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12th IET International Conference on AC and DC Power Transmission, ACDC 2016

作者： Hu, Yaping Lu, Jun Zhou, Huafeng CSG Power Dispatching and Control Center Guangzhou510623 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781785612268

This paper presents the mechanism of LCC-HVDC system's commutation failures arising from ac faults. The theoretical analysis of commutation failure is developed by considering direct current dynamics. On the basis of the theoretical analysis, the impacts of ac fault level and fault occurring time on commutation failure are quantified. Moreover, this paper provides a more precise commutation failure criterion. Compared with the conventional, the proposed criterion reveals the relationship between commutation failure and fault occurring time and proves that commutation failure is not probabilistic events. Eventually, the analytical results are verified by the time-domain simulation based on the CIGRE BENCHMARK model in PSCAD/EMTDC.

关键词： Time domain analysis

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The study on CT saturation caused by the circulating current in the delta-winding of converter transformer and its impact on the protection in HVDC system 12

The study on CT saturation caused by the circulating current...

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12th IET International Conference on AC and DC Power Transmission, ACDC 2016

作者： Zhang, Kanjun Qi, Xuanwei Yin, Xianggen Chen, Kun Hu, Wei Zhang, Shiyun State Grid Hubei Electric Power Research Institute Wuhan430077 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9781785612268

In the typical HVDC power system, the current transformers (CTs) between the Y-delta converter transformer and the converter bridge is located in the delta-winding of the transformer. Under such condition, the measuring current of these CTs includes the zero-sequence circulating current of the deltawinding. In the case of the adjacent transformer energization or the fault of AC system, the zero-sequence circulating current in the delta-winding maybe very large containing a great amount of dc component. Thus the CTs will be saturated, resulting in the misoperation of the relevant protection in HVDC system, such as the bridge current differential protection. This sort of misoperation seriously threatens the safe and sound operation of the HVDC power system. In this paper, the misoperation cause is analysed in detail via the PSCAD/EMTDC-based simulation. Based on this, a method is proposed to prevent this sort of misoperation by utilizing the zero-sequence circulating current as the restraint quantity.

关键词： Electric instrument transformers

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The study on sympathetic inrush current of converter transformers in HVDC system and its identification method 12

The study on sympathetic inrush current of converter transfo...

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12th IET International Conference on AC and DC Power Transmission, ACDC 2016

作者： Zhang, Kanjun Qi, Xuanwei Zhang, Shiyun Cao, Wenbin Yang, Fan Yin, Xianggen State Grid Hubei Electric Power Research Institute Wuhan430077 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China

ISBN: (纸本)9781785612268

This paper analyses the mechanism of the sympathetic inrush current of the converter transformer of the HVDC transmission system. The impacting factors of the sympathetic inrush current, including the system impedance, the closing angle and the initial remnant flux of the incoming transformer, and the operating condition of the HVDC system and so on, are analysed utilizing on the PSCAD/EMTDC soft. Based on this, this paper proposed two identification methods for the sympathetic inrush current and the simulation proofs the validity of these methods.

关键词： HVDC power transmission

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An improved optimal control strategy for hybrid AC/DC power system

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IOP Conference Series: Earth and Environmental Science 2018年第1期188卷

作者： C H Gao W M Liu T T Zheng Z W Liu S H Miao Y L Kang Z H Fan Y L Liu M M Zhang State Grid East Inner Mongolia Electric Power Company Limited Electric Power Research Institute Hohhot 010020 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security and High Efficiency Key Laboratory School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

The additional modulation function of high voltage direct current (HVDC) links can improve the system stability while the unavoidable random external disturbance and sudden changes seriously affect the controller performance and the system stability. In this paper, an improved control scheme based on inverse optimal adaptive control is proposed for the hybrid AC/DC system which considers the system parameter error, external disturbance and other random perturbation. The proposed control scheme combines the inverse optimal control approach and the adaptive control method to account for the modelling errors and uncertainty, which aims at the disturbance attenuation and the optimal operating of the hybrid AC/DC power system. Besides, the improved PI (Proportional-Integral) controller based on the lead-lag link for the current control of HVDC system is proposed to further improve system dynamic performance. Simulations conducted on a typical hybrid AC/DC system show the correctness and validity of the proposed control method.

