introduction

A dissertation REPORT ON

load flow analysis on statcom incorporated interconnected power system network using Newton raphson method

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Session: 2013-14

Submitted to: Submitted by: Mrs Aparna Chaturvedi Kapil Deo Bodha Assistant Professor II Year M.Tech (Electrical Engineering ) Power System 10EIMPS602contentsIntroduction

Literature Survey

Objective

Problem formulation

Results

Conclusion & Future Scope introduction This presentation discusses about the use of FACTS controller & STATCOM at various location in IEEE bus systems. Newton Raphson Load Flow studies is used to access the effect of STATCOM on power system viz.

Effect on Nodal Voltage Magnitude.

Active and Reactive Power flows in the network.

Effect on Generator Active and Reactive Power generation/absorption.

STATCOM model for load flow is developed using MATLAB code The Result obtained is compared with the Load flow study of bus system without FACTS devices based on that a conclusion is drawn whether the inclusion of STATCOM improves the performance of Power System networks or not.Literature surveyThe survey is differentiated into following parts

FACTS & its Applications in Power Systems

Series FACTS devices

Shunt FACTS devices

Inclusion of FACTS devices in Load Flow Study

Optimal Allocation of FACTS devices

Some advanced FACTS devices

objectiveTo study & Model Newton Raphson Load Flow in MATLAB

To study & Model various IEEE bus Systems in MATLAB

To Model STATCOM for load flow studies

To perform Newton Raphson Load Flow Analysis ( with and without STATCOM)

To make comparative analysis of the simulation result

LOAD FLOW STUDIESIt is of great importance in planning and designing the future expansion in a Power System.

It determines the best operation of existing systems.

It gives information about Magnitude & Phase angle of Voltage at each bus and real and reactive power flowing in each line.

All utility companies employ Power Flow programs to get information about the steady state of the system.

Development of Power flow eq.The Current & Voltage equation in matrix form will be as follows:-

Where and

Putting their values in equation ( S= Complex Power )

Development of power flow eq. Now complex power can also be written in the form of voltage and current and can be expressed as follows-

Equating Real & Imaginary terms

Development of load flow eq.This Pcal and Qcal are calculated through Power Flow problem.

PScheduled and QScheduled are the scheduled real and reactive power at bus and are known quantity.

P = Pscheduled Pcal = 0 Q = Qscheduled Qcal = 0 These are the Mismatch Power Equation and are the base of Power flow problem. It can be solved through Newton Raphson Method.Bus classification Four potentially unknown quantity are associated with each bus LOAD BUS - P & Q are specified / V & to be calculated.

GENERATOR PV BUS P & V are specified / Q & to be calculated.

GENERATOR PQ BUS P & Q are specified / V & to be calculated.

SLACK BUS V and are known quantity

Newton raphson power flow solution

NEWTON RAPHSON LOAD FLOW

Newton raphson algorithmFor load buses P and Q are specified, while voltage and phase angle are set to 1.00 pu and 0

For PV bus phase angle are set to zero.

For Load buses P and Q are calculated by equation 1 and equation 2 while P and Q are calculated using equation 4 and 5 For voltage controlled bus P is calculated using equation 1 and P is calculated using equation 4.

The jacobian can be calculated by differentiating equation 1 and 2 The phase angle and voltage V is updated after each interval.

The iterations is continued until P and Q becomes minimum or close to zeroFACTS IN POWER SYSTEM The Flexible AC Transmission System(FACTS) is a new technology which is based on power electronic devices that offers an opportunity to enhance controllability, stability and power transfer capability of an AC Transmission systems.

SOME BENEFITS OF FACTS DEVICES

Reduction of transmission and distribution investment cost. Increased System Security. Increased Reliability. Enhanced Power Transfer Capability. Overall enhancement of Power Quality of system.Facts controller FACTS controller are intended for steady state operation. FACTS controller can be distinguished as follows:-

Svc ( STATIC VAR COMPENSATOR )Composed of thyristor controlled reactor (TCR), thyristor switched capacitor (TSC) and harmonic filters connected in parallel to provide dynamic shunt compensation.Provides a dynamic voltage control to increase the transient stability, enhancing the damping power oscillations and improve the power flow control of the power systems.

