Application of Synchrophasor Technology for Wide Area Measurement System

Application of Synchrophasor Technology for Wide

Area Measurement System

By

Lashkari Himanshu Dineshkumar

Enrolment No: - 110430707001

Guided by

Prof. Jaydeepsinh B. Sarvaiya

M.E. (Electrical Power System)

Assistant Professor

Electrical Engineering Department

A thesis Submitted to

Gujarat Technological University

In Partial Fulfilment of the Requirement for

The Degree of Master of Engineering

In Electrical Engineering

May-2014

Electrical Engineering Department

Shantilal Shah Engineering College, Bhavnagar

I

CERTIFICATE

This is to certify that research work embodied in this thesis entitled Application of

Synchrophasor Technology for Wide Area Measurement system was carried out by

Mr. Lashkari Himanshu Dineshkumar (110430707001) at Electrical Engineering

Department, Shantilal Shah Engineering College, Bhavnagar, for the partial

fulfillment of M.E. degree to be awarded by Gujarat Technological University. This

research work has been carried out under my supervision and is to my satisfaction of

department. The students work has been published for publication.

Date: / /

Place:

Guided By Principal

Prof. Jaydeepsinh B. Sarvaiya Dr. M. G. Bhatt

Seal of Institute

II

COMPLIANCE CERTIFICATE


Synchrophasor Technology for Wide Area Measurement System was carried out by

Mr. Lashkari Himanshu Dineshkumar (Enrollment No. 110430707001) at Shantilal

Shah Engineering College (043), Bhavnagar for partial fulfillment of Master of

Engineering degree to be awarded by Gujarat Technological University. He has

complied with the comments given by the Dissertation phase I as well as Mid

Semester Thesis Reviewer to my satisfaction.

Date: / /

Place:

Signature and Name of Student Signature and Name of Guide

PAPER PUBLICATION CERTIFICATE


Synchrophasor Technology for Wide Area Measurement System carried out by Mr.

Lashkari Himanshu Dineshkumar (Enrollment No. 110430707001) at Shantilal Shah

Engineering College (043), Bhavnagar for partial fulfillment of Master of Engineering

degree to be awarded by Gujarat Technological University, has published article

entitled Matlab Based Simulink Model of Phasor Measurement Unit and Optimal

Placement strategy for PMU Placement for publication by the INTERNATIONAL

JOURNAL FOR SCIENTIFIC RESEARCH & DEVELOPMENT in May 2014.

Date: / /

Place:

Signature and Name of Student Signature and Name of Guide

Signature and Name of Principal

III

THESIS APPROVAL

This is to certify that research work embodied in this entitled Application of

Synchrophasor Technology for Wide Area Measurement System was carried out by

Mr. Lashkari Himanshu Dineshkumar (110430707001) at Shantilal Shah Engineering

College (043) is approved for award of the degree of Electrical Engineering by

Gujarat Technological University.

Date: / /

Place:

Examiner(s) :-

_____________________ _____________________ _____________________

IV

DECLARATION OF ORIGINALITY

I hereby certify that I am the sole author of this thesis and that neither any part

of this thesis nor the whole of the thesis has been submitted for a degree to any other

University or Institution.

I certify that, to the best of my knowledge, my thesis does not infringe upon

anyones copyright nor violate any proprietary rights and that any ideas, techniques,

quotations, or any other material from the work of other people included in my thesis,

published or otherwise, are fully acknowledged in accordance with the standard

referencing practices. Furthermore, to the extent that I have included copyrighted

material that surpasses the bounds of fair dealing within the meaning of the Indian

Copyright Act, I certify that I have obtained a written permission from the copyright

owner(s) to include such material(s) in my thesis and have included copies of such

copyright clearances to my appendix.

I declare that this is a true copy of my thesis, including any final revisions, as

approved by my thesis review committee.

Date: / /

Place:

Sign. of Student:- :-

Name of Student :- Lashkari Himanshu Dineshkumar

Enrollment No. :- 110430707001

Signature of Supervisor :-

Name of Supervisor :- Prof. Jaydeepsinh B. Sarvaiya

Institute Code :- 043

V

ACKNOWLEDGEMENT

I sincerely express my deep sense of reverential gratitude to my guide Prof.

J. B. Sarvaiya, Assistant Professor, Department of Electrical Engineering, Shantilal

Shah Engineering College, Bhavnagar, for his valuable suggestions, constant

encouragement and unflinching co-operation throughout this work. I sincerely

thank for his exemplary guidance and encouragement. His trust and support inspired

me in the most important moments of making right decisions and I am glad to work

with him. I would like to thank faculties of Electrical Engineering at S.S.E.C.

I would also like to thank Dr. M. C. Chudasama, Head, Department of

Electrical Engineering, Shantilal Shah Engineering College, Bhavnagar.

I extend my sincere thanks to all respected faculties of Department of

Electrical Engineering, Shantilal Shah Engineering College, Bhavnagar for

providing me such an opportunity to do my project work.

I want to thank my family for always being there for me. Their love,

constant support and encouragement to pursue my goals made this thesis possible.

Special thanks to my colleague and friend Brijesh Solanki for useful advice as

well as help and support.

