Future Electric Systems Research Articles

Present Status and Future Trends in Electric Vehicle Propulsion Technologies

In this paper, the current status and the requirements of primary electric propulsion components-the battery, the electric motors, and the power electronics system-are reviewed. The future trends in the electric propulsion systems, battery charging, and the types of power trains are presented. Possible future electric vehicle powertrain systems based on lithium air battery and plug-in fuel cell vehicles are also discussed.

A cost-benefit analysis of generating electricity from biomass

A key challenge internationally is the design of future electricity systems which will bring about emissions savings and fuel security at least cost. Peat is used to generate electricity in several EU countries, mainly to take advantage of indigenous resources and increase fuel mix diversity. The Irish government has introduced a target of 30% cofiring of peat and biomass by 2015. This paper assesses the feasibility of achieving this target by calculating the available indigenous biomass resource capable of being cofired; the cost of meeting the target; the benefits in terms of carbon abatement; and finally the present value in economic terms of meeting the target. Results demonstrate that Ireland has only half the necessary resource to meet the 30% target and that the net cost of doing so is greater than the cost of what is currently being paid for peat, in all of the scenarios considered. Thus, it is concluded that while it may be technically possible to meet the target by combining national resources with imported biomass this is never the least cost option, and as a result the targeted focus of Government policy may need to be reconsidered.

Performance and Costs of CO2 Capture at Gas Fired Power Plants

This paper summarises the results from a study that assesses the performance and costs of natural gas fired combined cycle power plants with CCS. Information is provided on the designs of each of the plants, their power output, efficiency, greenhouse gas intensity, capital costs, operating and maintenance costs, levelised costs of electricity and costs of CO2 avoidance. Discussion and commentary on the key findings and recommendations is also included. The paper includes information on base load plant performance and costs, but part load performance and costs of operation at low annual capacity factors are also presented because operation at lower load factors may be necessary, particularly in future electricity systems that include high amounts of other low-CO2 generation plants.

The Role of CCS in Power Systems with High Levels of Renewables Penetration

Past studies have used power plant dispatch models with fixed plant portfolios to demonstrate that flexible capture systems may allow operators to increase profits in current electricity markets by increasing plant output at times of high demand. Some of these studies have also speculated that flexible capture systems may be valuable in future electricity systems with high shares of renewable energy as they could allow fossil fuel plants with capture to rapidly respond to changes in residual load. However, few studies have actually examined the role that plants with flexible capture could play in future power systems. Thus, this study examines the role that power generation with flexible capture systems could play in a future European power system where 80% of generation (by energy) is supplied by renewables. The results show that conventional base- and mid-load capacity decreases while the peak-load capacity (i.e., open cycle gas turbines) increases. In European regions with high shares of renewables, the residual load duration curve become steeper, and hourly changes in residual load increase significantly and happen more frequently at low load levels. The shift towards peak capacity and general decrease in load factors places technologies with high capital costs at a relative disadvantage. In the scenario in which CO2 prices reach 650 per tonne CO2 in 2050, approximately one-fifth of the CCS capacity deployed is equipped with flexible capture. However, in a scenario in which CO2 prices reach € 100 per tonne CO2 in 2050, very little capacity is equipped with flexible capture systems as the cost of emitting CO2 offsets the value of flexibility.

An analysis methodology for integrating renewable and nuclear energy into future smart electricity systems

Both renewable energy and nuclear energy are expected to be increasingly and rapidly integrated into future electricity systems in some countries; however, there are still many bottlenecks for their penetration from technological and systematic perspectives. On the other hand, one of the most crucial elements of future electricity systems will be the capability for ‘smart’ controls on both the supply and demand sides to perform under real-time dynamics. Therefore, a methodology was proposed in the present study to analyze the penetration of renewable and nuclear energy into future electricity systems with new added electric devices such as batteries, electric vehicles and heat pumps operated under smart control strategies. The methodology was based on a set of models organized into an input–output framework and actualized using an hour-by-hour computer simulation to achieve a real-time supply–demand balance. The methodology has been developed as a flexible software platform and applied to the Kansai area in Japan. The interactions between the integration of renewable and nuclear energy and operation patterns of new controllable devices were obtained and compared in different scenarios. The feasibility of the proposed methodology has been demonstrated through the scenario analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Integrating wind power using intelligent electric water heating

