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Power and energy systems research has long been a strength of the School of Information Technology and Electrical Engineering.  The strong research output has continued in recent years.  Twelve PhD’s and four Masters Research degrees have been completed in the last 5 years.  Currently there are a further 22 postgraduate students pursuing research higher degrees in different aspects of power and energy systems engineering. The productiveness of the group’s research activities can be attributed, in part, to the close links and generous support provided by the group’s industrial and academic research partners.  The group has obtained significant financial support from both the Australian Research Council, and national and international research partners.  This strong focus on collaborative research is clearly shown in the following description of the key research projects in which the group has participated in or initiated within the last fours years.

Key Research projects

Innovation in Power System Asset Management

The project entails developing distributed, internet connected equipment, services and a business model to help the power industry deliver electrical power more reliably. This project will develop a commercial system for transformer and other critical asset condition monitoring and reporting. This project will complete the research and development of equipment and techniques that will underpin a commercial service to the global power industry.

Funding	The University of Queensland VC-strategic funding Scheme, 2006-08
Project Partners	University of Queensland
Chief Investigator	Prof Tapan Saha,
Research Fellow & other staff	Dr Hui Ma, Mr Ian Greg and Dr Andrew Thomas
Postgraduate Students	Jing Haur Yew (PhD thesis in progress)

 

 

Publications:

1. T. K. Saha, M. K. Pradhan, and J. H. Yew, “Optimal Time Selection for the Polarisation and Depolarisation Current Measurement for Power Transformer Insulation Diagnosis”, Paper accepted for the Proceedings of the IEEE Power Engineering Society General Meeting, June 24 - 28, 2007, Tampa, FL USA.

 

2. J H Yew, T K Saha, A J Thomas, “Impact of Temperature on the Frequency Domain Dielectric Spectroscopy for the Diagnosis of Power Transformer Insulation”, Proceedings of the IEEE Power Engineering Society General Meeting, Montreal, Canada, 18-22 June 2006.

3. Deriving an Equivalent Circuit of Transformer Insulation for Understanding the Dielectric response Measurements”,  IEEE Transactions on Power Delivery, Vol. 20, No. 1, pp. 149-157, January 2005.
4. Saha, T. K., Purkait, P, “Investigation of polarization and depolarization
   current measurements for the assessment of oil-paper insulation of aged transformers”, IEEE Transactions on Dielectrics and Electrical Insulation, Volume: 11, Issue: 1, Feb. 2004, Pages: 144 – 154
5. Saha, T.K., Purkait, P., “Investigation of an Expert System for Condition Assessment of transformer insulation Based on Dielectric response measurements”, IEEE Transactions on Power Delivery, Vol. 19, No. 3, July 2004, pp. 1127-1134.

 

Control methodologies of Distributed Generation for enhanced network stability and control 

 

The project proposed here addresses the key issues related to the integration of Distributed Generation centrally controlled in the National Electricity Market (NEM). It is expected that increasing amounts of new technologies in the form of distributed generations will be introduced in electrical power systems in the coming years. The emphasis on power generation from renewable sources leads to the development and se of technologies, such as solar panels, wind turbines and wave energy power plants. DG units can be connected closer to customers and hence transmission and distribution costs can be significantly reduced. The latest technology has made available plants with high efficiency and ranging in capacity from l0kW to 15MW, in particular wind farms. The liberalization of the electricity market contributes to creating opportunities for new utilities in the power generation sector;

 

As long as the penetration level of these new technologies in power systems is still low and they only cover a small fraction of the system load, they have little impact on the dynamic behaviour of a power system. Therefore, in power system long-term dynamics and transient stability studies, they are normally considered as negative load and their intrinsic dynamics are not taken into account. However, if the amount of new generation technology introduced in a power system becomes substantial, it will significantly influence the overall behaviour of the system. Penetration level (MW and voltage), location and proper model of the distributed generation will be important factors in the analysis of dynamic behaviour of power system. The goal of the research would be to investigate the impacts of DG on power system transient, small signal, and long term stability.

