Maximum Energy Extraction Research Articles

A Solar Panel Cleaning Robot Design and Application

Solar energy, which is one of the renewable energy sources, has an important role in meeting the increasing electrical energy demand of our globe. In recent years, many countries have established their energy policies based on solar energy, and researchers have been working on solar panel efficiency, maximum energy extraction from the sun, control and power electronics. The energy extracting from the sun is converted into electrical energy via solar panels. To extract continuously maximum energy level from the sun reduces installation costs and makes it easier to meet the demanded peak electrical power. Physical conditions such as muddy rain, snow and dusting place between the solar panel and the sun. This situation results the reduced electrical power extraction level which can be technically produced with clean solar panel surface. Therefore, it is also very important to keep the solar panels clean as well as the maximum power point tracking devices. In this study, a solar panel cleaning robot (SPCR) has been designed and tested in real time. The designed dual-motor and crawler robot moves horizontally and the cleaning brush runs on the vertical axis. In addition, the length of the solar panel array can be detected by position switches to keep the SPCR in desired working area.

Wake Characteristics and Power Performance of a Drag-Driven in-Bank Vertical Axis Hydrokinetic Turbine

Preliminary design of a new installation concept of a drag-driven vertical axis hydrokinetic turbine is presented. The device consists of a three-bladed, wheel-shaped, turbine partially embedded in relatively shallow channel streambanks. It is envisioned to be installed along the outer banks of meandering rivers, where the flow velocity is increased, to maximize energy extraction. To test its applicability in natural streams, flume experiments were conducted to measure velocity around the turbine and power performance using Acoustic Doppler Velocimetry and a controlled motor drive coupled with a torque transducer. The experiment results comprise the power coefficient, the spatial evolution of the mean velocity deficit, and a description of the flow structures generated by the turbine and responsible for the unsteadiness of the wake flow. Applying a triple decomposition on the Reynolds stresses, we identify the dominant contribution to such unsteadiness to be strongly associated with the blade passing frequency.

A Multi-Beam Shared-Inductor Reconfigurable Voltage/SECE Mode Piezoelectric Energy Harvesting Interface Circuit.

This paper presents an autonomous multi-input (multi-beam) reconfigurable power-management chip for optimal energy harvesting from weak multi-axial human motion using a multi-beam piezoelectric energy harvester (PEH). The proposed chip adaptively operates in either voltage-mode or synchronous-electrical-charge-extraction-mode (VM-SECE) to improve overall efficiency, extract maximum energy regardless of the PEH beams' impedance/voltage/frequency variations, and protect the chip against large inputs, eliminating the need for high-voltage processes. It can simultaneously harvest energy from up to 6 beams using only one shared off-chip inductor. It uses an active negative voltage converter to extend the input-voltage range to as low as 35mV. In addition, an active voltage doubler with a small footprint is implemented for faster cold start. A prototype VM-SECE chip was fabricated in a 0.35-μm 2P4M standard CMOS process occupying 1.9 mm2 active area. To fully characterize the chip performance, it was tested with both a commercial single-beam PEH and a custom-made PEH with five mechanically plucked thin-film beams. With the commercial PEH, compared to an on-chip full-wave active rectifier (FAR) with 95.6% efficiency, the VM-SECE chip harvested 3.28x more power for shock inputs at 1 Hz frequency and 4.39 g acceleration. With the custom 5-beam PEH for a pseudo-walking condition, compared to the on-chip FAR, the VM-SECE chip harvested 1.59x and 2.38x more power for 1-and 5-beam operations, respectively.

