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Ma W.,National Key Laboratory for Vessel Integrated Power System Technology
APAP 2011 - Proceedings: 2011 International Conference on Advanced Power System Automation and Protection | Year: 2011

The vessel integrated power system (IPS) is the third revolution in the naval vessel power which has evolved from wind power to steam power and then from steam power to nuclear power, marking the trend of naval vessel power. The first-generation IPS has been widely applied to engineering in many countries. However, there are some defects in it such as huge volume, heavy weight and low compatibility when the first-generation IPS is used in light ships, because its power density is limited by the properties of the electromagnetic materials, power electronics, etc. This paper has presented the concept and typical architecture of the second-generation IPS and its technical advantages, introduced several key technologies concerning the second-generation IPS that need a breakthrough according to the current technical level, and pointed out direction of the research and engineering application of the second-generation IPS. © 2011 IEEE. Source


Cai X.,Huazhong University of Science and Technology | Cai X.,Fujian University of Technology | Wu Z.,National Key Laboratory for Vessel Integrated Power System Technology | Sun L.,Xian Jiaotong University
2014 17th International Conference on Electrical Machines and Systems, ICEMS 2014 | Year: 2015

Since many Cascaded H-bridge multilevel (CHBML) inverters that are applied to drive high voltage machines can't transmit electric energy reversely, the electric energy transmitted from the machines may damage the inverters. This paper presents a transfer function to analyze the electromagnetic torque, when the load torque changes suddenly. Based on the achievements, the electric energy that flows between the machine and the inverter can be calculated. And then, a method is proposed to prevent the reversion of the direction of energy flow. Furthermore, the transfer function can be used to guide the design of the control system of induction machine. Simulation results verify the transfer function and the presented method. © 2014 IEEE. Source


Shi Q.,Xian Jiaotong University | Wang G.,National Key Laboratory for Vessel Integrated Power System Technology | Fu L.,National Key Laboratory for Vessel Integrated Power System Technology | Yuan L.,National Key Laboratory for Vessel Integrated Power System Technology | Huang H.,National Key Laboratory for Vessel Integrated Power System Technology
IECON Proceedings (Industrial Electronics Conference) | Year: 2013

With the increasing number of variable speed wind turbine generators connect to electrical grid, it is necessary for wind turbines to provide inertia support when the grid frequency drops. Because of its unclear physical concept and time-consuming calculation when the detail simulation model is adopted to deal with the virtual inertia control of the directly-driven wind turbine with permanent-magnet synchronous generator (D-PMSG), it is difficult to design the control scheme and analyze the frequency dynamic response of power systems according to the simulation results. Aiming at the physical essence of wind turbine virtual inertia control, this paper presents a properly-simplified state-space averaging model of the wind power integrated system (WPIS). The model can reflect the dynamic process of virtual inertia control. Based on the model, a linearized model is derived from equation transformation so as to get information about small signal stability. The state-space averaging model established in this paper can provide the technical means for designing the control scheme of virtual inertia control and analyzing the frequency dynamic response of the WPIS. The results of simulation tests have verified the effectiveness of the state-space averaging model. © 2013 IEEE. Source


Cai X.,Huazhong University of Science and Technology | Cai X.,Fujian University of Technology | Wu Z.,National Key Laboratory for Vessel Integrated Power System Technology | Li Q.,Zhejiang University | Wang S.,National Key Laboratory for Vessel Integrated Power System Technology
Journal of Power Electronics | Year: 2016

Cascaded H-bridge multilevel (CHBML) inverters usually include a large number of isolated dc-voltage sources. Some faults in the dc-voltage sources result in unequal cell dc voltages. Unfortunately, the conventional phase-shifted carrier (PSC) PWM method that is widely used for CHBML inverters cannot eliminate low frequency sideband harmonics when the cell dc voltages are not equal. This paper analyzes the principle of sideband harmonic elimination, and proposes an improved PSCPWM that can eliminate low frequency sideband harmonics under the condition of unequal dc voltages. In order to calculate the carrier phases, it is necessary to solve transcendental equations for low frequency sideband harmonic elimination. Therefore, an approach based on the artificial bee colony (ABC) algorithm is presented in this paper. The proposed PSCPWM method enhances the reliability of CHBML inverters. The proposed PSCPWM is not limited to CHBML inverters. It can also be applied to other types of multilevel inverters. Simulation and experimental result obtained from a prototype CHBML inverter verify the theoretical analysis and the achievements made in this paper. © 2016 KIPE. Source


Cai X.-J.,Huazhong University of Science and Technology | Cai X.-J.,Fujian University of Technology | Cai X.-J.,National Key Laboratory for Vessel Integrated Power System Technology | Wu Z.-X.,National Key Laboratory for Vessel Integrated Power System Technology | And 2 more authors.
Energies | Year: 2015

High-voltage cascaded H-bridge multilevel (CHBML) inverters usually include many isolated dc voltage sources. Some dc source faults result in a drop in the dc voltage, thereby leading to unequal cell dc voltages. On the other hand, the differences in cell dc source parameters result in unequal dc voltages too. At present, riding through the faults of dc sources and operating under the condition of unequal dc voltages are required to improve the reliability of CHBML inverters. Unfortunately, the conventional phase-shifted carrier pulse width modulation (PSCPWM), which is widely used for CHBML inverters, cannot eliminate low-frequency sideband harmonics when cell dc voltages are not equal. This paper analyzes the principle of sideband harmonic elimination, and proposes an improved PSCPWM based on the particle swarm optimization algorithm. This modulation technique eliminates low-frequency sideband harmonics by calculating and regulating the carrier phases according to different cell dc voltages. The proposed PSCPWM enhances the reliability of the CHBML inverter and extends the range of its application. Simulation and experimental results obtained from the prototype of the CHBML inverter verify the theoretical analysis and the achievements made in this paper. © 2015 by the authors. Source

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