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1,737 results on '"Lei, Yun"'

55. Photovoltaic power prediction based on improved grey wolf algorithm optimized back propagation

Author

Ping He, Jie Dong, Xiaopeng Wu, Lei Yun, and Hua Yang

Subjects
bp neural network, photovoltaic power generation, pso–gwo model, pso–gwo–bp prediction model, standard grey wolf algorithm, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

At present, the back-propagation (BP) network algorithm widely used in the short-term output prediction of photovoltaic power stations has the disadvantage of ignoring meteorological factors and weather conditions in the input. The existing traditional BP prediction model lacks a variety of numerical optimization algorithms, such that the prediction error is large. The back-propagation (BP) neural network is easy to fall into local optimization thus reducing the prediction accuracy in photovoltaic power prediction. In order to solve this problem, an improved grey wolf optimization (GWO) algorithm is proposed to optimize the photovoltaic power prediction model of the BP neural network. So, an improved grey wolf optimization algorithm optimized BP neural network for a photovoltaic (PV) power prediction model is proposed. Dynamic weight strategy, tent mapping and particle swarm optimization (PSO) are introduced in the standard grey wolf optimization (GWO) to construct the PSO–GWO model. The relative error of the PSO–GWO–BP model predicted data is less than that of the BP model predicted data. The average relative error of PSO–GWO–BP and GWO–BP models is smaller, the average relative error of PSO–GWO–BP model is the smallest, and the prediction stability of the PSO–GWO–BP model is the best. The model stability and prediction accuracy of PSO–GWO–BP are better than those of GWO–BP and BP.

Published
2023
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88. Smooth Regulation of DC Voltage in VSC-MTDC Systems Based on Optimal Adaptive Droop Control

Author

Ping He, Xiaowei Zhang, Congshan Li, Lei Yun, Hua Yang, and Yabang Yan

Subjects
DC voltage deviation, droop control, power margin, VSC-MTDC, Engineering (General). Civil engineering (General), TA1-2040
Abstract

DC voltage stability and power balance are the key conditions for stable operation of DC transmission systems. The droop control does not depend on inter-station communication and has the advantage of multi-station cooperative unbalanced power dissipation, which has been widely used in the voltage source converter based multi-terminal direct current (VSC-MTDC) system. However, its control will cause DC voltage deviation, and there are a series of problems such as unstable system control and overload operation of the VSC-station due to improper setting of droop coefficient. In this paper, the infeasibility of DC voltage error-free correction under droop control mode is theoretically analyzed, and a VSC-MTDC cooperative optimization droop control strategy with DC voltage "quasi-error-free" adjustment ability is proposed. The strategy adjusts the droop coefficient in real-time by monitoring the DC voltage deviation and the power margin of the VSC-station to solve the problem of voltage deviation caused by unbalanced power consumption. At the same time, an additional DC voltage stabilizer is designed to automatically adjust the power reference value and restore the DC voltage. Finally, a five-terminal VSC-MTDC system is built under PSCAD/EMTDC to verify the feasibility of the proposed strategy.

Published
2023
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98. Micro-nanoarchitectonics of Electroless Cu/Ni Composite Materials Based on Wood via Heat Treatment

Author

Yanfei Pan, Mayin Dai, Xin Zheng, Lei Yun, Fengqi Qiu, Dongbo Yang, Caiyi Deng, Qiang Guo, and Jintian Huang

Subjects
wood, electroless cu-ni, conductivity, hydrophobicity, electromagnetic shielding, Biotechnology, TP248.13-248.65
Abstract

This research aims to optimize the comprehensive performance of wood-based electromagnetic shielding interference (EMI) materials and master the effect of heat treatment on its coating density, interfacial morphology, conductivity, and hydrophobic and electromagnetic shielding. The results showed that the surface roughness of composite coatings was 11.0 μm when the wood was conducted via electroless two deposition Cu and one Ni and the heat treatment temperature was 150 °C. The composite coating’s surface gradually became more uniform with increasing temperature. The coating’s thickness via 120 °C heat treatment was 97.5 μm. Energy Dispersive Spectroscopy (EDS) spectra verified the existence of Cu and Ni particles. The heat treatment had an obvious influence on conductivity of composite materials and the pore network structure. The contact angle of composite materials reached 119°. The average electromagnetic shielding efficiency via 180 °C heat treatment was up to 91.4 dB in the frequency ranging from 300 to 3.0 GHz, which verified that the composite materials can shield 99.99% of the incident electromagnetic wave energy. The conductivity gradient structure can realize multi-dielectric interface loss and multiple reflection loss.

Published
2022

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