Toan Phung

• PhD in Electrical Engineering
• Professor (Associate) at UNSW Sydney

Alumina-tri-hydrate (ATH) and Silica (SiO2) microfillers are widely used to enhance the pollution performance of room temperature vulcanized (RTV) silicone rubber (SR) coatings which are now increasingly being used in porcelain-based bushings of oil-immersed transformers to enhance their operational safety. However, exposure of SR to transformer oi...

Overhead transmission line insulators are non-conductive materials that separate conductors from grounded transmission towers. Once in operation, they frequently experience environmental pollution and electrical or mechanical stress. Since adverse operational conditions can lead to insulation failure, regular inspections are essential to prevent po...

Silicone rubber (SR) is a leading polymer used in electrical outdoor insulation applications due to its superior hydrophobic characteristics. However, the low flame and electrical surface discharge resistance of SR limit its broad viability and challenge its integrity in severe outdoor working conditions. This work attempts to explore the flame ret...

Variable speed drives (VSDs) are widely utilized to control motors such as pumps, compressors, fans, etc. However, the endurance of motor winding insulation under repetitive voltage pulse excitation is weakened, resulting in premature failure and shortening the expected operating life. This article reviews the literature of investigations spanning...

When using an antenna near a high voltage conductor for the Partial Discharge (PD) detection application, curiosity for understanding any share of capacitive coupling in this process will arise. In usual applications of the Ultra-High Frequency (UHF) sensors, the antenna’s plates are not near a high voltage conductor so it is inferred undoubtedly t...

In the evolving landscape of critical infrastructure security, the increasing sophistication of cyber threats poses challenges, particularly to the power grid’s new technology infrastructure. Despite traditionally being considered passive elements, power transformers, as critical components of the grid, are now equipped with smart technologies and...

Ensuring the fire safety of high voltage (HV) outdoor insulators is key to maintain the reliable operation of the electrical grid. This requires the careful selection of suitable polymeric composite materials with excellent electrical tracking, erosion, and fire resistance characteristics. To improve their performance against electrical tracking an...

Silicone rubber composite is a priority electrical insulating material to be used in high-voltage outdoor insulation applications. The low electrical tracking/erosion and poor flame resistance performance of silicone rubber once ignited substantially reduce its working life. This paper attempts to investigate the tracking/erosion performance of roo...

The rise of cyber threats on critical infrastructure and its potential for devastating consequences, has significantly increased. The dependency of new power grid technology on information, data analytic and communication systems make the entire electricity network vulnerable to cyber threats. Power transformers play a critical role within the powe...

Room temperature vulcanized (RTV) silicone rubber is widely used as a protective coating for power transformer bushings due to its exceptional hydrophobicity, hydrophobicity recovery and superior anti-pollution flashover properties. However, the performance of silicone rubber may experience significant deterioration when exposed to transformer mine...

Experimental results suggested that the introduction of montmorillonite (MMT) nanoclay powder and chopped glass fibre (CGF) substantially enhanced the flame retardancy and thermal stability of silicone/ aluminium hydroxide (ATH) powder-based coatings. It was evidenced by the fire growth index (FGI) reduced to 0.401 in SE from 1.243 kW.m⁻².s⁻¹ in SB...

The integrity of polydimethylsiloxane (PDMS) based silicone rubber (SR) is highly critical in the electrical insulation industry during a wildfire event. In this work, SR composites are prepared with milled glass fires (MGFs) and graphene nanoplatelets (GNPs) to study the limiting oxygen index (LOI), cone calorimeter parameters, electrical breakdow...

In this work, the thermal stability, thermal conductivity, dielectric frequency response, smoke factor (SF), fire performance index (FPI), and fire growth index (FGI) of silicone elastomer composites were studied and compared. TGA/DTG results indicated that the addition of graphene nanoplatelets (GNP)/milled E-glass fibres (MGF) improved the therma...

This paper reports the fire and smoke behaviour along with the DC electrical volume resistivity of silicone rubber filled with alumina trihydrate (ATH), milled glass fibre rods (GFRs) and graphene nanosheets (GNs). Results show that there is a significant de-escalation in the fire and smoke parameters of filled composites. As seen in SRE, adding a...

Outdoor insulators in high voltage power lines serve as electrical insulation barriers and mechanical supports for live conductors. They are exposed to environmental contaminants and physical deterioration or damage. Hence, polluted insulator analysis is a fundamental concern for proper power system operation. This study harvests a comprehensive in...

