Abstract—Due to many benefits quasi-Z-source based converters are suitable for renewable energy application, in particular for the photovoltaic systems. However, there are some problems that need closer analysis before quasi-Z-source converter can be fully implemented in PV micro inverters. The goal of this work is to address those problems and achieve stable performance of a micro inverter based on the quasi-Z-source network in the full load profile. The simulation results confirm the feasibility of the suggested solution. Tuning process is revealed.
The present use of micro inverters is mostly restricted to commercial production of electricity to be supplied to the electrical grid. Using these inverters in residential areas is costly because these inverters are costly themselves. Experts in the field of solar energy have estimated that the demand for micro inverters would quadruple by the end of 2017. According to records, every year our nation suffers a huge loss due to shortage of electricity. Although most of the nation has a sufficient supply of electricity, however there are areas which are still deficit of electricity. Some areas have supply for only few hours in the day. Taking into the rural scenario into account a solar inverter was built which gives 220V AC output at a frequency of 50Hz. The DC/DC converter is designed which uses transformer to boost the voltage from 12V DC to 312 V DC . A multilevel boost converter was modeled and designed so as to take an insight on this . Comparisons to other topologies show that the designed controller was the preferred model for the photovoltaic applications. Some of the advantages of multilevel DC – DC converter compared to traditional topologies are low harmonic distortion, low voltage stress, low EMI noise, and High efficiency. A comparison between IGBTs and MOSFETs was made in  and it was found that MOSFET is the preferred device that is to be used for designing the micro inverter. Though the conventional micro inverters are single stage inverters, the two stage inverters show a comparatively higher efficiency and reliability over the single stage inverters . The comparison of the solar panels in PV inverters shows that, the solar panels that are used with micro inverters are capable of yielding a higher power over the others . The micro inverters have a great flexibility over the conventional string or central inverters . Mounting of solar panels in micro inverters is very easy and have the independence of orienting the panels in the desired direction with each panel being oriented in its own direction.
Reduced rated hardware is developed to validate proposed micro inverter. The 50W load is connected in the output side with the grid. IRF560 MOSFET is used as the switch. TLP250 MOSFET driver is used to switch to the MOSFET. Atmega 328 microcontroller is used to develop the switching pulses. Each switching voltage is isolated by separate isolation transformers. The hardware results are shown in above Fig.8: (a) Primary Voltage (b) Capacitor Voltage (c) Current across grid (d) Voltage across grid. The source voltage is transferred to capacitor C1 through inductor L1. When the switch S1 is operated, the source current is stored into capacitor C1. 12V solar panel is used to generate the input power of the microcontroller. The energy storage in the capacitor is shown in Fig.7 (a). The capacitor voltage is equal to 24V. During inverting and non-inverting side of the grid, the capacitor voltage is transferred to the grid through inductor L1 and L2 and voltage match transformer. The value of L1 is 320mH, L2, and L3 are equal to 740mH. The net voltage across the grid side is same as 230V. Harvested solar power is transferred through proposed micro inverter L1, L2, and C2are used to amplify the voltage of the micro inverter
higher conversion efficiency, and tracking efficiency using MPPT. In  a grid connected micro inverter system was analysed. They reviewed past and present conditions of inverters. The same topology used here, was used in this paper, a dc-dc boost half bridge converter connected to the PV system, the Pulse width modulation and MPPT tracking was also carried out at converter level except in this work, the MPPT control algorithm was incorporated at the inverter level for the distributed and centralized applications and the efficiency measured for both converter, inverter and MPPT control functions and compared. In  various inverter topologies and their connection to single phase grid were studied, these topologies were compared, and evaluated against demands, lifetime, component ratings and cost. The research carried out in my work compared two inverter topologies against similar parameters based on a solar radiation model.  analyzed shading effect on PV modules and how it can affect the peak power output by comparing two topologies, and a recommendation made out of the comparison, while the focus of this work was the effect solar radiation values had on the output of centralized and distributed inverter applications. In  a PV array performance model was developed in Sandia National laboratories, which can be used to design (or size) a photovoltaic array for a given application based on expected power and/or energy production on an hourly, monthly or annual basis while this paper used the Liu and Jordan model used in  to obtain the hourly, daily, monthly and annual solar radiation values based on longitudinal positions of a given area. In  the performance of solar PV modules is tested under different irradiance levels. The relationship between the model powers versus its current under different irradiance levels is plotted while this research compares the power output for both inverter applications based on varying solar radiation values.. In  the evaluation of the global solar energy potential at Uturu at latitude 05.33 0 N and
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3. Based on the theory and simulations, experiments on a single-phase photovoltaic micro- inverter have been conducted. The whole system has been divided into two separate parts for experiment— the DC-DC boost converter and DC-AC single-phase inverter. The controllers in both parts are implemented in a high-speed microcontroller TMS320F28035. In the boost converter, an interleaved boost converter topology is adopted, this two-phase topology has the advantages over a single-phase boost converter, such as the reduction of input current ripple and the reduction in power losses. Experimental results are provided to compare a conventional fixed step-size P&O MPPT with a variable step-size P&O MPPT. With the same circuit and conditions, the variable step-size MPPT technique has demonstrated its advantages over the conventional one. Then the experiments have been performed on the DC-AC inverter. One experiment is for a stand-alone inverter, where the OSAP voltage-control strategy is applied. Comparison between a single OSAP controller and an improved OSAP controller is provided, which demonstrates that single OSAP controllers are not suitable for the practical situation, and the improved OSAP controllers can achieve the control goals. Finally, the DC-DC part and DC-AC part are combined together to form the grid-connected inverter system. Experiment results are also given.
