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International Journal of Engineering, Applied and Management Sciences Paradigms (IJEAM)

Volume 54 Issue 3 June 2019 394 ISSN 2320-6608

Design and Implementation of Non-Isolated

Bidirectional DC-DC Converter in Hybrid

Energy System

Varnika Kulhari1, Sunita Kumari

2, Sudhir Y Kumar

3

1,2,3School of Engineering and Technology

Mody University of Science and Technology, Lakshmangarh, Sikar, Rajasthan, India

Abstract- Due to exploitation of conventional energy sources reliable and innovative methods of generating electricity are

required. The imperfections of conventional methods can be modified by using a system that is Hybrid with renewable

energy sources. The piece of work for designing such system is done by using a bidirectional converter for energy storage.

A new stand-alone wind–PV hybrid generation system is proposed for DC and AC loads. For the PV power generation

branch, a converter is adopted to harness the maximum solar power by tuning the duty cycle. MPPT technique is

implemented in the solar generation unit to obtain better efficiency. In the installation of power plant, MATLAB

simulation studies finds applications in selecting the system and to choose particular components for the Solar PV and

wind turbine applications. As a result of the SIMULINK model for the components of the Hybrid Energy System desired

characteristics are obtained.

Keywords – Hybrid Energy System, Power Generation, Bidirectional DC-DC converters, PMSG, Photovoltaics

I. INTRODUCTION

Today, the generation of electricity is shifting towards renewable energy sources. As, recent developments and

trends in the electric power consumption indicate an increasing use of renewable energy. Virtually all regions of the

world have renewable resources of one type or another. By this point of view studies on renewable energies focuses

more and more attention. Solar energy and wind energy are the two renewable energy sources most common in use.

Wind energy has become the least expensive renewable energy technology in existence and has raised the interest of

scientists and educators over the world. Photovoltaic cells convert the energy from sunlight into DC electricity. PVs

offer added advantages over other renewable energy sources in that they give off no noise and require practically no

maintenance. Many studies have been carried out on the use of renewable energy sources for power generation. The

wind and solar energy systems are highly unreliable due to their unpredictable nature. Earlier, a PV panel was

incorporated with a diesel electric power system to analyze the reduction in the fuel consumed. It was seen that the

incorporation of an additional renewable source can further reduce the fuel consumption. When a source is

unavailable or insufficient in meeting the load demands, the other energy source can compensate for the difference.

Also for increasing the efficiency of system and to improve power quality of the current obtained modifications can

be done in the converter used in the system. Environmentally friendly solutions are becoming more prominent than

ever as a result of concern regarding the state of our deteriorating planet. Hybrid renewable energy systems (HRES)

are becoming popular as stand-alone power systems for providing electricity in remote areas due to advances

in renewable energy technologies and subsequent rise in prices of petroleum products. A hybrid energy system,

or hybrid power, usually consists of two or more renewable energy sources used together to provide increased

system efficiency as well as greater balance in energy supply. An example of a hybrid energy system is

a photovoltaic array coupled with a wind turbine. Hybridizing solar and wind power sources provide a realistic form

of power generation. This would create more output from the wind turbine during the winter, whereas during the

summer, the solar panels would produce their peak output. Hybrid energy systems often yield greater economic and

environmental returns than wind, solar, geothermal or stand-alone systems by themselves. Most of us already know

how a solar/wind/biomass power generating system works, all these generating systems have some or the other

drawbacks, like Solar panels are too costly and the production cost of power by using them is generally higher than

the conventional process, it is not available in the night or cloudy days. Similarly Wind turbines can’t operate in

high or low wind speeds and Biomass plants collapse at low temperatures. So if all the three are combined into one

hybrid power generating system the drawbacks can be avoided partially/completely, depending on the control units.

