基于最大功率点与最小损耗点跟踪的光伏水泵系统效率优化

    Efficiency optimization of stand-alone photovoltaic pumping system based on MPPT and MLPT

    • 摘要: 太阳能光伏电源是一种非常有潜力的再生能源,但应用成本高、投资回报率低是当前制约独立光伏水泵系统在光照充足的农村地区大面积推广的瓶颈之一。该文研究工作的核心是优化光伏水泵系统、提升效率,在不增加硬件投入的前提下,一是利用一种最大功率点跟踪(maximum power point tracking,MPPT)算法优化光伏转换效率,二是在异步电动机的损耗方面优化进而提升效率,利用一种最小损耗点跟踪(minimum loss point tracking, MLPT)算法提高水泵用异步电动机效率,并且将MPPT与MLPT耦合。通过样机试验验证了优化策略的实际运行情况,其节能效果具有一定的实际意义,从而可有效提高投资回报率。

       

      Abstract: Abstract: Solar power is a very promising global source of renewable energy, and is being used more widely throughout the world. Pumps are used for agricultural irrigation, drinking water, and other necessary pumping requirements in the vast rural area. In many places, where there is much land but few people, power is not easy to attain. In order to reach the deep groundwater, water pumps cannot rely on electric energy consumption, but instead must rely on diesel engines and traditional fuel equipment. However, we know that these regions, especially in arid areas, are rich in solar energy resources. Independent photovoltaic pump systems have emerged as a result. Although this kind of system is an application or extension currently used systems, the high cost of application and the low rate of return on investment are constraints that bottleneck the popularization of bringing independent photovoltaic pump systems to large rural areas. Therefore, the core of this paper studies the optimization of photovoltaic pump systems to enhance efficiency and to improve the rate of return on investment. Specifically, and without increasing the hardware investment, two methods are discussed. The first is the use of a Maximum Power Point Tracking (MPPT) algorithm to optimize the solar photovoltaic conversion efficiency. The second is reducing loss and enhancing the efficiency in the asynchronous motor of driving pump by using a Minimum Loss Point Tracking (MLPT) algorithm. Under different conditions, these algorithms can track motor-loss minimization real time. The study put forward anintegrated algorithm with MPPT and MLPT in a single application. MLPT is in the inner ring of integrated control system, with MPPT in the outer ring. The MPPT algorithm of the solar array, through the influence of a DC voltage inverter, output the reference frequency value, while the MLPT algorithm was based on minimizing the current control in the stator voltage to reduce asynchronous motor loss. Through a set of prototypes, first the MPPT and MLPT algorithms were tested individually. Then, according to the different light trends, the researchers tested an integrated MPPT/MLPT optimization algorithm. Using LabVIEW software, they rendered mutual relations and trend curves for each parameter. The test results show that, in a full common load case section n, the power pumping capacity increased up to 10%. This shows that photovoltaic pumping systems can effectively improve the rate of return on investment. The new system did not significantly increase investment in hardware, nor did it increase the monitoring system workload. In addition, its advantages include strong robustness, modular capabilities, and no battery storage as is commonly used in the industry. This promotes the popularity of the system as a viable long-term option. The system not only can be used in view of our poverty-stricken rural western country, but also may strengthen China's ability to develop remote rural drinking water projects in the developing country.

       

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