Research Platform: Decentralized Energy System for Sector Coupling

Industrial facilities usually need multiple energy subsystems, e.g., for heat, cold, and electric power supply. Normally, these energy subsystems are controlled locally and independent of each other. Coupling of the different subsystems can open up additional potential. Fraunhofer IISB has developed a demonstration and research platform for investigating the benefits of such sector coupling. A major precondition is to understand the energy flows in the system and establish an overall and flexible system control to realize the required algorithms for setting up an intelligent decentralized energy system. Major components of the overall system are various storages, which extend the degree of freedom for sector coupling and increase the effectiveness of the different subsystems.     

Optimal load rating-based inspection planning of corroded steel girders using Markov decision process

Steel girder bridges are vulnerable to corrosion. To maintain their safety above a predefined target level, the load rating can be computed from the inspection results and guide the following maintenance actions. Optimizing inspection and maintenance based on load ratings has substantial practical and economic relevance. Load rating-based strategies can be categorized based on whether the inspection interval and replacement criteria are fixed or flexible. Existing studies focus on fixed inspection intervals throughout the service life. In general, their results are not optimal for inspection planning. To reduce life-cycle cost, aged steel girders may be inspected and repaired in an adaptive manner. To this end, a method based on Markov decision process (MDP) is proposed to compare the life-cycle cost of four load rating-based policies (i.e. uniform or adaptive non-uniform inspection interval, and fixed or adaptive replacement threshold). Load rating-based inspection planning is formulated as MDP and the optimal plans are obtained using dynamic programming. The conventional approach to discretize states cannot accurately approximate the non-stationary deterioration process, while state augmentation is successful in doing this but will increase computational cost. A comparison of two approaches is made to investigate their effects on life-cycle cost. A bridge girder under corrosion attack is used as an illustrative example. The results show that the load rating-based plan with an adaptive non-uniform inspection interval and fixed replacement threshold obtained using the state augmentation technique can be near-optimal.     

Automated prediction system of household energy consumption in cities using web crawler and optimized artificial intelligence

The supply of electrical energy is critical to convenient and comfortable living. However, people consume a large amount of energy, contributing to an energy crisis and global warming, and damaging some ecological cycles. Residential electricity consumption has greater elasticity than industrial and business consumption; it therefore has high energy-saving potential. This work establishes an automated platform, which provides information about residential electricity consumption in each city in Taiwan. Machine learning was used to forecast future residential electricity demand. A nature-inspired optimization method was applied to enhance the accuracy of the best machine learner, yielding an even better hybrid ensemble model. Performance measures indicate that the resulting model is accurate and provides effective information for reference. An automatic web-based system based on the model was combined with a web crawler and scheduled to run automatically to provide information on monthly residential electricity consumption in each county and city. By providing energy consumption information across the country, power providers and government can discuss policy and set different goals for energy use. The results of this study can facilitate the early implementation of energy-saving and carbon emission-reducing in cities and aid utility companies in establishing energy conservation guidelines.     

Selection of features from power theories to compose NILM datasets

The load disaggregation concept is gaining attention due to the increasing need for optimized energy utilization and detailed characterization of electricity consumption profiles, especially through Nonintrusive Load Monitoring (NILM) approaches. This occurs since knowledge about individualized consumption per appliance allows to create strategies striving for energy savings, improvement of energy efficiency, and creating energy awareness to consumers. Moreover, by using feature extraction to devise energy disaggregation, one can achieve accurate identification of electric appliances. However, even though several literature works propose distinct features to be utilized, no consensus exists in the literature about the most appropriate set of features that ensure high accuracy on load disaggregation. Thus, beyond presenting a critical analysis of some significant features often selected in the literature, this paper proposes identifying the most relevant ones considering collinearity and machine learning algorithms. The results show that high-performance metrics can be achieved with fewer features than usually adopted in the literature. Moreover, it is demonstrated that the Conservative Power Theory can offer the most representative features for appliance identification, leading to efficient power consumption disaggregation.     