As the one or more drawbacks can be overcome by the other, as in northern hemisphere it is generally seen that in

windy days the solar power is limited and vice versa and in summer and rainy season the biomass plant can operate

in a full flagged so the power generation can be maintained in the above stated condition. The cost of solar panel can

be subsided by using glass lenses, mirrors to heat up a fluid that can rotate the common turbine used by wind and

other sources. Now the question arises what about the winter nights or cloudy winter days with very low wind



speeds. Here comes the activity of the Hydrogen. As we know the process of electrolysis can produce hydrogen by

breaking water into hydrogen and oxygen, it can be stored; hydrogen is also a good fuel and burns with oxygen to

give water. Hydrogen can be used to maintain the temperature of the biomass reservoir in winter so that it can

produce biogas in optimum amount for the power generation. As stated above biogas is a good source in summer; in

this period the solar energy available is also at its peak, so if the demand and supply is properly checked and

calculated the excess energy can be used in the production of hydrogen and can be stored. In sunny, windy &hot

day, the turbine operates with full speed as the supply is very high, and this excess power can be consumed for the

process of manufacturing hydrogen. In winter, the power consumption is also low so the supply limit is low, and

obtained with lesser consumption [1]. The rest of the paper is organized as follows. Proposed System is explained in

section II. Simulation and results are presented in section III. Applications and advantages are provided in section

IV. Concluding remarks are given in section V.

II. PROPOSED SYSTEM

The Aim of this paper is to implement the converter and inverter for the wind and solar hybrid system and to

advance hybrid energy system in field of electricity generation. For the hybrid system, extracting energy from wind

and solar as possible and feeding the load with high quality electricity are the two main targets. This strategy makes

hybrid system work properly when a voltage disturbance occurs in distribution system, and it stays connected to the

main grid. This project presents the notion of utilizing both photovoltaic and wind energy sources simultaneously for

electricity generation and the operation of the system sustains this notion. The inherent nature of DC DC converter is

used to obtain DC output and additional input filters to filter out high frequency harmonics. This report presents the

design and implementation of power converters for wind conversion systems. The term bidirectional means that it

allows the flow of power in both directions depending upon the demand and capacity. This bidirectional behavior of

power flow is achieved using a bidirectional buck boost converter which allows DC voltage flow across it to the

energy storing unit when it is discharged and reverse the direction of power flow when there is no power obtained

from the renewable energy sources and battery is fully charged. The harmonics arise while implementing are also

rectified using filter circuit for the most part using this method.

As electricity deficiency is a major problem of world, so the system is made more flexible through using solar

energy and wind energy which is a renewable form of energy. So, for power solar panels are used. In this project we

use solar energy and wind energy which is used to generate electricity and also store that energy in the battery.

A hybrid energy system is wherever one amongst the inputs is connected to the output of the PV array and the other

input connected to the output of a generator. The wind generator and solar array are the main power sources of the

system, and the battery is used for energy storage and power compensation to recover the natural irregularity of the

wind power and solar irradiance. The proposed system consists of a DC/DC boost converter, a bi-directional DC/DC

converter. This report presents a new bidirectional dc-dc converter for a hybrid wind or photo voltaic energy system.

The configuration allows the two sources to supply the load separately or simultaneously, depending on the

availability of energy sources. The features of the proposed design are separate ripple free input current, low

switching loss, better input output characteristics, more efficient, individual and simultaneous operation is

supported. MPPT can be realized for each source. The power converter can not only transfer the power from a wind

generator, but also improve the stability and safety of the system. The inherent nature of converter, additional input

filters are not necessary to filter out high frequency harmonic content is determinant for the generator life span,

heating issue and efficiency. The fused multi-input rectifier stage also allows maximum power from the wind and

sun. When it is available an adaptive MPPT algorithm will be used for photo voltaic (PV) system. The topology uses

a bidirectional converter. This configuration allows the two sources to supply the load separately or simultaneously

depending on the availability of the energy sources. Simulation is carried out in MATLAB/ SIMULINK software

and the results of the bi directional converter and the output from the renewable sources are presented.

