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Jianyong Zheng,Yi Pan,Fei Mei,Huiyu Miao,Kedong Zhu,Haoyuan Sha 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.1
Traditional fault diagnosis for a high-voltage circuit breaker (HVCB) encounters the following problems: the fault features extracted by traditional shallow models is of weak expression ability, and the accuracy of fault identification can be affected by the lack of labeled training samples. To overcome these problems, we present a new approach for HVCB mechanical fault diagnosis based on a deep belief network (DBN) and a transfer learning strategy. This approach uses a DBN to achieve the deep mining and adaptive extraction of the inherent features of sample data, and combines the transfer learning method to improve the accuracy of the fault diagnosis model, which uses a large amount of selective auxiliary data to augment the tiny amount of target data learning by adjusting the weight of training samples. The target sample data are obtained by collecting the coil current signal of the HVCB from fault simulation experiments, and the auxiliary sample data are obtained through simulation based on the electromagnetic system mathematical model of the HVCB spring mechanism. The experimental results show that compared with the traditional feature extraction and fault diagnosis method, the DBN approach combined with transfer learning can achieve stronger feature learning and generalization ability
Novel Switched-Inductor Quasi-Z-source Inverter
Kai Deng,Jianyong Zheng,Jun Mei 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1
A novel switched-inductor quasi-Z-source inverter is proposed in this study. Compared with classic topologies, the boost ability of the proposed topology is strengthened. The voltage stress of the capacitors, diodes, and power devices are reduced, and the current ripple of the DC voltage source is suppressed. Conversion efficiency is also improved. The operation principle of the proposed topology is analyzed in detail and compared with that of similar topologies. The feasibility of the proposed topology is verified by simulations and experiments on a laboratory prototype.
Adapative Load Anti-islanding Method of Large Distributed Photovoltaic Power Grid
Xiaoyu Chen,Jianyong Zheng,Jun Mei 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.8
A large number of distributed photovoltaic power grid, islanding problems become more prominent. This paper first analyzes some existing anti-islanding scheme, and analyzes its advantages and disadvantages. Then, this paper proposes adaptive anti-islanding scheme by using the load, i.e. load automatic switching, changing the characteristics of the whole load, make the passive anti-islanding without dead-zone. Then using PSCAD simulation of the program, to verify the usefulness of the proposed scheme. To minimize the distributed photovoltaic power grid investment, saving the scheme relies on a new generation of distributed photovoltaic (pv) grid interface device. Then the paper introduces the overall structure and function of the device configuration, the device not only can solve the problem of area of backup protection, also save on investment, convenient for on-site equipment installation and maintenance, for the widespread promotion of distributed photovoltaic power grid to lay a solid foundation.
Control Method for Fault-Tolerant Active Power Filters
Chenyu Zhang,Jianyong Zheng,Jun Mei,Kai Deng,Fuju Zhou 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3
New direct and indirect current control methods for a fault-tolerant active power filter topology are presented in this paper. Since a three-phase four-switch topology has a phase bridge current which cannot be directly controlled, a hysteresis control method in the α-β plane which controls the three-phase current in the two-phase stationary coordinate system is proposed. The improved SVPWM algorithm is able to eliminate the operation of the trigonometric functions in the traditional algorithm by rotating the α-β coordinates and alternating the sequence of the output vectors, which in turn simplifies the algorithm and reduces the switching frequency. The selection of the DC-side reference voltage and DC-side capacitor equalization strategy are also discussed. Simulation and experiments demonstrate that the proposed control method is correct and feasible.
Control Method for Fault-Tolerant Active Power Filters
Zhang, Chenyu,Zheng, Jianyong,Mei, Jun,Deng, Kai,Zhou, Fuju The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3
New direct and indirect current control methods for a fault-tolerant active power filter topology are presented in this paper. Since a three-phase four-switch topology has a phase bridge current which cannot be directly controlled, a hysteresis control method in the α-β plane which controls the three-phase current in the two-phase stationary coordinate system is proposed. The improved SVPWM algorithm is able to eliminate the operation of the trigonometric functions in the traditional algorithm by rotating the α-β coordinates and alternating the sequence of the output vectors, which in turn simplifies the algorithm and reduces the switching frequency. The selection of the DC-side reference voltage and DC-side capacitor equalization strategy are also discussed. Simulation and experiments demonstrate that the proposed control method is correct and feasible.
Novel Switched-Inductor Quasi-Z-source Inverter
Deng, Kai,Zheng, Jianyong,Mei, Jun The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1
A novel switched-inductor quasi-Z-source inverter is proposed in this study. Compared with classic topologies, the boost ability of the proposed topology is strengthened. The voltage stress of the capacitors, diodes, and power devices are reduced, and the current ripple of the DC voltage source is suppressed. Conversion efficiency is also improved. The operation principle of the proposed topology is analyzed in detail and compared with that of similar topologies. The feasibility of the proposed topology is verified by simulations and experiments on a laboratory prototype.
Mei Fei,Mei Jun,Zheng Jianyong,Wang Yiping 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.4
On-line monitoring system is important for high voltage vacuum circuit breakers (HVCBs) in operation condition assessment and fault diagnosis. A distributed multilayer system with client/server architecture is developed on rated voltage 10kV HVCB with spring operating mechanism. It can collect data when HVCB switches, calculate the necessary parameters, show the operation conditions and provide abundant information for fault diagnosis. Ensemble empirical mode decomposition (EEMD) is used to detect the singular point which is regarded as the contact moment. This method has been applied to on-line monitoring system successfully and its satisfactory effect has been proved through experiments. SVM and FCM are both effective methods for fault diagnosis. A combinative algorithm is designed to judge the faults of HVCB’s operating mechanism. The system"s precision and stability are confirmed by field tests.
An Improved MMC Control Strategy with Single-Phase to Ground Fault-Tolerance Capability
Huiyu Miao,Jun Mei,Jianyong Zheng,Chenyu Zhang,Chao Zhu,Tian Ma,Fei Mei 대한전기학회 2016 Journal of Electrical Engineering & Technology Vol.11 No.5
In this paper, an improved modular multilevel converter (MMC) control strategy based on one-cycle control (OCC) is proposed. With the introduction of OCC, the stability, rapidity and disturbance rejection of MMC is greatly improved. Based on the volt-second equilibrium, the control is distributed to every single submodule (SM). For further stability, an unbalanced OCC strategy is designed based on feed-forward control for negative sequence voltage with no need for measuring the positive and negative current sequence, considering single phase to ground fault and the second harmonic ripples of the DC voltage. As the switch frequency of every SM is different, the virtual loop mapping is used in this paper to balance the capacitor voltage with less hardware dependence. And a new simplified structure is also proposed with RS flip-flop abandoned. At last, simulation and experiment results prove the validity of the control theory.