Optimization of module pressure retarded osmosis membrane for maximum energy extraction

A full-scale Pressure Retarded Osmosis process (PRO) is optimized in non-ideal operating conditions using Grey Wolf Optimization (GWO) algorithms. Optimization process included the classical parameters that previous studies recommended such as operating pressure, and feed and draw fractions in the mixture solution. The study has revealed that the recommended operating pressure ΔP=Δπ/2 and the ratio of feed or draw solution to the total mixture solution, ̴ 0.5, in a laboratory scale unit or in an ideal PRO process are not valid in a non-ideal full-scale PRO module. The optimization suggested that the optimum operating pressure is less than the previously recommended value of ΔP=Δπ/2. The optimization of hydraulic pressure resulted in 4.4% increase of the energy output in the PRO process. Conversely, optimization of feed fraction in the mixture has resulted in 28%–70% higher energy yield in a single-module PRO process and 9%–54% higher energy yield in a four-modules PRO process. The net energy generated in the optimized PRO process is higher than that in the unoptimized (normal) PRO process. The findings of this study reveal the significance of incorporating machine-learning algorithms in the optimization of PRO process and identifying the preferable operating conditions.

Maximal energy extraction via quantum measurement

We study the maximal amount of energy that can be extracted from a finite quantum system by means of projective measurements. For this quantity we coin the expression ‘metrotropy’ , in analogy with ‘ergotropy’ , which is the maximal amount of energy that can be extracted by means of unitary operations. The study is restricted to the case when the system is initially in a stationary state, and therefore the ergotropy is achieved by means of a permutation of the energy eigenstates. We show that (i) the metrotropy is achieved by means of an even combination of the identity and an involution permutation; (ii) it is , with the bound being saturated when the permutation that achieves the ergotropy is an involution.

Improved design of a DC-DC converter in residential solar photovoltaic system

<span>With growing demand in renewable energy, solar photovoltaic (PV) technology is becoming more popular. A number of research has been carried out to increase the efficiency of the PV system. One of them is improving the Switch Mode Power Supplies (SMPS) performance to ensure maximum solar energy extraction. This paper looks at buck type SMPS suitability for use in solar PV installed in residential houses. The main issues that affect the response from the output are identified. The work will utilise the LT SPICE software to carry out the simulation. The primary objective of the study is to design an improved converter controller which is more robust and is able to maintain constant output. The emphasis is on good efficiency, stability and low output voltage ripple. This could be achieved by using the current mode control (CMC) techniques – an alternative design to the voltage mode control technique (VMC). Results obtained via simulations reveal strong evidence of CMC superiority over the VMC.</span>

On osmotic heat powered cycles driven by thermal saturation-precipitation of aqueous solutions

The basis of a novel concept for osmotic heat powered cycles driven by the thermal dependence of the solubility of aqueous solutions inducing the continuous thermal precipitation/dissolution of solute is outlined. In this osmotic concept, given an aqueous solution with a temperature near to its temperature of saturation, if an external thermal input is applied (either by heating or cooling the solution depending of the specific thermal dependence of the solubility) then, partial precipitation of the solute takes place. By separating the solute precipitate from the remaining depleted solution -generally referred as supernatant, and restoring its initial temperature, the net result is the conversion and storing of thermal energy into osmotic energy contained in two streams with different salinities which can be released only when both streams are deliberately mixed by using a semi-permeable membrane. Utilizing a simplified physical model, a first estimation for the maximum extractable energy per unit of volume of solution was calculated. The specific cases for some common salts were compared. Additional R&D is required in order to arrive at a reliable practical and commercial design.

Progress of indirect drive inertial confinement fusion in the United States

Indirect drive converts high power laser light into x-rays using small high-Z cavities called hohlraums. X-rays generated at the hohlraum walls drive a capsule filled with deuterium–tritium (DT) fuel to fusion conditions. Recent experiments have produced fusion yields exceeding 50 kJ where alpha heating provides ~3× increase in yield over PdV work. Closing the gaps toward ignition is challenging, requiring optimization of the target/implosions and the laser to extract maximum energy. The US program has a three-pronged approach to maximize target performance, each closing some portion of the gap. The first item is optimizing the hohlraum to couple more energy to the capsule while maintaining symmetry control. Novel hohlraum designs are being pursued that enable a larger capsule to be driven symmetrically to both reduce 3D effects and increase energy coupled to the capsule. The second issue being addressed is capsule stability. Seeding of instabilities by the hardware used to mount the capsule and fill it with DT fuel remains a concern. Work reducing the impact of the DT fill tubes and novel capsule mounts is being pursed to reduce the effect of mix on the capsule implosions. There is also growing evidence native capsule seeds such as a micro-structure may be playing a role on limiting capsule performance and dedicated experiments are being developed to better understand the phenomenon. The last area of emphasis is the laser. As technology progresses and understanding of laser damage/mitigation advances, increasing the laser energy seems possible. This would increase the amount of energy available to couple to the capsule, and allow larger capsules, potentially increasing the hot spot pressure and confinement time. The combination of each of these focus areas has the potential to produce conditions to initiate thermo-nuclear ignition.

