Rough Fuzzy Control of SVC for Power System Stability Enhancement

Modern power systems have become more complex due to the growth in load demand, the installation of Flexible AC Transmission Systems (FACTS) devices and the integration of new HVDC links into existing AC grids. On the other hand, the introduction of the deregulated and unbundled power market operational mechanism, together with present changes in generation sources including connections of large renewable energy generation with intermittent feature in nature, have further increased the complexity and uncertainty for power system operation and control. System operators and engineers have to confront a series of technical challenges from the operation of currently interconnected power systems. Among the many challenges, how to evaluate the steady state and dynamic behaviors of existing interconnected power systems effectively and accurately using more powerful computational analysis models and approaches becomes one of the key issues in power engineering. The traditional computing techniques have been widely used in various fields for power system analysis with varying degrees of success. The rapid development of computational intelligence, such as neural networks, fuzzy systems and evolutionary computation, provides tools and opportunities to solve the complex technical problems in power system planning, operation and control.

Multi-rotor with suspended load: System dynamics and control toolbox

There is an increasing demand for Unmanned Aerial Systems (UAS) to carry suspended loads as this can provide significant benefits to several applications in agriculture, law enforcement and construction. The load impact on the underlying system dynamics should not be neglected as significant feedback forces may be induced on the vehicle during certain flight manoeuvres. The constant variation in operating point induced by the slung load also causes conventional controllers to demand increased control effort. Much research has focused on standard multi-rotor position and attitude control with and without a slung load. However, predictive control schemes, such as Nonlinear Model Predictive Control (NMPC), have not yet been fully explored. To this end, we present a novel controller for safe and precise operation of multi-rotors with heavy slung load in three dimensions. The paper describes a System Dynamics and Control Simulation Toolbox for use with MATLAB/SIMULINK which includes a detailed simulation of the multi-rotor and slung load as well as a predictive controller to manage the nonlinear dynamics whilst accounting for system constraints. It is demonstrated that the controller simultaneously tracks specified waypoints and actively damps large slung load oscillations. A linear-quadratic regulator (LQR) is derived and control performance is compared. Results show the improved performance of the predictive controller for a larger flight envelope, including aggressive manoeuvres and large slung load displacements. The computational cost remains relatively small, amenable to practical implementations.

An automated emergency landing system for fixed-wing aircraft: Planning and control

A number of hurdles must be overcome in order to integrate unmanned aircraft into civilian airspace for routine operations. The ability of the aircraft to land safely in an emergency is essential to reduce the risk to people, infrastructure and aircraft. To date, few field-demonstrated systems have been presented that show online re-planning and repeatability from failure to touchdown. This paper presents the development of the Guidance, Navigation and Control (GNC) component of an Automated Emergency Landing System (AELS) intended to address this gap, suited to a variety of fixed-wing aircraft. Field-tested on both a fixed-wing UAV and Cessna 172R during repeated emergency landing experiments, a trochoid-based path planner computes feasible trajectories and a simplified control system executes the required manoeuvres to guide the aircraft towards touchdown on a predefined landing site. This is achieved in zero-thrust conditions with engine forced to idle to simulate failure. During an autonomous landing, the controller uses airspeed, inertial and GPS data to track motion and maintains essential flight parameters to guarantee flyability, while the planner monitors glide ratio and re-plans to ensure approach at correct altitude. Simulations show reliability of the system in a variety of wind conditions and its repeated ability to land within the boundary of a predefined landing site. Results from field-tests for the two aircraft demonstrate the effectiveness of the proposed GNC system in live operation. Results show that the system is capable of guiding the aircraft to close proximity of a predefined keyhole in nearly 100% of cases.

