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Summary of "TCSC Controller

Design for Damping InterareaOscillations"

by Yan, Liu & McCalley

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1. What is the problem beingstudied?

FACTS controller design and locationfor damping interarea modes.

A TCSC application example isprovided.

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2. Is it an important problem?Why or why not?

Yes.

With deregulation and increased system

loading, interarea problems arebecoming more significant. FACTSdevices have a great deal of potential to

influence the system response in thistime frame.

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2. Continued

They also provide the unique advantagefrom the deregulation point of view, of

being located within the transmissionsystem (as opposed to a generationfacility).

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3. What are the main results?

Provides a method for ranking variousinput/output pairs for control of interarea

oscillations. Tie line flow was more effective an input

signal than the speed difference signal.

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3. Continued

Modal and functional sensitivitymethods are used to determine the

location and design of a TCSCcontroller. These methods, originallyapplied to PSS design, were adapted

for FACTS controller applications.

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4. What method is used toproduce the results?

Functional sensitivities or the residuemethod was used for determining

controller inputs and outputs andlocations.

Modal sensitivities are used to

determine the candidate lines.

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4. Continued - 2

Assume the transfer function betweenthe kth input and the jth output of a

system are given by Gjk(s). Then Gjk(s) = Sum[Rijk/(s - li)] (i = 1, 2,

3, ... n).

The residues (Rijk's) can determinedusing Rijk = Cj ti vi Bk .

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5. What are the assumptions inthe paper? Are they realistic?

In the design of the controller, thecontroller gain (K) is assumed to be

small.

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5. Continued

They also assumed that the system andcontrol loop is as in the figure below.

u(s)

1 .

1 + sT tcsc KH(s)

G sy(s)

+

+

Zline

Z

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5. Continued - 2

The form of H(s) is {sT/(1 + sT)}[(1 +sT1)/(1 + sT2)]

m where m is the number

of compensation stages At each stage the angle of each

compensation block should be less than60.

The assumptions seem to be fairlyrealistic.

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6. How sensitive are the resultsto the assumptions?

The authors don't comment or providemuch insight to this.

The application is tested for a range ofconditions to find the maximum transfercapabilities.

The "best" controller (the one using thetie-line flow input) did have the smallergain of the two.

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7. What did you learn from thispaper?

This paper verifies many of the ideasdiscussed in this class and shows thepower of linear analysis in designingcontrollers for large systems.

The results show the potential of theTCSC for improving system flexibilityand oscillations.

The better results for tie-line flow may ormay not indicate a general trend.

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8. Describe the similarities anddifferences of this paper?

This paper is aimed at the interareaoscillation problem and provides a fairly

simple scheme for designing a linearcontroller based on linear analysis.

It does not deal with the TCSC model

itself, or with nonlinear theory as manypapers do.

It is a well-written paper.