Science and Technology Studies Commons^™

Over-Voltage Mitigation Within Distribution Networks With A High Renewable Distributed Generation Penetration, Joel Kennedy, Philip Ciufo, Ashish Agalgaonkar

Dr Philip Ciufo

The rapid growth of grid-connected distributed generation has increased the likelihood of over-voltage occurrences in distribution networks. In recent times, much research has taken place in order to develop a control strategy to mitigate the voltage rise problem. However, most of the published strategies require re-tuning when additional resources are connected, or have a strong dependence on network parameters, such as fault level. This paper proposes a novel over-voltage mitigation scheme that has many advantages not observed in literature. Firstly, the control scheme can integrate with an existing feeder in a plug-and-play fashion. No prior analysis is necessary to configure …

A Secure And Effective Anonymous User Authentication Scheme For Roaming Service In Global Mobility Networks, Fentong Wen, Willy Susilo, Guomin Yang

Professor Willy Susilo

In global mobility networks, anonymous user authentication is an essential task for enabling roaming service. In a recent paper, Jiang et al. proposed a smart card based anonymous user authentication scheme for roaming service in global mobility networks. This scheme can protect user privacy and is believed to have many abilities to resist a range of network attacks, even if the secret information stored in the smart card is compromised. In this paper, we analyze the security of Jiang et al.'s scheme, and show that the scheme is in fact insecure against the stolen-verifier attack and replay attack. Then, we …

Improvements On An Authentication Scheme For Vehicular Sensor Networks, Joseph K. Liu, Tsz Hon Yuen, Man Ho Au, Willy Susilo

Professor Willy Susilo

In a recent paper, Shim (2012) presented a very interesting authentication scheme for vehicular sensor networks. Shim claimed that the scheme is secure against the highest adopted level of attack, namely the chosen-message attack (CID-CMA). Nevertheless, we find that the proof in Shim's paper does not actually prove that the scheme is secure in this level. Instead, it can only ensure that the scheme is secure in a strictly weaker level of attack, the adaptive chosen-identity and no-message attack (CID-NMA). In this paper, first we show that there exist some security risks in vehicular networks if a scheme, which is …

Large Networks Of Vertical Multi-Layer Graphenes With Morphology-Tunable Magnetoresistance, Zengji Yue, Igor Levchenko, Shailesh Kumar, Donghan Seo, Xiaolin Wang, S X. Dou, Kostya Ken Ostrikov

Shi Xue Dou

We report on the comparative study of magnetotransport properties of large-area vertical few-layer graphene networks with different morphologies, measured in a strong (up to 10 T) magnetic field over a wide temperature range. The petal-like and tree-like graphene networks grown by a plasma enhanced CVD process on a thin (500 nm) silicon oxide layer supported by a silicon wafer demonstrate a significant difference in the resistance-magnetic field dependencies at temperatures ranging from 2 to 200 K. This behaviour is explained in terms of the effect of electron scattering at ultra-long reactive edges and ultra-dense boundaries of the graphene nanowalls. Our …

Impact Of Wind Generator Control Strategies On Flicker Emission In Distribution Networks, Lasantha Meegahapola, Sarath Perera

Dr Lasantha G Meegahapola

Renewable power generators are increasingly being integrated to electricity networks to achieve future renewable energy targets in power generation. In particular, wind power generation has already reported substantial penetration levels in electricity networks. Traditionally, flicker phenomenon is considered to be one of the power quality issues in power distribution networks due to fluctuating consumer loads connected to the network. Large-scale integration of wind power generators may create significant voltage fluctuations in distribution feeders due to stochastic and intermittent nature of the wind resources. This study aims to investigate and characterize the flicker emission under different control strategies for DFIG based …

Characterisation Of Flicker Emission And Propagation In Distribution Networks With Bi-Directional Power Flows, D Perera, L Meegahapola, S Perera, P Ciufo

Dr Lasantha G Meegahapola

With the increasing penetration levels of intermittent and fluctuating energy sources such as wind generating systems in the electricity grid, resulting voltage fluctuations and flicker can be expected to become an important power quality considerations. Due to significant bidirectional power flows resulting from large renewable power generation systems connected to downstream, voltage fluctuations may propagate from downstream to upstream. The work presented in this paper investigates and characterises flicker emission and propagation resulting from fluctuating generating sources connected to a distribution network. Mathematical models are developed for flicker emission under different generator control strategies and flicker propagation to upstream network. …

Comparative Analysis Of Dynamic Line Rating Models And Feasibility To Minimise Energy Losses In Wind Rich Power Networks, Mathew Simms, Lasantha Meegahapola

Dr Lasantha G Meegahapola

Wind power generation has indicated an exponential increase during last two decades and existing transmission network infrastructure is increasingly becoming inadequate to transmit remotely generated wind power to load centres in the network. The dynamic line rating (DLR) is one of the viable solutions to improve the transmission line ampacity during high wind penetration without investing on an additional transmission network. The main objective of this study is to identify the basic differences between two main line rating standards, since transmission network service providers (TNSPs) heavily depend on these two standards when developing their line rating models. Therefore, a parameter …

Flicker Propagation Analysis In Distribution Networks With Embedded Generation, D Perera, L Meegahapola, S Perera, P Ciufo

