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Wu R.,North China Electrical Power University | Bao Z.,North China Electrical Power University | Wu H.,CSG EHV Power Transmission Company | Fan B.,North China Electrical Power University
2016 3rd International Conference on Systems and Informatics, ICSAI 2016 | Year: 2016

In this paper, we study the service importance evaluation problem in the smart grid. Considering the complexity of power communication services is gradually deepening with the accelerated intelligent process of modern power grid, we propose an evaluation method combining multiple factors fusion aimed at improving the accuracy of evaluation results and reflecting the real status of services in the smart grid. In the proposed method, we first establish a comprehensive evaluation model that contains the complete evaluation indicator system for two factors and introduce the concept of contribution coefficient. Then we propose the evaluation method for single factor and quantify the evaluation indicators of service importance based on communication factor and power grid factor respectively. According to the multifactorial characteristics of services, the fusion process of two-factor service importance is carried out by contribution coefficient finally. Case analysis shows proposed approach can overcome the disadvantage that traditional methods only apply to single factor or fail to effectively combine expert's subjective judgment and the objectivity of evaluation methods, meanwhile guarantee the rationality of evaluation results. © 2016 IEEE.

Ma H.,CSG EHV Power Transmission Company | Huang Z.,CSG EHV Power Transmission Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2014

The failed LW6-220 circuit breakers with falling-off failure of insulation lever are analyzed theoretically, and are compared with normal LW6-220 circuit breaker. Conclusion is drawn that the falling-off failure of insulation lever of the LW6-220 circuit breaker is related to material, manufacturing process, circuit breaker structure, and use time. Moreover, a direct inspection method and a testing method are presented for preventing the LW6-220 circuit breaker from falling-off failure of insulation lever. ©, 2014, Xi'an High Voltage Apparatus Research Institute. All right reserved.

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.

Yang J.,CSG EHV Power Transmission Company | Chang K.,CSG EHV Power Transmission Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2015

Yunnan-Guangdong UHVDC Project is the first ±800 kV UHVDC project in the world. The starting point of the project is the convertor station in Chuxiong, Yunnan Province, and the drop point is Suidong Convertor Station in Guangdong Province. The transmission capacity is bipolar 5 000 MW with ±800 kV rated voltage. This project takes the configuration of double 12-pulse valve groups in series, each pole includes valve group 1 and valve group 2. In this paper, based on the commissioning islanding testing of ±800 kV Chu-Sui ultra-high voltage direct current system and the before-and-after comparisons of the logic optimization of switching in bypass pair by islanding approach through FTP system, the effectiveness of the logic optimization of switching in bypass pair at rectifier side is verified. The analysis reveals that the inhibition of switching in bypass pair at rectifier side by islanding approach avails to the system stability. ©, 2015, Xi'an High Voltage Apparatus Research Institute. All right reserved.

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.

Tian X.-W.,CSG EHV Power Transmission Company | Deng B.-F.,CSG EHV Power Transmission Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

Xing-An HVDC Project occurred several times system outages caused by the filter blocking on the valve cooling system fault since December 2008. To find out the reasons leading to block, the configuration of the valve cooling system Xing-An HVDC Project was introduced and the reasons leading to scale in the valve cooling system were analyzed the Principle causes. Also recommendations for improvement based on engineering design deficiencies were made. Final settlement of the reasons was put. In order to achieve the main filter to prevent blockage caused HVDC system outage purpose, targeted preventive actions were put forward well which can improve the reliability, security and stability of the system.

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.

Guo S.-Y.,CSG EHV Power Transmission Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2013

This paper introduced an explosion accident of 500 kV SF6 circuit breaker in Xingren converter station, the structure of breaking unit, theory of interruption and action process about the SF6 circuit breaker was discussed, combining with the practical situation, all possible factors of the accident is analysised. Finally the reasons of the accident were presented: the shafts in the T-mechanism were displaced caused by the two missing bearings after many opening and closing, a pin had sheared off by the excessive forces and finally breaked off from the mechanism; the arcing contacts could not contact after closing operation, a stable short arc was initiated across the arcing contacts, the pressure inside the breaking unit increased for the heated gas. At last, the interrupter exploded and led to a grid short circuit accident. To avoid similar accidents, this paper provided the corresponding proposal about quality control of manufacturers.

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.

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.

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