scholarly journals Coordinated Control of Diesel Generators and Batteries in DC Hybrid Electric Shipboard Power System

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6246
Author(s):  
Luona Xu ◽  
Baoze Wei ◽  
Yun Yu ◽  
Josep M. Guerrero ◽  
Juan Vasquez
Keyword(s):  
Operation Mode ◽  
Power Sharing ◽  
Mode Switching ◽  
Maritime Industry ◽  
Power Sources ◽  
Operation Modes ◽  
Dc Bus ◽  
Hybrid Electric ◽  
Diesel Generators ◽  
Bus Voltage

Hybrid electric ships powered by diesel generators and batteries are the main configuration for shipboard microgrids (SMGs) in the current maritime industry. Extensive studies have been conducted for the hybrid operation mode, whereas the all-electric operation mode and the switching between the aforementioned two modes in a system with multiple generators and batteries have not been tested. In this paper, a coordinated approach for a hybrid electric ship is proposed, where two operation modes have been simultaneously considered. More specifically, for achieving an efficient operation with reduced generator wear losses, the governor-less diesel-engine-driven generators have been adopted in the study. According to the practical operation conditions, two operation modes, the all-electric and hybrid modes, are preset. Based on these, the coordination of the generators acting as the main power sources and batteries regulating the power flow and improving the generator efficiency is studied. The governor-less diesel generators are regulated to inject the rated power in order to maximize the generator efficiency, while the DC bus voltage is regulated by DC/DC converters. For the benefit of the overall lifespan of battery banks, power sharing during charging and discharging states have been realized by the state of charge (SoC)-based adaptive droop regulator. For the test of two operation modes, as well as the mode switching, a simulation assessment in a 1 kV DC SMG has been conducted. The simulation results show that the DC bus voltage can be controlled well, and that the power sharing among batteries follows the design. Additionally, smooth transients can be observed during mode switching when the proposed control scheme is applied.

scholarly journals Design and Implementation of an Energy-Management System for a Grid-Connected Residential DC Microgrid

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4074
Author(s):  
Alfredo Padilla-Medina ◽  
Francisco Perez-Pinal ◽  
Alonso Jimenez-Garibay ◽  
Antonio Vazquez-Lopez ◽  
Juan Martinez-Nolasco
Keyword(s):  
Energy Management ◽  
Management System ◽  
Operation Mode ◽  
Maximum Energy ◽  
Energy Management System ◽  
Dc Microgrid ◽  
Design And Implementation ◽  
Operation Modes ◽  
Dc Bus ◽  
Bus Voltage

The design and implementation of an energy-management system (EMS) applied to a residential direct current microgrid (DC-µG) is presented in this work. The proposed residential DC-µG is designed to provide a maximum power of one kilowatt by using two photovoltaic arrays (PAs) of 500 W, a battery bank (BB) of 120 V–115 Ah, a supercapacitor module of 0.230 F and a bidirectional DC–AC converter linked to the AC main grid (MG). The EMS works as a centralized manager and it defines the working operation mode for each section of the DC-µG. The operation modes are based on: (1) the DC-link bus voltage, (2) the generated or demanded power to each section of the DC-µG and (3) the BB’s state of charge. The proposed EMS—during the several working operation modes and at the same time—can obtain the maximum energy from the PAs, reduce the energy consumption from the main grid and keep the DC-link bus voltage inside a range of 190 V ± 5%. The EMS and local controllers are implemented by using LabVIEW and NI myRIO-1900 platforms. Moreover, experimental results during connection and disconnection of each DC-µG sections and different on-the-fly transitions are reported, these results focus on the behavior of the DC bus, which shows the DC bus robustness and stability. The robustness of the DC-µG is demonstrated by maintaining a balance of energy between the sources and loads connected to the DC bus under different scenarios.

scholarly journals Control Strategy of Mode Transition with Engine Start in a Plug-in Hybrid Electric Bus

