Parametric study of hybrid (wind + solar + diesel) power generating systems

The combined utilization of renewables such as solar and wind energy is becoming increasingly attractive and is being widely used for substitution of oil-produced energy, and eventually to reduce air pollution. In the present investigation, hourly wind-speed and solar radiation measurements made at the solar radiation and meteorological monitoring station, Dhahran (26°32′N, 50°13′E), Saudi Arabia, have been analyzed to study the impact of key parameters such as photovoltaic (PV) array area, number of wind machines, and battery storage capacity on the operation of hybrid (wind + solar + diesel) energy conversion systems, while satisfying a specific annual load of 41,500 kWh. The monthly average wind speeds for Dhahran range from 4.1 to 6.4 m/s. The monthly average daily values of solar radiation for Dhahran range from 3.6 to 7.96 kWh/m². Parametric analysis indicates that with two 10 kW wind machines together with three days of battery storage and photovoltaic deployment of 30 m², the diesel back-up system has to provide about 23% of the load demand. However, with elimination of battery storage, about 48% of the load needs to be provided by diesel system.     

Optimal sizing of battery storage for hybrid (wind+diesel) power systems

Hourly mean wind-speed data for the period 1986–1997 [except the years 1989 (some data is missing) and 1991 (Gulf War)] recorded at the solar radiation and meteorological monitoring station, Dhahran (26°C 32′ N, 50° 13′ E), Saudi Arabia, have been analyzed to investigate the optimum size of battery storage capacity for hybrid (wind+diesel) energy conversion systems at Dhahran. The monthly average wind speeds for Dhahran range from 4.12 to 6.42 m/s. As a case study, the hybrid system considered in the present analysis consists of two 10 kW Wind Energy Conversion Systems (WECS), together with a battery storage system and a diesel back-up. The yearly and monthly average energy generated from the above hybrid system have been presented. More importantly, the study explores the impact of variation of battery storage capacity on hybrid power generation. The results exhibit a trade-off between size of the storage capacity and diesel power to be generated to cope with specific annual load distribution [41,500], and for given energy generation from WECS. The energy to be generated from the back-up diesel generator and the number of operational hours of the diesel system to meet a specific annual electrical energy demand have also been presented. The diesel back-up system is operated at times when the power generated from WECS fails to satisfy the load and when the battery storage is depleted. The present study shows that for economic considerations, for optimum use of battery storage and for optimum operation of diesel system, storage capacity equivalent to one to three days of maximum monthly average daily demand needs to be used. It has been found that the diesel energy to be generated without any storage is considerably high; however, use of one day of battery storage reduces diesel energy generation by about 35%; also the number of hours of operation of the diesel system are reduced by about 52%.     

Promoting applications of hybrid (wind+photovoltaic+diesel+battery) power systems in hot regions

Depleting oil and gas reserves, combined with growing concerns of atmospheric pollution/degradation, have made the search for energy from renewable sources of energy, such as solar and wind, inevitable. Literature indicates that commercial/residential buildings in Saudi Arabia consume an estimated 10–40% of the total electric energy generated. In the present study, hourly mean wind-speed and solar radiation data for the period 1986–1997 recorded at the solar radiation and meteorological monitoring station, Dhahran (26°32′ N, 50°13′ E), Saudi Arabia, have been analyzed to investigate the potential of utilizing hybrid (wind+solar) energy conversion systems to meet the load requirements of a typical commercial building (with annual electrical energy demand of 620 000 kWh). The monthly average wind speeds for Dhahran range from 4.1 to 6.4 m/s. The monthly average daily values of solar radiation for Dhahran range from 3.6 kWh/m² to 7.96 kWh/m². The hybrid systems considered in the present analysis consist of different combinations of commercial 10 kW wind energy conversion systems (WECS), photovoltaic (PV) panels supplemented with battery storage unit and diesel back-up. The study shows that with 30 10-kW WECS together with 150 m² PV, and 3 days of battery storage, the diesel back-up system has to provide 17% of the load demand. However, in the absence of battery storage, about 38% of the load needs to be provided by the diesel system.     