Active Adaptive Gyrostabiliser Control System

A gyrostabiliser control system and method for stabilising marine vessel motion based on precession information only. The control system employs an Automatic Gain Control (AGC) precession controller (60). This system operates with a gain factor that is always being gradually minimized so as to let the gyro flywheel (12) develop as much precession as possible - the higher the precession, the higher the roll stabilising moment. This continuous gain change provides adaptation to changes in sea state and sailing conditions. The system effectively predicts the likelihood of maximum precession being reached. Should this event be detected, then the gain is rapidly increased so as to provide a breaking precession torque. Once the event has passed, the system again attempts to gradually decrease the gain.

Fault tolerant vessel stabiliser control system

A vessel stabilizer control system includes a sensor fault detection means which senses the availability of sensing signals from a gyrostabilizer precession motion sensor and a vessel roll motion sensor. The control system controls the action of a gyro-actuator which is mechanically coupled to a gyrostabilizer. The benefit of employing fault sensing of the sensors providing the process control variables is that the sensed number of available process control variables (or sensors) can be used to activate a tiered system of control modes. Each tiered control mode is designed to utilize the available process control variables to ensure safe and effective operation of the gyrostabilizer that is tolerant of sensor faults and loss of power supply. A control mode selector is provided for selecting the appropriate control mode based on the number of available process control variables.

Boarding Control System - for Improved Accessibility to Offshore Wind Turbines

This paper considers the dynamic modelling and motion control of a Surface Effect Ship (SES) for safer transfer of personnel and equipment from vessel to-and-from an offshore wind-turbine. Such a vessel is a key enabling factor for operation and maintenance (O&M) of offshore wind-energy infrastructure. The control system designed is referred to as Boarding Control System (BCS). We investigate the performance of this system for a specific wind-farm service vessel–The Wave Craft. A two-modality vessel model is presented to account for the vessel free motion and motion whilst in contact with a wind-turbine. On a SES, the pressurized air cushion carries the majority of the vessel mass. The control problem considered relates to the actuation of the pressure such that wave-induced vessel motions are minimized. This leads to a safer personnel transfer in developed sea-states than what is possible today. Results for the BCS is presented through simulation and model-scale craft testing.

Microgrid frequency control using multiple battery energy storage system (BESSs)

The work is a report of research on using multiple inverters of Battery Energy Storage Systems with angle droop controllers to share real power in an isolated micro grid system consisting of inertia based Distributed Generation units and variable load. The proposed angle droop control method helps to balance the supply and demand in the micro grid autonomous mode through charging and discharging of the Battery Energy Storage Systems while ensuring that the state of charge of the storage devices is within safe operating conditions. The proposed method is also studied for its effectiveness for frequency control. The proposed control system is verified and its performance validated with simulation software MATLAB/SIMULINK.

Boarding control system for improved accessibility to offshore wind turbines: Full-scale testing

This paper considers the dynamic modelling and motion control of a Surface Effect Ship (SES) for safer transfer of personnel and equipment from vessel to-and-from an offshore wind-turbine. The control system designed is referred to as Boarding Control System (BCS). The performance of this system is investigated for a specific wind-farm service vessel—The Wave Craft. On a SES, the pressurized air cushion supports the majority of the weight of the vessel. The control problem considered relates to the actuation of the pressure such that wave-induced vessel motions are minimized. Results are given through simulation, model- and full-scale experimental testing.

