Inverter For Renewable Energy System Research Articles

Modified cascaded multilevel inverter for renewable energy systems with less number of unidirectional switches

Modified cascaded multilevel inverter for renewable energy systems with less number of unidirectional switches

Modelling and design of new multilevel inverter for renewable energy systems with less number of unidirectional switches

This paper presents, a unique topology for multilevel inverter based totally on cascaded connection of fundamental modules. The proposed circuit is able to operate for both symmetrical and asymmetric inverter, which can be used for fuel cell and photovoltaic systems. The magnitude of two dc sources in basic module can be adopted for symmetrical and asymmetrical structure. In the symmetrical multilevel inverter, the magnitude of dc source is identical for each module. However, the magnitude of dc source for basic modules is unequal in asymmetrical configuration and their magnitudes are achieved from binary and trinary progression. Comparison results prove that the proposed circuit requires a fewer number of components, reduced power loss and improve the efficiency of the inverter. Moreover, the total standing voltage on switches is acceptable compare to contemporary topologies. The proposed inverter can be implemented to low-medium power renewable energy systems. Simulation and experimental results for 11, 15 and 19-level inverters are analysed to validate the operation and performance of proposed topology.

Modified cascaded multilevel inverter for renewable energy systems with less number of unidirectional switches

This study presents, a novel topology for multilevel inverter based on series connection of basic modules. The suggested topology is utilize for symmetrical and asymmetric source system, which can be used for fuel cell and photovoltaic systems. In the symmetrical multilevel inverter, the values of input dc are equal. However, the magnitude of dc supplies for basic modules are unequal in asymmetrical multilevel inverter and their magnitudes are achieved from binary and trinary progression. Comparison results prove that the proposed topology needs a less components, reduced power loss and improve the efficiency of the inverter. Moreover, the peak-inverse-voltage on switches is also lower in proposed circuits. A detailed analysis of the suggested circuit is explained through the example of a 11-level, 15-level and 19-level inverter. The performance of the proposed circuit topology is analysed through MATLAB/SIMULINK environment and validated via experiment conducted on a laboratory prototype with real time controller dSpace 1104. The proposed inverter can be implemented for low-medium power in renewable energy systems.

Modified Cascaded Multilevel Inverter for Renewable Energy Systems with Less Number of Unidirectional Switches

Modified Cascaded Multilevel Inverter for Renewable Energy Systems with Less Number of Unidirectional Switches

Simulation of a 3-Level Grid Connected Current Mode Level Shifted SPWM Inverter for Renewable Energy Systems

This article presents the accomplishment of a new current mode PWM inverter using fuel cell stack with single port drive power supply. The proposed inverter circuit requires a single gate drive power supply because all the switching devices are connected on a common source (CS) or common emitter (CE). This common emitter configuration (CE) drastically reduces the number of gate driven power supply to just one without bootstrap technology or using many isolated power supplies. The results of simulation show that the inverter normally operates and produces 3 levels of output inverter current wave-form, and filtered sinusoidal output inverter current is injected into the ac grid. Harmonics in the inverter output current are reduced by using low pass filter.

Improved reliable multilevel inverter for renewable energy systems

<p>New improved multilevel inverter (MLI) topology for Renewable energy systems is proposed in this paper. Cascaded multilevel inverters (CMLI) produce an output voltage level depending on the number of individual sources connected. The main drawback of CMLI is, as the output voltage level increases in number, the switches used in the device also increases and hence the complexity of the circuit increases. As the number of switches increases, the reliability of the circuit decreases. In this paper a novel MLI topology, which employs lesser number of switches, is proposed. A simulation model of CMLI and the proposed MLI has been built in MATLAB/SIMULINK. The reliability of the CMLI and the new topology MLI is analyzed by using MIL-HDBK-217. </p>

Development of Single Stage Thyristor Based Grid Connected Single Phase Inverter for Renewable Energy Systems

Development of Single Stage Thyristor Based Grid Connected Single Phase Inverter for Renewable Energy Systems

Z-source T-type inverter for renewable energy systems with proportional resonant controller

