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In order to test the renewable energy grid-connect converters, a grid simulator is in need which is able to simulate grid transition such as voltage sags, unbalanced voltages, flicker and low-order harmonics. The main concern of this paper is on the harmonics generation. A compound control strategy is proposed on the basis of three-phase inverter to generate precise controllable required voltage harmonics...
High frequency is an effective method to improve transmission efficiency of inductively coupled power transfer (ICPT) system. However, it is hard for the high capacity semiconductor device to meet the high frequency need. In this paper, a novel multiple-frequency inductively power transfer system is proposed. By adopting a novel multiple-frequency topology of inverter, the transfer frequency of the...
In this work, three-phase single stage grid-connected photovoltaic system using current control inverter is simulated using Matlab/Simulink. To deal with varying irradiance conditions, the incremental conductance MPPT has been used, however in order to improve the power quality a three-level (NPC) inverter based SVM control together with LCL filter has been used. The main result of the project is...
For the harmonic resonance problem of the photovoltaic multi-inverter parallel grid-connected system, this paper mainly analyzes the resonant characteristics of the LCL interface circuit. The model of the LCL interface circuit is given, and with the increase of grid-connected inverter number, the resonant characteristics are analyzed respectively which the circuit system is stimulated by the harmonic...
This paper is introducing a new method of operation for a series resonant converter, with intended application in megawatt high voltage DC wind turbines. Compared to a frequency-controlled series resonant converter operated in sub-resonant mode, the new method (entitled pulse removal technique) allows the transformer design to be determined by peak load and maximum switching frequency, while still...
A strategy for voltage harmonics suppression is proposed to upgrade existing grid-connected inverters. It utilizes the already available measurement of the voltage at the point of common connection and the inverter output current. As a result, on top of conventional power injection, the inverter is equipped with an additional feature for harmonics compensation. Model analysis, simulation and experiments...
This paper presents a concept for a compact high voltage generator based on a highly integrated power chain switching at frequencies above 500 kHz. The high frequency operation in combination with the high integration approach enable a reduction of volume and weight of HY-generators used in industrial or medical applications.
The problems associated with the harmonics needs more attention as more number of distributed generators like PV and wind are integrated into a distribution system. Although the integration presents a lot of benefits, satisfying the needs of local load requirements by reducing the line losses and facilitating congestion management, the problems of power quality that impact the distribution system...
This paper presents the filter setting for expand the operation range of IPMSMs in overmodulation region of inverter. To operate IPMSMs in the overmodulation region, it is necessary to deal with harmonics components. In this paper BSF is utilized to suppress the harmonic components, and its setting method is mentioned. The operation range in the overmodulation region is expanded appropriately by setting...
This paper introduces a closed loop control WPT system with LCL-LC resonance structure. The characters and advantages of this structure is analyzed. In the unstable environment such as changing bar voltage and lateral displacement, this system ensures constant current output to battery load with an efficiency above 80%, which is verified through practical measurements in this paper.
For a wireless power transfer system, when the transmission distance is long, the power is low in the case of low coupling coefficient. In order to solve this problem, a new compensate topology of primary side based on parallel T-type structure is proposed. The circuit structure and impedance characteristics of the system are analyzed, the compensation circuit can be used to make the primary side...
Power Quality is an essential aspect for reliable operation of power grid, including inverter based wind power generation. This paper focuses on real time problem harmonic injection and resonance in power network for 5MW Wind Power Plant. The Wind Plant includes 10 inverters, each of 500KW and connected to 33KV bus. Wind Power is evacuated at 220 KV Substation via 4 km Cable of 33 KV. At certain wind...
This paper proposes a novel control strategy for the smooth transition between grid-attached and islanded mode of microgrid. The proposed control strategy is based on a proportional resonant current controller to regulate inverter current, without requiring any islanding detection algorithm or switching between different controllers. Equal power sharing is achieved as well by droop control using reference...
A grid-connected inverter is equipped with an LCL filter after its output. This filter has a resonant characteristic and many active damping methods have been researched to suppress the resonant effects. The inverter is often controlled digitally and there is a control time delay which is inevitable due to A/D conversion, computation times, and so on. This delay degrades stabilities and damping effects...
Direct phase or indirect frequency control methods are used in series-resonant bridge power inverters for induction heating to maintain maximum power transfer as the load equivalent electrical parameters change during the heating process. In these applications, to control the power level it is common to use the above resonance operating frequency, where only measurement of the deviation of the phase...
Synchronous reference frame Phase-locked loops (PLL) are widely used in three-phase DG (Distributed Generation) systems, and the PLL behaviors always affected by the grid and local load. When DG is at the grid-connected condition, the output of PLL always stays at power frequency, while islanding occurs, the output of PLL would jump to the resonant frequency of local load. However, we cannot identify...
The photovoltaic grid-connected power system filter interface circuit analysis and optimization design is the important measure to improve the system stability and grid power quality. This paper analyzes the three-phase LCL filter interface circuit model respectively on ABC coordinates and αβ coordinates. The frequency characteristic of L, LC, LCL three kinds of filter carries out comparative analysis...
For an inverter drive induction motor control system, a typical problem encountered is the nonlinear voltage gain caused by the non ideal characteristics of the power inverter. The switch dead time will introduce waveform distortion and fundamental voltage drop to the system. If not compensated, such distortions will introduce harmonic components which will cause additional loss in the induction machine...
In this paper, the performance characteristics of two coil and three coil structure for Wireless Power Transfer(WPT) systems are compared. The circuit model of both the systems are derived with the help of circuit theory. To obtain the high energy efficiency, the three coil structure is proposed. The analysis shows that this structure provides high efficiency for wider range of loads. The Simulation...
The article presents the review of power electronics converters applied in induction heating. The IH application area of the medium frequency and medium power was taken into account. The different types of power electronics converters, resonant circuits and numerous control methods are introduced. The issue of inverter output and heating inductor matching is presented, including examples of solutions...
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