wind energy based svpwm based shunt active power filter for

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ISSN 2348–2370

Vol.08,Issue.15,

October-2016,

Pages:2933-2940

Copyright @ 2016 IJATIR. All rights reserved.

Wind Energy Based SVPWM Based Shunt Active Power Filter

for Compensation of Power System Harmonics SHAIK KHADAR SHAREEF

1, A. VENKATESWARLU

2

1PG Scholar, Dept of EEE, Laqshya Institute of Technology & Sciences, TS, India, E-mail: [email protected]

2Associate Professor, Dept of EEE, Laqshya Institute of Technology & Sciences, TS, India, E-mail: [email protected].

Abstract: In this project, an improved SVPWM technique

based shunt Active Power Filter is presented based on the

effective time concept. The effective time concept eliminates

the trigonometric calculations and sector identification,

thereby it reduces the computational effort. A novel control

method for shunt active power filters using SVPWM is

presented. In the proposed control method, The APF

reference voltage vector is generated to instead of the

reference current, and the desired APF output voltage is

generated by space vector modulation. The control algorithm

is simple and can be realized by a low cost controller. The

active power filter based on the proposed method can

eliminate harmonics, compensate reactive power and balance

load asymmetry. Wind power is the use of air flow through

wind turbines to mechanically power generators for

electricity. Wind power, as an alternative to burning fossil

fuels, is plentiful, renewable, widely distributed, clean,

produces no greenhouse gas emissions during operation,

uses no water, and uses little land. The net effects on the

environment are far less problematic than those of non

renewable power sources. Wind farms consist of many

individual wind turbines which are connected to the electric

power transmission network. In recent times, SVPWM

technique was applied for active power filter (APF) control

application, as the APF is nothing but of a current controlled

VSI. the efficacy of the APF with the improved SVPWM

based control strategy by using MAT Lab/Simulink.

Keywords: Active Power Filter, Instantaneous Power

Theory, Self Tuning Filter, Harmonics, Non Linear Load.

I. INTRODUCTION

In Variable Speed application, Voltage Source Inverter is

commonly used to supply a variable frequency variable

voltage to a three phase induction motor. In this PWM drives

are more efficient and typically provide higher levels of

performance. A suitable Pulse Width Modulation technique

is employed to obtain the required output voltage of the

inverter. The most common AC drives today are based on

sinusoidal pulse-width modulation SPWM. . Induction motor

is rugged, reliable, and single-fed machine; it can directly

absorb the reactive power from the utility with this device,

we can get two advantages: one is that we can get a low start

current; the other is that we can change the motor speed

conveniently by controlling the output frequency of the

ASD. Many research works are focusing in the development

of the efficient control algorithms for high performance

variable speed induction motor (IM) drives. Induction motor

has been operated as a work horse in the industry due to its

easy build, high robustness and generally satisfactory

efficiency. Recent development of high speed power semi

conductor devices, three phase inverters take part in the key

role for variable speed AC motor drives.

Traditionally, Three Phase inverters with six switches

(SSTP) have been commonly utilized for variable speed IM

drives this involves the losses of the six switches as well as

the complexity of the control algorithms and interface

circuits to generate six PWM logic signals. So far

researchers mainly concentrated on the development of new

control algorithms. However, the cost, simplicity and

flexibility of the overall drive system which are some of the

most important factors did not get that much attention from

the researchers. That is why, despite tremendous research in

this area, most of the developed control system failed to

attract the industry. Thus, the main issue of this work is to

develop a cost effective, simple and efficient high

performance IM drive. In this paper, an improved SVPWM

based shunt APF topology is proposed. The harmonic

currents are extracted by synchronous reference frame (SRF)

theory and the switching instants for each inverter arm are

computed directly using the effective time relocation

algorithm. Simulation results in MATLAB/Simulink

environment demonstrate the improvement in the

performance of the proposed SVPWM based shunt APF.

II. SHUNT APF TOPOLOGY

The core part of the shunt APF is shown in Fig.1. This

topology consists of two-level VSI coupled with DC

capacitor, which is connected in shunt to the nonlinear load

at the Point of Common Coupling (PCC) through a ripple

filter. Here, Vsa, Vsb, Vsc represent the source voltages. Load

currents drawn by the nonlinear load are represented as ila,

ilb,ilc. Source currents and active filter currents are

represented as isa, isb, isc and ifa, ifb, ifc respectively. Capacitor

C is the energy storage element on the dc side to maintain

the dc bus voltage Vdc constant. The compensation signals

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SHAIK KHADAR SHAREEF, A. VENKATESWARLU

International Journal of Advanced Technology and Innovative Research

Volume. 08, IssueNo.15, October-2016, Pages: 2933-2940

are generated based on the improved SVPWM based

controller.

