Control Algorithm for Parallel Connected Offshore Wind Turbine Generators

A control algorithm for Parallel Connected Offshore Wind Turbines with permanent magnet synchronous Generators (PCOWTG) is presented in this paper. The algorithm estimates the optimal collective speed of turbines based on the estimated mechanical power of wind turbines without direct measurement of wind speed. In the proposed topology of the wind farm, direct-drive Wind Turbine Generators (WTG) is connected to variable low-frequency AC Collection Grids (ACCG) without the use of individual power converters. The ACCG is connected to a variable low-frequency offshore AC transmission grid using a step-up transformer. In order to achieve optimum wind power extraction, the collective speed of the WTGs is controlled by a single onshore Back to Back converter (B2B). The voltage control system of the B2B converter adjusts voltage by keeping a constant Volt/Hz ratio, ensuring constant magnetic flux of electromagnetic devices regardless of changing system frequency. With the use of PI pitch compensators, wind power extraction for each wind turbine is limited within rated WTG power limits. Lack of load damping in offshore wind parks can result in oscillatory instability of PCOWTG. In this paper, damping torque is increased using P pitch controllers at each WTG that work in parallel with PI pitch compensators

SMART ROVLATIS: flexible survey platform for surface and Uunderwater operations

This paper describes a novel vehicle designed for operation flexibility in high-resolution near seabed survey from shallow inshore waters out to the continental shelf edge. The vehicle can be operated in surface tow or as a thrusted pontoon. With buoyancy module release the vehicle becomes neutrally buoyant and is operated as a survey class remotely operated vehicle (ROV) depth rated to 1,000m. Special features of the system include: deployment interoperability for small inshore boats and larger research vessel; fault tolerant thruster control; novel high frequency short range sonar; onboard computer control enabling real-time disturbance reaction; topside augmented reality system support. The paper includes test results from the off shore sea trials with the ROVLATIS in March 2009

Development and integration of a novel IP66 Force Feedback Joystick for offshore operations

Intervention activities in underwater environments are of great importance in many areas, such as the exploration, monitoring and documentation of sea resources, historical treasures or industrial applications. The use of robotic systems and automatic procedures is becoming fundamental, since the work conditions for divers are risky and often unfeasible, and several kind of works are every way impossible for humans. One of the most important objectives of the underwater robotic research consists in making technological systems friendly and easy to use by all kind of experts. This paper presents the development and test of a Force Feedback (FFB) Joystick aimed at supporting ROVs pilots during their work. Reaction forces on the joystick axes, based on specific error parameters, let the pilot understand in real-time the underwater environment where the robot is moving and thruster velocity saturation limits, thus improving significantly the efficiency of the given mission. The present work describes the design, assembly and programming of the joystick, and its test within a virtual environment simulating the real time control of Internet-enabled smart ROVs operating in remote locations. Results obtained with this kind of applications are discussed, and potentiality of the systems are underlined for future developments

Independent Tether Management Nodes for Subsea Vehicles in Complex Fields

This paper presents a Tether Multipoint Management System (TMMS) for a Resident Remotely Operated Vehicle (ROV) in offshore operations. Operating close to structure or seabed. Boulders etc tether management is critical to ensure the safety and effectiveness of operations without tether entanglement. The proposed TMMS is composed of one or more Independent Tether Management Nodes (ITMN) enabling the ROV to move freely and autonomously around offshore structures while minimizing the risk of tether entanglement. The ITMN can use a combination of active thrusters (axial, lateral, and vertical) and passive (buoyancy and fin) control to achieve the necessary degrees of freedom and an onboard battery for power. The proposed system expands the operational capability of the ROV, allowing it to perform tasks not possible beforehand, saving time and increasing efficiency. </p

Preliminary study of a novel magnetic sensor for safety in industrial robotics

In this paper a novel magnetic sensor for industrial robotics is presented. The main aim of the sensor is to detect the presence of human beings in order to avoid the collision between workers and the robot. The sensor consists in such an artificial skin to conform at the robot shape, made by several turns of a wire covered by a dielectric. The sensor made in this way has no exposed metal parts, so it is safe from an electrical point of view and has no tips that could be caught up by surrounding objects. This sensor in mainly based to the magnetic field variation due to the presence of the target. At first, a laboratory prototype of this sensor was built to perform a preliminary set of measurements. Furtherly a prototype implementation was realized and tested in a realistic scenario

Robotic Ship Hull Inspection For Damage Repair

In this paper, we investigate the methods to be used in the inspection of damaged ship hulls in water at sea, as part of the European Union (EU) Robotic Survey, Repair and Agile Manufacture (RESURGAM) Project. Employing underwater robotics equipped with camera or laser sensors, along with robust control and positioning systems, 3D models of the damaged section(s) can be produced with a goal of providing sufficientinformation for the subsequent design of repair patch(es), and ultimately the application of this repair to the ship. This work will allow damaged ships at sea to seek repair without the need for access to a dry dock. Preliminary results from recent field operations are included in this paper, with further field research to be carried out later this year.</p