The block diagram of system consists of the controller, converter, battery and the power supply. The controller is the

one which monitors the entire system.

Solar power is the alteration of energy from sunlight into electricity, either directly by means of photovoltaics (PV),

or indirectly by means of intense solar power. Solar energy is most abundant source of energy in world. Photovoltaic

is an effective approach for using solar energy. Photovoltaic systems have long been used in specialized

applications. After hydro and wind powers, PV is the third renewable energy source in terms of global capacity.

Photovoltaic systems are best known as a method for generating electric power by using solar cells to convert

energy from the sun into a flow of electrons by the photovoltaic effect. Solar cells produce direct current electricity

from sunlight which can be used to power equipment or to recharge a battery. Photovoltaic power capacity is

measured as maximum power output under standardized test conditions (STC). But the output from these systems

will be low. A tracking system must be reliable and able to follow the sun and wind with a certain degree of



accuracy MPPT methods can be implemented in order to track maximum power and thus solar and wind energy can

be utilized in an efficient manner.

When sun shines the radiations are collected by the solar panels. These panels are designed with solar cells

composed of semiconductor materials. The main function of Solar panels is to convert solar energy into DC

electrical energy generally of 12V, which is further used for the rest of the circuit. The number of cells required and

their size depends on the rating of the load. The collection of solar cells can produce maximum electricity. But, the

solar panel must place exactly at right angles to the sun rays. Extracting electricity form solar energy and using that

energy to dive motor and storing that energy for less insolation period plays vital role in the working of the project.

For any solar based system, the capacity to drive water is a function of three variables such as power, flow and

pressure. The energy collected by the panel runs water pumping process is a sensible way of solar electric power

utilization throughout the sunshine hours. Solar arrays can provide specific amount of electricity under certain

conditions.

In order to determine array performance, following factors to be considered:

characterization of solar cell electrical performance

degradation factors related to array design assembly, conversion of environmental considerations into solar

cell operating temperatures

Array power output capability.

The following performance criteria determine the amount of PV output.

Power Output Power output is represented in watts and it is the power available at the charge

controller/regulator specified either as peak power or average power produced during one day.

Energy Output Energy Output indicates the amount of energy produced during a certain period of time and

it is represented in Wh/m2.

Conversion Efficiency It is defined as energy output from array to the energy input from sun. It is also

referred as power efficiency and it is equal to power output from array to the power input from sun. Power

is typically given in units of watts (W), and energy is typical in units of watt-hours (Wh).

Wind power, the natural source of energy. Wind flows from high pressure to low pressure. This is due to solar

radiation falling on the earth surface. The flow of wind having kinetic energy it is due to the virtue of its motion.

Wind power is available more at the coastal areas during day and night, whereas solar energy is available only

during the daytime. Power generation is done only in this half of the day. Next half of the day (i.e., nighttime) the

unit has to be off mode. To overcome this difficulty wind generation is integrated with the solar power generation.

Wind turbine will extract the kinetic energy from the wind and converts to mechanical power which helps to rotate

the Electric power generator. Fig.4.2 shows the wind energy conversion principle. Energy conversion takes place

from wind energy to electrical energy. Wind turbine, electric generator plays a key role in this conversion. The

amount of converted energy depends on the wind energy available at that place. The classical equation of wind

power can be explained below. Wind power can be computed by the kinetics which relates the objects in motion.

We can extract the wind power up to its cut in speed 3m/s. Research is going on to decrease the cut in speed, so

from the little bit of wind flow, it is possible to extract the power.

Solar-Wind Hybrid Energy System uses the battery for storage of energy. Storage elements improve the system

reliability. The rating of the battery depends on our load. All the DC power operated devices are connected to this

battery directly.

