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Zhao C.,North China Electrical Power University | Li C.,North China Electrical Power University | Li L.,Shanghai Shinan Power Supply Company | Liu Y.,North China Electrical Power University | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2015

To reduce the commutation failure probability of line-commutated-converter based high voltage direct current (LCC-HVDC), we proposed a new forced commutation bridge topology, of which each arm consists of two series of valve groups and one auxiliary capacitor. Based on the new topology, three operation states and switching modes are presented. Then, a control strategy of capacity voltage is proposed and optimal initial charging voltage of capacity is calculated theoretically. Finally, the proposed commutation bridge circuit is developed in PSCAD/EMTDC, and the steady state and transient performances of it is analyzed. Simulation results show that the new topology can mitigate the commutation failure effectively under AC faults condition. Hence, the proposed topology can improve HVDC systems in both commutation failure immunity and recovery performances. ©, 2015, Science Press. All right reserved. Source

Huang W.,Shanghai JiaoTong University | Tai N.,Shanghai JiaoTong University | Tang Y.,Shanghai Shinan Power Supply Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

Microgrid protection can be divided into interconnection protection (IP) and inner microgrid protection (IMP) according to its function. The structure and characteristics of IP are highlighted. The IP is classified into three types: system IP, distributed IP and unit IP according to the classification of microgrid. Through an analysis of microgrid load, operation modes and functions, the configuration strategies of IP are proposed. By considering the complicated structure of large-scale microgrid and co-existence of three types of microgrid, coordinating strategies are also put forward. The typical topology of IEEE P1547.4 is established in PSCAD/EMTDC in order to verify the feasibility and effectiveness of the protection scheme. © 2013 State Grid Electric Power Research Institute Press. Source

Guo C.-X.,Zhejiang University | Zhang L.,Zhejiang University | Zhang J.-J.,Zhejiang University | Zhang J.-J.,Zhejiang University of Science and Technology | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

According to the natural complementarity of wind and solar energy in time and geography, the influences of wind-PV complementary on the system adequacy are calculated in typical summer and winter days while the forced outage of conventional generating units is also considered. The influences are presented in two aspects: seasonal and diurnal. A new energy effective load carrying capacity (N-ELCC) is defined to describe the load carrying capacity of the generating system containing new energy. Variability of N-ELCC from the changes of the wind-PV capacity ratio is analyzed, as well as the effects of N-ELCC on the static reserve capacity. Results show that system adequacy and reliability vary with the wind-PV capacity ratio, the alternation of day and night as well as seasons. Finally, a new energy power generation proposal is proposed scientifically considering the regional climate and environment of the case. The proposal can reduce the reserve investment and improve the economy on the premise of the assurance of reliability. Source

Huang B.,Shanghai JiaoTong University | Huang W.,Shanghai JiaoTong University | Nengling T.,Shanghai JiaoTong University | Lan S.,Shanghai Shinan Power Supply Company | Zong M.,Shanghai Shinan Power Supply Company
Journal of Renewable and Sustainable Energy | Year: 2015

The technologies and application of distributed generators (DGs) are progressing rapidly due to the advantages of DGs. The penetration of renewable resources becomes higher and higher, which brings a lot of problems in distribution networks (DNs). The selection of interconnection point for DGs is required to be solved urgently. In this paper, the factors impacting on the interconnection includes host DN structure, DG characteristics, and DG function, which are analysed in order to provide the constraints for the selection strategy. The objective of the selection strategy is to search the interconnection point with the minimum equipment and operation costs. The IEEE 34-node test bed and a practical project of the building integrated photovoltaic in Shanghai are utilized to demonstrate the effectiveness of the selection strategy. © 2015 AIP Publishing LLC. Source

Shang J.,Shanghai JiaoTong University | Tai N.-L.,Shanghai JiaoTong University | Liu Q.,Shanghai JiaoTong University | Lan S.-L.,Shanghai Shinan Power Supply Company | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

The access of distributed generations adds new sources to distribution network, which changes the grid structure and greatly affects the original protection. This paper analyzes the change of power flow direction, and the influence on short-circuit current and re-closing, which are caused by distributed sources. It also analyzes some solutions, such as reducing the impact of DG on distribution network, using protection of other principles, using multi-point information to determine with the help of communication network. The cooperative protection system with multi-agent is proposed. The paper also details the system structure, key points and the rules followed to evaluate the system performance. Solutions are proposed particularly for the protection of distribution network with DG. Traditional protection and the multi-point information protection based on communication are combined together, which not only overcomes defects of the incomplete of local information, but also guarantees the reliability of protection. Source

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