Dwindling fossil fuel resources and pressures to reduce greenhouse gas emissions will result in a more diverse range of generation portfolios for future electricity systems. Irrespective of the portfolio mix the overarching requirement for all electricity suppliers and system operators is to instantaneously meet demand, to operate to standards and reduce greenhouse gas emissions. Therefore all electricity market participants will ultimately need to use a variety of tools to balance the power system. Thus the role of demand side management with energy storage will be paramount to integrate future diverse generation portfolios. Electric water heating has been studied previously, particularly at the domestic level to provide load control, peak shave and to benefit end-users financially with lower bills, particularly in vertically integrated monopolies. In this paper a number of continuous direct load control demand response based electric water heating algorithms are modelled to test the effectiveness of wholesale electricity market signals to study the system benefits. The results are compared and contrasted to determine which control algorithm showed the best potential for energy savings, system marginal price savings and wind integration.

Integration of PV power into future low-carbon smart electricity systems with EV and HP in Kansai Area, Japan

Abstract Renewable energy – mainly solar power – is expected to be increasingly rapidly integrated into future electricity systems in Japan especially after the Fukushima Nuclear Accident. On the other hand, one of the most crucial elements of future electricity systems will be the capability for “smart” controls on both supply and demand sides to perform under real-time dynamics. Therefore, the purpose of the study is to evaluate the impacts of integrating PV power into future electricity system with electric vehicles (EVs) and heat pumps (HPs) under smart control strategies in Kansai Area, Japan through scenario analysis. The analysis was conducted using a model that is organized into an input–output framework, and actualized using an hour-by-hour computer simulation to derive a real-time supply-demand balance. Electricity system scenarios with different penetration levels of PV power, EV and HP were obtained. The scenario results show that EV and HP are helpful for integrating more PV power by absorbing excess electricity in future smart electricity systems, and the high level penetration of PV power can reduce CO2 emission greatly and effectively. One million EVs and one million HPs can reduce excess electricity by 3 TWh which is 2% of total electricity, and 30 GWp PV can reduce a maximum of 11.6 million tonnes CO2 emissions which are 43% of total CO2 emissions. Finally, the annual and monthly operation patterns of EV and HP are also uncovered in different solar irradiation and temperature situations.

Scenario analysis on future electricity supply and demand in Japan

Under continuing policies of CO2 emissions reduction, it is crucial to consider scenarios for Japan to realize a safe and clean future electricity system. The development plans for nuclear power and renewable energy - particularly solar and wind power - are being reconsidered in light of the Fukushima nuclear accident. To contribute to this, in the present study, three electricity supply scenarios for 2030 are proposed according to different future nuclear power development policies, and the maximum penetration of renewable energy generation is pursued. On the other side of the equation, three electricity demand scenarios are also proposed considering potential energy saving measures. The purpose of the study is to demonstrate quantitatively the technological, economic and environmental impacts of different supply policy selections and demand assumptions on future electricity systems. The scenario analysis is conducted using an input–output hour-by-hour simulation model subject to constraints from technological, economic and environmental perspectives. The obtained installed capacity mix, power generation mix, CO2 emissions, and generation cost of the scenarios were inter-compared and analyzed. The penetration of renewable energy generation in a future electricity system in Japan, as well as its relationship with nuclear power share was uncovered.

Fault location for aircraft distribution systems using harmonic impedance estimation

The demands for ‘more electric aircraft’ will increase the power distribution requirements of future aircraft electrical distribution systems. To increase safety and reduce aircraft maintenance times on the ground, there is also a need for system condition monitoring to quickly identify and locate any electrical faults which may develop. The work presented in this study forms an initial study into the use of power system harmonic impedance measurement for identifying and locating faults within power cables. The method is passive – that is, it does not require the injection of any test signals – and can be embedded into a centralised equipment controller to provide intelligent, real-time diagnostics. The method estimates the harmonic line–line self-impedance at strategic points in the distribution system by measuring load voltage and current at different load distribution points within the network. By combining the harmonic line–line self-impedance estimates the faults can be identified and located within a few cycles. This can, therefore, provide a ‘backup protection’ system, which does not require bus current measurement. It can also provide a measure of the fault location and could therefore be a significant aid to aircraft maintenance. The study derives the theoretical basis of the scheme and provides experimental results from a laboratory prototype to demonstrate the validity of this approach to detect and locate faults within the system.