The battery installed in the system is the Li ion battery. The term ―lithium-ion‖ refers not to a single electrochemical

couple but to a wide array of different chemistries, all of which are characterized by the transfer of lithium ions

between the electrodes during the charge and discharge reactions. Li-ion cells do not contain metallic lithium; rather,

the ions are inserted into the structure of other materials, such as lithiated metal oxides or phosphates in the

positive electrode (cathode) and carbon (typically graphite) or lithium titanate in the negative (anode). Operational

analysis of the proposed system determines that renewable energy technologies offers clean, abundant energy

gathered from self-renewing resources such as the sun, wind etc. As the power demand increases, power failure also

increases. So, renewable energy sources can be used to provide constant loads. A new converter topology for hybrid

wind/photovoltaic energy system is proposed. Hybridizing solar and wind power sources provide a realistic form of

power generation.

2.1 Working Principle:

The basic working principle of the system is easy to understand. The system is divided into smaller circuitries. First

one is solar circuit; it provides DC power to the components when power is needed by them. This includes a solar

panel in which solar cells are connected in series and parallel to construct solar array. Temperature and irradiance



values are mentioned by the user to the PV module inside the PV cell. The outputs of the current and voltage are

measured using voltage and current measuring devices. The product of these outputs is fed to the scope to obtain the

power curve for the circuit. The obtained waveform is then passed through a filter circuit which is made up of

inductor and capacitor. The main objective of filter circuit is to reduce the harmonics and obtain ripple free

waveform. Further, output from the filter is given to the battery via charge circuitry which is controlled by

controller.

Second circuit is for the power generation using wind turbine. In this case output from the wind turbine which is AC

and is fluctuating with high amount of harmonics is fed to rectifier. Rectifier is a power converter that converts AC

into DC quantity which is required for bidirectional dc-dc converter. But, this DC output will have harmonics and

THD (total harmonic distortion) ratio will be high for such waveforms so we will pass it through filter circuit. The

obtained DC from the filter circuit is now ready for its connection in Bidirectional dc-dc converter along with solar

panel output.

Third circuit is for bidirectional dc-dc converter composed of both buck and boost type of converters. The constant

current source is connected to the one end of the converter which denotes the incoming current from the grid. On the

other side battery is connected to store the energy. The proposed model of bidirectional converter is made of two

switches, two capacitors, and one inductor. Controller is connected to both the switches and the buck and boost

operation will be chosen according to the switch which is open or close. The inductor at the output end of the system

is utilized for the reconfiguration of the diodes. The operation of the system can be defined as the biasing of the

switches takes place .When the first switch is forward biased the input source to which the diode is configured will

get enhanced to the converter, then the system becomes buck converter. When the second switch is forward biased

the first diode will get reversed biased thus turning off the operation of the system as boost converter and starts to

operate. The relation of input- output can be witnessed using scope. If the voltage measured is higher than the

reference voltage, then the bidirectional should send some current to the battery (i.e. buck converter), if voltage

measured is lower than reference voltage then bidirectional should send current to boost converter. Boosting the DC

voltage to enough level using the converter and obtaining pure AC voltage from the inverter are the keys to realize

the above targets.

III. SIMULATION

The basic idea of simulating a bidirectional converter is to store the maximum amount of energy harnessed from the

power sources. Since, these converters have capability of bidirectional power and current flow so they can supply

energy to load when demand is high and also, these can absorb energy when demand is lower than the production.

Simulation of a Bidirectional dc-dc converter is done using MATLAB SIMULINK in this chapter. A three switch

(MOSFET) converter along with three capacitors and two inductors is designed for DC-DC conversion. This

converter is non – isolated (transformer less) in nature i.e., there is no isolation between the input and output port of

the converter. This converter functions in two operating modes. Simulation and result analysis of both modes are

done in following sections.