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2989 ◽  
Author(s):  
Yang ◽  
Zhang ◽  
Zhang ◽  
Tian ◽  
Hu
Keyword(s):  
Control Strategy ◽  
Transition Process ◽  
Structural Features ◽  
Driving Performance ◽  
The State ◽  
Switching Process ◽  
Mode Switching ◽  
Mode Transition ◽  
Power Sources ◽  
Hybrid Electric

Torque coordinated control of the relevant power sources has an important impact on the vehicle dynamics and driving performance during the mode transition of the hybrid electric vehicles(HEVs). Considering the dynamic impact problem caused by mode transition, this paper, based upon the structural features of axially paralleled hybrid power system, introduces the bumpless mode switching control theory to analyze multi-mode transition. Firstly, the state transition process is abstracted as the state space transition problem of hybrid system. Secondly the mode transition is divided into four sub-states, and the state model of each sub-state is established. Thirdly, taking the cost functions as the optimization objective, the state switching process is solved, and the control vectors of each switching process are obtained. Simulation and experimental results show that the proposed control strategy can effectively suppress torque fluctuation, avoid longitudinal acceleration impact, and improve driving performance.

scholarly journals Improved Dynamic Voltage Regulation in a Droop Controlled DC Nanogrid Employing Independently Controlled Battery and Supercapacitor Units

2018 ◽  
Vol 8 (9) ◽  
pp. 1525
Author(s):  
Ahmad M. A. Malkawi ◽  
Luiz A. C. Lopes
Keyword(s):  
Energy Storage ◽  
Storage System ◽  
Voltage Regulation ◽  
Potential Contribution ◽  
Pass Filter ◽  
Power Sources ◽  
Dynamic Voltage ◽  
Dc Bus ◽  
Bus Voltage ◽  
The Impact

DC bus voltage signaling (DBS) and droop control are frequently employed in DC nano and microgrids with distributed energy resources (DERs) operating in a decentralized way. This approach is effective in enforcing the desired contributions of power sources and energy storage systems (ESSs) in steady-state conditions. The use of supercapacitors (SCs) along with batteries in a hybrid energy storage system (HESS) can mitigate the impact of high and fast current variations on the losses and lifetime of the battery units. However, by controlling the HESS as a single unit, one forfeits the potential contribution of the SC and its high power capabilities to dynamically improve voltage regulation in a DC nanogrid. This paper discusses an approach where the SC interface is controlled independently from the battery interface, with a small droop factor and a high pass filter (HPF), to produce high and short current pulses and smooth DC bus voltage variations due to sudden power imbalances in the DC nanogrid. Experimental results are presented to show that, unlike in a conventional HESS, the SC unit can be used to improve the dynamic voltage regulation of the DC nanogrid and, indirectly, mitigate the high and fast current variations in the battery.

scholarly journals A hybrid power system based on fuel cell, photovoltaic source and supercapacitor

2020 ◽  
Vol 2 (5) ◽  
Author(s):  
Seydali Ferahtia ◽  
Ali Djerioui ◽  
Samir Zeghlache ◽  
Azeddine Houari
Keyword(s):  
Fuel Cell ◽  
Power Sharing ◽  
Dc Microgrid ◽  
Storage Element ◽  
Load Variations ◽  
Management Algorithm ◽  
Controversial Topic ◽  
Management Method ◽  
Dc Bus ◽  
Bus Voltage

Abstract In this study, we present an ameliorated power management method for dc microgrid. The importance of exploiting renewable energy has long been a controversial topic, and due to the advantages of DC over the AC type, a typical DC islanded micro-grid has been proposed in this paper. This typical microgrid is composed of two sources: fuel cell (FC), solar cell (PV) and one storage element [supercapacitor (SC)]. Here, we aimed to provide a management strategy that guarantees optimized bus voltage with arranged power-sharing between the sources. This proposed management aims to provide high-quality energy to the load under different loading conditions with variable solar irradiance, taking into account the FC state. Due to the slow dynamics of the FC, the SC was equipped to supply the transient period. A management algorithm is implemented to hold the DC bus voltage stable against the load variations. The management controller is based on differential flatness approach to generate the references. The DC bus is regulated by the SC energy; to reduce the fluctuations in the DC bus voltage, The PI controller is implemented. This proposed strategy reduces the voltage ripple in the DC bus. Moreover, it provides permanent supplying to the load with smooth behaviour over the sudden changes in the demand as depicted in the simulation results. Our study revealed that this proposed manager can be used for this kind of grids easily.

