All rights reserved by SGCC P1 1 The Progress on the Electromagnetic Environment Study of UHVDC Transmission Lines in SGCC

P2 All rights reserved by SGCC Contents 1 Background 2 Summary for Electromagnetic Environment Studies in China 3 Calculation Studies on Electromagnetic Environment 4 Test Studies on Electromagnetic Environment 5 Experiment on the DC Test Line with High Altitude at Tibet 6 Study on ±800kV DC Line with Vertical Arrangement 7 Study on ±800kV DC line with Double-circuit 8 Conclusion

P3 All rights reserved by SGCC 1 Background 1)According to the actual situation in China, ±800kV UHVDC transmission lines will be adopted in the project which transmits the electricity from west to east. 2) Except the single-circuit line, double-circuit DC line on common tower will be developed, because of the limited corridor in China. 3)Some fundamental studies for corona effect on UHVDC lines were conducted in some country (e.g., the USA and Canada) last 70’s and 80’s, but there are not any transmission lines operating at ±800kV in the world. 4)±800kV DC line in China passes through areas with high altitude, and the terrain environment along the line differs greatly, so the electromagnetic environment control becomes one of the key techniques in the development of UHVDC transmission and should be solved after theoretic and test studies.

P4 All rights reserved by SGCC 1 Summary for Electromagnetic Environment Studies in China The study and construction for electromagnetic environment test facilities was beginning in 2005, including ： 1) UHVDC test line: 1) UHVDC test line: 2) DC test line with high altitude: 2) DC test line with high altitude: 3) Corona cage 3) Corona cage 4) Simulating test site for electromagnetic environment 4) Simulating test site for electromagnetic environment 5) The tank with low air pressure 5) The tank with low air pressure

P5 All rights reserved by SGCC 3 Calculation Studies on Electromagnetic Environment Electromagnetic Environment Parameters Total Electric Field at Ground （ kV/m ） Ion Current Density at Ground （ nA/m 2 ） Audible Noise （ dB （ A ）） Radio Interference （ dB （ μV/m ）） Limits 30 （ Under Line ） 15 （ Residential areas ， Wet Conductors ） 100 （ Under Line ） （ Non-Residential areas with high altitude ） 58 Tab.1 Electromagnetic environment limits for ±800kV DC line in China Tab.2 Electromagnetic environment parameter values when bundle conductor of 6  720mm 2 or 6×900mm 2 were selected Conductor pattern E MAX （ kV/m ） E SMAX （ kV/m ） J MAX （ nA/m 2 ） AN （ dB （ A ）） RI （ dB （ µ V/m ）） 6×720mm ×900mm

P6 All rights reserved by SGCC 4 Test Studies on Electromagnetic Environment Before the implementation of UHV DC project, test study on the electromagnetic environment of ±800kV DC line with bundle conductor of 6  720mm 2 has been carried out for one and a half years, by making use of the UHV DC test line in Beijing with altitude at 50m. The statistic results for the test data of total electric field at ground （ 50% value ） are shown in the following Tab.3. Tab.3 SeasonTimeNegativePositive Summer Winter Spring

P7 All rights reserved by SGCC 4 Test Studies on Electromagnetic Environment Fig.1 Test result for total electric field at different humidity Fig.2 Comparison between the calculation and test result for total electric field for conductor of moderate humidity(60 ～ 70%)

P8 All rights reserved by SGCC 4 Test Studies on Electromagnetic Environment Fig.3 Calculation and test result for transverse distribution of audible noise Fig.4 Comparison between Calculation and Test Result for RI Transverse Distribution In the test, some new phenomena were discovered.

P9 All rights reserved by SGCC 5 Experiment on the DC Test Line with High Altitude at Tibet Fig.5 Total Electric Field Fig.6 Audible Noise Fig.7 Radio Interference

P10 All rights reserved by SGCC 6 Study on ±800kV DC Line with Vertical Arrangement Fig.8 Transverse Distribution of Total Electric Field for  800kV DC Line with Vertical and Horizontal Arrangement

P11 All rights reserved by SGCC 7 Study on ±800kV DC line with Double-circuit Fig.9 Total Electric Field Fig.10 Audible Noise Fig.11 Radio Interference

P12 All rights reserved by SGCC 8 Conclusion 1) The calculation method for the electromagnetic environment of ±800kV DC line that the pole conductors are arranged horizontally or vertically, or double-circuit has been obtained in SGCC. 2) Test facilities such as UHVDC test line at Beijing, DC test line at Tibet with high altitude and corona cage and so on, provide powerful test means for electromagnetic environment study on UHVDC line. 3) The theoretical and test results indicate that, the electromagnetic environment for ±800kV DC line in China is at the same level of that for EHV DC line, and satisfies the limit requirement. 4) The electromagnetic environment of DC line is obviously influenced by the climate and altitude. The systemic theoretical and test study will be continued by using the UHVDC electromagnetic environment test facilities in China.

P13 All rights reserved by SGCC Thank You