Abstract— in hydro, nuclear or thermal power stations

 

 

Abstract— Dynamic stability analysis
of hybrid system comprising hydro power and solar power generation, integrated
into a distribution power grid.A Super Capacitor (SC) is utilized to smooth the
generated power delivered to the distribution power grid

Keywords—Hydro
turbine;Hydro generator;Solar panel;Boost

Converter;Super
capacitor;Utility grid;Power grid

                                                                                                                                                               
I.      Introduction

Renewable energy is collected from variable resources. It  often provides energy in electricity
generation. Solar and hydro energy play a major role in renewable energy
sources. Solar energy has the greatest potential of all the sources of renewable
energy. Solar energy is radiant light and heat from the sun that is harnessed
using a range of ever-evolving technologies such as solar heating, photo
voltaics,solar pumping, etc.., Water is the main soures of hydro power
generation. The kinetic energy of the flowing water strick the  blades or vanes, it starts turns inside the
hydraulic turbine, then, it converted into mechanical energy. In the hybrid
system of hydro and solar energy, to achieve the maximum power. When combining
both hydro and solar, power fluctuation will be occured. By using the super
capacitor  power fluctuation will be reduced
used to reduce kinetic energy.To balancing a two energy sources that will be
produce a unstable condition by using of supercapacitor to reduce this problem.

HYDRO ENERGY

Hydro power plant is a conventional renewable energy source. It has basically its two main sections, firstly the mechanical part
of the plant which includes hydraulic turbine, penstock, controller, hydraulic
servo motor, control valve etc.

 

Fig.1.Hydro Turbine model

Second part
of the plant is electrical section which mainly consists of generator and load.To analysis a generator part transmute
mechanical energy to electrical power. HYDRO TURBINE
GOVERNOR is combination of hydraulic turbine and controller.Modelling of hydroturbine describing variation in flow and developed mechanical power
with respect to the turbine speed, gate opening and runner blade movement of
hydro turbine. Synchronous generators or alternators are
synchronous machines used to convert mechanical power to ac electric power.
Synchronous machines are used widely as generators of electrical power. Large
machines generating electrical power in hydro, nuclear or thermal power
stations are the synchronous generators. They can generate active and reactive
power and has an important role in voltage control technic.

SOLAR ENERGY

Solar energy
has the especially potential of all the sources of  renewable energy and if only a minimum level
of energy could be used , it will be one of the most important supplies of
energy especially when other sources in the country have depleted. Energy comes
to the earth depending on the sun radiation level. The
solar panel can be used as a device of a larger photovoltaic system to generate
and supply electricity in commercial and suburban applications. Each panel is
rated by its DC output power. Solar panels useto take a light energy (photons)
from the sun to generate electricity through the photovoltaic effect. The
majority of modules use wafer based crystalline silicon cells or thin-film
cells based on cadmium telluride or silicon. The structural (load carrying)
member of a module can either be the upper layer or the back layer. Cells must also be protected from mechanical damage and moisture.

 

SUPER
CAPACITOR

Supercapacitor is a trendy  energy storing device, storing very high value
of electric capacitance in a very flatten structure. They are rated in farads,
and offers thousands of times higher storing capacity than the electrolytic
capacitor. They are also known as Ultra capacitors and Double layer capacitors.
Differs with the convention energy deposit  methods of capacitors, that they are not made
up of dielectric material. They store energy in plates filled with double layer
of same substance.This allows for separating the charge without the need for a
dielectric, the plates are fill up  with
a much larger surface area resulting in high capacitance .The supercapacitor is
faultless for energy storage that undergoes frequent charge and discharge
cycles at high current and short duration. Supercapacitors have much longer life than that that Lithium
batteries, normally of 10 to 20 years.Thay have very high charging rate, can be
charged within seconds. Supercapacitors can be easily installed and offers easy
interface with other devices with adaptable mountings.Super capacitors have
very fast transient response as compared to the commonly available lithium ion
batteries.SC used to maintain a stable operation of connecting two energy
sources.