Analysis of filling in missing data to provide maximum power extraction in Micro Grid

An analysis of Micro Grid system performance requires both meteorological and electrical data for the assessment period. However, actual in-field data acquisition is rarely 100%, often resulting in a significant amount of incomplete datasets for performance assessment. These gaps, if not taken into account, may add noticeable bias in yield assessment and thus estimations of the lacking data need to be made. Approaches of back-filling the required data is given and validated here. This paper presents a strategy to back-fill data with good accuracy for both short and long term periods, while taking into account weather as well as system performance variations. Cases of data loss are identified. The first case is that of missing meteorological datasets, while electrical readings are available. This case is met in most small systems, either domestic or commercial, where installers reduce the cost by omitting the meteorological sensors. The second case is that of the electrical monitoring system being interrupted. The third case is a failure of both monitoring sub-systems, which could be due to communication or hardware failures. The last two cases are often met in the majority of solar farms. Two methods, by means of which it is possible to restore the missing data about the status or output current panel, are considered. The method of synthesis of meteorological data and also the method of restoration based on empirical orthogonal functions (EOFs), are considered. Method based on EOFs reconstructs missing data using empirical orthogonal functions, derived from the original data. While EOFs in a complete dataset would typically be calculated using singular value decomposition, the presence of missing data requires an iterative approach. The method allows for the estimation of missing values and full EOFs by first inserting mean values into the missing portions of the dataset and then calculating the EOFs. Because the resulting spatial EOFs and the time series of their magnitudes reconstruct the original data, a truncated version of the original dataset can be generated, using only as many EOFs as are deemed significant through validation. This provides an improved estimate of the missing information over simply inserting mean values, because the small-variance (i.e., noise) EOFs have been removed. Method of synthesis of meteorological data uses data collected from meteorological stations to estimate irradiance. Then module temperature is calculated from in-plane irradiance and ambient temperature using a simple linear thermal model. Using this information electrical performance is estimated. Two methods differ from each other, so detailed analysis and comparison of these methods are performed. The possibilities and requirements for their using are determined depending on the reasons of the loss of information in Micro Grid. The specific systems, that involve Micro Grid, in which methods can be used for providing maximum energy extraction are suggested. These two methods will be used in future research work based on applying the theory of fractals to the analysis of distributed generation systems of solar panels for maximum energy extraction.

A Self-Adapting Synchronized-Switch Interface Circuit for Piezoelectric Energy Harvesters

This paper presents a self-adapting synchronized-switch harvesting (SA-SSH) interface circuit to extract energy from vibration-based piezoelectric energy harvesters (PEHs). The implemented circuit utilizes a novel switching technique to recycle optimum amount of harvested charge on piezoelectric capacitance to strengthen the damping force, and simultaneously achieve load-independent energy extraction with a single inductor. Charge recycling is realized by adjusting extraction time, and optimized through a maximum power point tracker based on charge-flipping dissipation. The circuit has been implemented using 180 nm HV CMOS technology with 0.9 × 0.6 mm2 active area. Self-adapting SSH circuit has been validated with both macro-scaled and MEMS PEHs with different inductor values. The interface circuit provides maximum energy extraction for the full storage voltage range of 1.8–3.7 V. The implementation harnesses have 500% more power compared to an ideal full-bridge rectifier, and output 3.4 μW for 2.24 V peak-to-peak open-circuit piezoelectric voltage from MEMS PEH excited at its resonant frequency.

