Multiple architecture system for wind speed prediction

A new approach based on multiple architecture system (MAS) for the prediction of wind speed is proposed. The motivation behind the proposed approach is to combine the complementary predictive powers of multiple models in order to improve the performance of the prediction process. The proposed MAS can be implemented by associating the predictions obtained from the different regression algorithms (MLR, MLP, RBF and SVM) making up the ensemble by three fusion strategies (simple, weighted and non-linear). The efficiency of the proposed approach has been assessed on a real data set recorded from seven locations in Algeria during a period of 10 years. The experimental results point out that the proposed MAS approach is capable of improving the precision of the wind speed prediction compared to the traditional prediction methods.     

一种基于主成分分析与支持向量机的风电齿轮箱故障诊断方法

为解决风电齿轮箱状态监测数据样本量较少,特征指标间存在相互干扰且具有非线性难以分类等问题,本文提出了一种基于主成分分析结合支持向量机的风电齿轮箱故障诊断方法。首先,采用主成分分析法(PCA)对原始数据进行降维,做出第1,2主成分二维图及前3个主成分三维图,表明PCA对监测状态数据具有一定的分类效果。其次,提取累计贡献率80%以上的前5个主成分作为数据集。最后,采用支持向量机(SVM)比较4种不同核函数的诊断准确度,并加入噪声验证。分析结果表明：径向基核函数构建的支持向量机总体分类精度达到97%,准确率最高;在含噪的情况下,线性核函数与径向基核函数分类精度达到94%;与MLP神经网络进行对比发现,支持向量机更适应小样本分析且测试精度较高。实例分析表明,主成分分析结合支持向量机有较好的分类效果,适用于风电齿轮箱故障诊断的工程应用。     

基于SVM方法的风电场短期风速预测

针对基于支持向量机的风电场短期风速预测进行研究．选择了不同的输入向量（历史风速时间序列,历史风速和温度．历史风速、温度和风向,历史风速、温度和时间）作为输入进行误差对比分析。实测数据及分析结果表明,采用历史风度和温度的二输入模型,预测效果最佳,为风速的短期预测和发电量预测提供了较好的参考价值。     

基于SSA-PSO-ANFIS的短期风速预测研究

针对风速具有强非线性的特点,提出一种奇异谱分析和改进粒子群优化自适应模糊推理系统的短期风速预测模型。该方法采用奇异谱分析将原始序列分解为趋势和谐波分量,对各分量分别建立模糊神经网络模型,最后将各分量预测结果叠加得到预测风速值。为提高预测精度,改用改进粒子群算法对自适应模糊推理系统的隶属度函数进行优化。以河北某风电场实测数据进行仿真并与传统的神经网络对比分析,结果表明将风速重构后分别预测再叠加降低了原始问题的复杂度,同时提高了预测精度,在不同时间间隔的风速序列预测中该模型显著降低了多步实时预测中的误差。     

基于组合预测方法的风电场短期风速预测

基于持续法、人工神经网络法(ANN)和支持向量机(SVM)3种不同预测模型对内蒙古某风电场短期风速进行了预测研究,比较了不同单一预测模型的预测精度,并进行了4种不同预测模型的组合预测。计算结果表明,单一预测模型中支持向量机方法精度最高,而组合预测中3种方法组合的预测精度最高,并且组合预测精度均高于单一预测方法的精度。同时发现,当单一模型预测误差之间存在较强的负相关关系时,组合预测精度提高明显;而当单一模型预测误差之间存在较强的正相关关系时,则组合预测精度改进有限。     

A novel application of artificial neural network for wind speed estimation

Providing accurate multi-steps wind speed estimation models has increasing significance, because of the important technical and economic impacts of wind speed on power grid security and environment benefits. In this study, the combined strategies for wind speed forecasting are proposed based on an intelligent data processing system using artificial neural network (ANN). Generalized regression neural network and Elman neural network are employed to form two hybrid models. The approach employs one of ANN to model the samples achieving data denoising and assimilation and apply the other to predict wind speed using the pre-processed samples. The proposed method is demonstrated in terms of the predicting improvements of the hybrid models compared with single ANN and the typical forecasting method. To give sufficient cases for the study, four observation sites with monthly average wind speed of four given years in Western China were used to test the models. Multiple evaluation methods demonstrated that the proposed method provides a promising alternative technique in monthly average wind speed estimation.     

