A System Design For Accurate Measurement Of Radio Interference From High Voltage Transmission Lines

In recent years, with the increase of power capacity and voltage level, the electromagnetic effects on the environment of high voltage transmission line have been paid more and more attention. Recently, we have found that the phenomenon of radio interference exceeding the national standard is very prevalent, when we assessed environmental impact of electromagnetic radiation by the high-voltage transmission lines. And we have found the phenomenon mentioned above is because of the same frequency signal interference in the background noise present at a certain frequency measurement. However the frequency of interference is the same with the frequency of electromagnetic radiation of the measured equipment, so the same frequency signal interference could hardly be identified by measuring receiver. In this case, we can not accurately measure electromagnetic radiation of the high voltage transmission line by using the existing measurement devices. So assessing the impact of electromagnetic radiation to the environmental is very difficult.In this paper, the research on the accurate measurement system for radio interference of high voltage transmission line is carried out deeply. And the specific project is "national public service sectors of scientific research projects:Research on the technology of accurate measurement and the system of precise prediction of electromagnetic environment impact assessment". The analog dual-channel receiver is analyzed, and then the digital design of the analog dual-channel receiver is proposed. Finally, the design of software system of radio interference measurement is completed.When we use the digital dual-channel receiver to measure radio interference, the data acquisition of the two channels should be strictly synchronous, because the two receivers are not in the same position. In this paper, AD9548 produced by ADI is used for providing clock signal and sampling signal with the same frequency and phase via the GPS signal, so that the two receivers can start the data acquisition synchronously. And the wireless communication module based on ZigBee is used for data transmission.The software system is the key part of the virtual instrument. After the hardware system is determined the future, we can design the software system to realize various function of the virtual instrument. In this paper, a set of software for measurement based on Lab VIEW is designed, which includes data collection module, data storage module and data fusion module. And the software system can manage the measurement data via the technology of Access database.