scholarly journals Improving the Energy Conversion Efficiency for Hydrokinetic Turbines Using MPPT Controller

2020 ◽  
Vol 10 (21) ◽  
pp. 7560
Author(s):  
Rareș-Andrei Chihaia ◽  
Ionuț Vasile ◽  
Gabriela Cîrciumaru ◽  
Sergiu Nicolaie ◽  
Emil Tudor ◽  
...  
Keyword(s):  
Control System ◽  
Energy Conversion Efficiency ◽  
Buck Converter ◽  
Operating Conditions ◽  
Maximum Point ◽  
Electric Generator ◽  
Point Tracking ◽  
Hydrokinetic Turbine ◽  
The Individual ◽  
Power Curves

The research presented in this paper involves the design of a power control system for a hydrokinetic turbine previously tested in real operating conditions. A maximum power point tracking (MPPT) algorithm was designed and simulated using the required parameters for a specific electric generator. The proposed system consists of a generator connected to the hydrokinetic turbine, a three-phase uncontrolled rectifier, a direct current (DC) boost converter with MPPT control to extract maximum available power, and a buck converter to control the amount of power delivered to the load. In order to test the MPPT algorithm, we built the individual blocks on the basis of the corresponding equations of each component. The algorithm considered the specific parameters of the previously tested turbine as input data and simulated the same water velocities for which the turbine had been tested. Thus, the simulation predicted a power output of 105 W for a water velocity of 1.33 m/s, 60 W for 1 m/s, and 30 W for 0.83 m/s. The efficiency of the control system was demonstrated when the instantaneous power value was maintained at a maximum point, regardless of the rotational speed according to the experimental power curves of the driving rotor obtained for certain water velocities.

Numerical Analysis of Centrifugal Pumps Running in Turbine Mode Under Dynamic Operating Conditions

2017 ◽  
Author(s):  
Vincenzo De Rose ◽  
Francesca Martelli ◽  
Massimo Milani ◽  
Luca Montorsi
Keyword(s):  
Cfd Simulation ◽  
Energy Conversion Efficiency ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Pump Operation ◽  
Electric Generator ◽  
Reverse Mode ◽  
Hydropower Plants ◽  
Dynamic Operating ◽  
Turbine Mode

The use of pumps as turbines (PAT) has gained importance in the recent years as a possible alternative to specifically developed turbine for mini/micro hydropower plants. The use of production pump for hydropower generation reduces the capital cost of the plant but the energy conversion efficiency can be remarkably lower. The paper analyses the performance of a production centrifugal pump running both in direct and reverse mode. The analysis calculates theoretically the behavior of the PAT under the best efficiency point and extends the investigation to other operating points using both a combined theoretical approach and CFD simulation under dynamic conditions. The effects of possible modifications to the initial design of the pump are investigated when running in turbine mode and their influence on the standard pump operation is also determined. Numerical simulation demonstrates that the impeller trimming leads to improvement in the PAT efficiency in some operating conditions. Conversely, the rotational speeds close to the values typical for the electric generator reduce the PAT performance. Finally, the modification of the impeller geometry at the turbine inlet increases the PAT efficiency but lowers the performance of the machine when running in pump mode.

Comparison between Seven MPPT Techniques Implemented in a Buck Converter

2019 ◽  
Vol 12 (6) ◽  
pp. 476-486
Author(s):  
Lahcen El Mentaly ◽  
Abdellah Amghar ◽  
Hassan Sahsah
Keyword(s):  
Value Added ◽  
Buck Converter ◽  
Maximum Power ◽  
Solar Irradiation ◽  
Solar Panels ◽  
Maximum Power Point ◽  
Point Tracking ◽  
Pv Panel ◽  
Low Efficiency ◽  
Power Point

Background: The solar field on our planet is inexhaustible, which favors the use of photovoltaic electricity which generates no nuisance: no greenhouse gases, no waste. Methods: It is a high value-added energy that is produced directly at the place of consumption through photovoltaic (PV) solar panels. Notwithstanding these advantages, the maximum power depends strongly on solar irradiation and temperature, which means that a Maximum Power Point Tracking (MPPT) controller must be inserted between the PV panel and the load in order to follow the Maximum Power Point (MPP) continuously and in real time. In this work, MPP’s behavior was simulated at different temperatures and solar irradiations using seven techniques which identify the MPP by different methods. Results: The novelty of this work is that the seven MPPT methods were compared according to a very selective criterion which is the MPPT efficiency as well as a purely digital duty cycle control without using the PI controller. The simulation under the PSIM software shows that the FLC, TP, FSCC, TG, HC and IC methods have almost the same efficiency of 99%, whereas the FOCV method had a low efficiency of 96%. Conclusion: This makes it possible to conclude that the best methods are FLC, HC and IC because they use fewer sensors compared to the rest.

scholarly journals Crystal growth of clathrate hydrate formed with H2 + CO2 mixed gas and tetrahydropyran

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Meku Maruyama ◽  
Riku Matsuura ◽  
Ryo Ohmura
Keyword(s):  
Crystal Growth ◽  
Synthesis Gas ◽  
Water System ◽  
Hydrate Formation ◽  
Growth Dynamics ◽  
Operating Conditions ◽  
Mixed Gas ◽  
Thermodynamic Conditions ◽  
The Individual ◽  
And Storage