Simplified Power Converter for Integrated Traction Energy Storage

Electrical energy storage has a significant role to play in improving the performance of future electric traction systems. This paper proposes a new power electronics topology that integrates the energy storage power electronics with those of the inverter drive system. This topology reduces weight and component count compared with previous topologies but still allows the use of standard machines. Practical results from a laboratory test system are shown, and indicative energy savings for a full-sized system are presented. A study on a City Class Tram on the public transportation system in Blackpool, U.K., shows that clear energy savings may be made by employing ultracapacitor energy storage with the proposed topology.

Electricity market auction settings in a future Danish electricity system with a high penetration of renewable energy sources – A comparison of marginal pricing and pay-as-bid

The long-term goal for Danish energy policy is to be free of fossil fuels through the increasing use of renewable energy sources (RES) including fluctuating renewable electricity (FRE). The Danish electricity market is part of the Nordic power exchange, which uses a Marginal Price auction system (MPS) for the day-ahead auctions. The market price is thus equal to the bidding price of the most expensive auction winning unit. In the MPS, the FRE bid at prices of or close to zero resulting in reduced market prices during hours of FRE production. In turn, this reduces the FRE sources’ income from market sales. As more FRE is implemented, this effect will only become greater, thereby reducing the income for FRE producers. Other auction settings could potentially help to reduce this problem. One candidate is the pay-as-bid auction setting (PAB), where winning units are paid their own bidding price. This article investigates the two auction settings, to find whether a change of auction setting would provide a more suitable frame for large shares of FRE. This has been done with two energy system scenarios with different shares of FRE. From the analysis, it is found that MPS is generally better for the FRE sources. The result is, however, very sensitive to the base assumptions used for the calculations.

The Future Renewable Electric Energy Delivery and Management (FREEDM) System: The Energy Internet

This paper presents an architecture for a future electric power distribution system that is suitable for plug-and-play of distributed renewable energy and distributed energy storage devices. Motivated by the success of the (information) Internet, the architecture described in this paper was proposed by the NSF FREEDM Systems Center, Raleigh, NC, as a roadmap for a future automated and flexible electric power distribution system. In the envisioned “Energy Internet,” a system that enables flexible energy sharing is proposed for consumers in a residential distribution system. The key technologies required to achieve such a vision are presented in this paper as a result of the research partnership of the FREEDM Systems Center.

A Feasibility Study on a Future Zero-Carbon Electricity System Based on 100% Nuclear Power in Japan

The realization of a zero-carbon electricity system is of vital importance to CO2 reduction in an energy system, and nuclear power is expected to contribute to this much more than the intermittent, complicated, and costly renewable energy in the future in Japan. Therefore, in the present study, a future zero-carbon electricity system based on 100% nuclear power was proposed in Japan. The feasibility of the system was studied in terms of the reliability of fluctuations of both the daily and seasonal electricity demand and supply using an hour-by-hour computer simulation. The simulation provided a detailed system design and real-time operation information for the electricity system based on hourly data series of electrical load, nuclear power output, and electricity storage. The obtained results show that the proposed nuclear-powerbased zero-carbon electricity system is technologically feasible with the help of EV batteries and hydrogen for daily and seasonal electricity storage, respectively, and smart control technologies are necessary to operate the whole system. Finally, key issues relating to the implementation of such a system were discussed to highlight the need for continued research.

Exploring the hypothetical limits to a nuclear and renewable electricity future

This article evaluates whether the world can transition to a future global electricity system powered entirely by nuclear power plants, wind turbines, solar panels, geothermal facilities, hydroelectric stations, and biomass generators by 2030. It begins by explaining the scenario method employed for predicting future electricity generation, drawn mostly from tools used by the International Energy Agency. The article projects that the world would need to build about 7744 Gigawatts (GW) of installed electricity capacity by 2030 to provide 37.2 thousand terawatt-hours (TWh). Synthesizing data from the primary literature, the article argues that meeting such a projection with nuclear and renewable power stations will be difficult. If constructed using commercially available and state-of-the-art nuclear and renewable power stations today, the capital cost would exceed $40 trillion, anticipated negative externalities would exceed $1 trillion per year, and immense strain would be placed on land, water, material, and human resources. Even if nuclear and renewable power technologies were much improved, trillions of dollars of investment would still be needed, millions of hectares of land set aside, quadrillions of gallons of water used, and material supplies of aluminum, concrete, silicon, and steel heavily utilized or exhausted. Because of these constraints, the only true path towards a more sustainable electricity system appears to be reducing demand for electricity and consuming less of it. Copyright © 2009 John Wiley & Sons, Ltd.

