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183 results on '"Ji, Yanchao"'

3. Improved Control Method of Microgrid for the Better Dynamic Characteristics

Author

Wang, Xuejie, Ji, Yanchao, Wang, Jianze, Wang, Yuanjun, Qi, Lei, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zhang, Junjie James, Series Editor, Chang, Jia-Wei, editor, Yen, Neil, editor, and Hung, Jason C., editor

Published
2021
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9. Research on distribution network reconfiguration based on microgrid

Author

Wang, Xuejie, Ji, Yanchao, Wang, Jianze, Gao, Yang, and Qi, Lei

Abstract

Micro-grids have been considered as a vital part of power system. The distribution system is gradually showing the characteristics of multi-source initiative. The distribution network reconfiguration with microgrid changes the topology of the network by controlling the state of the switch, and optimizes the predetermined indicators under the premise of safe, economic and stable operation. This paper describes a hierarchical distribution network reconfiguration strategy with microgrid, which can reduce the number of operation of the switch and the network loss. This strategy ensures rapid power supply recovery. In the process of reconstruction, this paper uses the immune clonal selection differential evolution algorithm. The simulation examples are included to display the performance of the proposed method.

Published
2024
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14. A Novel Detection and Localization Approach of Open-Circuit Switch Fault for the Grid-Connected Modular Multilevel Converter

Author

Jin, Yu, Xiao, Qian, Jia, Hongjie, Ji, Yanchao, Dragicevic, Tomislav, Teodorescu, Remus, Blaabjerg, Frede, Jin, Yu, Xiao, Qian, Jia, Hongjie, Ji, Yanchao, Dragicevic, Tomislav, Teodorescu, Remus, and Blaabjerg, Frede

Abstract

The open-circuit fault detection and localization (FDL) technique can improve the reliability of the modular multilevel converter (MMC). However, the conventional software-based FDL methods usually have a heavy computation burden or a limited localization speed. This paper proposes a simplified and fast software-based FDL approach for the grid-connected MMC. Firstly, the errors between the measured state variables (the output current and the circulating current) and their estimated values are calculated. By comparing these errors with their threshold values, the switch fault can not only be detected, but also be localized to the specific arm. Then, the capacitor voltages in this faulty arm are collected, and the submodule (SM) with the highest capacitor voltage is selected. To confirm the switch fault in this SM, a modified Pauta criterion is presented to check the abnormal voltage data. As a result, the computation burden of the proposed software-based FDL approach is significantly reduced, and the faulty SM can be localized in a short period. Simulation and experimental results verify that the proposed approach can effectively detect and locate different open-circuit faults, and it is immune to the step of power references.

Published
2022

17. A novel sliding-discrete-control-set modulated model predictive control for modular multilevel converter

Author

Jin, Yu, Xiao, Qian, Jia, Hongjie, Mu, Yunfei, Ji, Yanchao, Dragieevic, Tomislav, Teodorescu, Remus, Blaabjerg, Frede, Jin, Yu, Xiao, Qian, Jia, Hongjie, Mu, Yunfei, Ji, Yanchao, Dragieevic, Tomislav, Teodorescu, Remus, and Blaabjerg, Frede

Abstract

Model predictive control (MPC) method has been recognized as one of the most promising technologies for the modular multilevel converter (MMC) due to the fast dynamic response and its simple realization. However, conventional finite control set (FCS) MPC methods for MMC are facing some challenges, such as high computation burden, poor steady-state performance, dependence on weighting factors, and variable switching frequency. In order to solve these problems, a novel sliding-discrete-control-set (SDCS) modulated MPC (MMPC) is proposed for MMC in this paper. Based on the adaptive search step in the output current control, only three control sets are evaluated in each period. In addition, the independent circulating current controller is applied in the proposed MMPC method. With the circulating current controller, the circulating currents are well regulated, and the arm capacitor voltage balancing is realized by circulating current injection. As a result, there is no weighting factor involved in the proposed MMPC method. Compared with the conventional MPC methods, the proposed method obtains a fixed switching frequency in each submodule (SM) and a low comparable computation burden. Simulation and experimental results verify the effectiveness of the proposed method.