DISTRIBUTION POWER GRID

                An electrical
grid  is a combination network of network delivering electricity  to consumers. It
consists of Generating stations,Transmission and Distribution. Generation
consist of hydro and solar power combination.To transmit a power generation to
distribution to maintain stable condition with help of super capacitor.DC-link
connected to the converter circuit that output passing through the inverter.
That inverter output is connected to the transformer(step up) power deliver to
the Transmission line. Two-way ?ows of electricity and information could
improve the delivery network is called an utility grid. The protection system
of a utility grid provides grid reliability analysis, failure protection, and
security and privacy protection services. While the additional communication
infrastructure of a smart grid provides additional protective and security
mechanisms, it also presents a risk of external attack and internal failures.

An important problem in unmanageable
generation sources such as photovoltaic and hydro is their power fluctuation 

Generation variability can be moderated through
the comprehensive  of various systems.
This method is limited in small grids, isolated systems or grids with high
penetration of renewable energy sources so for this purpose can limit the
percentage of renewable energy sources in the grid.

BLOCK
DIAGRAM

Fig.2

The hydro power vs solar
power generation connected to the  distribution power grid. The PV system is
connected to a common dc link through a dc-dc boost converter. The hydro power
is connected to a dc link through an inverter circuit because of  output voltage of AC will be converted to DC
with help  of the inverter circuit. A
Super Capacitor (SC) is act as a major role of smooth the generated power
delivered to the distribution power grid. To achieve
the maximum power extractions from PV array and hydro power generation system

ANALYSIS OF HYDRO AND SOLAR

Hydro: A Francis turbine is considered in this
paper. It is referred to a fixed head and a constant water flow. It is assumed
that water flow variations are very slow compared to the drive dynamics. The
turbine model is a basic one, i.e. it includes neither blade pitch control nor
upstream guide vane one. According to these assumptions, hydro power turbine
behavior may be taken into account by means of simplified static mechanical
characteristics represented in Fig.2 for a fixed rate of flow.  

The modelling of micro hydro power plant is done
in this thesis by using MAT LAB/Simulation. Introduction of micro hydro power
plant reduces a lot of burden without any adverse effect on environment while
meeting the localized power requirement. The simulation results shows that with
proper choice of governing system for micro hydro power plant leads to proper
load sharing, constant voltage output and constant speed with variation of load
values. This leads to an economical operation of the system.

The main motive of this
proposed work is an efficient design of solar panel for constant
Current-Voltage (V-I) characteristics of a Photovoltaic array of various
environmental conditions like different radiance and temperature. To nominate a
new model uses constant environmental condition in combination with actual
solar radiation and ambient temperature. The new model is developed on Mat
lab-Simulink platform for calculating and analyzing the power output from a PV
panel by taking the values of current and voltage with constantly varying solar
radiation at any geographical location and different day The output power of
solar panel is directly given to dc/dc controller in order to reduce circuit
complexity.

MAT LAB SIMULATION

               In order to compensate the power
fluctuations from the HPGS and the PV array, the SC will continuously exchange
with the dc link a power grid. The difference between the power generated by
both the renewable sources and the power fed to distribution power grid. It
should be noticed that when performing the sizing of the SC, the power profiles
of the HPGS and the PV array must be given in advance and the sum of their
average is taken as the power fed to the distribution power grid. MATLAB is a
powerful electrical engineering software tool that allows engineering to build
electrical models in Simulink environment and change their operating
conditions.

 

Fig
3. SIMULATION MODEL OF HYBRID SYSTEM

 

PV pannel simulation model   PV array was operating very close to the
peak points under the varying solar condition.The PV array is composed of
several PV cells interconnected in series.If required voltage level that cell
arrangement will be varry.Depending on the cell connected in series/parallal
connection required current and voltage collected from the PV cell.

                Boost
converter simulation model:The DC-DC boost converter was use to convert the
variable DC input to a fixed DC output voltage at a required voltage level.The
output of the PV pannel is varriable DC voltage that will be converted to fixed
DC voltage with help of boost converter.

Hydro power plant: The simulation model can be build individual
sub-model like hydro power plant combination of turbine, governor, synchronous
generator, excitation system and RLC loads are connected together.The output of
generating electrical power depending on the rotating speed of turbine.So the
speed and electromagnetic torque will be measured

That output of hydro power plant is pure form of AC voltage that
will be connected to supply through a DC link so that output power convertered
into Dcwith help of  converter
circuit.The combination of converter circuit design by IGBT power electronic
device because of various kind of application like a transistors have low ON
resistance,high voltage capacity, fast switchinf action and various high level
of voltage applications like PWM,SMPS, variable speed control,AC to DC
converter power by renewable energy sources.

