Electrical System Integration Research Articles

Energy homeostasis model for electrical and thermal systems integration in residential buildings: a means to sustain distributed generation systems integration

Energy homeostasis model for electrical and thermal systems integration in residential buildings: a means to sustain distributed generation systems integration

Special issue on all‐electric and hybrid‐electric flight

Special issue on all‐electric and hybrid‐electric flight

Current status and grand challenges for small wind turbine technology

Abstract. While modern wind turbines have become by far the largest rotating machines on Earth with further upscaling planned for the future, a renewed interest in small wind turbines (SWTs) is fostering energy transition and smart grid development. Small machines have traditionally not received the same level of aerodynamic refinement as their larger counterparts, resulting in lower efficiency, lower capacity factors, and therefore a higher cost of energy. In an effort to reduce this gap, research programs are developing worldwide. With this background, the scope of the present study is 2-fold. In the first part of this paper, an overview of the current status of the technology is presented in terms of technical maturity, diffusion, and cost. The second part of the study proposes five grand challenges that are thought to be key to fostering the development of small wind turbine technology in the near future, i.e. (1) improving energy conversion of modern SWTs through better design and control, especially in the case of turbulent wind; (2) better predicting long-term turbine performance with limited resource measurements and proving reliability; (3) improving the economic viability of small wind energy; (4) facilitating the contribution of SWTs to the energy demand and electrical system integration; (5) fostering engagement, social acceptance, and deployment for global distributed wind markets. To tackle these challenges, a series of unknowns and gaps are first identified and discussed. Based on them, improvement areas are suggested, for which 10 key enabling actions are finally proposed.

Electrical and Energy Systems Integration for Maritime Environment-Friendly Transportation

The policies against climate change require the reduction of greenhouse gas emissions of marine transportation. To reach the planned goals, the most promising approach is working both on ships improvement and ports redesign. The latter must enable the new green ships supply with sustainable electrical energy, by integrating shore connection systems, local renewables, and energy storage systems. In this paper, a methodology to obtain such an objective is proposed, capable of taking into account both ships’ and ports’ characteristics. The methodology workflow is explained through a case study, where two shore connection power sizes and two different operative approaches for recharging the ship onboard energy storage are considered. A discussion about the most suitable energy storage technologies is also provided. The case study shows how the methodology can be applied, as well as demonstrating that the port infrastructure has a direct effect on the ship environmental performance.

The evolution of interstate power grid formation

This study analyzes the process of electric power system integration in various regions worldwide. This process is implemented by creating both interstate electric ties and power grids. The analysis is comprehensive and examines the system, spatial, technical, organizational, and market aspects of the integration. Various countries, including developed countries such as Europe and North America, as well as economically developing countries such as Central America and Africa, are involved in this process. However, the rates and scales of electric power integration differ across various regions worldwide. The analysis shows that the process of electric power integration, which has decades of history, is still ongoing, despite the growth of other trends, such as the development of distributed generation. Further electricity integration is expected to lead to the formation of a global power interconnection in the long term.

The curtailment paradox in the transition to high solar power systems

Summary Rising penetrations of variable renewable energy (VRE) in power systems are expected to increase the curtailment of these resources because of oversupply and operational constraints. We evaluate the effect on curtailment from various flexibility approaches, including storage, thermal generator flexibility, operating reserve eligibility rules, transmission constraints, and temporal resolution, by using a highly resolved realistic system. Results reveal two aspects of a curtailment paradox as the system evolves to higher solar penetration levels. First, thermal generator parameters, especially in restricting minimum operating levels and ramp rates, affect VRE curtailment more in mid-PV penetration levels (∼25%–40%) but much less at lower (∼20%) or higher (∼45%) PV penetration levels. Second, although allowing VRE and storage to provide operating reserve results in significant operating costs and curtailment benefits, the price suppression effect from these resources reduces incentives for PV to provide operating reserves with curtailed energy.

Necessity and Targets of Future Electric Power System Simulation and Integration Studies for Realizing Higher Variable Renewable Energy Deployment and Lower CO2-Emission Society

Necessity and Targets of Future Electric Power System Simulation and Integration Studies for Realizing Higher Variable Renewable Energy Deployment and Lower CO2-Emission Society

Improved energy supply for non-road electric vehicles by occasional charging station location modelling

Electric mobility has significantly changed perspectives in the mobility sector. Major challenges require the efficient design of systems energy consumption and supply, so that developments focus on battery related improvements such as charging infrastructure integration, recharge process optimisation, battery technology and cost reductions. The concept of occasional recharging is to provide additional usable battery energy to the system without additional disturbance of processes, while using existing process sequences and process interruptions in optimised infrastructure allocations.Existing models for charging infrastructure allocation to target at maximal demand coverage being determined by vehicles' range demand. Electric supply system integration for occasional battery charging showed the necessity to change the existing demand coverage definition, so that material handling process characteristics include potentials for system adaptions and increased efficiency as alternative demand to be covered. This innovative approach changes the perspective on demand coverage to present a potential within existing processes instead of an additional effort and addresses the shortcomings and recommendations of existing research approaches for an endogenous covering distance, more detailed and precise energy consumption values and the integration of real process information.Case study investigations showed increased Usable Battery Energy of +40% to +60% and the allocation improvement based on the innovative framework.

A High-Efficiency Wind Energy Harvester for Autonomous Embedded Systems.

