Maximum Power Variation Research Articles

High-order tunable multi-wavelength random Raman fiber laser based on few-mode fiber filter

In recent years, multi-wavelength fiber lasers have become one of the research hotspots and have been extensively applied in optical fiber communication systems. However, the presented multi-wavelength fiber lasers mainly operate in the 1.5 μm band. In this paper, a few-mode fiber filter-based cascaded high-order tunable multi-wavelength random Raman fiber laser (MWRRFL) is demonstrated, for the first time, in which a tuning range covers the 1.1–1.5 μm band. In the half-open MWRRFL, a few-mode fiber-based intermodal interferometer filter is inserted in the point reflector as a wavelength selector. The synergetic effect including high Raman gain and Rayleigh backscattering intensity in the hybrid of dispersion-shifted fiber and standard single-mode fiber is employed. It presents the capability for flat multi-wavelength random lasing stimulation. As a result, the wavelength channel number of the 6th-order random lasing is 6, with a maximum power variation of 4.66 dB and good temporal stability. The proposed cascaded tunable MWRRFL could provide a versatile source for optical fiber communication, optical fiber sensing, spectrum analysis, etc.

Experimental and numerical study on a novel thermal mass flowmeter that is insensitive to radial flow velocity distribution

A novel thermal mass flowmeter (TMF) is proposed by improving the composition and structure of the probe in this study. An experimental setup was developed to compare the effects of installation angles on the measurement characteristics of the novel and traditional TMF (flow velocity range of 1.0–8.0 m/s), and three-dimensional numerical models were established to compare the effects of axial positions and insertion depths on the measurement characteristics of novel and traditional TMF (flow velocity range of 0.05–8.0 m/s). The experimental results show that when the installation angle changes from 0° to 90°, the maximum power variation of traditional TMF is 16.5%, while that of the novel TMF is only 0.6%. The simulation results show that when the axial position changes from 9 to 1 m, the maximum power variation of traditional TMF is 11.5%, while that of the novel TMF is only 3.8%. When the insertion depth of the velocity sensor translates from the pipe center to 0.10 m upward, the maximum power variation of traditional TMF is 91.6%. The novel TMF is installed by thread or flange compression, with a fixed and unique insertion depth of D/2, there is no change in the insertion depth during measurement. In conclusion, the effect of the flow velocity distribution on the measurement characteristics is significantly reduced in the novel TMF compared to the traditional TMF, the measurement results are more accurate.

Modeling of hydrogen production system for photovoltaic power generation and capacity optimization of energy storage system

Hydrogen production using solar energy is an important way to obtain hydrogen energy. However, the inherent intermittent and random characteristics of solar energy reduce the efficiency of hydrogen production. Therefore, it is necessary to add an energy storage system to the photovoltaic power hydrogen production system. This paper establishes a model of a photovoltaic power generation hydrogen system and optimizes the capacity configuration. Firstly, the mathematical model is modeled and analyzed, and the system is modeled using Matlab/Simulink; secondly, the principle of optimal configuration of energy storage capacity is analyzed to determine the optimization strategy, we propose the storage capacity configuration algorithm based on the low-pass filtering principle, and optimal time constant selection; finally, a case study is conducted, whose photovoltaic installed capacity of 30 MW, verifying the effectiveness of the proposed algorithm, analyzing the relationship between energy storage capacity and smoothing effect. The results show that as the cut-off frequency decreases, the energy storage capacity increases and the smoothing effect is more obvious. The proposed algorithm can effectively reduce the 1 h maximum power variation of PV power generation. In which the maximum power variation of PV generation 1 h before smoothing is 4.31 MW. We set four different sets of time constants, the maximum power variation of PV generation 1 h after smoothing is reduced to 0.751, 0.389, 0.078, and 0.04 MW, respectively.

