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International Conference on Electrical Machines

作者： Mingjie He Wei Xu Caiyong Ye Wei Hua State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China School of Electrical Engineering Southeast University Nanjing China

Doubly salient permanent magnet machine (DSPMM) enjoys the advantages of high torque density, simple rotor structure, high reliability, etc. However, the air-gap flux density is difficult to regulate due to that the air-gap magnetic field is produced only by permanent magnets (PMs). Thus, this paper proposes a hybrid excited asymmetric-stator-pole doubly salient machine (HE-ASPDSM) and its air-gap flux density can be regulated easily by controlling the excitation current of field winding. The topologies and operation principle of the HE-ASPDSM are studied firstly based on modern winding theory and two-dimension finite element analysis (2D FEA). Then, the comparison of no-load flux linkage, back electric magnetomotive force (EMF) and air-gap flux density of different topologies is made. Besides, the expression and harmonic components of air-gap flux density are also derived based on mathematical analysis. And then, the influence of key design parameters on the cogging torque, flux regulation ability, electromagnetic torque, losses and efficiency is investigated in details. Finally, the analysis of main performance indexes is performed based on the proposed 12/7 (stator/rotor poles) HE-ASPDSM. It indicates that the proposed 12/7 HE-ASPDSM has strong air-gap flux regulation ability.

关键词： Air-gap flux regulation Hybrid excited asymmetric-stator-pole doubly salient machine (HE-ASPDSM) Mathematical analysis Two-dimension finite element analysis (2D FEA)

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Improved active and reactive power control for symmetrical bipolar MMC-HVDC systems during DC side PTG fault

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The Journal of engineering 2017年第13期2017卷 885-891页

作者： Kai Hu Lei Lin Zhen He Chen Xu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan People's Republic of China

Symmetrical bipolar modular multilevel converter (MMC) combined with two monopolar MMCs has many benefits, such as high voltage and power level and flexible operation modes. However, the active power and reactive power of the MMC stations will reduce to half when direct current (DC) side pole-to-ground (PTG) happens, which will cause large disturbance to the alternating current (AC) grid. This study focuses on an improved active and reactive power control method for a symmetrical bipolar MMC-high-voltage direct current system during PTG fault. The healthy pole is adjusted to overload mode while the faulty pole switches to STATCOM mode. To maximise the utilisation of the operation region for healthy pole, it is analysed based on multi-restrictions of transformer capacity, arm current, sub-module (SM) voltage balance, SM voltage fluctuation and DC line overload capacity. By means of the improved active and reactive power control method, the disturbance to the AC grid is minimised. The feasibility of the proposed control method is verified by PSCAD/EMTDC simulation.

关键词： HVDC power convertors HVDC power transmission power transmission control reactive power control fault diagnosis power transmission faults static VAr compensators power overhead lines control method DC line overload capacity SM voltage fluctuation faulty pole overload mode healthy pole direct current system symmetrical bipolar MMC-high-voltage improved active power alternating current grid pole-to-ground MMC stations reactive power flexible operation modes power level high voltage symmetrical bipolar modular multilevel converter PTG fault symmetrical bipolar MMC-HVDC systems

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Parameter Optimization of DOCR and FCL in Microgrids Based on Grey Wolf Optimizer

Parameter Optimization of DOCR and FCL in Microgrids Based o...

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International Universities Power engineering Conference

作者： Jiang Yi Dongyuan Shi State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security and High Efficiency Key Laboratory Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of Advanced Electromagn

ISBN: (纸本)9781538629116

The operating time of directional overcurrent relays (DOCRs) can be reduced, while protection coordination is achieved, by setting the time dial setting (TDS) and pickup current of DOCRs. However, in the microgrids, the dual operating modes (grid-connected and islanded) and the introduction of distributed generations (DGs) bring some problems to coordination of DOCRs, due to changes in short-circuit levels. To limit the fault current levels and the effects of DGs on protection coordination, fault current limiters (FCLs) have been proposed. This paper employs grey wolf optimizer (GWO) to optimize the setting parameters of DOCRs and the values of FCLs not only in microgrids' two operating modes, but also under two different kinds of protection coordination schemes. The comparison between optimized results obtained by five algorithms demonstrates the outstanding performance of GWO in low dimensional optimization problems and its potential for improvement.

