GRID INTERCONNECTION OF RENEWABLE ENERGY SOURCES WITH PQ
IMPROVEMENT FEATURES AT THE DISTRIBUTION LEVEL
Presenter: B NAGARAJU (12D01D7514)
Under the guidance of
Sri L VIJAY KUMARProfessor ,Electrical and Electronics
Engineering
Electrical & Electronics Engineering DepartmentST.MARYS
COLLEGE OF ENGINEERING AND TECHNOLOGY(Affiliated to JNTUH)
GRID INTERCONNECTION OF RENEWABLE ENERGY SOURCES WITH PQ
IMPROVEMENT FEATURES AT THE DISTRIBUTION LEVELThe Transient
response of the Shunt Active filters (SAF) is very important while
compensating rapidly varying unbalanced and nonlinear loads.
Any change in the load affects the dc link voltage directly
The proper operation of SAF requires variation of the DC link
voltage within the prescribed limits.
Conventionally, a proportional-integral (PI) controller is used
to maintain the dc-link voltage to the reference value
However, the transient response of the conventional PI dc-link
voltage controller is slow.
In this paper, a fast acting dc-link voltage controller based on
the energy of the dc-link capacitor is proposed and proposed shunt
controller method by using SVPWM Technique Mathematical equations
are given to compute the gains of the conventional controller based
on the fast-acting dc-link controllers to achieve similar fast
transient response.
AbstractINTRODUCTIONSOLAR & WIND NON-CONVENTIONAL
ENERGYPOWER QUALITYSHUNT ACTIVE FILTERSSVPWM TECHNIQUESIMULATION
RESULTSCONTENTSWith increasing problems of global warming and the
depletion of fossil fuel reserves, many are looking at sustainable
energy solutions such as RES
Other than hydro power, wind and solar energy holds the most
potential to meet our energy demands
wind energy is capable of supplying large amounts of power but
its presence is highly unpredictable
Similarly, solar energy is present throughout the day but the
solar irradiation levels vary due to sun intensity and
unpredictable shadows cast by clouds, trees etc
The common inherent drawback of wind and photovoltaic systems
are their intermittent natures that make them unreliable.
INTRODUCTION The integration of renewable energy sources and
energy-storage systems has been one of the new trends in
power-electronic technology.
Such hybrid systems, focusing on providing sustainable power to
their loads, do not care much about the quality or flexibility of
power delivered to the grid.
This project addresses dynamic modeling and control of a
grid-connected windPVbattery hybrid system with flexible power
transfer.
Photovoltaic Effect Photovoltaic (PV) is a method of generating
electrical power by converting solar radiation into direct current
electricity using semiconductors that exhibit the photovoltaic
effectsolar panels comprising a number of cells containing a
photovoltaic material.
Assemblies of cells are used to make solar modules, also known
as solar panels.
Photovoltaic cell produces only about one-half volt of
electricity, cells are often mounted together in groups called
modules
PV cells can be strung together in a series of modules or strung
together in a parallel placement to increase the electrical
output.
SOLAR &WIND CONVERSION ENERGYWhen light energy strikes the
solar cell, electrons are knocked loose from the atoms in the
semiconductor material. If electrical conductors are attached to
the positive and negative sides, forming an electrical circuit, the
electrons can be captured in the form of an electric current.
Each PV cell converts about 5 to 15 percent of the sunlight that
hits it into electrical current.
power electronic equipment has especially become much more
sensitive.
Equipment has become less tolerant of voltage quality
disturbances, due to less tolerant of voltage disturbances
equipment is incorrect in operation.Equipment produces more current
disturbances than it used to do. Due to these current distortions
harmonics are generated in power system.Also energy efficient
equipment is an important source of power quality. PURPOSE OF
STANDARDIZATIONAlmost all countrys has standards defining the
margins in which frequency and voltage are allowed to vary.
Other standards limits harmonic current and voltage distortion,
voltage fluctuations,duration of an interruption These are three
reasons for developing power quality standards.
POWER QUALITY
DSTATCOM means Distribution Static Compensator. STATCOM is a
Static Synchronous Compensator, whose output is varied so as to
maintain or control specific parameters of the electric power
system.A STATCOM is a voltage source converter (VSC)-based
device
STATCOM
A voltage-source converter is a power electronic device, which
can generate a sinusoidal voltage with any required magnitude,
frequency and phase angle.
VSC used in adjustable-speed drives, but can also be used to
reduce voltage dips. The VSC is used to either completely replace
the voltage or to inject the missing voltage. The missing voltage
is the difference between the nominal voltage and the actual.
Voltage Source Converters (VSC)
Harmonic Filters may be used to reduce and in some cases,
eliminate harmonics in power system . Non-linear loads such as
rectifiers, converters, home electronic appliances, and electric
arc furnaces cause harmonics giving rise to extra losses in power
equipment such as transformers, motors and capacitorsInstalling
filters near the harmonic sources can effectively reduce harmonics.
active filters, based on power electronic converters with high
switching frequency, may be a more attractive
solution.BenefitsEliminates harmonicsImproved Power FactorReduced
Transmission LossesIncreased Transmission CapabilityImproved
Voltage ControlImproved Power Quality
HARMONICS MITIGATEAn active shunt filter, which is most widely
used to eliminate current harmonics, reactive power compensation ,
and balancing unbalanced currents.
It is mainly used at the load end, because current harmonics are
injected by nonlinear loads.
It injects equal compensating currents, opposite in phase, to
cancel harmonics
It can also be used as a static VAR generator (STATCOM) in the
power system network for stabilizing and improving the voltage
profile
SHUNT ACTIVE FILTERS
Treats the sinusoidal voltage as a constant amplitude vector
rotating at constant frequency.Coordinate Transformation : A
three-phase voltage vector is transformed into a vector in the d-q
frame which represents the vector sum of the three-phase voltage.
This PWM technique approximates the reference voltage Vref by a
combination of the eight switching patterns (V0 to V7).
The vectors (V1 to V6) divide the plane into six sectors (each
sector: 60 degrees)Principle of Space Vector PWMPWM METHODS
where, upper transistors: S1, S3, S5 lower transistors: S4, S6,
S2 switching variable vector: a, b, cThe eight inverter voltage
vectors (V0 to V7)
The eight combinations, phase voltages and output line to line
voltages
BLOCK DIAGRAM
Fig Dstacom with pi control inverter
Fig Dstacom with pi control Inverter
Fig Dstacom pi control Inverter
Fig Dstacom pi control active & reactive Power
Fig Dstacom pi control Voltage
Fig Dstacom pi control vdc
Fig Dstacom with pi control Vs In this paper we have studied and
analyzed the operation and performance of SAF.
This proposed model is implemented using Mat lab Simulink
software and the obtained resultant waveforms
A VSI topology for SAF compensating ac unbalanced and nonlinear
loads
The fast acting dc link voltage controller is suggested to
ensure the fast transient response of the compensator.
The effectiveness of the proposed controller over the
conventional dc link voltage controller and SVPWM Technique are
established through the digital simulation studies.
It is observed from these studies that the proposed dc link
voltage controller gives fast transient response under load
transients.
CONCLUSION