基于内部收益率、光伏自我消纳率等指标,根据光伏上网价格和电网谷段电价的关系划分场景,通过光伏发电容量和电池价格的变化探究光伏-储能系统中电池储能的容量配置、经济效益的变化规律和热电联产对系统的影响。     

风光互补电动汽车储能电站系统优化设计

通过对唐山市区太阳能和风能资源状况调查分析,对全年不同方位角和倾角上的太阳能辐射量进行模拟计算,得出南偏东9.8°方向、倾角为39.7°的倾斜面上接收的太阳能辐射量最大,其值为1.62×106Wh/m2。研究中对3kW风力发电机和1kW光伏发电系统的发电量进行了计算,并以1辆纯电动轿车为负载进行了容量配比优化,设计了风力发电系统、风光互补系统及光伏系统三种不同的方案,经过对各方案的经济性、可靠性及稳定性分析,得出最佳的设计方案为风光互补发电系统,该系统风力发电装机容量为3kW,光伏发电装机容量为8.96kW。     

微风机储能蓄电池容量的合理匹配

储能蓄电池容量匹配合理与否,直接关系微型风力发电机整机使用效果。本文在微型风力发电机实际应用经验的基础上,将理论计算与实用分析相结合,合理地确定微型风力电机储能蓄电池容量的匹配。     

风光互补发电技术在路灯照明中的应用

风光互补发电系统是由风力发电机、光伏组件、控制器、蓄电池、负载等组成的微型发电系统。系统以控制器为核心,由风力发电机、光伏组件把风能和光能转变为电能并储存于蓄电池中供负载使用。风光互补发电技术在路灯供电方面的应用,能充分利用绿色环保的可再生能源,具有深远的社会效益和长远的经济效益。     

不停电独立光伏系统的优化设计

为零缺电率负载供电的独立光伏系统是对设计要求最高的光伏系统,必须慎重地进行优化设计。研究表明,如果采用一般的独立光伏系统优化设计程序来进行设计,只要用蓄电池维持天数等于零代入,即可确定太阳电池方阵的容量,同时可以用当地辐照量最低的月份得到最大辐照量所对应的倾角作为方阵的最佳倾角。确定蓄电池容量时应以当地最长连阴雨天数作为蓄电池维持天数的依据。通过实例分析,取得了良好的效果。     

风光互补发电系统的优化设计(I) CAD设计方法

给出了一整套利用CAD进行风光互补发电系统优化设计的方法。为了精确确定系统每小时的运行状态,采用了更精确地表征组件特性及评估实际获得的风光资源的数学模型。为了寻找出以最小设备投资成本满足用户用电要求的系统配置,首先在风力发电机容量固定不变的前提下,计算了与该容量风力发电机匹配的不同容量的PV方阵和蓄电池所组成的风/光/蓄组合的全年功率供给亏欠率LPSP,根据总的设备投资成本最小化的原则筛选出一组与该容量风力发电机对应的满足用户给定系统供电可靠性即LPSP值的风/光/蓄组合;然后通过改变风力发电机的容量,优选出多个与不同容量风力发电机对应的既能满足用户用电要求同时总的设备购置成本又是最低的风/光/蓄组合,比较它们的成本最终唯一确定出以最小投资成本满足用户用电要求的优化的系统配置。     

KF—100型风力发电机充放电控制器

FK—100型风力发电机充放电控制器,是使用100瓦风力发电机及蓄电池供电时所必备的配套产品,风力发电机为间歇工作的电源。连续供电,需备有蓄电池,而蓄电池无此控制器,则极易因电池过充过放电缩短使用寿命。本控制器能自动控制充电放电,以保护电池,     

风光互补发电系统的优化设计（I）CAD设计方法

给出了一整套利用CAD进行风光互补发电系统优化设计的方法。为了精确确定系统每小时的运行状态,采用了更精确地表征组件特性及评估实际获得的风光资源的数学模型。为了寻找出以最小设备投资成本满足用户用电要求的系统配置,首先在风力发电机容量固定不变的前提下,计算了与该容量风力发电机匹配的不同容量的PV方阵和蓄电池所组成的风／光／蓄组合的全年功率供给亏欠率LPSP,根据总的设备投资成本最小化的原则筛选出一组与该容量风力发电机对应的满足用户给定系统供电可靠性即LPSP值的风／光／蓄组合;然后通过改变风力发电机的容量,优选出多个与不同容量风力发电机对应的既能满足用户用电要求同时总的设备购置成本又是最低的风／光／蓄组合,比较它们的成本最终唯一确定出以最小投资成本满足用户用电要求的优化的系统配置。     

Methodology for optimally sizing the combination of a battery bankand PV array in a wind/PV hybrid system

