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Bo Z.-Q.,Smart Grid Research Institute of SGCC | Zhang B.-H.,Xian Jiaotong University | Dong X.-Z.,Tsinghua University | He J.-H.,Beijing Jiaotong University | And 3 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

This paper firstly reviews the recent development in power system protection, with special attention paid to the transient based, wide-area and integrated protection, in order to look into future development of smart relaying protection for smart grids. Taking into account the demand and feature of development of smart grids, this paper mainly introduces current research on smart relaying protection in China. The paper further presents a transient based integrated wide area protection scheme, which outlines the advantages of future smart relaying protection. In the proposed protection scheme, the integrated protection relay incorporating a number of transient based protection algorithms running in parallel is installed at each substation in the protected network area and is responsible for the protection of all the power lines associated with the substation. Each relay communicates with neighboring relays at the remote ends of the associated line section to form an area relay network. A centralised wide area protection device with specially designed protection algorithms is responsible for the backup protection of the entire network through advanced communication with each integrated relay at different substation in the area. Protection algorithms within each integrated relay are divided into two types: these relays on the measurement of local information alone and these require remote information. When a fault occurs on the network, the protection algorithms based on local information alone is able to determine whether it is on its protected line section; the algorithms based on remote information will sent the locally derived information to the remote relays and the wide area protection device and receive information from the remote relays, comparison between the remote and local information will determine whether the fault is within its protected zone. The wide area protection device is also able to determine the actual fault location through the comparison of the information from all the integrated relays within the protected network and issues trip command to associated substations to isolate the faulted section. Source

Guo G.,Smart Grid Research Institute of SGCC | Guo G.,China Electric Power Research Institute | Hu X.,China Electric Power Research Institute | Wen J.,Smart Grid Research Institute of SGCC | Wu G.,China Electric Power Research Institute
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

In this paper, the power characteristics of the arm in the Modular Multilevel converter (MMC) was studied, and the mathematical equation of the instantaneous power of the arm and the DC component of the arm current were acquired. By studying the equivalent circuit of the capacitor charge circuit, the mathematical equation of the equivalent charge current and capacitor AC voltage component were acquired. Based on the mathematical equation of the capacitor AC voltage component, the relationship of magnitude of B with modulate ratio and power factor angle were acquired. Furthermore, the mathematical equation of the magnitude of capacitor AC voltage component were worked out and the design approach of the sub-module capacitor were put forward. The simulation results show the accuracy of the mathematical equation of capacitor AC voltage component and the design approach of the sub-module capacitor. © 2014 Chinese Society for Electrical Engineering. Source

Qi F.,Ohio State University | Xu L.,Ohio State University | Zhao B.,Smart Grid Research Institute of SGCC | Zhou Z.,Smart Grid Research Institute of SGCC
2015 IEEE Energy Conversion Congress and Exposition, ECCE 2015 | Year: 2015

With the development of SiC technology, current rating of the latest SiC MOSFET module goes up to 300A and the gate charge becomes higher than 1000nC, which demands a high gating current to drive the power module. To explore the high current and high temperature (HT) potentials of the SiC MOSFET module, a gate driver circuit with high output current and HT capability is developed. In this paper, particular emphasis is placed on the discussion of the output buffer circuits, including the BJT push-pull, CMOS push-pull and the proposed BJT-CMOS hybrid circuits. Commercially available HT components are used in the design and fabrication of the proposed circuit. The design principles of the circuit are investigated by PSpice simulation and room temperature testing first. Then, the HT experimental testing is performed to verify the full capabilities of the design. The HT experimental testing is performed both on a hotplate of 300°C and in a thermal chamber of 175°C. © 2015 IEEE. Source

Guo G.,Smart Grid Research Institute of SGCC | Yao L.,China Electric Power Research Institute | Wen J.,Smart Grid Research Institute of SGCC
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2016

Modular Multilevel Converter (MMC) can be easily applied to higher voltage and large-scale capacity situations. But when the number of sub-modules is large enough, the capacitor voltage balance and gating pulse distribution in the arm become much more complex, leading to the increased complexity of the control system, the reduced reliability, and much harder debugging. In this paper, the Nearest Level Modulation (NLM) algorithm was introduced in detail, and on this basis, the Floor Modify Number Shifting (FMNS) algorithm was proposed. Since different sub-module groups adopt different floor modify numbers, the effect of carriage phase shift can be achieved, and the distortion of the output voltage is very small. Furthermore, the capacitor voltage balance principle of the sub-module group was analyzed, two capacitor voltage balance control methods were proposed based on this principle, and the application conditions were analyzed in detail. Simulation results show that the prospective effect can be achieved through FMNS algorithm and voltage balance control algorithm. © 2016 Chin. Soc. for Elec. Eng. Source

Han Z.,Smart Grid Research Institute of SGCC | Chen G.,University of Southampton | Cao J.,Smart Grid Research Institute of SGCC | He Z.,Smart Grid Research Institute of SGCC | And 3 more authors.
COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering | Year: 2016

Purpose - The pulsed electro-acoustic method is widely applied for space charge measurement in solid dielectrics. The signals, however, can be seriously distorted during transmission, especially in non-planar specimens. The purpose of this paper is to find an efficient algorithm to correctly recover the space charge profile for different types of specimens. Design/methodology/approach - The distortion can be associated with both geometry and material (attenuation and dispersion). Hence the recovery algorithm consists of two parts, respectively. The influences of geometries, causing the divergences of electric force and acoustic waveform, can be corrected by sets of factors. The attenuation and dispersion of the material can be suppressed based on the transfer function matrix in frequency domain, which could be obtained from calibration. Findings - A general algorithm applicable to three kinds of specimens (single-layer, multi-layer and coaxial-geometry dielectrics) has been proposed. Compared with the other two algorithms in literature, the present one offers the most accurate solution while taking relatively shorter time. In addition, this algorithm is applied on signals measured from a planar low-density polyethylene sample and the results show that the new algorithm is fairly effective with excellent stability in a real system. Originality/value - As one of the most accurate algorithms, the present one is theoretically one-third quicker than the others. This algorithm would be helpful in applications calling for large calculations, i.e. 3D imaging of space charge distribution in XLPE cable. © 2016 Emerald Group Publishing Limited. Source

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