关键词： Directional overcurrent relays Grey wolf optimizer Microgrids Metaheuristic algorithm Protection coordination

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Amplitude death in globally coupled oscillators with time-scale diversity

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Physical Review E 2018年第6期98卷 062209-062209页

作者： Wei Zou Meng Zhan Jürgen Kurths School of Mathematical Sciences South China Normal University Guangzhou 510631 People's Republic of China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China Potsdam Institute for Climate Impact Research Telegraphenberg Potsdam D-14415 Germany Institute of Physics Humboldt University Berlin Berlin D-12489 Germany Saratov State University 4410012 Saratov Russia

We analyze amplitude death (AD) in large systems of globally coupled oscillators with randomly distributed time scales. We show that the distribution of characteristic eigenvalues of a large but finite system is well approximated by the continuous and discrete spectra of the system in the thermodynamic limit. The stability analysis from the continuous and discrete spectra of the infinite system provides a fairly accurate prediction for the onset of AD in the large finite system. We prove the argument by examining the stability of AD in a paradigmatic system of coupled Stuart-Landau limit cycles with mismatched time scales. The proposed technique is extended to systems of globally coupled nonlinear oscillators of a general form with time-scale diversity, which is verified in coupled chaotic Rössler oscillators. Our study provides analytical insight into the understanding of the emergence of AD in populations of globally coupled dynamical systems.

关键词： Coupled oscillators

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Optimised design of DC-side smoothing reactors in meshed multi-terminal HVDC systems based on symmetrical bipolar modular multilevel converter

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The Journal of engineering 2017年第13期2017卷 1225-1231页

作者： Chengzhu Li Lei Lin Zhen He Chen Xu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan People's Republic of China

Compared with the radial modular multilevel converter multi-terminal direct current (MMC-MTDC) system, the meshed system is with higher power supply reliability and flexibility. However, its vulnerability against DC fault is a significant issue. When a DC fault occurs, the DC-side smoothing reactor will limit rising rate of the fast-developing fault current, and then DC current breakers can isolate the fault. This paper proposes a method to optimise the design of smoothing reactors in meshed MTDC system. Firstly, fault characteristics of fault currents and the whole system based on different smoothing reactors are proposed through theoretical analysis. Then, the simplified calculation steps of fault currents at each point in the meshed system are introduced. Thus, the range of the optimal smoothing reactor can be deduced through comparing the rising rates of each current based on the expected post-fault system states. Finally, the simulation model based on PSCAD/EMTDC is carried out to prove the correctness of the proposed method, and visually shows the distinct operating states of the system with different smoothing reactor at fault time.

关键词： HVDC power convertors reactors (electric) optimisation reliability fault currents PSCAD-EMTDC simulation model post-fault system meshed MTDC system fault isolation DC current breaker fault current calculation DC fault vulnerability power supply reliability MMC-MTDC system radial modular multilevel converter multiterminal direct current system symmetrical bipolar modular multilevel converter meshed multiterminal HVDC system DC-side smoothing reactor optimised design

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Paralleled Three-Phase Four-Leg Inverters for Reduction of Common Mode Current and Common Mode EMI

Paralleled Three-Phase Four-Leg Inverters for Reduction of C...

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Annual Conference of the IEEE Industrial Electronics Society

作者： Zewei Shen Dong Jiang Hanxiang Wang Ronghai Qu Xuejun Pei State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

This paper introduces a paralleled three-phase four-leg inverters and the corresponding pulse width modulation (PWM) method for the purpose of reduction the common mode current (CMC) and common mode electromagnetic interference (EMI). Considering the control principle of three-phase four-leg to limit the common mode voltage and the characteristic of paralleled inverters, the simple PWM scheme for paralleled three-phase four-leg inverters can be deduced. In the modified topology, the low frequency and high frequency models can be set up to determine the load parameters of the extra phase. The results based on MATLAB SIMULINK and experiments are provided to validate the proposed method.

关键词： Inverters Pulse width modulation electromagnetic interference Switches Clamps Topology

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Optimal current reference with maximum thrust criterion for linear induction machine based deadbeat control

Optimal current reference with maximum thrust criterion for ...