基于PAM-SSD-LSTM的短期风速预测

为提高短期风速预测的准确性,提出一种基于PAM聚类、奇异谱分解（SSD）和LSTM神经网络的组合预测模型来预测短期风速,以解决上述问题。首先,为提高神经网络的学习效率,采用PAM算法对原始风速数据进行相似日聚类;其次,SSD具有抑制模态混叠和虚假分量产生的优点,使用SSD分解风速序列,提取多尺度规律;最后,由于LSTM神经网络捕捉长时间依赖的序列的波动规律的能力较强,使用LSTM神经网络对分解后的风速分量进行预测,将各分量预测值叠加得到最终预测结果。实验结果表明,基于PAM-SSD-LSTM的组合预测模型可有效提高风速短期预测的准确率。     

An exergetically-sustainable operational condition of a photo-biohydrogen production system optimized using conventional and innovative fuzzy techniques

The aim of the present study was to perform an exergy-based multi-objective fuzzy optimization of a continuous photobioreactor applied for biohydrogen production from syngas via the water-gas shift reaction by Rhodospirillum rubrum. For this purpose, the conventional and innovative fuzzy optimization techniques coupled with multilayer perceptron (MLP) neural model to optimize the main exergetic performance parameters of the photobioreactor. The MLP neural model was applied to correlate three dependent variables (rational and process exergy efficiencies and normalized exergy destruction) with two independent variables (syngas flow rate and agitation speed). The developed MLP model was then interfaced with three different multi-objective fuzzy optimization systems with independent, interdependent, and locally modified interdependent objectives. The optimization process was aimed at maximizing the rational exergy and process efficiencies, while minimizing the normalized exergy destruction, simultaneously. Generally, the innovative locally modified interdependent objectives fuzzy system showed a better optimization capabilities compared with the other two fuzzy systems. Accordingly, the optimal syngas photo-fermentation for biohydrogen production in the continuous bioreactor corresponded to the agitation speed of 383.34 rpm and syngas flow rate of 13.35 mL/min in order to achieve the normalized exergy destruction of 1.56, rational exergy efficiency of 85.65%, and process exergy efficiency of 21.66%.     

基于LS-SVM的制冷系统故障诊断

为了提高制冷系统故障诊断速度及准确性,提出了基于最小二乘支持向量机(LS-SVM)的制冷系统故障诊断模型,并采用ASHRAE制冷系统故障模拟实验数据进行模型训练与验证.对一台90冷吨(约316 kW)的离心式冷水机组的7类制冷循环典型故障进行了实验.研究结果表明,LS-SVM模型对制冷系统七类故障的总体诊断正确率比支持向量机(SVM)诊断模型、误差反向传播(BP)神经网络诊断模型分别提高0.12%和1.32%;尽管对个别局部故障(冷凝器结垢、冷凝器水流量不足、制冷剂含不凝性气体)的诊断性能较SVM模型的略有下降,但对系统故障的诊断性能均有较大改善,特别是对制冷剂泄漏/不足故障;诊断耗时比SVM模型减少近一半,快速性亦有所改善.可见,LS-SVM模型在制冷系统故障诊断中具有良好的应用前景.     

Wind speed spatial estimation for energy planning in Sicily: A neural kriging application

One of the first steps for the exploitation of any energy source is necessarily represented by its estimation and mapping at the aim of identifying the most suitable areas in terms of energy potential. In the field of renewable energies this is often a very difficult task, because the energy source is in this case characterized by relevant variations over space and time. This implies that any temporal, but also spatial, estimation model has to be able to incorporate this spatial and temporal variability.The paper deals with the spatial estimation of the wind fields in Sicily (Italy) by following a data-driven approach. Starting from the results of a preliminary study, a novel technique resulting from the integration of neural and geostatistical techniques was developed in order to obtain the wind speed maps for the region at 10 and 50 meters above the ground level. The mean values of the theoretical Weibull distribution function describing the wind regime at each of the available measurement sites were used to train a multi-layer perceptron (MLP) whose goal is to compute the most of the wind spatial trends. Other pieces of information about the territory (altitude, land coverage) were also used as inputs of the network and organized into a geographic information system (GIS) environment. The remaining de-trended linear means have been computed by using a universal kriging (UK) estimator. The results of these steps were then summed up and it was thus possible to obtain a map of the estimated wind fields.     