We propose herein a novel optical sensing technology using liquid crystal based transducers to measure simultaneously voltage and current from overhead power lines in real time. Doing so, we implemented a proof-of-principle system based on this approach and we demonstrated not only good accuracy, but also small phase shift and adequate bandwidth fo...

Frequency Response Analysis (FRA) is almost certainly the most efficient and well-established method for evaluating the mechanical integrity of transformer active part. FRA has a solid background in both industrial practice and academic research. Besides conventional visual analysis, a statistical analysis has been applied to the FRA data interpret...

Room temperature vulcanized (RTV) silicone rubber filled with aluminum trihydrate (ATH) is substantially engaged in electrical outdoor insulation applications. The pristine silicone rubber is highly combustible. ATH filled silicone rubber offers excellent electrical insulation but lacks in providing adequate flame retardancy. This short communicati...

DC microgrids have advantages over AC microgrids in terms of system efficiency, cost, and system size. However, a well-designed overcurrent protection approach for DC microgrids remains a challenge. Recognizing this, this paper presents a novel differential evolution (DE) based protection framework for DC microgrids. First, a simplified DC microgri...

Incidents of DC series arc faults in Photovoltaic (PV) systems are becoming more common, posing significant threat to properties and human safety. Machine Learning (ML) based methods, developed recently, have demonstrated better performance in many fault diagnosis tasks. However, an unresolved challenge affecting their performance is the problem ca...

Room temperature vulcanized (RTV) silicone rubber is significantly engaged for high voltage outdoor insulation for its superb hydrophobic and pollution flashover performance. However, it tends to degrade in form of carbon tracking and erosion due to severe ohmic heating and dry band arcing activities on its surface. This work reports the physical c...

DC arc faults, especially series arc faults, are becoming more common in photovoltaic (PV) systems. Without timely detection and interruption, such dangerous events can cause catastrophic fires, posing severe threat to human safety and properties. This paper presents a review on DC series arc fault detection using machine learning (ML) in PV system...

This paper presents a state-of-the-art review on machine learning (ML) based intelligent diagnostics that have been applied for partial discharge (PD) detection, localization, and pattern recognition. ML techniques, particularly those developed in the last five years, are examined and classified as conventional ML or deep learning (DL). Important f...

Polymeric-insulated cables, especially cross-linked polyethylene (XLPE) cables, are widely used in power system transmission and distribution networks. A cable failure can result in lengthy outages and substantial economic loss to the electrical utilities. One of the primary reasons for cable fault is insulation degradation over the service time. V...

Silicone rubber filled with micron-alumina trihydrate (ATH) is a substantially used composite material for high voltage outdoor insulators. This article investigates the effect of nano-boron nitride (BN) addition on the dielectric, thermal stability and thermal conductivity of solely micron-ATH-filled silicone rubber by fabricating coalesced networ...

In this paper, a comparative study including measurement and modeling of partial discharge for various void geometries (cylinder, block, and prisms) at very low frequency (VLF) and power frequency (PF) voltage is presented. Results from experiments and simulations are presented with phase-resolved discharge patterns and integrated parameters (maxim...

Silicone rubber (SiR) composite material is a modern-day insulator for high voltage outdoor applications. The imperfection attributed to SiR is its weak resistance to tracking and erosion when exposed to outdoor polluted environment which reduces its operational lifetime. This work investigates the performance of SiR with the addition of 0, 1, 2.5,...

Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge‐induced thermal depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared thermal distribution, and leakage current de...

Dielectric response measurement based on the polarisation and depolarisation current (PDC) method is a diagnostic tool commonly employed to the insulation condition assessment of power apparatus. In this paper, experimental studies are carried out on short sections of service-aged XLPE cable. Daniel's normalisation is applied to estimate the differ...

Cross-linked polyethylene (XLPE) insulated power cables are widely used in transmission and distribution networks. The enhanced localised electrical field/stress can result in surface discharges (SD), i.e. partial discharges on the surface of the dielectric. To measure discharges, very low frequency (VLF-0.1 Hz or lower) excitation has emerged as a...

Recovery voltage measurement (RVM) is one of the common diagnostic techniques for the condition assessment of electrical insulation. The method has been used to examine the dielectric response, especially deterioration or depolymerisation of the polymeric insulation under ageing condition. In this study, a mathematical model of the RVM measurement...

