光伏水泵系统控制方案及其稳定性对比分析

由于光伏阵列的I-V非线性特征,在光伏水泵系统中,驱动电机的控制方式、调节器参数及不同阵列工作点均会改变系统的传递函数结构和参数,进而影响光伏水泵系统的稳定运行。通过建立光伏水泵系统的小信号模型,详细分析系统在光伏阵列不同工作点条件下小信号模型参数的变化规律及稳定性,分别研究和对比V/F控制与矢量控制方式对系统稳定性的影响。理论分析和实验结果表明不同的控制方式对系统的稳定裕度影响差别较大,矢量控制具有快速的功率响应特性,可明显改善系统的稳定裕度。     

基于空间矢量PWM法的光伏水泵变频控制系统

介绍一种基于空间矢量PWM控制的光伏水泵变频控制系统。该空间矢量PWM算法具有对光伏阵列母线电压的动态补偿功能，保证在光伏阵列工作电压大范围变化条件下，变频驱动电机满足恒磁通调速控制。同时结合光伏水泵系统的工作特点，提出了一种简单实用的光伏阵列最大功率点跟踪控制方式，稳定可靠地实现了系统的最大功率点跟踪控制。     

数字式太阳电池阵列模拟器

阐述了新近发展的以工程用太阳电池数学模型，专用控制软件和电力电子技术为基础的数字太阳电池阵列模拟器。实验表明，该种模拟器性能良好，可以在实验室复现10kWp以下不同功率太阳电池阵列在不同日射强度、环境温度下的特性，并在屏幕上显示出被模拟阵列的I－V及P－V曲线，以闪烁光标显示该阵列在设定日射强度和环境温度下最大功率的位置及其量值，同时也以闪烁光标指标系统的工作点位置，研究操作人员可以清晰地观察到二者之间的差异。该种模拟器可以方便地引导系统研究人员分析系统运行存在的问题，从而使系统工作于最佳状态，它为光伏系统工作者及光伏系统生产厂商提供了系统优化配置的有效手段。     

基于转速观察反馈实现MPPT的光伏水泵系统

介绍了一种基于直流无刷电机的光伏水泵系统的工作原理和采用转速观察反馈实现最大功率跟踪的控制思想及程序流程图，并给出了样机在光伏阵列模拟器上的运行结果，最后分析系统的跟踪误差、DG-DC变换的选择及系统太阳电池配置方案。‘     

一种光伏发电系统的柔性功率输出控制策略北大核心CSCD

从功率供需平衡角度出发,深入研究了基于有功备用的光伏发电系统稳定运行控制策略,提出一种光伏发电系统柔性功率点跟踪(FPPT)控制策略。当光伏阵列输出功率发生波动时,按照负荷或调度功率需求进行功率匹配,使光伏阵列始终运行在稳定区域,改善无储能光伏虚拟同步发电机运行特性。基于RT-LAB实时仿真实验平台搭建了两级式光伏发电系统模型,DC/DC控制环节采用文章所提出的FPPT控制策略,DC/AC环节采用经典的VSG控制策略,实时仿真实验结果验证了所提出控制方法的正确性与有效性。     

直流微网中PV发电系统的改进型恒压控制策略

直流微网中光伏(PV)系统的控制策略会影响整个微网稳定性能。当微网中出现功率冗余时,需要减少PV系统的发电功率,PV系统需从最大功率点跟踪(MPPT)工作模式切换到限功率(非MPPT)工作模式。目前常用的限功率工作模式为恒压控制,但恒压控制稳定性差,对光伏P-U特性曲线上一些区段工作点不能稳定控制。由此该文提出改进型恒压控制,能对光伏P-U特性曲线上的所有工作点稳定控制。在Matlab/Simulink软件上仿真PV系统独立运行时和PV系统在微网中运行时的稳定性,仿真结果验证本文所提的改进型恒压控制可解决恒压控制存在的问题。     

并网光伏发电系统暂态特性研究

基于光伏发电系统的物理模型研究,在matlab/simulink中开发了包含光伏阵列模型、光伏阵列的最大功率跟踪（MPPT）模块、DC/DC升压电路和采用电压及电流环控制的逆变系统在内的动态仿真模型,并建立了基于电压型逆变器的暂态数学模型;并通过仿真得到了并网光伏发电系统辐射强度突变和发生短路时的暂态运行特性,为深入研究并网光伏发电系统的暂态特性建立了基础。     

带有蓄电池的光伏系统的优化配置实用方法

该文介绍了带蓄电池的光伏系统的最佳参数配置的简便计算方法。按照这种方法配置光伏阵列的最大功率点电压及电流，可省去最大功率跟踪器，提高系统运行效率及运行可靠性。     

太阳能光伏-PEM水电解制氢直接耦合系统优化

利用水电解制氢进行氢储能是我国可再生能源弃电问题的解决方案之一。本文建立了太阳能光伏阵列与质子交换膜（proton exchange membrane, PEM）水电解直接耦合系统的分析模型,研究耦合系统优化运行工况。结果表明,天气变化易导致直接耦合系统工作点偏离光伏最大功率点,引起耦合失配并降低太阳能利用率。通过匹配太阳能光伏阵列串并联结构和水电解器工作槽数进行“粗调”,改变PEM水电解器工作温度进行“精调”,可使直接耦合系统工作在最大功率点附近,使系统能量损失最小。本研究为太阳能光伏-PEM水电解氢储能直接耦合技术的运行策略和优化奠定了理论基础。     

光伏水泵系统中CVT及MPPT的控制比较

光伏阵列的最大功率点跟踪器可使光伏消耗产系统获得实时的最大功率输出。出于方便及降低系统造价，世界上大多数国家的光伏水泵系统产品迄今仍采用恒定电压跟踪器，以代替真正的最大功率点跟踪器。本文通过计算机仿真进一步阐明了ＣＶＴ与ＭＰＰＴ的区别并证明ＭＰＰＴ的在很大程度上优于ＣＶＴ，特别是对于冬，夏及全日内温差较大的场合。     

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.     

