A photovoltaic voltage regulation impact investigation technique.I. Model development

With changing weather patterns or clouds moving over a given utility service area, the power generated by any photovoltaic (PV) power systems in that service area will vary tremendously. Depending on the percentage penetration of these PV systems on a distribution feeder, these variations in the PV systems' performance may cause undesirable voltage fluctuations along the feeder and also may impact the operation of the voltage regulating equipment on the distribution feeder. A computer program was developed to allow the utility engineer to determine the impact of the fluctuating PV generation due to moving cloud patterns. This impact is determined on the distribution system level by monitoring the feeder voltage profile and the operation of any voltage regulating devices. The model is rigorous and includes modeling capabilities beyond those of previous investigations     

Probabilistic production costing for photovoltaics-utility systemswith battery storage

This paper describes a methodology for calculating the production costing of an integrated photovoltaic-utility power system with battery storage. The methodology uses-long term historical data on solar radiation to calculate the probability density function (PDF) of the photovoltaic (PV) power generation. Once the PDF is calculated, PV can be treated as a multi-state unit in a utility system as conventional production costing techniques are applied. The proposed method is simple and easy to implement and numerical examples demonstrate its potential application in a utility system     

北京市太阳能资源与分布式光伏发电项目的时空耦合适宜度研究

分布式光伏发电项目有助于实现"能源-经济-环境"的协调可持续发展.针对区域太阳能资源与分布式光伏发电项目的时空耦合关系开展了研究,以北京地区为研究对象,提出运用多种空间分析方法,从空间地理的新视角探索太阳能资源与分布式光伏发电项目之间的关系,针对区域太阳能资源与分布式光伏发电项目开发区域的时空耦合适宜度进行了科学评估....     

A study of dispersed photovoltaic generation on the PSO system

Results of a study on dispersed photovoltaic (PV) generation on the Public Service Company of Oklahoma (PSO) system with simulated dispersed PV generation are presented. It is found that, with high penetrations of PV, as insolation changes, significant variations in power flows occur on transmission and subtransmission lines that may require changes in system protection and voltage control practices     

跟踪式光伏发电系统研究

根据某地实测的太阳辐射数据,仿真比较了配备有单轴跟踪和双轴跟踪等4种跟踪控制的光伏发电系统与固定式光伏发电系统的太阳辐射利用率。并在此基础上对4种跟踪系统的跟踪角控制规律及跟踪控制方式进行了详细的分析,得出倾纬度角单轴跟踪系统控制规律最为简单,算法实施更为实用的结论。同时,也在理论上证明了采用步进式控制方式的跟踪系统能够在保持较高太阳辐射利用率情况下简化控制系统设计,有利于工程设计及应用。     

Limits on cloud-induced fluctuation in photovoltaic generation

The cost and the effect on utility reliability of rapidly changing PV (photovoltaic) generation on a partly-cloudy day were investigated. When cloud shadows move across a PV array, the array's power output is reduced. It resumes full production when the shadow moves away. The utility must follow these changes with other types of generation. Under certain cloud conditions, these changes can be large and fast. A methodology is presented to assess the cost of such fluctuations in PV generation and their effect on a utility's ability to serve its load. A case study of one large utility in Kansas is performed using this technique     

Enhancement of grid-connected photovoltaic system using ANFIS-GA under different circumstances

In recent years, many different techniques are applied in order to draw maximum power from photovoltaic (PV) modules for changing solar irradiance and temperature conditions. Generally, the output power generation of the PV system depends on the intermittent solar insolation, cell temperature, efficiency of the PV panel and its output voltage level. Consequently, it is essential to track the generated power of the PV system and utilize the collected solar energy optimally. The aim of this paper is to simulate and control a grid-connected PV source by using an adaptive neuro-fuzzy inference system (ANFIS) and genetic algorithm (GA) controller. The data are optimized by GA and then, these optimum values are used in network training. The simulation results indicate that the ANFIS-GA controller can meet the need of load easily with less fluctuation around the maximum power point (MPP) and can increase the convergence speed to achieve the MPP rather than the conventional method. Moreover, to control both line voltage and current, a grid side P/Q controller has been applied. A dynamic modeling, control and simulation study of the PV system is performed with the Matlab/Simulink program.     

