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Du N.,Tsinghua University | Guan Y.,Tsinghua University | Zhang J.,Inner Mongolia Electrical Power Group Co. | Niu J.,Inner Mongolia Electrical Power Research Institute | And 2 more authors.
IEEE Transactions on Power Delivery | Year: 2011

In view of frequent and severe overvoltage failures of 40.5-kV vacuum circuit breakers (CBs) while switching off the shunt reactors in the 35-kV distribution systems in China, a series of field tests was carried out to determine the mechanism of this kind of disruption. The transient process and phenomena were analyzed and summarized based on the overvoltage waveforms obtained from the field tests. The experimental results indicated that the probability of reignition is greater for a 40.5-kV CB than in a 12 kV one. The interphase overvoltage was especially critical. The causes of severe overvoltages were analyzed, and it was indicated that the difference of CBs, multireignitions by the interphase coupling, and the different application conditions were the main effect factors. In addition, some suggestions were given. © 2011 IEEE.


Du N.,Tsinghua University | Guan Y.,Tsinghua University | Zhang J.,Inner Mongolia Electrical Power Group Co. | Niu J.,Inner Mongolia Electrical Power Research Institute | And 2 more authors.
Qinghua Daxue Xuebao/Journal of Tsinghua University | Year: 2010

Overvoltage failures frequently occur in China with 40.5 kV vacuum circuit breakers switching off shunt reactors. Field tests were made to analyze the transient process caused by the opening operation and the overvoltage principles for this condition. The results indicate that current chopping does not induce critical overvoltages, but that the frequent high overvoltages are caused by the multiple reignitions and voltage escalation of the first clearing pole, as well as the virtual current chopping with large equivalent chopping currents of the last two clearing poles due to high-frequency interphase coupling. Although multiple reignitions of the last clearing poles greatly decrease the overvoltage amplitude, the load overvoltages, especially the interphase overvoltages, probably may significantly exceed the permitted values.


Du N.,Tsinghua University | Guan Y.-G.,Tsinghua University | Zhang J.-S.,Inner Mongolia Electrical Power Group Co. | Niu J.-R.,Inner Mongolia Electrical Power Research Institute | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2010

In view of frequent overvoltage failures of 40.5 kV vacuum circuit breakers switching off shunt reactors in China, a series of field experiments were carried out, as well as comparison of several common protectors. The results indicate that, it is even more important to suppress overvoltages between phases than those between phase and ground. For conditions of this paper, protections which can effectively suppress both phase-to-ground and interphase overvoltages are: gapless combined MOA, three-gap combined MOA, and R-C protection. And it is much better while R-C protection installed at reactors than that installed at switchgear. The results of this paper have guiding meanings for applications.


Du N.,Tsinghua University | Guan Y.-G.,Tsinghua University | Zhang J.-S.,Inner Mongolia Electrical Power Group Co. | Niu J.-R.,Inner Mongolia Electrical Power Research Institute | And 2 more authors.
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

Aiming at the operating conditions of 40.5 kV vacuum circuit breaker switching off shunt reactors, and in order to eliminate deficiencies in the existing simulation model, a general review of simulating researches on vacuum circuit breakers switching off small reactive current is given. A three-phase model of 40.5 kV circuit breakers switching off shunt reactors is set up based on the experimental results of a type of 4.5 kV vacuum circuit breaker, including the dielectric strength characteristics, high-frequency current quenching criteria and chopping current. And the interphase coupling is considered in the model. A three-phase simulation is conducted for the transient process of the vacuum circuit breaker switching off shunt reactors via ATP-EMTP, and the simulation results coincide almost with experimental results.


Zheng W.-J.,Tianjin University | Zheng W.-J.,Inner Mongolia Electrical Power Group Co. | Wang H.-L.,Tianjin University
2011 IEEE 18th International Conference on Industrial Engineering and Engineering Management, IE and EM 2011 | Year: 2011

Power industry plays an important role in the development of China's energy industry. Organizational performance means that administrators use evaluation index system to evaluate the overall effect of the organization's operating results. Organizational performance management can focus on performance of the organization, a department, and processes to build a product or service. Partial least squares (PLS) regression is a recent technique that generalizes and combines features from principal component analysis and multiple regression. In this paper, we first established a supply enterprise performance evaluation index system. Then using partial least squares regression model, organizational performance of a number of Inner Mongolia Electric Power Corporation power companies were quantitative evaluated. © 2011 IEEE.


Yang S.,North University of China | Han Q.,North University of China | Xu L.,North University of China | Lu S.,Inner Mongolia Electrical Power Group Co.
Dianwang Jishu/Power System Technology | Year: 2011

Firstly, based on seven aspects, namely the image, the expectation, the perception on power quality, the perception on quality of service (QoS), the perceived value, grumble and allegiance, an index system to comprehensively evaluate the satisfaction of electric power customers is established. Then the feasibility of optimizing BP neural network by fish swarm algorithm is analyzed and the procedures for the optimization of BP neural network by fish swarm algorithm are researched. Finally, according to evaluation data of electric power customer satisfaction in five regions in 2009 and based on the assessment of expert scoring, the customer satisfactions are carried out by neural network and fish swarm-optimized algorithm neural network respectively. During the convergence there are 130 times for the former to close to the error figure about 0.1 and only 10 times for the latter to stay at local optima; when error figure is 0.001, after 168 times of training the former reaches the target and only after 88 times of training the latter reaches the target. The results show that the proposed method is effective for the evaluation on electric power customer satisfaction, and the method of fish swarm algorithm-optimized BP neural network is accurate, fast, simple and easy.

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