Parametric study of an undulating plate in a power-extraction regime

Our previous studies suggest that instead of propulsion, a body undergoing lateral traveling-wave-like motions can also work like a kinetic energy harvester which extracts energy from moving fluids including wind and water currents. Parameters including wavelength, dimensionless wave velocity and amplitude have critical effects on the energy extraction efficiencies of this type of undulating foil energy harvester. In this paper, a two-dimensional, numerical simulation of a flexible plate undergoing a traveling wave motion was then conducted. At a given dimensionless wave speed, it is found that there exits an optimum wavelength at which this type of energy harvester can extract the maximum amount of kinematic energy from the flow. Moreover, the optimum value of the wavelength increases as amplitude increases. A high efficiency area appears under the optimal combination of wavelength and amplitude. At a given amplitude, the optimal dimensionless wave speed for maximum power extraction decreases with increasing wavelength. The high efficiency area of the undulating plate resulting from the optimal combination of wavelength and wave speed is identified. At a given wave length, there is an optimal value of amplitude at which the maximum energy extraction can be achieved. In this case, a high efficiency area representing the optimal combination of amplitude and wave speed has also been discovered.

A novel P&OT-Neville’s interpolation MPPT scheme for maximum PV system energy extraction

Photovoltaic (PV) system posses an optimal operating pointing, termed as Maximum Power Point (MPP). Using Maximum Power Point Tracking (MPPT) algorithm, MPP of PV system has to be tracked continuously in any climatic conditions. In general, traditional Perturb and Observe (P&OT) MPP tracker is widely used among existing controllers. But, P&OT fails to harvest maximum power from solar panel, in addition oscillations around MPP results in low efficiency of the PV system. The contradiction involved in the traditional controller can be addressed as P&OT operates with a fixed step size. Hence, with large step size MPP can be reached quickly but the magnitude of oscillations around MPP are high. Similarly, when P&OT operated with tiny step size magnitude of oscillations can be reduced at the same time PV system consumes much time to reach MPP. In order to eliminate the contradiction involved with traditional MPPT scheme and effectively optimize PV system energy, this paper put forwards a hybrid MPPT scheme based on P&OT and Neville interpolation. The proposed scheme is executed in two stages. In the first stage, P&OT is operated with a large step size till the voltage reaches near to maximum point. In the second stage, Neville interpolation is used to find the maximum power point. The performance of the proposed scheme is compared with Golden Section Search (GSS) and P&OT MPPT controllers. With the proposed scheme the convergence time required to reach MPP is improved greatly. Experimental prototype is designed and developed to verify the performance of the proposed scheme. Experimental and simulation results provide enough evidence to show superiority of the proposed scheme.Article History: Received December 15th 2017; Received in revised form July 16th 2018; Accepted September 12th 2018; Available onlineHow to Cite This Article: Bhukya, M. N. and Kota, V. R. (2018) A Novel PandOT-Neville’s Interpolation MPPT Scheme for Maximum PV system energy extraction. International Journal of Renewable Energy Development, 7(3), 251-262https://dx.doi.org/10.14710/ijred.7.3.251-26

A novel P&OT-Neville’s interpolation MPPT scheme for maximum PV system energy extraction

