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Distributed generation provides a new opportunity for modern power supply, and also challenges the safe operation of the existing power system. This paper studied on site selection and protection configuration of distributed power supply in microgrid system, mainly including the objective function and constraint conditions of distributed power source siting in microgrid system, the revision of distributed...
Distributed generation provides a new opportunity for modern power supply, but it also impacts on the operation and management of distribution network. Distributed power connected to the distribution network has changed the mode of operation of the distribution network from the original radiation type to a multiple power supplies network. The power flow direction of the traditional distribution network...
The solar energy has an enormous developing application capacity as one kind of green renewable energy source which can be continuously used forever. But there is tremendous relationship between photovoltaic cells output characteristics and the change of external environmental factors, currently the efficiency of PV cells is not only low but also expensive on a large scale of production. It is very...
Due to the large number of distributed generation and nonlinear components in the Photovoltaic (PV) System, Voltage condition at the point of common coupling (PCC) faces severe challenges. Evaluation of the PCC voltage stability has become critical to the steady operation of the PV system. PV system is a typical nonlinear nonautonomous system, and bifurcation theory, as one the effective ways to solve...
Experimental imitation platform of the wind energy generation system with direct-driven permanent magnet synchronous generators (PMSG) was designed to simulate wind power on-site in a laboratory environment and realize controlled natural wind environment for 10kw wind turbine simulation system. The platform consists of the IPC, asynchronous drag motor, frequency converter, PMSG, power electronic conversion...
The influence of dead-time on three-phase voltage source inverter output voltage using SVPWM modulation is analyzed in the paper. In order to reduce the voltage distortion, current harmonics and torque ripple caused by the dead time effects, dead-time compensation is needed. This paper presents the method of estimating current vector angle indirectly by power-factor angle, and gives the relationship...
The imbalance of neutral-point potential is an internal problem with three-level inverters. To solve this problem, this paper proposes a novel neutral-point potential control method by injecting zero-sequence voltage, and gives the valid criteria for selecting which zero-sequence voltage to use. Simulations and experiments validate that the imbalance of neutral-point potential could be controlled...
It is very important to select hub nodes or key junctions before urban traffic signal control system (SCOOT or SCATS) divides control sub-areas. Usually, traffic flow and link numbers are used as indexes to find out which hub nodes are in urban traffic network. However, these indexes could not reflect the traffic network topology characteristics like free scale features which are very helpful to protect...
A magnetic field distribution of a inductor core subject to an orthogonal flux is presented. The conventional method is to calculate B and H respectively, assuming that both directions are parallel. Considering the phase difference between B and H under a semi-rotating field, the magnetic tensor permeability is defined and calculated. The new method is necessary in explaining the magnetization behavior...
This paper presents a novel control strategy of power converter used to direct-drive permanent magnet wind power system. The system consists of permanent magnet synchronous generator (PMSG), the generator side converter and the grid side converter. The voltage space vector PWM in field-oriented control is adopted in the control of the generator side converter. Both outer speed loop and inner current...
Singular value (SV)-based image watermarking has recently been gaining attention. The advantage of this watermarking approach is its robustness to distortion attacks. In this paper, we mathematically prove that SV-based watermarking algorithms are robust against distortion attacks as long as the attacks are not severe. The same mathematical proof, however, also confirms that such watermarking schemes...
Compared with the active filters, passive filters are widely used for their cheaper costs, simpler structures and more reliable performance. But conventional passive filters which consist of parameter-fixed capacitors and reactors can not remain good filtering performance in case the system frequency shifts or component parameters change. This thesis compares the advantages and disadvantages of two...
As one kind of multilevel inverters, three-level inverter is widely used in the high-power and high-voltage applications. However, the increasing of the power devices improves the system's fault rate. How to ensure stable operation of the system has become an important research question. Through theoretical analysis and simulation on three-level high-power inverter, the paper analyses the working...
Based on a multi-module-cascaded multilevel inverter structure for the optimization of harmonics, this paper introduces a horizontal phase-shifting sinusoidal pulse width modulation (SPWM) strategy applied to multi-module-cascaded inverter, and at the same time, based on digital signal processor (DSP) and complex programmable logic device (CPLD), this paper also presents a digital algorithm for horizontal...
In this paper, the mathematical model of three-phase four-wire three-level neutral-point-clamped (NPC) voltage source rectifier (VSR) using switching functions is founded and its operating principle analyzed. Then a new nonlinear control law based on Lyapunovpsilas stability theory for the PWM rectifier is presented. With this control law, the converter can be stabilized globally for handling large-signal...
This paper presents a novel fuzzy logic controller (FLC) for indirect vector control induction motor (IM) drive. The fuzzy logic speed controller is used in the speed loop. The 4 kW three-phase squirrel cage IM is fed by a current controlled voltage source inverter (CCVSI). The complete vector control scheme of the IM drive is implemented in real time using TMS320LF2812 digital signal processor. The...
Based on the research on several multilevel basic topologies, this paper presents a general type of multilevel hybrid topology and introduces several selectable degrees of freedom. No matter what change in the hybrid topology it can be resulted in the combination and selection of the degrees of freedom, which expands the topology collection of the multilevel inverter. According to the degrees of freedom,...
The paper introduces the design of fuzzy PID controller based on LonWorks, analyses the hardware composition of the system and the arithmetic methods based on fuzzy control. After simulating with MATLAB, it shows that this method is able to provide good dynamic performance for industrial object with large time-delay which has variant model parameters
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