Fig.1.Configuration of Improved SVPWM based shunt

APF.

The compensation currents of the APF are given by

(1)

The voltage-source PWM Inverter with a current controller

should provide the ability of controlling the harmonic

currents. The control circuit should extract the harmonic

current from the nonlinear load, not only in steady states but

also in transient states. As for three phase APFs, the

instantaneous reactive power theory (IRPT) also called as p-

q theory [1] or the synchronous reference frame (SRF)

theory [6] are generally applied for estimation of the

necessary compensation signals, and the PWM strategies for

generation of gating signals as shown in Fig.2. In the

proposed shunt APF topology, SRF theory is used for

harmonic current extraction and SVPWM technique is used

to generate the switching signals. Furthermore, SVPWM

does not require the triangle waveform generation circuit and

is more suitable for realization in digital control circuits.

Here Vsa & isa are the phase-A source voltage and source

current and Rs & Ls are the internal source resistance and

inductance. Esa is the instantaneous voltage of phase A at

PCC.

Fig.2.Single-phase equivalent circuit of APF topology.

Vfa, ifa & Lf are the phase A APF voltage, current and

inductance, ila is nonlinear load current. The above network

can be described by the following equations in terms of APF

voltage Vfa and current ifa.

(2)

Similarly

(3)

(4)

From the above equations the APF voltages in a-b-c

frame can be written as

(5)

The source current is,abc is forced to be free of harmonics by

suitable voltages from the APF, and the harmonic current

emitted from the load is then automatically compensated.

The proposed APF is connected into the network through the

inductor Lf. The function of Lf is to attenuate the high

frequency switching ripple generated by APF and to connect

two AC voltage sources of the inverter and the supply

system.

III. SYNCHRONOUS REFERENCE FRAME THEORY

FOR HARMONIC EXTRACTION

In this work SRF is used for harmonic current extraction

[6]. The block diagram of proposed shunt APF control

scheme shown in Fig.3. In order to maintain sinusoidal

source currents with unity power factor at PCC, the source

has to supply only the fundamental real component of load

current. Hence, the harmonics, reactive component of load

current should be supplied from APF. Therefore, the load

currents are sensed and transformed to dq0 reference frame

as follows

(6)

Fig.3.Proposed SVPWM control for APF topology.

Wind Energy Based SVPWM Based Shunt Active Power Filter for Compensation of Power System Harmonics



The harmonic currents for each of the three phases are

derived by removing the fundamental frequency component

from load currents. Thus, the reference currents normally

consist of harmonic components drawn by the load. A low

pass filter (LPF), with cut off frequency of 50Hz is used to

extract ild. Here, ild corresponds to harmonic load currents in

a-b-c frame. The loss component of VSI is idc,d must be

added to i ld in order to acquire complete d-axis reference

filter current. As Ilq, il0 currents must be supplied directly,

LPFs are not required in q-axis and 0-axis controller as

shown in Figure.3. Therefore, the dq0 reference harmonic

currents are given by

(7)

The dq0 transformation of (5) generates the following set

of equations.

(8)

(9)

(10)

Where, Vfd, Vfq, Vf0 are the variables to be controlled, in

order to achieve the desired filter currents at PCC in dq0

frame, ω is the system frequency and ifd, ifq and if0 are the

stationary frame reference currents. Esd, Esq and Es0 are the

stationary frame reference voltages. Neglecting the zero

sequence terms, the dynamics of the APF ac side variables in

an SRF (dq frame) is derived. Since the d and q components

are orthogonal. Hence Vfd and Vfq from Equation (8) are

considered for SVPWM switching signals generation.

IV. IMPROVED SVPWM ALGORITHM FOR APF

The voltage space vector synthesization is critical in the

conventional SVPWM method. As it uses Clarke

transformation to transform the reference voltages to d-q

coordinates in order to generate reference vectors.

Subsequently, the reference vectors are synthesized by some

optimally selected basic vectors with specific time duration.

In that method, the sectors of reference vectors are

determined by their phase angles, and the time duration of

basic vectors are calculated through the computation of

phase angles and reference vectors. As these computations

involve huge quantities of irrational numbers and

trigonometric functions, the computation burden would be

enormous. These operations may bring about major

calculation errors which would corrupt the performance of

shunt APF. To solve this problem, an effective time concept

based SVPWM is used to generate the switching signals. It is

possible to reconstruct the actual gating time without

separation and recombination effort. The switching state

diagram of the VSI is shown in Fig.4. The six non-null states

are represented by space vectors mathematically represented

as follows

(10)

Fig.4.VSI switching states vectors.

The APF reference voltages Vsa*, Vsb* and Vsc* for each

phase are found from the stationary reference voltages.

(11)

In order to obtain the actual switching time directly from

the APF phase voltages, the stationary reference frame

voltages are utilized and effective times are transformed to

the phase voltages using equation (11).

