Efficient Generation System Research Articles

Fuzzy Controller Based Power Quality Improvement for a Microgrid with Energy Management System

There is a drastic decrease in availability of conventional energy sources such as coal, natural gas and oil. The need for using non-conventional energy sources has increased due to the fast rate depletion in conventional energy sources and the ill effects of using them. Research work in the area of renewable energy sources has hence been increased throughout the world. The rate at which power demands are increasing, requires the need for interconnections of various power generation methods. For the proper use of conventional and non-conventional distributed generation microgrid is essential. Microgrid combines one or more generation units and helps to use the power generated in efficient manner. Microgrid includes the generating units, battery storage system with power electronic converters. The use of power converter is important, but the presence of converter generates harmonics usually so that the power quality issues have become serious. Many controllers are used to solve power quality problems, where one of them is the Unified Power Quality Controller (UPQC). Problems linked to power quality become serious due to the use of power electronics appliances. Microgrid power quality is maintained by using UPQC compensating devices. To control UPQC, there must be some controller to intimate the voltage sag, swell and flickers. In this paper the fuzzy logic controller is used for UPQC. An energy management system (EMS) is a system used by electrical utility network operators to monitor, regulate and optimize transmission and generation system efficiency. The system model is created using MATLAB by merging all DC-microgrid, EMS and UPQC, to solve power quality issues.

Efficiency analysis and experimental validation of the ocean thermal energy conversion with phase change material for underwater vehicle

Underwater vehicle is one of the most important tools for ocean observation and exploration. The application of ocean thermal energy conversion can greatly extend its duration and range. The challenge in developing the system resides in the proper sizing and integration of the components to enhance the efficiency of energy conversion. This study proposes the ocean thermal energy conversion for underwater vehicles. It utilizes phase change material to collect ocean thermal energy from warm near-surface and converts it into the potential energy stored in a hydraulic accumulator, which is transformed into electrical energy for the power supply by using hydraulic motor, generator and other components. Based on its working principle, the heat to electricity power generation system efficiency model is established, and validated by comparing measurements and predictions for a laboratory system. Factors influencing the efficiency of power generation are thoroughly analyzed. Moreover, primary design guidelines based on commercially available components are deduced from the proposed model. A prototype is developed and a sea trial is conducted to validate performance of the prototype. The results show that the energy harvested by the prototype can reach 6696 J per dive cycle with 6 kg phase-change material. The maximum hydraulic-to-kinetic efficiency of about 70% and maximum kinetic-to-electric efficiency of about 80% were achieved in the system. The maximum and average energy conversion efficiency are respectively 0.55% and 0.396%. Therefore, high efficiency and good performance of prototype were validated which implied a possibility to improve the range and navigation time of underwater vehicles.

Increasing the efficiency of the passive loading strategy for wave energy conversion

The control strategy applied to the oscillating system of the wave energy converters largely determines the overall system efficiency and thus the energy production. One of the first proposed control strategies for this type of device is the passive control. This type of control continues currently to be considered because it can be implemented in a simple way: short-term predictions about the performance of the wave are not needed when passive control is applied. Moreover, the power flow is unidirectional, and the extraction system is subjected to moderate peak powers so that costs and dimensions of the wave energy converter components can be reduced. The main disadvantage of passive loading control is the low energy production compared with other control strategies, such as the so-called reactive control which requires bidirectional power flow between the oscillating system and the generator. This way, the device can extract more energy from the waves, but the global system requires large energy exchanges between the oscillating device and the generator. These energy exchanges cause high losses, and thus the overall system efficiency significantly decreases. Furthermore, the reactive control system involves high oscillating excursions that can become unacceptable. In this paper, a point absorber converter that uses a linear direct-drive generator and power electronics converters jointly is considered. This article presents a passive control strategy that optimizes the power transferred from the generator to the power electronic converter considering the copper losses in the electric generator. Applying this approach, the generation system efficiency increases significantly, and similar values of the oscillating system's heave excursions and the peak-to-average power ratio for both the conventional and the proposed passive loading are found. The formulation of the proposed method is presented as well as time domain wave-to-wire simulations in both regular and irregular waves.

Comparative study of a small size wind generation system efficiency for battery charging

This paper presents an energetic comparison between two control strategies of a small size wind generation system for battery charging. The output voltage of the direct drive PMSG is connected to the battery through a switch mode rectifier. A DC-DC boost converter is used to regulate the battery bank current in order to achieve maximum power from the wind. A maximum powertracking algorithm calculates the current command that corresponds to maximum power output of the turbine. The DC-DC converter uses this current to calculate the duty cycle witch is necessary to control the pulse width modulated (PWM) active switching device (IGPT). The system overview and modeling are presented including characteristics of wind turbine, generator, batteries, power converter, control system, and supervisory system. A simulation of the system is performed using MATLAB/SIMULINK.

Particle Swarm Optimization for Identification of PEMFC Generation System Fuzzy Model

This paper proposes particle swarm optimization (PSO) for identification of the Proton Exchange Membrane Fuel Cells (PEMFC) generation systems fuzzy model. The PEM fuel cell generation system efficiency decreases as its output power increases. Thus, an optimum efficiency should exist and should result in a cost-effective PEM fuel cell generation system. The PEMFC generation system cost and efficiency fuzzy model were build, we use the PSO as an optimization engine to indentify the fuzzy model. The simulation results were presented and the results show that we may minimize the total cost of the generation system by using the PSO.