3.1 Forward Operation Mode of Bidirectional DC-DC Converter

In forward operation mode (A to B operation) voltage from battery is fed into converter and then it is stepped up

(Boost operation) for the DC bus. In this case the nominal voltage of battery is 85 volts. Results are obtained in form

of voltage waveforms for the same using scope block in SIMULINK.

3.1.1 Schematic diagram of converter in forward operation using SIMULINK

The schematic diagram of Bidirectional dc-dc converter designed in MATLAB is shown in Fig 5.1 and is composed

of Lithium ion battery, inductors, capacitors. MOSFETs, scope, and current/voltage measuring devices.



Figure.1. Forward operation of Bidirectional dc-dc converter

3.1.2 Output Waveforms of Forward Operation Mode

In this operation two switches G2 and G3 are in conduction mode (controlled) while G1 is in OFF state. The voltage

is stepped up in this case with wide conversion ratio (1:4). The duty cycle of forward operation mode is taken as 0.7.

Fig.5.2 and Fig.5.3 shows the resultant voltage and current waveforms respectively. Resultant waveforms show the

step up operation of the converter.

Figure.2. Voltage waveform for forward operation

Figure.3. Current waveform for forward operation

3.2 Reverse Operation Mode of Bidirectional DC-DC Converter:

In reverse operation mode (B to A operation) voltage from load is absorbed by battery and is stepped down (Buck

operation). In this case the nominal voltage of battery is 85 volts. So the higher voltage level of DC link is stepped

down to the nominal voltage and is stored inside the battery for later usage. Results are obtained in form of voltage

waveforms for the same using scope block in SIMULINK.

3.2.1 Schematic diagram of converter in reverse operation using SIMULINK

The schematic diagram of Bidirectional dc-dc converter designed in MATLAB is shown in Fig 5.4 which is similar

to that of diagram of forward operation mode. The only difference is the conducting and OFF state switches. In this

case switches G2 and G3 are in OFF state while switch G1 is controlled.



Figure.4. Reverse operation of Bidirectional dc-dc converter

3.2.2 Output Waveforms of Reverse Operation Mode

The voltage is stepped down in this case with wide conversion ratio (4:1). The duty cycle of forward operation mode

is taken as 0.4. Fig.5.5 shows the resultant voltage waveform of the reverse operation. The resultant voltage is 65

volts (approx) according to the waveform obtained.

Figure.5. Voltage waveform of reverse operation of BDC

According to the results obtained after the above simulation this bidirectional converter is then implemented in a

Hybrid Energy System in next chapter. As we ccan see the major advantage of this converter is better efficiency and

energy storage when demand is lower than production. The basic idea of developing this system is to obtain

maximum power from sunlight and wind speed. The solar panel generates 12V of voltage that can be converted to

higher levels by integrating them into series combinations. DC output is obtained from solar power source while AC

is obtained from wind energy source. These are fed to the essential converters so that they can be converted into

desired output at load terminal. Harmonic content in the power obtained from these sources can be filtered by using

capacitor filter circuit.

3.3 General Architecture of Hybrid Energy System for DC Load

Hybrid energy system (Wind and Solar) is designed in SIMULINK. Fig.6.1 shows the general architecture of the

simulated hybrid energy system. It comprises of four sub-systems which are solar power generating unit, Wind

power generating unit, Energy storage unit and DC Load connection.



Figure.6. General architecture of Hybrid Energy System for DC Load

3.4 Designing of Solar Power based generating unit

Solar power based generation unit is designed using Solar module (combination of solar cells) which is provided

with irradiance and temperature. According to theoretical knowledge maximum amount of power is obtained from

any solar cell when the irradiance is 1000 W/m2 and temperature is 25oC. The output of this solar module is fed into

MPPT controller which is using P/O algorithm for obtaining maximum power. The DC power obtained from the

solar module is of low voltage level so it is passed to a unidirectional dc-dc step up converter which makes it

suitable for the high voltage DC load.