Alteration of the Let-off and Take-up Machine of Loom SAURER 400

At present, many shuttleless looms in Chinese enterprises still use the mechanical let-off and take-up machine, and to fulfill the requirements of modern textile technology and consider the factor of saving cost, most enterprises begin to alter their old looms. Taking the rapier loom SAURER400 as the research object, the original let-off and take-up machine of loom SAURER400 was analyzed in the article, and the electric let-off and take-up system was designed, and the revs of the let-off input end and the take-up input end were respectively computed, which could provide some references for the alteration of future electric let-off and take-up control system.

Recent advances in nuclear powered electric propulsion for space exploration

Nuclear and radioisotope powered electric thrusters are being developed as primary in space propulsion systems for potential future robotic and piloted space missions. Possible applications for high-power nuclear electric propulsion include orbit raising and maneuvering of large space platforms, lunar and Mars cargo transport, asteroid rendezvous and sample return, and robotic and piloted planetary missions, while lower power radioisotope electric propulsion could significantly enhance or enable some future robotic deep space science missions. This paper provides an overview of recent US high-power electric thruster research programs, describing the operating principles, challenges, and status of each technology. Mission analysis is presented that compares the benefits and performance of each thruster type for high priority NASA missions. The status of space nuclear power systems for high-power electric propulsion is presented. The paper concludes with a discussion of power and thruster development strategies for future radioisotope electric propulsion systems.

A Power Modeling and Optimization Scheme for Future Ultra Small Size Electric Systems

Accompanying with the rapid popularization of portable equipments, it becomes very important to make the battery lifetime longer without increasing the battery size. Especially toward the ubiquitous computing age, long battery lifetime in a tight size limitation will be highly demanded. It will be invaluable for intelligent sensor for cars and robots, too. This paper proposes an algorithm to optimize the battery lifetime in the restriction of total size, by simultaneous analysis of operation condition of battery, buck converter, and LSI. We discuss accurate design models of those components at the same time.

More comfort less consumption

The 42 V debate has prompted AFL to think about future electrical systems and effective energy management. As early as in 2000, together with Audi, design targets for electrical system management were defined. Departing from the industry focus on hybrid but inflexible 42/14V systems, AFL has developed solutions for a flexible, demand-responsive voltage supply. This so-called micro-hybrid power management strategy allows a higher system voltage at lower costs

Study on voltage regulation methods for distribution systems with dispersed generators

AbstractConnection of a large number of the dispersed generators to distribution networks is not easy due to various technical considerations. Thus, we have been trying to devise a concept for future electrical distribution systems with many dispersed generators. In this work, it has been considered that each customer's load and each generator's active and reactive power should be controlled in order to stabilize and optimize the networks. Under this consideration, two control methods for future distribution systems are proposed, a cooperative control and an independent control. We have confirmed experimentally that the voltage regulation ability is higher with the cooperative control than with the independent control, especially in cases of an eccentric load profile in a feeder and a heavy load. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 154(4): 16–23, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20246

Optimal Planner for Spacecraft Formations in Elliptical Orbits

An optimal planner for spacecraft formations in elliptical reference orbits is presented. A fast solution to an individual spacecraft minimum time or fuel maneuver using the Hamilton-Jacobi-Bellman formulation is developed using spline approximations to evaluate thrust effect integrals. The individual optimal spacecraft maneuvers use realistic low-thrust, bounded inputs similar to future electric propulsion systems. A formation optimal planner is then formulated using the individual spacecraft maneuvers as a basis. The formulation is easily scalable to larger clusters, provably optimal over the formation, and numerically robust; it also requires minimal communication between fleet members. An example is presented of a tetrahedron formation in a highly elliptical reference orbit (e = 0.8), with solutions to both formation minimum-time and minimum-fuel problems given. Comparison with linear programming techniques show a distinct savings in fuel usage for high-eccentricity examples.