IMPROVING GRID POWER.pptx

7/29/2019 IMPROVING GRID POWER.pptx

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IMPROVING GRID POWERQUALITY WITH FACTS DEVICEON INTEGRATION OF WIND

ENERGY SYSTEMProject Guide:-B.mohan

(Asst. Professor)

By:-

j.Ramakrishna

m.Prathiba

Ch.avinash

Ramprasad

a.himasagar


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ABSTRACT:-

Injection of the wind power into an electric grid affects the

power quality.

The influence of the wind turbine in the grid system concerning

the power quality measurements are-the active power, reactive

power, variation of voltage, flicker, harmonics, and electricalbehavior of switching operation and these are measured

according to national/international guidelines

The performance of the wind turbine and thereby power qualityare determined on the basis of the measurements and the norms

followed according to the guidelines specified. in International

Electro-technical Commission standard, IEC-61400


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In this proposed scheme STATCOM( Static Synchronous

Compensator) at a point of common coupling with a battery energy

storage system to mitigate the power quality issues.

A proper control scheme in wind energy generation system is

required under normal operating condition to allow the proper

control over the active power production. In the event of increasing

grid disturbance, a battery energy storage system for wind energygenerating system is generally required to compensate the

fluctuation generated by wind turbineity, power quality problems.

The integration of wind energy into existing power system presents

a technical challenges and that requires consideration of voltageregulation , stability, power quality problems


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CONTENTS1) Introduction

2) Wind Energy System3) Power Quality

4) FACTS Devices

5) Renewable Energy Source


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INTRODUCTION The modern power system has to confront some major

operating problems, such as voltage regulation, power flow

control, transient stability, and damping of power oscillations,

etc. FACTS devices can be a solution to these problems.

They are able to provide rapid active and reactive power

compensations to power systems, and therefore can be used to

provide voltage support and power flow control, increase

transient stability and improve power oscillation damping.


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BLOCK DIAGRAM


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Wind Energy System:-

Wind is the natural movement of air across the land or sea.

WT convert wind energy in to electric energy which are fed in

to electricity supply systems.

The three main components for energy conversion in WT are

rotor, gear box and generator. The rotor converts the

fluctuating wind energy into mechanical energy and is thus

the driving component in the conversion system.


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SIMULINK MODEL OF WIND FARM


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WT convert wind energy into electrical energy

Main components for energy conversion in WT are1. Rotor 2. Gear Box 3. Generator

Rotor converts the fluctuating wind energy into Mechanicalenergy.

The generator and possibly electronic inverter absorbs themechanical power while converting it in to electricalenergy, fed in to supply Grid


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The generator and possibly an electronic inverter

absorb the mechanical power while converting it intoelectrical energy, fed into a supply grid. The gear box

adapts rotor to generator speed.

At the point of common coupling (PCC) between the

single WT or the wind farm and the grid a circuit

breaker for the disconnection of the whole wind farm

or of the WT must exist


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Power QualityA Power quali ty problem is an occurrence

manifested as a nonstandard voltage, current or

frequency that resul ts in a failure or a mal-

operation of end user equipments

Power Quality I ssue & its Consequences:

Voltage variation

Harmonics

Wind turbine Location in Power System Self Excitation of wind turbine generating System


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One of the most common power quality

problems today is voltage dipsA voltage dip is caused by a fault in the utility

system, a fault within the customers facility or

a large increase of the load current, like

starting a motor or transformer energizing.

Faults due to lightning, is one of the most

common causes to voltage dips on overheadlines.


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FACTS DEVICES Flexible AC Transmission Systems are represented by a

group of power electronic devices.

FACTS devices can be divided into two generations.

Older generation was based on the thyristor valve, wherenewer uses Voltage Source Converters (VSC).

Among the FACTS family, the shunt FACTS devices such as

the STATCOM has been widely used to provide smooth and

rapid steady state and transient voltage control at points inthe network.


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The proposed STATCOM control scheme for

grid connected wind energy generation for

power quality improvement has following

objectives

Reactive power support only from STATCOM to windGenerator and Load.

Simple bang-bang controller for STATCOM to

achieve fast dynamic response.

Unity power factor at the source side.


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STATIC COMPENSATOR (STATCOM) STATCOM system is a static synchronous generator

operated as a static compensator connected in

parallel whose output current (inductive or

capacitive) can be controlled independently of the ACsystem voltage.