The effects of nominal power of array and system head on the operation of photovoltaic water pumping set with array surface covered by a film of water

The main problem in using photovoltaic (PV) systems is the low energy conversion efficiency of PV cells. The efficiency of PV cells will decrease significantly as the temperature of the cells exceed to a certain limit. In order to increase the efficiency, it is necessary to reduce the operating temperature of array. One of the ways for improving the system operation is cooling PV cells with a thin film of water. The aim of this research is to study the effects of nominal power of array and system head on the operation of system by using this method. For this purpose, a photovoltaic water pumping system is installed in Kerman city (Latitude: 30 ° 17′ and longitude: 57 ° 50′) and different methods examined to reduce PV cells temperature. The most effective way was chosen and used in set. This method is based on providing water for cooling cells by the pump itself. Experiments show that with decreasing of array nominal power and increasing in system head, the power generated by the array increases significantly. This increases the panel and total efficiency and therefore the pump flow rate. This method is ineffective as the array nominal power increases significantly.     

Direct coupling of photovoltaic power source to water pumping system

Direct coupling between a photovoltaic (PV) solar panel and a water pumping system driven by a permanent magnet dc motor is analyzed theoretically. The analysis is based on the simulated performance of a pumping system which consists of a Jacuzzi general purpose pump and a permanent magnet dc motor with selected characteristics. Hourly insolation data obtained from typical meteorological year SOLMET data are used in the simulation. A comparison between systems with and without a PV peak-power point tracker shows that a PV pumping system with peak-power tracker is more desirable because of its higher efficiency.     

Time dependent model of a complex PV water pumping system

A complex time-dependent solar water pumping system is analysed in this paper. Several existing models (e.g. for the PV cell, the battery and the assembly electric motor—centrifugal pump) are used. New models are proposed for PV array and water storage tank operation. The system has two main operating modes, which depend on the level of the incident solar global irradiance. The mathematical model consists of systems of eight or five ordinary differential equations, as a function of the operating mode. Using a water storage tank improves the stability of PV pumping system operation. The mechanical power stored in the water tank is rather constant during the year. The fraction of collected solar energy that is stored in the water’s gravitational energy is higher during the winter months, during the cloudy days and around sunrise and sunset. It is smaller during the summer months, during the clear sky days and in the middle of the day. The fraction of the power supplied by the battery that is stored in the gravitational energy of water is almost constant during the year.     

Influence of pumping head, insolation and PV array size on PV water pumping system performance

A transient simulation model, using TRNSYS, for AC photovoltaic (PV) water pumping systems is developed and validated against laboratory and field data. Simulations and analysis were undertaken in this work to: (i) discern the influence of mismatch of pump characteristics and well system characteristics on system performance; (ii) obtain average efficiencies and average performance ratios for system, subsystem and PV array over any period of time and under different operating conditions; (iii) analyze the effect of insolation frequency distribution on system performance and (iv) determining the optimum PV array size considering life cycle cost analyses. Simulation and analyses are illustrated using a real case study and utilizing real field data obtained from a system installed in Jordan.     

基于电压预估法的光伏发电系统MPPT算法

光伏发电系统处于复杂光照条件下时,光伏电池阵列的输出特性呈多峰现象,致使传统的MPPT算法追踪结果可能停留在次优点。针对此问题,提出一种基于电压预估法的光伏发电系统MPPT算法,采用DMPPT电路结构的光伏阵列,通过研究其输出特性,得到复杂光照条件下光伏阵列最大功率点对应的工作电压最佳区域,并以该预估到的电压值为基础,设计了一种新型的MPPT控制算法。仿真结果表明,所提算法能有效避免光伏系统工作在次优点,提高了光伏发电的出力。     

Techno-economic analysis and modelling of a remote photovoltaic water pumping system in the desert of Tunisia

For estimating the performance of a photovoltaic (PV) water pumping system without battery storage, a simple algorithm has been developed. This simulation program uses the hourly global solar radiation, the hourly ambient temperature and the hourly wind speed as the input, moreover the characteristics of region (latitude, longitude, ground albedo) and characteristics of PV water pumping system (orientation, inclination, nominal PV module efficiency, NOCT, PV array area, PV temperature coefficient, miscellaneous power conditioning losses, miscellaneous PV array losses, temperature of reference, moto-pump efficiency and inverter efficiency). This work allows evaluating the economic interest of a remote PV water pumping systems in the desert of Southern Tunisia, which will have to satisfy an average daily volume of 45 m³ throughout the year compared to another very widespread energy system in the area, the diesel genset (DG), by using the method of the life-cycle cost (LCC). The cost per m³ of water was calculated for this system. It is found that the LCC for PV system is 0.500 TND/m³ and the LCC DG is 0.837 TND/m³. The present study indicates economic viability of PV water pumping systems in the desert of Tunisia.     

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.     

太阳能光伏系统MPPT控制算法的对比研究

根据光伏太阳电池板的内部结构和输出伏安特性建立光伏方阵的Matlab仿真模型,利用实测的气象光强数据对恒压跟踪法、爬山法、爬山改进法和INC法等4种光伏系统最大功率跟踪(MPPT)控制算法进行计算机仿真,评价每种算法在不同天气的光照变化条件下特别是光照强度迅速变化时的跟踪效果,得出各个算法的优缺点。仿真结果用于指导太阳能光伏系统最大功率跟踪器的设计及其控制算法的选择。