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A single-stage novel CCM zeta micro inverter has been proposed for solar PVAC module. Steady-state operation and analysis of the proposed zeta micro inverter in both DCM and CCM have been studied. Micro inverter operation in CCM mode results in reduced conduction losses, switch ratings, and current stress. The traditional CCM mode fly back inverters have closed-loop complexity and stability issues. The proposed inverter provides HF isolation and has only a single switch operating at HF which will reduce the switching losses. The circuit is simple and easy to develop. Critical factors to consider while designing the inverter have been discussed and studied. A 220-W inverter prototype has been developed and tested in the laboratory to validate the claims, proposed operation, and design. The laboratory prototype has a peak efficiency of 93% at rated power of 220 W is connected to BLDC motor and study the characteristics of BLDC motor REFERENCES:
ABSTRACT: This paper focus on a special type of inverter topology for photo voltaic applications. The proposed system is a grid connected inverter system based on interleaved flyback topology. Aim of this paper is to design flyback inverter at high power because today’s PV inverter technology based on this topology only used at very low power as micro inverter. The analysis of proposed flyback inverter and the source of proposed system i.e. photo voltaic array are simulated in MATLAB 2013a software. To track maximum power, the maximum power point tracking (MPPT) method is used and it is modelled using Perturb and Observe (P&O) algorithm. The paper also concerned with the design method as well as operation of flyback inverter with interleaved winding.
The concept of micro inverter has become a future trend for single-phase grid-connected photovoltaic (PV) power systems for its removal of energy yield mismatches among PV modules, possibility of individual PV-module-oriented optimal design, independent maximum power point tracking (MPPT),and “plug and play” concept . In general, a PV micro inverter system is often supplied by a low-voltage solar panel, which requires a high-voltage step-up ratio to produce desired output ac voltage. Hence, a dc–dc converter cascaded by an inverter is the most popular topology, in which a HF transformer is often implemented within the dc–dc conversion stage.
In this paper the grid connected micro inverter using quadrupler is accomplished. The solar energy of the sun is being converted with the help of a quadrupler circuit, DC-AC inverter and some protection schemes. The proposed paper utilises the P&O algorithm to achieve maximum power also some protection schemes such as anti-islanding and abnormal state detection is used. The output of the proposed converter can be connected to grid by synchronising it with the grid. The output of the PV is 24V and its being multiplied by the entire system to get an output of 400V from the system. And the quadrupler used here can reduce the voltage stress across the diodes.
The proposed system is shown in Fig.1 It consists of wind turbine coupled to PMSG which is again connected to two voltage source inverter Generator-VSI and Grid-VSI which is coupled through a DC link. The PMSG is connected through the AC/DC/AC system, the power generated is first transferred to DC link and then from DC link to grid. The system is composed of unbalanced and nonlinear loads at the point of common coupling which distorts the wave form.In addition it inject harmonics into the grid system which is used to compensate harmonics, while fulfilling the reactive power demand. By using the nonlinear and unbalanced loads simultaneously, it enables the grid to supply only sinusoidal current at unity power factor. The system parameters used for simulation study is given in Table -I.
well as to insure its operation as a single aggregated system. Among such interface devices, the most used is the three-phase (or single-phase)PWM VSI, responsible for converting energy available in DC form to AC, as well as to enable the connection of diverse micro sources to the main grid. In grid-connected mode, the objective of the VSI is to control the output power of the inverter in order to follow an established reference (active and reactive power). This is achieved by controlling the output current of the inverter, since the output voltage is maintained by the bulk power system. 
This paper assumes that, at first, the both DGs work as the inverter interface. The losses of inverters and harmonics are negligible; it has showed two different control strategies for the islanded AC micro-grid. The P-f/Q-E droop controller delivers the control real and reactive power and provides frequency and voltage regulation. A decentralized droop control method is proposed with Frequency Restoration Scheme (FRS) to restore the frequency and provide exact real and reactive power. Moreover, the PQ control goal is to adjust the power tracking and to achieve fast dynamic response.