scholarly journals Effects of Reversed Shock Waves on Operation Mode in H2/O2 Rotating Detonation Chambers

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8296
Author(s):  
Yanliang Chen ◽  
Xiangyang Liu ◽  
Jianping Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Operation Mode ◽  
Wave Number ◽  
Mode Switching ◽  
Rotating Waves ◽  
Operation Modes ◽  
Rotating Detonation

Operation modes are an important topic in the research of Rotating Detonation Chamber (RDC) as it can affect the stability of RDC. However, they have not been discussed in detail due to the limitation of measurement means in experiments. The aim of this research is to investigate the mechanism of different operation modes by numerical simulation. In this paper, a numerical simulation for RDCs with separate injectors is carried out. Different operation modes and mode switching are analyzed. There is a series of reversed shock waves in the flow field. It was found that they have great effects on operation mode and mode switching in RDCs. A reversed shock wave can transit into a detonation wave after passing through isolated fresh gas region where fresh gas and burnt gas distribute alternatively. This shock-to-detonation transition (SDT) phenomenon will influence the ignition process, contra-rotating waves mode and mode switching in RDCs. SDT makes the number of detonation wave increases, resulting in multi-wave mode with one ignition. Moreover, quenching of detonation waves after collision and SDT after passing through isolated fresh gas region are the mechanism of contra-rotating waves mode in RDCs with separate injectors. In addition, when the inlet total temperature increases, a shock wave is easier to transit into a detonation wave. The distance that a shock wave travels before SDT decreases when temperature increases. This will result in mode switching. Therefore, SDT determines that there is a lower bound of detonation wave number.

scholarly journals Research on a Plug-In Hybrid Electric Bus Energy Management Strategy Considering Drivability

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2177 ◽  
Author(s):  
Ye Yang ◽  
Youtong Zhang ◽  
Jingyi Tian ◽  
Si Zhang
Keyword(s):  
Real Time ◽  
Energy Management ◽  
Management Strategy ◽  
High Efficiency ◽  
Ride Comfort ◽  
Mode Switching ◽  
Energy Management Strategy ◽  
Power Sources ◽  
Optimal Energy ◽  
Hybrid Electric

Plug-in hybrid electric buses (PHEBs) is some of the most promising products to address air pollution and the energy crisis. Considering the switching between different working modes often bring aboutsudden changes of the torque and the speed of different power sources, which may lead to the instability of the power output and affect the driving performance and ride comfort, it is of great significance to develop a real-time optimal energy management strategy for PHEBs to achieve the optimization of fuel economy and drivability. In this study, the proposed strategy includes an offline part and an online part. In the offline part, firstly, the energy conversion coefficient s(t) is optimized by linear weight particle swarm optimization algorithm (LinWPSO), then, the optimization results of s(t) are converted into a 2-dimensional look-up table. Secondly, combined with three typical driving cycle conditions, the gear-shifting correction and mode switching boundary parameters that affect the drivabilityof the vehicle are extracted by dynamic programming (DP) algorithm. In the online part, combined with the s(t), the gear-shifting correction and mode switching boundary parameters which are obtained through offline optimization, the real-time energy management strategy is proposed to solve the trade-off problem between minimizing the fuel consumption and improving the drivability and riding comfort. Finally, the proposed strategy is verified with simulation, the results show that the proposed strategy can guarantee the engine and the electric motor (EM) work in the high-efficiency area with optimal energy distribution while keeping drivability in the variation of driving circle. The overall performance is improved by 18.54% compared with the rule-based control strategy. The proposed strategy may provide theoretical support for the optimal control of PHEB.

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