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Annual Conference of Industrial Electronics Society

作者： Jianqiao Zou Wei Xu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

Due to the current constraint of linear induction machine (LIM) and voltage constraint of inverter, the output thrust of LIM is limited. So, in order to make LIM output thrust as large as possible within current and voltage limit, firstly, the maximum thrust per ampere (MTPA) is used to achieve maximum thrust with limited current in low speed. Secondly, with the speed of LIM increasing, the voltage limit of inverter has to be considered by the method of field-weakening. And similar to the concept of MTPA, the maximum thrust per volt (MTPV) is deduced for achieving maximum thrust within the voltage constraint of inverter. Finally, the deadbeat control method is applied to LIM for high tracking performance, and both simulation and experiments demonstrate the effectiveness of this proposed control strategy.

关键词： Trajectory Inverters Induction machines Torque Inductance Mathematical model Angular velocity

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Learning from time-synchronized power system measurements with rare anomalous event records to detect PMU data manipulation attacks

Learning from time-synchronized power system measurements wi...

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IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Jingyu Wang Dongyuan Shi State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781538614280

PMU data manipulation attacks (DMA) which maliciously modify the synchrophasor measurements in power systems, is an emerging type of cyber-attack aiming to mislead the control center into taking erroneous control actions. Widespread application of PMU produces a vast amount of time-synchronized historical operating data, making it possible to turn to machine learning approaches to detect the attacks. However, anomalous events occur rarely in practice. To construct a balanced training dataset, where normal and anomalous instances need to be evenly extracted and labeled from historical operating records, is sure to cost plenty of human efforts and may introduce uncontrollable experience errors. In this paper, we design a novel detection model with Synthetic Minority Over-sampling TEchnique (SMOTE)-based data augmentation and Edited Nearest Neighbors (ENN)-based data cleaning technique to reconstruct the imbalanced training dataset into a balanced one to train the subsequent XGBoost classifier. Experiments show that although rare anomalous historical event records are needed, our model is still able to effectively detect out DMAs in power systems.

关键词： Phasor measurement units Transmission line measurements Power systems Training Data models Cleaning Classification algorithms

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Model predictive current control of brushless doubly-fed machine for stand-alone power generation system

Model predictive current control of brushless doubly-fed mac...

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Annual Conference of Industrial Electronics Society

作者： Wei Xu Jianping Gao Yi Liu Kailiang Yu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

To achieve good steady-state performance and quick dynamic response, one model predictive current control (MPCC) method is proposed in this paper to replace the traditional proportional-integral (PI) controller to regulate the control winding (CW) current of brushless doubly-fed machine (BDFM) for stand-alone power generation system. The MPCC is developed based on the unified reference frame dq model of the BDFM. Simulations under several typical conditions are carried out to verify the effectiveness of MPCC. It is proven that MPCC can get a better CW current response than PI controller and can produce better effects on the output voltage of power winding (PW). Besides, MPCC is simpler than PI current control loop, because no parameters need to be tuned for MPCC.

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Power system joint energy and reserve scheduling model considering variable speed pumped hydro storage for mitigating wind curtailment

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IOP Conference Series: Earth and Environmental Science 2019年第1期354卷

作者： T T Zheng Y W Li P W Yang X L Chen R Zheng S H Miao H Ji H R Yin 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 large-scale integration of wind power brings great challenges to power system secure and economic operation. In order to address this challenge, the variable speed pump storage hydropower plant (VS-PSHP) technology and demand response technology have addressed a lot attention. In this paper, the coordination of the thermal power generator, the wind power plant, the VS-PSHP and multi-type flexible loads are considered, and a day-ahead and real-time coordinated scheduling model are proposed. The proposed model can formulate the generation, contingency reserve and power distribution factor schedules simultaneously. Numerical simulation results indicate that the coordination of VS-PSHP and multi-type flexible loads can increase the system operation economic and mitigating the wind power curtailment. The results also show that the VS-PSHP is good at providing contingency reserve, and the participation of VS-PSHP can lead to a relatively lower total system operation cost compared to the participation of fixed speed pump storage hydropower plant (FS-PSHP).

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