Hybrid Electric Power System Research Articles

Improvement of ultracapacitors-energy usage in fuel cell based hybrid electric vehicle

Hybrid electric power systems based on fuel cell stack and energy storage sources like batteries and ultracapacitors are a plausible solution to vehicle electrification due to their balance between acceleration performance and range. Having a high degree of hybridization can be advantageous, considering the different characteristics of the power sources. Some parameters to be considered are: specific power and energy, energy and power density, lifetime, cost among others. Ultracapacitors (UC) are of particular interest in electric vehicle applications due to its high-power capability, which is commonly required during acceleration. UCs are commonly used without a power electronics interface due to the high-power processing requirement. Although connecting UCs directly to the DC bus, without using a power converter, presents considerable advantages, the main disadvantage is related to the UC energy-usage capability, which is limited by constant DC bus control. This paper proposes a novel energy-management strategy based on a fuzzy inference system, for fuel-cell/battery/ultracapacitor hybrid electric vehicles. The proposed strategy is able to control the charge and discharge of the UC bank in order to take advantage of its energy storage capability. Experimental results show that the proposed strategy reduces the waste of energy due to dynamic brake in 14%. This represents a reduction in energy consumption from 218 Wh/km to 192 Wh/km for the same driving conditions. By using the proposed energy management strategy, the estimated fuel efficiency in miles per gallon equivalent was also increase from 96 mpge to 109 mpge.

Control Oriented Modelling of a Turboshaft Engine for Hybrid Electric Urban Air-Mobility

The electrification of aircraft is a well-established trend in recent years in order to achieve economic and environmental sustainability. In this framework, an application particularly interesting for hybrid electric power system is represented by urban air-mobility. For this application, the authors presented a parallel hybrid electric power system including a turboshaft engine and two electric motors and proposed a quasi-stationary simulation tool. As a further step, this paper deals with the dynamic modelling of the same turboshaft engine within the framework of a hybrid electric system where the pilot command is interpreted as a power request to be satisfied by the engine and the electric machine according to the selected energy management strategy. In this work, the dynamic behaviour of the turboshaft engine is analysed with and without the help of the electric motors to satisfy the power demand.

Polymer Matrix Nanocomposites with 1D Ceramic Nanofillers for Energy Storage Capacitor Applications.

Recent developments in various technologies, such as hybrid electric vehicles and pulsed power systems, have challenged researchers to discover affordable, compact, and super-functioning electric energy storage devices. Among the existing energy storage devices, polymer nanocomposite film capacitors are a preferred choice due to their high power density, fast charge and discharge speed, high operation voltage, and long service lifetime. In the past several years, they have been extensively researched worldwide, with 0D, 1D, and 2D nanofillers being incorporated into various polymer matrixes. However, 1D nanofillers appeared to be the most effective in producing large dipole moments, which leads to a considerably enhanced dielectric permittivity and energy density of the nanocomposite. As such, this Review focuses on recent advances in polymer matrix nanocomposites using various types of 1D nanofillers, i.e., linear, ferroelectric, paraelectric, and relaxor-ferroelectric for energy storage applications. Correspondingly, the latest developments in the nanocomposite dielectrics with highly oriented, surface-coated, and surface-decorated 1D nanofillers are presented. Special attention has been paid to identifying the underlying mechanisms of maximizing dielectric displacement, increasing dielectric breakdown strength, and enhancing the energy density. This Review also presents some suggestions for future research in low-loss, high energy storage devices.

Implementation of energy management strategy of hybrid power source for electrical vehicle

Managing the energy is one of the most important issues for the efficiency of vehicular applications using hybrid electric power systems. This paper deals with an analysis of an energy management for hybrid power system, which consists of fuel cell, ultra-capacitor and battery and dedicated to electrical vehicles. Thus, an energy management method is applied in order to split the energy flow between the three used sources. This strategy is based on a combination of three control methods; a fuzzy logic control, a flatness control and rule-based algorithm. For the fuzzy logic, the main idea is inspired from rule-based algorithms except that it is more flexible and less aggressive. The second technic is an innovative control using the flatness property for a Fuel cell/ supercapacitor/ Battery hybrid power system. For the rules based algorithm, it uses a supercapacitor state-of-charge control principle. Then, an experimental validation is done for the energy management method to show the efficiency of the proposed control strategy in term of the well share of the energy between sources to satisfy the load demand. A dSpace real-time card is used for management algorithm implementation and data acquisition. The obtained experimental results prove the efficiency and the validity of the proposed supervisor.