Simulation based neuro-fuzzy hybrid intelligent PI control approach in four-area load frequency control of interconnected power system

This paper presents a novel control approach of hybrid neuro-fuzzy (HNF) for load frequency control (LFC) of four-area power system. The advantage of this controller is that it can handle the non-linearities, and at the same time it is faster than other existing controllers. The effectiveness of proposed controller in increasing the damping of local and inter area modes of oscillation is demonstrated in four area interconnected power system. Area-1 and area-2 consist of thermal reheat power plant whereas area-3 and area-4 consist of hydro power plant. Performance evaluation is carried out by using fuzzy, ANN, ANFIS and conventional PI and PID control approaches. The performances of the controllers are simulated using MATLAB/Simulink package. The result shows that intelligent HNF controller is having improved dynamic response and at the same time faster than ANN, fuzzy and conventional PI and PID controllers.     

How to Adapt a Lab-Scale Freeze Dryer for Assessing Dehydrating Curves at Different Heating Conditions

A laboratory-scale freeze dryer was adapted to allow control of the heat supply and on-line monitoring of sample weight during drying under vacuum condition. Several tests were carried out to verify the reliability of the developed system. The system was also tested with 10-mm-thick banana slices, obtaining the fruit drying rate, at different sample holder plate temperatures including 20 and 30°C as well as an unheated plate. The system presented in this work represents a low-cost, flexible, and easy-to-assemble piece of equipment that allows the study and optimization of the freeze drying of foods.     

微孔节流气体静压止推轴承跨缝过程时变特性研究

目前,大型气浮平台均采用花岗岩平台拼接而成,平台拼缝会对实验效果产生一定影响。针对上述问题,以微孔节流气体静压轴承运动中经过平台拼缝时的时变特性为研究对象,建立微孔节流止推轴承物理模型,并使用CFD软件与UDF相结合的动网格技术实现轴承跨越平台拼缝的动态过程仿真,研究不同气膜厚度、进气口压力、平台拼缝位置对轴承承载力和压力分布的影响。结果表明：当平台拼缝到达微孔分布圆附近时承载力急速下降,且平台拼缝到达轴承中心时承载力下降到最小值;随着气膜厚度的增加,轴承承载力的最大损失比例随之增加,并最终稳定到0.6;平台拼缝位于供气孔分布圆之外时,轴承边缘与平台拼缝之间的承载面将失效;通过增加进气口压力,轴承承载力整体有明显提升,但承载力损失速度也明显加快。     

基于NMPC-PID的大型风力机独立变桨控制

大型风力机的不平衡载荷会使叶片断裂,造成事故从而减短其使用寿命。针对大型风力发电系统在高风速区的不平衡载荷问题,提出一种NMPC-PID的独立变桨载荷控制方法。非线性模型预测控制(NMPC)用于及时调整风机桨叶的桨距角,PID控制则用于消除塔架振动的影响。运用机制方法在仿真平台搭建风力发电系统模型,运用所提控制策略进行仿真实验,并在两种情况下与模型预测控制方法(MPC)进行对比,验证了所提控制策略的可行性与有效性。     

S-877催化剂在抚顺石化EO/EG装置应用分析及优化调整

在乙烯氧化生成环氧乙烷的反应中,因原料供应和销售等问题,导致装置频繁调整负荷,再加上非计划停工以及在线仪表和离线分析不能准确的测定出系统中的氯含量,造成系统中氯含量大幅波动,通过对银催化剂S877长时间运行的数据进行分析,找出规律,优化EDC的加入量,保证催化剂选择性最优,同时确保了装置平稳优化运行。     

关于桩基承载力确定的反思与选型的简化计算

本文着重论述单桩承载力确定的正确途径。提出几种有代表性桩型的单桩承载力的建议值。并在上述认识的基础上提供一种桩型比较经济的简化计算方法。