The standalone PVsystem consists of an array of PV panels, powerelectronics converter, MPPT charge controller and a battery backup system . The array of PV panels is used to harness the energy from the sun and it generates electric current . The PV panels are arranged to generate the desired power. The output of the PV panel is fed to the converters. The power electronic converter used is of different topologies. The most commonly used topologies include boost converters, buck-boost converters . These converters increase the reliability of the standalone PV system.The output of the converter is given directly to the load. The excess power can be stored using the battery backup system. The energy from the battery backup system can be used for future purpose. An MPPT charge controller is embedded along with the converter to track the maximum power point . The overall layout of the standalone PVsystem is given in the below figure.
In this paper powerelectronics used in PVpower generation systems have been reviewed and modelled. PV systems need converters for maximum power point tracking, power conditioning, voltage step-up/down as necessary, and for storage charge-controlling. Inverters are needed for AC loads and for utility grid interfacing. The four basic DC-DC converters commonly used with PV systems have been reviewed and modelled. Different DC-AC inverter types and operational archi- tectures have also been reviewed with the two-stage DC-AC inverter, with the point of common coupling (PCC) at the inverter input, suggested as the most cost-effective and efficient architecture for PV-based communal grids. This is because only one inverter is used for the entire system as opposed to an inverter for every module string, resulting in higher efficiencies, low cost, and low harmonic distortions when compared to systems with PCC at AC terminal. The aim of power con- version/inversion is to extract maximum power possible from the PVsystem and where necessary, to invert it at close to 100% as possible. Highlight: 1) DC-DC converters are necessary for power conditioning in PV systems; 2) DC-AC inverters are necessary for AC loads and for utility grid in- terfacing; 3) DC-AC inverters are also used to control the PV systems when grid connected; 4) Best inverter configuration cost-effectively and efficiently allows easy system modifications.
Multi level converters would position them as a prime candidate for the next generation of efficient, robust, and reliable grid connected solar powerelectronics. A modular cascaded H-bridge multilevel inverter topology for single- or three- phase grid-connected PV systems is presented in this paper. The panel mismatch issues are addressed to show the necessity of individual MPPT control, and a control scheme with distributed MPPT control is then proposed. The distributed MPPT control scheme can be applied to both single and three-phase systems. In addition, for the presented three-phase grid- connected PVsystem, if each PV module is operated at its own MPP, PV mismatches may introduce unbalanced power supplied to the three- phase multilevel inverter, leading to unbalanced injected grid current. To balance the three-phase grid current, modulation compensation is also added to the control system. A three-phase modular cascaded multilevel inverter prototype has been built. Each H-bridge is connected to a 185-W solar panel. The modular design will increase the flexibility of the system and reduce the cost as well. Simulation and experimental results are provided to demonstrate the developed control scheme.
Abstract: This paper deals with renewable energy systems in modern smart grids have growth in many countries, and with that increase the quality of power becomes a major concern for powersystem operators, especially at the load side. Among the most important power quality challenges, the harmonics comes on top, as they affect the voltage and current quality at the point of common coupling (PCC), and negatively affects the loads. One of the most used renewable generators is the solar photovoltaic (PV) systems, where it is connected into the low voltage distribution grid using powerelectronics inverters, and with the increased penetration level, massive harmonic current is injected into the network. There is a need to reduced the resulting harmonics distortion and highlight its possible constraints. The simulation is performed with increasing the connected PV modules, and the results are analyzed showing high level of THD with the increased PV penetration at the PCC considering a higher loading level of the distribution transformer.
The main objective of this paper is to model, analyze and simulate an unbalanced distribution system with both complex loads such as induction machine (IM) and renewable such as inverter interfaced PVs. This model can be used in micro grid studies such as power quality, harmonic mitigation or resonance issues. The detailed PV model consists of a single phase synchronizing phase locked loop (PLL), proportional resonance (PR) controller, and maximum power point tracking unit.