Synergy Effects in Electric and Hybrid Electric Aircraft

The interest in electric and hybrid electric power system has been increasing, in recent times, due to the benefits of this technology, such as high power-to-weight ratio, reliability, compactness, quietness, and, above all, elimination of local pollutant emissions. One of the key factors of these technologies is the possibility to exploit the synergy between powertrain, structure, and mission. This investigation addresses this topic by applying multi-objective optimization to two test cases — a fixed-wing, tail-sitter, Vertical Take-off and Landing Unmanned Aerial Vehicle (VTOL-UAV), and a Medium-Altitude Long-Endurance Unmanned Aerial Vehicle (MALE-UAV). Cruise time and payload weight were selected as goals for the first optimization problem, while fuel consumption and electric endurance were selected for the second one. The optimizations were performed with Non-dominated Sorting Genetic Algorithm-II (NSGA-II) and S-Metric Selection Evolutionary Multiobjective Algorithm (SMS-EMOA), by taking several constraints into account. The VTOL-UAV optimization was performed, at different levels (structure only, power system only, structure and power system together). To better underline the synergic effect of electrification, the potential benefit of structural integration and multi-functionalization was also addressed. The optimization of the MALE-UAV was performed at two different levels (power system only, power system, and mission profile together), to explore the synergic effect of hybridization. Results showed that large improvements could be obtained, either in the first test case when, both, the powertrain design and the aircraft structure were considered, and in the optimization of the hybrid electric UAV, where the optimization of the aircraft flight path gave a strong contribution to the overall performances.

On the Optimal Design of Hybrid-Electric Power Systems for Offshore Vessels

Evolution of technology is significantly increasing the presence of hybrid-electric power systems in offshore (support/operation) vessels. They require high dynamic response including dynamic positioning and high levels of reliability and safety. This paper presents a methodology for the optimal design of hybrid-electric power systems for all-electric offshore vessels focused on economic objectives. The methodology is based on the energy modeling of the most promising hybrid-electric power system architectures, as well as the use of an advanced multiobjective optimization technique to obtain the Pareto set of noninferior solutions, corresponding to the best sizing of the energy storage system and energy management strategy. Therefore, modern vessel power systems (ac or dc distribution systems designed around the use of power electronics converters and energy storage systems) can be optimized in terms of fuel consumption, emissions, and capital expenditure/operational expenditure according to the vessel operation modes and power profiles.

Determination Methodology for Stability Domain of Hybrid Electric Power System with Multiple Excitation Sources

Irregular internal excitation (engine excitation and motor excitation) and external load excitation can cause torsional vibration in hybrid electric propulsion system which even leads to the break of shaft. The objective of this paper is to determinate the stability domain of hybrid electric power system under different drive mode with multiple excitation sources. To achieve the goal, the simplified three-mass torsional model of hybrid electric power system is established. Then we apply the multi-scale method to solve the nonlinear torsional model. Finally we set different parameters of engine speed to simulate torsional vibration characteristics of hybrid electric power system. The simulation results exhibit that the torsional vibration characteristics of hybrid electric power system under two drive mode are different because the directional relationship of the moment of engine and permanent magnet synchronous motor (PMSM) is distinctive. It’s hard to eliminate the torsional vibration of hybrid electric propulsion system due to phase difference between the engine excitation and the load excitation.

Recent Coyote Algorithm-Based Energy Management Strategy for Enhancing Fuel Economy of Hybrid FC/Battery/SC System

An optimized energy management strategy (EMS) based on a recent coyote optimization algorithm (COA) applied to a hybrid electric power system is proposed in this paper. The proposed hybrid system comprises fuel cell (FC), battery storage bank (BSB) and supercapacitors (SCs). The FC has been selected to be the chief power source to meet the load demand at steady state. Whereas BSB is used as the chief energy buffer and to help the FC during deficit periods and SCs are employed to meet the transient maximum power. The performance of the hybrid electric power system mostly depends on how to distribute the demanded load through different kinds of power sources. Therefore, optimized EMS is highly required to do this job. The key objective of the proposed EMS is to reduce hydrogen consumption by the hybrid system and increase the durability of power sources. To investigate the superiority and validity of COA, a comparison with other approaches is carried based on minimum hydrogen consumption and high energy efficiency. Such methods include external energy maximization strategy (EEMS), particle swarm optimizer (PSO), genetic algorithm (GA), grey wolf optimizer (GWO), grasshopper optimization algorithm (GOA), multi-verse optimizer (MVO), salp swarm algorithm (SSA) and sunflower optimization (SFO). The obtained results confirmed the superiority of the proposed COA. Using COA reduced hydrogen consumption by 38.8% compared to the EEMS method. Based on the minimum hydrogen consumption, the strategies are ranked from the best as following; COA, GWO, SSA, GOA, MVO, GA, PSO, and EEMS.