3.4.1 Simulation of Photovoltaic System

Schematic diagram of Solar powered generation unit along with unidirectional dc-dc converter is designed in

SIMULINK and is shown in Fig.6.2.

Figure.7. Simulation of Photovoltaic System

3.4.2 Output Waveforms of Solar power generation unit

Various output waveforms of solar power generation unit are shown below. Fig.6.3 shows the current waveform.

Average current obtained is 5amps.



Figure 8. Current waveform of Photovoltaic system

Similarly, voltage waveform is shown in Fig.6.4. Average voltage obtained from solar power source is 100 volts.

Figure .9. Voltage waveform of Photovoltaic system

Power obtained from the circuit is shown in Fig.6.5. According to the theoretical study the power obtained in any

circuit is the product of current and voltage in that circuit (5 amps*100 volts=500Watts). Hence, theoretical and

experimental results are verified.

2

Figure 10. Power waveform of Photovoltaic system

3.5 Designing of Wind Power Based Generating Unit

Wind power based generation unit is designed using Wind turbine generator (Permanent Magnet Synchronous

Generator) which is provided with wind speed and pitch angle. Power obtained from wind energy is very fluctuating

due to the varying wind speed. The harmonics are removed using filter circuit. The power obtained from wind

energy source is AC which is then converted and stepped up into DC using AC-DC converter (rectifier). The DC

power obtained from the rectifier is suitable for the high voltage DC load so it is fed to DC link directly.

3.5.1 Simulation of Wind Energy power system

Schematic diagram of Wind powered generation unit along with unidirectional ac-dc converter is designed in

SIMULINK and is shown in Fig.11.



Figure 11. Simulation of Wind energy generation unit

Internal Circuitry of PMSG generator is shown in Fig.12 where various scopes are employed to determine generator

terminal outputs. Wind speed is taken as 12m/s according to references for obtaining maximum power.

Figure.12. Simulation of PMSG



3.5.2 Output waveforms of Wind power generation unit

Output waveforms of wind power generation unit are shown in Fig.13. According to this 3-phase AC output is

obtained by PMSG wind turbine.

(a)

(b)

(c)

Figure 13. 3-Phase Voltage waveforms for wind power generation unit

Output waveforms of Line voltage, Line current and RMS voltage are shown in Fig.14.

Figure 14. Output waveforms of Wind generator terminal (a)

Also, output waveforms of RMS current, AC power from wind turbine and Rotor speed are shown in Fig.15.



Figure.15. Output waveforms of Wind generator terminal (b)

AC voltage obtained from wind turbine generator (Fig.16) is equal to the voltage level required by the DC link. This

AC is fed into rectifier for AC-DC conversion and results are shown in Fig.17.

Figure 16. Output waveforms of AC voltage from Wind turbine

Figure.17. Output waveforms after AC-DC conversion

3.6 Simulation of Energy Storage Unit

The energy storage unit is composed battery and bidirectional converter. When the demand is lower than the

generated amount than to reduce the waste of energy the energy is stored in the battery. Similarly, when sources are

not available for power generation then stored energy is utilized by loads.

Simulation of Energy Storage Unit with Bidirectional Converter

Simulation of Bidirectional DC-DC converter is shown in Fig.5.1 and Fig.5.4. Same block of converter are used in

the simulation of hybrid energy system for storing energy.



3.7 Characteristics of Battery

Discharging characteristics of battery is shown in Fig.18 which shows that with time the amount of charge stored in

the battery is increased as the power is generated in the system.

Figure.18. Charging characteristics of Battery

3.7.1 Output waveforms of Bidirectional Convertor in Conduction Mode

High voltage DC is obtained at the output of bidirectional DC – DC converter which is shown in Fig.19.

Figure.19. Output waveform of BDC in Hybrid energy system

3.8 Connections to DC load

DC load is connected to the output of solar power source, wind power source and energy storage unit. This is an

example of stand- alone system. This system is the basic category of the hybrid energy system.