A study carried out by Anayochukwu & Nnene (2013) on measuring the environmental impact of power generation at GSM Base station sites, concluded that “it is important to quantify the environmental impact of using DG in GSM base stations. l Greenhouse gases (GHG) pollute the environmentand adversely affect the life of human beings.Indirect impacts generated by GHGs affect the quality of health.. Jade (2011) carried out a study comparing the environmental impacts of DG with hybrid diesel-wind electricity for off-grid communities in Ontario incorporating a Life Cycle Approach. The study evaluation determined that “although designers cannot entirely avoid diesel generated energy, hybrid diesel-wind does have the potential to provide reductions in environmental impacts between 12-46% when comparing it to the diesel generator system. The LCA indicated that the seven First Nations off-grid communities analyzed have the potential to reduce their environmental impacts caused by diesel generated electricity production through the implementation of hybrid- diesel wind” (Jade, 2011). The reduction was determined to be dependent on the renewable energy sources penetration level.
The spread MPPT control of the three-phase cascaded H- bridge inverter is shown in Fig.4.4. In each H-bridge module, a MPPT controller is added to generate the dc- associate voltage reference. Each dc-interface voltage is appeared differently in relation to the contrasting voltage reference, and the total of all missteps is controlled through a total voltage controller that chooses the current reference Idref . The responsive current reference Iqref can be setto zero, or if open power compensation is required, Iqref can similarly be given by a responsive current analyst. The synchronous reference plot phase-catapulted circle (PLL) has been used to find the phase edge of the matrix voltage. As the colossal control scheme in three- phase systems, the matrix currents in abc composes are changed over to dq encourages and oversaw through proportional– imperative (PI) controllers to generate the modulation document in the dq organizes, which is then changed over back to three phases.
Electrical energy storage has an important role to play in improving the performance of electric drive systems in the future. This paper proposes a new topology of powerelectronics and powerelectronics integrated with energy storage system and unit investment. This structure reduces weight and component number compared with the topology of the first, but still allows the use of standard machines. Energy savings and extension system offers full size. Study on the transport system combines year class black city tram, and it seems so obvious that you can achieve energy savings by using energy storage intensively with the proposed structure. The proposed maximum energy available during braking system depends on the kinetic energy and therefore the speed and load of the tram. The actual energy that can be obtained is a function of the more complex, depending on the degree of power and storage system energy, time and function, of course, driving a vehicle during normal braking and speed, and which uses
H-bridge Multilevel Inverter: Multilevel inverters (MLI) are becoming popular than two level inverter in high power applications. Multilevel output is synthesized by small dc voltage levels. In multilevel inverters all the switches are connected in series which allows operation at higher voltage level. The main advantages of MLI are high voltage capability, low switching losses, low dv/dt, less THD, less electromagnetic compatibility. The main three MLI configurations are neutral point converter, flying capacitor and cascaded H-bridge multilevel inverter. CHMI has more advantages than other two mentioned. CHMI does not have flying capacitors and clamping diodes. Main drawback of CHMI is that the number of devices used increases with the number of levels and this increases the gate drive circuits at control stage itself causing high cost and switching losses. To overcome above disadvantages the choice is hybrid multilevel inverter which is derived from cascaded H-bridge inverter. In order to control the MLI output voltage there are several control techniques in the literature. The most efficient methods are based on sinusoidal PWM techniques because it leads to easy control of inverter’s fundamental voltage and as well as eliminates the harmonics. Among various PWM techniques, phase disposition sinusoidal pulse width modulation (PDSPWM) technique is most popular because of its simplicity to apply in CHMI and HMI control with increase in number of levels.