LASHKARI HIMANSHU DINESHKUMAR

VI

TABLE OF CONTENTS

Certificate

I

Compliance Certificate

II

Thesis Approval

III

Declaration of Originality

IV

Acknowledgement

V

Table of Contents

VI

List of Figures

VIII

Abstract

IX

Chapter 1 Introduction

1.1 Objective of Thesis

1

1.2 Scope of Work

2

1.3 Thesis Outline

3

Chapter 2 Literature Review

4

Chapter 3 Power System Monitoring

3.1 General

6

3.2 Smart Grid

7

3.3 Wide Area Measurement System

7

3.4 Overview of Synchronized Phasor Measurements

8

3.5 Phasor Measurement Unit

11

3.6 Communication Methods

13

3.7 Applications

14

3.8 Summary

15

Chapter 4

Fundamentals of Phasor Measurement Unit

4.1 Methods to obtain Synchronized Phasor Data

17

4.2 Architecture of PMU

19

4.3 PMU Implementation if India

20

VII

Chapter 5 Placement of Phasor Measurement Unit

5.1 General

22

5.2 Concepts of PMU Placement

23

5.3 Observability Rules for PMU

24

5.4 PMU Placement Algorithms

28

Chapter 6 Protection System with Phasor Measurements

6.1 Differential Protection of Transmission Line

32

Chapter 7 Simulation and Results

7.1 Matlab Simulink Model for PMU

36

7.2 Sampling Process for PMU

37

7.3 Matlab Modeling of DFT

38

7.4 Case Study of 5 bus System for PMU Output

38

7.5 Simulation Result

42

Chapter 8 Conclusion and Future Scope

43

References

44

Appendix A Nomenclature and Abbreviations

45

Appendix B Index

46

VIII

List of Figures

Figure 3.1 Phasor Representation

Figure 3.2 Phasor Representation with common reference

Figure 3.3 Phasor Representation with different Angles

Figure 3.4 Block diagram of PMU

Figure 3.5 A single line diagram presented for a Network

Figure 4.1 Sampling of waveform in discrete time

Figure 4.2 PMU Architecture

Figure 5.1 Example of the First Observability Rule

Figure 5.2 Example of Second Observability Rule

Figure 5.3 Example of Third Observability Rule

Figure 5.4 Depth First Algorithm for PMU Placement

Figure 5.5 Recursive N Security Algorithm

Figure 5.6 Recursive N-1 Spanning Algorithm

Figure 5.7 Algorithm for PMU Placement

Figure 6.1 Basic Current Differentials

Figure 6.2 Exact model of Transmission Line

Figure 7.1 Matlab model of PMU

Figure 7.2 Sample and Hold Circuit for PMU

Figure 7.3 Matlab discrete fourier transform

Figure 7.4 Case Study

Figure 7.5 Microsoft Excel Output of PMU

Figure 7.6 IEEE 14 Bus Network

Figure 7.7 Matlab Model for Protection system using Phasor Measurements

Figure 7.8 Output Waveform of case study

IX

Application of Synchrophasor Technology for Wide Area

Measurement System

Submitted By

Lashkari Himanshu Dineshkumar

Supervised By

Prof. Jaydeepsinh B. Sarvaiya

Assistant Professor in Electrical Engineering

Abstract

For the secure and reliable operation of the interconnected power system, it is

required to measure and monitor the system in real time. Conventional Supervisory

Control and Data Acquisition / Energy Management System (SCADA/EMS) obtain

the data at interval of 2-10 sec. This report gives an idea about synchronized Phasor

Measurement (SPM) based Wide Area Monitoring System (WAMS) using Phasor

Measurement Unit (PMU) placed at various locations in electrical power network.

They are synchronized by the Global Positioning System (GPS) satellites. High

precision time stamped data are obtained from PMUs at typical rates of 30 samples

per second. For improvements in power system control and protection by utilizing

real time synchronized phasor measurements is suggested. In this Dissertation work,

Objective of the work is to develop a Matlab based Simulink model of the Phasor

Measurement Unit. Phasor Data Concentrator for Data storage and a common

reference time data are also developed in Matlab.

To install optimal nos. of PMUs in power system network is an important task.

Various methods like Depth First, Recursive Security, Recursive N-l spanning

suggesting optimal placement of PMUs for complete observability of a power system

are reviewed. Steady state and single branch outages for PMU placement algorithms

are analysed on IEEE-14 bus test system.

Synchronized Phasor Measurements can be used for Power system protection. This

SPM makes our power system protection more accurate and faster. So, we have

develop a Matlab Simulink model of differential protection using Synchronized

Current Measurements.

Application of Synchrophasor Technology for Wide Area Measurement System

1

Chapter 1

Introduction

The deregulation of electrical power system had been initiated by United

Kingdom in the year of 1990 and then followed by other countries. Electricity

Act 2003 changes the whole power scenario of India by deregulation of

power system. In this open market different utilities install power plant at

various locations and feed generated power to nearest existing grid. Now

there is a challenge to maintain system availability and reliability. To

achieve that some important parameters like P, Q, V, f, b to be measured

in time synchronized manner and in real time. For those measurements

Phasor Measurement Units (PMU) should install at particular location so

it transmit important data to respective grid.

In recent years, power systems have been very difficult to manage as the load

demands increase and environment constraints restrict the transmission network.

Three main factors cause voltage instability and collapse. The first factor is

dramatically increasing load demands. The second factor is faults in the power

system. The last factor is increasing reactive power consumption.

Many solutions have been developed to avoid blackouts However, catastrophic

blackouts still happen on the transmission line systems in some countries. In the early

1980s, a new technology, which is called the Synchronized Phasor Measurement Unit,

was developed to address many power systems problems around the world. The

output of the synchronized phasor measurement unit is very accurate due to the

phasor measurement at different locations being exactly synchronized. Using data,

comparisons could be made between two quantities to determine the system

conditions. The advantages of synchronized phasor technology are increasing power

system reliability and providing easier disturbance analysis system protection.


2

1.1 Objective

The objective of this project is to develop a Matlab based Simulink model for the

Phasor Measurement Unit. Presently, EMS/SCADA system is in use for the

StateEstimation of the system. But it suffers from some serious disadvantages like

Non-accurate State Estimation, unsynchronized data with respect to time. So, prime

requirement of current scenario is to develop such a system, that can oversome this

disadvantages of current measurement system and which is capable to give accurate

time synchronized state estimation of various parameters.

Synchronized phasor measurements are becoming an important element of

wide area measurement systems used in advanced power system

monitoring, protection, and control applications. Phasor measurement

units (PMUs) are power system devices that provide synchronized

measurements of real- time phasors of voltages and currents. Synchronization

of voltage and current waveforms are achieved by same-time sampling using

timing signals from the Global Positioning System Satellite.

1.2 Scope of Work

The scope of work is to make Comparative study of existing SCADA

based power monitoring a n d Wide Area Monitoring System(WAMS).

To develop a Matlab based prototype model for Wide Area Measurement

System.

To implement WAMS, inst allat ion cost of PMU is ver y high, so

there is need to place the opt imal number o f PMUs. Hence

ana lys is o f d ifferent opt imizat ion methods on st andard IEEE

test s syst em to be carr ied out .


3

1.3 Thesis Outline

The work carried out during project has been organized in Six chapters.

The present chapter consists of present scenario of Indian Power System.

Objective and scope of work of the project work also described.

Chapter 2 describes the Literature Review for this Dissertation Work. In this

chapter various Reference Books & Papers are included which is very helpful to

carry out this work.

Chapter 3 presents existing power monitoring methods and its

limitations. It also coverers the basic concepts of synchronized phasor

measurement and its usefulness in current power system for better

performance.

Chapter 4 describes about Fundamentals of the PMU. The basic PMU

architecture and PMU and Synchrophasor initiative in India has been discussed

Chapter 5 denotes concept and placement rules of PMU in power system.

Various optimization methods for PMU placement discussed. It also concludes

the main findings of the work presented in this report and further area of work.

Chapter 6 presents basic concepts of Protection system with Phasor

Measurements. A differential Protection approach using the Synchronized Phasor

has been described.

Chapter 7 is the Simulation and Result for the Phasor Measurement Unit and its

Placement strategies. Developed Simulink model of PMU is also used for the

power system protection.


4

Chapter 2

Literature Review

Literature Review plays a very important role in the project. Literature survey consists

of book referred which gives fundamental knowledge of synchronized phasor

measurement and its applications. Papers were taken from IEEE conference

proceeding referred etc. IEEE standards for PMU and PDC are also referred.

