The immersed boundary method has emerged as an efficient approach for the simulation of finite-sized solid particles in complex fluid flows.However,one of the well known shortcomings of the method is the limited suppo...The immersed boundary method has emerged as an efficient approach for the simulation of finite-sized solid particles in complex fluid flows.However,one of the well known shortcomings of the method is the limited support for the simulation of light particles,i.e.particles with a density lower than that of the surrounding fluid,both in terms of accuracy and numerical stability.Although a broad literature exists,with several authors reporting different approaches for improving the stability of the method,most of these attempts introduce extra complexities and are very costly from a computational point of view.In this work,we introduce an effective force stabilizing technique,allowing to extend the stability range of the method by filtering spurious oscillations arising when dealing with light-particles,pushing down the particle-to-fluid density ratio as low as 0.04.We thoroughly validate the method comparing with both experimental and numerical data available in literature.展开更多
The penetration of renewable energy sources(RESs)in the distribution system becomes a challenge for the reliable and safe operation of the existing power system.The sporadic characteristics of sustainable energy sourc...The penetration of renewable energy sources(RESs)in the distribution system becomes a challenge for the reliable and safe operation of the existing power system.The sporadic characteristics of sustainable energy sources along with the random load variations greatly affect the power quality and stability of the system.Hence,it requires storage systems with both high energy and high power handling capacity to coexist in microgrids.An efficient energy management structure is designed in this paper for a grid-connected PV system combined with hybrid storage of supercapacitor and battery.The combined supercapacitor and battery storage system grips the average and transient power changes,which provides a quick control for the DC-link voltage,i.e.,it stabilizes the system and helps achieve the PV power smoothing.The average power distribution between the power grid and battery is done by checking the state of charge(SOC)of a battery,and an effective and efficient energy management scheme is proposed.Additionally,the use of a supercapacitor lessens the current stress on the battery system during unexpected disparity in the generated power and load requirement.The performance and efficacy of the proposed energy management scheme are justified by simulation studies.展开更多
Partly because of advances in power electronic converters,the share of renewable energy in power generation is steadily increasing.The main medium of interface for integrating renewable energy sources to the utility g...Partly because of advances in power electronic converters,the share of renewable energy in power generation is steadily increasing.The main medium of interface for integrating renewable energy sources to the utility grid is the power electronic inverter.Virtual oscillator control(VOC)is a time-domain approach for controlling parallel inverters in a standalone microgrid(MG).The concept is to simulate nonlinear deadzone oscillator dynamics in a system of invert-ers to ensure a stable AC MG in the absence of communication.VOC is a time-domain and self-synchronizing control-ler that simply requires the measurement of filter current,whereas traditional droop control and the virtual synchro-nous machine(VSM)require low pass filters for active and reactive power calculations.In this work,a particle swarm optimization(PSO)-based VOC method(VOC-PSO)is proposed,in which the parameters of the VOC are designed using the PSO algorithm.The system performance using droop,VSM,VOC,and VOC-PSO controllers are investigated using MATLAB and Opal-RT real-time digital simulator platforms.The results show that the proposed VOC-PSO gives improved performance over other control strategies.The efficacy of the proposed VOC-PSO control method is also demonstrated by the experimental results.展开更多
文摘The immersed boundary method has emerged as an efficient approach for the simulation of finite-sized solid particles in complex fluid flows.However,one of the well known shortcomings of the method is the limited support for the simulation of light particles,i.e.particles with a density lower than that of the surrounding fluid,both in terms of accuracy and numerical stability.Although a broad literature exists,with several authors reporting different approaches for improving the stability of the method,most of these attempts introduce extra complexities and are very costly from a computational point of view.In this work,we introduce an effective force stabilizing technique,allowing to extend the stability range of the method by filtering spurious oscillations arising when dealing with light-particles,pushing down the particle-to-fluid density ratio as low as 0.04.We thoroughly validate the method comparing with both experimental and numerical data available in literature.
文摘The penetration of renewable energy sources(RESs)in the distribution system becomes a challenge for the reliable and safe operation of the existing power system.The sporadic characteristics of sustainable energy sources along with the random load variations greatly affect the power quality and stability of the system.Hence,it requires storage systems with both high energy and high power handling capacity to coexist in microgrids.An efficient energy management structure is designed in this paper for a grid-connected PV system combined with hybrid storage of supercapacitor and battery.The combined supercapacitor and battery storage system grips the average and transient power changes,which provides a quick control for the DC-link voltage,i.e.,it stabilizes the system and helps achieve the PV power smoothing.The average power distribution between the power grid and battery is done by checking the state of charge(SOC)of a battery,and an effective and efficient energy management scheme is proposed.Additionally,the use of a supercapacitor lessens the current stress on the battery system during unexpected disparity in the generated power and load requirement.The performance and efficacy of the proposed energy management scheme are justified by simulation studies.
基金supported by DST project Scheme for Young Scientists and Technologists (SP/YO/2019/1349).
文摘Partly because of advances in power electronic converters,the share of renewable energy in power generation is steadily increasing.The main medium of interface for integrating renewable energy sources to the utility grid is the power electronic inverter.Virtual oscillator control(VOC)is a time-domain approach for controlling parallel inverters in a standalone microgrid(MG).The concept is to simulate nonlinear deadzone oscillator dynamics in a system of invert-ers to ensure a stable AC MG in the absence of communication.VOC is a time-domain and self-synchronizing control-ler that simply requires the measurement of filter current,whereas traditional droop control and the virtual synchro-nous machine(VSM)require low pass filters for active and reactive power calculations.In this work,a particle swarm optimization(PSO)-based VOC method(VOC-PSO)is proposed,in which the parameters of the VOC are designed using the PSO algorithm.The system performance using droop,VSM,VOC,and VOC-PSO controllers are investigated using MATLAB and Opal-RT real-time digital simulator platforms.The results show that the proposed VOC-PSO gives improved performance over other control strategies.The efficacy of the proposed VOC-PSO control method is also demonstrated by the experimental results.