Development of a Rep-inducible, BBTV-based expression system in banana

Banana bunchy top is regarded as the most important viral disease of banana, causing significant yield losses worldwide. The disease is caused by Banana bunchy top virus (BBTV), which is a circular ssDNA virus belonging to the genus Babuvirus in the family Nanoviridae. There are currently few effective control strategies for this and other ssDNA viruses. “In Plant Activation” (InPAct) is a novel technology being developed at QUT for ssDNA virus-activated suicide gene expression. The technology exploits the rolling circle replication mechanism of ssDNA viruses and is based on a unique “split” gene design such that suicide gene expression is only activated in the presence of the viral Rep. This PhD project aimed to develop a BBTV-based InPAct system as a suicide gene strategy to control BBTV. The BBTV-based InPAct vector design requires a BBTV intergenic region (IR) to be embedded within an intron in the gene expression cassette. To ensure that the BBTV IR would not interfere with intron splicing, a TEST vector was initially generated that contained the entire BBTV IR embedded within an intron in a β-glucuronidase (GUS) expression vector. Transient GUS assays in banana embryogenic cell suspensions indicated that cryptic intron splice sites were present within the IR. Transcript analysis revealed two cryptic intron splice sites in the Domain III sequence of the CR-M within the IR. Removal of the CR-M from the TEST vector resulted in an enhancement of GUS expression suggesting that the cryptic intron splice sites had been removed. An InPAct GUS vector was subsequently generated that contained the modified BBTV IR, with the CR-M (minus Domain III) repositioned within the InPAct cassette. Using transient histochemical and fluorometric GUS assays in banana embryogenic cells, the InPAct GUS vector was shown to be activated in the presence of the BBTV Rep. However, the presence of both BBTV Rep and Clink was shown to have a deleterious effect on GUS expression suggesting that these proteins were cytotoxic at the levels expressed. Analysis of replication of the InPAct vectors by Southern hybridisation revealed low levels of InPAct cassette-based episomal DNA released from the vector through the nicking/ligation activity of BBTV Rep. However, Rep-mediated episomal replicons, indicative of rolling circle replication of the released circularised cassettes, were not observed. The inability of the InPAct cassette to be replicated was further investigated. To examine whether the absence of Domain III of the CR-M was responsible, a suite of modified BBTV-based InPAct GUS vectors was constructed that contained the CR-M with the inclusion of Domain III, the CR-M with the inclusion of Domain III and additional upstream IR sequence, or no CR-M. Analysis of replication by Southern hybridisation revealed that neither the presence of Domain III, nor the entire CR-M, had an effect on replication levels. Since the InPAct cassette was significantly larger than the native BBTV genomic components (approximately 1 kb), the effect of InPAct cassette size on replication was also investigated. A suite of size variant BBTV-based vectors was constructed that increased the size of a replication competent cassette to 1.1 kbp through to 2.1 kbp.. Analysis of replication by Southern hybridisation revealed that an increase in vector size above approximately 1.5 - 1.7 kbp resulted in a decrease in replication. Following the demonstration of Rep-mediated release, circularisation and expression from the InPAct GUS vector, an InPAct vector was generated in which the uidA reporter gene was replaced with the ribonuclease-encoding suicide gene, barnase. Initially, a TEST vector was generated to assess the cytotoxicity of Barnase on banana cells. Although transient assays revealed a Barnase-induced cytotoxic effect in banana cells, the expression levels were sub-optimal. An InPAct BARNASE vector was generated and tested for BBTV Rep-activated Barnase expression using transient assays in banana embryogenic cells. High levels of background expression from the InPAct BARNASE vector made it difficult to accurately assess Rep-activated Barnase expression. Analysis of replication by Southern hybridisation revealed low levels of InPAct cassette-based episomal DNA released from the vector but no Rep-mediated episomal replicons indicative of rolling circle replication of the released circularised cassettes were again observed. Despite the inability of the InPAct vectors to replicate to enable high level gene expression, the InPAct BARNASE vector was assessed in planta for BBTV Rep-mediated activation of Barnase expression. Eleven lines of transgenic InPAct BARNASE banana plants were generated by Agrobacterium-mediated transformation and were challenged with viruliferous Pentalonia nigronervosa. At least one clonal plant in each line developed bunchy top symptoms and infection was confirmed by PCR. No localised lesions were observed on any plants, nor was there any localised GUS expression in the one InPAct GUS line challenged with viruliferous aphids. The results presented in this thesis are the first study towards the development of a BBTV-based InPAct system as a Rep-activatable suicide gene expression system to control BBTV. Although further optimisation of the vectors is necessary, the preliminary results suggest that this approach has the potential to be an effective control strategy for BBTV. The use of iterons within the InPAct vectors that are recognised by Reps from different ssDNA plant viruses may provide a broad-spectrum resistance strategy against multiple ssDNA plant viruses. Further, this technology holds great promise as a platform technology for the molecular farming of high-value proteins in vitro or in vivo through expression of the ssDNA virus Rep protein.