(12)

From the equations (11) and (12), the effective times T1,

T2 can be calculated by the time difference between the

times Tsa, Tsb and Tsc matching to the phase voltages.

Furthermore, in the remaining sectors case, the effective

times can be substituted with the phase voltage times in the

same method described above. This result, demonstrates that

the effective time calculated in the conventional SVPWM is

the difference between two applied times resultant to the

phase voltage. Hence, despite of the sector location of the

reference vector, the resultant times for each phase voltages

are defined as following.

(13)




The effective time Teff will be defined as the time

duration between Tmax and Tmin, and the effective voltage is

supplied to the VSI during this time interval. Therefore, the

actual switching times for each VSI arm can be obtained as

follows.

(14)

To allocate the zero voltage symmetrically during one

sampling period, the offset time Toffset is calculated as

follows. The switching pulse pattern is shown in Fig.5. By

using the effective time concept, the actual switching times

can be directly computed from the stationary reference frame

voltages. Therefore, the computation effort of the proposed

PWM method is greatly reduced. With this PWM method

the Harmonic compensation signals are generated at PCC

using VSI.

Fig.5. Proposed shunt APF switching pattern.

(15)

(16)

V. WIND ENERGY

Wind is a form of solar energy. Winds are caused by the

uneven heating of the atmosphere by the sun, the

irregularities of the earth's surface, and rotation of the earth.

Wind flow patterns are modified by the earth's terrain,

bodies of water, and vegetative cover. This wind flow, or

motion energy, when "harvested" by modern wind turbines,

can be used to generate electricity.

How Wind Power Is Generated: The terms "wind energy"

or "wind power" describe the process by which the wind is

used to generate mechanical power or electricity. Wind

turbines convert the kinetic energy in the wind into

mechanical power. This mechanical power can be used for

specific tasks (such as grinding grain or pumping water) or a

generator can convert this mechanical power into electricity

to power homes, businesses, schools, and the like.

Wind Turbines: Wind turbines, like aircraft propeller

blades, turn in the moving air and power an electric

generator that supplies an electric current. Simply stated, a

wind turbine is the opposite of a fan. Instead of using

electricity to make wind, like a fan, wind turbines use wind

to make electricity. The wind turns the blades, which spin a

shaft, which connects to a generator and makes electricity.

Wind Turbine Types: Modern wind turbines fall into two

basic groups; the horizontal-axis variety, like the traditional

farm windmills used for pumping water, and the vertical-axis

design, like the eggbeater-style Dairies model, named after

its French inventor. Most large modern wind turbines are

horizontal-axis turbines as shown in Fig.6. Turbine

Components Horizontal turbine components include:

blade or rotor, which converts the energy in the wind to

rotational shaft energy;

a drive train, usually including a gearbox and a

generator;

a tower that supports the rotor and drive train; and

Other equipment, including controls, electrical cables,

ground support equipment, and interconnection

equipment.

Fig.6. Analytical showing of wind energy system.

Turbine Configurations: Wind turbines are often grouped

together into a single wind power plant, also known as

a wind farm, and generate bulk electrical power. Electricity

from these turbines is fed into a utility grid and distributed to

customers, just as with conventional power plants.

Wind Turbine Size and Power Ratings: Wind turbines are

available in a variety of sizes, and therefore power ratings.

The largest machine has blades that span more than the

length of a football field, stands 20 building stories high, and

produces enough electricity to power 1,400 homes. A small

home-sized wind machine has rotors between 8 and 25 feet

in diameter and stands upwards of 30 feet and can supply the

power needs of an all-electric home or small

business. Utility-scale turbines range in size from 50 to 750

http://windeis.anl.gov/guide/basics/turbine.html




kilowatts. Single small turbines, below 50 kilowatts, are used

for homes, telecommunications dishes, or water pumping.

Wind Energy Resources in the United States: Wind

energy is very abundant in many parts of the United States.

Wind resources are characterized by wind-power density

classes, ranging from class 1 (the lowest) to class 7 (the

highest). Good wind resources (e.g., class 3 and above,

which have an average annual wind speed of at least 13

miles per hour) are found in many locations. Wind speed is a

critical feature of wind resources, because the energy in wind

is proportional to the cube of the wind speed. In other words,

a stronger wind means a lot more power.

A. Advantages and Disadvantages of Wind-Generated

Electricity

A Renewable Non-Polluting Resource: Wind energy

is a free, renewable resource, so no matter how much is

used today, there will still be the same supply in the

future. Wind energy is also a source of clean, non-

polluting, electricity. Unlike conventional power plants,

wind plants emit no air pollutants or greenhouse gases.