 

Funding	CSIRO, Intelligent Grid- Energy Transformed Flagship 2007-10
Project Partners	CSIRO, UQ
Chief Investigators	Prof. Tapan Saha, A/Prof. Zhao Dong,
Research Fellow	To be recruited
Postgraduate Student	To be recruited

Condition Assessment of Medium-Voltage XLPE-Insulated Cables Degraded by Water Treeing

In Australia degraded underground XLPE cables are causing disruption of electricity supplies and high community costs. There is no reliable non-invasive technique for prediction of cable condition to optimise cable replacement and refurbishment. In this project a large-scale experiment is in progress on 22 kV cables to ascertain the effectiveness of a new cable refurbishment technology. New techniques for assessment of cable condition will be developed using unique data from the ageing experiment and computer models of fundamental phenomena. Successful conclusions from this project will save the industry partner and other electricity distribution companies tens of millions of dollars.

Funding	Australian Research Council Linkage Grant 2004-07
Project Partners	Ergon Energy, Queensland University of Technology (QUT), University of Queensland (UQ)
Chief Investigators	Prof Tapan Saha (UQ) A/Prof. David Birtwhistle (QUT), Dr. J Lyall (QUT)
Research Fellow	Dr Bolarin Oyegoke
Postgraduate Students	Andrew Thomas (completed PhD), Frith Footit
Key Publications A.J. Thomas and T.K. Saha, “A theoretical investigation for the development of a water tree dielectric response model”, Proceedings of the 2006 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, October 15-18, 2006, Hyatt Regency Crown Center, Kansas City, Missouri, USA.  B. S. Oyegoke1 D. Birtwhistle1 J. Lyall1 T. K. Saha, “Water migration in degraded XLPE cables”, Proceedings of the 2006 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, October 15-18, 2006, Hyatt Regency Crown Center, Kansas City, Missouri, USA. Thomas, A., Saha, T. K., “The analysis of DC and AC conductivity in the detection of water tree degradation in XLPE cables Proceedings of the IEEE Power Engineering Society General Meeting, 12-16 June 2005 in San Francisco, California, USA         Ageing Experiments with Underground cables at Virginia Ergon laboratory

 

Investigation of key factors affecting the polarisation based diagnostics of power transformers

 

Electricity utilities are currently facing a major problem with an ageing population of power transformers. A number of recently developed polarisation based diagnostics produce sensitive indications of ageing and moisture in transformers. However, there is no suitable interpretation procedure available to separate the impacts of moisture and ageing by-products on these diagnostics. A number of innovative laboratory and field experiments will be performed to understand the mechanism of ageing and the end of life characteristics. The outcome will assist engineers and managers in making correct decisions on the maintenance and replacement strategies of aged transformers to avoid major power interruptions.

 

Funding	Australian Research Council Linkage Grant 07-09
Project Partners	University of Queensland (UQ), Powerlink, Connell Wagner Advance Technology Centre, Energy Australia
Chief Investigator	Prof Tapan Saha (UQ)
Research Fellow	Dr Chandima Ekanayake
Other Staff	Dr Andrew Thomas
Postgraduate Students	To be recruited

Investigation of Demand Diversity and New Generation Entry into Electricity Market Simulation Tools

The aim of this project is to investigate demand diversity and appropriate new generation entry into market simulation tools to ensure reliable and economic market operations. When assessing proposals for new generation investments in the National Electricity Market (NEM), prospective investors need to forecast future market outcomes by using appropriate simulation tools. Currently there is no literature addressing various aspects of market simulation techniques and models. It is important to understand whether the differences in modelling options and simulation techniques materially affect the simulation results. This proposal aims to provide unique tools for generation augmentation considering demand diversity in different NEM regions.

