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Xi'an, China

Ma Z.,Xian Xd Power Systems
2011 1st International Conference on Electric Power Equipment - Switching Technology, ICEPE2011 - Proceedings | Year: 2011

The electronic control circuit of each thyristor control unit (TCU) in thyristor valves for Three Gorges-Shanghai HVDC Power Transmission Project can not only control and detect the thyristor level, but also has the function of both normal protective firing (PF) and recovery protective firing (RP). Some problems on circuit design of recovery protective firing are discussed here. © 2011 IEEE. Source


Zhang H.,Xian Jiaotong University | Yang X.-P.,Xian Xd Power Systems | Ma X.-K.,Xian Jiaotong University | He B.,Xian Jiaotong University
Nonlinear Analysis: Real World Applications | Year: 2012

This paper deals with limit cycle behaviors in DCDC boost converters with a proportional-integral (PI) voltage compensator, which is a popular design solution for increasing output voltage in power electronics. Extensive cycle-by-cycle numerical simulations are used to capture all limit cycle behaviors. It is found that there exist two types of limit cycle behaviors rather than only one type in a boost converter. For each type of limit cycle, its underlying mechanism is revealed by circuit analysis. Moreover, the critical condition is derived to predict the occurrence of the limit cycle behaviors in terms of Routh stability criterion, and the analytical expressions for the limit cycles I and II are given based on the averaged model approach. Finally, these theoretical results are verified by numerical simulations and circuit experiments. © 2012 Elsevier Ltd. All rights reserved. Source


Wang H.-Y.,Xian Xd Power Systems
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

In Xibei-Huazhong LingBao BtB expansion project, the corresponding rated DC current is the largest in the world at present, the thyristor trip caused by overhigh junction temperature occurred frequently, during system commissioning test. These events have been investigated in this paper, and the real trip reason is not from thyristor valve cooling system, but from the design unreasonable of thyristor junction temperature protection criterion in AREVA's valve based electronic equipment (VBE). The improvement suggestion is cancel the repeated temperature protection from VBE, or adjust the temperature protection criterion and only makes the backstage record to its application. Source


Zhang J.-F.,Xian Xd Power Systems
Gaoya Dianqi/High Voltage Apparatus | Year: 2013

Light triggered thyristor valves have been widely used in many Chinese HVDC or UHVDC power transmission projects, such as Xiluodu Project, GG I Project, and GG II Project, where many thyristors are connected in series in a thyristor valve. Break over diode (BOD) circuits are integrated into each thyristor to ensure reliable stand-by emergent protective triggering. The author analyzes the working principle of BOD circuit, and discusses the limiting principle of the maximum number of thyristors triggered by the BOD circuits in a thyristor valve. Source


Zhang H.,Xian Jiaotong University | Yang X.-P.,Xian Xd Power Systems | Ma X.-K.,Xian Jiaotong University | Zheng F.,Xidian University
Mathematics and Computers in Simulation | Year: 2011

This paper deals with two types of bidirectional Hopf bifurcation phenomena in two-stage cascade DC-DC buck converter, which is a popular design solution for obtaining larger conversion rates in distributed power systems (DPS). By means of "exact" cycle-by-cycle numerical simulations, it is found that two types of bidirectional Hopf bifurcations that never occur in standalone buck converter are observed under the variations of some particular circuit parameters. Based on the derived averaged model, theoretical analysis is performed to identify the two types of bidirectional bifurcations by judging in what way the eigenvalue loci of the Jacobian move, and further to reveal their underlying mechanisms. In addition, some behavior boundaries are given in parameter space, and some rules are proposed to avoid the occurrence of the bidirectional Hopf bifurcations. Finally, experimental results are presented for verification purposes. © 2011 Published by Elsevier B.V. on behalf of IMACS. Source

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