POWER SYSTEM STABILITY – TRANSIENT STABILITY STUDIES – Application of 3 - ∅ faults

Prepared by – Doula Isham Rashik, Mentor – Dr. Mounif Abdallah

ELECTRICAL AND ELECTRONICS ENGINEERING, HERIOT WATT UNIVERSITY DUBAI CAMPUS

• Study and analyze transient stability for one-machine and

multi-machine systems using appropriate techniques.

• Perform manual computations for one machine system.

• Develop MATLAB program for one machine system.

• Develop MATLAB program for IEEE 14 Bus system.

• Programs finally to be interfaced with GUI.

DESIGN, MODELLING AND METHODOLOGY

“Transient Stability” is one of the critical issues in power

systems which poses major challenge to power engineers. It

is the stability concerns maintaining synchronism of the

generators when subject to severe disturbance. 3 - ∅ fault is

the most severe disturbance among all. Hence transient

stability analysis for application of 3 - ∅ fault for one and

multi – machine systems is chosen as final year EEE project.

TEST SYSTEMS

• For one machine system, Equal Area Criterion or EAC

technique will be applied to find critical clearing angle.

• For 14 Bus system, to obtain load flow solution, Newton –

Raphson method will be used. To solve swing equations

powerful Runge – Kutta technique will be used and

critical clearing time will be obtained.

MATLAB programs will be developed followed by transforming

them into set of GUI tools using MATLAB GUIDE based on the

mentioned techniques.

∅

Figure 3: Development and methodology of EAC tool for one – machine system

EAC graph obtained followed by critical clearing angles 𝛿𝑐𝑟 at 3 different fault locations via both methods as follows that allows determination of

stability.

Figure 5: Case 1 - Fault at Sending end Figure 6: Case 2 – Fault at Middle of line Figure 7: Case 3 – Fault at Receiving end

Sending end of line (faulty line intact after fault clearance)

Middle of the line (faulty line isolated after fault clearance)

Receiving end of line (faulty line isolated after fault clearance)

Manual Computations

72.3320 49.10 44.210

Computations via EAC tool

72.3380 49.160 44.210

Table 1: Critical clearing angles obtained at different fault points

Figure 1: One – machine system

Figure 2: IEEE – 14 Bus system

∅

Figure 4: Development and methodology of multi – machine transient stability tool

For 3 - ∅ fault occurring near bus no. 7 at line 7 – 9, swing curves for PV bus

generators are obtained as follows.

At fault clearance time of 0.3s, the system remains stable. At 0.4s, the system

goes unstable. Keeping all other parameters constant and changing fault

clearance time for 0.01s increments, it is found system undergoes transition

from stable to unstable between times 0.35s and 0.36s as shown in figures 10

and 11. Hence 0.35s is the critical clearing time 𝑡𝑐𝑟.

Similarly, critical clearing times for different fault locations are obtained as

tabulated in table 3.

Bus near which fault occurs

From Bus To Bus Critical clearing time (s)

11 2 0.125

1 5 0.119

65 6 0.371

6 11 0.395

6 13 0.397

1312 13 System remains stable

13 14 0.561

Table 3: Critical clearing times obtained at different fault points

Dr. Mounif Abdallah, Dr. P.K. Soori, Dr. Mutasim Nour and Dr.

Senthil Muthukumarswamy

Figure 8: Swing curves at 0.3s Figure 9: Swing curves at 0.4s

• Preventive measures and emergency actions.

• Establishment of relays for automatic re-closure breakers.

• Train fresh graduate power system engineers as GUI provides more

interactive features rather than traditional learning methods.

• Expansion of power systems.

• For one – machine system in table 1, can be observed that there is almost

negligible difference between the critical clearing angles obtained via both

techniques at each of the fault locations.

• From figures 8, 9, 10 and 11 it can be observed that 4 swing curves are

generated, indicating stable and unstable for particular fault clearing times for

IEEE 14 Bus system. Also reduced y-bus matrices at all conditions was found

to be 5x5. Critical clearing times are found to have different values at different

fault locations from table 3.

• Hence can be concluded both EAC tool and multi - machine transient stability

tool package can be used for its suitable application purpose.

TECHNIQUES USED

OBJECTIVES

ACKNOWLEDGMENTS

ABSTRACT

RESULTS – ONE MACHINE SYSTEM

RESULTS – IEEE 14 BUS SYSTEM

APPLICATIONS

CONCLUSION

Design Graphical User Interface (GUI) applications that will

enable Transient Stability Analysis for one and multi –

machine systems for Application of 3 - ∅ faults at different

locations.

AIM

Short forms Abbreviations

A1 Accelerating power of rotating mass

A2 Decelerating power of rotating mass

Pe1 Electrical Power output before fault

Pe2 Electrical Power output during fault

Pe3 Electrical Power output after fault

Pm Input Mechanical Power

Table 2: Abbreviations used for EAC graph representation

Figure 10: Swing curves at 0.35s Figure 11: Swing curves at 0.36s