Application of photovoltaic array for pumping water as an alternative to diesel engines in Jordan Badia,Tall Hassan station: Case study

The availability of water and the ability to access are the key questions arising in developing countries including Jordan, which is the fourth poorest country in the world regarding water resources. Renewable energy, especially solar energy, can potentially play a role in the supply of safe water in Jordan Badia, where nearly 80% of the total area of Jordan is Badia, and in most cases these deep wells are far away from the national grid electricity, and in some of these areas there is an important quantity of groundwater at shallow depths. This paper introduces and compares the cost-effectiveness and the Present Value Cost (PVC) for the economic evaluation of power supply for pumping systems in remote areas in Northern Badia of Jordan by two different energy supply systems, photovoltaic systems and diesel engines.Many variables are taken into account such as the fuel prices, and the required investments. The comparison is made for a wide range of variable values, total head, tank capacity, photovoltaic array peak power and pumping requirements. A case study in Tall Hassan station is conducted to analyze the two power supply pumping systems, which are designed to supply drinking water.The results obtained are useful for choosing the best alternative for the power supply of pumping systems in wells in Northern Badia of Jordan.     

Experience with a surface floating PV pumping system: A case study in Khartoum

In a country like Sudan, where the power grid extension is limited to a small area, and fuel shortages and road inaccessibility cause major problems in providing the basic energy needs to rural areas, small scale PV systems could be a comparable application against diesel driven units. One of the main needs is water pumping for drinking, as well as irrigation purposes, so PV power pumping systems could be one of the solutions to the growing energy demand in rural areas. Such systems should ensure high reliability and low/no maintenance cost, otherwise they cannot compete with conventional systems, even in the long term. Therefore, the investigation of the field behaviour of new products is essential to characterize such designs under prevailing conditions. In this paper, a surface floating PV pumping system's performance and its technical feasibility under Khartoum's climatic conditions are investigated. Technical problems encountered with the operation of this system are clearly defined, and suggestions for design modification are advanced.     

基于新型电力系统条件下抽水蓄能电站静止变频器配置台数的优化研究

以新型电力系统发展为引,分析电网需求变化引起抽水蓄能电站发挥作用的转变,抽水及抽水调相工况将逐步代替发电工况成为抽水蓄能发挥作用的主要工况,短时间、多频次的抽水启动将成为抽水蓄能电站的主要运行方式.从抽水蓄能电站抽水启动的工作方式及原理分析,静止变频器是抽水蓄能电站抽水启动的核心设备,在新型电力系统需求变化的大背景下,...     

Sizing and modelling of photovoltaic water pumping system

With the decline in price of the photovoltaics (PVs) their use as a power source for water pumping is the most attractive solution instead of using diesel generators or electric motors driven by a grid system. In this paper, a method to design a PV pumping system is presented and discussed, which is then used to calculate the required size of the PV for an existing farm. Furthermore, the amount of carbon dioxide emissions saved by the use of PV water pumping system instead of using diesel-fuelled generators or electrical motor connected to the grid network is calculated. In addition, an experimental set-up is developed for the PV water pumping system using both DC and AC motors with batteries. The experimental tests are used to validate the developed MATLAB model. This research work demonstrates that using the PV water pumping system is not only improving the living conditions in rural areas but it is also protecting the environment and can be a cost-effective application in remote locations.     

A maximum efficiency-photovoltaic-induction motor pump system

It is not economically viable to connect remote areas to the national electric grid, so pumping systems based on photovoltaic energy sources are suitable for these areas. The induction motor is more rugged, reliable, and maintenance free than d.c. motors. In this paper, a pumping system based on an induction motor driven by a voltage source inverter is investigated. Two control strategies are considered. First, the system is controlled to operate on the maximum power line of the PV array, with variable water discharge Q. Second, the induction machine is controlled to operate at maximum efficiency. The operating characteristic of the array is thus controlled to match the voltage and current required by the motor. Comparison is carried out between the two operating schemes.     

Numerical Flow Simulation in Turbine Mode of Counter-Rotating Type Pumping Unit to Cooperate with Wind Turbine

This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind circumstance. In this paper, the tandem impellers prepared for the counter-rotating type pumping unit were operated at the turbine mode, and the performances and the flow conditions were investigated numerically with accompanying the experimental results. Even though providing the pumping unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runners/impellers of the unit work evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet, without the guide vanes. From these results, it can be concluded that this type unit is effective to work at not only the pumping but also the turbine modes.     