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Coordinated control strategy of doubly fed wind power generation system under unbalanced grid voltage

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IOP Conference Series: Earth and Environmental Science 2018年第1期188卷

作者： C H Gao Y L Kang S H Miao Z W Liu Z H Fan Y L Liu W M Liu T T Zheng M M Zhang State Grid East Inner Mongolia Electric Power Company Limited Electric Power Research Institute Hohhot 010020 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security and High Efficiency Key Laboratory School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

A coordinated control method for doubly fed wind power generation system under unbalanced grid voltage is presented in this paper, which can remove the negative effects of unbalanced voltage on the doubly fed induction generator (DFIG) such as the unbalance of stator and rotor current. And the method can suppress the double frequency oscillations of the output active and reactive power. To improve the operating performance, the operation mechanism of DFIG system with a series grid side converter (SGSC) under unbalanced grid voltage is described firstly, and the strategy for series grid side converter aiming at maintaining the stator three phase voltage balance is proposed, and then the stator and rotor currents will keep balanced. Meanwhile, the mathematical model of the parallel grid side converter (PGSC) is analysed under unbalanced grid voltage and the double frequency power control equation is established. According to the control equation, a control strategy based on a proportional resonance (PR) power compensator for the parallel grid side converter is put forward, then the control goal of suppressing the double frequency oscillations of the output active and reactive power of the whole system simultaneously is accomplished, which improves the output quality of the system and ensures the safe operation of the connected grid. The proposed coordinated control strategy in this paper verified by the simulations of a doubly fed wind power generation system model built in PSCAD/EMTDC.

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Equivalent electromagnetic model of self-blocking MMC with DC fault isolation capability

Equivalent electromagnetic model of self-blocking MMC with D...

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2016 IEEE Power and Energy Society General Meeting, PESGM 2016

作者： Xiang, Wang Lin, Weixing Wen, Jinyu Yao, Liangzhong Zhibing, Wang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Renewable Energy Department China Electric Power Research Institute Beijing China

ISBN: (纸本)9781509041688

Self-blocking MMC (SB MMC) is able to isolate DC fault current and is promising for use in overhead HVDC transmission. Each converter arm of a SB MMC is consisted of half the self-blocking sub-module (SBSM) and half the half bridge (HB) sub-module. This hybrid design achieves the DC fault isolation capability without significantly increase of the cost and power loss. The detailed electro-magnetic simulation of SB MMC with hundreds of voltage levels is time consuming. Since a SBSM can be negatively inserted, the dynamics of SB MMC are different from HB MMC under DC fault condition. The conventional equivalent models of HB MMC are not sufficient for SB MMC. To solve the above challenges, an equivalent electromagnetic model for SB MMC is proposed and verified in this paper. © 2016 IEEE.

关键词： HVDC power transmission

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Optimal protection coordination based on dual directional over-current relays for ring network distribution power systems 8th

Optimal protection coordination based on dual directional ov...

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8th Asia-Pacific Power and Energy engineering Conference, APPEEC 2016

作者： Wang, X.Y. Wang, X.G. Chen, D.H. Su, S. Lin, X.N. China Electric Power Research Institute Haidian District Beijing China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology WuhanHubei Province China

ISBN: (纸本)9781138028463

In terms of Distributed Generation (DG), it is momentous to ensure a fast and reliable protection system for the looped network to avoid involuntary DG disconnection during fault conditions. In this paper, dual setting directional over-current relays are put forward to protect meshed distribution systems with DG. Compared to the conventional approach, which is using a directional relay of onesetting, the new protection coordination scheme counts on the dual setting relays. Dual setting relays are equipped with two inverse time-current characteristics whose settings will depend on the fault direction. The protection coordination problem for the dual setting directional relay is elaborated as a nonlinear programming problem where the objective is to minimize the overall time of operation of relays during primary and backup operation. The proposed scheme is applied to the power distribution network, which is equipped with synchronous and inverter-based DG. The results show that the new protection coordination scheme with the dual setting relay can considerably reduce the overall relay operating time, making it an attractive option for distribution systems with DG. © 2016 Taylor & Francis Group, London.