Funding	Australian Research Council Linkage Grant 2005 – 2007
Project Partners	Powerlink, TransGrid, NEMMCO, ESIPC, Transend, University of Queensland (UQ)
Chief Investigators	Prof Tapan Saha (UQ), Dr. Z Y Dong (UQ)
Research Fellow	Dr Jagath Fonseka (now moved to Powerlink Queensland)
Postgraduate Students	Carla Zieser (part-time) Kin Onn Wong (part-time)

 

Publications:

1. P.A.J. Fonseka, T.K. Saha, Z.Y. Dong, “A Probabilistic Simulation Model to Identify New Generation Investments,” Proceedings of the  IEEE – PES 2006 General Meeting, Tampa, Florida, USA.
2. KO Wong, TK Saha and ZY Dong, “A New Methodology for Generation Investment in the National Electricity Market of Australia”, Proceedings of IET Advances in Power System Control, Operation and Management (APSCOM), Hong Kong, 2006.
3. KO Wong, ZY Dong and TK Saha, “A Genetic Algorithm based Method for Deregulated Electricity Market Dispatch”, Proc IET APSCOM’06, Hong Kong
4. Carla Ziser, Z Y Dong, T K Saha, “Investigation of Weather Dependency and Load Diversity on Queensland Electricity Demand”, Proceedings of the 2005 Australasian Universities Power Engineering Conference, 26th September 2005, Hobart, Tasmania, Australia.
5. C. J. Ziser, Z. Y. Dong, and T. K. Saha, "Impact of Weather Dependency on Planning Decisions in the Australian National Electricity Market," proceedings of IET APSCOM, Hong Kong, 2006.
6. C. J. Ziser, Z. Y. Dong, and T. K. Saha, "Probabilistic Modelling of Demand Diversity and its Relationship with Electricity Market Outcomes," Proceedings of IEEE Power Engineering Society General Meeting, Tampa, Florida, 2007.

 

Advanced Planning Tools for the Prevention of System-wide Blackouts of Large Power Systems

Power systems are large, non-linear, interconnected and complex systems. World-wide deregulation of the power industry has only heightened their complexity. The recent drastic blackouts of North America, UK and Italy caused enormous financial losses within both the power utilities and the general community. Many factors can precipitate blackouts including equipment malfunction, insufficient transmission infrastructure, major system disturbances and/or voltage instability. This project will investigate advanced planning tools in assessing the conditions required for secure and stable operation of electricity system. Project outcome will lead to a comprehensive technical approach to prevent major blackouts in Australia.

 

We will investigate the mechanisms of system wide blackout of a large scale power system in a deregulated environment. This includes advanced techniques for the analysis of power system stability with the advantages of new technology - PowerformerTM - under a probabilistic framework for security assessment. The outcome will be a comprehensive technical approach to prevent major system wide blackouts. As a result of the project, we will be able to provide recommendations for the operation and management of independent power system operators and government authorities in the power industry to strategically prevent blackouts. The research particularly targets the National Electricity Market (NEM) of Australia, which supplies four eastern states and the national capital. Techniques developed in this project will be equally useful to other power systems as well.

 

Funding	Australian Research Council Discovery Grant 2006 – 2008
Chief Investigators	Prof Tapan Saha (UQ), Dr. Z Y Dong (UQ), Prof. G Ledwich (QUT)
Research Fellow	Dr Rui Yan
Postgraduate Students

Publications:

1. R. Yan, Z. Y. Dong, T. K. Saha and R. Majumder, “Power system   transient stability enhancement with an adaptive control design scheme using backstepping design”, Proceedings of the 2007 Power Engineering Society General Meeting to be held in June, in Tampa, Florida, USA.
2. Y. Mishra, Z. Y. Dong, T. K. Saha, and Y. S. Xue, “Power system stability enhancement in a deregulated environment using FACTS devices”, Paper accepted for the proceedings of the 8th International Power Engineering Conference (IPEC 2007) to be held from 3 - 6 Dec 2007 in Singapore.
3. Y. Mishra, T.K. Saha,  Z.Y. Dong, R. Majumder, “Investigation of Sensitivity based Load Ranking with Composite Load Model in Power System”, Paper accepted for the proceedings of the 8^th International Power Engineering Conference (IPEC 2007) to be held from 3 - 6 Dec 2007 in Singapore.

 

 

Emergency Control of Power Systems

 

Major power system blackouts are a low probability high impact event. The present responses from power system operators are able to avoid most predictable events. When more unexpected events occur the best response and the appropriate level need to be determined quickly. The integration of new tools for dynamic control and automated processes for emergency control offer a unique opportunity to reduce vulnerability and to limit the potential for one failure to trigger another. This project appraises the network points which are most stressed and determines the combination to relieve that stress without and excessive impact on customers.