Mathematic models of photovoltaic motor-pump systems

Photovoltaic (PV) pumping offers the possibility of supplying water to remote and desert regions for their daily needs. The sizing of the PV pumping systems is a very significant step in order to optimize the power peak of the PV array and to ensure the best choice of the motor, the pump and the inverter. Two mathematical models were proposed in this article to contribute in the studies of PV pumping sizing. These models link directly the operating electrical power to the water flow rate of the pump versus total head. These models are based essentially on the experimentation of pumps on CDER PV pumping test facility. Two pumping systems are tested: the first uses a centrifugal pump and the second uses a positive displacement pump. The results obtained by the models are very satisfactory. Also, the models enabled us to simulate the electrical and hydraulic performances of two tested pumps. The performances are calculated using the measured meteorological data of different sites located in Sahara and coastline regions of Algeria.     

Techno-economic analysis of photovoltaic pumping system for rural water supply in Ethiopia

The diesel-driven water pumping systems have a great impact on rural water supply in Ethiopia in past decades due to the lack of access to grid electricity and associated capital intensive nature of grid expansion to rural areas. However, the requirement of diesel generator for frequent maintenance and soaring fuel cost encourages the government and concerned bodies such as NGO to go for most reliable and cost-effective alternatives. In this paper, direct coupled photovoltaic (PV) pumping system has been designed for hypothetical rural village in southern region near Arba Minch (latitude 6.02^″N, Longitude 37.54^″E) to show techno-economic feasibility of the technology. The result shows that direct coupled PV pumping system is cost-effective in terms of life cycle cost and technologically feasible for rural water supply by virtue of its very low running cost and high reliability of the component and the system as a whole.     

Low voltage ride-through strategies for doubly fed induction machine pumped storage system under grid faults

Pumped storage units bring stability to the electrical power system, so they must remain connected to the grid even during grid faults. In this paper, the authors propose efficient and simple solutions for a doubly fed induction machine pumped storage (DFIMPS) system during grid faults. In case of balanced grid faults, a control reconfiguration strategy is introduced and a hardware solution is applied in the case of unbalanced grid faults. The reconfiguration strategy consists of a commutation between different control strategies; when a balanced grid voltage fault occurs during pumping mode, the control algorithm switches to the synchronization one but based on the new grid conditions. So the proposed reconfiguration method reduces the negative impacts of grid fault occurrence on the DFIMPS system by cancelling rotor and stator over-currents and decreasing the electromagnetic torque and stator power oscillations. Simulation results carried out on a 4 kW DFIMPS system illustrate the effectiveness of the proposed approach.     

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.     

A model for optimal sizing of photovoltaic irrigation water pumping systems

The previous methods for optimal sizing of photovoltaic (PV) irrigation water pumping systems separately considered the demand for hydraulic energy and possibilities of its production from available solar energy with the PV pumping system. Unlike such methods, this work approaches the subject problem systematically, meaning that all relevant system elements and their characteristics have been analyzed: PV water pumping system, local climate, boreholes, soil, crops and method of irrigation; therefore, the objective function has been defined in an entirely new manner. The result of such approach is the new mathematical hybrid simulation optimization model for optimal sizing of PV irrigation water pumping systems, that uses dynamic programming for optimizing, while the constraints were defined by the simulation model. The model was tested on two areas in Croatia, and it has been established that this model successfully takes into consideration all characteristic values and their relations in the integrated system. The optimal nominal electric power of PV generator, obtained in the manner presented, are relatively smaller than when the usual method of sizing is used. The presented method for solving the problem has paved the way towards the general model for optimal sizing of all stand-alone PV systems that have some type of energy storage, as well as optimal sizing of PV power plant that functions together with the storage hydroelectric power plant.     