Simulation of DC Load in Hybrid Energy System

All the three subsystems are collectively connected to the DC link as shown in Fig.20. In which all the connections

are fed directly to the DC load.

Figure.20. Simulation of DC Load in Hybrid Energy System



3.8.1 Output Voltage/Current Waveforms at DC load in Hybrid Energy System

Voltage and current at the DC load are measured using voltmeter and ammeter and the output waveforms are studied

using scope in SIMULINK. Output waveforms of DC voltage and DC current fed into DC load from whole system

are shown in Fig.21 and Fig.6.22 respectively.

Figure.21. Output waveform of DC voltage to DC load

Figure.22. Output waveform of DC current to DC load

3.9 Connections to AC load

DC power obtained from the hybrid energy system is converter into AC using a 3-phase inverter. Output of inverter

is suitable for AC load is connected further. This is also an example of stand- alone system. This system is the basic

category of the hybrid energy system which can be used for domestic applications.

3.9.1 Simulation of AC load in Hybrid Energy System

All the three subsystems are collectively connected to the DC link which in turn is fed into inverter for DC-AC

conversion.

Fig.23 depicts the simulation of AC load in hybrid energy system. The AC load is operating on 50Hz frequency and

50 kW power.

Figure.23. Simulation of AC load in Hybrid Energy System



3.9.2 Output Voltage/Current Waveforms at AC load in Hybrid Energy System

Voltage and current at the AC load are measured using voltmeter and ammeter and the output waveforms are studied

using scope in SIMULINK. Output waveform of inverter at AC load is shown in Fig.24.

3- Phase AC voltage is obtained from inverter and is fed to the load at 50 Hz frequency.

Figure.24. Output voltage waveform at AC load

All the resultant waveforms are depicted in the scope terminal attached to the AC load. Fig.6.20 shows the output

waveforms of DC voltage fed into inverter, output phase voltage of inverter and Load voltage.

Figure.25. Various Output voltage waveforms for AC load simulation

All these waveforms shows that the voltage level obtained in all the cases is similar are is stepped up at the high

voltage DC or AC link for efficient utilization of energy.

IV. APPLICATIONS AND ADVANTAGES

As we know that the energy consumption is growing globally. To meet the demand for electric power and

controlling the depletion of conventional resources, the power obtained from renewable sources is becoming more

popular. Wind and PV energies have experienced one of the tremendous growths (in percentage of 20 % each year)

as compared to others. In renewable energy applications such as fuel cell systems and photovoltaics the demand of

DC–DC converters with higher voltage gain is increasing gradually. Besides requirement of non-isolation and high

step-up voltage gain they also demand for high power density, high efficiency, and minimized cost. The output

voltage delivered by renewable energy sources is in range of around 12 to 70 VDC. So, to connect these to the grid

their voltage level should be stepped up to sufficient level at which the DC/AC conversion can be performed. Higher

efficiency can be attained by reducing duty cycle and reducing voltage stress on components. In non isolated dc-dc

converters efficiency and voltage gain are excellent, even though two transformers are in use. Utilization of



transformer is depicted in high step up dc-dc converter for photovoltaic applications that ensures higher voltage gain

but the interleaved converter topology allows the switches to work with lower duty cycle. Among the other more

advanced topologies push-pull converter with additional snubbers and voltage doubler can be used as a promising

solution. Inductor coupled topologies presented in and provides very compact designs for the dc-dc converters with

high voltage gain. In topology, converter with higher efficiency coupled inductor and charge pump circuits for broad

input photovoltaic AC module applications is implemented which is a compact and robust solution. The designers

have to cope with several time related reliability issues because of utilization of renewable energy sources for many

years. Also, another major issue is to minimize the maintenance and to maximize the energy yield. To produce

sufficient DC bus voltage level high voltage gain is required. Additionally these should be immune to environmental

conditions and operate at wide temperature range. Such necessities of systems create several designing criteria for

step up DC/DC converter for efficiency of overall renewable energy systems.