A new strategy for predicting short-term wind speed using soft computing models

Wind power prediction is a widely used tool for the large-scale integration of intermittent wind-powered generators into power systems. Given the cubic relationship between wind speed and wind power, accurate forecasting of wind speed is imperative for the estimation of future wind power generation output. This paper presents a performance analysis of short-term wind speed prediction techniques based on soft computing models (SCMs) formulated on a backpropagation neural network (BPNN), a radial basis function neural network (RBFNN), and an adaptive neuro-fuzzy inference system (ANFIS). The forecasting performance of the SCMs is augmented by a similar days (SD) method, which considers similar historical weather information corresponding to the forecasting day in order to determine similar wind speed days for processing. The test results demonstrate that all evaluated SCMs incur some level of performance improvement with the addition of SD pre-processing. As an example, the SD+ANFIS model can provide up to 48% improvement in forecasting accuracy when compared to the individual ANFIS model alone.     

Correlation of wind speed between neighboring measuring stations

A method for establishing wind speed correlation between neighboring measuring stations is presented in this paper. The aim of this study is to develop a model, in which given the wind speed at a particular site to simulate the wind speed at another, nearby site, in order to estimate the wind power of an area. This method takes into account the evolution of the sample cross correlation function (SCCF) of wind speed in time domain and uses an artificial neural network to perform the wind speed simulation. Four separate pairs of wind data measuring stations at two different regions were examined. Tests showed that the higher the SCCF value between two sites, the better simulation achieved. Also, in a pair of stations under investigation the reference station must be the one that contains more information in its wind speed signal, in order to obtain the optimum simulation performance.     

Bayesian adaptive combination of short-term wind speed forecasts from neural network models

Short-term wind speed forecasting is of great importance for wind farm operations and the integration of wind energy into the power grid system. Adaptive and reliable methods and techniques of wind speed forecasts are urgently needed in view of the stochastic nature of wind resource varying from time to time and from site to site. This paper presents a robust two-step methodology for accurate wind speed forecasting based on Bayesian combination algorithm, and three neural network models, namely, adaptive linear element network (ADALINE), backpropagation (BP) network, and radial basis function (RBF) network. The hourly average wind speed data from two North Dakota sites are used to demonstrate the effectiveness of the proposed approach. The results indicate that, while the performances of the neural networks are not consistent in forecasting 1-h-ahead wind speed for the two sites or under different evaluation metrics, the Bayesian combination method can always provide adaptive, reliable and comparatively accurate forecast results. The proposed methodology provides a unified approach to tackle the challenging model selection issue in wind speed forecasting.     

基于人工神经网络模型的风速预测

利用在达坂城风电场30m轮毂高处的1min实测风速数据,采用人工神经网络模型ANN对未来短时间风速进行预报。通过对风速反复训练与检测来选择一组合适的模型参数,并对模型进行了误差分析。研究结果表明,使用BP神经网络对未来风速进行短时间预测能够达到较好的效果,误差较ARMA模型更精确,但是对于突变信息的处理能力仍然有限。     

Hybridizing the fifth generation mesoscale model with artificial neural networks for short-term wind speed prediction

This paper presents the hybridization of the fifth generation mesoscale model (MM5) with neural networks in order to tackle a problem of short-term wind speed prediction. The mean hourly wind speed forecast at wind turbines in a wind park is an important parameter used to predict the total power production of the park. Our model for short-term wind speed forecast integrates a global numerical weather prediction model and observations at different heights (using atmospheric soundings) as initial and boundary conditions for the MM5 model. Then, the outputs of this model are processed using a neural network to obtain the wind speed forecast in specific points of the wind park. In the experiments carried out, we present some results of wind speed forecasting in a wind park located at the south-east of Spain. The results are encouraging, and show that our hybrid MM5-neural network approach is able to obtain good short-term predictions of wind speed at specific points.     

