| DC high-voltage (DHV) is widely used in the industrial and agricultural production, the scientific research, the national defense construction, and people's daily life. In order to effectively control and use DHV, people need to measure it and ensure the value unified. Along with the development of HVDC and Ultra HVDC transmission project in China, the rising of the voltage level urgently requires the improving of the measuring method, the traceability system and the on-site calibration method of DHV.In view of the lack of DHV measurement standard, this paper researches the establishment of DHV measurement standard system of 500 kV and above, which can solve the problem of value traceability and dissemination for DHV value in China. As a result, the research hopefully can provide technical support for the accurate measurements of DHV, give settlement for DC power trade, and provide a basis for DC energy saving and emission reduction.DHV measurement standard system includes the precision measuring method and the study of the value traceability.In the field of the precision measurement of DHV, this paper researches the core issues of the design of the precision DHV resistance divider:the characteristics of the resistors, the thermal analysis of the divider, and the electric field simulation.First, the characteristics of the precision high-voltage resistors are analyzed, a method for determine the temperature coefficient and voltage coefficient of the resistors under the actual working condition is put forward. Second, based on the classical heat transfer theory, a heat transfer model of the divider is founded, and the heat transfer process of the resistance divider is analyzed. Also, an iterative method is proposeded to calculate the temperature distribution and the heat dissipation of the divider at thermal equilibrium. Third, a finite element model of a DHV divider is founded. A finite element software is adopted to calculate the electric field distribution of the divider and the potential distribution and electric field distribution along longitudinal direction of the measuring resistor layer.In the field of DHV traceability, this paper introduces a method for determining the ratio change of DHV dividers with the applied voltage under the actual working condition. Two auxiliary voltage dividers with the same rated voltage U were used to calibrate the voltage divider with rated voltage 2U. Experimental results showed that the measurement uncertainty of the method can achieve 1 mV/kV at an applied voltage of 100 kV. The ratio change of DHV dividers caused by the parameter changes of the resistors with applied voltage can be evaluated more accurately when compared to other existing methods.Utilizing the above research results, this paper establishes a 500 kV DHV proportion self-calibration standard system. The main organization, the screening method for resistors, the shielding structure, the assembly process, and the auxiliary equipments of the system are analyzed and introduced in detail. Experimental results showes that the expansion measurement uncertainty of the 500kV standard divider is better than 1×10-4.On the basis of the DHV high-voltage measurement standard system above, this paper further researches the on-site calibration method for HVDC project. A set of HVDC standard equipment used in converter station for on site calibration test has been developed, which is made up of a standard divider, a high-stable high-voltage power source, and a measuring system with synchronous data acquisition. The on-site calibration test for the DHV measuring equipments in±500kV and±800kV HVDC converter station are completed for the first time internationally.
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