Super capacitor simulation model:The super capacitor is combination
with the control scheme to improve the performance of hydro and pv systems.If
any disturbance will be occur in the hybrid system it will be produce a fluctuation
in systems.At the time of period that system may go on to unstable condition.
To prevent this fluctuation condition with help of  super capacitor is placed.

The variable-speed hydro power plant together with SCESD allows
compensating and smoothing the fluctuating wind power, when connected to the
grid. The discharge strategy attempts to maintain the SC at their lowest
operational voltage (half rated voltage) to make available the SC energy
capacity for absorbing power peaks. Once the generator power exceeds a predetermined
value(dependent on the sea state), the SC prevent any excess power ?owing to
the grid and absorb the difference. Once the input power drops below this
value, the SC maintain this power to the grid until the minimum voltageis achieved.

Grid simulation model: Power fluctuations occur in the
main grid under unbalances condition utility grid maintain a stable condition. Advanced electricity generation,
delivery, and consumption of electric power with help of utility grid.

Solar Simulation:The PV array was operating very close
to the peak points under the varying solar condition.The PV array is composed
of several PV cells interconnected in series. The DC-DC boost converter are
used to convert the unregulated DC input to a controlled DC output at a desired
voltage level.

 

 

   Fig 4. VOLTAGE AND CURRENT OF PV PANEL

Hydro: The simulation
model can be build individual sub-models like hydro turbine governor,
synchronous generator, excitation system and 3-phase RLC load are now connected
together to form the complete block diagram of 
hydro power plant.

 

Fig 5:ELECTROMAGNETIC TORQUE OF HT

The output power of generator depending on the turbine
speed so the speed and electromagnetic torque will be measured.

Fig6:Stator Three Phase Current
Characteristics  at Steady State (in
y-Axis Current in pu and in x-Axis Time in Sec)

The speed governing system of
turbine adjusts the generator speed based on the feedback signals of the
deviations of both system frequency and power with respect to their reference
settings. This ensures power generation at synchronous frequency

       Fig 7: VOLTAGE OF
HYDRO GENERATOR

The simulation results shows that
with proper choice of governing system for micro hydro power plant leads to
proper load sharing, constant voltage output and constant speed with variation
of load values. This leads to an economical operation of the system.
Introduction of micro hydro power plant reduces a lot of burden without any
adverse effect on environment while meeting the localized power requirement.

 

Fig 7. STATE OF CHARGE

The physical phenomena associated with supercapacitor charging
create unobservable internal states of charge(SOC)

 

Fig 8:OUTPUT VOLTAGE ACROSS SC

For filtering purpose connected a thyristor circuit give the gate
pulse signal.Then the output fed to the super capacitor.output wave form
displayed by using of scope.super capacitor paves the way for smoothing power
fluctuation of hybrid system

 

Fig 9: BEFORE SUPER CAPACITOR

 

 

Fig 10:AFTER SUPER CAPACITOR

 

 

 

Power fluctuations occur in the main grid under
unbalances condition utility grid maintain a stable condition

Fig 11: GRID VOLTAGE

 

CONCLUSION

           The dynamic stability analysis
results of a hybrid hydro and PV system integrated into a distribution power
grid have been presented. An SC-based energy-storage system has been employed
to support for smoothing out the power fluctuations. A control scheme has been
proposed aiming to suppress the power fluctuations from feeding to the
distribution power grid and maintain stable operation of the studied system
while achieving the maximum power extractions from the PV array and the hydro
power-generation system. Both modal analysis and MATLAB simulations of the
studied system have been performed to examine the dynamic performance of the
studied system under the operating conditions. 
It can be concluded from the simulation results that the proposed
control scheme has the ability to maintain stable operation of the studied
system under various operating conditions while extracting the maximum power
from both the renewable-energy sources. It can also be concluded from the
simulation results that the SC combined with the proposed control scheme can
effectively smooth out the power fluctuations of the studied hybrid hydro and
PV system. For future  scope to a floating of solar array or floating
of  solar panel  refers to an array of photovoltaic
panels on a
structure that floats on a body of water. In order that the renewable
energy generated
is not wasted, and does not become negatively disruptive to the overall energy
system, battery storage should be installed between the point of generation and
the grid system. 

 

 

 

 

 

 

 

 

 

 

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