Design and analysis of an aging‐aware energy management system for islanded grids using mixed‐integer quadratic programming

The rapid increase of renewable energy sources made coordinated control of the distributed and intermittent generation units a more demanded task. Matching demand and supply is particularly challenging in islanded microgrids. In this study, we have demonstrated a mixed‐integer quadratic programming (MIQP) method to achieve efficient use of sources within an islanded microgrid. A unique objective function involving fuel consumption of diesel generator, degradation in a lithium‐ion battery energy storage system, carbon emissions, load shifting, and curtailment of the renewable sources is constructed, and an optimal operating point is pursued using the MIQP approach. A systematic and extensive methodology for building the objective function is given in a sequential and explicit manner with an emphasis on a novel model‐based battery aging formulation. Performance of the designed system and a sensitivity analysis of resulting battery dispatch, diesel generator usage, and storage aging against a range of optimization parameters are presented by considering real‐world specifications of the Semakau Island, an island in the vicinity of Singapore.     

获各琦铜矿利用采空区及废旧巷道预热冬季入风流的研究

获各琦铜矿利用地温预热的原理,设计了冬季井筒防冻通风系统。该预热系统经过一年多的运行,采空区及废旧巷道可使约63m^3/s的冷空气由-26℃预热到+2℃以上,有效地降低了冬季期间进风井的预热压力及预热成本,节省了大量能源消耗。在实践上证明了利用采空区及废旧巷道预热冬季入风流在技术上的有效性、经济上的合理性和安全上的可靠性。     

An autothermal reforming system for diesel and jet fuel with quick start-up capability

A quick, low energy consuming and reliable start-up is essential for fuel cell systems utilizing diesel and jet fuel. A compact fuel processor for coupling with a high-temperature polymer electrolyte fuel cell is developed with electrically-heated reactors in the 28 kW_th power class. Based on this set-up, start-up strategies are developed and validated. With the basic strategy, 14 min are required in the best case to commence reforming and achieve self-sustaining operation with desired CO concentration at full load using NExBTL diesel and, respectively, 16 min using Jet A-1. However, using premium diesel, the basic strategy leads to a strong increase in the concentrations of ethane and benzene. An advanced strategy enables 16 min start time with premium diesel suppressing these undesired side products. This result is within the 30 min start-up time target for auxiliary power units for 2020 and offers a reliable option for real world applications.     

Analysis of indoor particles and gases and their evolution with natural ventilation

The air composition and reactivity from outdoor and indoor mixing field campaign was conducted to investigate the impacts of natural ventilation (ie, window opening and closing) on indoor air quality. In this study, a thermal desorption aerosol gas chromatograph (TAG) obtained measurements of indoor particle‐ and gas‐phase semi‐ and intermediately volatile organic compounds both inside and outside a single‐family test home. Together with measurements from a suite of instruments, we use TAG data to evaluate changes in indoor particles and gases at three natural ventilation periods. Positive matrix factorization was performed on TAG and adsorbent tube data to explore five distinct chemical and physical processes occurring in the indoor environment. Outdoor‐to‐indoor transport is observed for sulfate, isoprene epoxydiols, polycyclic aromatic hydrocarbons, and heavy alkanes. Dilution of indoor species is observed for volatile, non‐reactive species including methylcyclohexane and decamethylcyclopentasiloxane. Window opening drives enhanced emissions of semi‐ and intermediately volatile species including TXIB, DEET, diethyl phthalate, and carvone from indoor surfaces. Formation via enhanced oxidation was observed for nonanal and 2‐decanone when outdoor oxidants entered the home. Finally, oxidative depletion of gas‐phase terpenes (eg, limonene and α‐pinene) was anticipated but not observed due to limited measurement resolution and dynamically changing conditions.     

Intelligent coordinated controller design for a 600 MW supercritical boiler unit based on expanded-structure neural network inverse models

Under present widespread automatic generation control (AGC) centered on regional power grid, a large-capacity coal-fired supercritical (SC) power unit often operates under wide-range variable load conditions. Since a SC once-through boiler unit is represented by a typical multivariable system with large inertia and non-linear, slow time-variant and time-delay characteristics, it often makes the coordinated control quality deteriorate under wide-range loading conditions, and thus influences the unit load response speed and leads to heavy fluctuation of the main steam pressure. To improve the SC unit’s coordinated control quality with advanced intelligent control strategy, the neural-network (NN) based expanded-structure inverse system models of a 600 MW SC boiler unit were investigated. A feedforward neural network with time-delayed inputs and time-delayed output feedbacks was adopted to establish the inverse models for the load and the main steam pressure characteristics. Based on the model, a neural network inverse coordinated control scheme was designed and tested in a full-scope power plant simulator of the given SC power unit, which showed that the proposed coordinated control scheme can achieve better control results compared to the original PID coordinated control.     

