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Deng X.,Zhejiang University | Wang D.,Zhejiang University | Shen Y.,Hangzhou Electric Power | Zhou H.,Zhejiang University | And 2 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2014

The mechanism of switching overvoltage occurred in the valve hall and DC switchyard of ±1100kV UHVDC converter station is analyzed based on Zhundong-Sichuan ±1100 kV UHVDC power transmission project. Different faults are simulated, such as the grounding fault of HV winding of Y/Y converter transformer at valve side, the grounding fault of LV winding of Y/Y converter transformer at valve side, the phase-to-phase switching surge at AC side, the AC power loss at inverter side, the full-voltage starting, the inverter blocking without by-pass de-blocking, and the corresponding overvoltages exerted on the equipments of converter station are calculated, which provide the reference for the type selection, test and insulation coordination of station equipments. Source


Deng X.,Zhejiang University | Wang D.,Zhejiang University | Shen Y.,Hangzhou Electric Power | Zhou H.,Zhejiang University | And 2 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2014

The main circuit parameters are designed based on the DC transmission theory and characteristics of UHVDC transmission system for Zhundong-Sichuan ±1100 kV UHVDC transmission project. The basic parameters of key equipments are given and the wiring scheme of two twelve-pulse converters connecting in series is suggested. Research results show that, the maximum DC operating voltage is 1112 kV, the maximum DC is 5.357 kA, the minimum DC is 0.44 kA. The short circuit impedance of converter transformer is taken as 24% for both ends of transmission line;the rated capacity of converter transformer at rectifier station is 542.11 MV·A and that at inverter station is 521.59 MV·A;the transformer tap position of rectifier and inviter stations is +28/4 and +20/5 respectively;the reactive power consumption of rectifier and inverter stations is 6916 Mvar and 6693 Mvar respectively under rated power operation. Source


Deng X.,Zhejiang University | Wang D.-J.,Zhejiang University | Shen Y.,Hangzhou Electric Power | Chen X.-L.,Zhejiang Cixi Power Supply Bureau | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

Zhoushan multi-terminal VSC-HVDC project will be the first DC transmission project with five converter stations in the world which is based on modular multilevel converter (MMC) technology. To study the overvoltage of each converter station, overvoltage mechanism of AC and DC switchyard are analyzed in detail based on this project, and overvoltage levels in typical faults such as single-phase-to-ground fault at the valve side of converter transformer and at the valve side of converter reactor, DC pole line ground fault, ground fault at the valve side of DC smoothing reactor and DC to DC pole line fault are calculated based on the MMC-HVDC model with five stations. Results show that the maximum overvoltage for AC bus at the valve side of converter transformer is 360 kV; the maximum overvoltage for DC bus at the line side and at the valve side of the DC smoothing reactor are 370 kV and 369 kV respectively; the maximum overvoltage of the neutral point of star reactance grounded branch and converter reactor are 188 kV and 235 kV respectively; the maximum energy of arrester CB and D are 1.258 MJ and 1.655 MJ respectively. The research results will provide important basis for the insulation coordination of station devices. Source


Zhou H.,Zhejiang University | Deng X.,Zhejiang University | Wang D.,Zhejiang University | Shen Y.,Hangzhou Electric Power | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2013

In order to specify the overvoltage and insulation level of equipments in ±1100 kV UHVDC converter stations, the arrester configuration scheme and some basic parameters for ±1100 kV Zhundong converter station are proposed. Overvoltage of equipments in AC system, valve hall, DC busbar, and neutral busbar are also calculated in accordance with the fundamental principles of arrester configuration for UHV converter stations and the existing experiences in insulation coordination of ±800 kV UHVDC converter stations. The work is done also for specifing insulation levels for ±1100 kV UHVDC converter stations of the ±1100 kV UHVDC power transmission project from Zhundong to Sichuan in China. Thus, the recommended insulation margins that determine the insulation levels of converter station equipments are proposed: the insulation margins for thyristor valves are 10%/10%/15% for switching impulse/lightning impulse/steer front impulse; the insulation levels of lighting and swtiching impulses are recommended as 2600 kV and 2150 kV respectively for 1100 kV DC buses, and as 2250 kV and 2100 kV respectively for equipments at the valve side of high-voltage Y/Y converter transformers. Source

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