code no: rr320203 set no. 1 iii b.tech ii semester regular ...eeeqp\6rr320203... · time: 3 hours...

$: Code No: RR320203 Set No. 1 III B.Tech II Semester Regular ...EEEQP\6RR320203... · Time: 3 hours Max Marks: 80 Answer any FIVE Questions ... Describe the various blocks of IEEE Type-1$
Code No: RR320203 Set No. 1

III B.Tech II Semester Regular Examinations, Apr/May 2006MODELLING OF POWER SYSTEM COMPONENTS

(Electrical & Electronic Engineering)Time: 3 hours Max Marks: 80

Answer any FIVE QuestionsAll Questions carry equal marks

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1. For the network shown in figure 1, draw its graph and mark a tree. How manytrees this graph will have. Mark the basic cut sets and basic loops and form thebus incidence matrix A, Branch path incidence matrix K and also the basic loopincidence matrix. [3+5+8]

Figure 1:

2. (a) For the network shown below, draw its graph and mark also a tree. Givethe total number of edges (i.e. elements), nodes, buses and branches for thisgraph. Write also its nodal equations and determine the elements of YBus

matrix directly by inspection.

(b) For the same network, write the loop equations and hence determine the el-ements of Zloop matrix directly by inspection. Values shown are currents &admittances Figure 2 [12+4]

Figure 2:

3. Describe the procedure of modification of Zbus by adding mutually coupled branchfrom existing buses (p) and (k). [16]

4. (a) Write a detail note on tap-changing and regulating transformer.

(b) Explain the necessity of transformer modelling for power system studies. [10+6]

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Figure 3:

5. (a) For the power system network shown Figure 3 obtain bus incidence matrix inthree phase representation.

(b) Find the sequence impedance matrix of an element whose phase componentimpedance matrix is: [8+8]

[

zabcpq

]

=

j0.5 j0.2 j0.1j0.1 j0.7 j0.4j0.2 j0.3 j0.8

Derive the formula used.

6. (a) Clearly explain what you understand by static and dynamic characteristics ofa load element.

(b) Sketch the load characteristics of a typical [8+8]

i. lighting load

ii. heating load.

7. (a) Develop the mathematical model of hydraulic value actuator in speed govern-ing system.

(b) Two generators rated 200Mw and 400Mw are operating in parallel. The droopcharacteristics of their governors are 4% and 6% respectively from no-load tofull-load. Assuming that the generator are operating at 50Hz, how a load of500Mw be shared between them. [8+8]

8. (a) Explain the fundamental characteristics of an excitation system?

(b) What is an exciter? Why it is necessary for Synchronous Generator?

(c) Explain IEEE type-1 model of an excitation system and hence derive thetransfer function. [4+4+8]

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1. (a) Define the following terms with suitable example: Basic

i. tree

ii. branches

iii. links

iv. co-tree

v. loop

(b) Write the relation among the number of nodes, number of branches, numberof Links and number of elements.

(c) For the graph given in figure 1 below, draw the tree and the corresponding

co-tree. Choose a tree of your choice, and hence write the cutset schedule.

[5+2+9]

Figure 1:

2. Derive the expressions for Bus admittance and impedance matrices by singulartransformation. [16]


4. A four bus system comprises following line dataLine (1-2) —– R = 0.05 pu, X = 0.15 puLine (1-3) —– R = 0.10 pu, X = 0.30 puLine (2-3) —– R = 0.15 pu, X = 0.45 puLine (2-4) —– R = 0.10 pu, X = 0.30 puLine (3-4) —– R = 0.05 pu, X = 0.15 pu

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(a) Find Ybus assuming that the line (1-2) is not connected.

(b) What modifications need to be carried out in Ybus if the line (1-2) is con-nected. Write modified admittance matrix. [8+8]

5. (a) Explain the primitive network three phase representation of a component inadmittance form.

(b) For a rotating element, find the sequence impedance matrix from phase im-pedance matrix using symmetrical component transformation matrix.

(c) Find z012

pq given

zabcpq =

j0.4 j0.1 j0.1j0.2 j0.6 j0.2j0.3 j0.3 j0.8

[4+6+6]

6. Explain clearly how a synchronous generator connected through a reactance canbe represented by equation model for transient analysis, which takes saliency andchanges in the field flux linkages into account. Draw the relevant phasor diagram.

[16]

7. (a) Explain the turbine model and represent as a block diagram and obtain trans-fer function of the models.