可控硅整流机组的调试经验

阐述了甘肃金川集团有限公司动力厂可控硅整流机组的调试经过,总结了调试准备工作、轻载试验、重载试验及重载设备制作经验,并进行了水电阻的计算.     

重轨热锯机变速技术应用

介绍了鞍钢股份有限公司大型厂热锯机为满足产品多样化需要,实现热锯机变速功能的软硬件配置情况,着重介绍了各种变速方案具体设计思想及优缺点以及最终实施的方案。通过介绍PLC内程序的编写和SIEMENS数控器的设置,详细阐述了变速技术的实现原理。     

石油化工装置安全设计讨论——Ⅰ.工艺安全设计

工艺设计的初始阶段应综合考察工艺技术的内在安全性,工艺技术发展与技术进步,不仅要改善产品质量、提高收率、降低消耗,同时要提高装置的内在安全性。工艺路线选择上应优先采用低危险性原材料,危险物料的用量和存藏量最小化,过程条件相对缓和,不产生或少产生有害废料。装置运行的安全性还取决于装置硬件设施的可靠性和工艺条件下由介质特性、操作参数、控制技术、操作和管理水平等构成的动态系统及其平衡条件。装置生产在原料预处理、化学反应、精制分离过程中,物料性质和状态的变化和转换无不受到过程参数和系统能量平衡的影响,参数的偏离和能量的失衡都可能导致危险情况出现。     

Optimal allocation of phasor measurement unit for full observability of the connected power network

This paper presents binary particle swarm optimization (BPSO) technique for the optimal allocation of phasor measurement units (PMUs) for the entire observability of connected power network. Phasor measurement units are considered as one of the most important measuring devices in the prospect of connected power network. PMUs function may be incorporated to the wide-area connected power networks for monitoring and controlling purposes. The optimal PMU placement (OPP) problem provides reference to the assurance of the minimal number of PMUs and their analogous locations for observability of the entire connected power networks. Binary particle swarm optimization (BPSO) algorithm is developed for the solution of OPP problem. The efficacy and robustness of the proposed method has been tested on the IEEE 14-bus, IEEE 30-bus, New England 39-bus, IEEE 57-bus, IEEE 118-bus and Northern Regional Power Grid (NRPG) 246-bus test system. The results obtained by proposed approach are compared with other standard methods and it is observed that this BPSO based placement of phasor measurement units is found to be the best among all other techniques discussed.     

Stress corrosion cracking in 316L stainless steel bellows of a pressure safety valve

There were three consecutive occurrences of bellows failure in a particular pressure safety valve (PSV) of a petroleum refinery within a time span of one week. The bellows were made of 316L grade austenitic stainless steel, and the PSV was mounted on one of the vessels of vacuum gas oil service in a hydrocracker unit. Metallurgical analysis of the failed bellows revealed that the failure had occurred by stress corrosion cracking (SCC). It was found that the SCC was promoted in the bellows due to the presence of high amount of chloride ions in the operating environment. Studies confirmed that SCC had initiated from the outer surface of the bellows and propagated inwards, resulting in leakage of hydrocarbon from the PSV. The source of chlorine in the environment was identified. It was discovered that SCC in the bellows was caused due to a previous failure in the heavy polynuclear aromatics (HPNA) absorption bed located upstream the process flow line. This failure was due to the presence of high concentrations of chlorine in the granulated activated carbon that was used in the HPNA absorption bed. During the repair of the HPNA bed, there was deposition of carbon soot on the body of the PSV. This carbon soot was the source of chloride ions for SCC to occur in the bellows. Generally, in chloride SCC, crack propagation in 316L SS takes place by transgranular mode. In the present case, however, the crack propagation was predominantly by intergranular mode. The metallurgical factors responsible for this change in micro-mechanism of crack propagation during SCC have been discussed.