Energy harvesting is currently a hot research topic, mainly as a consequence of the increasing attractiveness of computing and sensing solutions based on small, low-power distributed embedded systems. Harvesting may enable systems to operate in a deploy-and-forget mode, particularly when power grid is absent and the use of rechargeable batteries is unattractive due to their limited lifetime and maintenance requirements. This paper focuses on wind flow as an energy source feasible to meet the energy needs of a small autonomous embedded system. In particular the contribution is on the electrical converter and system integration. We characterize the micro-wind turbine, we define a detailed model of its behaviour, and then we focused on a highly efficient circuit to convert wind energy into electrical energy. The optimized design features an overall volume smaller than 64 cm. The core of the harvester is a high efficiency buck-boost converter which performs an optimal power point tracking. Experimental results show that the wind generator boosts efficiency over a wide range of operating conditions.

Engineer’s Trainninngu Program of JR East Tokyo Electric Construction & System Integration Office

Engineer’s Trainninngu Program of JR East Tokyo Electric Construction & System Integration Office

Flexible Vertical Light Emitting Diodes

Strategies are presented to achieve ultrathin light-emitting diodes using the technique of epitaxial liftoff in ways that protect the materials from the etchants used for release and tether the devices to the underlying wafer for subsequent transfer printing onto substrates of interest. The results lead to an advanced interconnection scheme and vertical device layout that facilitate electrical contacts and system integration on flexible substrates.

VHDL-AMS to Support DAE-PDE Coupling and Multilevel Modeling

With the increasingly high level of electrical system integration, the modeling of both the system behavior and the detailed physics of its elements becomes necessary. VHDL-AMS language allows to describe a range of physical systems, such as electro-magnetic devices, using a unified design approach to simulate a complete system. In addition, the most important constraint in the hierarchical modeling of the design cycle is the difficulty to use the same language or tool for the whole modeling steps and define a single set of tests for each description level. VHDL-AMS can be used as unified language for multilevel modeling, but it cannot support the description of some physical phenomena such local ones. The aim of the paper is to achieve the behavioral and the detailed modeling of multiple energy domains using VHDL-AMS, and their integration in the system environment. It proposes solutions to extend the computation capability of this language, based on computer-aided coupling strategies.

Electrical System Integration, Electromagnetic Compatibility (EMC) Interface Management of Railway Electrification Systems

This paper outlines the considerations and issues that need to be addressed to ensure that railway electrical systems are integrated successfully. An overview of systems integration in the railway environment is given. Electromagnetic Compatibility (EMC) is identified as a major component in the systems integration process. The method of demonstrating EMC for railway electrical systems is reviewed. Procedures to control stray current are outlined and the management of the DC/AC interface is examined. Finally the important issue of a systems approach to Earthing Management of both AC and DC railways are summarised.

DEVELOPMENT OF HUMANOID ROBOT PLATFORM KHR-2 (KAIST HUMANOID ROBOT 2)

The mechanical and electrical system designs and system integration including controllers and sensory devices of the humanoid KHR-2 are presented. The design concept and the objective are also discussed. Since 2003, we have been developing KHR-2, which has 41 DOF (degrees of freedom). Each arm of KHR-2 has 11 DOF in total: 5 DOF/hand (i.e. fingers), 2 DOF/wrist, and 4 DOF/arm. Each leg constitutes 6 DOF. The head constitutes 6 DOF (2 DOF for eyes and 2 DOF at the neck), and the trunk has 1 DOF. KHR-2 has been mechanically designed to have a human friendly appearance and also wide ranges of angular motion. Its joint actuators have been designed in order to reduce motion uncertainties such as backlash. All axes of KHR-2 are under distributed control, which reduces the computational burden on the main controller and also to facilitate device expansions. We have developed a microprocessor-based sub-controller for servo motor operations, onto which sensory feedback is interfaced. The main controller, which is mounted on the back of the robot communicates with sub-controllers in real-time through CAN (Controller Area Network). Windows XP is used as the OS (Operating System), which enables rapid program development. RTX (Real Time eXtension) HAL extension software is used to realize the real-time control in the Windows XP environment. KHR-2 has several sensor types such as 3-axis F/T (Force/Torque) sensors at the foot and wrist, an inertia sensor system (accelerometer and rate gyro), and a CCD camera. The F/T sensor at the foot is crucially important for stable walking. The inertia sensor system is essential for determining the inclination of the robot with respect to the ground.

Status of the United States Air Force's More Electric Aircraft initiative

Since the early 1990's, the USAF has been successfully pursuing advancement in aircraft electrical power system technologies as a means of collectively establishing the capability to reduce dramatically or eliminate centralized hydraulics aboard aircraft and replace them with electrical power as the motive force for all aircraft functions. This overall approach (called the More Electric Aircraft, MEA) has been analytically determined to provide dramatic improvements in reliability, maintainability, supportability and operations/support cost as well as enhancements in aircraft weight, volume, and battle-damage reconfigurability. A time- and technology availability-phased research and development program has been structured to demonstrate the required electrical component and subsystems performance to allow equivalent or improved aircraft performance over the use of hydraulic power. This paper provides: (1) a brief historical treatment of technology milestones achieved which enabled the MEA approach; (2) a status of USAF and DoD research and development programs in electrical power generation, distribution, energy storage, systems integration and flight testing; (3) a description of some of the USAF's planned demonstration activities in aircraft electrical power subsystems; and (4) the dual use nature of many of these technologies enabling a variety of electric and hybrid electrically-propelled military weapon systems and commercial vehicles.

Development of arcjet and ion propulsion for spacecraft stationkeeping

Near term flight applications of arcjet and ion thruster satellite station-keeping systems as well as development activities in Europe, Japan, and the United States are reviewed. At least two arcjet and three ion propulsion flights are scheduled during the 1992–1995 period. Ground demonstration technology programs are focusing on the development of kW-class hydrazine and ammonia arcjets and xenon ion thrusters. Recent work at NASA Lewis Research Center on electric thruster and system integration technologies relating to satellite stationkeeping and repositioning will also be summarized.