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