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Zhao H.,North China Electrical Power University | Xia Y.,Xian power Supply Company | Xue N.,North China Electrical Power University
Advanced Materials Research | Year: 2013

The substation is one of the most important nodes for the power system voltage control. Its dynamic behavior is usually characterized by the interaction of dynamic load models, describing continues variables governed by differential equations, and of discrete controllers and coordinated logic, describing symbolic variables governed by discrete behaviors, logic rules and switching mechanisms. Therefore, the operation and control of the substation is a typical hybrid dynamic system. To make an effective voltage coordinated control in substation, this paper proposed a hybrid predictive control strategy. First, the discrete-time hybrid automata model was given for describing the hybrid voltage control system in substation. Then, by using the voltage-security control constrain instead of the goal of voltage-security control, the voltage coordinated control problem can be converted to a minimization cost problem on the premise of the voltage-security control, based on the technology of the MPC. And, for the discrete control characteristics and different control delays of multi-controllers, a branch and search algorithm was designed to solve the hybrid predictive control problem. This proposed algorithm is suitable for the voltage predictive control of substation, which have less control variables and different controllers' delays. Finally, the coordinated controller was designed on Dymola. And the example of BPA test system three generations and ten buses included was given for simulation analysis and the verification by the proposed approach for substation coordinated voltage control. The results of simulation showed that the proposed control strategy in the paper is feasible. © (2013) Trans Tech Publications, Switzerland. Source


Ren X.-X.,Xian power Supply Company | Luo S.-B.,Henan University of Science and Technology | Ma S.-F.,China Coal Pingshuo Coal Co. | Yun B.-J.,Xian Xirui Protection and Control Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

Because practical transmission systems and fault situations are rather complex, non-unit transient based protection of transmission line is difficult to reliably protect the whole line. On the basis of illustrating the principle of non-unit transient based protection, according to the characteristic that the transmitting modes of the traveling waves generated by the same fault type in transmission line are similar, the method to improve internal-fault right discriminating rate of non-unit transient based protection is presented, which is that making sure forward external faults are reliable non-operation and set respectively in terms of fault types. And the ATP simulation tests of 500 kV EHV transmission system are conducted. The results show that the new method is able to improve the internal-fault right discriminating rate of non-unit transient based protection effectively. Source


Liu J.,Shanxi Electric Power Research Institute | Duan J.-L.,Xian power Supply Company | Duan J.-L.,Xian University of Science and Technology
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

To identify the key elements to line losses, make the loss reduction planning and establish the goal of loss reduction scientifically, a family of loss limitation indexes is established including loss limitation, conductor size loss limitation rate and loss reduction rate, VAR loss limitation rate and loss reduction rate, transformer improvement loss limitation rate and loss reduction rate, load balancing loss limitation rate and loss reduction rate, optimal operation loss limitation rate and loss reduction rate and total loss limitation rate and loss reduction rate. A loss reduction optimal planning method is put forward, which is based on the proposed loss limitation indexes and loss reduction indexes. Some examples are given showing that the suggested indexes can identify the extent of the influence of an individual element on line losses and the potential of loss reduction. It is also shown that the proposed planning method can obtain the satisfied loss reduction scheme. Source


Liu J.,Shanxi Electric Power Research Institute | Yun B.,Xian Xiri Electrical Power Automation Co. | Cui Q.,Xian power Supply Company | He L.,Xian power Supply Company | Zheng J.,Xian power Supply Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

In order to quickly clear off the fault and avoid over-tripping, a GOOSE based distributed intelligent feeder automation system is put forward. A partitioning model is established for distribution networks. The structure of the feeder automation system proposed is described. The fault allocation principle, the automatic fault isolation process and the automatic restoration process of the open-loop distribution system and closed-loop distribution system are detailed, respectively. An open-loop distribution system, a closed-loop distribution system and a cascade switch station group are used as examples to demonstrate the approach. It is shown that with the proposed methodology, the isolation and restoration can be implemented at one go without any over-tripping to meet the requirements of customers asking for particularly high reliability. ©2010 State Grid Electric Power Research Institute Press. Source


Liu J.,Shaanxi Electrical Power Research Institute | Zhao S.,Shaanxi Electrical Power Research Institute | Yun B.,Xian Xiri Electrical Power Automation Co. | Cui Q.,Xian power Supply Company | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

In order to solve fast power supply restoration after temporary fault and further improve the reliability of the distributed intelligent based feeder automation system with fast self-healing performance, a novel re-closing control strategy is put forward. The re-closing process of a switch is started only when the switch is energized. Once the re-closing is succeed, a message is sent to adjacent switches so that makes them closed. With the proposed re-closing strategy, not only the temporary faults and permanent faults can be effectively indentified, but also the restoration process can work normally even with fault in communication channel. An approach to deal with the refused tripping of switches is proposed and bad influence of the refused tripping on the restoration process is remarkably reduced. Based on the analysis, it is pointed out that when there is a missed detection or a mistaken detection of fault current due to accidental interference, the fault influence can only temporary enlarged and then it will be finally well isolated in minimum area. It is suggested that super capacitor is used as the energy storage device for back-up power supplies in the intelligent electronic devices (IEDs) so as to enhance reliability. The results of many cases study given in the paper show the feasibility and effectiveness of the proposed approaches. © 2011 State Grid Electric Power Research Institute Press. Source

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