Published
2021

18. A Dual-Layer Back-Stepping Control Method for Lyapunov Stability in Modular Multilevel Converter based STATCOM

Author

Jin, Yu, Xiao, Qian, Jia, Hongjie, Mu, Yunfei, Ji, Yanchao, Teodorescu, Remus, Dragicevic, Tomislav, Jin, Yu, Xiao, Qian, Jia, Hongjie, Mu, Yunfei, Ji, Yanchao, Teodorescu, Remus, and Dragicevic, Tomislav

Abstract

With the high penetration of the power electronic loads in the grid, the stability of static synchronous compensator (STATCOM) devices are greatly challenged. However, the conventional control methods for the modular multilevel converter (MMC) based STATCOM only consider the stability with small signal disturbances. This paper proposes a novel dual-layer back-stepping control (BSC) for the MMC based STATCOM. In the first layer, the BSC aims to regulate the sum of the capacitor energy and the reactive output current. In the second layer, the BSC aims to control the circulating current. Therefore, the proposed method possesses a fast dynamic response and accurate tracking with the Lyapunov stability of the MMC based STATCOM. Compared with the arm-control-based back-stepping control for MMC based inverters, the proposed method has a simplified structure and a reduced computation burden. In addition, the proposed method realizes the decoupled control between the output current and the circulating current. The simulation and experimental results verify the effectiveness of the proposed method. In addition, its robustness towards different circuit parameters and the operation ability under unbalanced grid fault is also verified.

Published
2021

44. Research on Control Strategy for a Multiple Grid-Connected-Inverter System

Author

Wang Jianze, Peng Haojie, Xie Wenhao, and Ji Yanchao

Subjects
Computer science, 020209 energy, 020208 electrical & electronic engineering, Automatic frequency control, Longitudinal static stability, Hardware_PERFORMANCEANDRELIABILITY, 02 engineering and technology, AC power, Electric power system, Computer Science::Systems and Control, Control theory, 0202 electrical engineering, electronic engineering, information engineering, Voltage droop, Transient (oscillation), Power control, Voltage
Abstract

In this paper, the static stability of droop control for a multiple grid-connected-inverter system is analyzed. The equations of droop coefficient to power capacity are derived. However, inverters based on conventional droop control have no inertia support for the power system. Therefore, a modified strategy adding virtual synchronous generator control to the conventional static droop approach is proposed. The inertia and damping for inverters are increased to suppress the variation of voltage frequency, which provides a perfect static stability and transient performance. After that, small-signal models are built to compare the frequency transient of these two control strategies. Finally, simulation experiments verify the effectiveness and validity of the modified strategy.

Published
2016

47. Power fluctuation alleviation using cascade STATCOMs with energy storages for wind farm applications

Author

Li Ning-ning, Liu Yi-qi, Ji Yanchao, Wang Jianze, and Shen Ke

Subjects
Stand-alone power system, Engineering, Wind power, Control theory, business.industry, Cascade, Inverter, AC power, business, Maximum power point tracking, Power control, Power (physics)
Abstract

In this paper, a cascade STATCOM with battery energy storages for wind power applications is presented. Meanwhile, a coordinate control strategy is proposed for this inverter system in order to alleviate both active and reactive power fluctuation in a wind power generation system. The SoC of each battery is directly controlled using PI controller and zero sequence voltage is injected so as to obtain balanced state-of-charge (SoC). A time constant T is involved to identify the power reference from the cascade inverter, this time constant is determined by considering both the SoC of each battery and the required power of the wind farm. A nine-zone plot is presented to simplify the above process for deriving the parameter T. A simulation model based on MATLAB/Simulink is developed to validate the proposed method. At the same time, a 10 kW prototype is implemented and experimental results are given to demonstrate the feasibility of the approach.

Published
2014

50. Torque close-loop control of a novel soft starter of induction motor

Author

Lv Guangqiang, Ji Yanchao, Hu Fei, and Li Qiang

Subjects
Chopper, Engineering, Stall torque, Direct torque control, Torque motor, Control theory, business.industry, Motor soft starter, Thyristor, Control engineering, business, Induction motor
Abstract

This paper describes a novel topology of soft starter for induction motors. Unlike the thyristerized soft starter, the proposed circuit configuration utilizes the self-commutated device to replace the thyristor as the switch on the supply line. The operating principle of the control system is analyzed. The transient process during starting has been studied using a presented mathematical model which is general enough to simulate most of the ac chopper control system as applied to induction motors. The dynamic performance of starting current and torque pulsations can be improved by the simple control strategy, which is the duty cycle of switches is regulated by PI controller. The experimental setup, which is realized with a controller based on the DSP, is presented. The corresponding experimental results obtained for a squirrel-cage induction motor prove the validity of the proposed soft starter.

Published
2013

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