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Cascaded multilevel inverter (MLI) topologies have received an attractive solution for grid connected PV system. In this paper, two-cascaded MLI topologies are presented for grid connected PV system. These are seven level cascaded H-bridge multilevel inverter and three phase cascaded voltage source multilevel inverter. In both presented MLI configurations, each PV module is connected to one DC-DC...
Tow-stage configurations used in photovoltaic (PV) architectures (microinverter, string inverter or multistring inverter), are commonly used because of the advantages in front of mismatch conditions. In case of a partial shading scenario (produced by cloudy days and dust accumulation), two-stage architectures reach higher efficiencies compared with the traditional central inverter. It is because,...
Nowadays, due to the high-scale penetration of photovoltaic systems, reliable and efficient photovoltaic grid-connected systems using the advances of power electronics and advanced control techniques are desirable. In this paper, using the general structure for synchronous dq0 frame, a single-stage three-phase grid-connected photovoltaic inverter with a nonlinear control strategy is developed to generate...
Applying RF circuit design techniques to dc-dc power conversion has pushed the switching frequency of power converters using discrete components beyond 100 MHz. This paper proposes a simple solution to implement synchronous rectification for resonant dc-dc power converters operating in the Very-High-Frequency (VHF) range, by using a symmetric bandpass matching network between the inverter and rectifier...
This paper presents theoretical and experimental discussions on low-voltage-ride-through (LVRT) operation of a modular multilevel single-delta bridge-cell (SDBC) inverter intended for utility-scale photovoltaic (PV) systems. As the penetration of distributed generation from renewable energy sources connected to medium- and high-voltage grids increases, grid-tied inverters progressively need to abide...
This paper focuses on the relevant content of the MVDC-connected photovoltaic system based on the modular cascaded structure. This paper proposes a new topology for the DC grid-connected photovoltaic system with a novel capacitor voltage balancing control strategy, including the module input power ratio feed forward and module capacitor voltage closed-loop control. The proposed control strategy is...
In photovoltaic (PV) systems, module level power electronics has focused a lot of attention in the last years. The microinverter, also known as AC module, has shown to be an interesting solution. For this purpose, PV microinverter architectures with pseudo DC-link consisting in a DC-DC converter followed by an unfolding inverter have been analyzed as good alternatives. This paper proposes a new push-pull...
Grid connected PV systems are the most popular solar electric system on the market today. The most important device in the grid-connected PV system is the inverter. This paper presents a survey on the grid connected PV inverters and the system topologies used for grid connected PV system. The review describes different two level inverter topologies as well as multilevel inverter topologies. Cascaded...
Recently, many high-efficiency buck-boost typed inverters for the photovoltaic (PV) grid-connection applications have been proposed. However, the PV grid-connection inverters are in idle state at nighttime or low insolation. Based on green energy demand, the presented work proposes a high-efficiency bidirectional buck-cascaded buck-boost (BuCBB) inverter. It is developed via the connection of a bidirectional...
This paper proposes an energy storage unit integrated dual input PV system with distributed maximum power point tracking (MPPT). Through applying a symmetrical configuration, the proposed PV system has a single stage structure to implement voltage boosting and inversion, which contributes to the advantages such as compact size and high power conversion efficiency. The design of the control strategy...
This paper proposes a high-efficiency voltage sag protector with low ground leakage current. The line-frequency transformer of the conventional system is replaced by a bidirectional dc-dc converter. A bidirectional dc-ac inverter copes with voltage sag and interruption. It has low ground leakage currents by the common grounded capacitors. A bidirectional dc-dc converter transfers the electrical power...
Microinverters connect a single photovoltaic (PV) module to the grid, and therefore require a high voltage step-up conversion ratio. This is usually achieved in a two-stage approach with a step-up dc-dc converter followed by a step-down inverter. More recently single-stage step-up inverters have been proposed under the assumption that less stages improves efficiency. This paper compares these two...
A grid-connected inverter with energy storage and active DC-link voltage balancer circuit is presented. The system is implemented with two identical 100kW three-phase converters. The operating limits of the system under asymmetric grid currents with the given hardware architecture are considered and solutions for symmetrisation of the DC-link are proposed.
Silicon carbide (SiC) devices are attracting attention as next generation power device because of their high breakdown voltage, low conduction loss, and fast switching speed compared with conventional Silicon (Si) device. SiC power device is expected to be used in electric vehicle and hybrid electric vehicle. The large di/dt and dv/dt in fast switching operation interact with parasitic component in...
In wind generator applications, generator speed varies with wind speed. In the case of permanent magnet synchronous generators, this translates into voltage magnitude and frequency variations. For such applications, it is advantageous to employ active rectifiers with buck-boost capability to interface the generator to a DC-bus. A PWM active rectifier cascaded with a Z-source DC-DC converter circuit...
In this paper, a novel DC-link voltage variation method using a high-efficiency dc-dc converter for the three-phase-inverter of IPMSM(Interior Permanent Magnet Synchronous Motor) is proposed. The proper variation method of DC-link voltage is needed to reduce the torque ripple of IPMSM and, switching loss of the inverter. Also, to meet the high-efficiency requirement of the DC-DC converter with the...
This paper proposes topology of a magnetically coupled residential micro-grid consisting of a multi-port dc-dc converter and a single phase grid-connected bi-directional inverter. It integrates photovoltaic (PV) and fuel cell energies to supply the residential load via a common high-voltage dc bus linked to a single phase bidirectional inverter. A battery is used to store the surplus energy of the...
A novel isolated high step-up gain DC-DC conversion system for HVDC grid-connected PV power generation applications is proposed in this paper. The proposed system has a distributed MPPT and centralized step-up DC-DC configuration. By employing distributed MPPT converter, high power losses caused by partial shading of the PV arrays can be reduced significantly. Modular scheme is adopted for the centralized...
In order to solve the inconsistency of the battery pack in the traditional battery energy storage system, a new type of battery module energy storage system topology and control strategy based on flexible grouping is proposed——Modular Battery Energy Storage System Based on One integrated Primary multi-secondaries transformer. Different from commonly used full-power control mode, the part-power control...
A Z-source boost dc-dc converter along with a multilevel inverter is proposed. In this work, the modified converter with conventional Z-source network has high voltage gain compared to the traditional boost dc-dc converters. It gives a common ground between the dc supply source and load output. The impedance network acts as a bridge connecting the source and the converter. It does not require any...
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