关键词： Inverse problems

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Numerical study on propagation mechanism and bio-medicine applications of plasma jet

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High Voltage 2016年第2期1卷 62-73页

作者： He Cheng Xin Liu Xinpei Lu Dawei Liu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuHanHuBeiPeople’s Republic of China IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityShanghai 200240People’s Republic of China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’anPeople’s Republic of China

In this study,the propagation mechanism of plasma jet and some bio-medical applications are investigated by two-dimensional numerical *** key equations of plasma physics and chemistry related with plasma jet are firstly *** simulation results suggest that the sheath forms near the dielectric tube inner surface,which results in the plasma channel to shrink in the radial direction inside the dielectric *** photoionisation of air species plays a crucial role in the transition from the localised discharge to *** Penning ionisation increases the electric conductivity of the plasma channel and facilitates the formation of ring-shaped plasma *** the plasma jet in the open air,electronimpact dissociation of H2O,electron neutralisation of H2O+,as well as dissociation of H2O by O(1D)are found to be the main reactions to produce *** micro plasma jet,the higher ignition voltage as the tube diameter decreased is attributed to the deceasing pre-avalanche electron density inside the *** simulation of plasma treatment of bacteria biofilm indicates that the mean free path of charged species inμm scale permitted the plasma penetrate into the cavity of the biofilm,and the structure of the biofilm results in the non-uniform distribution of ROS and *** simulation of plasma treatment of cells immersed in liquid suggests that the HO2 generated by plasma aqueous species is the only way for superoxide to penetrate cell membrane and damage cytosolic fumarase B.

关键词： propagation mechanism dielectric

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The research and the development of the wide area relaying protection based on fault element identification

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Protection and Control of Modern Power Systems 2016年第1期1卷 95-107页

作者： Xianggen Yin Zhe Zhang Zhenxing Li Xuanwei Qi Wenbin Cao Qian Guo State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhan 430074China

The urgent problem of the relaying protection in the modern AC/DC hybrid connected grid and the development of the wide area communication,the information process and the intelligent technology powerfully promotes the development of the technology of the wide area relaying protection(WARP),which has become a research hotspot that attracts extensive *** from the basic concept of the wide area relaying protection,this paper analyses the advantages,the effects and the functions of the wide area relaying *** two main approaches to realize the wide area protection,which are on-line adaptive setting(OAS)principle and fault element identification(FEI),are introduced in this *** at improving the performance of the backup protection,the research content and the technology demand of the wide area protection are proposed,meanwhile,the basic principle and the algorithm of the fault element identification are *** last,the scheme of the limited wide area relaying protection based on the existing pilot channel of the main protection is discussed.

关键词： Wide area protection Wide area relaying protection On-line adaptive setting Fault element identification The limited wide area protection

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Magnetically controlled saturable reactor core vibration under practical working conditions 17

Magnetically controlled saturable reactor core vibration und...

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17th Biennial IEEE Conference on electromagnetic Field Computation, IEEE CEFC 2016

作者： Tong, Ben Qingxin, Yang Rongge, Yan Lihua, Zhu Province-Ministry Joint Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability Hebei University of Technology Tianjin China Municipal Key Laboratory of Advanced Technology of Electrical Engineering and Energy Tianjin Polytechnic University Tianjin China

ISBN: (纸本)9781509010325

Magnetically controlled saturable reactors (MCSRs) are widely used in high voltage power system, but they make larger vibration and noise than transformers and other types of reactors due to the gapped iron-core structure and magnetic saturation. The main reasons of MCSR vibration are magnetostrictive effect of silicon steel sheet and electromagnetic force between core discs. This paper studies the influence of these two kinds of forces on MCSR vibration, which will be used to help seek new vibration reduction method. Firstly, because MCSRs work in DC bias conditions, multigroup magnetic and magnetostrictive characteristics of silicon steel sheet considering anisotropy under different DC bias excitation conditions are tested. Secondly, based on energy variation principle and virtual work principle, an electro-magneto-mechanical coupled numerical model for MCSRs is established. In order to compare the influence of magnetostrictive effect with electromagnetic force effect on MCSR vibration, vibration accelerations caused by magnetostrictive effect, electromagnetic force and the combination of them are calculated, respectively. From the computation results, it can be seen that the total acceleration is not simple superposition of electromagnetic acceleration with magnetostrictive acceleration. Finally, vibrations of a MCSR under different practical working conditions are tested to prove the validity of the proposed model. © 2016 IEEE.

关键词： Vibration analysis

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