Performance evaluation of hybrid (wind/solar/diesel) power systems

Depleting oil and gas reserves, combined with the growing concerns of global warming, have made it inevitable to seek alternative/renewable energy sources. The integration of renewables such as solar and wind energy is becoming increasingly attractive and is being used widely, for substitution of oil-produced energy, and eventually to minimize atmospheric degradation. The literature shows that commercial/residential buildings in Saudi Arabia consume an estimated 10–40% of the total electric energy generated. In the present investigation, hourly wind-speed and solar radiation measurements made at the solar radiation and meteorological monitoring station, Dhahran (26°32′ N, 50°13′ E), Saudi Arabia, have been analyzed to investigate the feasibility of using hybrid (wind+solar+diesel) energy conversion systems at Dhahran to meet the energy needs of twenty 2-bedroom houses. The monthly average wind speeds for Dhahran range from 4.1 to 6.4 m/s. The monthly average daily values of solar radiation for Dhahran range from 3.6 kWh/m² to 7.96 kWh/m². The performance of hybrid systems consisting of different rated power wind farms, photovoltaic (PV) areas, and storage capacities together with a diesel back-up are presented. The monthly average daily energy generated from the above hybrid system configuration has been presented. The deficit energy generated from the back-up diesel generator and the number of operational hours of the diesel system to meet a specific annual electrical energy demand of 702,358 kWh have also been presented.     

Prospects of autonomous/stand-alone hybrid (photo-voltaic + diesel + battery) power systems in commercial applications in hot regions

Most of the world’s energy consumption is greatly dependent on fossil fuel, which is exhaustible and is being used extensively due to continuous escalation in the world’s population and development. This valuable resource needs to be conserved and its alternatives need to be explored. In this perspective, dissemination and utilisation of renewables such as solar energy has gained worldwide momentum since the onset of oil crises of 1970s. Moreover, burning of fuels is the principal cause of air pollution, and possibly environmental warming. Saudi Arabia, being blessed with a fairly high level of solar radiation, is a suitable candidate for deployment of solar photo-voltaic (PV) panels for power generation during crisis. Literature indicates that commercial/residential buildings in Saudi Arabia consume an estimated 10–45% of the total electrical energy generated/consumed. In the present study, hourly mean solar radiation data for the period 1986–1993 recorded at the solar radiation and meteorological monitoring station, Dhahran (26° 32′ N, 50° 13′ E), Saudi Arabia, have been analyzed to investigate the potential of utilizing hybrid (PV+diesel) power systems to meet the load requirements of a typical commercial building (with an annual electrical energy demand of 620,000 kWh). The monthly average daily solar global irradiation for Dhahran ranges from 3.61 to 7.96 kWh/m². The hybrid systems considered in the present analysis consist of different combinations of PV panels/modules (different array sizes) supplemented with a battery storage unit and diesel back-up. The study shows that with a combination of 3700 m² PV together with 12 h of battery storage, the diesel back-up system has to provide 6% of the load demand. However, in the absence of a battery bank, about 56% of the load needs to be provided by the diesel system.     

Technical and economic assessment of grid-independent hybrid photovoltaic–diesel–battery power systems for commercial loads in desert environments

Solar photovoltaic (PV) hybrid system technology is a hot topic for R&D since it promises lot of challenges and opportunities for developed and developing countries. The Kingdom of Saudi Arabia (KSA) being endowed with fairly high degree of solar radiation is a potential candidate for deployment of PV systems for power generation. Literature indicates that commercial/residential buildings in KSA consume an estimated 10–45% of the total electric energy generated. In the present study, solar radiation data of Dhahran (East-Coast, KSA) have been analyzed to assess the techno-economic viability of utilizing hybrid PV–diesel–battery power systems to meet the load requirements of a typical commercial building (with annual electrical energy demand of 620,000 kW h). The monthly average daily solar global radiation ranges from 3.61 to 7.96 kW h/m². NREL's HOMER software has been used to carry out the techno-economic viability. The simulation results indicate that for a hybrid system comprising of 80 kWp PV system together with 175 kW diesel system and a battery storage of 3 h of autonomy (equivalent to 3 h of average load), the PV penetration is 26%. The cost of generating energy (COE, US$/kW h) from the above hybrid system has been found to be 0.149 $/kW h (assuming diesel fuel price of 0.1 $/L). The study exhibits that for a given hybrid configuration, the operational hours of diesel generators decrease with increase in PV capacity. The investigation also examines the effect of PV/battery penetration on COE, operational hours of diesel gensets for a given hybrid system. Emphasis has also been placed on unmet load, excess electricity generation, percentage fuel savings and reduction in carbon emissions (for different scenarios such as PV–diesel without storage, PV–diesel with storage, as compared to diesel-only situation), cost of PV–diesel–battery systems, COE of different hybrid systems, etc.     

