PSS/E Based Network Frequency Response Analysis Tool Yu (Terry) Tian, MSc student, tian7@ualberta.ca Nov. 06, 2013 Department of Electrical and Computer Engineering, University of Alberta Motivation Software Algorithm Resonance: Because of the existence of both inductive and Read PSSE Case File 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. Retrieve steady state bus voltage V(0) from PSS/E 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. Modify PSSE case for each frequency Passive Load Generator ππΊ β = π πΊ + πβππΊ Series Impedance Model Transformer ππ β = π π + πβππ Transformer tap ratio and phase shift in three sequence are also included in the model. π2 π + ππ = π − ππ πππππβ = π + πβπ CIGRE Model π 1 = π 2 /π Transmission Line π πππππ β = π 1 ππππππ β = 0.073βπ 1 PSSE Network Frequency Response Tool 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: ο ο ο ο Identify Resonance ο Equipment Sizing Filter Design ο Equipment Loading Assessment Verify Standards/Limits Compliance Harmonic Problem Troubleshooting ππππππβ PI Model π β = π + πβπ Shunt Element π΅ β =π΅×β πΊ β =πΊ Distributed Line Model π΅ β = π΅ × β πππππππ‘ππ£π π βπ’ππ‘ Long line effect is considered. π΅ β =π΅÷β ο Interact with PSSE directly ο Support up to 50000 buses ο User friendly interface Frequency Scan Harmonic Calculation Case File Positive-Sequence Impedance Zero-Sequence Impedance Driving Point Impedance Transfer Impedance Spectrum / Waveform Output Comply IEEE 519 Standard Capacitor Loading per IEEE 18 ππ − ππ(0) πππ = πΌπ ο Reliable validated result ο Highly customizable ο Easy install/uninstall ETAP CYME Our Tool ETAP case CYME case PSSE case √ √ √ × × √ √ √ √ × × √ √ √ √ × √ √ × √ √ Software Graphical User Interface (GUI) ππ − ππ(0) πππ = πΌπ 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: IEEE 14 Bus System Diagram 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 Switching Transient Simulation GUI Transfer impedance: Software Demo Frequency scan result at bus 13 Frequency Scan GUI ππππ’ππ‘ππ£π π βπ’ππ‘ 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: Software Features βπ 1 = π 6.7 − 0.74 π Frequency scan result at bus 13 Lower impedance at 19th harmonic, better than option 1