Among the active islanding methods, the active frequency drift method (AFD) has received recent attention . AFD is implemented by adding a short period of zero time into output current of the inverter, as shown Fig.5 The ratio of the zero time Tz , to half of the period of the voltage waveform, Tgrid , is referred to as the “chopping fraction” (cf): The chopping fraction enables the islanding detection to drift up (or down) the frequency of the voltage in the islanding situation. But due to the fixed value of cf, the conventional AFD has a large NDZ and too slow to meet the islanding detection time limit. As a method of overcoming the weaknesses of AFD, a novel AFD scheme, in which pulsation of chopping fraction can deviate the frequency instantly away from nominal, is proposed. This scheme is referred to as AFD with pulsation of chopping fraction (AFDPCF) . It can be modeled as below:
proposed DVSI scheme provides increased reliability, better utilization of micro grid power, reduced dc grid voltage rating, less bandwidth requirement of the main inverter, and reduced filter size. Control algorithms are developed by instantaneous symmetrical component theory (ISCT) to operate DVSI in grid-connected mode, while considering non stiff grid voltage. The extraction of fundamental positive sequence of PCC voltage is done by dq0 transformation. The control strategy is tested with two parallel inverters connected to a three-phase four-wire distribution system. Effectiveness of the proposed control algorithm is validated through detailed simulation and experimental results.
A DVSI scheme is proposed for microgrid structures with superior energy nice. Control algorithms are advanced togenerate reference currents for DVSI the usage of ISCT. The proposed scheme has the functionality to change electricity fromdistributed turbines (dgs) and also to compensate the local unbalanced and nonlinear load. The performance of theproposed scheme has been established thru simulation and experimental studies. In comparison to a unmarried inverterwith multifunctional competencies, a DVSI has many blessings consisting of, improved reliability, decrease value due to thereduction in clear out size, and extra utilization of inverter potential to inject real power from dgs to microgrid. Furthermore,the usage of 3-phase, three twine topology for the main inverter reduces the dc- hyperlink voltage requirement.
The proposed hydropower station does not require water reservoir such as large dams. As a result, this leads to a good environmental surrounding and also permits the utilization of water sources from low head. In order to provide flexibility to adapt to the specific condition of river with low discharge, variable speed turbines seems to be the best alternative. The hydropower station is integrated into the electric power grid to extend the control features and quality of output by reducing certain harmonics. Higher reliability stations with better efficiencies can be attained by replacing mechanical control with power electronics technologies . The detailed modelling of micro-hydro power plant  is illustrated in Fig.2. Permanent magnet synchronous generator (PMSG) is directly coupled to micro hydro turbine of a variable speed and a novel power electronic system (PES) is connected to a load. The proposed PES is composed of a 3-phase rectifier bridge and a 5-level Transistor Clamped Z-Source Multilevel Inverter.
ABSTRACT: This paper presents the simulation and analysis of a PV panel based Micro-inverter for low power. The system consists of two stage of conversion i.e. DC-DC conversion and DC-AC conversion. The DC-DC half bridge push pull converter boosts the input DC voltage into the desired rated input voltage of the H bridge inverter. Moreover different control methods like simple boost control, maximum boost control, and maximum constant third harmonics injection control, methods for inverter is also analyze. The effectiveness of the inverter is examined through simulation. For pure sine wave LC filter has been used.
Abstract: The paper develops a Variable Structure Controller (VSC) to reduce the total harmonic distortion of the output voltage of the micro grid inverter fed from a solar source. It involves the use of a Single Ended Primary Inductor Converter (SEPIC) structure to form the basic inverter module and ensure that the control mechanism regulates the output voltage across a range of operating loads. The theory of VSC arbitrates to imbibe a structural modification to the inverter in an effort to resurrect the trajectory along the load line and accomplish a compliance of delivery of power to the load. The philosophy orients to arrive at a reference for generating the Pulse Width Modulation (PWM) pulses for the switches in order that it serves to increase the fundamental component and lower the higher frequency components of the output voltage. The MATLAB based simulation results improved the ability of the controller to reject servo and regulatory disturbances and offer a better performance over that of the benchmark PI controller. The results obtained from a prototype validate the simulated response and espouse a new dimension to the use of such inverters in the field of renewable energy. Keywords: Micro grid, SEPIC, VSC, THD
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power is the major problem and it needs to be taken care. Also it is not adequate to use fossil fuel as a conventional source for production of electrical power. Hydro power plant is considered to be an environment friendly solution in the countries where rivers are available, for serving rural electrification. Hydro power plants are attracting the power producing industries due to their low administrative and executive costs, possibility of using water for irrigation and drinking purposes, suitability for rural areas and low pollutions for the environment. In this paper an attempt has been made to develop a micro Hydro power plant model that can be used as a battery charger or temporary power supply in case of remote areas. With MATLAB/SIMULINK, the models of the proposed simulation system are all modularized and visualized, and can be reused easily. Solid works has been used to evaluate the mechanical model of the turbine. Alternator was used coupled with the generator to generate the electric supply. This research work finds its application as battery charger or a standby power supply
The aim of this paper is to development of 80KW solar photovoltaic micro source with lithium-ion battery. The proposed system as oppose to the ones reported in the literature, is able to operate in standalone and grid connected mode and seamlessly transition from grid connected to grid disconnected mode of operation. The implementation is based on a standard power electronics cell concept for micro grid applications. Figure shows the connection diagram of the system.