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Yang H.-F.,CSG EHV Power Transmission Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

The cooperation of AC-DC control and protection functions has important influence on the security and stability of the power system with the characteristics of long-distance, high power and combined operation of AC/DC. HVDC fundamental and second harmonic protections are the basic cooperation function between the AC and DC system. The 50 Hz and 100 Hz protection setting principles of the AC/DC hybrid transmission system are studied through EMTDC and RTDS simulation. The setting method based on the longest clearing time of AC faults and the overload capability of the HVDC main equipment is proposed, and the quantitative method based EMTDC simulation is presented. Source


Chen Y.-Z.,China Southern Power Grid Co. | Wang Q.,China Southern Power Grid Co. | Cai Y.-L.,China Southern Power Grid Co. | Gu B.-Q.,China Southern Power Grid Co. | And 2 more authors.
Gaoya Dianqi/High Voltage Apparatus | Year: 2013

The China Southern Power Grid (CSG) has installed 6 sets of DC deicers on its backbone transmission grid since the ice disaster in 2008, among which the DC deicer in Gaopo substation of Gao-Zhao ±500 kV DC transmission lines is the first OPGW deicer in CSG. Most of the existing DC deicing researches concern the analyses of provincial power grid and transmission lines. However, the icing on overhead ground lines has become the secondary influencing factor in the causation of power system fault in winter. In this paper, the above 6 sets of DC deicers are described with emphasis on the OPGW deicer, and the deicing process and efficiency after the installation of deicing switches are analyzed. The feasibility and necessity of OPGW deicing is discussed, and suggestion of making a DC deicing process and installing deicing switches is offered to improve deicing efficiency. Source


Wu T.,Wuhan University | Ruan J.-J.,Wuhan University | Zhang Y.,CSG EHV Power Transmission Company | Chen C.,Wuhan University | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

A large number of fires bring serious risks to the safety operation of the power lines and power grids due to extreme droughts and high temperature climate in recent years. In order to improve the maintenance and protection technology of transmission lines under wildfires, characteristics of fire induced trips and strategies of protection and control are analyzed by combining the statistical data of 220~500 kV lines trips under wildfires with the behavior of fires. The trips of transmission lines under fire has obvious seasonal and spatial distribution, low success rate of reclosing, high proportion faults near tower and mid-span of lines under wildfires, and high success rate of forced line energization. Fire induced trips may be identified according to the features of pre-discharge current under forest fires and the properties of the fault current and voltage waves. Combined with the temperature-time characteristics of the wildfires and the insulating properties of line gaps, the reclosing of relay and control method against forest fires faults should be adjusted in fires accidents, to reduce outage time and decrease the influence of the reclosing failure on the devices and systems. Source


Li J.,China Southern Power Grid Co. | Wang Q.,China Southern Power Grid Co. | Tang J.,China Southern Power Grid Co. | Zhu J.,China Southern Power Grid Co. | Liu B.,CSG EHV Power Transmission Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2015

A segmented DC ice-melting scheme is proposed to solve the de-icing problem for the long distance overhead ground wire composed of different types of wires. The connection modes of common ground wire and optical fiber composite overhead ground wire in the DC de-icing scheme are analyzed. And a method for computing the ice melting current is presented for the design of the DC de-icing scheme. Consequently, a segmented DC de-icing appraoch is designed for the overhead ground wire of Li-Gui transmission line with consideration of the Guilin substation DC ice-melting device and the overhead ground wire parameters of Li-Gui transmission line. Simulation result via software PSCAD/EMTDC and the actual application demonstrate that the present de-icing approach is feasible and effective. ©, 2015, Xi'an High Voltage Apparatus Research Institute. All right reserved. Source


Lei M.-D.,CSG EHV Power Transmission Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2012

An unsuccessful conversion from metallic return of pole 1 to ground return in debugging phase after reform of Tianshengqiao-Guangzhou HVDC control and protection system is discussed. The waveform record and the line current at the fault moment are analyzed, and the metallic return switch(MRS) is tested by considering the protection configuration and principle of MRS. The result indicates that insulation defect of the arrester on the resonance circuit of MRS causes protective action of MRS in test. Correspondingly, preventive test for insulation of conversion bus equipment is suggested during annual outage for maintenance. Source

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