A comparison of the solar-gas and solar-electric interface

Solar energy has several distinguishing features that bear heavily upon the eventual interfacing with gas and electric utility systems. Chief among these is its intermittent or diurnal nature, which presents differing considerations and challenges for use in conjunction with gas and electric utilities.Gas utilities provide for a winter peaking by producing year-round and storing natural gas in large underground formations, principally aquifers. Electric utilities produce on demand and rely on reserve capacity to meet summer peaks. The gas production-pipeline-storage-distribution system is chemical in nature and relatively tolerant to addition of gas of varying composition and nature. Electric systems are dynamic in nature and relatively intolerant ot the introduction of off-specification energy forms, and thus require elaborate interface protection. The storability of natural gas complements the noncontinuous aspect of solar energy and makes gas-augmented solar systems attractive. These systems can, and in many cases must, be located near the end-use site. Dispersed solar systems are attractive for electrical energy production and consumption at remote locations, for example, for irrigation water pumping. Solar electric systems that are grid connected must be of sufficient magnitude to justify the interface costs with the national grid.Solar-gas systems are preferable for space and water conditioning for homes and institutional buildings. Solar-electric systems can be either dispersed or grid connected, but the scale of technology required is considerably different in these two applications.     

油田机采系统整体节能潜力分析及优化

大庆油田第八采油厂为了实现"十一五"期间将机采系统单井日耗电降低在80kW.h/d以下的目标,对全厂新投产井和老油田生产井的机采系统进行了理论计算和现场情况分析,制定并实施了有针对性的节能措施。对于新投产井,利用最佳冲程和冲次校核载荷、扭矩,优选机型及装机功率,对抽油机、电机进行优化匹配。对20个新区块采油工程方案中2272口井采取优选节能措施后,平均设计载荷和装机功率分别降低了28kN、9.8kW,平均单井日耗电由措施前的85.7kW.h/d降低至65kW.h/d,累计节电5600×104kW.h。对于老油田生产井,通过采取优化抽汲参数、加强盘根盒管理、进行抽油机节能改造等措施,并试点应用了间歇采油技术、往复式潜油泵采油技术、智能抽油装置采油技术,使全厂机采系统平均单井日耗电、吨油电耗降低到了78.3kW.h/d、58.6kW.h/t,实现了节能目标。     

抽油机井一体化节能技术在油田中应用

抽油机是目前采油生产中的主要抽油设备,同时也是油田耗能的主要设备。将抽油机一有杆泵抽油系统分为地面及井下两部分,根据抽油机井光杆功率及电网向抽油机系统输入的总电能,分析得出抽油机井地面能耗约占总能耗的30%,地下能耗约占总能耗的70%,地下能耗节能潜力较大。地下损失能量主要包括黏滞损失功率和滑动损失功率,滑动损失功率与冲程和冲次成正比,黏滞损失功率与冲程和冲次的平方成正比。在抽油机井能耗影响因素中,运行参数是易于控制的主要影响因素。因此,确定了"大泵径、长冲程、低冲次"的地面及地下一体化优化节能思路。累计实施1152井次,系统效率由优化前的26.17%提高到30.81%,节电率达15.09%,年节电1216.86×104kW.h,节约电费776.48万元,加上节约作业费用和维护费用,年获经济效益1420.28万元。     

Solar thermal heat engines for water pumping: An update

Solar thermal-driven heat engines for water pumping have been previously reviewed for some authors in the past century. However, some devices have not been treated as metal hydride-based systems or the pumping subsystems of solar thermal-driven reverse osmosis desalination systems. Following the typical classification given in the previous literature, in this work an update of the solar heat engines for water pumping based in thermodynamic methods (conventional and unconventional) is presented. Besides small remarks about systems previously quoted by other authors, new designs found in the literature are described. In general, the main characteristics of these systems is their low efficiency, low power output and, in the case of unconventional designs, its simplicity. This work in conjunction with previous review papers make up reference point for the knowledge of the use of solar thermal energy for liquid pumping purpose.     

