Peter N. Green

Voltage sag detection technique for a dynamic voltage restorer

Dynamic voltage restorers (DVRs) are used to protect sensitive loads from the effects of voltage sags on the distribution feeder. This paper presents and verifies a novel voltage sag detection technique for the control system of a DVR. In some cases it may be necessary for the DVR control system to not only detect the start and end of a voltage sag but also to determine the sag depth and any associated phase shift. The DVR, which is placed in series with a sensitive load, must be able to respond quickly to a voltage sag if end users of sensitive equipment are to experience no voltage fluctuations. A problem arises when fast evaluation of these parameters is required, as standard information tracking or detection methods such as the Fourier transform or phase-locked-loop (PLL) are too slow. As a result of this the voltage sag detection method this paper proposes a new state-space matrix method, which is able to compute the phase shift and voltage reduction of the supply voltage much quicker than the Fourier transform or a PLL. The paper also illustrates that the state space matrix method returns results that can be directly interpreted whereas other methods such as the wavelet transform, which return results that can be difficult to interpret.

Wireless sensor networks for industrial processes

The paper describes our work to explore the use of wireless sensor networks for industrial processes. Long term challenges including communication in a hostile environment, ad hoc networking, computing platforms, process imaging, sensing, miniaturization, compliance, micro-electromechanical systems and power harvesting are introduced. The issues are generic for applications to industrial process but the present work is targeted at monitoring grain storage. One requirement is to provide estimates of local position in a vessel and the paper describes progress towards using RF signal strength in the network for this purpose.

An Underwater Robotic Network for Monitoring Nuclear Waste Storage Pools

Nuclear power provides a significant portion of our current energy demand and is likely to become more wide spread with growing world population. However, the radioactive waste generated in these power plants must be stored for around 60 years in underwater storage pools before permanent disposal. These underwater storage environments must be carefully monitored and controlled to avoid an environmental catastrophe. In this paper, we present an underwater mobile sensor network that is being developed to monitor these waste storage pools. This sensing system will also be used in very old storage pools to build maps of their internal structure which can then be used for waste removal and pool decommissioning. In this paper, we outline the unique challenges of our application scenario which include robot localization in cluttered underwater environments and the effect of location errors on environment mapping. We also list other industrial applications that can benefit from our underwater sensor network.

Propulsion systems for micro-Autonomous Underwater Vehicles (μAUVs)

The development of small-scale sensor platforms for the internal monitoring of aqueous processes creates a range of challenges in terms of the provision of mobility. De-coupled x-y plane and z-axis movement, the need for low power consumption and a minimum of 4 degrees of freedom means that the suitability of conventional propulsion systems needs to be investigated. This paper presents a brief summary and comparison of the available propulsion options. Propellers have been chosen as the best means of propulsion and a novel approach to modeling and selection of both motors and propellers is given. The thruster configuration and initial mechanical designs for a μAUV are also outlined.

The Mechatronic Design of a Micro-Autonomous Underwater Vehicle

Micro-autonomous underwater vehicles (μAUVs) can form the basis of mobile underwater sensor networks for monitoring sub-surface cluttered environments. There are numerous technical challenges involved in constructing such vehicles using off-the-shelf components. This paper presents progress to date in the design of such a system, the problems encountered and possible solutions.

The design and technical challenges of a micro-autonomous underwater vehicle (μAUV)

Micro-Autonomous Underwater Vehicles (μAUVs) can form the basis of mobile underwater sensor networks for monitoring sub-surface cluttered environments. There are numerous technical challenges involved in constructing such vehicles using off-the-shelf components. This paper presents progress to date in the design of such a system, the problems encountered and possible solutions.

A de-coupled vertical controller for micro-autonomous underwater vehicles (μAUVs)

Micro-Autonomous Underwater Vehicles (μAUVs) can be used as part of underwater sensor networks in to monitor industrial processes. The high manoeuvrability requirements dictate that traditional AUV designs are not suitable. A prototype μAUV has been developed with independent movement capabilities in the horizontal and vertical planes. This paper outlines the work conducted on the design of a vertical control system and analyses the difference between the simulation and real-world implementation.

Design considerations for Micro-Autonomous Underwater Vehicles (μAUVs)

Mobile Underwater Sensor Networks provide an attractive solution to the problem of obtaining measurements from within liquid-based industrial processes. Most underwater vehicles are aimed at oceanographic applications and are therefore too large to be used in comparatively small processes. This paper sets out the design considerations for the development of a Micro-Autonomous Underwater Vehicle (??AUV) for use in a process environment.

Depth control for micro-autonomous underwater vehicles (μAUVs): Simulation and experimentation

Swarms of micro-autonomous underwater vehicles (μAUVs) are an attractive solution to the problem of nuclear storage pond monitoring. Independent movement in the horizontal and vertical planes is necessary to maximize manoeuvrability. This paper presents a comparison of different control strategies for independent depth control using both simulations and real experimental results. PID, sliding mode and a simplification of sliding mode (called ‘bounded PD’) are simulated using a MATLAB/SIMULINK model and are then compared to experimental results obtained when the controllers were implemented on a prototype μAUV.

Environmental monitoring in grain

It is shown that Wireless Sensor Networks (WSNs) are capable of deployment in industrial processes which present particularly hostile RF environments. The techniques which have been developed have generic applicability, but in this work they are focused on the monitoring of grain storage. Determination of the environmental conditions in a grain silo is challenged by the dielectric properties of the grain and the multi-path nature of RF propagation in the silo. These challenges apply to both the inter-node WSN communication and node positioning. The methods adopted to meet these challenges and significant results achieved are presented.