This paper presents a series hybrid wireless charging system with an active adjustable circuitry offering constant current and constant voltage output characteristics. The series hybrid system ...consists of the inductor–capacitor–capacitor (LCC) and series-series (SS) networks are used for improving charging pad misalignment tolerance. An active switch is employed to provide an adjustable CC and CV output for different battery charging stages. To demonstrate the performance of the proposed method, a 310 W prototype was built. A systematic optimization in the parameter of the proposed topology to achieve relative constant output was analyzed within a certain range of the designed operating region. The experimental results indicate that the output current fluctuation is less than 5% with load variations, and the output voltage fluctuation is less than 5% with load varying from 19 to 70 Ω, as the pick-up pads misaligned within 50% of the pad outer diameter.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Large amount of distributed PV generators connected into distribution feeder will cause the out-of-limit of voltage deviation. The calculation models of voltage drop caused by loads and voltage rise ...caused by PV generator are established under different loads or PV distribution along the line, and the maximum PV power injected into the feeder without causing over-voltages is proposed assuming the bus voltage deviation is reaching the upper limit. The maximum PV penetration level of 10 kV typical distribution line is derived under the condition that PV generation is of the same power distribution rule with load, and the voltage margin at the head end of feeder without causing over-voltage is provided. The analysis results show that over-head line can carry more PV power than cable, over-voltage will be avoided by controlling the PV power according to the connection point voltage, and suitably lowering the bus voltage will also allow more PV connecting to the feeder.
To cope with the challenge of more photovoltaic (PV) installation, the impact of the distributed PVs on the short-circuit current in distribution grids is analyzed. It is pointed out that the ...traditional fault location approach based on the fault current is fully adequate in the case that the PVs are installed on the upstream buses. The worst condition in the case of PVs installed on the feeders is given and the adaptability ranges of traditional fault location approach are deduced. Two fault location methods are proposed for the cases of the traditional fault location approach not satisfied, such as, the reclosing based method and the fault direction detection based method. The conclusions are drawn that no more than 1.5 times of the rated current may be seen from the PV whether three phase short-circuit or two-phase short-circuit occur. Almost all of the cable and overhead line based feeders meet the requirements of the traditional fault location approach when the PV installed no more than 25% of the capaci
When the intermittent renewable energies, such as wind generation or PV plant, generate more powers under the condition of the environmental influence, the tidal current of the distribution network ...will change and the voltage at the connected-grid point may exceed the safe limited range. In order to avoid the above phenomenon, it could be done to limit the output energy for these power generation systems. The control methods for the directly-driven permanent magnet (PM) wind generation system are studied, output power curves of the wind turbine are analyzed, control methods of the optimal wind-energy tracking or limiting power operation and end-stage control strategy of the system are designed. This makes wind generation system and PV generation system have the functions of MPPT or limiting power operation, and independent control of grid-connected active power and reactive power. At last, the simulation model of wind generation system is built, and the control strategy is verified by the simulation results.
For the further study about the operation characteristics of distributed resource (DR) connected to the grid, several DR simulation models with different voltage and capacity should be set up to meet ...the requirements of the distribution network. According to the simulation of the distribution network with DR, a method of power conversion for simulation model of DR is presented. In order to meet the requirements of distribution network for the DR with different voltage grade and capacity, the voltage and current of the DR which has standard output voltage and power will be converted to connect to the grid. The simulation model of power conversion is established and applied in the simulation examples of photovoltaic power generation system connected to the grid. Simulation results show that the power conversion method is feasible and effective, and can improve the universality and practicality of the DR simulation model.
When the finite control set model predictive control (FCS-MPC) is applied to the three-level converter, there are problems such as large current harmonics, high requirements for the computing ...efficiency of the microcontroller, complex multi-objective optimization and limited output vector switching. In addition,the mismatch of inductance parameter may directly affect the observation accuracy of FCS-MPC. To solve the above problem,a double vector model predictive control strategy with constant frequency strategy based on the inductance parameters on-line identification is presented.First, a single objective cost function based on the direct power is constructed by optimizing the redundant vector which is selected to balance the neutral-point potential, the design of weighting factor is avoided.At the same time, in order to effectively reduce the grid current ripple under single vector modulation, space vector pulse width modulation (SVPWM) is realized by combining with zero vector control mode. And, a parameter identification method based on model reference adaptive system(MARS) is proposed to overcome the effect of model parameter mismatch.Finally, the results show that the proposed F-MPCCF has good steady-state and dynamic performance from the static, transient and neutral-point potential control.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A digital phase-locked loop (PLL) based on a fictitious two-phase transformation for a grid-connected single-phase power conversion system is described in detail. It is proposed that two voltage ...vectors v alpha , v beta are implemented by a finite impulse response (FIR) filter in this paper. The proposed method is verified by simulation and experiment. In the simulation, besides the steady state response, the influence of the changes of some parameters such as voltage magnitude, grid frequency, the filter order, the 3 rd harmonic injection, on the proposed method is simulated. The fast phase track is realized in the experiment.
This paper proposes an appropriate control systems aiming at the control demands of distributed generation (DG) unit in the micro-grid. When the micro-grid is connected to the main grid, PQ control ...with droop characteristic is adopted for the inverter; When micro-grid separates from the main grid, Vf control with droop characteristic is used. Also, the controller can make the conversion between different modes seamless. The grid-connected mode, islanding mode and transition from grid-connected to an islanding operation are simulation by PSIM software. The simulation results verify that the proposed control strategy is right and feasible.
The energy management system(EMS) is very important for the stable operation of microgrid with multi-micro sources. In this paper, the model of microgrid consisting of micro sources such as PV, ...storage battery and fuel cells is built. In the grid-connected mode and islanding mode, the EMS control strategy is designed and analyzed. Through the EMS corresponding control, each micro sources unit controller performs the transfer between the working manners, the transfer between the control methods, the output of active power and reactive power to ensure microgrid operate stably. Under the various operation conditions, the simulation results verifies the proposed EMS control strategy correctness and feasible.
PDF
