Geraint Bevan

Bio: Geraint Bevan is an academic researcher from Glasgow Caledonian University. The author has contributed to research in topics: Fault (power engineering) & Wind power. The author has an hindex of 7, co-authored 28 publications receiving 412 citations. Previous affiliations of Geraint Bevan include University of Glasgow.

Bond-graph modeling

Abstract: The bond-graph method is a graphical approach to modeling in which component energy ports are connected by bonds that specify the transfer of energy between system components. Power, the rate of energy transport between components, is the universal currency of physical systems. Bond graphs are inherently energy based and thus related to other energy-based methods, including dissipative systems and port-Hamiltonians. This article has presented an introduction to bond graphs for control engineers. Although the notation can initially appear daunting, the bond graph method is firmly grounded in the familiar concepts of energy and power. The essential element to be grasped is that bonds represent power transactions between components

Trajectory generation for road vehicle obstacle avoidance using convex optimization

Abstract: This paper presents a method for trajectory generation using convex optimization to find a feasible, obstacle-free path for a road vehicle. Consideration of vehicle rotation is shown to be necessary if the trajectory is to avoid obstacles specified in a fixed Earth axis system. The paper establishes that, despite the presence of significant non-linearities, it is possible to articulate the obstacle avoidance problem in a tractable convex form using multiple optimization passes. Finally, it is shown by simulation that an optimal trajectory that accounts for the vehicle's changing velocity throughout the manoeuvre is superior to a previous analytical method that assumes constant speed.

Review of Energy Storage Systems in electric grid and their potential in distribution networks

Abstract: Concerns over changes to the global environment and the growing need for energy have increased the penetration of renewable energy (RE) generation into low voltage distribution networks. The introduction of Energy Storage Systems (ESS) into distribution networks has been proposed to improve the reliability and performance of power systems. Energy storage systems will also be important in helping to regulate the supply from intermittent RE sources that feed into variable load demand. The focus of this paper is to provide an overview of the state of the art of ESS, concentrating on the distinct characteristics and applications of the different types. The analysis includes comparison and evaluation of different storage preferences with regard to integration of these technologies with an electric grid at the distribution network level that may lead to benefits such as distribution upgrade deferral and improvements in power quality and reliability.

Sliding mode control of wind energy conversion systems: Trends and applications

Abstract: Motivated by the increasing concerns over environmental challenges such as global warming and exhaustion of fossil-fuel reserves, the renewable energy industry has become the most sought-after source of electrical energy production worldwide. In this context, wind energy conversion systems (WECS) are one of the most dominant and fastest-growing technologies, playing an increasingly vital role in renewable power generation. To meet this growing demand and mitigate the vulnerability of WECS to various sets of internal/external faults, the cost-effectiveness and efficient power production of WECS must be ensured, which highlights the critical role of the control system. This topic has been intensively studied in the literature, and many control approaches have been developed to deal with the simultaneous enhancement of efficiency and reliability of WECS. However, sliding mode control (SMC) has proved its reliable and superior performance among most control strategies due to its inherent robustness to parametric uncertainties and disturbances and ease of design and implementation. Accordingly, this paper provides a comprehensive survey of existing literature on the application of SMC and its emerging modifications to address different control design problems for WECS.

Path Planning and Tracking for Vehicle Collision Avoidance Based on Model Predictive Control With Multiconstraints

Abstract: A path planning and tracking framework is presented to maintain a collision-free path for autonomous vehicles. For path-planning approaches, a 3-D virtual dangerous potential field is constructed as a superposition of trigonometric functions of the road and the exponential function of obstacles, which can generate a desired trajectory for collision avoidance when a vehicle collision with obstacles is likely to happen. Next, to track the planned trajectory for collision avoidance maneuvers, the path-tracking controller formulated the tracking task as a multiconstrained model predictive control (MMPC) problem and calculated the front steering angle to prevent the vehicle from colliding with a moving obstacle vehicle. Simulink and CarSim simulations are conducted in the case where moving obstacles exist. The simulation results show that the proposed path-planning approach is effective for many driving scenarios, and the MMPC-based path-tracking controller provides dynamic tracking performance and maintains good maneuverability.

The Behavioral Approach to Open and Interconnected Systems

Abstract: In this article we have presented an approach to the mathematical description of dynamical systems. The central notion is the behavior, which consists of the set of time trajectories that are declared possible by the model of a dynamical system. Often, the behavior is defined as the set of solutions of a system of differential equations. Models that specify a behavior usually involve latent variables in addition to the manifest variables the model aims at. We have also described a methodology for modeling interconnected systems, called tearing, zooming, and linking. The underlying mathematical language consists of terminals, modules, the interconnection graph, the module embedding, and the manifest variable assignment. The combination of module equations, interconnection constraints, and manifest variable assignment leads to a latent-variable representation for the behavior of the manifest variables the model aims. This methodology of tearing, zooming, and linking offers a systematic procedure for modeling interconnected systems that is much better adapted to the physics of interconnected systems than input/output-modeling procedures such as, for example, Simulink. The methodology of tearing, zooming, and linking has many things in common with bond graphs.

Algorithms for collision-free navigation of mobile robots in complex cluttered environments: a survey

Abstract: We review a range of techniques related to navigation of unmanned vehicles through unknown environments with obstacles, especially those that rigorously ensure collision avoidance (given certain assumptions about the system). This topic continues to be an active area of research, and we highlight some directions in which available approaches may be improved. The paper discusses models of the sensors and vehicle kinematics, assumptions about the environment, and performance criteria. Methods applicable to stationary obstacles, moving obstacles and multiple vehicles scenarios are all reviewed. In preference to global approaches based on full knowledge of the environment, particular attention is given to reactive methods based on local sensory data, with a special focus on recently proposed navigation laws based on model predictive and sliding mode control.

Overview of energy storage systems in distribution networks: Placement, sizing, operation, and power quality

Abstract: The deployment of energy storage systems (ESSs) is a significant avenue for maximising the energy efficiency of a distribution network, and overall network performance can be enhanced by their optimal placement, sizing, and operation. An optimally sized and placed ESS can facilitate peak energy demand fulfilment, enhance the benefits from the integration of renewables and distributed energy sources, aid power quality management, and reduce distribution network expansion costs. This paper provides an overview of optimal ESS placement, sizing, and operation. It considers a range of grid scenarios, targeted performance objectives, applied strategies, ESS types, and advantages and limitations of the proposed systems and approaches. While batteries are widely used as ESSs in various applications, the detailed comparative analysis of ESS technical characteristics suggests that flywheel energy storage (FES) also warrants consideration in some distribution network scenarios. This research provides recommendations for related requirements or procedures, appropriate ESS selection, smart ESS charging and discharging, ESS sizing, placement and operation, and power quality issues. Furthermore, this study identifies future research opportunities in relation to challenges for optimal ESS placement planning, development and implementation issues, optimisation techniques, social impacts, and energy security.