(b) Explain the mathematical model of a speed governor and hence derive thetransfer function. [8+8]

8. Explain the functional blocks of Automatic voltage regulator. [16]

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1. (a) Define the following terms with suitable example:

i. Basic tree

ii. branches

iii. links

iv. co-tree

v. loop(b) Write the relation among the number of nodes, number of branches, number

of Links and number of elements.

(c) For the graph given in figure 1 below, draw the tree and the correspondingco-tree. Choose a tree of your choice, and hence write the cutest schedule.

[5+2+9]

Figure 1:

2. (a) For the network shown below, draw its graph and mark also a tree. Givethe total number of edges (i.e. elements), nodes, buses and branches for thisgraph. Write also its nodal equations and determine the elements of YBus

matrix directly by inspection.

(b) For the same network, write the loop equations and hence determine the el-ements of Zloop matrix directly by inspection. Values shown are currents &admittances Figure 2 [12+4]


4. (a) Two branches connected between buses 2-3 and 3-1 having impedances

equal to j0.25 pu are coupled through mutual impedance Zm = j0.15 pu. Find

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Figure 2:

the nodal admittance matrix for the mutually coupled branches and write thecorresponding nodal admittance equations.

(b) What is primitive admittance and impedance matrix. Bring out the signifi-cance of system admittance matrix. [8+8]

5. (a) For the power system network shown Figure 3 obtain bus incidence matrix inthree phase representation.

Figure 3:

(b) Find the sequence impedance matrix of an element whose phase componentimpedance matrix is: [8+8]

[

zabcpq

]

=

j0.5 j0.2 j0.1j0.1 j0.7 j0.4j0.2 j0.3 j0.8

Derive the formula used.

6. A synchronous generator is connected to an infinite bus through a transmissionline. Neglecting the resistances draw the phasor diagram and derive the

(a) Relation between active power and power angle.

(b) Relation between reactive power and power angle. [8+8]

7. (a) Develop the mathematical model of hydraulic value actuator in speed govern-ing system.

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(b) Two generators rated 200Mw and 400Mw are operating in parallel. The droopcharacteristics of their governors are 4% and 6% respectively from no-load tofull-load. Assuming that the generator are operating at 50Hz, how a load of500Mw be shared between them. [8+8]

8. Describe the various blocks of IEEE Type-1 excitation system and develop themathematical model of the system. [16]

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1. (a) For the power system network shown in figure 1 below, draw the

i. Oriented graph [4]

ii. Tree and co-tree of the corresponding graph also show the basic/1oopsand basic cut sets for the same. [8]

Figure 1:

(b) Hence write down the basic cut set incidence matrix. [4]

2. Derive the expressions for Bus admittance and impedance matrices by singulartransformation. [16]


4. (a) Explain why often use Bus admittance matrix rather Bus impedance matrixin the load flow studies.

(b) Figure 2 shows the singe line diagram of a simple 4-Bus system. Table givesthe line impedances identified by the busses on which these terminate. Theshunt admittances at all busses is assumed negligible.

i. Find YBus assuming the line shown dotted is not connected

ii. What modifications need to be carried out in YBus if the line shown dottedis connected. [16]

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Line Bus-to-Bus R,pu X,pu1-2 0.05 0.151-2 0.05 0.151-3 0.10 0.32-3 0.15 0.452-4 0.1 0.33-4 0.05 0.15

Figure 2:

5. Develop the expressions for formation of three phase ZBUS for the element whichis added between two existing buses in a partial network. [16]

6. (a) For basic types of loads at a bus, develop the mathematical models and rep-resent their characteristics.

(b) A 2 pole 50 Hz, Turbo generator has a rating of 60 MVA. The Rotor has a massmoment of inertia of 9000 Kgm2. Calculate its inertia constant in MJ/MVAand its angular momentum in MJ-sec/elec. degree. [10+6]

7. (a) Develop the mathematical model of primary and secondary Control Loops andderive the transfer functions of each block.

(b) Determine the primary Automatic load frequency control loop parameters forthe following system data:Total rated area capacity = 2000 MwNormal operating load = 1000 MwInertia constant = 5 sec.Regulation = 2.4 hz/ p.u. MwAssume load frequency depending is linear. [10+6]

8. Explain the functional blocks of Automatic voltage regulator. [16]

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code no: rr320203 set no. 1 iii b.tech ii semester regular ...eeeqp\6rr320203... · time: 3 hours...

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