Economic feasibility of solar pumping

Two major questions concerning the economic feasibility of solar pumping are addressed. The first of these is concerned with finding a least-cost solar system by considering the alternative use of either thermal or water storage. The second involves the determination of areas where solar energy would be economically competitive with electricity or fuel as a power source for pumping installations.A linear programming solution is developed to find the optimal combination of thermal and water storage for a solar installation. The formulation is then extended to determine a least-cost system when hybrid systems are considered. A hybrid system may incorporate a combination of solar, electric and fuel power inputs. The concept of a breakeven “critical” distance from existing infastructure for solar installations is developed, and an example problem is provided to illustrate typical values of this distance and to show its sensitivity to the base energy costs and rate of inflation for those costs. It appears that electrical pumping is probably the most economical alternative provided that electric infrastructure is located nearby. Fuel power will also be more economical than solar if there is a source of fuel near the proposed pumping site. However, solar systems may be economically competitive when considered for installation at realistic distances from existing infrastructure.     

Comparative study of power converter topologies and control strategies for the harmonic performance of variable-speed wind turbine generator systems

Power converters play a vital role in the integration of wind power into the electrical grid. Variable-speed wind turbine generator systems have a considerable interest of application for grid connection at constant frequency. In this paper, comprehensive simulation studies are carried out with three power converter topologies: matrix, two-level and multilevel. A fractional-order control strategy is studied for the variable-speed operation of wind turbine generator systems. The studies are in order to compare power converter topologies and control strategies. The studies reveal that the multilevel converter and the proposed fractional-order control strategy enable an improvement in the power quality, in comparison with the other power converters using a classical integer-order control strategy.     

Digital power factor control and reactive power regulation for grid-connected photovoltaic inverter

The overall efficiency of photovoltaic (PV) systems connected to the grid depends on the efficiency of direct current (DC) of the solar modules to alternate current (AC) inverter conversion. The requirements for inverter connection include: maximum power point, high efficiency, control power injected into the grid, high power factor and low total harmonic distortion of the currents injected into the grid. An approach to power factor control and reactive power regulation for PV systems connected to the grid using field programmable gate array (FPGA) is proposed. According to the grid demands; both the injected active and reactive powers are controlled.In this paper, a new digital control strategy for a single-phase inverter is carried out. This control strategy is based on the phase shift between the inverter output voltage and the grid voltage, and the digital sinusoidal pulse width modulation (DSPWM) patterns, in order to control the power factor for a wide range of the inverter output current and consequently the control and the regulation of the reactive power will be achieved. The advantage of the proposed control strategy is its implementation around simple digital circuits.In this work, a simulation study of this strategy has been realized using Matlab/Simulink and PSIM. In order to validate its performance, this control has been implemented in a FPGA. Experimental tests have been carried out demonstrating the viability of this control in order to control the power factor and the injected power into the grid.     

LCL filter design and robust converter side current feedback control for grid-connected Proton Exchange Membrane Fuel Cell system

Proton Exchange Membrane Fuel Cell (PEMFC) systems are environment-friendly systems that can be used as distributed power generation (DPG) system. As DPG units are usually utilized in weak power distribution systems, the grid inductance variations should be investigated during the control design stage of the grid-tied fuel cell systems. In recent years, LCL filter is broadly utilized to grid connection of DPG units, and the proper design of this filter is an important issue. In this paper, converter side current feedback (CSCF) method has been applied due to its innate damping feature to integrate PEMFC fuel cell system through LCL filter into weak power distribution system. The impact of delay should be considered as it limits the stability region of the resonance frequency of the CSCF control method especially, in the presence of wide variations of the grid inductance. Precise-tuned LCL filter design and consequently, the proper choice of the resonance frequency can remarkably affect the performance of the CSCF control. An adequate-tuned design procedure for LCL filter parameters has been proposed in this paper. Step-by-step tuning of the PR controller parameters has also been included to enhance the power quality. The grid-tied fuel cell system with modified-Y-Source inverter and LCL filter as an interface between inverter and grid has been simulated to analyze the quality of the injected power. Simulation results in MATLAB/Simulink environment verify the suitable performance of the proposed power conditioning system as well as its stable operation versus wide variation of weak grid inductance.     

基于水库大坝的水能与太阳能融合型并网发电系统研究与应用

针对中国大中型面南的水库电站大坝,向光性比较好,具备安装太阳能光伏发电系统的条件,并使得2种可再生能源融合并网发电模式具有一定的创新性.水库电站的发电系统是已建成的,增加太阳能光伏发电系统并建设融合型并网发电系统,不仅体现了投资成本低发电效益高等特点,同时具有节约国土资源、保护大坝和节能减排等社会效益.在设计和实践过程...