Rao Hong

Research and Application of DC De–Icing Technology in China Southern Power Grid

Ice-clad transmission lines can seriously damage a power grid, causing a partial or entire breakdown. De-icing the transmission line is a good method to prevent recurrence of such a situation. The development of dc de-icing technology can make difference in power grids preventing an ice disaster. Based on the calculation, analysis, and tests in the artificial climate chamber of the conductor de-icing parameters, the dc de-icing technical scheme for the typical transmission lines at various voltage levels in China Southern Power Grid is proposed. Two economical and practical topological structures of the dc de-icer have been proposed, and the prototypes have been developed and tested in the field successfully. Then, the defensive strategy of the power grid for ice disaster based on dc dicers is proposed. The application during the icing season of 2009-2012 in China shows that the dc de-icing method is an effective means to prevent an ice disaster in the power grid.

Development of ± 800kV UHVDC Transmission Technology in China

This paper introduces the facing technical challenges and up to date research achievement of ± 800 kV UHVDC transmission technology in China. The insulation coordination technology, external insulation technology, internal insulation technology and development of major ± 800 kV UHVDC equipments are introduced emphatically. Most of these research items to be done are the first time in the world. These research achievements presented here are very important for designing and construction of ± 800 kV UHVDC transmission project.

Study on Pollution Flashover Characteristics of ±800kV DC Composite Insulators

This paper presents the basic structure parameters of 800kV DC composite insulator specimen and the pollution test scheme. The condition of 800kV DC composite insulator pollution test under whole 800kV voltage and whole structure dimension completed in STRI, which is completed first time in the world, is introduced. The study results indicate that the linear relation between the pollution flashover voltage and the length of 800kVDC composite insulator is high-blooded. The consistency of test data between STRI and China lab is good. The pollution flashover characteristics of I string and V string under whole voltage and whole structure dimension is confirmed. The formula of DC pollution flashover grads calculated by SDD of DC composite insulator is obtained.

Fault ride-through control and its impacts on wind generators in a VSC-HVDC system

In the background of Voltage Source Converter HVDC (VSC-HVDC) gradually coming into practice, fault ride-through control for wind farm connected to a VSC-HVDC system can maintain system stability, but also impact on the wind generators. To study on fault ride-through problem for wind generators in a VSC-HVDC system, this paper establishes a simulation model of two-terminal VSC-HVDC system including detailed model of wind farm with squirrel-cage induction generators (SCIG) or doubly-fed induction generators (DFIG) in PSCAD/EMTDC, and verifies frequency increase and voltage reduction fault ride-through method for wind farm connected to a VSC-HVDC system. Furthermore, the paper studies performances of different kinds of wind generators with different fault ride-through methods, thus drawing the law of impacts of fault ride-through control on wind generators. The conclusions can provide different kinds of wind generators in a VSC-HVDC system with operation reference for choosing fault ride-through method and reference for simulation study.

Study on Characteristics of ±800kV DC Composite Insulators

This paper presents the basic structure parameters of 800 kV DC composite insulator specimen and the pollution test scheme under whole voltage and whole structure dimension. The condition of 800 kV DC composite insulator pollution test under whole 800 kV voltage and whole structure dimension completed in STRI, which is completed first time in the world, is introduced. The study results indicate that the linear relation between the flashover voltage and the length of 800 kV DC composite insulator is high-blooded. The consistency of test data between STRI and CEPRI is good. The flashover characteristics of I string and V string under whole voltage and whole structure dimension is confirmed. The formula of DC pollution flashover grads calculated by SDD of DC composite insulator is obtained.