Parallel connected distributed generation with energy storage systems (ESSs) are popular in modern sustainable microgrids. Absence of proper coordination between ESSs can lead to reduced system lifespan due to unnecessary deep discharge or premature fully charged of individual battery. This paper proposes an energy management strategy aimed at elimination of this problem by balancing the state-of-charge (SoC) of parallel connected ESSs in DC microgrids using voltage droop control which is a function of SoC and current. This was examined by simulation which shows that the proposed strategy was simple and effective under both islanded mode and grid connected situations.
In this paper, the model of the electric vehicles (EVs) with the hybrid energy storage system (HESS) consisting of battery and super-capacitor is proposed. Using the proposed model, the operation of the EV with HESS is simulated for various energy distributions of battery and super-capacitor (SC) energy storage system. The losses of the battery and super-capacitor, the travelled distance and the ratio of the SC power to the bus power are investigated and discussed. The study in this paper reveals the relationships between the losses of the battery and the super-capacitor, the energy distribution, the power allocation, the travelled distance and the load, and shows that the optimal ratio of the SC power to the bus power can be found to minimize the losses of the battery and the SC and maximize the travelled distance of the EV. Thus, this paper offers the valuable investigation for the optimal energy management and the maximum efficiency control of HESS.
In the view of the outstanding advantage, high frequency AC (HFAC) power distribution system (PDS) has already an extensive application from telecommunication system to electric vehicle. Resonant inverter as the high frequency power source provides fixed frequency output for point of load (POL). The controller designed with ever increasing frequency becomes more complicated, because the robustness and dynamic performance will deteriorate so as to greatly affect the stability of resonant converters. A sliding mode controller of phase angle is proposed for full-bridge series-parallel resonant inverter with unified phase-shift-modulation (PSM). The proposed nonlinear controller can effectively cooperate with the conventional controller of output magnitude to improve system robustness and dynamic performance. Furthermore, a simulation prototype is implemented for performance evaluation with a rated output power of 120W and operation frequency of 25 kHz.
India, being a tropical country has rich solar resource. Hence, with a strong commitment towards increasing its renewable share, India has set a target to install 100 GW of solar generation capacity by 2022 in which 40 GW would be grid-connected rooftop solar photovoltaic (PV) systems. This paper examines the potential, importance, foreseen challenges, outlook, and technical impact due to large-scale deployment of grid-connected rooftop solar PV systems in India.
Concerning the realistic situation of power system in China, a novel unit commitment method is presented which takes comprehensive consideration for the coordinative operation of wind energy, demand response and thermal power. The proposed day-ahead scheduling scheme is aimed at practical utilization in current grid foundation. Particularly, this paper takes a practical consideration for the actual electricity consumption of electrical vehicles in China on the side of clients. A price mechanism based on power consumption contract of electrical vehicles (EVs) is proposed so that customers could regulate their charging behaviors towards an EV-friendly type. Moreover, a ten-level set of demand response is used and the uncertainty of wind power generation is regulated by a polyhedron set. The optimization model is built on an IEEE 114-bus system with 5 units, which is then solved by a real-code genetic algorithm. As shown in the numerical study, the proposed model can provide specific and economic beneficial dispatching schemes for system operators as well regulate power consumption of EVs, which effectiveness has been verified.
Energy storage is getting more important because of the demand in energy usage for green application. Electric vehicle, hybrid electric vehicle and electric vessel are rapidly emerged and represent new mobility to be developed for this century. To enable such development, good energy storage devices besides battery and super-capacitor are needed seriously. New battery management system, balancing skill and switched-capacitor techniques are examined for applications in this paper. DC power conversion has great benefit and will be an alternative design for smart city to give direct power. Even the electric vehicle will be based on all electric direct drive to eliminate the mechanical subsystem including transmission and bulky suspension. IN this paper, different types of power conversion are described for future mobility and smart city.
In this paper, the main conductive and radiative electromagnetic sources are introduced especially for low frequency electromagnetic sources. Systematic and equipment view of electromagnetic field in the normal operation are simulated and analyzed by Maxwell and HFSS based on FEM. This paper provides an overview of the low frequency conductive and radiative EMI and EMC for the high speed railway.
Lithium-titanate battery is a kind of new lithium-ion batteries, and it can be charged by high current, but changes in temperature and capacity have a great influence on the battery performance. The battery stability and the charging curve are examined in this paper for the high current and various test conditions. It is found that the LTO has an advanced performance in temperature rise.
The paper presents the investigation of the electromagnetic interference for the traction system in a high speed railway (HSR). Tt is important to study the characteristic of the transformer, converter and power cable for HSR. Traction transformer as the one of the first equipment on board traction system for connection to pantograph, and plays a key role in the electromagnetic investigation. In this paper, the characteristic of the transformer is studied to further provide information for investigation of electromagnetic interference.