[1] Phadke A. G., Thorp J.S. and De La Ree Jaime 1 This paper entitled

Synchronized Phasor Measurement Applications in Power Systems paper

provides a brief introduction to the PMU and wide-area measurement system

(WAMS) technology and discusses the uses of these measurements for improved

monitoring, protection, and control of power networks.

[2] Adamiak Mark, Premerlani William and Kasztenny Bodgan 2 This paper at

General Electrical Co. entitled Synchrophasors: Definition, Measurement, and

Application provides Basic Idea regarding Synchrophasor Definition, Phasor

Reporting and system architecture for the Technology.

[3] IEEE Std C37.118 for Synchrophasors for Power Systems 3 This Standard

defines the measurement, provides a method of quantifying the measurements and

quality test specifications. It also defines data transmission formats for real-time

data reporting.

[4] Dotta Daniel and Chow Joe H. 4 This paper entitled A MATLAB-based PMU

Simulator discusses the importance of PMU data for Power system operation. In

this paper the main computational algorithms involved in the phasor measurement

process are illustrated using a MATLAB based PMU simulator. This paper gives a

good understanding of the phasor measurement process.


5

[5] Mynam Mangapathirao V., Harikrishna Ala, and Singh Vivek 5 The Paper

entitled Synchrophasors Redefining SCADA Systems discusses the existing

SCADA system and the recently installed Wide Area Monitoring System

(WAMS) at the Power Grid Corporation of India Ltd (PGCIL) Northen Regional

Load Despatch Center (NRLDC). In case study two real system events are

analyzed for comparision of SCADA and Synchrophasor Measurements.

[6] Phadke A. F. and Nuqui R. F. 6 Phasor Measurement Unit Placement

Techniques for Complete and Incomplete Observability, This paper represents

the Optimal Placement Strategies for PMU Placement.

[7] Xu B., and Abur A. 7 Optimal Placement of Phasor Measurement Units for State

estimation The above PSERC report states about Optimal PMU Placement with

the State Estimation of the Power system Network.

[8] Federico M., 8 Documentation for PSAT The paper is the Documentation for

use of Power System Analysis Toolbox. It is a Matlab Toolbox which is very

helpful for the Implementation of various PMU Placement Technique.

[9] Phadke A. G. and Thorp J.S. 9 A book entitled Synchronized Phasor

Measurement and Their Applications gives information about fundamentals of

Phasor Measurement Techniques, Phasor Measurement Units. It enlightens about

synchronized phasor measurement applications in power system control and

protection schemes.


6

Chapter 3

Power System Monitoring

3.1 General

Electrical power system is widely distributed and complex network. For

protection, control, observe, billing purpose various electrical parameters are

measured and stored in a database. To transfer data from one point to other,

many techniques are available and applied according to importance of

measured data.

3.1.1 Traditional Power System Monitoring

The traditional approach to obtain a power system monitoring uses a SCADA

system to gather system data. SCADA systems obtain these data from

meters, transducers, IEDs, and similar devices. This process guarantees that

all the measurements are taken within a time window that is typically of a

few seconds long. The gathered data include status of breakers and switches,

real and reactive power flows, and voltage magnitudes. When the system is

in steady state, the measured quantities remain constant during the data-

gathering process. Thus, the time skew between measurements does not

introduce errors. The location of each measurement is chosen so that there are

enough data to estimate the voltage magnitudes and angles at all buses with

respect to an angle reference.

3.1.2 Limitations of Traditional Power System Monitoring

Conventional system monitors can fail under two circumstances: when the

system state is changing quickly and when critical data are missing. When the

power system state is changing quickly, measurements taken in a time

window of a few seconds are not consistent with each other. The

inconsistencies between any two analog measurements are proportional to

the time difference between the measurements and the rate at which the

states are changing. Additionally, rapid changes in system states are often


7

caused by changes in the topology of the system. When topology changes

are undetected or happen during SCADA data polling, the monitoring and

measurement estimation is likely to fail.

3.2 Smart Grid

A smart grid integrates advanced sensing technologies, control methods,

and integrated communications into the electricity grid. The smart grid

technologies and sources of data that could be utilized to improve fault

location methods by matching the field measurements to the simulated

values obtained using power system models. The smart grid brings both

benefits and design challenges to the utility, its customers, and the associated

technologists. The emerging smart grid system requires high speed sensing

of data from all the sensors on the system within few power cycles.

3.3 Wide Area Measurement System

A power system is continually subject to disturbances in the form of load

and generation changes, faults and equipment trippings. These

d i s t u r b a n c e s give rise to electromechanical transients like inter-machine

oscillations and system frequency changes. They can be observed in the

frequency measurements at various locations in the grid. To observe these

transients, a wide area frequency measurement setup is required. Wide

Area Measurement Systems(WAMS) are essentially based on new data

acquisition technology. Unlike c o n v e n t i o n a l control systems which use

Remote Terminal Units (RTUs) to acquire non synchronized RMS values

of currents and voltages.

WAMS system acquires GPS synchronized current, voltage and

frequency phasor data measured by PMUs at selected locations in the

power system. The measured quantities include both magnitudes and

phase angles, being time-synchronized via CPS receivers with an accuracy

of one microsecond. Wide area monitoring is a viable alternative as it

not only increases system security, but also allows the power system to

be run at its predefined security margin.


8

3.4 Overview of Synchronized Phasor Measurement

Phasor representation has been used to simplify the analysis of AC

circuits. The vector representation of the sinusoidal voltages and currents

is achieved by using the magnitude of the voltage and/or current and their

respective phase angles. Phasor measurements at important nodes help

system operators gain a dynamic view of the power system. Synchronized

phasor measurements resolved the issues of SCADA and have been used

mainly for power system model validation, post-event analysis, real-time

display, and opens a wide range of new applications.

What is a Phasor?

Phasor is a quantity with m a g n i t u d e and phase (with respect to a

reference) that is used to represents sinusoidal signal figure 3.1. Here the

phase or phase angle is the distance between the signal's sinusoidal peak

and a specified reference and is expressed using an angular measure.

Here, the reference is a fixed point in time (such as time = 0). The

phasor magnitude is related to the amplitude of the sinusoidal signal.

Consider a pure sinusoidal quantity given by

x(t) = Xm cos(t + ) (3.1 )

here being the frequency of the signal in radians per second, and being

the phase angle in radians. Xm is the peak amplitude of the signal. The root

mean square (RMS) value of the input signal is (Xm/2). Equation 3.1

can also be written as

x(t) == Re{ Xm ej(t+)

} == Re [{ej(t)

} Xmej

] (3.2)


9

Figure 3.1: Phasor Representation

The sinusoid of Equation 3.1 is represented by a complex number X known as

its phasor representation:

X(t) X == (Xm/2) ej

== (Xm/2) [cos + jsin ] (3.3)

What is Synchrophasor Technology?

