| At present,there are only 800 kV DC voltage ratio standards in China.If the original standards are applied directly on higher than 800 kV DC voltage transformers field calibration,the distribution of surrounding electric field is still uneven,which will lead to lower accuracy.In recent years,the design problem of DC voltage transformers above 800 kV has received more and more attention and research.When designing the 1100 kV DC voltage transformer,it is found that the grading ring can effectively improve the problem of excessive maximum electric field strength around the voltage divider,and the grading ring is widely used in UHV DC transmission.Its size and installation position directly affect the improvement of the electric field.The effect of distortion,but there is no uniform setting of the installation position and size standard of the grading ring.When determining the installation position and size of the grading ring,most of the trial and error methods are used,which may not meet the engineering requirements,corona or leakage current phenomenon.Researching and designing the 1100 kV DC resistance standard voltage divider,using orthogonal iterative test method to determine the installation position and size of the grading ring,which has a good reference for the design,manufacture and operation of the voltage divider.For UHV DC transmission Development has important practical significance.In this paper,based on ANSYS finite element simulation software,a model of ±1100kV DC resistance standard voltage divider is built,and an orthogonal-iterative test method is proposed.The standard voltage divider around ±1100kV DC resistance and the voltage equalization loop around the voltage divider are deepened.the study.First of all,this paper systematically introduces the basic structure and principle of DC resistance standard voltage divider,the numerical calculation of electromagnetic field and the basic principle of ANSYS simulation software,the basic principle and test procedure of orthogonal test method and iterative method.The DC resistance standard voltage divider plays an indispensable role in the HVDC transmission system,including energy metering,power detection,relay protection signal transmission,etc.,so the stability and accuracy of the data collected and transmitted for the grid safety and economy have an important impact;electromagnetic field numerical calculation is a mathematical algorithm based on the basic theory of electromagnetic field and computer application.The ANSYS finite element analysis and simulation software is used to build a ±1100kV DC resistance standard voltage divider model to obtain simulation results.Orthogonal experimental design is a mathematical method to obtain the best production conditions,which can find the optimal installation position and size of the grading ring efficiently and scientifically.The iterative method is a method of continuously retrieving new values with the old values of variables.process.These theories provide the basis for the design of a 1100 kV DC resistance standard voltage divider and a surrounding grading ring.Secondly,the electric field simulation analysis and scheme design of 1100 kV DC resistance standard voltage divider are carried out,and the reasons affecting the accuracy of DC resistance voltage divider are analyzed.The ANSYS finite element simulation of the electric field around the voltage divider is carried out by comparing the model.Without the simulation result of the voltage equalization loop,it is necessary to install the voltage grading ring.The ANSYS general postprocessor is used to extract the node information of the 100 electric field strengths on the measuring resistance layer to the MATLAB software,and the electric field strength on the measuring resistance layer is plotted with the height.The curve of variation and the curve of comparison show that it is very necessary to install the shielding resistance layer.It is found that the change of the parameters of the grading ring has a significant effect on the improvement of the electric field distribution by the control variable method.The difference between the parameters of the grading ring and the maximum electric field strength is not simple.Increment or decrement,the parameters are not mutually unrelated,and this conclusion lays the groundwork for the later research.Finally,this paper proposes an orthogonal-iterative test method to solve the size and installation position information of the grading ring around the 1100 kV DC resistance standard voltage divider.It can be seen from the experiment that the method can quickly determine the optimal range and direction of the installation position and size parameters of the grading ring while effectively reducing the initial electric field strength.It should have completed 729×2tests,and only need to use the orthogonal-iterative test method.By performing 27×2 tests,the optimal value can be found,which effectively reduces the number of trials and the number of iterations,and improves production efficiency.The optimal combination obtained by the orthogonal-iterative test method is substituted into the ANSYS simulation software to verify that the maximum electric field strength around the voltage divider drops from 6869.37 V/mm to 1536.24 V/mm,which improves the measurement accuracy of the voltage divider.The correctness and effectiveness of the algorithm are proved. |