In this paper, surface trap distribution and the affected surface charge transport properties in epoxy/Al2O3 nanocomposites were studied to provide theoretical and experimental basis for improving surface flashover performance in vacuum. Four different contents of nano-Al2O3 particles were doped into epoxy and different trap distribution of samples...

In any sustainable electrical systems, various high‐voltage (HV) power apparatuses such as electrical cable, transformer etc. play a pivotal role to transfer electrical energy from the generation end to the consumer end. The degradation due to electrical stress is very unlikely to avoid in operation. Prominently, the insulation system is mostly exp...

Ethylene propylene diene monomer (EPDM) is a polymer widely used for insulation in high voltage outdoor insulators and cables. It is well accepted that appropriate addition of micron particles to form a composite can enhance its insulation performance. This work reports improvement on the dielectric breakdown strength, tracking failure time, mechan...

Digital signal processing (DSP) methods have been used by many researchers for detection and classification of transient disturbances because of their fast and powerful abilities to recognise waveform distortions. However, some DSP methods such as the wavelet transformation (WT) show less accuracy when applied to noisy real data. In this study, dis...

For outdoor electrical insulation applications, ethylene propylene diene monomer (EPDM) is among the most prominent materials by virtue of its better contamination performance in the field. However, EPDM is prone to thermally depolymerize due to temperature build-up on the surface during dry band arcing which initiates carbonized tracking. This pap...

Partial discharge (PD) monitoring is essential for insulation diagnostic of high voltage power transformers. PD activities can generate electromagnetic waves in the ultra-high frequency (UHF) range. The signals captured from several antennas installed inside the transformer can be analyzed to determine their time of arrival (TOA) and time differenc...

Dielectric response analysis is one approach for the condition assessment of high voltage insulation systems, and measurement of the dissipation factor or tan δ is widely used in practice. This article presents an experimental study of DF measurement over the frequency range from 1 mHz to 50 Hz. Three different short sections of service-aged 11-kV...

Dielectric response analysis is one approach for the condition assessment of high voltage insulation systems, and measurement of the dissipation factor or tan δ is widely used in practice. This article presents an experimental study of DF measurement over the frequency range from 1 mHz to 50 Hz. Three different short sections of service-aged 11-kV...

The enhancement of DC breakdown strength in polypropylene/alumina nanocomposites (NCs) with low filler content (1 wt%) while the obviously increased partial discharge (PD) resistance at higher filler content (15 and 20 wt%), are observed. Possible mechanisms underlying such contrastive performance are proposed based on considering a combination of...

DC arc faults present a challenging protection problem in DC systems, such as photovoltaic and electric vehicle supply systems. Incidents of DC arc faults in DC systems are becoming more common especially for series arc faults, and if undetected, would finally cause severe damage to the systems. This paper studies DC series arc fault characteristic...

The general method for identifying the partial discharge type in a power transformer is based on their fingerprints in the form of phase-resolved discharge patterns. In the case of multiple defects, traditional clustering methods can be applied for separation of active sources. However, such an approach is impractical for online real-time monitorin...

With the penetration of renewable energy, the electrical grid tends to be more flexible and distributed. Microgrid is a promising solution to deal with the rising challenges in distributed generation. Droop control is often adopted to handle power sharing for distributed generation control in microgrids, however it cannot guarantee required sharing...

DC arc faults, especially series arcing, can occur in photovoltaic (PV) systems and pose a challenging detection and protection problem. Machine learning based methods are increasingly being used for fault diagnosis applications. However, the performance of such detection algorithms will degrade because of variations between the source domain data...

Partial discharge (PD) measurement and identification have great importance to condition monitoring of power transformers. In this paper, a new method for recognition of single and multi-source of PD based on extraction of high level image features has been introduced. A database, involving 365 samples of phase-resolved PD (PRPD) data, is developed...

As one of the most classical digital signal processing (DSP) techniques, the wavelet transformation (WT) has been applied to detect and classify power system disturbances for many years. However, its performance is easily affected by harmonics. This makes it difficult to detect and classify disturbances occurring in an islanded micro‐grid, especial...