 J. M. Carrasco, L. G. Franquelo, J. T. Bialasiewicz, E. Galvan, R. C. P. Guisado, Ma. A. M. Prats, J. I. Leon, N. Moreno-Alfonso, “Power Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey”, IEEE Trans. on Ind. Electr., Vol. 53, Issue 4, June 2006, pp. 1002 – 1016.  M, A. Green, K. Emery, Y. Hishikawa and W. Warta„ Solar cell efficiency tables (version 37).” Progress in Photovoltaics: Research and Applications, vol. 19, pp. 84-92 (2011)  J. Simon and G. Mosey, “Feasibility Study of Economics and Performance of Solar Photovoltaics at the Sky Park Landfill Site in Eau Claire, Wisconsin”, National Renewable
In the last years global warming and energy policies have become a hot topic on the international agenda. Developed countries are trying to reduce their greenhouse gas emissions. Renewable energy sources are considered as a technological option for generating clean energy. Among them, photovoltaic (PV) system has received a great attention as it appears to be one of the most promising renewable energy sources. Photovoltaic power generation has an important role to play due to the fact that it is a green source. The only emissions associated with PVpower generation are those from the production of its components.
Recently researchers have used power converters to imple- ment power management or EMS for ac and dc microgrids. Re- sults in the literature include power quality solutions , stabil- ity issues , high frequency microgrids , dc microgrids , , renewable generation interface –, optimized third- level microgrid control (as described in ) with load and gener- ation forecast , . Most publications have focused on the energy management of microgrids including several distributed resources (DR) , –, while in this paper, we focus on managing a powersystem that includes battery storage. Fur- thermore, many referenced publications deal with three-phase systems, while this paper focuses on a single-phase-inverter- based EMS. Carnieletto et al. in 2011 , and more recently, Wai et al.  and de la Fuente et al.  have presented single- phase inverters for grid interface in both grid connected and stand-alone mode of operation. This paper, while following along the same line of research, introduces the prospective of continuous service to critical loads with peak power shaving. It also includes a simple economic analysis to demonstrate the ad- vantages of the peak power shaving method. While applications that emphasize energy security have been considered by Arnedo et al. in  and , the combination of energy security and energy cost reduction combined is new to these authors’ knowl- edge. Furthermore, this paper presents simpler control systems and different topologies than those reported in  through . Another innovative feature of the EMS presented in this paper is the use of a single off-the-shelf three-leg integrated power module to accomplish all the required tasks including battery charging, peak shaving, and fault tolerance.
Integrating the Solar PV and Wind Energy Systems with the conventional grid has proved to be a great boon to the power industry. In this paper, we shall study about the Solar PV integration, a comparison between the efficiency of Solar PV systems and Wind Energy Systems, the impacts of Solar PV integration with the conventional grid and about the methods to mitigate the problems arising from the increased Solar PV integration (penetration) in the conventional grid. Two or more different system use for making energy called hybrid system. In this paper hybrid system is a combination of wind energy and solar PV array with showing hybrid system is more important than individual one. The proposed DC-DC boost converters are used for both sources i.e. wind and PV having less number of switches. Using PI controller, varying DC output are converted into constant. Hybrid system not only improves the power but also cost of the system. This paper proposed that the power quality improvement of hybrid system using D-STATCOM use in the system. To remove the harmonics in the current and give constant power supply. This proposed hybrid system simulates on MATLAB software.
The traditional method of assessing the power generator performance is by es- timating the ratio of system output (electricity) during a period of time (such as; daily, monthly, or yearly) to the generator maximum capacity for the same pe- riod of time. Although this type of assessment method is applicable to the dif- ferent types of power generator such as: oil, gas, coal, renewable … etc., solar power generators require some other considerations. The intermittent solar ir- radiation, and other weather conditions affect significantly the long term per- formance of PVpower generators. The six major performance measures found in the literature can be summarized as follows:
ABSTRACT: Consumer electronics, domestic appliances and a large range of industrial applications, namely powerelectronics based, can cause high disturbances in the supplied electricity. Normally soft starts are used for avoiding this problem and to achieve smooth starting of large capacity induction motors. A 3- phase AC voltage controller is employed as a soft-start. But, this takes harmonic-rich current especially while operating at large firing angles. In this paper, the effect of inserting a shunt active filter to provide harmonic and reactive power compensation in a soft-start has been studied. The shunt active filter has been inserted between the AC voltage controller and power supply to take care of the reactive power requirement of the motor and AC voltage controller and also to provide harmonic compensation. Therefore, as a result of theses harmonics, a traditional passive filters are used to suppressed the integer multiple fundamental frequencies, but due to the passive filter draws back in producing series or parallel impedance with the supply impedance and heavy in sized, its limitations in service becomes an old scheme. The application of shunt active power filter in mitigating these harmonics problems supersedes the used of passive filter.