Hybrid wind/PV/diesel hybrid power systems modeling and South American applications

This paper presents an applications case study and comparison of performance results between two computational models for simulating the performance of hybrid power systems. The first model, HYBRID2, was developed at the University of Massachusetts under National Renewable Energy Laboratory (NREL) sponsorship. The second model, SOMES, was developed at Utrecht University in the Netherlands. Both models have been designed to predict the technical and economical (life cycle cost) performance of hybrid power plants that typically might be comprised of renewable energy sources, a battery bank, and a diesel generator. A South American (Brazil) based hybrid power system used to power a remote telecommunications system was used for the applications case study. A final system configuration be used as a basis for model prediction comparison was established as a result of HYBRID2 parametric evaluation. Both codes yielded similar performance results, and this work points out that the predicted performance discrepancies are due basically to different subcomponent models and differences in control strategy. The generalized nature of this work is intended to be of interest to engineers involved with the design and analysis of hybrid power systems.     

风/光互补发电系统的优化设计

在分析现有风/光互补发电系统研究的基础上,确定风机容量与PV组件容量在系统总容量中所占的比例;根据安装地点气候条件与地理条件、负载要求,估算出蓄电池的最低容量,并归纳设计各部件的数量和类型选择的约束关系;综合给出一种适合于风/光互补发电系统优化设计的模型。     

Optimal sizing study of hybrid wind/PV/diesel power generation unit

In this paper, a methodology of sizing optimization of a stand-alone hybrid wind/PV/diesel energy system is presented. This approach makes use of a deterministic algorithm to suggest, among a list of commercially available system devices, the optimal number and type of units ensuring that the total cost of the system is minimized while guaranteeing the availability of the energy. The collection of 6 months of data of wind speed, solar radiation and ambient temperature recorded for every hour of the day were used. The mathematical modeling of the main elements of the hybrid wind/PV/diesel system is exposed showing the more relevant sizing variables. A deterministic algorithm is used to minimize the total cost of the system while guaranteeing the satisfaction of the load demand. A comparison between the total cost of the hybrid wind/PV/diesel energy system with batteries and the hybrid wind/PV/diesel energy system without batteries is presented.The reached results demonstrate the practical utility of the used sizing methodology and show the influence of the battery storage on the total cost of the hybrid system.     

A feasibility study of hybrid wind power systems for remote communities

Global warming, climate change and the recent global financial crisis have emphasised the need for reducing carbon emissions whilst also ensuring economic feasibility. This study addresses this topic by investigating the technical and economic feasibility of replacing diesel power generation with hybrid wind power systems in remote communities. For this purpose, the economic, technical and environmental characteristics of eight different hybrid wind power systems were established and compared in respect to their performance in the isolated community of French Island (Victoria, Australia). The results obtained in this study demonstrated the economic and environmental superiority of the hybrid wind–diesel–battery system over all other systems studied in this project. This system was found to have the lowest net present cost and cost per kWh among the modelled systems. Furthermore, the results clearly indicated that hybrid wind power systems are, in general, a feasible and preferable alternative to diesel power generation on the French Island. The research methodology and procedure that were developed in this project can be used to investigate and identify the most viable hybrid power system for other remote communities based on their specific environmental, social and economic circumstances.     