According to the U.S. Department of Energy, in 1990,

California's wind power plants offset the emission of

more than 2.5 billion pounds of carbon dioxide, and 15

million pounds of other pollutants that would have

otherwise been produced. It would take a forest of 90

million to 175 million trees to provide the same air

quality.

Cost Issues: Even though the cost of wind power has

decreased dramatically in the past 10 years, the

technology requires a higher initial investment than

fossil-fuelled generators. Roughly 80% of the cost is the

machinery, with the balance being site preparation and

installation. If wind generating systems are compared

with fossil-fuelled systems on a "life-cycle" cost basis

(counting fuel and operating expenses for the life of the

generator), however, wind costs are much more

competitive with other generating technologies because

there is no fuel to purchase and minimal operating

expenses.

Environmental Concerns: Although wind power plants

have relatively little impact on the environment

compared to fossil fuel power plants, there is some

concern over the noise produced by the rotor

blades, aesthetic (visual) impacts, and birds and bats

having been killed (avian/bat mortality) by flying into

the rotors. Most of these problems have been resolved or

greatly reduced through technological development or

by properly sitting wind plants.

Supply and Transport Issues: The major challenge to

using wind as a source of power is that it is intermittent

and does not always blow when electricity is needed.

Wind cannot be stored (although wind-generated

electricity can be stored, if batteries are used), and not

all winds can be harnessed to meet the timing of

electricity demands. Further, good wind sites are often

located in remote locations far from areas of electric

power demand (such as cities). Finally, wind resource

development may compete with other uses for the land,

and those alternative uses may be more highly valued

than electricity generation. However, wind turbines can

be located on land that is also used for grazing or even

farming.

VI. SIMULATION RESULTS

The proposed shunt APF topology presented in this paper

is simulated with MATLAB/Simulink sim power system

toolbox. The performance of the proposed SVPWM based

shunt APF under the application of non-linear loads is shown

in Fig.12. It shows the source voltages at PCC, load currents,

compensated source currents and injected filter currents

respectively. The load currents and the source currents are

same before compensation. After employing the shunt APF

the simulation results shows that the source currents are

sinusoidal at PCC as shown in Figs.7 to 17.

Case1: Without APF

Fig.7.Matlab/Simulink model of without shunt active

power filter for compensation of power systems

harmonics.

Fig.8. Simulation waveform for three phase source

voltage and current, load current.




Fig.9. Simulation waveform for output waveform of

power factor.

Case2: With APF

Fig.10.Matlab/Simulink model of shunt active power

filter for compensation of power systems harmonics.

Fig.11 Simulation waveform for three phase bus voltages,

currents, load current and compensating currents.

Fig 12 Simulation waveform for output waveform of

power factor.

Fig.13 FFT analysis of without shunt APF THD-25.37%.

Fig.14.FFT analysis of with shunt APF THD-1.21%.




Case3: with APF and Wind Turbine

Fig.15. Simulation model of APF with wind turbine.

Fig.16. Simulation waveform for Source voltage, current

and line current.

Fig.17. Simulation waveform for load current.

VII. CONCLUSION

This paper presents a three phase three wire shunt active

power filter as a reliable and cost-effective solution to power

quality problems. When the active filter is installed at a

distorted and unbalanced distribution network, the harmonic

are compensated by the active filter. The main advantage in

this proposed method is incorporated V/F based induction

motor control with SVPWM based inverter. So that the

advantages in 3-level with SVPWM as increased the

performance and life time of drive. These advantages allow

implementing controllers for electric vehicles; because,

mainly electric vehicles need high starting torque so this is

produce the required torque with minimum torque ripples

and in electric vehicles, operation of drive is depends on

variable torque with constant speed applications as well as

variable speed with constant torque application.

VIII. REFERENCES

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[2] F. Z. Peng, “Application issues of active power filters,”

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[5] Z. Chen, Y. Luo, and M. Chen, “Control and

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active power filter." In Proc. 2004 IEEE 11th Harmonics and

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Author’s Profiles:

Shaik Khadar Shareef (Electrical Power

Systems) Pursuing in Laqshya Institute of

TechnologySciences,Talikella(V),Khammam,

Telangana, India.

Email id: [email protected].

Mr. Venkateswarlu Ambhoji was born in

India in the year of 1979.He received B.Tech

degree in Electrical and Electronics

Engineering in the year of 2003&M.Tech

degree in power electronics in the year of

2010 from JNTUH, Hyderabad. He is

currently pursuing Ph.D. degree in electrical engineering.

His research interests are in the area of power systems

especially generation, transmission, distribution and

utilization of electrical energy. He is a professional member

of IEEE and a member of Power and Energy Society (PES)

since 2011.He is acting as counselor for LITS -IEEE student

branch, Email id: [email protected], Blog Spot id:

www. powerbash.blogspot.com.

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wind energy based svpwm based shunt active power filter for

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