The Frequency Characteristic Of Optical Voltage Transformer And Its Harmonic Measurement

OVT(Optical Voltage Transformer)is an important equipment to monitor the running state of the new generation intelligent substation,but it is still focused on the measurement and application of fundamental and low harmonics.With the increase of nonlinear load in power system,harmonic pollution becomes more and more serious.The traditional electromagnetic transformer has been unab le to meet the demand of the measurement.Therefore,it is of great significance t o study the OVT for harmonic measurement.In this paper,the frequency characteristic and harmonic measurement of OVT is studied by means of simulation and experiment.Firstly,the basic structure and working principle of the OVT based on Pockles effect are analyzed in detail.On this basis,using MATLAB software to complete the simulation of the OVT simulation modeling,realize the OVT real-time dynamic simulation.Secondly,I build a test platform of frequency characteristic of OVT.The frequency characteristic of the OVT is obtained by the test.On the one hand,the simulation results are verified;on the other hand,the simulation results are complementary to each other.And then,the noise effect of OVT frequency characteristics have been analyzed.The related rule of frequency aliasing of OVT noise has been got.I also found that the sampling time and the sampling rate has significant effect on the magnitude of noise,make the rule of noise amplitude envelope with the sampling rate and sampling time clear.The effect of OVT frequency characteristics of the cumulative average link are analyzed,and the necessity for the cumulative average has been pointed out.In the case to satisfy the precision requirements,the reasonable cumulative average output points can be obtained.Finally,combined with the actual situation of the power grid,such as frequency fluctuation,voltage deviation and fluctuation,the error analysis of the measurement of the OVT is carried out.In the measurement range and accuracy,when determining the reasonable cumulative average output points,reasonable sampling rate,reasonable sampling time,the use of reasonable algorithm,using OVT to measure fundamental and harmonic of gird is feasible.