 

A new emergency control method has been developed and published in a top conference. The student has been confirmed for his Mphil candidature. Major work is in progress.

 

Funding	Australian Research Council Discovery Grant 2005-07
Project Partners	University of Queensland, Queensland University of Technology
Chief Investigators	Prof. G Ledwich (QUT) Dr. Z Y Dong and Prof. Tapan Saha (UQ)
Postgraduate Students	Victer Ching (converted to part-time),
Research Fellow	Dr Jason Ford (took a lecturer position at QUT), two new staff appointments are in progress.

 

Publications

1. J. Ford, G. Ledwich and ZY Dong, “Nonlinear control of single-machine-infinite-bus transient stability”, Proceedings of the  IEEE  PES General Meeting 2006, Montreal, Quebec, Canada.

 

Investigations into the Impact of Electricity System Requirements on the Design of Powerformer^TM

In 1998, ASEA-Brown Bovery (ABB), unveiled a new type of generator capable of producing electricity directly at transmission voltages as high as 400 kV. ABB has named the new high voltage generator the PowerformerTM. The main aim of the project was to carry out technical studies of the interaction between the Powerformer and electricity systems, with particular reference to Queensland and national systems.  Three areas addressed including:

• To determine how the Powerformer’s parameters may be designed and chosen to assist system reliability and security, especially in the area of voltage stability.

• To investigate how the introduction of Powerformer affect the performance of the whole system under fault conditions with the ultimate goal being the selection of optimal design characteristics for application of Powerformer in the Queensland.

• To complete cost-benefits studies for Powerformer in the Queensland system, based on the outcomes of the preceding two areas of work.

 

Funding	Australian Research Council SPIRT Scheme 2000-2003
Project Partners	Powerlink, ABB Corporate Research, Alstom Power, Tarong Energy, Stanwell Corp. CS Energy , University of Queensland (UQ)
Chief Investigators	Prof Tapan Saha (UQ) Emeritus Professor Mat Darveniza (UQ)
Postgraduate Students	Craig Aumuller (PhD awarded May 2002) John McDonald (PhD awarded December 2004) Tika Limbu
Key Publications 1.        Aumuller, C., Saha, T.K., “Investigating the Impact of PowerformerTM on Voltage Stability by Dynamic Simulation”, IEEE Transactions on Power Systems, Volume: 18 Issue: 3 , Aug. 2003, Page(s): 1142 -1148 2.        Aumuller, C., Saha, T.K., “Determination of Power System Coherent Bus Groups by Novel Sensitivity Based Method for Voltage Stability Assessment”, IEEE Transactions on Power Systems, Volume: 18, Issue: 3, Aug. 2003, Page(s): 1157 -1164 3.         McDonald, J.D. F., and Saha, T. K., "Analytical representation of the relationship between generator design and system fault behaviour,"  IEEE Transactions on Power Systems, Vol. 20, pp. 1215 - 1223 4.         McDonald, J. D. F., Saha, T.K., “Selection of Generator Fault Impedances for Enhancement of Network-Wide Fault Behaviour”, Journal of Electrical and Electronics Engineering Australia, Vol.22, No. 3, pp. 235-242, Published by Engineers Australia College of Electrical Engineers, 2003.

 

Electricity Market Security Assessment and Management

The electric power industry restructuring and deregulation resulted in vertically integrated power companies being separated into smaller, competing and functionally separate entities, and introduced the competitive markets for electricity. Like other markets, attention shall be paid to such as market structure and rules; however, security of the electricity market shall also be considered based on its special feature defined by the characteristics of electricity. Regardless of the market model chosen, it is still essential to carefully balance the power requirements of the supply side and demand side in the presence of disturbances. It is well known that this balance is required to maintain system voltage, frequency and angle stability of the network. This project investigates methods to achieve system security via planning and management. Optimization techniques from both traditional and artificial intelligence based ones are employed for security assessment. The objective of the project to establish a security assessment and management framework, which can assist the electricity market managers in decision making aimed at maximizing their profits as well as maintaining the system security.