Two-Coil Receiver for Electrical Vehicles in Dynamic Wireless Power Transfer

Dynamic wireless power transfer (DWPT) of electric vehicles (EVs) is the future of urban mobility. The DWPT is often based on a series of short track pads embedded in road pavement that wirelessly transfers electrical energy to EVs equipped with a pickup coil for battery charging. An open problem with this technology is the variation of the coupling factor as a vehicle switches from one transmitting coil to another during its motion. This can cause a significant change in power with possible power spikes and holes. In order to overcome these issues, a new architecture is here proposed based on two pick-up coils mounted in the vehicle underneath. These identical receiver coils are placed in different positions under the vehicle (one in front and the other in the rear) and are activated one at a time so that inductive coupling is always good enough. This innovative configuration has two main advantages: (i) it maintains a nearly constant coupling factor, as well as efficiency and transferred power, as the vehicle moves along the electrified road; (ii) it significantly reduces the cost of road infrastructure. An application is presented to verify the proposed two-coil architecture in comparison with the traditional one-coil. The results of the investigation show the significant improvement achieved in terms of maximum power variation which is nearly stable with the proposed two-coil architecture (only 2.8% variation) while there are many power holes with the traditional single coil architecture. In addition, the number of the required transmitting coils is significantly reduced due to a larger separation between adjacent coils.

Simulation on plateau power recovery of turbocharged diesel engine matched with electronic unit pump

Aiming at the problem of power reduction of supercharged diesel engine equipped with electronic unit pump in plateau operation, a simulation model is established by using onedimensional software BOOST. Under the condition that the maximum combustion pressure and exhaust temperature are basically unchanged, the variation of maximum power, optimal injection advance angle and excessive air coefficient with inlet absolute pressure at typical speed is analyzed, which has important guiding significance for the control strategy of diesel engine in plateau operation.

Performance Improvement of a Low-Power Wind Turbine Using Conical Sections

This paper examines the performance of conical sections (concentrator and diffuser) to improve the energy-recovery prospects of small-scale wind turbines. Detailed simulation studies of the conical sections with convergence angle viz., concentrator, and divergence angle viz., diffuser were conducted using ANSYS Fluent® software. Using simulation data, a trend analysis was conducted, and the empirical equations were derived for calculating the velocity variation and power variation in terms of the convergence/divergence angles. Working prototype models with optimum angles were fabricated for both the diffuser and concentrator. These models were then augmented with a wind turbine coupled with a 100 W, 24 V DC generator and tested to validate the simulation results. Upon analyzing the simulation data, it was found that a maximum velocity variation of 23.3% was achieved at an angle of 4.5° for the diffuser, whereas a maximum power variation of 65.1% was achieved at an angle of 3.6° for the same diffuser. The aforementioned improvement was achieved by optimizing divergence angle alone. The proposed designs of the diffuser- and concentrator-augmented wind turbine, as well as the empirical equations for calculating the velocity variation and power variation in terms of the divergence and convergence angle, are the major contributions of this article.

TVACPSO-assisted analysis of the effects of temperature and irradiance on the PV module performances

The time-varying acceleration coefficients particle swarm optimization method is employed to extract the physical parameters of the single diode PV model. Under the condition of low radiation and high temperature, there is a slight deviation between the calculated and the published data, but this model still has good accuracy in most ranges. The time-varying mechanism is introduced to mitigate the premature convergence problem and establish an appropriate tradeoff between the explorative and exploitative capabilities. The method provides the lowest cost function in the extraction of parameters. Although the experimental conditions of the curves cannot fully represent the working environment of the photovoltaic module, the validity of the model can be verified by comparing the calculated curves with the released curves. Analytical solutions of short-circuit current, open-circuit voltage, maximum power point current and voltage are also derived by the Lambert W function. The variation of maximum power, fill factor, energy efficiency, exergy efficiency and power conversion efficiency of the multi-crystalline and thin-film modules in the range of 10–70 °C were studied. The electrical performance of PV modules is more sensitive to temperature than irradiance. The output performance of thin-film modules is better than crystalline modules at high temperature conditions.

