254 IEEE TRANSACTIONS ON SMART GRID, VOL. 2, NO. 2, JUNE 2011 A Novel Smart High-Voltage Circuit Breaker for Smart Grid Applications Jun Liu, Student Member, IEEE, Garng M. Huang, Senior Member, IEEE, Zhiying Ma, Senior Member, IEEE, and Yingsan Geng, Senior Member, IEEE Abstract—In this paper, we propose a new “intelligent opera- tion” concept for high-voltage SF gas circuit breakers, in which the moving contacts are self-adaptively controlled from one posi- tion to an adjacent position to improve the circuit breaker life cy- cles. To analyze the concept intelligent operation, a new model of high-voltage SF gas circuit breaker is developed, and the moving characteristics of the new type circuit breaker are computed based on the newly designed model. Then both mechanical and electrical wears are quantitatively analyzed according to the breaker’s new moving characteristic. Finally, we demonstrate the life cycle im- provement of the new type of high-voltage SF gas circuit breaker. Our analysis can also be used to estimate the remaining life cycle of a breaker based on the tallied data collected by our intelligent modules. Index Terms—Electrical wear, high-voltage SF gas circuit breaker, intelligent operation, mechanical wear, phase control technology, reliability. I. INTRODUCTION C IRCUIT breakers have been playing a critical electrical apparatus role to control and protect power equipments including power transmission lines for high-voltage power sys- tems during faults. It has become even more essential for smart grid applications even during normal operations: the smart grid needs to break or make rated current more frequently besides the function of fault protection. For examples, optimal transmis- sion switching is able to cut the generation costs greatly based on optimal power flow analysis [1]. It is also shown that branch and bus coupler switching [2] is a powerful control option to find optimum robust network topologies. In addition, [3] shows that network reconfiguration can alleviate or remove the poten- tial overload of a monitored line. In addition to transmission switching, researches on the important role of interruptible loads [4], [5] in deregulated electricity markets to ensure both power system security and optimum electricity prices also have been Manuscript received January 12, 2010; revised June 09, 2010, September 30, 2010, December 08, 2010; accepted January 29, 2011. Date of current ver- sion May 25, 2011. This work was supported in part by the China Scholarship Council and Texas A&M University, College Station. Paper no. TSG-00005- 2010. J. Liu, Z. Ma, and Y, Geng are with State Key Laboratory of Electrical Insula- tion and Power Equipments, Department of Electrical Engineering, Xi’an Jiao- tong University, Xi’an, Shaanxi 710049, China (e-mail: jliu1912@gmail.com; zyma@mail.xjtu.edu.cn; ysgeng@mail.xjtu.edu.cn). G. M. Huang is with Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843-3128 USA (e-mail: ghuang@tamu.edu). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TSG.2011.2134113 demonstrated; hence, circuit breakers will be required to per- form more normal operations (i.e., load shedding) under rated current in the distribution network of future smart grid. To meet the demands for these smart grid applications, it is pertinent to develop new technology to lengthen life cycles (the number of operations) of high-voltage breakers for transmission systems for more reliable operations. Ever since SF gas was discovered in the 1900s, the devel- opment of high-voltage circuit breakers has made considerable progress. Nowadays, SF gas circuit breakers (GCBs) have be- come the mainstream of the high-voltage market, and have been widely used in all applications involving power system volt- ages in the range of 72.5 kV to 800 kV [6]. Although SF has greenhouse effect, it is exclusively used as an insulation and quenching medium for high-voltage circuit breakers because of its high insulation strength and high interruption capability of fault current at present; while alternative medium, such as vacuum, limits its use only to voltages up to 100 kV [7]. Our objective here is to enhance breaker reliability by lengthening its lifetime in such a way that the breaker will need less mainte- nance and serve longer time in power systems. The implication is that less SF need to be produced and used for GCBs, which will induce considerable environmental benefits. Historically, the development of high-voltage SF GCB has experienced three periods, namely, the two-pressure [8] stage, the puffer type stage, and the hybrid type circuit breaker stage. A hybrid type GCB has the mixed structure of self-blast thermal expansion type and puffer type GCB. A novel GCB named intel- ligent circuit breaker is proposed in this paper. Conventionally, circuit breaker is considered unintelligent on its own. Former researches of circuit breakers focused mainly on monitoring the SF gas parameters [9], the control circuit status [10] of GCB, etc. Traditional GCB receives an open-or-close signal from re- lays, and then operates simply according to its factory setting, which cannot be modified or adjusted for different situations. To increase life cycles, we propose to develop intelligent controls on the operating mechanism to improve the basic interrupting characteristic of GCBs to meet the demands of smart grid ap- plications for GCBs’ critical role for frequent rated current op- erations. The proposed intelligent operation of high-voltage gas circuit breakers take advantage of the advancement of digital circuits and flexible hydraulic valve regulators to lengthen the operation life cycles of breakers with relatively low extra cost. Our data and analysis confirm the effectiveness of our approach: the life cycles of both faulted and normal operations can be in- creased substantially since our intelligent control unit will re- duce both electrical and mechanical wears substantially. Our analysis can also be used to predict the remaining lifetime of 1949-3053/$26.00 © 2011 IEEE