Funding	UQ ECR Award and other resources
Project Partners	University of Queensland
Chief Investigators	Dr. Z Y Dong (UQ) Prof Tapan Saha (UQ)
Postgraduate Students	Zhao Xu, Sheng How Goh
Key Publications 1.  Goh, S. H., Xu, Z., Dong, Z. Y., Saha, T.K.,  “Economic Constrained Transfer Capability Assessment”, Proceedings of the  IEEE  Power Engineering Society General Meeting, 6-10 June, 2005, San Francisco, USA 2.   Z. Xu, ZY Dong and KP Wong, "Genetic algorithm-based spinning reserve dispatching in a competitive electricity environment", International Journal of Systems Science, Vol. 35, pp. 847 - 853 3.   Z. Xu and Z.Y. Dong, "Market Based Planning of Transmission Network using Genetic Algorithm", Proceedings of the  IEEE 8th International Conference on Probability Methods Applied to Power Systems, September 13-16, 2004, Iowa State University, Ames, Iowa, USA. 4.   Z. Y. Dong and D. J. Hill, “Power System Reactive Planning under Deregulated Electricity”, Proc. IEE APSCOM'2000, Hong Kong, 2000, pp. 70-75.Market”, Proc. IEE APSCOM'2000, Hong Kong, 2000, pp. 70-75.

 

Probabilistic Power System Small Signal Stability Assessment

Power systems are experiencing more and more uncertainties especially under a deregulated environment. The system uncertainty may come from various sources but the main contribution is from uncertainties in system parameters and forecasted loads. This has resulted in challenges for system planners in an open assess electricity market. In order to have a comprehensive picture of the system stability in planning, probabilistic stability assessment is attracting more and more attention over the traditional deterministic approach. Small signal stability is the ability of power system to maintain synchronism under small disturbances. The small signal stability problem is usually due to insufficient damping of system oscillations. The objective of this project is to perform theoretical study on probabilistic small signal stability so that the study results can be used to help Regional Transmission Organizations (RTOs) and Independent System Operators (ISOs) perform planning studies under the open access environment.

Funding	Electric Power Research Institute (EPRI), USA
Project Partners	EPRI (USA), University of Queensland
Chief Investigators	Dr. Z Y Dong (UQ)
Postgraduate Students	Zhao Xu
Key Publications 1. ZY Dong, C.K. Pang and P. Zhang, "Power System Sensitivity Analysis for Probabilistic Small Signal Stability Assessment in a Deregulated Environment" International Journal of Control, Automation and Systems, Vol. 3, pp. 355 - 362, The Institute of Control, Automation and Systems Engineering. 2. Z. Xu, ZY Dong and P Zhang, “Probabilistic Small Signal Analysis using Monte Carlo Simulation”, #635, Proceedings of the  IEEE PES General Meeting 2005, June 2005, San Francisco, USA 3. C.K. Pang, ZY Dong, P Zhang and Y Xia, “Probabilistic Analysis of Power System Small Signal Stability Region”, invited paper, Proc. 5th International Conference on Control and Automation (ICCA05), Budapest, Hungary, 26-29 June 2005.

 

Stability Analysis and Control for Large Scale Power Systems Incorporating FACTS Devices

Power system stability analysis and control is one of the most important issues in power systems. The problem becomes more serious in power systems with long transmission lines, such as the transmission systems in Australia. The ability of a power system to maintain stability depends to a large extent on the controls available on the system. Consequently, the study and design of power system controls are very important for expanding systems. This project aims at investigating into stability assessment and control of large scale interconnected power systems incorporating FACTS (Flexible AC Transmission System) devices in a deregulated electricity market.

Funding	ARC Linkage with EPRI, USA; MAPI, Australia and Nanyang Technological University, Singapore
Project Partners	EPRI (USA), MAPI, Nanyang Technological University, University of Queensland
Chief Investigators	Dr Z Y Dong (UQ) A/Prof Y Wang (Nanyang Technological University)
Postgraduate Students	Mr. Guang Ya Yang