Analysis And Application Of Analog Photoelectric Current Transformer

Due to its advantages of simple insulation structure,small size,wide dynamic range and frequency response range,electronic current transformers have gradually replaced traditional electromagnetic current transformers as the key equipment for electrical measurement and protection.At present,the researches on active electronic current transformers are mostly based on digital optical signal transmission mode,while the researches on analog photoelectric current transformers based on analog optical signal transmission mode are less.On the basis of introducing the system composition of analog photoelectric current transformer,this paper explains the principle of analog light transmission,primary sensor and basic theory of optical fiber transmission,which provides theoretical basis for the design of analog photoelectric current transformer.In this paper,the transmission characteristics of the three parts of the system are modeled and analyzed,including the electric-optical conversion,optical fiber transmission and photoelectric conversion.The analysis results show that the LED has a long linear region that can be used for signal transmission,the attenuation of the optical power of the plastic fiber is linear attenuation,and the photodiode can realize linear photoelectric conversion under zero bias photovoltaic mode,which verifies the feasibility of transmitting signals in the analog optical signal transmission system.Due to simulate the dc reference signal light signal transmission system is introduced as a scale signal,so the simulating light signal transmission system modeling,on the basis of analysis of the use of the dc signal as a reference for simulating the influence of the optical signal transmission accuracy,can introduce calculation error found using dc signal as a reference,but with the increase of dc reference signal,calculation error decreases gradually,thus increasing the dc reference signals can effectively improve the measurement accuracy.Photoelectric current transformer of the simulation waveform change,the transmission accuracy,frequency characteristic and temperature characteristic and accuracy of the overall performance analysis,using data acquisition card and the Lab VIEW builds the simulating photoelectric current transformer test system,completed the performance for the photoelectric current transformer simulation test,the test results show that the transformer can meet the electronic transformer of measuring 0.5 on the Richter scale accuracy requirement,and has good frequency characteristic and temperature stability.Finally,the suspended prototype of the simulated photoelectric current transformer is used in the selection of the fault line of small current ground fault.The fault line selection using the signals collected by the prototype shows good results,and the practical engineering value of the simulated photoelectric current transformer is verified.