An Application of the ECMS Strategy to a Wankel Hybrid Electric UAV

In a previous work, the authors optimized the hybrid electric power system for a tactical Unmanned Aerial Vehicle including a Wankel engine as thermal converter and a permanent magnet electric motor powered by lithium batteries. Startingfrom this optimal configuration, we address here the topic of a refined optimization of the energy management strategy, i.e. the contribution of the battery to the required power in each segment of the flight. The Equivalent Consumption Minimization Strategy (ECMS) was chosen with the goal of minimizing fuel consumption while fully depleting the energy stored in the battery from the beginning to the end of each mission.

TOpti: a flexible framework for optimising energy management for various ship machinery topologies

In the early stages of the ship design process, the system designer must choose which type of machinery system will be used to power the ship. Hybrid power systems, which are familiar in the automotive industry, have started making a breakthrough in the marine industry. However, defining the length of the financial payback period is not trivial for ship designers, which makes it harder to adopt these more expensive technologies. The shortage of on-board machinery integration software for maritime engineers has motivated the authors of this article to develop a tool that can assist ship designers in making the right choices early in the design process. Discovering the optimal power system design for a specified vessel’s operation requires optimal machinery control. This article presents a novel method to optimise the machinery control of a system specified by the tool user. A case study is presented using a fishing boat with both diesel-mechanical and hybrid electric power systems.

Hybridization of training aircraft with real world flight profiles

PurposeThe purpose of this paper is to analyze real-world flight data of a piston engine training aircraft collected from an internet-based radar service, along with wind data provided by a weather forecast model, and to use such data to design a hybrid electric power system.Design/methodology/approachThe modeling strategy starts from the power demand imposed by a real-world wind-corrected flight profile, where speed and altitude are provided as functions of time, and goes through the calculation of the efficiency of the powertrain components when they meet such demand. Each component of the power system and, in particular, the engine and the propeller, is simulated as a black box with an efficiency depending on the actual working conditions. In the case of hybrid electric power system, the battery charging and discharging processes are simulated with the Shepherd model.FindingsThe variability of power demand and fuel consumption for a training aircraft is analyzed by applying the proposed methodology to the Piper PA-28-180 Cherokee, a very popular aircraft used for flight training, air taxi and personal use. The potentiality of hybridization is assessed by analyzing the usage of the engine over more than 90 flights. A tentative sizing of a hybrid electric power system is also proposed. It guarantees a fuel saving of about 5%.Originality/valueThe scientific contribution and the novelty of the investigation are related to the modeling methodology, which takes into account real-world flight conditions, and the application of hybridization to a training aircraft.

Fuel consumption of rotorcrafts and potentiality for hybrid electric power systems

The paper proposes a simulation approach to evaluate the power required by a rotorcraft in standard flight missions and in emergency landing maneuvers, and the corresponding fuel consumption, in order to compare the feasibility and potential fuel savings for different hybrid power systems. More in detail, three options are analyzed, namely electrification of the tail rotor, fully hybrid electric propulsion and electric emergency landing. Weight penalty and potential fuel saving for the proposed hybridization schemes are evaluated for an Agusta-Westland A109 twin engine helicopter model. Nonetheless the discussed methods of analysis have general validity for single main rotor helicopter configurations.Two different scenarios are considered in this investigation: current technologies for batteries and motors and improved electrical components, with performance projections as of 2040. According to this analysis, electrification of the tail rotor and parallel hybridization are feasible with available technology, whereas a fully electrical power system for emergency landing could be developed only in the future. Finally, a parallel hybrid electric power system is sized according to the analysis of power request over four different missions. Fuel savings are evaluated for different energy management strategies. According to the results of this investigation, the parallel hybrid electric power system with present-day and future technologies can save fuel up to 5% and 12%, respectively, with an appropriate energy management strategy.

Frequency Transient Suppression in Hybrid Electric Ship Power Systems: A Model Predictive Control Strategy for Converter Control with Energy Storage

This paper aims to understand how the common phenomenon of fluctuations in propulsion and service load demand contribute to frequency transients in hybrid electric ship power systems. These fluctuations arise mainly due to changes in sea conditions resulting in significant variations in the propulsion load demand of ships. This leads to poor power quality for the power system that can potentially cause hazardous conditions such as blackout on board the ship. Effects of these fluctuations are analysed using a hybrid electric ship power system model and a proposed Model Predictive Control (MPC) strategy to prevent propagation of transients from the propellers into the shipboard power system. A battery energy storage system, which is directly connected to the DC-link of the frequency converter, is used as the smoothing element. Case studies that involve propulsion and service load changes have been carried out to investigate the efficacy of the proposed solution. Simulation results show that the proposed solution with energy storage and MPC is able to contain frequency transients in the shipboard power system within the permissible levels stipulated by the relevant power quality standards. These findings will help ship builders and operators to consider using battery energy storage systems controlled by advanced control techniques such as MPC to improve the power quality on board ships.