Impact of plug-in hybrid electric vehicles on power systems with demand response and wind power

This paper uses a new unit commitment model which can simulate the interactions among plug-in hybrid electric vehicles (PHEVs), wind power, and demand response (DR). Four PHEV charging scenarios are simulated for the Illinois power system: (1) unconstrained charging, (2) 3-hour delayed constrained charging, (3) smart charging, and (4) smart charging with DR. The PHEV charging is assumed to be optimally controlled by the system operator in the latter two scenarios, along with load shifting and shaving enabled by DR programs. The simulation results show that optimally dispatching the PHEV charging load can significantly reduce the total operating cost of the system. With DR programs in place, the operating cost can be further reduced.     

Modelling of solar/diesel/battery hybrid power systems for far-north Cameroon

Solar/diesel/battery hybrid power systems have been modelled for the electrification of typical rural households and schools in remote areas of the far north province of Cameroon. The hourly solar radiation received by latitude-titled and south-facing modules was computed from hourly global horizontal solar radiation of Garoua using Hay's anisotropic model. Using the solar radiation computed for latitude-tilted and south-facing modules, the average daytime temperatures for Garoua and parameters of selected solar modules, the monthly energy production of the solar modules was computed. It was found that BP solar modules with rated power in the range 50–180 Wp produced energy in the range 78.5–315.2 kWh/yr. The energy produced by the solar modules was used to model solar/diesel/battery hybrid power systems that could meet the energy demand of typical rural households in the range 70–300 kWh/yr. It was also found that a solar/diesel/battery hybrid power system comprising a 1440 Wp solar array and a 5 kW single-phase generator operating at a load factor of 70%, required only 136 generator h/yr to supply 2585 kWh/yr or 7 kWh/day to a typical secondary school. The renewable energy fraction obtained in all the systems evaluated was in the range 83–100%. These results show that there is a possibility to increase the access rate to electricity in the far north province without recourse to grid extension or more thermal plants in the northern grid or more independent diesel plants supplying power to remote areas of the province.     

Design requirements for medium-sized wind turbines for remote and hybrid power systems

This paper provides an overview of the design requirements for medium-sized wind turbines intended for use in a remote hybrid power system. The recommendations are based on first-hand experience acquired at the University of Massachusetts through the installation, operation, and upgrade of a 250-kW turbine on a mountain top with difficult access in Western Massachusetts. Experience with the operation of this turbine and the design of its control system, together with a long history in the design and analysis of hybrid power systems, has made it possible to extend the work in Western Massachusetts to remote or hybrid power systems in general. The University test site has many attributes of more remote sites and the overall wind turbine installation is typical of one that could power a hybrid wind system. For example, access to the site is limited due to steep terrain, snow, and environmental restrictions. Also, the power lines feeding the turbine exhibit voltage sags and phase imbalance, especially during start-up. This paper is based on the experience gained from the operation of this wind turbine and assesses the requirements for the design and operation of medium to large wind turbines in remote locations. The work summarizes lessons learned relative to: (1) sensors, communication, and control capabilities; (2) grid connection issues; and (3) weather-related problems. The final section of the paper focuses on design requirements to ensure successful installation and the completion of maintenance and repairs at remote sites.     

Techno-economic feasibility of photovoltaic,wind, diesel and hybrid electrification systems for off-grid rural electrification in Colombia

Electrification to rural and remote areas with limited or no access to grid connection is one of the most challenging issues in developing countries like Colombia. Due to the recent concerns about the global climatic change and diminishing fuel prices, searching for reliable, environmental friendly and renewable energy sources to satisfy the rising electrical energy demand has become vital. This study aims at analyzing the application of photovoltaic (PV) panels, wind turbines and diesel generators in a stand-alone hybrid power generation system for rural electrification in three off-grid villages in Colombia with different climatic characteristics. The areas have been selected according to the “Colombia’s development plan 2011–2030 for non-conventional sources of energy”. First, different combinations of wind turbine, PV, and diesel generator are modeled and optimized to determine the most energy-efficient and cost-effective configuration for each location. HOMER software has been used to perform a techno-economic feasibility of the proposed hybrid systems, taking into account net present cost, initial capital cost, and cost of energy as economic indicators.     