-This synchronized sampling process of the different waveforms provides a com-

mon reference for the phasor calculation at all different locations.

The phase angle differences between two sets of phasor measurements is

independent of the reference.

Typically, one of the phasor measurements is chosen as the "reference" and

the difference between all the other phase angle measurements (also known as

the absolute phase angle) and this common "reference" angle is computed and

referred to as the relative phase angles with respect to the chosen reference.


10

Figure 3.2: Phesor Representation with Common Reference

Figure 3.3: Phesor Representation with Angle


11

3.4.1 Measurement of Synchrophasors

Synchrophasor measurements shall be tagged with the Universal Time

Constant (UTC) time corresponding to the time of measurement. This

shall consist of three numbers: a second of century (SOC) count, a fraction

of second count, and a time status value. The SOC count shall be a 4-

byte binary count in seconds from midnight (00:00) of January 1 s , 1970,

to the current second. Synchrophasor measurements shall be synchronized

to UTC time with accuracy sufficient to meet the accuracy requirements

of the standard IEEE C37.118. Time error o f 1 corresponds to a phase error

o f 0.022 for 60 Hz system and 0.018 for a 50 Hz system. As standard

permits phase error of 0.01 radian or 0.57 , this corresponds to a maximum

time error of 26 s for a 60 Hz system, and 31 s for a 50 Hz system.

3.5 Phasor Measurement Unit

The Phasor Measurement Unit (PMU) receive signals from Global

Positioning System (GPS) satellites, and provide synchronized measurements

from different locations to the desired destination, commonly known as

the phasor data concentrator (PDC). The measurement data can be used

for wide area monitoring; real time dynamics and stability monitoring;

dynamic system ratings; and improvements in state estimation, protection,

and control with help of Energy Management System (EMS). A state

estimator estimates the voltage magnitudes and phase angles at the

buses by using the available measurements in the form of power

injections, power flows, voltage magnitudes, or current through the

branches.

The f i r s t p r o t o t y p e of the PMU was developed and tested in Virginia

Tech in the early 1980s. The first commercial unit, the Macrodyne 1690

was developed in 1991. In the late 1990s, Bonneville Power Administration

(BPA) developed a wide area measurement system (WAMS), which

initiated the usage of PMUs for large-scale power systems.


12

Figure 3.4: Block Diagram of PMU

A PMU When placed at a bus, can provide a highly accurate measurements of the

voltage phasor at that bus, as well as the current phasors through the incident

transmission lines (depending on the available measurement channels).

Modern PMUs have some other features, like frequency measurement,

measurement of derived quantities like power components, power quality

related indicators.etc. and monitoring of the status of substation apparatus.

The analog signals are derived from the voltage and current transformer

secondaries, with appropriate anti-aliasing and surge filtering. The

microprocessor determines the positive sequence phasors, and the timing

message from the G PS, along with the sample number at the beginning

of a window, is assigned to the phasor as its identifying tag. The computed

string of phasors, one for each of the positive sequence measurements, is

assembled in a message stream to be communicated to a remote site

according to IEEE C37.118 standard. The messages are transmitted over a

dedicated communication line.


13

3.6 Communication Methods

For power system monitoring various communication links used both wired

and wire- less options.

Telephone lines: The main advantage of using phone lines is that

they are easy to set up and economical to use. These o f f e r data rates o f

up to about 56 kbps ( analog).

Fiber-optic cables: These offer data rates ranging from 50 million to 1

billion bits per second The advantages of using fiber-optics include its

immunity to RF and atmospheric interference, and the massive bandwidth

that it provides, which can be used by the utilities for other

telecommunication needs. The disadvantag of using fiber-optics is its

high initial investment.

Power lines: Power line communication (PLC) is a new technique

that is fast emerging and offering data rates in the range of 4 Mbps via

the electricity supply grid. Power line technology uses the medium and

low voltage electric supply grid for transmission of data and voice.

Microwave links: Point to point microwave links are also being used

by utilities to a great extent. Microwave links provide a better option

as compared to leased lines, since they are easy to set up and are highly

reliable. The main disadvantages of using microwave links are signal fading

and multipath propagation.

Satellites: Earth orbiting satellites can also be used to exchange data

between the PMUs and the monitoring stations. Remote substation SCADA

is one area where satellites have been used effectively. The disadvantages of

using a satellite include its high cost, narrow bandwidth.


14

3.7 Applications

Monitoring the State Variables

Synchronized phasor measurement unit can provide voltage and current magnitude

and phase in real time. The state variables of a network analysis are based on these

quantities, especially the phase angle, as angles are used to determine the voltage

stability and operation margin.

Figure 3.5: A single-line diagram presented for a network

The real power flow from the sending end can be calculated by

The reactive power is expressed by

Recall the equation of voltage regulation which is defined as

The relationship between can be also written by the line impedance, the phase angle

and the reactive power supplied to the line. Therefore, from these three equations

above, the new equation of voltage regulation can be written as

Voltage and current phasing verification

Improved state estimation


15

State estimation and dynamic monitoring

Traditional state estimation uses multiple asynchronous measurements, (such as active

and reactive power, voltage, current amplitude, etc.), obtained by iterative methods.

This process usually takes from a few seconds to minutes and generally only applies

to static state estimation. Through the application of synchronized phasor

measurement technology, the system node positive sequence voltage phasors and line

positive sequence current phasors can be directly measured. Various measurements

are taken by phasor measurement and combines traditional measurements. It can

improve the system state estimation speed and accuracy.

Substation voltage measurement

Synchrophasor- based protection

SCADA verification and backup

Wide-area frequency monitoring

Wide-area disturbance recording

Distributed generation control

Detecting out-of-step conditions

FACTS device operation and control

Voltage instability advance warning scheme

Angular stability advance warning scheme

Identifying inter-area power oscillations

3.8 Summary

In this chapter brief introduction of Synchronized Phasor Measurement

and its potential applications is given.


16

Chapter 4

Fundamentals of Phasor Measurement Unit

In this chapter we will consider certain practical implementation aspects of the PMUs

and the architecture of the data collection and management system necessary for

efficient utilization of the data provided by the PMUs. One of the most important

features of the PMU technology is that the measurements are time-stamped with high

precision at the source, so that the data transmission speed is no longer a critical

parameter in making use of this data. All PMU measurements with the same

timestamp are used to infer the state of the power system at the instant defined by the

time-stamp. It is clear that PMU data could arrive at a central location at different

times depending upon the propagation delays of the communication channel in use.

