Zhengzhou Power Supply Company
Zhengzhou Power Supply Company
Li X.,Shanghai University of Electric Power |
Liu Y.,Zhengzhou Power Supply Company |
Zhu W.,Shanghai University of Electric Power
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2017
In order to classify the kinds and fault sequence of composite voltage sag sources in distribution network with harmonic, a new method to classify these composite voltage sag sources is proposed. Firstly, according to different voltage sag waveforms triggered by different types of voltage sag sources, the composite voltage sag sources containing single-phase grounding fault are classified from the composite voltage sag source consisted of transformers and induction motor. Then the intersection unbalanced degree and second-harmonic are employed to classify the composite voltage sag sources containing single-phase grounding fault. Additionally the fault sequence is classified through Mahalanobis distance and probability neural network, and a complete classification and identification method is formed. Finally, the proposed method is verified through simulation experiment, the results show that this method can well classify the kinds and fault sequence of composite voltage sag sources, and recognition accuracy is higher than 96%. In addition, the proposed method is compared with the method of the combination of EMD energy entropy and PNN, the comparison result shows that the accuracy of the proposed method is superior to the latter's. © 2017, Power System Protection and Control Press. All right reserved.
Zhang Y.-H.,Zhengzhou Power Supply Company |
Zheng D.-L.,XJ Electrical Company |
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.
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.
Zhai J.,Zhengzhou Power Supply Company |
Chen X.,Zhengzhou Power Supply Company
Lecture Notes in Electrical Engineering | Year: 2014
It is difficult for conventional relaying algorithms to detect incipient faults, such as insulator current leakage, electrical faults due to tree limbs, and transient or intermittent earth faults, which are frequent in distribution networks. With the time, they may lead to a catastrophic failure. In order to avoid this situation, S-transform technique is proposed to extract the suitable features of incipient fault in this chapter. A least square support vector machine (LS-SVM) classifier is developed utilizing the features so that incipient fault is distinguished from the normal disturbances. Then the polarity of magnitude difference of residual current is used to determine the fault section of distribution network. The proposed technique has been investigated by ATP/EMTP simulation software. Simulation results show that this technique is effective and robust. © 2014 Springer International Publishing Switzerland.
Yan L.-M.,Zheng Zhou Power Supply Company
19th International Conference on Industrial Engineering and Engineering Management: Engineering Economics Management | Year: 2013
Market reformation is an inevitable trend, the diversification and complexity of risks faced by power generation enterprises in our country is increased. This thesis describes the risk management for power generation enterprises in detail according to the risk-management processes on the basis of introduction to the theoretical framework of risk management. At the section of risk identification, this thesis discusses the external and internal risks of power generation enterprise, and analyzes the impact of current domestic and foreign energy situation to power generation enterprises. This thesis focuses on risk assessment and discusses the risk assessment model. Combining economic evaluation and characteristics of Chinese electricity market, this thesis applies VaR method in the risk assessment of power industry and creatively brings up a risk assessment model. This model is applicable not only to the power industry research but also to the specific risk assessment model for power generation enterprises. © Springer-Verlag Berlin Heidelberg 2013.
Yang Q.,Chongqing University |
Sima W.-X.,Chongqing University |
Sun Y.-H.,Zhengzhou Power Supply Corporation |
Yuan T.,Chongqing University |
Sun C.-X.,Chongqing University
Gaodianya Jishu/High Voltage Engineering | Year: 2012
Mixed-voltage multi-circuit transmission line on the same tower can be considered in UHV grid in eastern China where the area for the line corridor is limited. It is of great significance to study the back flashover performance of the UHV mixed-voltage multi-circuit transmission lines on the same tower (UMMTL). Consequently, taking the influence of the working voltage into account by using statistical method, basing on PSCAD/EMTDC, we established a simulation model of the back-flashover performance for quadruple-circuit transmission line with dual voltage 1000 kV/500 kV on the same tower. Compared with the conventional lines, characteristics of the back-flashover performance were summarized for UMMTL. With the consideration for the specific characteristics, the influences of the insulation level of the lateral conductor, one side conductor of the 500 kV upper layer cross-arm and the phase arrangement for 500 kV lines on the back-flashover performance were analyzed. The results show that the back-flashover trip-out rate of the single circuit and the double-circuit for 500 kV lines both decrease when the insulation level of the lateral conductor is enhanced. The back-flashover trip-out rate of the double-circuit for 500 kV lines decreases when the insulation level of the one side conductor of cross-arm is improved. The back-flashover trip-out rate of the single circuit for 500 kV lines is comparatively higher than that of the double-circuit when different phase conductors are used for lateral conductor. Thus the back-flashover performance for 500 kV lines can be improved by enhancing the insulation level of the lateral conductor. The back-flashover performance for 500 kV double-circuit lines can be improved by enhancing the insulation level of one side conductor for upper layer cross-arm, and with the implement of unbalanced insulation as well as different phase conductors for the lateral conductor of 500 kV lines.
Yang L.,Zhengzhou University |
Zeng X.,Zhengzhou University |
Fang Q.,Zhengzhou Power Supply Company |
Lou B.,Zhengzhou Power Supply Company |
And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013
Based on the complex network theory and survivability analysis method, a medium voltage distribution network topology is investigated. The definition of survivability metric and assumptions about survivability topology modeling for a medium voltage distribution network topology are presented. Then, the survivability optimization model is developed. To provide a secondary basis for decision making for the selection of planning program for the medium voltage distribution network, the survivability indicators for different network structures are quantificationally calculated based on the gradually decreasing method. The rationality of this method is verified, and a new way for the safety and reliability analysis of medium voltage distribution network is put forward in the perspective of topological analysis. © 2013 State Grid Electric Power Research Institute Press.
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.