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An application of modal analysis in electric power systems to study inter-area oscillations
KTH, School of Electrical Engineering (EES), Electric Power Systems.
2015 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

In order to make the electricity supply more reliable and with the development of

electricity trading, electric power systems have been steadily growing these last decades. The

interconnection of formerly isolated networks has resulted in very large and complex power

systems. The drawback of this evolution is that these very large systems are now more

vulnerable to stability issues like inter-area oscillations where one area oscillates against one

or many others. These instabilities may be particularly dangerous if they lead to a blackout

(North America, 2003) which is why stability analysis has to be performed so as to prevent

these phenomena. The modal analysis, which is a frequency domain approach, is a very

powerful tool to characterize the small signal stability of a power system and will be the one

presented in this report.

This report is the result of a master thesis project performed in September 2014 to

February 2015 at the Network Studies Department of the Power System & Transmission

Engineering Department of the EDF group. Over the years, EDF has developed a

considerable experience in the diagnostic of inter-area oscillations and the tuning of power

system stabilizers by taking repeating actions in electrical networks worldwide. The main task

of this report is to formalize this expertise and widen the services offer of the Network Studies

Department. Indeed as explained above the development of large electrical networks has

increased the need for dynamic stability studies with particular attention to inter-area

oscillations. The work done during this project was then organized to guarantee the durability

of this expertise and can be divided into two parts: the first one deals with the theory behind

modal analysis and how it can be applied to power systems to diagnose eventual stability

issues regarding inter-area oscillations; and a second part which tries to give a method to

follow to neutralize the impact of an eventual diagnosed inter-area oscillation. Then, of

course, a case study based on an actual network has been used to illustrate most of the theory

and finally, last but not least in the engineering scope, a sensitivity analysis has been

performed. It is actually very important to know which parameters have to be known

precisely and which one can be estimated with standard values because in such a study the

time required for the data collection can be unreasonably long.

It appears from this project that the modal analysis, with its frequency domain

approach, is a very convenient tool to characterize the dynamic evolution of a power system

around its operating point. It allows to clearly identify the role of each group and to gather

groups with the same behavior easily. However, the method used to eliminate the effect of

any undesired inter-area oscillation is not easy to implement on an actual power system as a

many things have to be taken into consideration if one want to avoid unwanted side effects

and it necessitates important precision in the data.

Place, publisher, year, edition, pages
2015. , 87 p.
EES Examensarbete / Master Thesis, XR-EE-EPS 2015:002
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-163404OAI: diva2:800004
Educational program
Master of Science in Engineering - Electrical Engineering
Available from: 2015-04-01 Created: 2015-04-01 Last updated: 2015-04-01Bibliographically approved

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