Design Of The Real-time Monitoring System For The Small PV Stations

Photovoltaic power generation as a renewable energy becomes one of hot research atpresent. The small PV stations show a good application prospect, with the advantages oflow investment, fast construction, small footprint, strong government’s support policy andso on. However, while building PV stations，most of these don’t equip data monitoringsystem owing to the reasons of design and region. So we can’t real-timely monitor andanalyse the operation situation of stations. Aiming at the situation, this paper designs areal-time monitoring system.On the basis of photovoltaic power generation principle, this paper designs a smallphotovoltaic system at first. Take18KW stations as an example, we calculate the modeland capacity of PV module, PV battery, controller, inverter etc, and analyses the powercost and application prospect of small PV stations. And then, this paper designs thereal-time monitoring system which is based on PCI bus data acquisition card andMicrosoft Visual C++software. The general structure of the monitoring system includessolar module, PCI card, sensors, signal conversion circuit, computer, software tool etc.This system is composed of hardware and software. The hardware design mainlyincludes16bits parallel PCI acquisition card, Hall sensors, digital temperature sensor,light intensity sensor and signal conversion circuit etc. It realizes parallel signalacquisition and transmission of voltage, current, temperature and light intensity of PVstations. The software of system is designed with VC++, and uses DLL and multithreadingto apply the PCI card acquisition application program to complete the collection work.The monitoring interface provides a good man–machine interaction and couldconveniently set up parameters according to actual situation. Meanwhile, the softwareachieves the functions of signal handling, real-time digital and curve displaying, storageand inquiry etc. After debugging of this system, it begins to monitor the working conditionof PV system which is built with two25W PV module in laboratory. In the process of thissystem, we monitor one day data of PV module, and analyse the effect of temperature and light intensity. At the same time, we monitor and analyse the working condition of PVmodule for a long time. Running for a long time shows that this monitoring system is lowcost, simple operation, perfect function, high precision, stability and reliability, so it has agood practical value.