The Research And Design Of Grid-connected Photovoltaic Monitoring System Based On Virtual Instrument

As a clean and renewable energy, the use of solar energy has been increased rapidly in recent years. The grid-connected photovoltaic system has become one of the main ways of using solar energy. The demands of the monitoring system are increasing with the expansion of the photovoltaic power station. The traditional monitoring system always has a complex structure, and it is difficult to modify it. Additionally, the management and application of the monitoring datas are always difficult. In order to solve these problems, this thesis designed a sophisticated monitoring system by using the virtual instrumnentation concept, which can guarantee the PV is running nomally. In addition, it can provide reliable datas for the evaluation of PV systems.The monitoring system designed has two main functions. One is monitoring the performance of the PV and another is detecting the power quality of the common coupling point(PCC).The overall strcucture of the monitoring system are designed according to the factors which impact on the performance of the PV and the influences on the power quality when the PV system connects to the grid. The CompactRIO system and the PXI seytem are choosed as the main hardware platform. The former is used to measure the following parameters:the radiation of the sun, the temperature of the panels, DC power, energy generated by the PV array, etc. Except detecting the power qulity of the PCC, the latter is responsible for the datas compilation, analysis and storage of the entire monitoring system. The CompactRIO system and the PXI seytem are designed fistly, and other acquisition equipments are optimized.Based on distributed measurement thinking, the latest FPGA prigramming techniques integrated to LabVIEW is used to develop the monitoring programs running on the front-end. The real-time datas obtained are transferred by the network communication technique. According to the international standards of power quality detection, the power quality detecting programs are developed. By the cooperation of the advanced hardware, the monitoring system achieves the online detection of power quality of the PCC.At last, SQL Server2008is choosed as a platform for the development of the database of the monitoring system. Then the problem of large dates of photovoltaic grid-connected system to store is solved. What’s more, it makes the historical datas query and the the evaluation of PV system easy and convenient.Compared with the traditional monitoring instrument, it not only has the advantages of powerful monitoring features, scalability, flexibility and short development cycle, but also meets the requirements of the contemporary monitoring system on the measurement accuracy and speed, and a friendly interactive interface is convenient for the operator to ues.