Dr Lasantha G Meegahapola

Embedded generators such as wind generators can produce observable voltage fluctuations during variable wind conditions hence flicker. The flicker produced by such intermittent and fluctuating generating sources can propagate to other parts of the distribution network while creating power quality issues in distribution feeders. This study presents a flicker emission analysis for a doubly-fed induction generator (DFIG) based wind farm and investigate the pertinent factors which influence flicker propagation and attenuation in distribution feeders. Study has shown that voltage fluctuations are significantly influenced by the attenuation characteristics of various load types (i.e. constant power, impedance and current loads) connected to …

Large Networks Of Vertical Multi-Layer Graphenes With Morphology-Tunable Magnetoresistance, Zengji Yue, Igor Levchenko, Shailesh Kumar, Donghan Seo, Xiaolin Wang, S X. Dou, Kostya Ken Ostrikov

Zengji Yue

We report on the comparative study of magnetotransport properties of large-area vertical few-layer graphene networks with different morphologies, measured in a strong (up to 10 T) magnetic field over a wide temperature range. The petal-like and tree-like graphene networks grown by a plasma enhanced CVD process on a thin (500 nm) silicon oxide layer supported by a silicon wafer demonstrate a significant difference in the resistance-magnetic field dependencies at temperatures ranging from 2 to 200 K. This behaviour is explained in terms of the effect of electron scattering at ultra-long reactive edges and ultra-dense boundaries of the graphene nanowalls. Our …

A Multiagent Approach For Decentralized Voltage Regulation In Power Distribution Networks Within Dgs, Fenghui Ren, Minjie Zhang, Danny Sutanto

Dr Fenghui Ren

Voltage regulation (VR) is a procedure to keep voltages in a distribution network (DN) within normal limits. Conven- tionally, a voltage regulator can read voltage levels from pre- dened measures, and regulate the voltages. However, due to lacking of a distributed generator's (DG) information, the unexpected electricity from a DG will mislead readings on voltages levels, so as to disturb the VR in a DN. Adjust- ing a DG's reactive power output is an alternative way for VR. However, because of limited penetration levels, DGs need to collaborate with other devices in order to provide an eective voltage regulation. Therefore, …

Securing Dsr Against Wormhole Attacks In Multirate Ad Hoc Networks, Shams Qazi, Raad Raad, Yi Mu, Willy Susilo

Dr Raad Raad

A wormhole attack is one of the hardest problems to detect whereas it can be easily implanted in any type of wireless ad hoc network. A wormhole attack can easily be launched by the attacker without having knowledge of the network or compromising any legitimate nodes. Most existing solutions either require special hardware devices or make strong assumptions in order to detect wormhole attacks which limit the usability of these solutions. In this paper, we present a security enhancement to dynamic source routing (DSR) protocol against wormhole attacks for ad hoc networks which relies on calculation of round trip time …

Comparison Of Methodologies For Assessment Of Harmonic Current Emission Limits For Large Installations Connected To Lv Networks, Biyanvilage Perera, Sarath Perera, Philip Ciufo, Victor J. Gosbell

Dr Philip Ciufo

With the proliferation of large, disturbing installations (loads and distribution generators) connected to public low voltage networks, managing the harmonic voltage levels in the network has become a key concern to distribution network service providers (DNSPs). Therefore, it is important that DNSPs limit the harmonic current emission by individual installations. This paper reviews a number of methodologies that exist in the current technical literature in relation to the assessment of harmonic current emission limits for disturbing installations connected to the public LV network. Application of these methodologies is demonstrated through a case study on a test network. The study shows …

Flicker Propagation Analysis In Distribution Networks With Embedded Generation, D Perera, L Meegahapola, S Perera, P Ciufo

Dr Philip Ciufo

Embedded generators such as wind generators can produce observable voltage fluctuations during variable wind conditions hence flicker. The flicker produced by such intermittent and fluctuating generating sources can propagate to other parts of the distribution network while creating power quality issues in distribution feeders. This study presents a flicker emission analysis for a doubly-fed induction generator (DFIG) based wind farm and investigate the pertinent factors which influence flicker propagation and attenuation in distribution feeders. Study has shown that voltage fluctuations are significantly influenced by the attenuation characteristics of various load types (i.e. constant power, impedance and current loads) connected to …

Converging And Coexisting Systems Towards Smart Surveillance, Katina Michael, Mg Michael

Professor Katina Michael

Tracking and monitoring people as they operate within their personal networks benefits service providers and their constituents but involves hidden risks and costs.

Automatic identification technologies, CCTV cameras, pervasive and mobile networks, wearable computing, location-based services and social networks have traditionally served distinct purposes. However, we have observed patterns of integration, convergence and coexistence among all these innovations within the information and communication technology industry.1For example, ‘location-based social networking’ can draw on a smart phone's capacity to identify a user uniquely, locate him within 1–2m and share this information across his social network in real time. The resulting ability to …

The Limits And Opportunities Of Networks: Municipalities And Canadian Climate Change Policy, Christopher D. Gore

Christopher D Gore

Research on climate change policy and politics has become increasingly focused on the actions and influence of subnational governments. In North America, this attention has been particularly focused on why subnational governments have taken action in the absence of national leadership, what effect action might have on future national climate policy, and whether the collective action of networks of municipal governments are reshaping and challenging the character of national and global climate governance. This paper examines Canadian municipal climate in light of the absence of a comprehensive and effective climate national strategy. The paper considers various reasons why local governments …