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Liu Y.,North China Electrical Power University | Tian R.,North China Electrical Power University | Zhang D.,North China Electrical Power University | Zhang X.,North China Electrical Power University | Zhou J.,Zhengzhou Power Supply Company
Dianwang Jishu/Power System Technology | Year: 2013

Wind power output characteristics study acts as the basic premise for analyzing its effects on the power system, as well as figuring out or corresponding solutions. Based on the analysis of wind power output fluctuations, this paper summarized the wind power variation discipline from a single wind farm to wind farm clusters, focusing on the space-scale effect of wind farm clusters, that is, the smoothing effect. Firstly, the definition, performance and mechanism of smoothing effect were discussed, and the method of quantitative analysis for influencing factors of smooth effect was proposed. Then, by taking wind farm clusters integrated with a practical regional grid as the case study, the indicator of wind farm clusters' smoothing effect was calculated. The result shows that the negative correlation of wind farm outputs is essential reason of smoothing effect. Finally, the application of smooth effecting to active power balance in power system considering different time scales was discussed.

Lu T.,North China Electrical Power University | Feng H.,Zhengzhou Power Supply Company | Cui X.,North China Electrical Power University | Zhao Z.,North China Electrical Power University | Li L.,North China Electrical Power University
IEEE Transactions on Magnetics | Year: 2010

Corona phenomenon generated from high voltage direct current (HVDC) transmission lines can affect the environment nearby. Based on the upstream finite element method, an iterative algorithm is used to analyze the ionized electric field and the ion current density at the ground level with the wind velocity taken into consideration. The algorithm is efficiently convergent. The proposed method is testified by measurement results of a unipolar line in the presence of wind and a bipolar test line. Finally some examples are analyzed to predict the effect of the wind and to determine the transmission corridor of pm800 kV HVDC transmission line. © 2006 IEEE.

Jia H.,North China Electrical Power University | Zhao H.,North China Electrical Power University | Fang Q.,Zhengzhou Power Supply Company | Liu T.,North China Electrical Power University | Qi Y.,North China Electrical Power University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

As the actual distribution network with tree structure has many branches, it is very difficult to find the fault point using the fault location method based on the single-terminal or double-terminal traveling wave. For the type B traveling wave and the tree structure of the distribution network, a fault location method based on multi-terminal traveling wave is put forward. This method carries out fault location by using the time that the first traveling wave head generated during grounding fault takes to reach the ends of the power lines. According to the theory of fault location method based on multi-terminal traveling wave, the theoretical basis is established and the superiority of the location scheme in the distribution network is examined. The various factors in the distribution network scheme are analyzed by ATP simulation software and MATLAB software. The simulation results show that in distribution network phase-to-ground fault location, the location method based on multi-terminal traveling wave only uses the initial transient traveling wave signal within a very short time, while the fault development in the later stage of the grounding fault has no influence on the initial transient traveling signal. So the fault point can be quickly and accurately found by using multi-terminal traveling wave method. © 2012 State Grid Electric Power Research Institute Press.

Zhang Y.-H.,Zhengzhou Power Supply Company | Zheng D.-L.,XJ Electrical Co. | Xiong W.,Wuhan Building Materials Design and Research Institute Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

10 kV overhead line has the character of broad coverage and high trip rate. The traditional feeder always results in long time fault isolation and frequent feeder-outlet switch motion. It can not shorten blackout area, only through reclosing and cutting power supply repeatedly to remove fault. 10 kV feeder automation solutions divide main trunk line into several paragraphs by increasing the numbers of breakers and load switches and dispose FTU. Through compounding, it can reduce outlet breaker trip, isolate faults area automatically, shorten the troubleshooting time and make the non-fault area restore power supply instantly. The solutions can reduce trip times of the feeder-outlet switch significantly, improve success ratio of the reclosing and promote operation level of the net-work overhead line effectively.

Li H.,Chongqing University | Wang H.-S.,Chongqing University | Shi X.-Y.,Zhengzhou Power Supply Company | Yang C.,Chongqing University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

Based on the analysis of dynamic mathematic models of a wind turbine system with a squirrel cage induction generator(SCIG), an equivalent modeling method and parameters optimization model of a wind farm are proposed based on an improved genetic algorithm(IGA) by using the operational data of a SCIG wind farm with the detailed models. Regarding the two cases of a wind farm including SCIGs with identical parameters and SCIGs with different parameters, the dynamic and transient performances characteristics under the wind speed disturbance and the three-phase short circuit fault at the exit of wind farm are simulated and analyzed. The results are also compared with those by using the detailed model and the capacity weighted equivalent model of the SCIG wind farm. The results show that the proposed wind farm equivalent model has the same wind farm operation characteristics with the detailed model, and it has better representation of the dynamic and transient performances of the wind farms compared with the weighted equivalent model.

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