双面组件光伏电站最优容配比的研究

通过对采用双面光伏组件的光伏电站(以下简称"双面组件光伏电站")系统效率损失进行分析,发现在光伏组件-逆变器容配比(下文简称"容配比")变化的情况下,逆变器过载损失对此类光伏电站发电量的影响最大.提出了双面组件光伏电站容配比的优化方法,并以太阳能资源Ⅰ、Ⅱ、Ⅲ类地区的典型城市为例,进行了不同容配比和背景反射率下双面组件...     

Long-term field test of solar PV power generation using one-axis 3-position sun tracker

The 1 axis-3 position (1A-3P) sun tracking PV was built and tested to measure the daily and long-term power generation of the solar PV system. A comparative test using a fixed PV and a 1A-3P tracking PV was carried out with two identical stand-alone solar-powered LED lighting systems. The field test in the particular days shows that the 1A-3P tracking PV can generate 35.8% more electricity than the fixed PV in a partly-cloudy weather with daily-total solar irradiation H_T = 11.7 MJ/m² day, or 35.6% in clear weather with H_T = 18.5 MJ/m² day. This indicates that the present 1A-3P tracking PV can perform very close to a dual-axis continuous tracking PV (Kacira et al., 2004). The long-term outdoor test results have shown that the increase of daily power generation of 1A-3P tracking PV increases with increasing daily-total solar irradiation. The increase of monthly-total power generation for 1A-3P sun tracking PV is between 18.5-28.0%. The total power generation increase in the test period from March 1, 2010 to March 31, 2011, is 23.6% in Taipei (an area of low solar energy resource). The long-term performance of the present 1X-3P tracking PV is shown very close to the 1-axis continuous tracking PV in Taiwan (Chang, 2009). If the 1A-3P tracking PV is used in the area of high solar energy resource with yearly-average H_T > 17 MJ/m² day, the increase of total long-term power generation with respect to fixed PV will be higher than 37.5%. This is very close to that of dual-axis continuous tracking PV.The 1A-3P tracker can be easily mounted on the wall of a building. The cost of the whole tracker is about the same as the regular mounting cost of a conventional rooftop PV system. This means that there is no extra cost for 1A-3P PV mounted on buildings. The 1A-3P PV is quite suitable for building-integrated applications.     

A novel real-time simulation technique of photovoltaic generation systems using RTDS

For the performance test of photovoltaic (PV) generation systems, actual system apparatuses: a solar panel, converter system, and load facilities should be installed. It is also hardly possible to compare a maximum power point tracking (MPPT) control scheme with others under the same weather and load conditions in an actual PV generation system. One of the possible alternatives is to realize a transient simulation scheme for PV generation systems under real weather conditions of insolation and surface temperature of solar cell. The authors propose a novel real-time simulation method for PV generation systems under real weather conditions using a real-time digital simulator (RTDS). V--I curves of a real PV panel are tested using electric load device, and a hypothetical network of the tested PV panel is created on the RTDS by arranging electrical components from the customized component model libraries. The real weather conditions, insolation, and temperature of the PV panel, are interfaced through the analog input ports of the RTDS for real-time simulation. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation technique, and also show that cost-effective verification of availability and stability of PV generation systems is possible using the built-in simulator.     

Economic feasibility of large-scale hydro-solar hybrid power including long distance transmission

Solar PV is expected to become the most cost-competitive renewable energy owing to the rapidly decreasing cost of the system. On the other hand, hydropower is a high-quality and reliable regulating power source that can be bundled with solar PV to improve the economic feasibility of long-distance transmitted power. In this paper, a quantification model is established taking into account the regulating capacity of the reservoir, the characteristics of solar generation, and cost of hydro and solar PV with long-distance transmission based on the installed capacity ratio of hydro-solar hybrid power. Results indicate that for hydropower stations with high regulating capacity and generation factor of approximately 0.5, a hydro-solar installed capacity ratio of 1:1 will yield overall optimal economic performance, whereas for hydropower stations with daily regulating capacity reservoir and capacity factor of approximately 0.65, the optimal hydro-solar installed capacity ratio is approximately 1:0.3. In addition, the accuracy of the approach used in this study is verified through operation simulation of a hydro-solar hybrid system including ultra high-voltage direct current (UHVDC) transmission using two case studies in Africa.     