The time-tags associated with the phasor data provide an indexing tool which helps

create a coherent picture of the power system out of such data. The Global Positioning

System (GPS) has become the method of choice for providing the time-tags to the

PMU measurements, and will be described briefly in the following sections. Other

aspects of the overall PMU data collection system such as phasor data concentrators

(PDCs), communication systems, etc. will also be considered in this Chapter.

The industry standards which define file structures for compliant PMUs have been

very important to ensure interoperability of PMUs made by different manufacturers,

and will be considered in section.


17

4.1 Method to obtain the synchronized phasor data

Introduction to the Discrete Fourier Transform (DFT)

Discrete Fourier Transform

Digital computers are usually used to analysis the phasor data of a power system.

First, a discrete-time signal is obtained by sampling the original analog waveform. A

mathematic method which is called Discrete Fourier Transform is then applied to this

sampled data to obtain a sampled frequency waveform.

Figure sample a waveform in discrete time

Consider periodic discrete-time finite signal, taking N samples from 0 to 2, so that

the sampling time interval is 2 /N. The Fourier Transform can be expressed as

X is the complex number to express phasor ( usually expressed in rectangular form as

a + bj)

DFT has components at + and-. These components can be combined and divided

by the square root of 2 to get the RMS value.

-1.

The equation for the fundamental component can be rewritten as complex form as

following


18

1 Cycle Discrete Fourier Transform

DFT extracts the fundamental frequency component from input sinusoidal signal. It

will measure the Magnitude and Phase Angle of the signal.

1 cycle Discrete Fourier Transformer (DFT) = most commonly used phasor

estimation method.

Sampled data Xk used to calculate the phasor as,

Where,

N = number of Samples in 1-cycle of nominal

frequency

Sampling angle

The Nyquist criterion

If a signal contains frequency components greater than Hz, then sampling the signal at

cannot express the signal, an artefact called aliasing takes place. Therefore, any

analog signal must be bandwidth limited


19

4.2 Architecture of PMU

Fig 4.2 :- PMU architecture


20

4.3 Phasor Measurement Implementation in India

National and Regional Load Despatch Centres in India are being operated by Powem

Systems Operation Corporation(POSOCO), a wholly owned subsidiary of

POWERGRID, whereas State Load DespatchCentres are operated by respective State

utilities. They are equipped with State-of-the-Art SCADA/EMS system.

Telemetry from different sub-stations and power plants are being received at each

SLDC/RLDC and subsequently to NLDC which are being utilized in day to day

operations of the regional grid.

Synchronous Interconnection of regional grids forming large interconnected system

(for example formation of NEW grid ) and various changes undergoing in the Indian

power industry requires better situational awareness of the grid event and

visualization at the control center for real time system operation. Knowledge about

the angular separation between different nodes of a power system has always been of

great interest for power system operators. Phase angle measurement is commonly

used in auto synchronization of generating stations and check synchronization relays

used at substations for closing of lines as well as during three-phase auto-reclosing.

All these applications are at the local level.

Prior to the introduction of Phasor Measurement Units (PMUs) at control centre level

this analogue value is normally not considered as measurable in SCADA system and

hence does not form a part of the SCADA measurement. However SCADA

technology does provide an estimate of the relative phase angle difference (with

respect to a reference bus) through the State Estimator. The State estimator uses the

SCADA inputs (analogue and digital measurands) to estimate the system state viz.

node voltage and angle.

Information about phase angle difference between two different nodes in a power

system has also been calculated based on the real time power flow between the nodes,

bus voltages and network reactance using standard equation = sin-1 (P*X/V1*V2).

Angular information at control centre is also obtained by placing phase angle

transducer at strategic locations and interfacing it in existing SCADA system


21

However all the above methods of calculation of phase angle difference have

limitations due to resolution, data latency, updation time and data skewedness.

Update time in the SCADA system is considerably large (up to 10-15 seconds) for

visualizing and controlling the dynamics of power system. The real time angular

measurement in the power system avoids above uncertainties and can be relied on to

assess the transmission capability in real time which is very crucial in efficiently

operating the present electricity market mechanism.

PMUs are able to measure what was once immeasurable: phase difference at different

substations. A pilot project was implemented in Northern Region (NR) to assess the

potential of PMU/synchrophasor measurements. Experienced gained with this pilot

project is described in the following paragraph.


22

Chapter 5

Placement of Phasor Measurement Unit

5.1 General

Secure o p e r a t i o n of power systems requires close monitoring of the

system operating conditions. The measurements received from numerous

substations are used in control centers to provide an estimate for all metered

and un-metered electrical quantities e.g. bus voltage (V), frequency (f),

current (I), active power flow (P) reactive power (Q), load angle (J) and

network parameters of the power system. Until recently, the a v a i l a b l e

measurements were provided by SCADA, including active and reactive

power flows and injections and bus voltage magnitudes. The utilization

of global positioning system (GPS), in addition to sampled data processing

techniques, for computer relaying applications has led to the development

of PMUs [1]. Phasor measurement units are monitoring devices that

provide extremely accurate positive sequence time tagged measurements. A

PMU installed at a bus can make synchronized measurements of the voltage

phasor of the bus and the current phasors of some or all the branches

incident to the bus, assuming that the PMU has sufficient number of

channels. These phasor measurements are obtained from t h e P M U s

directly at t he locations, where these have been installed. Then applying

Kirchhoff's and Ohm's laws, the remaining variables can easily b e

ca lcu la t ed as pseudo measurements. The problem of network observability

has been studied by various researchers in the past. Two different approaches

used for solving this problem are based on numerical observability and

topological observability, which have their own advantages and disadvantages.

A wide range of such strategies can be cited from the Optimum PMU

Placement (OPP) literature, like Depth First Search (DFS), Minimum

Spanning Tree (MST), Simulated Annealing (SA), Tabu Search (TS),

Genetic Algorithms (GA). In the power system placement of PMU can be

studied by various methods considering complete system observability.


23

5.2 Concepts of PMU Placement

A PMU is able to measure the voltage phasor of the installed bus and

the current phasors of some or all the lines connected to that bus. The

following generalized rules can be used for PMU placement.

Rule 1: Assign one voltage measurement to a bus where a

PMU is placed, including one current measurement to each branch

connected to the bus itself.

Rule 2: Assign one voltage pseudo-measurement to each node

reached by an- other equipped with a PMU.

Rule 3: Assign one current pseudo-measurement to each branch

c o n n e c t i n g two buses where vo lt ag es are known. This

a l lo w s interconnecting observed zones.

Rule 4: Assign one current pseudo-measurement to each branch

where current can be indirectly calculated by the Kirchhoff

current law (KCL). This rule applies when the current balance

at a node is known.

The observability conditions that have to be met for selecting the

placement of PMU sets are

Condition 1: For PMU installed at a bus, the bus voltage

phasor and the current phasors of all incident branches are

known.

Condition 2: If one end voltage phasor and the current phasor of a

branch are known, then the voltage phasor at the other end of the

branch can be calculated.