Post-Installation: Insight of coastal-area society in Hybrid Electric Power Systems (HEPS) of Pantai Baru, Yogyakarta

The Hybrid Electric Power Systems project is a pilot renewable energy project of the Indonesian Ministry of Research and Technology since 2010. Hybrid power (windmill and solar cell) was chosen because of their huge heat and wind potential in coastal area of Pantai Baru. Post-installation is critical, considering the existence of alternative energy was expected to bring changes in the life of coastal people nearby. Participatory Action Research (PAR) was the method used to do deeper exploration of the changes happened after the hybrid electric power installation in Pantai Baru. Coastal society had a bigger dependency on natural resources and secluded from any technology development, including the hybrid power itself. The use of PAR method reversed the top down logic by the Indonesian Ministry of Research and Technology with the bottom up logic, adjust the people’s needs which processed from the grassroots. This research was conducted in three years, using three approaches; exploration, reflection, and action. Through these approaches, it was possible for the researchers to understand the actual condition of coastal society and chose the women groups as the main informants as well as the main group which got the biggest benefits of the Hybrid Electric Power Systems (HEPS), they were capable of giving fast responses on the changes happened through the culinary, tourism, fishpond, etc. This condition emphasized both the central role of women and the knot of all dynamics of the HEPS installation. In conclusion, women groups positioned themselves as the transformation agent of the usage of this renewable energy around HEPS Pantai Baru. As the main beneficiaries, women groups had improved their capability to adapt. It increased the income, consumption level, etc. Despite the success of the adaptation, they were still failing their position as the agents and users of the renewable energy. Their existence was limited merely to objects/beneficiaries, instead of being the subjects/actors of the HEPS technology. This study is essential as a data baseline, prepare the policy of technology intervention as well renewable energy campaign.

Experimental investigation into the fault response of superconducting hybrid electric propulsion electrical power system to a DC rail to rail fault

Hybrid electric propulsion aircraft are proposed to improve overall aircraft efficiency, enabling future rising demands for air travel to be met. The development of appropriate electrical power systems to provide thrust for the aircraft is a significant challenge due to the much higher required power generation capacity levels and complexity of the aero-electrical power systems (AEPS). The efficiency and weight of the AEPS is critical to ensure that the benefits of hybrid propulsion are not mitigated by the electrical power train. Hence it is proposed that for larger aircraft (~200 passengers) superconducting power systems are used to meet target power densities. Central to the design of the hybrid propulsion AEPS is a robust and reliable electrical protection and fault management system. It is known from previous studies that the choice of protection system may have a significant impact on the overall efficiency of the AEPS. Hence an informed design process which considers the key trades between choice of cable and protection requirements is needed. To date the fault response of a voltage source converter interfaced DC link rail to rail fault in a superconducting power system has only been investigated using simulation models validated by theoretical values from the literature. This paper will present the experimentally obtained fault response for a variety of different types of superconducting tape for a rail to rail DC fault. The paper will then use these as a platform to identify key trades between protection requirements and cable design, providing guidelines to enable future informed decisions to optimise hybrid propulsion electrical power system and protection design.

Ground simulation of a hybrid power strategy using fuel cells and solar cells for high-endurance unmanned aerial vehicles

A hybrid electric power system for high-endurance unmanned aerial vehicles is tested on the ground, alternating between fuel and solar cell power. A fuel cell system is constructed using a micro-processed controller, micro-pump, hydrogen generator using 20 wt% liquid sodium borohydride (NaBH4) solution, and proton exchange membrane fuel cell stack connected with a battery in parallel. The solar cell system consisted of a DC-DC converter, a battery, and solar modules. These two power sources are integrated via a power switching strategy using two solid-state relays connected to the controller, which turn on the fuel cell system to provide the power necessary to satisfy the load while the solar power system is on standby, charging the solar cell battery, or vice versa. In this way, not only is the operational period increased with high reliability by making one power source be on standby while the other is in use, but also the control logic of the system is simplified. Moreover, the fuel cell power could be adjusted by flowing different amounts of NaBH4 solutions using a controller to save liquid fuel, thereby extending the operational time.