Feasibility of solar technology (photovoltaic) adoption: A case study on Tennessee's poultry industry

The advantages and limitations of solar photovoltaic (PV) systems for energy generation are reviewed under various physical efficiency limits and financial assistance programs. Recent increases in utility and fuel costs in poultry production as well as public awareness of and demand for green power or renewable energy sources have given renewed interest in alternative energy sources. This study seeks to investigate the impact of alternative energy programs, grants and other incentives on the feasibility of solar PV systems in several solar regions within Tennessee's poultry industry. Preliminary results show that incentives exceeding current levels before adoption of solar PV systems would be financially beneficial.     

Analysis of grid connected solar PV system in the southeastern part of Bangladesh

Bangladesh is a potential site of implementing renewable energy system to reduce the severe power crisis throughout the year. According to this, Chittagong is the southeastern part of Bangladesh is also a potential site for implementing renewable energy system such as grid-connected photovoltaic (PV) system. Financial viability and green-house gas emission reduction of solar PV as an electricity generation source are assessed for 500 kW grid connected solar PV system at University of Chittagong, Chittagong. Homer simulation software and monthly average solar radiation data from NASA is used for this task. In the proposed system monthly electricity generation varies between 82.65 MW h and 60.3 MW h throughout the year with a mean value of 68.25 MW h depending on the monthly highest and lowest solar radiation data. It is found that per unit electricity production cost is US$ 0.20 based on project lifetime 25 years. The IRR, equity payback and benefit-cost ratio shows favorable condition for development of the proposed solar PV system in this site. A minimum 664 tones of green-house gas emissions can be reduced annually utilizing the proposed system.     

Economic analysis of solar energy development in North Africa

The economic analysis of solar energy development is the basis of promoting the solar energy planning in north Africa and realizing the clean energy power transmission among continents. In this paper, the cost development trend of photovoltaic(PV) power and concentrating solar power(CSP) generation is analyzed, and the levelized cost of energy (LCOE) of solar power generation is forecasted. Then, taking the development of Tunisian solar energy as an example in the context of transcontinental transmission, PV power with energy storage and PV-CSP power generation are given as two kinds of development plan respectively. The installed capacity configurations of the two schemes are given with production simulation method, and comprehensive LCOE are calculated. The studies show that based on the LCOE forecast value, the LCOE of PV-CSP combined power generation will decrease when the annual utilization hours of transmission channel is increased. It can be chosen as one of important mode of the North Africa solar energy development.     

Technical and economical system comparison of photovoltaic and concentrating solar thermal power systems depending on annual global irradiation

Concentrating solar thermal power and photovoltaics are two major technologies for converting sunlight to electricity. Variations of the annual solar irradiation depending on the site influence their annual efficiency, specific output and electricity generation cost. Detailed technical and economical analyses performed with computer simulations point out differences of solar thermal parabolic trough power plants, non-tracked and two-axis-tracked PV systems. Therefore, 61 sites in Europe and North Africa covering a global annual irradiation range from 923 to 2438 kW h/m² a have been examined. Simulation results are usable irradiation by the systems, specific annual system output and levelled electricity cost. Cost assumptions are made for today's cost and expected cost in 10 years considering different progress ratios. This will lead to a cost reduction by 50% for PV systems and by 40% for solar thermal power plants. The simulation results show where are optimal regions for installing solar thermal trough and tracked PV systems in comparison to non-tracked PV. For low irradiation values the annual output of solar thermal systems is much lower than of PV systems. On the other hand, for high irradiations solar thermal systems provide the best-cost solution even when considering higher cost reduction factors for PV in the next decade. Electricity generation cost much below 10 Eurocents per kW h for solar thermal systems and about 12 Eurocents/kW h for PV can be expected in 10 years in North Africa.     

