PSS/E Based Network Frequency

Response Analysis Tool Yu (Terry) Tian, MSc student, tian7@ualberta.ca

Department of Electrical and Computer Engineering, University of Alberta

Motivation Software Algorithm

Left figure shows IEEE 14 bus

system. A shunt capacitor bank

is to be installed at bus 13 to

support voltage and to improve

power factor. The following two

options are analyzed through a

frequency scan study at bus 13:

Software Features

Software Graphical User Interface (GUI)

Transformer

𝑍𝑇 ℎ = 𝑅𝑇 + 𝑗ℎ𝑋𝑇

Transformer tap ratio and phase

shift in three sequence are also

included in the model.

Transmission Line

PI Model

𝑍 ℎ = 𝑅 + 𝑗ℎ𝑋

𝐵 ℎ = 𝐵 × ℎ

Distributed Line Model

Long line effect is considered.

Passive Load

Series Impedance Model

CIGRE Model

Shunt Element

𝐺 ℎ = 𝐺

𝐵 ℎ = 𝐵 × ℎ 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑖𝑣𝑒 𝑠ℎ𝑢𝑛𝑡

𝐵 ℎ = 𝐵 ÷ ℎ 𝑖𝑛𝑑𝑢𝑐𝑡𝑖𝑣𝑒 𝑠ℎ𝑢𝑛𝑡

Generator

𝑍𝐺 ℎ = 𝑅𝐺 + 𝑗ℎ𝑋𝐺

𝑅 + 𝑗𝑋 =𝑉2

𝑃 − 𝑗𝑄

𝑍𝑙𝑜𝑎𝑑ℎ = 𝑅 + 𝑗ℎ𝑋

𝑅1 = 𝑉2/𝑃

𝑅𝑙𝑜𝑎𝑑𝑠ℎ = 𝑅1

𝑋𝑙𝑜𝑎𝑑𝑠ℎ = 0.073ℎ𝑅1

𝑋𝑙𝑜𝑎𝑑𝑝ℎ =ℎ𝑅1

6.7𝑄𝑃

− 0.74

Nov. 06, 2013

IEEE 14 Bus System Diagram

Frequency Scan GUI Switching Transient Simulation GUI

PSSE Network Frequency Response Tool

ETAP CYME Our Tool

Case File ETAP case CYME case PSSE case

Frequency Scan

Positive-Sequence Impedance √ √ √

Zero-Sequence Impedance × × √

Driving Point Impedance √ √ √

Transfer Impedance × × √

Harmonic Calculation

Spectrum / Waveform Output √ √ √

Comply IEEE 519 Standard × √ √

Capacitor Loading per IEEE 18 × √ √

A Python software package developed by PDS-Lab which

analyzes network frequency response on the selected PSS/E

case file. Since the PSS/E itself does not have harmonic analysis

functions, this software can be treated as an 'add-on' of PSS/E.

Typical applications of this software include:

Identify Resonance

Filter Design

Verify Standards/Limits Compliance

Harmonic Problem Troubleshooting

Equipment Sizing

Equipment Loading Assessment

Interact with PSSE directly

Support up to 50000 buses

User friendly interface

Reliable validated result

Highly customizable

Easy install/uninstall

Read PSSE Case File

Retrieve steady state bus voltage V(0) from PSS/E

Modify PSSE case for each frequency

Apply a fault at bus i, Bus voltages after the fault (Vi and Vj), and fault

current at bus i (Ii) are retrieved from PSS/E fault analysis result.

Driving point impedance: Transfer impedance:

𝑍𝑖𝑖 =

𝑉𝑖 − 𝑉𝑖(0)

𝐼𝑖 𝑍𝑖𝑗 =

𝑉𝑗 − 𝑉𝑗(0)

𝐼𝑖

Option 1 Option 2

Add 2 Mvar capacitor

bank at bus 13

Add 1.8 Mvar capacitor

bank at bus 13

Very high impedance at 19th

harmonic, not good

Lower impedance at 19th harmonic,

better than option 1

Software Demo

Frequency scan result at bus 13 Frequency scan result at bus 13

Resonance: Because of the existence of both inductive and

capacitive components in the system, at certain frequencies,

resonance conditions might occur at some buses. If the

resonance occurs at a bus where a harmonic current is injected

into the system, an overvoltage will be observed.

Frequency Scan: A frequency scan is a plot of the driving-point

/ transfer impedance at a system bus versus frequency. The bus

of interest is one where a harmonic source exists. The frequency

scan is a very effective tool to detect resonances which appear as

peaks (parallel resonance) and valleys (series resonance) in the

plot of impedance magnitude vs. frequency.

One of the most common ways to obtain the harmonic impedance

is by using EMTP software. This requires a significant manual

labour to collect a huge amount of information and to model a

usually large interconnected network. Hence it is desirable to

have a software that can run frequency scan directly on a PSSE

case file, which stores all the system information and is well

maintained by utility companies.