Photovoltaic (PV) system posses an optimal operating pointing, termed as Maximum Power Point (MPP). Using Maximum Power Point Tracking (MPPT) algorithm, MPP of PV system has to be tracked continuously in any climatic conditions. In general, traditional Perturb and Observe (P&OT) MPP tracker is widely used among existing controllers. But, P&OT fails to harvest maximum power from solar panel, in addition oscillations around MPP results in low efficiency of the PV system. The contradiction involved in the traditional controller can be addressed as P&OT operates with a fixed step size. Hence, with large step size MPP can be reached quickly but the magnitude of oscillations around MPP are high. Similarly, when P&OT operated with tiny step size magnitude of oscillations can be reduced at the same time PV system consumes much time to reach MPP. In order to eliminate the contradiction involved with traditional MPPT scheme and effectively optimize PV system energy, this paper put forwards a hybrid MPPT scheme based on P&OT and Neville interpolation. The proposed scheme is executed in two stages. In the first stage, P&OT is operated with a large step size till the voltage reaches near to maximum point. In the second stage, Neville interpolation is used to find the maximum power point. The performance of the proposed scheme is compared with Golden Section Search (GSS) and P&OT MPPT controllers. With the proposed scheme the convergence time required to reach MPP is improved greatly. Experimental prototype is designed and developed to verify the performance of the proposed scheme. Experimental and simulation results provide enough evidence to show superiority of the proposed scheme.Article History: Received December 15th 2017; Received in revised form July 16th 2018; Accepted September 12th 2018; Available onlineHow to Cite This Article: Bhukya, M. N. and Kota, V. R. (2018) A Novel PandOT-Neville’s Interpolation MPPT Scheme for Maximum PV system energy extraction. International Journal of Renewable Energy Development, 7(3), 251-260https://dx.doi.org/10.14710/ijred.7.3.251-260

RETRACTED ARTICLE: Wind Farm Layout Design Using Cuckoo Search Algorithms

ABSTRACTWind energy has emerged as a strong alternative to fossil fuels for power generation. To generate this energy, wind turbines are placed in a wind farm. The extraction of maximum energy from these wind farms requires optimal placement of wind turbines. Due to complex nature of micrositing of wind turbines, the wind farm layout design problem is considered a complex optimization problem. In the recent past, various techniques and algorithms have been developed for optimization of energy output from wind farms. The present study proposes an optimization approach based on the cuckoo search (CS) algorithm, which is relatively a recent technique. A variant of CS is also proposed that incorporates a heuristic-based seed solution for better performance. The proposed CS algorithms are compared with genetic and particle swarm optimization algorithms which have been extensively applied to wind farm layout design. Empirical results indicate that the proposed CS algorithms outperformed the genetic and particle swarm optimization algorithms for the given test scenarios in terms of yearly power output and efficiency.

Energy-maximising control of wave energy converters using a moment-domain representation

Wave Energy Converters (WECs) have to be controlled to ensure maximum energy extraction from waves while considering, at the same time, physical constraints on the motion of the real device and actuator characteristics. Since the control objective for WECs deviates significantly from the traditional reference “tracking” problem in classical control, the specification of an optimal control law, that optimises energy absorption under different sea-states, is non-trivial. Different approaches based on optimal control methodologies have been proposed for this energy-maximising objective, with considerable diversity on the optimisation formulation. Recently, a novel mathematical tool to compute the steady-state response of a system has been proposed: the moment-based phasor transform. This mathematical framework is inspired by the theory of model reduction by moment-matching and considers both continuous and discontinuous inputs, depicting an efficient and closed-form method to compute such a steady-state behaviour. This study approaches the design of an energy-maximising optimal controller for a single WEC device by employing the moment-based phasor transform, describing a pioneering application of this novel moment-matching mathematical scheme to an optimal control problem. Under this framework, the energy-maximising optimal control formulation is shown to be a strictly concave quadratic program, allowing the application of well-known efficient real-time algorithms.

Independent caudal fin actuation enables high energy extraction and control in two-dimensional fish-like group swimming

We study through numerical simulation the optimal hydrodynamic interactions and basic vorticity control mechanisms for two fish-like bodies swimming in tandem. We show that for a fish swimming in the wake of an upstream fish, using independent pitch control of its caudal fin, in addition to optimized body motion, results in reduction of the energy needed for self-propulsion by more than 50 %, providing a quasi-propulsive efficiency of 90 %, up from 60 % without independent caudal fin control. Such high efficiency is found over a narrow parametric range and is possible only when the caudal fin is allowed to pitch independently from the motion of the main body. We identify the vorticity control mechanisms employed by the body and tail to achieve this remarkable performance through thrust augmentation and destructive interference with the upstream fish-generated vortices. A high sensitivity of the propulsive performance to small variations in caudal fin parameters is found, underlying the importance of accurate flow sensing and feedback control. We further demonstrate that using lateral line-like flow measurements to drive an unscented Kalman filter, the near-field vortices can be localized within 1 % of the body length, and be used with a phase-lock controller to drive the body and tail undulation of a self-propelled fish, moving within the wake of an upstream fish, to stably reach the optimal gait and fully achieve maximum energy extraction.