The advantages of this system includes:

Low operating cost:

One of the important advantages is the negligible operating cost of the system. Since there is no fuel required for the

pump like electricity or diesel, the operating cost is minimal.

Low Maintenance:

A well designed Hybrid renewable energy system requires little maintenance beyond cleaning of panels once a

week. Most vendors provide the post installation service through trained technicians for every cluster, so that the

farmers don’t need to worry about availability of spares or other related problems.

Harmonious with nature:

Another important advantage is that it gives maximum output when it is most needed i.e., both in hot and dry

months.

Flexibility:

Panels can be placed along with the wind turbines on heights to obtain the maximum power.

Applications:

Solar Wind Hybrid Energy Systems are using in almost all field small electric power usage. Some of the

applications of SWHES are given below.

Grid connected: The large power rating of SWHES, where the access of wind and sun irradiation is more,

they can be connected to Grid. In these types of generation, if the system failed to generate power the Grid

will supply the load.

Stand alone: Almost all SWHES applications are stand - alone not connected to the grid.

Street lighting: The foremost application of SWHES is solar street lighting. Solar Street light become as

SWHES lighting. Use of this reduces the load from conventional power plants.

Household: Residential appliances can use power generated through hybrid solar wind energy system.

SWHES are used to supply electricity to different offices or other parts of the building in reliable manner.

Remote Applications: like military services where it is impossible to provide conventional power supply

these SWHES systems are useful.

Ventilation system: The proposed systems are also used for ventilation purposes, these helps in running

Bath fans, floor fans and ceiling fans in buildings.

Power Pump: SWHES can also help to pump the water to any building. DC power operated pump can

circulate the water through your home.

Village Power: The proposed system is very useful in villages which are in valley and on hills, where it is

not possible to send electricity.

On shore: The wind blows more at coastal areas, SWHES are installed near sea and on the boats for power

generation

Commercial: In hotels, tourist places SWHES give the required electric power.

V. CONCLUSION AND FUTURE SCOPE

Solar Wind Hybrid energy Systems become reliable for small power applications. To improve the solar Photovoltaic

power generation efficiency, wind energy is integrated to form as hybrid energy system. The proposed systems help

to reduce air pollution caused by the conventional power generation system. By installing SWHES to every house,

the burden on the conventional power generating system reduces. The storage of the battery will give power for

some time, even no generation takes place by this system. Almost in all field of electric power usage, the SWHES

are being used. It provides the power to inaccessible convention power places. SWHES are more reliable and

efficient energy generating system with less effect on the environment and almost no maintenance. In small utility



areas this SWHES is much preferred. This two energy sources are acting simultaneously to generate electric power.

Load sharing takes place in this proposed system. And it can be operated on their maximum power point. Continuity

of power supply also takes place in this system, if any one failed to generate power the other one will supply the

load. This load monitoring was done by the respective control algorithms. Under this both power generating systems

works to generate the power. By this SWHES the overall system performance is increased and will get continuous

power supply. Results showed that it will be possible for users to use bidirectional converters in the hybrid energy

systems to monitor directly. Further, it will help us to take advantage of the renewable energy sources to provide

more efficient supplies. The output of that converter is stored in battery on one side and on another hand it is given

to the AC loads after getting converted into AC using inverter circuit. Power quality improvement, efficiency

increment is the field on which we can work further and compare the results.

In future if we modify it properly then this system can also use this system in designing micro grids with better

efficiency. Power quality of the power obtained from the bidirectional converter can be improved further. Duty

cycle comparisons can be done for the various convertors to design and select the best converter fot the desired

system. In future the advances in nano technology, improvements in smart grid and power electronics have major

role in implementing solar energy policies. Our government, Research and laboratories, various solar organizations

are working hard to make this energy system a better source for power supply.

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