Delay-dependent robust H-infinity control for uncertain systems with time-varying delay

This paper proposes a new approach for delay-dependent robust H-infinity stability analysis and control synthesis of uncertain systems with time-varying delay. The key features of the approach include the introduction of a new Lyapunov–Krasovskii functional, the construction of an augmented matrix with uncorrelated terms, and the employment of a tighter bounding technique. As a result, significant performance improvement is achieved in system analysis and synthesis without using either free weighting matrices or model transformation. Examples are given to demonstrate the effectiveness of the proposed approach.

Fear, trust and Aborigines : The historical experience of state institutions and current encounters in the health system

Troubled dynamics between residents of an Aboriginal town in Queensland and the local health system were established during colonisation and consolidated during those periods of Australian history where the policies of 'protection' (segregation), integration and then assimilation held sway. The status of Aboriginal health is, in part, related to interactions between the residents' current and historical experiences of the health and criminal justice systems as together these agencies used medical and moral policing to legitimate dispossession, marginalisation, institutionalisation and control of the residents. The punitive regulations and ethnocentric strategies used by these institutions are within the living memory of many of the residents or in the published accounts of preceding generations. This paper explores current residents' memories and experiences.

Stability analysis and control of multiple converter based autonomous microgrid

In this paper, the stability of an autonomous microgrid with multiple distributed generators (DG) is studied through eigenvalue analysis. It is assumed that all the DGs are connected through Voltage Source Converter (VSC) and all connected loads are passive. The VSCs are controlled by state feedback controller to achieve desired voltage and current outputs that are decided by a droop controller. The state space models of each of the converters with its associated feedback are derived. These are then connected with the state space models of the droop, network and loads to form a homogeneous model, through which the eigenvalues are evaluated. The system stability is then investigated as a function of the droop controller real and reac-tive power coefficients. These observations are then verified through simulation studies using PSCAD/EMTDC. It will be shown that the simulation results closely agree with stability be-havior predicted by the eigenvalue analysis.

Paramedic knowledge of infectious disease aetiology and transmission in an Australian Emergency Medical System

Introduction: Paramedics and other emergency health workers are exposed to infectious disease particularly when undertaking exposure-prone procedures as a component of their everyday practice. This study examined paramedic knowledge of infectious disease aetiology and transmission in the pre-hospital care environment.--------- Methods: A mail survey of paramedics from an Australian ambulance service (n=2274) was conducted.--------- Results: With a response rate of 55.3% (1258/2274), the study demonstrated that paramedic knowledge of infectious disease aetiology and modes of transmission was poor. Of the 25 infectious diseases included in the survey, only three aetiological agents were correctly identified by at least 80% of respondents. The most accurate responses for aetiology of individual infectious diseases were for HIV/AIDS (91.4%), influenza (87.4%), and hepatitis B (85.7%). Poorest results were observed for pertussis, infectious mononucleosis, leprosy, dengue fever, Japanese B encephalitis and vancomycin resistant enterococcus (VRE), all with less than half the sample providing a correct response. Modes of transmission of significant infectious diseases were also assessed. Most accurate responses were found for HIV/AIDS (85.8%), salmonella (81.9%) and influenza (80.1%). Poorest results were observed for infectious mononucleosis, diphtheria, shigella, Japanese B encephalitis, vancomycin resistant enterococcus, meningococcal meningitis, rubella and infectious mononucleosis, with less than a third of the sample providing a correct response.--------- Conclusions: Results suggest that knowledge of aetiology and transmission of infectious disease is generally poor amongst paramedics. A comprehensive in-service education infection control programs for paramedics with emphasis on infectious disease aetiology and transmission is recommended.