Numerical study on extracting energy efficiency by autorotation of elliptic cylinder from low velocity flow

A new concept of power generator using autorotation of elliptic cylinder to extract energy from fluid is proposed in the present study. Numerical simulation studies Fluid-Structure Interaction of the fixed-axis autorotation of rigid elliptic cylinder using a coupled Computational Fluid Dynamics (CFD) – Rigid Body Dynamics (RBD) solver. This solver requires no solid mesh to setup FSI (Fluid Structure Interaction) simulation. Based on solving two-dimensional unsteady incompressible N-S equations and SST k-ω turbulent governing equations, the power generator of elliptic cylinder was investigated in different axis rations, eccentric distance ratios and Reynolds number conditions. Numerical results reveal that autorotation of elliptic cylinder can achieve energy extraction. With optimal parameters, the power generator can reach maximum energy extraction efficiency of 34%. The investigation results provided fundamental support for utilization of ocean current energy.

Optimum design of a small wind turbine blade for maximum power production

The rotor blades of a wind turbine are critical components that consist of aerodynamic shapes called airfoils. The interaction of these airfoils with the wind allows converting the power in the wind to mechanical power. The structure of the rotor blades must be able to extract maximum energy from the wind while being strong enough to stand steady, periodic and randomly changing loads. For maximum power extraction, an optimum design of the rotor blades is necessary. This paper presents a typical design methodology of the rotor blades of a small wind turbine with a power generation of 11 kW (rotor radius of 3.5 m). First, the design parameters were presented. Then, optimum blade geometry (chord length and twist angle distribution) was determined using optimum rotor theory. Finally, the wind turbine blade performance (power coefficient and power production) was assessed using Q-blade software.

MPPT in PV systems under partial shading conditions using artificial vision

Maximum power point tracking (MPPT) algorithms should track and extract the maximum power from photovoltaic (PV) systems under any environmental conditions. Most of conventional MPPT methods are able to reach the maximum point when there is only one peak in the P–V characteristic curve but they fail when the solar cells are affected by partial shading conditions due to the fact that multiple peaks appear in the P–V curve. Thus, a local maximum may be reached instead of the global peak. In this work, a new method to accomplish the maximum power point (MPP) under partial shading conditions using artificial vision is presented. The artificial vision uses a webcam to identify in real time the shadow irradiance and provide the reference voltage that supplies the maximum power, regardless of the number of peaks that the P–V curve presents. Then, the reference voltage is used by a robust and non-linear control, the backstepping controller, to regulate the DC/DC converter input voltage and to guarantee the PV modules maximum energy extraction. Experimental tests carried out outdoor validate the proposed method, obtaining a MPP tracking efficiency that ranges from 98.1% to 99.6%.

Compact millijoule diode-seeded two-stage fiber master oscillator power amplifier using a multipass and forward pumping scheme.

The multipass scheme for a diode-seeded fiber master oscillator power amplifier with a nanojoule-to-millijoule output energy level at a repetition rate of <100 kHz is numerically analyzed for comparison to an experimental benchmark. For a 6/125 single-mode preamplifier with a small input energy (<1 nJ), there is a significant improvement in the output energy from 0.7% to 80% and 95% of the maximum extractable energy using the double-pass and four-pass schemes, respectively. For a 30/250 large-mode-area power amplifier using the double-pass and forward pumping scheme, the required input energy is decreased from 100μJ to 18μJ for millijoule energy extraction with accompanying Stokes waves of less than 10% of the total energy. The system based on the full master oscillator power amplifier configuration with an output energy exceeding millijoule level can be optimally simplified to two stages for commercialization.