THYRISTOR CONTROLLED SERIES COMPENSATOR It consists of three main components: Capacitor bank, bypass inductor and bidirectional thyristors SCR1 and SCR2.It offers a flexible adjustment with the ability to control the continuous line compensation.

STATIC SYNCHRONOUS SERIES CAPACITORBased on solid-state, voltage source converter is designed to generate the desired voltage magnitude independent of line current.

It consists of a converter, DC bus (storage unit) and a coupling transformer.

It can exchange both the real and reactive power in a transmission line.

Static synchronous compensatorIts designed is based on Voltage source converter (VSC) electronic device with Gate turn off thyristor and a dc capacitor coupled with step down transformer tied to a transmission line.

Improve the voltage stability of a power system by controlling the voltage in transmission and distribution systems.

Improves the damping power oscillation in transmission system.

Unified power flow controllerIt consists of two converters, one connected in series with the transmission line through a series inserted transformer and the other one connected in shunt with the transmission line through a shunt transformer.

It is designed by combining the series compensator (SSSC) and shunt compensator (STATCOM) coupled with a common DC capacitor.

It provides the ability to simultaneously control all the transmission parameters of power systems, i.e. voltage, impedance and phase angle.

INTERLINE POWER FLOW CONTROLLERIPFC consists of two series connected converters with two transmission lines.

It provides series reactive compensation in addition any converter can be controlled to supply active power to the common dc link from its own transmission line.

GENERALIZED POWER FLOW CONTROLLERIt is designed by combining three or more dc to ac converters working together extending the concepts of voltage and power flow control of the known two-converter UPFC controller to multi voltage and power flow control.

Can simultaneously control the power flow of several transmission lines.

Statcom modeling STATCOM will be represented as a synchronous voltage source with minimum & maximum limits.

The synchronous voltage source represents the fundamental Fourier series component of the switched voltage waveform at the AC converter terminal of the STATCOM.

The bus at which the STATCOM is connected is represented as a PV bus, which may change to a PQ bus in the event of limits being violated.

STATCOM is represented as a voltage source for the full range of operation, enabling a more robust voltage support mechanism.Power flow model

STATCOM can be represented as a voltage source , and the STATCOM bus is considered as PV bus.POWER FLOW MODEL Voltage at STATCOM is given by --

Complex Injected Power --

Considering STATCOM as PV bus , and using the above values following power flow equations are obtained -- Power flow modelThe Real and Reactive Power for STATCOM is --

The equations shown above are than incorporated in load flow equation of power flow study and calculation are then carried out .POWER FLOW MODEL

The Load flow formulation, is upgraded to incorporate for the STATCOM inserted in the Power system networks.Now this equation can be solved by Newton Raphson load flow in similar way as shown before.results STATCOM is incorporated at various locations of IEEE bus systems and then the system is subjected to Load flow study by Newton Raphson method to check its effect on

Effect on Bus Voltage

Effect on Reactive Power Generation of Slack Bus.

STATCOM injected Power

Source impedance is taken as 0.1 p.u ( Xvr = 0.1 p.u.) while the mismatch tolerance is taken as =1e-12 IEEE 5 BUS SYSTEM Bus 1 Slack bus

Bus 2 Voltage Controlled Bus

Bus 3,4,5 Load Bus

STATCOM is placed at bus 3

Source Voltage Magnitude , Vvr = 1.1000

Initial Voltage for Source Voltage Angle = -4.8379

STATCOM injected Power = 20.6 Mvar

Number of Iteration = 5

mtlab hyperlink\ieee5buswstatcom\ieee5bus.m

Bus voltage Voltage at bus 3 is increased 0.98 p.u. to 1.00 p.u

Voltage at Bus 4 is also improved.Real & reactive power flows Reactive Power generation at slack bus is reduced from 92 Mvar to 86 MVAR.