This paper analyzes a compensating control strategy for stable energy output of the novel direct drive wave energy generator. We propose a compensating control structure based on the unstable second-order linear dynamics for the direct drive wave energy generator, and the dynamics are derived by the on-line system identification method. In the control strategy, we design a servo compensator located at the forward path, in order to cancel the periodical disturbance effect from sea wave energy actuation, serving as a mechanical power source as well. The stability compensator is combined with the local feedback to ensure the generator to track the desired static constant commend precisely. Finally, we highlight the effectiveness of the control strategy through the simulation of the direct drive wave energy generator, and analyze the performance of the proposed control scheme.
In this paper, an inductive wireless charging lane for electric vehicles is presented. The lane proposed here consists of multiple spiral coils, which are laid down on a track. The specific parameters for the layout of the proposed lane are determined through simulation by the finite element analysis (FEA) software Maxwell. A small prototype of the wireless charging lane is constructed and experimental results show that, a modified, scaled-down model vehicle, with receiver coils attached to the bottom, can move smoothly along the lane without any external power excitation.
All-electric intelligent anti-lock braking system (ABS) is a new technology to be developed and applied in the Electric Vehicles(EVs). It could completely replace the traditional mechanical brake as well as hybrid ABS system which is not suitable for electric vehicles. Thus it greatly improves the reaction speed, shorten the braking time, and is more easily to be integrated in the electric vehicle central control unit. It improves the braking performance by optimizing the coefficient of tire adhesion to the ground to in order obtain Maximum braking force. This paper examines an integrated controller of the ABS using Simulink/Stateflow module of Matlab, which consists of a traditional continuous PID and logic limits controller based on finite state machine theory. The two controllers regulate slip ratio and deceleration simultaneously, which can effectively optimize the braking characteristics and further improve the safety of ABS. The ABS parameters including Vehicle velocity, wheel rotational speed, braking displacement, pressure state and slip ratio are investigated to reveal the performance of ABS. This method is simple and suitable for all electric ABS. More importantly, it could solve braking problem under complex road condition and a sudden change of road condition. Quarter-car system is studied for the concept such that the proposed controller can effectively shorten braking distance and duration and also enhance the stability of ABS and has potential to applied to all electric vehicle
In this paper, a direct-drive spherical motor to produce two-degree of freedom rotations has been proposed. The structure and prototype of the motor are given and the basic principles are described, including the operation principle and mathematic theories, etc. Importantly, the two air gaps between the mover and the rotor, the mover and the stator that mainly determine the performance of the motor are analyzed through the magnetic circuit method. Finite element analysis (FEA) is used to calculate some parameters of the motor and torque outputs from the two dimensions as well. The simulation results illuminate the effectiveness and feasibility of the motor proposed.
This paper investigates a long-stroke linear switched reluctance machine (LSRM) with a primary and a secondary translator for industrial conveyance applications. The secondary one can translate according the primary one so that linear compound motions can be achieved. Experimental results demonstrate that the machine is able to realize a composite linear motion from the secondary translator to ground. The steady-state error values can be controlled within ±0.175 mm.
Since the wave energy power generation has a low voltage output and poor stability in low speed, the scheme of a compensation power generation scheme of two bilateral asymmetric linear switched reluctance generators (BALSRG) is proposed. The mathematic model of the BALSRG is derived and machine characteristics are investigated. Two control methods are discussed and compared. Experiment results demonstrate that the voltage capacity and control accuracy can be improved.
As fatigue damage being the most important reason and basis of wind turbine maintenance, a novel active power dispatching approach was proposed to optimize the fatigue distribution of wind turbines in large-scale wind farms. In this approach, the relationship of fatigue and active power of a wind turbine was built. The grid demanded active power of a wind farm was dispatched to wind turbines according to the inverse proportion of fatigue of wind turbines. Especially, available power and lower limit power of a wind turbine were considered well over, so as to the reference active power of a wind turbine could be carried out. The results of simulation illustrate that the proposed solution is a feasible way to optimize fatigue distribution in wind farms and trace the grid demanded output of wind farms, which may contribute to lower visit of maintenance in a wind farm thus cutting down the maintenance cost of large-scale wind farms.
Current passing through conductor in free space of air generates magnetic field which could interfere with the other apparatus nearby or even interrupt it. Inversely, the electromagnetic sources could also be affected by reaction filed or field generated from else. Therefore, the equipment needs to be designed to both blocking and tolerating the electromagnetic radiation. The electromagnetic interference could be mitigated or minimized by many techniques like filtering, earthing, or shielding. Especially in high speed railway, enclosing dc and ac system, high power and lower power system into a limited area requires the equipment generates less electromagnetic Interference (EMI) and could perform against the interference by the other apparatus. Metal box shielding is a method when the circuit design alone cannot satisfy the requirement that the equipment could stand against the environmental EMI or emanating from the equipment. This paper presents a polymer bonded gridded box shielding method which is light, flexible, material saved and suitable for high and low frequency shielding by employing polymer material.
In recent editions of operations management textbooks, sections have been added on topics related to sustainable design. Many of the textbook discussions illustrate design for environment, remanufacturing, and recycling with examples from the electronics industry. Building on this positive trend, this paper points out how educators can further enhance student learning by expanding existing exercises and discussions with additional resources. The paper concludes with a call to integrate sustainable design concepts into operations management and other non-environmental engineering fields that impact product design.