Techno-economic analysis of a hybrid system to power a mine in an off-grid area in Ghana

In spite of the abundance of renewable energy and its potential application to mining industries, Ghana has not seen much investment in this area. The provision of electricity for mining activities in Ghana is cost intensive, especially in remote areas that are not connected to utility-grids. In this study, a technical and economic analysis of a hybrid electric power system for an off-grid mine company was conducted. Three different hybrid systems, together with a “Generator only” system as base case were analysed using HOMER software, to select the optimum energy system. The selected system consists of 50MW of Solar PV, 15MW of fuel cell system, 600 batteries, 20.5MW of converter and 20MW of diesel generator. The system produces 152.99GWh of electric energy annually. The PV array produces 44%, the fuel cell produces 40% and the diesel produces 14%. At the current cost of system components, and based on assumptions adopted in this study, the optimal system yields a cost of energy of US$0.25/kW and a least cost of energy of US$0.22/kWh, at a diesel price of US$0.80/litre and 30% reduction in both PV module and fuel cell system costs.

Design and performance evaluation of a hybrid electric power system for multicopters

The aim of the proposed investigation is to design and analyze the performance of a hybrid electric power system for multicopter and to evaluate its performance. To this, the overall power request was assumed to be satisfied in three possible ways: a battery (electric power system), a generator powered by a two-stroke internal combustion engine (thermal power system), and both battery and engine (hybrid power system). The fuel stored on board was calculated for each configuration by keeping constant the overall mass. In the hybrid case, the engine also allows the battery to be recharged during the flight with an on/off behavior of the engine. Electric mode is started when the batteries are sufficiently charged and can produce the required propulsive power. This mode goes on as long as the state of charge (SOC) is above a minimum value. When the SOC is lower than this value, the batteries let the engine be restarted by the generator. Then, the engine generates both the power for propulsion and to recharge the battery. After a sensitivity analysis, an optimization has been performed by considering different thresholds for the battery state of charge to shift from electric to recharge mode and by taking into account different values of the recharge current. The methodology was applied to two different multicopters and the proposed powertrains were simulated with a backward approach starting from experimental time histories of required electric power.

Design of a Hybrid PV/Wind/Diesel Generator Energy System for 120 Residential Apartments in Gusau

Gusau, a city in zamfara state, Nigeria is faced with the challenge of inadequate power supply as electricity supply from the national grid is unstable and inadequate, besides majority of those in the remote areas are isolated from the grid. The location has a potential for renewable resources, to overcome this challenge of inadequate power supply, a hybrid electric power system which employs the use of battery storage, solar and wind energy system with a diesel generator as reserve to provide adequate power to 120 residential apartments in a settlement isolated from the grid is being designed. The solar and wind energy resources in the location were assessed; the data from the two renewable energy resources available in the location was collected for the year 2015 from the Nigerian meteorological Agency, NIMET alongside the geographical coordinates and other useful parameters as input to the HOMER software simulator for analysis. The load profile of the location was carried out, the sizing of the energy mix from PV, wind, battery and generator was made using the software. The result of the simulation shows a yearly electricity production of 168,545KWh/yr, the yearly AC primary load is 67160KWh/yr. And the excess electricity is 88581Kwh/yr, this accounts for 52.6% of the total electricity generated hence, the hybrid energy system has the potential to provide the micro-grid with adequate power with high penetration of renewable energy.

Energy Optimal Control Strategy of PHEV Based on PMP Algorithm

Under the global voice of “energy saving” and the current boom in the development of energy storage technology at home and abroad, energy optimal control of the whole hybrid electric vehicle power system, as one of the core technologies of electric vehicles, is bound to become a hot target of “clean energy” vehicle development and research. This paper considers the constraints to the performance of energy storage system in Parallel Hybrid Electric Vehicle (PHEV), from which lithium-ion battery frequently charges/discharges, PHEV largely consumes energy of fuel, and their are difficulty in energy recovery and other issues in a single cycle; the research uses lithium-ion battery combined with super-capacitor (SC), which is hybrid energy storage system (Li-SC HESS), working together with internal combustion engine (ICE) to drive PHEV. Combined with PSO-PI controller and Li-SC HESS internal power limited management approach, the research proposes the PHEV energy optimal control strategy. It is based on revised Pontryagin’s minimum principle (PMP) algorithm, which establishes the PHEV vehicle simulation model through ADVISOR software and verifies the effectiveness and feasibility. Finally, the results show that the energy optimization control strategy can improve the instantaneity of tracking PHEV minimum fuel consumption track, implement energy saving, and prolong the life of lithium-ion batteries and thereby can improve hybrid energy storage system performance.