power systems/ PSCAD/EMTDC/MATLAB/POWER LAB

ECE 43200/53201 Power Systems Fall 2020

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Power-Flow Problem Design Project 1

A final (Word document) written report should be submitted by Design Project due date: TBA

For the nine-bus power system shown in Fig.1, comprising three-generators, three-transformers, six-

transmission lines, and four-loads, consider the following design requirements.

Design Input Data

A. Bus Input Data

Consider Sbase= 100 MVA, Vbase = 16.5 kV at bus 1, Vbase = 18 kV at bus 8, Vbase = 13.8 kV at bus 9.

The line-to-line voltages are 230 kV base, 60 Hz at busses 2 through 7.

Bus 1 to which a generator is connected is the slack bus. Buses 8 and 9, to which generators (and

load) are connected, are voltage-controlled (or PV buses). Buses 2 through 7are load (or PQ) buses.

The Table 1 summarizes the power-flow input data and unknowns. You are asked to complete the

last column “Unknowns”.

Table 1 Bus input data and unknowns

Bus Type V

pu

𝜹 [°]

𝑷𝒈

pu

𝑸𝒈

pu

𝑸𝒈𝒎𝒂𝒙

pu

𝑸𝒈𝒎𝒊𝒏

pu

𝑷𝒅 pu

𝑸𝒅 pu

Unknowns

1 Slack 1.0 0.0 - - - - 0 0

2 Load - - 0 0 - - 0 0

3 Load - - 0 0 - - 1.25 0.5

4 Load - - 0 0 - - 0.9 0.3

5 Load - - 0 0 - - 0 0

6 Load - - 0 0 - - 1.0 0.35

7 Load - - 0 0 - - 0 0

8 Constant voltage 1.025 - 1.63 - 99.0 -99.0 0 0

9 Constant voltage 1.025 - 0.85 - 99.0 -99.0 0.8 0.25

B. Transformer Input Data

The transformer data summarized in Table 2 include per-unit winding impedances and exciting branch

admittances, and the maximum MVA ratings.

Table 2 Transformer input data

Bus-to-Bus R

pu

𝑿 pu

𝑮𝒄 pu

𝑩𝒎 pu

Maximum MVA pu

1-2 0.0 0.05760 0.0 0.0

5-8 0.0 0.06250 0.0 0.0

7-9 0.0 0.05860 0.0 0.0

ECE 43200/53201 Power Systems Fall 2020

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Fig.1 Single-line diagram of the power system

C. 230 kV Transmission Lines Input Data

The specified data for all transmission lines (ask your instructor) are

▪ Tower data: height of all conductors, spacing between phases, and the lines of the transmission system are transposed.

▪ Conductor Data: conductor name, radius and DC resistance, sag of all conductors, two bundle conductors.

▪ Ground Wires Data: ground wires name, radius and DC resistance, sag of all ground wires, spacing between ground wires, height of ground wires above conductors.

The line data include a maximum 12.0 per-unit MVA rating, for all six lines.

ECE 43200/53201 Power Systems Fall 2020

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Do the following for the power system design project:

I. Determine the actual values of the resistance, inductance, and capacitance of each transmission line using PSCAD/EMTDC. Then, calculate the per-unit (pu) line parameters (R, X, G, and B),

present the results in a table format, and use them to determine the series impedance and shunt

admittance of the lines’ Π (pi) models.

II. Determine the bus admittance matrix YBUS, calculate the power flow on the buses and transmission lines, and solve the network for the unknown voltage magnitudes and phase angles

using PowerWorld.

III. Insert a second line between bus 3 and bus 4, with your own new design line parameters. Determine the new line's effect on V4, the line loadings, and on the total real power losses.

IV. Determine the lowest per-unit voltage and the maximum line/transformer loading both for the initial case and for the case with the line from bus 7 to bus 4 out of service.

V. Determine the acceptable generation range at bus 8, keeping each line and transformer loaded at or below 100% of its MVA limit, and write your comments in the report.

VI. Determine the effect of adding a 200 MVAR shunt capacitor bank at bus 6 on the power system in Fig.1 and write your comments in the report. Find the MVAR rating of the shunt capacitor

bank that establishes V6 at 1.0 pu.

VII. Open one of the transformers and open one of the transmission lines. This results in overloading the other transformers. Re-dispatch the generators in order to remove the overload.

VIII. The transformer between busses 1 and 2 is now a tap-changing transformer with a tap range between 0.9 and 1.1, a step size of 0.00625, and the tap is on the high voltage side of the

transformer. As the tap is varied between 0.975 and 1.1, make your comments about the variation

in the reactive power output of generator 1, voltages V2 and V4, and the total real power losses.

Extracredit (10%): Use MATLAB to confirm YBUS, the Jacobian matrix for the power system, and apply

Newton-Raphson method to find the power flow solution.