Condition 3: If voltage phasors of both ends of a branch are

known, then the current phasor of this branch can be directly

obtained.


24

Condition 4: If there is a zero-injection bus without PMU and

the current phasors of the incident branches are all known but one,

then the current phasor of the unknown branch can be calculated

using KCL.

Condition 5: If the voltage phasor of a zero-injection bus is

unknown and the voltage phasors of all adjacent buses are known,

then the voltage phasor of the zero-injection bus can be obtained

through node voltage equations.

Condition 6: If the voltage phasors of a set of adjacent zero

injection buses are unknown, but the voltage phasors of all the

adjacent buses to that set are known, then the voltage phasors

of zero injection buses can be computed by node voltage

equations.

The me a s u r e me n t s obtained from Condition 1 are called direct

measurements. The measurements obtained from Conditions 2-3 are also

called pseudo-measurement. The measurements obtained from Conditions

4-6 are called extension-measurements.

5.3 Observability Rules for PMUs

Placing a PMU at every substation would certainly provide all the necessary real-time

Voltage magnitudes and angles for system observability; however this is redundant

due to an important attribute of PMUs. Provided that you know a buss voltage

magnitude and angle, all current phasors, and the connecting line parameters, then all

connecting bus voltages and angles can be calculated. By ohms law, if you know the

voltage magnitude and phase at Bus A, the voltage at Bus B would be the voltage at

bus A minus the voltage drop caused by the current traveling through the connecting

line. This sets up the first observability rule, that all buses connected to a directly

observable bus are observable themselves, as illustrated in Figure 5.1


25

Figure:- 5.1 Example of the First Observability Rule. Red values are already

known, blue values can be calculated.

VB = VA IAB(RAB + jXAB)

VC = VA IAC(RAC + jXAC)

VD = VA IDA(RAD + jXAD)

This significantly reduces the number of PMUs (and therefore cost) needed for

complete observability. PMUs are required to be on a minimum of 20-30% of buses to

achieve full system observability. Because of the ability of a PMU to observe

neighboring busses, PMU placement for full observability is very similar to the graph

theory topic of Domination.

There are also many special situations in which a bus can be calculated even if it is

not connected to a directly observable bus. The following general rules cover many of

these situations in which a bus does not have injection. If a bus without injection is

observed and all but one of its connecting buses is observed, then the unobserved bus

becomes observed.


26

Figure:- 5.2 Example of Second Observability Rule

VA = VC + IAC(RAC + jXAC)

IDA = VD - VA / (RAC + jXAC)

IAB = IDA IAC

VB = VA + IAB(RAB + jXAB)

An unobserved bus without injection connected only to observed buses is itself

observable.


27

Figure 5.3 Example of the Third Observability Rule

VA = VB + IAB(RAB + jXAB)

VA = VC + IAC(RAC + jXAC)

VA = VA IDA(RAD + jXAD)

0 = IDA - IAC - IAB

There could be other specific observability rules, but the three stated rules cover the

vast majority of situations and are adequately comprehensive and easy to implement

in placement algorithms. To recap:

1. All buses neighboring a bus with a PMU are observable themselves.

2. If all but one bus neighboring an observable bus without injection are

themselves observable, then all the neighboring buses are observable.

3. If all the buses neighboring a bus without injection are observable, then that

bus is also observable.


28

5.4 PMU Placement Algorithms

Various types of optimization techniques like Heuristic methods-depth first

and Meta- heuristic methods Recursive Security, Recursive N-1

Spanning,are discussed as per review paper.

5.4.1 Depth First Algorithm

This method uses rules from 1 to 3 (it does not consider p u r e transit nodes)

only. The first PMU is placed at the bus with the largest number of connected

branches. If there are more than one bus with such characteristic, one is randomly

chosen. PMU are placed with the same criterion, until the complete network

visibility is obtained as depicted in figure 5.4

Figure 5.4 Depth First Algorithm for PMU Placement


29

5.4.2 Recursive N Security Algorithm

This method is a modified depth first approach. The procedure can be

subdivided into three main steps as per figure 5.5

Step 1: Generation of N minimum spanning trees: Figure 3.2 depicts

the flowchart of the minimum spanning tree generation algorithm. The

algorithm is performed N times (N being the number of buses), using

each bus of the network as starting bus .

Step 2: Search of alternative patterns: The PMU sets obtained with the

step (1) are reprocessed as follows: one at a time, each PMU of each set is

replaced at the buses connected with the node where a PMU was originally

set, as depicted in figure3.2 PMU placements which lead to a complete

visibility are retained.

Step 3: Reducing PMU number in case of pure transit nodes: In this step, it is

verified if the network remains observable taking out one PMU at a time from

each set, as depicted in figme3.2. If the network does not present pure transit

nodes, the procedure ends at step (2). The placement sets which present the

minimum numbers of PMUs are finally selected.

5.4.3 Recursive N-l Spanning Algorithm

The rules for minimal PMU placement assume a fixed network topology and a

complete reliability of measurement devices. Simple criteria which yield a

complete visibility in case of one line outage at a time (N-l spanning) is based on

the following: A bus is said to be observable if at least one of the two following

conditions applies:

Step 1: A PMU is placed at the node.

Step 2: The node is connected at least to two nodes equipped with a PMU.

Step 2 is ignored, if the bus is connected to single-end line.

Figure 5.6 depicts the algorithms for obtaining the N-1 Spanning placement.


30

Figure 5.5 Recursive N Security Algorithm

Figure 5.6 Recursive N-1 Spanning Algorithm


31

Figure 5.7 Algorithm for PMU Placement

The Proposed Algorithm is for Optimal location of PMU placement from which, the

power system network is completely observable. This developed method uses the

Placement rules for PMU placement and this algorithm is applied to IEEE 14 bus test

system. The Optimum location of PMU from above method are as shown in Results.


32

Chapter 6

Protection System with Phasor Measurements

Synchronized phasor measurements have offered solutions to a number of

vexing protection problems. These include the protection of series compensated lines,

protection of multi terminal lines, and the inability to satisfactorily set out-of-step

relays. In many situations the reliable measurement of a remote voltage or current on

the same reference as local variables has made a substantial improvement in

protection functions possible. In some examples communication of such

measurements from one end of a protected line to the other is all that is required while

in others communication across large distances is necessary.

Phasor measurements are particularly effective in improving protection

functions which have relatively slow response times. For such protection functions,

the latency of remote measurements is not a significant issue. For example, back-up

protection functions of distance relays and protection functions concerned with

managing angular or voltage stability of networks can benefit from remote

measurements with propagation delays with latencies of up to several hundred

milliseconds. The next two sections will consider improved line protection using

phasor measurements from the remote ends of the line. The following section

involves adaptive protection in which the phasor measurements assist in making

adjustments automatically in various protection functions in order to make them more

attuned to prevailing system conditions.