串并联太阳能电池弧形光伏组件的发电性能研究

将弧形光伏组件安装在建筑和汽车上获取电能,已受到人们越来越多的关注。为获得更高的输出功率,有必要研究由互连太阳能电池组成的、电流不匹配的弧形光伏组件的特性。研究重点关注由串并联太阳能电池组成的弧形光伏组件的发电性能,设计了不同曲率的非平面微型光伏模块,并通过测量获取光伏模块的参数。与平面光伏模块相比,弧形光伏模块的发电量较小。此外,利用二极管模型分析了光伏模块的特性,说明并联比串联功率高的原因。最后研究了实际应用中太阳能电池的互连问题。结果表明,在理想模型下并联能获取更多电能,但大尺寸的光伏模块会产生更大电流,可能会在实际运行中产生额外损耗。因此,在实际应用中设计弧形光伏组件时也应考虑太阳能电池的互连。     

Evaluating the limits of solar photovoltaics (PV) in traditional electric power systems

In this work, we examine some of the limits to large-scale deployment of solar photovoltaics (PV) in traditional electric power systems. Specifically, we evaluate the ability of PV to provide a large fraction (up to 50%) of a utility system's energy by comparing hourly output of a simulated large PV system to the amount of electricity actually usable. The simulations use hourly recorded solar insolation and load data for Texas in the year 2000 and consider the constraints of traditional electricity generation plants to reduce output and accommodate intermittent PV generation. We find that under high penetration levels and existing grid-operation procedures and rules, the system will have excess PV generation during certain periods of the year. Several metrics are developed to examine this excess PV generation and resulting costs as a function of PV penetration at different levels of system flexibility. The limited flexibility of base load generators produces increasingly large amounts of unusable PV generation when PV provides perhaps 10–20% of a system's energy. Measures to increase PV penetration beyond this range will be discussed and quantified in a follow-up analysis.     

Study on islanding of dispersed photovoltaic power systems connected to a utility power grid

Photovoltaic (PV) systems and other dispersed power systems need to be connected to a utility power grid for the systems to work effectively as energy sources. Protection against islanding is one of the most important techniques to develop for the dispersed power systems supplying surplus power back to the utility power grid. It is considered that active methods where the outputs of the power systems are actively perturbed are necessary to detect islanding. Various active methods have been developed. It has been shown that these methods work when a single power system is connected to one power distribution line. However, most of these methods have a limit in detecting islanding when multiple power systems are connected to one distribution line. In this paper, we compare the detection characteristics of typical active methods, frequency shift methods, a pulse perturbation method and a method using a correlation technique by simulation analysis for the case of multiple PV power systems. The study shows that the method using the correlation technique is the most promising when multiple power systems are operated on one distribution line.     

我国光伏产业发展对策探讨

光伏发电是解决能源供应短缺和环境污染问题的有效途径,在国内政策以及外部有利市场环境的推动下,我国太阳能光伏产业发展迅速,在光伏制造业等领域已走在世界前列。2010年,国内光伏电池产量已达9GW,连续4年居世界首位;多晶硅产量已达4.5×104t。但我国光伏发电市场发展规模仍然较小,影响了光伏产业的总体可持续发展。2010年国内新增光伏发电装机容量500MW,仅占全球光伏新增装机容量的3%,国内光伏电池生产的销售市场对外依存度高达95%,产业发展具有极大的危险性。其主要原因是产业规划保守,发展目标低定;发电成本较高,民众承受能力有限;光伏电力的"间歇性"特征以及电网企业的国有垄断地位使得"入网难"问题仍未解决;投资回收期长,资本盈利率不高;地方政府追求短期经济效益,抓快放慢。德国在这方面的发展经验值得借鉴。当前,应在提高光伏发电占新能源产业发展规划比重、降低光伏产业对外依存度的同时,努力降低发电成本,同时大力发展规模储能和智能电网技术,并构建有力的政策支持环境,从根本上提升业界信心,实现我国光伏发电产业的大发展。     

Estimation of the PV potential in ASEAN with a high spatial and temporal resolution

Further exploitation of renewable energy sources for power generation could mitigate the current rapid increase of greenhouse gas emissions in South East Asia. In this context, solar PV is a promising option as PV system costs have been declining continuously over the past. In order to define strategies towards a low-carbon future power supply, detailed information on the potential power output of solar PV is essential.Therefore, this paper analyses the resource and technical potential of solar PV in South East Asia in high temporal and spatial resolution. An empirical, climate-based Ångström-Prescott model is proposed in order to adjust MERRA solar radiation data. The possible power output of PV is derived considering topographic and land-use constraints as well as technological characteristics of typical PV systems.Java, central Myanmar and eastern Thailand were identified to be the best locations for PV use, with capacity factors exceeding 15%. Due to the large land area which is suitable for PV installations, South East Asia offers an abundant theoretical potential of solar PV, amounting to 430 TW h with conservative assumptions.