AbstractHydrate-based gas separation technology is applicable to the CO2 capture and storage from synthesis gas mixture generated through gasification of fuel sources including biomass. This paper reports visual observations of crystal growth dynamics and crystal morphology of hydrate formed in the H2 + CO2 + tetrahydropyran (THP) + water system with a target for developing the hydrate-based CO2 separation process design. Experiments were conducted at a temperature range of 279.5–284.9 K under the pressure of 4.9–5.3 MPa. To simulate the synthesis gas, gas composition in the gas phase was maintained around H2:CO2 = 0.6:0.4 in mole fraction. Hydrate crystals were formed and extended along the THP/water interface. After the complete coverage of the interface to shape a polycrystalline shell, hydrate crystals continued to grow further into the bulk of liquid water. The individual crystals were identified as hexagonal, tetragonal and other polygonal-shaped formations. The crystal growth rate and the crystal size varied depending on thermodynamic conditions. Implications from the obtained results for the arrangement of operating conditions at the hydrate formation-, transportation-, and dissociation processes are discussed.

scholarly journals Micromagnetic Characterization of Operation-Induced Damage in Charpy Specimens of RPV Steels

2021 ◽  
Vol 11 (7) ◽  
pp. 2917
Author(s):  
Madalina Rabung ◽  
Melanie Kopp ◽  
Antal Gasparics ◽  
Gábor Vértesy ◽  
Ildikó Szenthe ◽  
...  
Keyword(s):  
Neutron Irradiation ◽  
Pressure Vessel ◽  
Operating Conditions ◽  
Magnetic Characteristics ◽  
Pressure Vessel Steel ◽  
Training Procedure ◽  
Vessel Steel ◽  
Before And After ◽  
The Individual ◽  
Magnetic Adaptive Testing

The embrittlement of two types of nuclear pressure vessel steel, 15Kh2NMFA and A508 Cl.2, was studied using two different methods of magnetic nondestructive testing: micromagnetic multiparameter microstructure and stress analysis (3MA-X8) and magnetic adaptive testing (MAT). The microstructure and mechanical properties of reactor pressure vessel (RPV) materials are modified due to neutron irradiation; this material degradation can be characterized using magnetic methods. For the first time, the progressive change in material properties due to neutron irradiation was investigated on the same specimens, before and after neutron irradiation. A correlation was found between magnetic characteristics and neutron-irradiation-induced damage, regardless of the type of material or the applied measurement technique. The results of the individual micromagnetic measurements proved their suitability for characterizing the degradation of RPV steel caused by simulated operating conditions. A calibration/training procedure was applied on the merged outcome of both testing methods, producing excellent results in predicting transition temperature, yield strength, and mechanical hardness for both materials.

scholarly journals A Unified Control Strategy of Distributed Generation for Grid-Connected and Islanded Operation Conditions Using an Artificial Neural Network

2021 ◽  
Vol 13 (11) ◽  
pp. 6388
Author(s):  
Karim M. El-Sharawy ◽  
Hatem Y. Diab ◽  
Mahmoud O. Abdelsalam ◽  
Mostafa I. Marei
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Control System ◽  
Distributed Generation ◽  
Control Strategy ◽  
Current Control ◽  
Operating Conditions ◽  
Pi Controllers ◽  
Artificial Neural ◽  
The Stability

This article presents a control strategy that enables both islanded and grid-tied operations of a three-phase inverter in distributed generation. This distributed generation (DG) is based on a dramatically evolved direct current (DC) source. A unified control strategy is introduced to operate the interface in either the isolated or grid-connected modes. The proposed control system is based on the instantaneous tracking of the active power flow in order to achieve current control in the grid-connected mode and retain the stability of the frequency using phase-locked loop (PLL) circuits at the point of common coupling (PCC), in addition to managing the reactive power supplied to the grid. On the other side, the proposed control system is also based on the instantaneous tracking of the voltage to achieve the voltage control in the standalone mode and retain the stability of the frequency by using another circuit including a special equation (wt = 2πft, f = 50 Hz). This utilization provides the ability to obtain voltage stability across the critical load. One benefit of the proposed control strategy is that the design of the controller remains unconverted for other operating conditions. The simulation results are added to evaluate the performance of the proposed control technology using a different method; the first method used basic proportional integration (PI) controllers, and the second method used adaptive proportional integration (PI) controllers, i.e., an Artificial Neural Network (ANN).

Research on Optimal Gradient - Climbing Algorithm in Wind Power Generation

2013 ◽  
Vol 385-386 ◽  
pp. 1100-1103 ◽  
Author(s):  
Qiang Zhao ◽  
Chang Cui
Keyword(s):  
Power Generation ◽  
Wind Power ◽  
Search Algorithm ◽  
Buck Converter ◽  
Wind Power Generation ◽  
Generation System ◽  
Load Impedance ◽  
Point Tracking ◽  
Power Generation System ◽  
Step Climbing

Maximum power point tracking for wind power generation system fixed step climbing algorithm prone to miscalculation and oscillation shortcomings. Adaptive improved optimal gradient method is put forward to overcome the shortcomings and optimize the existing fixed step climbing algorithm. By Controlling Buck Converter duty radio rapidly match between wind power generation system and load impedance. The simulation result shows that the anti-interference and convergence of the improved hill-climb search algorithm is better than that of the traditional one.

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