| Arrester is one of the most important apparatus in electrical equipment over-voltage protection in the running power grid.For the reason that Metal Oxide Arrester(MOA) has very good voltage protection characteristics,it's widely used in power system,thus,diagnosing the resistive current for MOA is of great importance.However, the two factors that are phase coupling capacitance and voltage harmonic seriously interference the accuracy of the measurement, a further study on designing the apparatus for testing the MOA's resistive current needs to be taken into effect. The main works in this study include:Firstly,the theory and main methods for MOA current measurement were introduced, and the advantages and disadvantages of various measurement methods were analized.Secondly,a new MOA resistive current measurement method is presented based on the zero crossing point of voltage, and mathematic deduces were also done while the voltage is normal or the third-harmonic appears.Thirdly,a simulation model is established by MATLAB Simulink for simulating the test of the MOA resistive current under normal voltage or third-harmonics.Vertilized by simulation,it is confirmed that this method designed for measuring the resistive current is of accuracy,reliable and effective.Eventually,according to the neccecery for measurement in this study, the hardware circuit and the flow chart of software were also designed. Moreover, the testing of resistive current while the equivalent capacitance of three phase zinc oxide arrester is different was also simuated by MATLAB Simulink, This results also give certificates that this method is of highly effective and accurant. |
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