Cost–benefit analysis of remote hybrid wind–diesel power stations: Case study Aegean Sea islands

More than one third of world population has no direct access to interconnected electrical networks. Hence, the electrification solution usually considered is based on expensive, though often unreliable, stand-alone systems, mainly small diesel-electric generators. Hybrid wind–diesel power systems are among the most interesting and environmental friendly technological alternatives for the electrification of remote consumers, presenting also increased reliability. More precisely, a hybrid wind–diesel installation, based on an appropriate combination of a small diesel-electric generator and a micro-wind converter, offsets the significant capital cost of the wind turbine and the high operational cost of the diesel-electric generator. In this context, the present study concentrates on a detailed energy production cost analysis in order to estimate the optimum configuration of a wind–diesel-battery stand-alone system used to guarantee the energy autonomy of a typical remote consumer. Accordingly, the influence of the governing parameters—such as wind potential, capital cost, oil price, battery price and first installation cost—on the corresponding electricity production cost is investigated using the developed model. Taking into account the results obtained, hybrid wind–diesel systems may be the most cost-effective electrification solution for numerous isolated consumers located in suitable (average wind speed higher than 6.0 m/s) wind potential regions.     

考虑风电不确定性的交直流混联系统同质化能量函数模型

交直流混联电网是电网发展的新形态,如何有效保障交直流混联系统安稳运行是重大而紧迫的国家需求。文章针对含大规模风电的交直流混联系统稳定性问题,提出考虑风电波动不确定性的交直流混联弱送端系统同质化能量函数模型。首先,研究含大规模风电的交直流混联弱送端系统潮流方程;其次,建立含风电的交直流混联系统支路暂态势能函数模型,研究交直流混联系统功角稳定机理,建立基于同质化能量函数模型;在此基础上,提出基于同质化能量函数的电力系统稳定性评估模型,并推导交直流混联系统稳定性判据;最后,以北方某区域交直流混联系统为仿真算例,验证所提模型的有效性,为含大规模新能源的交直流混联系统的稳定性控制提供理论依据。     

新型混合粒子群算法在电力系统最优潮流计算中的应用

根据风速的概率分布函数和给定风速下风机的输出功率,求出风电机组的有功功率分布函数,然后对含有异步风力发电机的节点采用无功-电压模型进行潮流分析,以电力系统中的发电机容量、支路功率和静态安全电压为约束条件,建立起常规机组发电成本和风电机组惩罚成本的目标函数,提出一种新型混合粒子群算法,并结合IEEE39节点系统进行仿真,通过与传统粒子群算法进行对比,验证新算法的优越性及模型准确性。     

多形态可控负荷参与风电消纳的荷源优化模型

针对我国大规模风电消纳受阻问题,提出了多形态可控负荷参与风电消纳的荷源优化模型。文章分析了多形态可控负荷参与调节对消纳受阻风电的影响,研究了多形态可控负荷的调节特性,并建立了可调节模型。在此基础上,分别建立了多形态可控负荷参与风电消纳的日前荷源电量优化模型以及日内功率优化模型,并综合日前、日内荷源优化模型,建立了多形态可控负荷参与风电消纳的荷源优化模型。采用该模型可深入挖掘多形态可控负荷的互补调节能力,提高风电消纳水平。通过算例验证了该荷源优化模型的可行性和有效性。     

Adequacy evaluation of wind power generation systems

This paper attempts to assess the adequacy of wind power generation systems using the data collected from seven wind farms in Muppandal, Tamilnadu (India) with a total capacity of 37 MW. A Monte Carlo model simulation is incorporated in the algorithm to obtain the hourly power output of wind farms, which also takes into account the unavailability of wind turbines. A typical load demand profile is used to examine the chronological hourly wind power generation for each month. The reliability index of LOLE (loss of load expectation) is used to estimate the reliable contribution of wind farm power generation.