This paper presents a predictive control scheme of DC-link voltage for back-to-back converters based on energy balance modeling. Since the variation of DC-link voltage is affected by the energy mismatch between rectif...
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This paper presents a predictive control scheme of DC-link voltage for back-to-back converters based on energy balance modeling. Since the variation of DC-link voltage is affected by the energy mismatch between rectifier and inverter, the energy distribution in a rectifier-inverter is analyzed. Moreover, in order to calculate the input and output energy in one control period accurately, the grid current is regulated by predictive control and the instantaneous active power consumed by the induction motor is estimated. Then, an equation based on energy balance in one control period is established, and the DC-link voltage can be controlled by solving it. Finally, simulation results show that with the proposed control scheme, the back-to-back converter exhibits both good dynamic and steady-state performances.
The key parameters of SOA (safe operating area) of semiconductor devices are hard to be measured when converter is operating, which is not helpful to protect converter at any time. On the other hand, surplus estimatin...
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The key parameters of SOA (safe operating area) of semiconductor devices are hard to be measured when converter is operating, which is not helpful to protect converter at any time. On the other hand, surplus estimating method is widely used to design the main circuit. In order to guarantee the whole system works safely and improve utilization rate of devices, the concept of SSOA (systematic safe operating area) is presented. By determining the relationship of key parameters between devices and converter, the expression of SSOA is described quantitatively. Then it is implemented as a basic rule to design a back-to-back converter based on IGBT for 55kW induction motor optimally. Rated value of DC-link voltage and grid filter of the system is obtained reasonably as well.
Hard-switching technique under the high voltage and high current is one of main trends of high power inverters. Under this switching mode, the stray parameters of the commutating loops, especially the stray inductance...
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Hard-switching technique under the high voltage and high current is one of main trends of high power inverters. Under this switching mode, the stray parameters of the commutating loops, especially the stray inductance of the DC bus bar, have significant influence on the switching process, electromagnetic interference and component stress of the semiconductor switches. It becomes one of the key points for the safe operation of inverters. Based on an actual 55 kW inverter, the design, simulation and analysis for its bus bar is described in this paper. The bus bar model is built with the method of Partial Element Equivalent Circuit (PEEC), and the stray parameters are extracted from PEEC model and applied in the circuit simulation. Compared with the experimental results, the modeling validity is proved, and the simplified modeling process and design principles for complex physical bus bar are presented.
This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straight-blade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT)An attempt ...
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This paper presents an analysis on the performance of vertical axis wind turbine of two types, namely straight-blade vertical axis wind turbine(SB-VAWT) and twisted-blade vertical axis wind turbine(TB-VAWT)An attempt of this simulation is to identify which type performs better in the same wind conditions and swept areaThree-dimensional computational fluid dynamics(CFD) was adopted in this analysis, after solid models of them were generatedPreliminary results of torque, power and aerodynamics in the fluid field were obtained for discussionFinally, there provided some guidance for future wind tunnel tests.
The implementation of non-communication protection of double circuit line systems based on two independent relays has disadvantages like information shareless,complex connection and lack of economic. This paper resear...
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A substation three-phase nonlinear state estimation method based on zero impedance branches is presented in order to eliminate topology and analogy errors at substation level and accordingly enhance the control center...
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Standardization is the development tendency of information exchange among control centers. Based on the standard in IEC 61970, an information exchange model suitable for coordinated automatic voltage control (CAVC) am...
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Standardization is the development tendency of information exchange among control centers. Based on the standard in IEC 61970, an information exchange model suitable for coordinated automatic voltage control (CAVC) among multi control centers is proposed. Firstly, the contents of information flow of CAVC is analyzed and the definition of coordinated control model for information exchange is given;then the common information model is extended and a standardized information model for CAVC is designed;and then based on component interface specification, a standardized information exchange interface for CAVC is designed and its architecture for information exchange as well as its information exchange procedure are given. The presented information exchange model possesses wide application prospect in the implementation of information exchange among multi CAVC control centers for future smart grids.
Grid-connected LCL filter of voltage source PWM rectifier (VSR) can not only reduce the values of inductance, improve the system dynamic response, but also reduce the cost. However, LCL filter brings stability problem...
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Grid-connected LCL filter of voltage source PWM rectifier (VSR) can not only reduce the values of inductance, improve the system dynamic response, but also reduce the cost. However, LCL filter brings stability problem if no damping method is adopted. In order to guarantee the stability and high power factor of VSR at the same time, active damping control method rather than reactive damping method is required. Nowadays, the study on LCL filter is just for two-level VSR. In this paper, parameter design and damping method are being placed in three-level VSR for widely use. For a three-level PWM rectifier, a new parameter design method as well as active damping method is proposed and verified by Matlab-Simulink simulation and experiment.
In the annular power distribution system, short-circuit fault of bus-bars will do fatal harm to aircraft, and it is necessary to protect the ring-net bus-bars. Protecting bus-bars has to meet the requirements that pro...
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Five-level active neutral-point-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional neutral-point clamped (NPC) converters and flying-capacitor (FC) converters. Its dc...
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Five-level active neutral-point-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional neutral-point clamped (NPC) converters and flying-capacitor (FC) converters. Its dc-link is subdivided into two equal parts and the main problem is the neutral-point (NP) potential balancing. In this paper, a NP potential balancing algorithm based on zero-sequence voltage injection is presented. By calculating the NP currents of all key zero-sequence voltages, the most appropriate zero-sequence voltage is selected to generate the demanded NP current. Moreover, by further limiting the span of injected zero-sequence voltages, the NP balancing algorithm can make the two IGBTs connected in series operate at fundamental frequency. A three-phase five-level ANPC inverter prototype was built up and experimental results are presented to verify the validity of this algorithm.
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