This study presents an optimization procedure to design solar off-grid PV systems for a residential unit to find the effective way to use solar energy at the lowest cost possible. The proposed system may provide highly efficient, and clean solar powered electricity that can meet the daily load demands of the residential unit. Sizing of the off-grid PV systems based on the specific residential load requirement is also done. The area selected is a typical residential unit located in the campus of mechanical engineering department at Diyala University. The simulation is performed using the MATLAB software to validate the design results.
In order to address the above limitations, partially isolated multi-port topologies  -  are becoming increasingly attractive. In these topologies, some power ports share a common ground and these power ports are isolated from the remaining, for matching port voltage levels. A tri-modal half-bridge topology is proposed by Al-Atrash et al. in and . This topology is essentially a modified version of the half-bridge topology with a free-wheeling circuit branch consisting of a diode and a switch across the primary winding of the transformer. The magnetizing inductance of the transformer is used to store energy, and to interface the sources/storage devices. Wuhua Li et.al.  - , have proposed a decoupled controlled tri-port dc-dc converter for multiple energy interface. The power density is improved and circuit structure is simplified. However, it can interface only one renewable source and energy storage element. Further, the pulse width modulation plus phase-shift control strategy is introduced to provide two control freedoms and achieve the decoupled voltage regulation within a certain operating range.
Large penetration of the DG to the grid affects the reliability and power quality of the system. There is also risk of control and stability of the system. When circuit breaker in a distribution system opens Islanding of DG could occurred. If Due to insufficient fault current the loss-of- mains is not detected the DG will continue to operate. The islanded system could continue to operate when the DG unit is able to match active and reactive power load demand precisely. On the other hand it is very unrealistic that DG will exactly meet the load demand in the system when the circuit breaker opens. Due to this when DG unit tries to supply the load large frequency and voltage variations will occur. So, loss ofmains detection system is mandatory for interconnection, which automatically disconnects the DG unit in case of a loss of mains and the unit remains disconnect till the grid is restored .
Figure 2 shows the diagram of the proposed low power solar PVsystem. Low power solar PVsystem in- tends to operate independently off the conventional elec- tric system. PV module produce continuous DC electrical energy during the daylight hours, hence, batteries are necessary to store the continuous DC electric energy from the PV module. In this process, charge controller device is necessary to avoid the voltage variation during the energy storing process. Furthermore, charge control- ler will prevent the battery over-charging and damage the PV module. There are two combinations for the low power solar PVsystem, DC system and AC system. For DC system, the DC electric energy that is stored into the battery storage is utilized directly without any complica- tion and all the DC appliances are directly connected to the battery storage. AC system uses the PV inverter to convert the DC electrical energy from the battery storage to AC power for AC appliances.
Abstract- In addition, DC micro grids diverted the attention of researchers and powerelectronics industry in recent years to stimulate renewable energy technologies (RETs) and distributed energy resources (DERs) deployment and encouraging technological innovation to reduce green house gas (GHG) emission and achieve energy security and independence to meet the growing electricity demand. So for many studies have been done on successful integration of RETs and DERs, operation and control, protection and stability issues, simultaneously and satisfactorily implemented during feasible operation of microgrid. Studies show that DC transmittable power can increase the system efficiency up as compared to AC. But still DC bus voltage fluctuation, power quality and flow during the transition between grid connected mode to islanded mode or transient load insertion which intend to DC microgrid instability are the problems which need to be investigated and resolved for the effective use of DC microgrid generation. Continuously increasing demand of Microgrid with high penetration of distributed energy generators, specially focused on renewable energy sources is modifying the traditional structure of the electric distribution grid. In this concept DC microgrid voltage, power flow, power quality and energy management different controls and techniques are reviewed. This concept can be extended as Induction Motor drive Power management for DC Microgrid Application.