In this paper, a methodology for calculation of the optimum size of a battery bank and the PV array for a standalone hybrid wind/PV power system is developed. Long term data of wind speed and irradiance recorded for every hour of the day for 30 years were used. These data were used to calculate the average power generated by a wind turbine and a PV module for every hour of a typical day in a month. A load of a typical house in Massachusetts, USA, was used as a load demand of the hybrid system. For a given load and a desired loss of power supply probability, an optimum number of batteries and PV modules was calculated based on the minimum cost of the power system     

A comprehensive method for optimal power management and design of hybrid RES-based autonomous energy systems

The power management strategy (PMS) plays an important role in the optimum design and efficient utilization of hybrid energy systems. The power available from hybrid systems and the overall lifetime of system components are highly affected by PMS. This paper presents a novel method for the determination of the optimum PMS of hybrid energy systems including various generators and storage units. The PMS optimization is integrated with the sizing procedure of the hybrid system. The method is tested on a system with several widely used generators in off-grid systems, including wind turbines, PV panels, fuel cells, electrolyzers, hydrogen tanks, batteries, and diesel generators. The aim of the optimization problem is to simultaneously minimize the overall cost of the system, unmet load, and fuel emission considering the uncertainties associated with renewable energy sources (RES). These uncertainties are modeled by using various possible scenarios for wind speed and solar irradiation based on Weibull and Beta probability distribution functions (PDF), respectively. The differential evolution algorithm (DEA) accompanied with fuzzy technique is used to handle the mixed-integer nonlinear multi-objective optimization problem. The optimum solution, including design parameters of system components and the monthly PMS parameters adapting climatic changes during a year, are obtained. Considering operating limitations of system devices, the parameters characterize the priority and share of each storage component for serving the deficit energy or storing surplus energy both resulted from the mismatch of power between load and generation. In order to have efficient power exploitation from RES, the optimum monthly tilt angles of PV panels and the optimum tower height for wind turbines are calculated. Numerical results are compared with the results of optimal sizing assuming pre-defined PMS without using the proposed power management optimization method. The comparative results present the efficacy and capability of the proposed method for hybrid energy systems.     

An integrated control method for a wind farm to reduce frequency deviations in a small power system

Output power of wind turbine generator (WTG) is not constant and fluctuates due to wind speed changes. To reduce the adverse effects of the power system introducing WTGs, there are several published reports on output power control of WTGs detailing various researches based on pitch angle control, variable speed wind turbines, energy storage systems, and so on. In this context, this paper presents an integrated control method for a WF to reduce frequency deviations in a small power system. In this study, the WF achieves the frequency control with two control schemes: load estimation and short-term ahead wind speed prediction. For load estimation in the small power system, a minimal-order observer is used as disturbance observer. The estimated load is utilized to determine the output power command of the WF. To regulate the output power command of the WF according to wind speed changing, short-term ahead wind speed is predicted by using least-squares method. The predicted wind speed adjusts the output power command of the WF as a multiplying factor with fuzzy reasoning. By means of the proposed method, the WF can operate according to the wind and load conditions. In the WF system, each output power of the WTGs is controlled by regulating each pitch angle. For increasing acquisition power of the WF, a dispatch control method also is proposed. In the pitch angle control system of each WTG, generalized predictive control (GPC) is applied to enhance the control performance. Effectiveness of the proposed method is verified by the numerical simulations.     

Concentrating solar module with horizontal reflectors

A non-sun-tracking concentrating solar module is described that is designed to achieve photovoltaic (PV) systems with higher generation power density. The proposed concentrating module consists of a solar panel having a higher tilt angle than that of a conventional one and with a solar reflector placed in front of the solar panel on a downward inclination angle towards the panel. As a result of this configuration, the solar panel receives reflected as well as direct sunlight so that maximum irradiance and short-circuit current were increased. This configuration is expected to reduce the area required for solar panels, resulting in lower cost PV system.     

Cost analysis of off-grid renewable hybrid power generation system on Ui Island,South Korea

Diesel engine power plants are still widely used on many remote islands in South Korea, despite their disadvantages. Aiming to solve economic and environmental pollution problems, a remote island case study was conducted on Ui Island, aiming to offer a zero-emissions solution by using renewable energy sources in an off-grid application. Power was generated from solar, wind, and hydrogen sources. Li-ion batteries and hydrogen were used as energy storage systems. In addition, PV/battery, wind/battery, PV/wind/battery, PV/battery/PEMFC, wind/battery/PEMFC, and PV/wind/battery/PEMFC systems were simulated using the HOMER software to determine the optimal sizes and techno-economic feasibility. The results show that the PV/wind/battery/PEMFC system is the best system. The configuration of the system consists of 990-kW PV panels, 700-kW wind turbines, a 1088-kWh Li-ion battery bank, 534-kW converter, 300-kW PEMWE system, 300-kg hydrogen tank, and 100-kW PEMFC system. The total NPC of the system is $5,276,069, and the LCOE is 0.366 $/kWh.     