基于邻近测风塔的风电场长期风速估算

分别采用线性相关方法、物理方法和支持向量机(SVM)方法对内蒙古不同地形的两个风电场进行了基于邻近测风塔2个月学习数据的10个月平均风速估算研究,给出了较详细的实现过程,并比较了3种估算方法的预测精度。计算结果表明,线性相关方法能快速给出预测结果,但要求两塔之间的空间相关性良好;物理方法对较平坦地形估算结果精度较高,但对于较复杂地形估算结果平均百分比误差高达15%;SVM方法能给出精度较高的估算结果,在两个风电场的估算平均百分比误差均小于5%,对复杂地形适应性强,综合结果好于其他两种方法。     

基于MMAS BP算法的短期风速非线性组合预测模型

为提高风电场短期风速的预测精度,引入一种基于改进蚁群算法优化神经网络的非线性组合预测方法,按误差平方和最小原则对所建灰色GM(1,1)模型、BP网络和RBF网络三种单一预测数据进行非线性组合,并将其结果作为最终预测值。仿真结果表明,该方法的平均绝对误差及均方误差分别为17.76%和3.68%,均小于单一模型、线性组合模型及神经网络组合模型的预测结果,提高了网络的泛化能力,降低了预测风险,为风电场风速预测提供了一种新途径。     

基于Elman神经网络的短期风电功率预测

为提高风电场输出功率预测精度,提出一种动态基于神经网络的功率预测方法。根据实际运行的风电场相关风速、相关风向和风电功率的历史数据,建立了基于Elman神经元网络的短期风电功率预测模型。运用多层Elman神经网络模型对西北某风电场实际1h和24h的风电输出功率预测,与BP神经网络模型对比,经仿真分析证明前者具有预测精度高的特点,三隐含层Elman神经网络模型预测效果最佳。这表明利用Elman回归神经网络建模对风电功率进行预测是可行的,能有效提高功率预测精度。     

Using neural networks to estimate wind turbine power generation

This paper uses data collected at Central and South West Services Fort Davis wind farm (USA) to develop a neural network based prediction of power produced by each turbine. The power generated by electric wind turbines changes rapidly because of the continuous fluctuation of wind speed and direction. It is important for the power industry to have the capability to perform this prediction for diagnostic purposes-lower-than-expected wind power may be an early indicator of a need for maintenance. In this paper, characteristics of wind power generation are first evaluated in order to establish the relative importance for the neural network. A four input neural network is developed and its performance is shown to be superior to the single parameter traditional model approach     

Wind speed forecasting based on the hybrid ensemble empirical mode decomposition and GA-BP neural network method

Wind speed is the major factor that affects the wind generation, and in turn the forecasting accuracy of wind speed is the key to wind power prediction. In this paper, a wind speed forecasting method based on improved empirical mode decomposition (EMD) and GA-BP neural network is proposed. EMD has been applied extensively for analyzing nonlinear stochastic signals. Ensemble empirical mode decomposition (EEMD) is an improved method of EMD, which can effectively handle the mode-mixing problem and decompose the original data into more stationary signals with different frequencies. Each signal is taken as an input data to the GA-BP neural network model. The final forecasted wind speed data is obtained by aggregating the predicted data of individual signals. Cases study of a wind farm in Inner Mongolia, China, shows that the proposed hybrid method is much more accurate than the traditional GA-BP forecasting approach and GA-BP with EMD and wavelet neural network method. By the sensitivity analysis of parameters, it can be seen that appropriate settings on parameters can improve the forecasting result. The simulation with MATLAB shows that the proposed method can improve the forecasting accuracy and computational efficiency, which make it suitable for on-line ultra-short term (10 min) and short term (1 h) wind speed forecasting.