These controllers are possible by the high switching

frequency of the IGBT, GTO, IGCT or IEGT

transistors of the power converter. The system

connects to the grid via a transformer.


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The AC/DC power converter is controlled by PWM

techniques.If V=Vs (pu values), no current flows through Rtr and Ltr.

If V> (or )


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The STATCOM is an electronically generated three phasevoltage source that is connected to the AC system via a

shunt transformer When operating as pure STATCOM the generated

voltage is exactly in phase with AC system voltage

If the generated voltage is greater that the terminalvoltage then the device will supply VARs(Capacitivemode) to the system.

If the internal voltage is less than the terminal voltagethe device will absorb the VRS (inductive )

The control system of the STATCOM is extremely fast and

therefore can rapidly change the magnitude and phase ofthe electronically generated voltage


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System operational scheme in gridsystem


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Usually a STATCOM is installed to support electricity networks

that have a poor power factor and often poor voltage regulation.

There are however, other uses, the most common use is for voltagestability.

A STATCOM is a voltage source converter (VSC)-based device,

with the voltage source behind a reactor. The voltage source is

created from a DC capacitor and therefore a STATCOM has very

little active power capability.

However, its active power capability can be increased if a

suitable energy storage device is connected across the DCcapacitor. The reactive power at the terminals of the STATCOM

depends on the amplitude of the voltage source.


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Simulink model of STATCOM


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Voltage controlled STATCOM


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Technical features of STATCOM

Provides fast smooth compensation from inductive to

capacitive in reactive power, also eradicates the reactive

power delivery to the grid. It reads the maximum request to

compensate the power factor and keeps the power factor close

to 1.0 at any time.

Has powerful ability to support the voltage and ability to

withstand short term over load. Provides better support for

improving low voltage ride through characteristics of windturbine. Decreases negative influence which caused by

repetive switching operations by the wind turbine.


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Low power loss, better economical operation.

Faster response time and better effect for repeating

flicker.Produces no harmonic and filtering partial load

harmonic with out amplifying harmonic and noharmonic resonance.

It has better safety and stability as it is independenton system parameters.

Less space for installation, also provides flexibleinitialization, equipment can be installed indoor or

outdoor.Low loss and low noise


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Applications of STATCOM: Voltage control Active harmonics cancellation and Flicker mitigation

Utilities with weak grid knots or fluctuating reactive

loads

Unbalanced loads

Arc furnaces

Industrial mills

Mining shovels & hoists


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STATCOM Advantages:

Continuous and dynamic voltage control High dynamic and very fast response time

Maximum reactive current over extended voltage

range

High efficiency

Single phase control for unbalanced loads

Enhanced ride-through capability

High reliability and availability


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STATCOM CONTROL SCHEMES:


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To control the power flow in a AC transmission line to

1. enhance power transfer capacity2. To change power flow under dynamic conditions

(subjected to disturbances such as sudden increase in

load ,line trip or generator outage) to ensure stability and

security.

The stability can be affected by growing low frequency ,

power oscillations (due to generator rotor swings) loss of

synchronism and voltage collapse caused by major

disturbances.


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STATCOM supply require reactive current even at low

values of the bus voltages and can be designed to have builtshort term over load capability.

The controller of a STATCOM operates the converter in a

particular way that the phase angle between the convertervoltage and the transmission line voltage is dynamically

adjusted and synchronized so that the STATCOM generates

or absorbs desired VAR at the point of coupling connection.


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System operational Scheme in a grid

system


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Three phase injected inverter current output:-


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SUPPLY VOLTAGE AND CURRENT AT PCC:-


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DC LINK VOLTAGE & CURRENT THROUGH

CAPACITOR:-


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a) Source Current. (b) Load Current. (c) Inverter Injected Current. (d) Windgenerator (Induction generator) current


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CONCLUSION:

In this we present the FACTS device (STATCOM) -based

control scheme for power quality improvement in windgenerating system on integration to the grid and withnonlinear load.

The power quality issues and its consequences on theconsumer and electric utility are presented.

The operation of the control system developed for theSTATCOM in MATLAB/SIMULINK for maintaining the powerquality is to be simulated. It has a capability to cancel out theharmonic parts of the load current.

It maintains the source voltage and current in-phase and

support the reactive power demand for the wind generatorand load at PCC in the grid system, thus it enhance theutilization factor of transmission line.


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IMPROVING GRID POWER.pptx

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