Al/Air 연료전지의 출력특성에 미치는 KOH 전해질과 H<sub>2</sub>O<sub>2</sub> 감극제의 영향

The effects of additive such as H₂O₂ in KOH electrolyte solution for the Aluminum/Air fuel cell were investigated with regard to electric power characteristics. The power generated by a Al/Air fuel cell was controlled by the KOH electrolyte solution and H₂O₂ depolarizer. Higher cell power was achieved when higher KOH electrolyte concentration and higher H₂O₂ depolarizer amount. The maximum power was increased by the increase amount H₂O₂ depolarizer, it was found that H₂O₂depolarizer inhibits the generation of hydrogen and the polarization effect was reduced as a result. Internal resistance analysis was employed to elucidate the maximum power variation. Higher internal resistance created internal potential differences that drive current dissipating energy. In order to improve the output characteristics of the Al/Air fuel cell, it is thought to be desirable to increase the KOH electrolyte concentration and increase the H₂O₂ addition amounts.

Simulations of hybrid system varying solar radiation and microturbine response time

Hybrid power systems, such as combinations of renewable power sources with intermittent power production and non-renewable power sources, theoretically increase the reliability and thus integration of renewable sources in the electrical system. However, a recent increase in the number of hybrid installations has sparked interest in the effects of their connection to the grid, especially in remote areas. This paper analyses a photovoltaic-gas microturbine hybrid system dimensioned to be installed in La Paz (Mexico).The research presented in this paper studies and quantifies the effects on the total electric power produced, varying both the solar radiation and the gas microturbine response time. The gas microturbine and the photovoltaic panels are modelled using Matlab/Simulink software, obtaining a platform where different tests to simulate real conditions have been executed. They consist of diverse ramps of irradiance that replicate solar radiation variations, and different microturbine response times reproduced by the time constants of a first order transfer function that models the microturbine dynamic response. The results obtained show that when radiation varies quickly it does not produce significant differences in the power guarantee or the microturbine gas consumption, to any microturbine response time. However, these two parameters are highly variable with smooth radiance variations. The maximum total power variation decreases greatly as the radiation variation gets lower. In addition, by decreasing the microturbine response time, it is possible to appreciably increase the power guarantee although the maximum power variation and gas consumption increase. Only in cases of low radiation variation is there no appreciable difference in the maximum power variation obtained by the different turbine response times.

Passive Monitoring of the Power Generated in Grid Connected PV Systems.

This paper presents a methodology associated to a set of explicit equations aimed to translate point-to-point the generated power to standard test conditions and its application to a real situation. Such equations are employed for monitoring and diagnostic of grid connected photovoltaic systems. The proposed method is based in the data analysis through statistical methods and it allows diagnosis or detection of instant decreases of generated power. The Experimental results are compared with other procedure of characterization of the nominal power of large photovoltaic generators under real operation conditions which are based on protocols similar to the one proposed in this paper. Results show differences less to 3% between both methods. In conclusion, the methodology presented is useful for real time diagnose of power decrease, when variation of maximum power with temperature is not known or in cases where catalog parameters are not available.

Investigation of In-Band OSNR Monitoring Technique Using Power Ratio

We propose and demonstrate an in-band optical signal-to-noise ratio (OSNR) monitoring technique using the output power ratio (PR) of the nonlinear optical loop mirror (NOLM) theoretically and experimentally. Operation point (OP) is investigated to be the input average power which corresponds to the first maximum of the power ratio curve. The monitoring performances using PR are proved to be better than those just using one output port of NOLM for on-off keying (OOK) and differential phase-shift-keying (DPSK) signals with different duty cycles: non-return-to-zero (NRZ), carrier-suppressed return-to zero (CSRZ), return-to-zero (RZ) with 50% and 33% duty cycle (RZ 50 and RZ 33) at 40 Gb/s. For 80 Gb/s RZ-differential quadrature phase-shift keying (DQPSK) signal, we obtained 12.16 dB maximum power variation and 13-39.8 dB monitoring range experimentally. The power ratio scheme can improve the contrast ratio by 7.05 dB and the monitoring range by 13.8 dB compared with that just using the transmission port. The tolerance to residual chromatic dispersion of the monitoring performance is investigated to be less than 1.7 ps/nm. The experimental validations are consistent with the theoretical analyses. The proposed scheme can be used in ultra-speed transmission systems.

