Research Of Voltage Transformer Based On Distributed Optical Sensing Technology

Voltage transformer is an important power equipment to connect the primary equipment and the second equipment of the power system.It plays an important role in monitoring and measurement of the voltage for the power system.With the development of economy,society and the construction of intelligent substation,power system voltage level is more and more high,the transmission capacity is larger and larger.In this situation,the traditional transformer exposes some shortcomings,such as insulation,bulky volume,ferromagnetic resonance,and so on.So the traditional voltage transformer will not meet the requirement of the power system.Optical voltage transformer is a novel voltage transformer.It has been widely studied and developed quickly because of its excellent insulation performance and simple structure.Firstly,the principle and structure of various optical voltage transformers are briefly introduced,and the advantages and disadvantages of all kinds of optical voltage transformers are compared.Because the voltage transformer based on distributed optical sensing technology can solve the problems that other optical voltage transformers exist.For example,the crystal of the optical voltage transformer without divider cannot withstand overvoltage and the voltage ratio of the optical voltage transformer with divider could be affected by temperature and stray capacitance.So,the voltage transformer based on distributed optical sensing technology will be studied deeply in this paper.Optical electric field sensors are used in the voltage transformer based on distributed optical sensing technology to measure the electric field intensity of the multi points inside the optical voltage transformer cavity,and the measured values of each point are calculated numerically to obtain voltage value of the high voltage side.Therefore,the key of the optical voltage transformer is to determine the measurement point numbers,position and weighting coefficient of the measuring points.In this paper,the numerical method is used to determine the number,location and weighting coefficient of electric field sensors in optical voltage transformer,various numerical methods are simulated and compared,and the numerical method satisfying theoretical requirements is selected.Secondly,the influence of the uniform stability of the electric field intensity distribution between the two electrodes on the measurement accuracy is analyzed in this paper.Then the Ansoft Maxwell software is used to analysis electric field distribution with the different parameters of the optical crystal,the electrodes and the shielding material for the transformer.Lastly,the structure of the voltage transformer is optimized according to the results of the simulation.Finally,the measurement value of the voltage transformer based on distributed optical sensing technology is calculated after the structure optimized.The calculation results show that the output of the distributed optical voltage transformer has good accuracy and stability,and it can meet the relevant requirements.