6.1 Differential Protection of Transmission Line

Differential protection of buses, transformers, and generators is a well-

established protection principle that has no direct counterpart in protection of long

transmission lines. Pilot relays use communicated information from remote locations.

True differential protection was not possible before synchronized phasor

measurements. The advantages of differential protection are important for series

compensated lines and tapped lines. There are a number of forms of current


33

differentials for line protection. In the first form the currents are combined using a

communication channel and compared. In the second form the currents are sampled

and the samples communicated over a wide band channel, and in the third form

phasors are computed from the samples and the phasor values communicated

Fig 6.1 Basic Current Differential

The dashed dual slope shown in Fig. 6.1 is used for high-current conditions

where current transformer (CT) accuracy and saturation is more likely. Transmission

lines equipped with series compensation, flexible alternating current transmission

system (FACTS) devices, or multiterminal lines present protection problems which

call for differential protection. To date, such transmission line problems are solved

with differential-like schemes such as phase comparison. The easy availability of

synchronized measurements using Global Positioning System (GPS) technology and

the improvement in communication technology make it possible to consider true

differential protection of transmission lines and cables. Differential protection can be

based on computed phasors or on samples, although it can be argued that significant

shunt elements in the transmission line make phasors the preferred solution. In either


34

case it is necessary to synchronize the sampling and time-tag the result. Phasors can

be computed from fractional-cycle data windows as in impedance relaying, although

full-cycle windows offer better security.

If Ii is the current phasor at terminal i (reference direction is positive when the

current is flowing into the zone of protection), the differential currents may be defined

as

Id = Ii (6.1)

A single restraining current may be constructed by averaging the magnitudes

of all terminal currents or taking the maximum of all the terminal currents as the

restraint. Alternately, one restraining current for each pair of terminals may be

constructed in order to maintain uniform sensitivity when one of the terminals of a

multi terminal line is out of service. This is equivalent to the use of multiple restraints

for multi winding transformers. If a two-terminal line is modelled with the exact-

equivalent, then the phasor currents and voltages are shown in Fig.

Figure 6.2 Exact model of Transmission Line

The impedances Zc1 and Zc2 are the impedances of the possible series

capacitor networks or FACTS devices, Z and Ys are the exact- impedance and

admittance, respectively. If the relay measures I1, V1, I2, and V2, then the differential

currents Ix and Iy can be obtained from Eq. Under no-fault conditions using

Kirchhoffs current law Ix = Iy. When a fault occurs the 50-Hz exact- is no longer

valid because the currents and voltages are no longer pure fundamental frequency

signals. A percentage differential characteristic such as shown in Fig. 6.1 based on Ix


35

and Iy on a per-unit basis, with a modest slope, is capable of sensing faults within the

zone defined by the terminal where Ix and Iy are measured.

V3 = V1 I1Zc1 (6.2)

V4 = V2 I2 I2ZC2

IS1 = V3YS IS2 = V4YS

IX = I1 IS1 IY = I2 IS2 (6.3)

The preceding discussion is for lines of any length because of the exact- equivalent

but has the disadvantage of requiring voltage measurements. In an approximation to

the charging current is proposed which does not require voltage measurement. The

assumption is that each end uses data communicated from the other end to perform

the current differential calculation.

The best synchronization is obviously obtained with GPS. Pre fault load

currents can also be used for synchronizing. Data communication over a dedicated

fibre channel, while expensive, provides the best performance. A frequency shift

power line carrier, voice-grade channel operating at 64 kbps, can also be used. The

reliability of current differential schemes can be improved by adding redundant

channels.


36

Chapter 7

Simulation and Results

Matlab Simulation of WAMS Architecture

In this chapter Matlab Simulation of Prototype PMU is developed. In this chapter,

Simulink Models and their Results are shown.

7.1 Matlab based Simulink Model for Phasor Measurement Unit

Figure 7.1 Matlab model of PMU

In this model it is shown that how a PMU can be realized in Matlab. Three phase

Source is taken and V-I measurement from conventional CT & PT is done. Voltage

and Currents is given to the DFT. Output of DFT is Magnitude & Phase angle of the

input phasor. This output is Time Synchronized as we are making Time

Synchronizing with UTC. This output is stored in work space and also in PDC.


37

7.2 Sampling Process for PMU

Figure:- 7.2 Sample & Hold Ckt. For PMU

Sampling is very important to get the precise time stamping to the measurements.

Nyquist criteria is to be followed for the sampling. For 50 Hz power system your

sampling frequency should be minimum of fs 2f0. In our case we are Sampling

frequency is of 500 samples per second.


38

7.3 Matlab modeling of DFT

Figure:- 7.3 Matlab Discrete Fourier Transform

Discrete Fourier Transform Extracts the Fundamental frequency from the given

sinusoidal input. It also gives the Magnitude output and phase angle of the input

signal. Here Matlab modeling for DFT is done by the Fourier

TransformvMathematical Relation.

7.4 Case Study of 5 bus system for PMU output

Figure:- 7.4 Case study of 5 bus system for PMU output

In this case study a simple 5 bus system is considered. 5 PMU is placed at each bus.

PMU is calculating the magnitude and phasors with time synchronization.


39

Figure:- 7.5 Microsoft Excel Output of PMU

From above diagram it is quite clear that PMU measures the input phasors and Phasor

Data concentrator concentrates that data with common time reference frame.

7.5 Case Study for PMU Placement

The a lgor ithms discussed in previous chapter are applied to IEEE 14 bus

test system. Figure 7.8 represents its graph model. Results of all methods

are ga ined with h e l p o f Power S y s t e m Analysis Toolbox (PSAT) and

d e s c r i b e d as per T a b l e . The PMU heading in Table indicates minimum

PMU hardware required for complete system observability, and the results

indicates various PMU placement combinations possible for complete

observability with the no. of PMUs remained same. The head ing B u s

location points o ut t he bus numbers f o r PMU po s i t io n . Following a line

outage, N-1 method result PMU set list and network would remain still

observable.

For complete system observability the Recurs ive N Security algorithm

suggests minimum three PMUs i n s t e a d of six from Depth First algorithm,

hence i t would be beneficial in cost comparison. However R e c u r s iv e N-1

Spanning algorithm would be more preferable as it includes s i n g l e

outage o f system component.


