Design and application of laser pulse circuit of OTDR system in smart substation
ZHANG Lingzhi
(Department of Electronic and Electrical, Hunan Vocational College of Railway Technology, Zhuzhou 412000, China)
 

Abstract: Aiming at the problem of optical fiber communication delay measurement in smart substation, the working principle of OTDR and the light source device were studied. The influence of laser pulse frequency and pulse width on the system performance was analyzed. According to the laser diode luminescence mechanism and characteristics, a set control unit based on STM32 for intelligent substation in OTDR work of laser driver circuit was desighed, focusing on analysis of the modulation current driving circuit, taking into account the driving circuit of laser protection, and the design of laser driving circuit to build simple OTDR fiber loss characteristics were observed. The research results show that the circuit can expand the adjustment range of laser pulse frequency and pulse width, achieve the minimum laser pulse width up to 300 ns, the maximum pulse frequency up to 50 kHz, the laser power up to 3 mW. Through the experiment, the attenuation characteristic of the optical fiber is verified, and it is proved that the circuit can meet the requirements of the OTDR in the actual intelligent substation, and it has a certain reference value.
Key words: OTDR; optic fiber communication; laser diode; driver circuit; laser pulse; smart substationn