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Suonan J.,Xi'an Jiaotong University | Zhang J.,Northwest China Power Dispatch and Communication Center | Liu L.,Xi'an Jiaotong University | Tan S.,Xi'an Jiaotong University | Yang Z.,Xinxiang Electrical Power Supply Corporation
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2010

The traditional distance protections applied to the AC-DC power system usually induce transient overreach, especially for the Inverter commutation failure in DC system. It is found that the transient overreach in AC-DC power system is due to fault transient signals containing a large number of low-frequency components of the slow decay and non periodic components and high frequency components. The voltage and current of tuning point based on distributed-parameter model are calculated, and the equations for identifying the distance between tuning point and the point of failure by R-L model are established to put forward a protection scheme. The simulations show the ability for distinguish internal fault from external fault and preventing transient overreach.

Suonan J.-L.,Xi'an Jiaotong University | Yang C.,Xi'an Jiaotong University | Yang Z.-L.,Xinxiang Electrical Power Supply Corporation | Song G.-B.,Xi'an Jiaotong University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

As for long parallel UHV/EHV transmission lines, the sensitivity and reliability of the differential protection is affected a lot by the distributed capacitive current. By establishing the ∏ mode circuit for the parallel transmission lines, a novel time-domain capacitive current compensation method is proposed. This method without requirement for the information of the other line works better than the traditional compensation methods, since it can compensate both the interphase capacitive current and the capacitive current between parallel transmission lines. Theory analysis and EMTP simulation show that, the reliability and sensitivity of the differential protection on parallel transmission lines is effectively enhanced by using the compensation method. In addition, since the proposed algorithm is required for neither high sampling rate nor heavy computation, it can operate well on the existing relay devices with limited sampling rate and telecommunication traffic. © 2010 Chin. Soc. for Elec. Eng.

Li Y.,Huazhong University of Science and Technology | Jing P.,Huazhong University of Science and Technology | Wang L.,Huazhong University of Science and Technology | Xu Y.,Xinxiang Electrical Power Supply Corporation | And 3 more authors.
Dianwang Jishu/Power System Technology | Year: 2012

With the increasing application of PV and wind power, special attention is being paid to energy storage system, which is regarded as an important manner to smooth power fluctuation. Reasonable layout of energy storage systems become an important issue to enhance the ability of power grid to accept the new energy sources. In order to study the impacts of various energy storage systems on electromechanical transient response of power grid, a versatile energy storage system model suitable to the electromechanical transient calculation of power grid is proposed, by which the characteristic parameters of energy storage system such as time-delay of system resoponse, limitation of charging and discharging and restraint of energy storage capacity can be considered, the effectiveness of the proposed model is verified by user-defined modules in Power System Analysis Software Package (PSASP), a study on the impact of sudden change of output of PV power generation on frequency of the example system is simulated, the suggestion on layout of energy storage systems is given.

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