23 wavelength with 100 GHz spacing comb generator source

Simultaneous oscillation of 23 wavelengths, spaced at 100 GHz, is demonstrated from a single source using a semiconductor optical amplifier linear cavity. The wavelength comb is generated from an intra cavity, fiber implemented Lyot filter. Each oscillating wavelength has a linewidth of 12.5 GHz and the maximum power variation between the 23 wavelengths was less than 3 dB.

Dynamical power-equalized fiber laser arrays using strain-tunable pump reflectors

By using strain-tunable gratings as pump reflectors for power equalization, both the parallel and serial types, pump-shared linear cavity laser arrays are produced. A 11-channel, parallel type fiber laser arrays are used to simulate the feasibility. After the central reflected wavelengths of these pump reflectors are appropriately adjusted, the maximum power variation among channels is reduced from 7.2- to 0.1 dB and the average output power is nearly 100% increased.

Parallel pump-shared linear cavity laser array using 980-nm pump reflectors or N pieces of gain fibers as self-equalizers

By using fiber gratings as pump reflectors with various reflectivities or N pieces of gain fibers with various lengths externally to linear cavity as self-equalizers, a parallel-type, pump-shared linear cavity laser array (LCLA) is proposed and numerically studied. The average output power is increased and the maximum power variation among channels is reduced from 7.2 to less than 0.1 dB when the reflectivity of each pump reflector or the length of each gain fiber is adjusted appropriately.

Power-equalized parallel-type pump-shared fiber lasers based on parameter-adjustment

A parallel-type, pump-shared (PTPS) scheme linear-cavity laser array (LCLA) is proposed and numerically studied. Power-equalization of multiwavelength fiber lasers can be achieved by varying the pumping power ratio, length of the erbium-doped fiber or reflectivity of grating reflector for the individual channels. Before and after power-equalization, the maximum power variation among seven equal-spaced channels, ranging from 1530 to 1560 nm, is 5.8 and 0.2 dB, respectively.

Analysis and Simulation of Storm Induced WECS Generation Changes on System Operation

The effects of large rapid changes in generation from large arrays of wind turbine generators on the operation of automatic generation control (AGC) and frequency regulation will be assessed. The theoretical worst case change and rates of change of generation from an array of wind turbines due to passage of a thunderstorm front is given for a coastal farm. Constraints on the penetration of the portion of an echelon and farm that are affected by the front are derived so that power variation rates from a farm satisfying these constraints will not exceed the response rate capability of a typical system. These penetration constraints would eliminate the occurrence of excessive frequency excursions and violations of NAPSIC performance requirements on automatic generation control. The penetration constraints effect on the size of an array and the maximum power variation rates allowed on a particular system are discussed. The effects of simultaneous load and Wind Electric Conversion System (WECS) generation changes on automatic generation control, frequency regulation, and economic dispatch are then determined via simulation. It is shown that the total of load and WECS generation change in a ten minute interval must be less than load following capability for that period or a severe saturation problem occurs. A cycling problem is shown to occur if storm induced WECS generation change will cause frequency deviations that exceed governor deadband.

Pulsed megawatt X-band klystron

Development of a broadband, long pulse, high power klystron at X-band is discussed. The electrical design, performance, and the construction of the tube are presented. The tube has a peak power output of 1.25 MW and an average power output of 6 KW. Bandwidth of the tube is 4 percent with a maximum power variation of 1 db. A seven cavity stagger-tuned tube was developed in order to realize 47 db large signal gain and 4 percent bandwidth. The correlation between the expected performance and theactual performance will be noted. The mechanical design of the tube and the method of assembly will be discussed. A number of window designs and materials were investigated for handling the high r-f voltage gradients at the output.