Research And Application Of Carrier Communication Technology In Monitoring System Of Photovoltaic Power Station

The development of renewable new energy has become increasingly urgent as the continuous decrease of traditional energy sources and serious environmental pollution. Photovoltaic power generation has become the focus of attention due to its features of widespread, long-term and no pollution. However, it is a very large project to set up the monitoring communication network for photovoltaic power station alone since it is generally constructed in the remote areas and the scale is very large resulting in the inconvenience of information collecting and equipment maintenance. Thus it’s necessary to build a monitoring system for photovoltaic power station with the advantages of low cost, easy to maintain and convenient to control.In this dissertation, a photovoltaic power monitoring communication system which used power line carrier communication technology to realize the communication was developed. The real-time, reliable, orderly communication was ensured by the data information transmission using power lines between the field acquisition control devices and the concentrator and setting communication protocol based on LonWorks. The most important feature of power line carrier communication technology is to realize the communication using the existing power line instead of wiring again, which saves the investment in the construction of power station communication network and enlarge the monitoring scope to cover the entire power station, that is the communication can be realized where there is a power line. Meanwhile, as one of the most widely used fieldbus technologies in the field of power line carrier communication, LonWorks fieldbus technology achieves the openness and interoperability of the monitoring communication system by using the LonTalk protocol which follows the ISO/OSI seven layer model. The main jobs in this dissertation are showed as follows.(1) The technology of photovoltaic power generation and the structure of the photovoltaic power generation system were studied. The parameters needed to be collected in the site were analyzed.(2) Other kinds of communication methods and fieldbus technologies were compared. Then the power line carrier communication and LonWorks technology were selected to design the photovoltaic power station monitoring communication system.(3) The transmission characteristics of the photovoltaic power station channel were analyzed. A 2FSK modulation demodulation system based on DSTFT was designed to solve the problems of photovoltaic power station channel such as time-varying, large attenuation and large noise, thus the highly reliable communication was realized.(4) The communication between concentrator and field acquisition control equipment was realized through the power carrier modem which was fabricated using PIC32MX series chip of Microchip company. The implementation process was divided into two steps including the hardware part and the software part. The former was mainly made up of sending circuit, receiving circuit, coupling circuit, model chip and serial interface circuit, while the latter was mainly constituted of 2FSK modulation, demodulation, serial interface driver and the protocol based on the seven layer LonTalk protocol.(5) The communication performance was tested in a laboratory after the completion of the prototype production. The results showed that the communication demand in a power line channel was met by the design in this dissertation.