40

Figure 7.6 IEEE 14 bus Network

Table I: PMU Placement Results of IEEE-14 Bus through Distinct

Algorithms IEEE 14 Bus Test System

Method No. of PMUs Set Bus Location

Depth First 06 01 1, 4, 6, 8, 10, 14

Recursive N Security 03 01 2, 6, 9

2,5,6,7,9,10,13,14

1,3,5,7,9,11,12,13

1,2,4,6,7,10,13,14

Recursive N-1 Spanning 08 10 2,3,5,7,9,10,11,12

2,3,5,7,9,11,12,13

1,2,4,6,7,10,13,14

2,3,5,7,9,11,12,13

2,3,5,7,9,11,12,14


41

2,3,5,6,7,9,11,13

1,2,4,6,7,10,12,14

Results from developed Method is as under:

Total No. of Possible Solutions for 14 bus Network = 214

=16384

Solutions with Complete Observability = 6181

Solutions with Minumum PMUs =

{2,6,7,9}{2,6,8,9}{2,7,10,13}{2,8,10,13}{2,7,11,13}

Differential Protection using Synchronized Phasor Measurements

Figure 7.7 Matlab model for Differential Protection system using Phasor

Measurements


42

Differential Protection is one of the most important protection for Power system

protection as well as protection of Major Electrical Equipments. By development of

Time synchronized measurements, the differential protection can be more accurate

precise and Faster.

Figure 7.8- Output Waveform of Case Study for Differential Protection

7.5 Simulation Result

This is an attempt to analyze three different algorithms discussed in

this chapter. By using basic Rules and Conditions for PMU placement, a

generalized Algorithm is also developed and also tested for 14 bus IEEE test

system.

Here three distinct PMU Placement algorithms are compared with the aim of

achieving complete observability of the power system in steady state

conditions. The outage of one of the line or equipment also analysed and the

results of IEEE 14 bus test system are discussed.

A Matlab model for use of PMU for Differential protection is developed and

results are as shown in Figure 7.8


43

Chapter 8

Conclusion:

From this dissertation work it can be concluded that Application of

Synchronized Phasor measurement Improves the current monitoring and

controlling SCADA sytem.

Matlab simulink model of Phasor Measurement Unit is developed. By that

precise Time stamped and Synchronized Voltage and Current measurements

are obtained. A model for Phasor Data concerntrator is developed in Matlab

and by that a Time stamped measurements of various PMUs are stored on

common reference time.

Various PMU Placement Algorithm are implemented with the Aim of

achieving complete observability of network. A Placement strategy based on

Binary Integer programming is developed and implemented for IEEE 14 bus

system.

PMU can be very useful in application of Power system protection. A Matlab

Simulink model of Differential protection using PMU is developed and by

applying Time stamped current samples; results are analysed it can be

concluded that PMU is able to Identify fault and generate trip signal using

Phase angle.

Future Scope:

This dissertation work can be further extended for various applications in

power system protection. Relay co-ordination using synchrophasor and

Adaptive power system protection scheme is the new area for which this

project work can be helpful.

State Estimation and Intelligent load shedding application is possible with

Time synchronized measurements.


44

References

Papers:

[1] Phadke A. G., Thorp J.S. and De La Ree Jaime, Synchronized Phasor

Measurement Applications in Power Systems, IEEE Transactions On Smart

Grid, Vol. 1, No. 1, June 2010

[2] Adamiak Mark, Premerlani William and Kasztenny Bodgan,

Synchrophasors: Definition, Measurement, and Application, General

Electric Co., Global Research

[3] IEEE Std C37.118-2005 for Synchrophasors for Power Systems.

[4] Dotta Daniel and Chow Joe H., A MATLAB-based PMU Simulator, IEEE

Fellow.

[5] Mynam Mangapathirao V., Harikrishna Ala, and Singh Vivek, The Paper

entitled Synchrophasors Redefining SCADA Systems, Schweitzer

Engineering Laboratories, Inc., 2011.

[6] Phadke A. F. and Nuqui R. F., Phasor Measurement Unit Placement

Techniques for Complete and Incomplete Observability, IEEE Transactions

On Power Delivery, Vol. 20, No. 4, October 2005 2381

[7] Xu B., and Abur A. Optimal Placement of Phasor Measurement Units for

State estimation PSERC Final Project report, 2005

[8] Federico M., Documentation for PSAT , version 2.1.6 (2010)

Books:

[9] Phadke A. G. and Thorp J.S., Synchronized Phasor Measurement and Their

Applications, Springer, USA, 2008

Websites:

[10] www.naspi.com Northen American Synchrophasor Initiative

[11] www.pserc.com Power System Engineering and Relaying Committee
http://www.naspi.com/http://www.pserc.com/


45

Appendix A

Abbreviation

EMS Energy Management System

GIS Geographical Information System

GPS Global Positioning System

IED Intelligent Electronic Device

OPP Optimal PMU Placement

PDC Phasor Data Concentrator

PMU Phasor Measurement Unit

RMS Root Means Square

RTU Remote Terminal Unit

SCADA Supervisory Control and Data

Acquisition

SPM Synchronized Phasor Measurement

WAMS Wide Area Measurement System

Nomenclature

Load Angle (radian)

Phase angle (radian)

Frequency (radian)

F Frequency (Hz)

I Current (Ampere)

P Active Power (KW)

Q Reactive Power (KVAr)

V Voltage


46

Appendix B

Index

Algorithm for PMU Placement, ........................................................ 31

Applications, ............................................................................ ........ 14

Architecture of PMU, .................. ........................................... ........ 19

Block Diagram of PMU, ...................................................... ........ 12

Case Study of 5 bus, .................... ........................................... ........ 38

Communication Methods, ......... ........................................... ........ 13

Depth First Algorithm, ............ ........................................... ........ 28

Differential Protection, ................ ........................................... ........ 32

Discrete Fourier Transform, ......... ........................................... ........ 17

IEEE 14 bus, ................................ ........................................... ........ 40

Introduction, ................................ ........................................... .......... 1

Literature Review, ....................... ........................................... .......... 4

Matlab model of PMU, ................ ........................................... ........ 36

Matlab modeling of DFT, ............ ........................................... ........ 38

Observability, .............................. ........................................... ........ 24

Phasor, ......................................... ........................................... .......... 8

Phasor Measurement Unit, ...... ........................................... ........ 11

Phasor Representation, ................ ........................................... .......... 9

PMU Placement, ..................... ........................................... ........ 23

PMU architecture, ........................ ........................................... ........ 19

Power System Monitoring, ....... ........................................... .......... 6

Recursive N Security Algorithm, ..................................... ........ 29

Recursive N-l Spanning Algorithm, ....................................... ........ 29

References, .................................. ........................................... ........ 44

Results, ........................................ ........................................... ........ 36

Sampling Process for PMU, ......... ........................................... ........ 37

Simulation, .................................. ........................................... ........ 36

Smart Grid, ............................... ........................................... .......... 7

Synchronized Phasor Measurement, .................................... .......... 8

Wide Area Measurement System, ...................................... .......... 7
Binder 1.pdf1title.pdf2.certificate.pdfBinder 2.pdf3.acknowledgement.pdf4.table of content and abstract.pdfBinder 3.pdf

Documents

Application of Synchrophasor Technology for Wide Area Measurement System