Power System Dynamics Group

Research Projects

Enhancement of the Performance of Large Interconnected Power Systems

This three year research and development project, which is being funded by seven Australian power companies, continues work in this area which began in the School over a decade ago. A key feature of the project is that the results of our research are made available to the power industry participants through the provison of training and production-quality analysis and design software.
Dr. Mike Gibbard, Mr. David Vowles, Mr. Tyson Ritter

Determination of power system limits

The PSDG is developing tools, in collaboration with ElectraNet, to automatically search for the secure power-transfer limits on the flow in selected transmission elements, such as transmission lines, following each of a user-specified set of contingencies. The limits on power-flows may be due to (i) violation of the thermal-ratings of equipment; (ii) long-term voltage-instability; (iii) inadequate short-term voltage-performance; or (iv) short-term rotor-angle instability.
Mr. Tyson Ritter, Mr. David Vowles, Dr. Mike Gibbard and ElectraNet staff.

Projects undertaken by post graduate students under the supervision of Dr. Rastko Zivanovic are listed below.

Commercial Software

Mudpack

Mudpack is a comprehensive set of interactive software tools for:

analysing the small-signal stability and damping performance of multi-machine power systems, and
the coordinated design of power system stabilizers (PSSs) and stabilizers for FACTS devices (FDSs)

Mudpack and the associated stabilizer design methods are used by several Australian power companies.
A demonstration version of Mudpack is available for a nominal fee.
Dr. Mike Gibbard, Mr. David Vowles

Task Force/Working Group Activities

IEEE Benchmark Systems for Stability Controls Task Force

The PSDG has developed and contributed to the task force a test system which can be used as a test bed for the small-signal analysis and design of power system stabilisers (PSSs) and other controllers in a multi-machine power system.

IEEE Task Force on the Inclusion of Higher Order Terms for Small Signal (Modal) Analysis

The PSDG contributed to the above IEEE task force which was chaired by Juan Sanchez-Gasca. The work of the task force is summarized in the following paper:
Sanchez-Gasca J.J., Vittal, V., Gibbard, M.J., Messina, A.R., Vowles, D.J., Liu, S. and Annakkage, U.D., “Inclusion of Higher Order Terms for Small Signal (Modal) Analysis: Committee Report – Task Force on Assessing the need to include higher order terms for small signal (Modal) analysis”, IEEE Trans on Power Systems, Vol. 20, Num. 4, June 2005, pp. 1886-1904.

Consulting Activities

The PSDG is actively involved in consulting work with the power supply industry. Recent projects have involved:

Assessment of modal-estimation techniques which are based on the analysis of the ambient fluctuations in certain power-system variables.
Assessment of the impact of wind generation on the damping performance of power systems.
Development of a small-signal model for the Basslink HVDC interconnection between Tasmania and Victoria, Australia.
Assessment of the impact of Basslink on the damping performance of the mainland and Tasmanian power systems.
Design of a voltage-control system for a wind-farm connected to a very weak grid and the associated analysis and assessment of commissioning test results.
Development of a generic suite of small-signal models of wind farms.
Assessment of the performance of large-disturbance wind farm models.
Tuning of power-system-stabilizers and the analysis and assessment of commissioning test results.
Provision of training in power-system small-signal stability analysis and control to industry engineers.

Research Personnel

Dr. Michael Gibbard, Honorary Visiting Research Fellow
Dr. Rastko Zivanovic
Mr. David Vowles
Mr. Tyson Ritter

Post Graduate Students

Hoong Ooi, PhD topic: Sensitivity Analysis of Transmission Line Fault Location, Supervisor: Dr. Zivanovic
The location of transmission line faults on the basis of recorded voltages and currents is influenced by the transmission line model and its parameters, signal processing hardware & software, protection setting parameters and system factors reflected in voltage and current inputs. All these factors are subject to many sources of uncertainty including measurement and signal processing errors, setting errors, as well as absence of information and incomplete modelling of a system under fault conditions. This imposes a limit on our confidence in the fault location result. A complete practical fault location tool has to provide an estimate of the confidence in the result, possibly assessing the uncertainties associated with the influencing factors. In this research we apply a novel global sensitivity analysis technique to determine factors that mostly contribute to the fault locator output variability. Interactions between factors can be also determined, as well as regions in the space of input factors for which the result variation is maximum. In practice, such analysis can help in selecting the optimal fault locator for a specific application and also can help in the calibration process.
Mustarum Musaruddin, PhD topic: Automated Fault Analysis in Power Systems via Application Service Provider, Supervisor: Dr. Zivanovic
The analysis of faults and disturbances has been and will continue to be a fundamental foundation for a secure and reliable electrical power supply. The introduction of digital recording technology has opened a new dimension in both the quantity and quality of fault and disturbance data acquisition. Today the challenge is to automatically transform this large mass of data to useful knowledge in order to allow engineering and operational personnel to implement corrective or preventive action in a timely manner. The automated analysis system proposed to be developed in this PhD project would automatically perform the mathematical analysis of all (presently known) patterns of incorrect behaviour (disturbances and faults) issue a short message would be provided to operating personnel summarizing the required information and knowledge regarding the faults and the corrective measures. The automated analysis system will be developed as an online internet application based on Application Service Provider (ASP).
Hui-Min Tan, PhD topic: Transient Stability Sensitivity Analysis, Supervisor: Dr. Zivanovic
Transient stability assessment and control is more difficult in the current deregulated environment than before. This is due to the frequently changing generation/load patterns and network topology during normal power system operations. The competitive market, increasing system load and limited transmission capacity means the power system will need to operate closer to security margins for longer periods of time than was previously the case. Therefore, fast and accurate online determination of transient- stability margins will be required, together with clear guidance for operational personnel on how to most effectively steer the system from an insecure to secure state. Fast acting stability controls may be required to extend the secure operational limits of the system. This research work will investigate some improvements of the conventional off-line time- domain transient stability tools used to design stability control schemes for real-time operation. In the first phase the research will focus on power system modelling for transient stability studies. The selected models will be used to formulate the complete model of a power system in the form of combined non-linear differential and algebraic equations. Time-domain solution techniques will be applied to calculate the system response for different operational conditions and different values of selected parameters. In the second stage a sensitivity analysis technique will be applied to study the influence of various parameters and operational conditions on the transient stability margin. In the final stage we will demonstrate the application of the sensitivity analysis techniques to design a stabilizing controller to enhance the transient- stability of the power system. Some of the technniqes developed may also have the potential to be applied in the online assessment of transient- stability margins.
Chen Shuo, MSc topic: Broken Bar Detection using High-Resolution Spectral Analysis, Supervisor: Dr. Zivanovic
Spectral analysis of current or flux signals recorded during operation of an induction motor can be used to detect broken bar faults as well as estimate the number of broken bars in the rotor. In the conventional approach based on the Fast Fourier Transform (FFT) spectral analysis very long data windows with stationary motor load is required to separate the fundamental frequency (50Hz) from the fault (broken bar) frequencies. As the load decreases the fault frquency approaches the fundamental frequency and discrimination requires the data window to be enlarged if the FFT approach is used. The goal of this research is to make accurate broken bar detection and estimation using short data window even for the case of lightly loaded induction motor. It is envisaged that high-resolution parametric spectral estimation techniques can replace the FFT based method and provide improved accuracy for short data windows. Such technique will have high value in the practical cases when machine load is slowly-changing in time.