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Islanding detection is required for both microgrids and individual distributed generations (DGs). Several methods exist in literature but they are with some limitations. In this paper a new scheme is proposed which doesn't fall under any of the existing methods. Cross coupling in control action between the components Id (direct axis component) and Iq (quadrature axis component) is introduced by a...
We present in this work the study and the realization of a photovoltaic system connected to the network. This system was simulated in the Matlab/Simulink environment and a laboratory prototype was manufactured for various tests and measures. Results of MPPT control, PWM control of a DC/AC single-phase converter, signal filtering of harmonic of the inverter as well as synchronization with the network...
We consider the control design of a grid-connected three-phase inverter which is meant to work with a small power generation unit. A two-level (nested) control system is presented. The inner control loop contains repetitive controllers which assure that the output voltage of each phase can track a sinusoidal reference voltage. These voltages are applied to the local loads, which are separated from...
This paper proposes a hybrid seventeen-level induction motor drive with a single DC-link fed from a five-level active front-end converter connected to the utility grid. The five-level active front-end draws power from the grid at unity power factor and feeds a seventeen level induction motor drive. Both the grid side inverter (five-level) and the load side inverter (seventeen-level) are realized by...
Interface between electric grids and renewable energy sources are of a big concern to researchers worldwide. Many efforts are applied to obtain converter topologies and modulation techniques with increasing features regarding switching behavior, input and output distortion, efficiency, switches utilization ratio and reliability. Interfacing constant power sources with sinusoidal systems require huge...
In order to ensure synchronized operation of inverters used in renewable energy systems, the output voltage magnitude, frequency and phase angle must be consistent with that of the power grid when it is in islanding operation. Based on author's previous work on single-phase inverter synchronization control with internal model principle, this paper extends the application of that principle to achieving...
Voltage sag is a major deterrent in efficient power transmission systems. It affects the customers who use single phase power supply. To overcome this problem a Dynamic Sag Compensator was designed and employed, the major difference being the implementation of PV system with PI controller, and additional DC source is provided as a backup instead of PV. This reduces the complexity of the proposed systems...
Grid simulators are used to test the control performance of grid-connected inverters under a wide range of grid disturbance conditions. In the present work, a three-phase back-to-back connected inverter sharing a common dc bus has been programmed as a grid simulator. Three phase balanced disturbance voltages applied to three-phase balanced loads has been considered in the present work. The developed...
Power inverters are essential components of photovoltaic systems and are designed to process the rated power generated by solar plant. Due to variations in solar irradiance, inverters have a current margin, which can be used in reactive power and harmonics compensation. This possibility, known as multifunctional operation, can be interesting in terms of power factor improvement and voltage control...
A device for induction heating of smaller iron components was designed and constructed. The shape of the work coil was matched to horseshoe heating. Required simplicity and robustness of the device excludes the use of water cooled work coil (made of copper tube) which is mainly used in the applications of induction heating. A HF Litz-wire was used in the construction of the work coil in our solution...
The increased trend in using the renewable energy instead of fossil fuel based generation due to its low environmental impact and to facilitate the increased consumption has led to extensive use of distributed generation. The use of power electronics with renewable energy offers wide advantages including greater controllability of generated power and fulfilling the requirements for grid connected...
A 0.65V 2.4GHz/400MHz digital-intensive phase modulator is implemented in 65nm CMOS. In ultra-low voltage design, the two-point modulator suffers a lot from the DCO nonlinearity. In this work, we employ a 2.4GHz semidigital fractional-N PLL with an FIR filter embedded 1-bit high-pass modulation to overcome the nonlinearity problem in the conventional two-point modulator. The 400MHz modulator performs...
Since low voltage ride-through (LVRT) was proposed, its improvements have never been stopped, especially the improvements for operation under unbalanced faults. In this paper, an overall control strategy is proposed to solve the problem that the output current quality and dc-link voltage quality cannot be guaranteed at the same time. For this propose, a current control method is employed to guarantee...
Voltage-controlled inverters are grid-friendly and can cope with the high penetration caused by connecting a lot of distributed generations. In low voltage power systems This paper proposes a simple and precise PQ control strategy based on improved voltage-controlled inverters with inner output impedance. The PLL part is replaced by second order generalized integrator method and it performs well when...
Grid-connected inverter is a key electrical unit for photovoltaic generation system. In this paper, the architecture and its advantages of a single phase photovoltaic grid-connected inverter based on DSP + ARM dual-core control are studied. The novel maximum power point tracking (MPPT) control based on extremum seeking control (ESC) algorithm is used in the proposed system, and the speediness and...
Solar energy today is an important part of our daily lives and the environment around us. Currently, distributed energy schemes can improve industrial systems by installing a DC / AC converter in the new point of load, this is very interesting because it is possible to operate large systems using multiple inverters connected in parallel. This paper presents the approaches existing in the literature...
This paper presents the performance of grid-connected inverter when installed in three-phase four-wire distribution system. The inverter is utilized as power converter to inject power. Furthermore, this inverter is also utilized as a shunt active power filter to compensate current unbalance, load current harmonics, and load reactive power demand. It is controlled such a way therefore it draws or supplies...
The main contribution of this paper is to describe a robust Phase-Locked-Loop approach for three phase generation system with power flow control. This method, which is used to synchronize the inverter and the network voltages, is based on a comparison between the grid and the inverter angular positions, and correction of modulator period. The Solution presented in this paper is applied to the three...
SVPWM is widely applied in the control of the three-phase inverter. The phase angle of the grid takes part in the coordinate transformation and PLL is necessary. However, the non-ideal grid may affect the accuracy of the phase angle. To eliminate the influence of the non-ideal grid, the PLL technology should be improved and it may complicate the control strategy. This paper proposes a novel grid frequency...
Stand-alone micro-grids need a proper management of the active power exchange. This work is focused on the parallel operation of multiple grid-connected converters in an island-grid system. The proposed solution features a master inverter which emulates the grid and multiple grid-connected converters operating in parallel. The current sharing and overload protection is achieved by small frequency...
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