| The voltage transformer plays an important role in the aspects of measurement,protection and condition monitoring of the electric power system.With the development of the electric power system,the voltage level and the power level of the power grid are also increasing rapidly.At present,the capacitive voltage transformer is the main high voltage measurement equipment used in the power grid with the voltage level of 220 kV and above.The high voltage arm capacitor of the traditional capacitive voltage transformer is composed of many capacitors in series.In the traditional capacitive voltage transformer with the rated voltage of 220 kV,the high voltage arm capacitor is composed of several hundred capacitors in series.The complex structure would cause the traditional voltage tansformer to occupy a large space,require high measurement cost and it may even lead to serious insulation problems.In addition,the traditional voltage transformer would lead to more energy loss and increase carbon emissions,which is not conducive to sustainable development.Therefore,a high voltage measurement method with simple structure,small required space,low measurement cost and reliable measurement results has an important application in the power system.In this dissertation,a new high voltage measurement method based on slice electrode method is proposed and applied to gas insulated switchgear (GIS).The basic principle of the proposed high voltage measurement method is analyzed according to Maxwell’s equations.The equivalent circuit is established according to the Gauss flux theorem and Ampere circuital theorem,and the transfer relation of the voltage measurement system is obtained according to the equivalent circuit.The simulation study on the voltage measurement system is conducted based on the electrostatic field finite element method and the field-circuit coupling method.In the simulation study,the equivalent circuit parameters are calculated,the influence mechanism of the measurement method is analyzed,the relative uncertainty of the measurement system is studied,the anti-electromagnetic interference performance of the measurement system is analyzed,the insulation gap moisture proof problem is studied,and the feasibility of the measurement method is verified theoretically.In this dissertation,the experimental platform is set up in the laboratory and the measurement experiment is carried out.In the experiment,the transfer relation of the measurement system is obtained,the measurement uncertainties are analyzed,the uncertainty of the equivalent capacitance parameters of the voltage measurement system is evaluated,the measurement accuracy of the voltage measurement system is studied.The reliability of the proposed measurement method is verified by experiment.The voltage measurement system is designed and tested on the actual GIS platform to further verify the accuracy and the feasibility of the measurement method.The voltage measurement method proposed in this dissertation has the advantages of simple structure,small required space,low measurement cost and reliable measurement results.The proposed measurement method is suitable for high voltage measurement in the power system.And it is of great significance to the measurement,protection and condition monitoring of power system. |