Effect on Real Power is negligible.Ieee 14 bus systemBus 1 Slack Bus

Generator Bus 2,3,6 & 8

Load Bus 2,3,4,5,6,7,9,10,11,12,13 & 14.

STATCOM Placed at bus 5 & 7.

STATCOM source Voltage magnitude Vvr 1 = .900 , Vvr 2 = .900

STATCOM source Voltage Magnitude vr1 = -8.6144 , vr2 = -13.2696

STATCOM injected Power = 62.11MVAR & 45.79 MVAR

Number of Iterations = 7

mtlab hyperlink\code14.m

Bus voltage Bus voltage profile is improved for the system.

Bus voltages at STATCOM placed Bus improved to 1 p.u. Real & reactive power flows Reactive Power absorbed at slack bus is reduced from 16 MVAR to 7 MVAR.

Effect on Real power is negligible.Ieee 30 bus systemBus 1 Slack Bus

Generator Buses 2,6,8,11 & 13.

27 Load Buses

STATCOM placed at buses 4, 7, 14 & 29

STATCOM source voltages Vvvr1 = 0.9000 Vvvr2 = 1.1000 Vvvr3 = 0.9000 Vvvr4 = 1.1000

Ieee 30 bus system STATCOM voltage angle vr1 = -9.5309 vr2 = -13.2026 vr3 = -16.6416 vr4 = -18.3403

STATCOM Injected Power Bus 4 = 46.38 MVAR Bus 7 = 1.61 MVAR Bus 14 = 2.33 MVAR Bus 29 = 6.90 MVAR

Number of iteration = 7

mtlab hyperlink\ieee30s.m

Bus voltage Bus voltage profile of the system is improved.

Bus voltages at all STATCOM placed bus is improved to 1 p.u.

Buses away from STATCOM buses are less affected . REAL & REACTIVE POWER FLOWS Reactive Power absorption by slack Bus is reduced from 13 MVAR to 8 MVAR.

Real Power of the system remains unaffected.conclusion The following conclusion can be made by the analysis done

The bus voltage at all the STATCOM placed buses becomes 1 p.u.

Overall voltage profile of the bus system is improved.

More reactive power is available to the Network.

Reactive Power generation at the slack bus is reduced.

Real power remains unaffected. Future scope The load flow study can be done on large interconnected power system network like IEEE 118 BUS systems or higher.

UPFC , IPFC and other FACTS controller can also be incorporated along with the STATCOM and their effect on the system can be studied.

Optimal location of STATCOM can be found out using Genetic Algorithm and fuzzy logic.

ReferencesN.G.Hingorani FACTS Technology and Opportunities, Flexible AC Transmission Systems (FACTS) - The Key to Increased Utilization of Power Systems),Digest No. 1994/05,12 January 1994, pp 4/1-410

Enrique Acha, Claudio R. Fuerte-Esquivel, Hugo Ambriz-Perez and Cesar Angeles-Camacho, FACTS Modeling and Simulation in Power Networks, John Wiley and sons limited, 2004.

Hadi Saadat , Power System Analysis, TATA McGRAW HILL,ISBN 0-07-048739-1, 2002.

S.D.Sundarsingh Jebaseelan and Dr. R. Raja Prabu, Performance of Thirty Bus System with and without STATCOM, International conference on Trends in Electrical, Electronics and Power Engineering (ICTEEP), vol.12, issue 4, July 2012, pp 340-344.

K R Padiyar and A.M.Kulkarni, FACTS-Flexible AC Transmission System-A status review, sadhna, vol.22, no.6, pp781-796, 1997.

A.Bhargave, V.Pant and B.Das , An Improved Power Flow Analysis Technique Using STATCOM, Power Electronics, Drives and Energy Systems, 2006. PEDES '06. International Conference, vol. 11, issue 3, December 2006, pp. 1-5.

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