Condition monitoring of an operating apparatus is essential for lifespan assessment and maintenance planning in a power system. Electrical insulation is a critical aspect to be monitored, since it is susceptible to failure under high electrical stress. To avoid unexpected breakdowns, the level of partial discharge (PD) activity should be continuous...

Surface discharge often occurs between a solid dielectric and high voltage conductor which is one of the major insulation failure modes. In this paper, surface discharge characteristics (phase resolved patterns, magnitude and repetition rate) of EPDM/BN nanocomposites are studied. Also investigated are the dielectric response, volume resistivity an...

Transformers are the key component in power system transmission and distribution networks. Condition based maintenance will increase their expected life and online monitoring is essential to ensure operation reliability. In this paper, a new approach to transformer online monitoring is provided based on partial discharge (PD) measurement. Simultane...

Ethylene propylene diene monomer (EPDM) is a polymeric material widely used for high-voltage insulation. This Letter reports the dielectric and thermal properties of EPDM co-filled with micro- and nano-BN particles. EPDM composite samples with different micro and micro/nano co-filled contents are prepared by melt-blending and followed by hot press...

Power transformer partial discharge signal measurement using Radio Frequency method has advantages over IEC 60270 ‘apparent charge’ measurement method for online monitoring due to greater immunity against external interference. However, the lack of a well-defined calibration relationship between the two methods is main disadvantage of RF method. Si...

High impedance faults (HIFs) on overhead power lines are known to cause fires. They are difficult to detect using conventional protection relays because the fault current is insufficient to cause tripping. The delay in detecting HIFs can result in severe bushfires and energy losses; hence a high throughput, low latency detection scheme needs to be...

DC microgrid which has more natural interface with renewable energy such solar energy harnessing, and is relatively easier to operate compared with AC microgrid is gaining more and more interest. In this paper, the control methods for PV dominated DC microgrid has been reviewed and testified. In addition, among all the faults, DC arc fault can caus...

This study attempts to elucidate whether the addition of micro and/or nano silica (SiO2) particles can enhance the resistance of pure polydimethylsiloxane (PDMS) against synergistic effects of UV, temperature and high voltage stress. Four types of composites (U-SR, M-SR, MN-SR and N-SR) are fabricated by adding micro and/or nano silica particles an...

Feasibility study on implementing wind energy harvesting system on moving train is discussed in this study. Wind turbines installation over the train roof is suggested and analyzed from different aspects. Practical aspects of wind energy utilization are discussed, and challenges are highlighted. Calculations of wind power generation for wagon roof...

Smart monitoring applications in all aspects of power systems are becoming increasingly popular because of the indirect effect on energy management and the smart grid. In this regard, high voltage equipment monitoring and real-time assessment are critical. Among these evaluations, transformer life and condition assessment has been considered for ma...

High impedance faults (HIFs) on overhead power lines are known to cause fires. They are difficult to be detected by conventional protection relays because the fault current is insufficient to cause tripping. The delay in detecting and isolating this kind of faults can result in severe bushfires due to arcing at the contact surface. Because of that,...

Thermal depolymerisation induced tracking and erosion of polymeric insulators is one of the key insulation failure modes and this process adversely affects the reliability of power delivery networks. This study reports the tracking, erosion and thermal distribution of micron-AlN and micron-AlN + nano-SiO(2) co-filled silicone rubber composites. A t...

Surface flashover properties should meet stringent requirements for the use in electrical equipment under high voltage DC environments. With the aim of enhancing surface flashover properties and understanding the mechanisms involved at ambient conditions, epoxy nanocomposites with different weight proportions of nano-TiO2 were prepared. A silane co...

Integration of renewable energy including solar energy is growing faster than ever before. Solar energy supplies more than 1.3% of global power, and it is predicted to become the largest electricity source by 2050 with about 11% of global power consumption. However, the improper installation, non-frequently scheduled maintenance, and aging effect c...

Carbonized tracking due to thermal depolymerization on weather-shed materials of polymeric insulators is one of the key insulation failure modes, adversely affecting the reliability of power delivery networks. This paper investigates the tracking process and thermal distribution of micron-AlN and hybrid micron-AlN + nano-silica filled silicone rubb...

An important application in the growing field of Unmanned Aerial Vehicles (UAVs) is in monitoring and inspection of high voltage power lines and electrical networks. The UAV based monitoring method will save energy, simplify access to impassable or remote areas, reduce inspection cost, and automate the inspection process. However, the battery capac...