In this study, a novel z-source T-type inverter for grid connected renewable energy system is proposed. The proposed system has ability of boosting voltage level without any additional DC–DC converter or transformer through the z-impedance network. The size of the system is reduced by eliminating DC–DC converter or step-up transformer requirement. Furthermore, an additional improvement in system efficiency is obtained by using T-type inverter structure which is more efficient than the conventional two-level inverter or three-level neutral point clamped inverter. Inverter output currents are controlled by the proportional resonant controller. MATLAB/Simulink simulations show that, fast dynamic response is obtained and steady state error is eliminated. In addition, the inverter output currents are in sinusoidal waveforms and synchronous with the grid frequency and phase. Besides, total harmonic distortion values of the inverter currents are measured as 2.41% which meets the international standards such as IEC61727 and IEEE1547.

Second-Order Sliding Mode Control of a Smart Inverter for Renewable Energy System

In the paper the authors proposes a Second-Order Super-Twisting Integral Sliding Mode Control for a Grid-connected Double-Stage AC-DC/DC-AC Power Converter (DSACPC) of a renewable electrical energy system. The DSACPC consists of a Permanent Magnet Synchronous Generator (PMSG) directly connected to the renewable electric source, a generator-side controlled rectifier and a grid-side inverter. The proposed control strategy applied both to two stages is able to maximize the extracted energy from the renewable source, while to regulate the DC-link voltage and to achieve unity power factor and low distortion currents. The employed control strategy can regulate both the reactive and active power given to the utility grid independently and consents to the system to be enclosed in a smart-grid thanks to its performance. In fact the system giving the desired active power to the grid can be used also as a reactive power compensator in grid balanced conditions or as a system of current harmonic rejection in the case of unbalanced conditions of the grid. For the formulation of the control a sliding-Mode Observer is designed. Simulations and experimental results prove the high efficiency and high performance of the full proposed control system.

A single-phase nine-level inverter for renewable energy systems employing model predictive control

In this paper a single-phase cascaded Multilevel Inverter (MI) consisting of full NPC bridges for renewable energy systems is investigated. The development of the introduced control strategy is based on the application of Model Predictive Control (MPC) technique meeting the required specifications of the individual voltage level regulation of each separate DC source and neutral point potential balance under unity power factor. Illustrating the effectiveness of the developed controller, two separate PV strings are controlled while being subject to transient phenomena related to asymmetric string conditions in terms of solar radiation and reference voltage variation. The inverter topology of full NPC bridges in cascade allows low current THD factor to be achieved using a simple inductor instead of complicated LCL filters benefiting also from low capacitor banks in the DC-link bus. The proposed MPC performance has been validated by experiments carried out on a cascaded MI topology delivering power from two separate PV system strings.

High Performance Inverter For Renewable Energy Systems

This paper makes an analysis of the current demand on inverters for stand-alone renewable energy applications, and shows that reliability, surge power capability and efficiency are the most important aspects to be considered. It is shown that multilevel topologies can be very suitable for these applications due to their inherent high efficiency and robustness. In addition, it is shown that an optimized design must be in agreement with the typical load profile for stand-alone applications. A prototype of 3 kVA was implemented and it has proved itself to be robust. Peak efficiency of 96.0% was achieved: value that is higher than similar high performance inverters currently available in the market.

Three-Phase Low-Frequency Commutation Inverter for Renewable Energy Systems

The connection of distributed power sources with the utility grid generally needs an electronic power converter for processing the locally generated power and injecting current into the system. If the source provides a dc voltage, the converter must be able to produce a low-distortion high-power-factor ac current. The same aspects related with the voltage and current distortion produced by nonlinear loads can be considered for the injection of power into the grid. In the absence of a specific standard, this paper takes as a reference the limits for current harmonics given by international standards. The justification for this approach is that, from the resulting line voltage degradation, there is no difference between injected and absorbed currents. This paper presents a three-phase inverter using low-frequency commutation. An auxiliary circuit is added to the inverter topology to reduce the output voltage distortion, thus improving the current waveform. The main advantages of this approach are the minimization of the switching losses and the elimination of the electromagnetic interference, which avoids high-frequency filters necessary in high-frequency commutation inverters