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Liu Y.,University of Jinan | Gao H.,Shandong University | Li N.,Shandong Electrical Power Dispatch Center | Wang C.,University of Jinan | Yan H.,Shandong Disheng Electronics Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control

To realize the substation-area backup protective relay which adopts current differential principle in smart substation, it is necessary to obtain the sampled values (SV) and generic object oriented substation event (GOOSE) from adjacent substations. Therefore the communication schemes between smart substations are researched. There are three schemes suitable for SV transmission with high bandwidth and real-time characteristic, as follows: the solution by means of optical differential protection device, the solution by dedicated data forwarding device and the solution of extending process layer network by wide-area Ethernet. After a comparative analysis, the third solution with good interoperability and high bandwidth is the most suitable scheme for practical application of substation-area backup protection. The paper makes a preliminary theoretical analysis from several aspects, such as SV synchronization method, data channel bandwidth, communication distance, communication reliability and transmission delay. So it draws a conclusion that transmitting SV transparently between smart substations by the third solution is feasible. In the end, a few possible issues need further study is dedicated. ©, 2015, Power System Protection and Control Press. All right reserved. Source

Zhang Y.,Shandong University | Zhang W.,Shandong University | Wang L.,Shandong Electrical Power Dispatch Center
Dianli Zidonghua Shebei/Electric Power Automation Equipment

Based on the model predictive control, a method of coordinated voltage control with CDSRS (Candidate Decision Set Rolling Selection) is proposed. By obtaining the response characteristic of optimal objective node voltage to control variable in the prediction period, the task to solve the coordinated voltage control model is converted into that to carry out the mixed-integer linear programming. According to the locality of voltage control and with the predicted voltage amplitude and response information obtained during the model prediction as the clustering feature indexes, the fuzzy clustering method is applied to determine the optimal objective node after fault, based on which, the CDSRS is carried out according to the significance degree of voltage response. Simulative results show that, under the premise of global coordinated control performance, the scale of candidate decision sets is significantly decreased and the time of optimization calculation is obviously reduced, effectively avoiding the problem of decision set explosion in coordinated voltage control. Source

Huang H.,Zhejiang University | Xu Z.,Zhejiang University | Wu C.,Shandong Electrical Power Dispatch Center | Hua W.,Zhejiang University
Dianwang Jishu/Power System Technology

In power systems, eigenvalue sensitivities are widely applied in both small signal stability analysis and controller design. Based on the perturbation theory of eigenvalue, it has been pointed out that the traditional first-order/second-order eigenvalue sensitivity formula and their associated perturbation expressions would be invalid under resonant modes and near-resonant modes. In allusion to this problem, a fast eigenvalues recalculation algorithm related to system parameter variation is proposed. Using the proposed algorithm, the variation of the eigenvalues for the resonant modes and the near-resonant modes can be effectively estimated, when the power system parameters are varied. The effectiveness of the proposed algorithm is verified by simulation results of IEEE-9 bus power system and IEEE 39-bus power system. Source

Ma J.,Shandong Electrical Power Dispatch Center | Li L.,Shandong Electrical Power Dispatch Center | Huang D.-B.,Shandong Electrical Power Dispatch Center | Tang Y.,Shandong Electrical Power Dispatch Center | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control

In order to meet the demand of the large scale construction in smart substation, on the basis of the analyzing present situation and shortages of the secondary system in smart substation, some key technologies such as ICD detection technology, design technology of the secondary system and SCD difference comparison technology are solved and a practical scheme of building the whole process management platform of the secondary system in smart substation is proposed. Through making good use of technology and management measures, the duty of relevant department and the contents and depth of each link under the new form of technology become distinct. Furthermore, the key points and the whole process of the project are effectively managed. The feasibility and practicability of proposed scheme have been verified with the project of 220 kV Nanjing Road smart substation in Qingdao. Source

Ma J.,Shandong Electrical Power Dispatch Center | Huang D.,Shandong Electrical Power Dispatch Center | Tang Y.,Shandong Electrical Power Dispatch Center | Wu C.,Shandong University | And 2 more authors.
IET Conference Publications

Based on the basic voltage and flux equations of the Doubly Fed Induction Generator, this paper derived expressions of short-circuit current of wind turbines-which are expressed by transient equations of stator and rotor flux. The transient equations of stator and rotor flux were functions of initial values of stator and rotor flux and transient time constants of stator and rotor windings. The initial value of stator flux was calculated, considering the influence of stator resistance, and the rotor flux equation under steady state condition was used to calculate the initial value of rotor flux. Transient behaviors of the stator and rotor flux were analyzed when three-phase faults occurred at terminals of generators, then the transient equations of stator and rotor flux and detailed equations of the short-circuit current of DFIG could be obtained. DIgSILENT/PowerFactory program was used to execute electromagnetic transient simulations when three-phase faults occurred at terminals of generators and at the power system respectively. Simulation results show that it is efficiently to use the equations of short-circuit current proposed by this paper to calculate the short-circuit current of DFIG. As the stator and rotor resistances are considered in the equations of the short-circuit current, calculation results are closer to simulation results, and all differences are less than 4%. Source

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