Output power dispatch control for a wind farm in a small power system

Nowadays, a wind turbine generator (WTG) is required to provide control capabilities as the output power of WTG fluctuates. Under this scenario, this paper proposes an output power control method of a wind farm (WF) connected to a small power system using pitch angle control. In this control approach, the WF output power control is achieved by two control levels: central and local. In the central control, the WF output power command is determined by considering the frequency deviations and wind speeds using a fuzzy function. Then, the local output power commands for each of the WTGs are based on the proposed dispatch control. In the proposed dispatch control, the output commands of each WTG are determined by considering wind conditions for each of the WTGs. The simulation results by using an actual detailed model for the wind power system show the effectiveness of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd.     

A mobile off-grid platform powered with photovoltaic/wind/battery/fuel cell hybrid power systems

Cross utilization of photovoltaic/wind/battery/fuel cell hybrid-power-system has been demonstrated to power an off-grid mobile living space. This concept shows that different renewable energy sources can be used simultaneously to power off-grid applications together with battery and hydrogen energy storage options. Photovoltaic (PV) and wind energy are used as primary sources and a fuel cell is used as backup power. A total of 2.7 kW energy production (wind and PV panels) along with 1.2 kW fuel cell power is supported with 17.2 kWh battery and 15 kWh hydrogen storage capacities. Supply/demand scenarios are prepared based on wind and solar data for Istanbul. Primary energy sources supply load and charge batteries. When there is energy excess, it is used to electrolyse water for hydrogen production, which in turn can either be used to power fuel cells or burnt as fuel by the hydrogen cooker. Power-to-gas and gas-to-power schemes are effectively utilized and shown in this study. Power demand by the installed equipment is supplied by batteries if no renewable energy is available. If there is high demand beyond battery capacity, fuel cell supplies energy in parallel. Automatic and manual controllable hydraulic systems are designed and installed to increase the photovoltaic efficiency by vertical axis control, to lift up & down wind turbine and to prevent vibrations on vehicle. Automatic control, data acquisition, monitoring, telemetry hardware and software are established. In order to increase public awareness of renewable energy sources and its applications, system has been demonstrated in various exhibitions, conferences, energy forums, universities, governmental and nongovernmental organizations in Turkey, Austria, United Arab Emirates and Romania.     

Modeling,design, and optimization of a cost‐effective and reliable hybrid renewable energy system integrated with desalination using the division algorithm

People in the Middle East are facing the problem of freshwater shortages. This problem is more intense for a remote region, which has no access to the power grid. The use of seawater desalination technology integrated with the generated energy unit by renewable energy sources could help overcome this problem. In this study, we refer a seawater reverse osmosis desalination (SWROD) plant with a capacity of 1.5 m³/h used on Larak Island, Iran. Moreover, for producing fresh water and meet the load demand of the SWROD plant, three different stand‐alone hybrid renewable energy systems (SAHRES), namely wind turbine (WT)/photovoltaic (PV)/battery bank storage (BBS), PV/BBS, and WT/BBS are modeled and investigated. The optimization problem was coded in MATLAB software. Furthermore, the optimized results were obtained by the division algorithm (DA). The DA has been developed to solve the sizing problem of three SAHRES configurations by considering the object function's constraints. These results show that this improved algorithm has been simpler, more precise, faster, and more flexible than a genetic algorithm (GA) in solving problems. Moreover, the minimum total life cycle cost (TLCC = 243 763$), with minimum loss of power supply probability (LPSP = 0%) and maximum reliability, was related to the WT/PV/BBS configuration. WT/PV/BBS is also the best configuration to use less battery as a backup unit (69 units). The batteries in this configuration have a longer life cycle (maximum average of annual battery charge level) than two other configurations (93.86%). Moreover, the optimized results have shown that utilizing the configuration of WT/PV/BBS could lead to attaining a cost‐effective and green (without environmental pollution) SAHRES, with high reliability for remote areas, with appropriate potential of wind and solar irradiance.     

A review on scale and siting of wind farms in China

Using a wind power information system, which is based on the geographic information system (GIS), this paper presents a statistical analysis of built and approved wind farms to the end of 2008. The average capacity of wind turbine generators (WTGs) and the scale of wind farms are investigated. The geographical distribution of wind farms and the main factors affecting wind farm siting are analysed. The results show: (i) The average capacity of WTGs is increasing; MW scale WTGs have become the mainstream product in the China market. (ii) Because of the national wind project approval policy, most of the wind farms have installed capacities of just under 50 MW. (iii) When siting a wind farm, wind resource is still the predominant factor being considered, while grid connection is still the main constraint in this stage. (iv) Concerning land use, among the wind farms built by 2008, 40% use grasslands, 31% use agricultural land, 17% use desert or bare lands, while 12% use farmlands. (v) Statistics show 88.6% of the built wind farms have elevation change of less than 300 m, and 90% of the built wind farms have GIS slopes of less than 10°. (vi) The geographical distribution of wind farms reveals a highly concentrated deployment tendency, 58.7% of all the newly built wind farms in 2008 are within 10 km of existing wind farms. Copyright © 2010 John Wiley & Sons, Ltd.