Optimal scheduling of thermal generating units

Scheduling the operation of thermal generating units involves the selection of units to be placed in operation and the allocation of the load among them- These two decisions must be taken so as to minimize the sum of tile startup, banking, and expected riming costs subject to the demand, spinning-reserve, and minimum down-time and up-time constraints and, sometimes, to the following two additional limitations: a unit should not be started up more than once a day; and no more than two units of the same plant should be started up simultaneously. This optimization problem is formulated in this paper as a mixed-integer nonlinear programming problem. Then, by following the Bender's approach, the problem is partitioned into a nonlinear and a pure-integer nonlinear programming problem- The First problem, which represents the economic dispatch problem, is not solved here. The second problem, usually called the unit commitment problem, is solved by a variational method and a branch-and-bound algorithm. Numerical results obtained for a network of ten generating units are presented.     

Optimal operation of a continuous DTB crystallizer

The optimal operation of a continuous crystallizer is studied by taking a real industrial scale crystallizer as an example. The objective function to be maximized is the production rate of the crystals which are larger than a certain size. Since continuous crystallizers exhibit sustained oscillation, it is important to find the optimal operation under oscillatory condition. In this study, the optimal operating condition is derived for two types of operation: one is the case where the manipulated variables are kept constant (constant input operation), and the other is the case where the values of manipulated variables are changed periodically (time varying input operation). The optimization result of time varying input operation indicates that the production rate of large crystals can be increased if the number of fine crystals in the vessel is reduced by withdrawing along with the product. Furthermore, this study examines the optimal operation of the crystallizer in the case where the sustained oscillation is eliminated by a stabilizing controller. The optimization result clearly indicates that the production rate of large crystals can be significantly increased if the operation is optimized under the condition where crystal size distribution (CSD) is stabilized.     

Optimal operation of alternating activated sludge processes

The paper presents a dynamic optimisation study of a small size single basin wastewater treatment plant. The objective is to determine optimal sequences of aeration/non-aeration times so that for a typical diurnal pattern of disturbances, the effluent constraints are respected, the plant remains in the cyclic steady-state, and the energy consumption is minimised.Based on the results of optimal state trajectories, two simple feedback rules are proposed. The simulation results obtained with these rules show very satisfactory control performances.     

Optimal operation of Petlyuk distillation: steady-state behavior

The “Petlyuk” or “dividing-wall” or “fully thermally coupled” distillation column is an interesting alternative to the conventional cascaded binary columns for separation of multi-component mixtures. However, the industrial use has been limited, and difficulties in operation have been reported as one reason. With three product compositions controlled, the system has two degrees of freedom left for on-line optimization. We show that the steady-state optimal solution surface is quite narrow, and depends strongly on disturbances and design parameters. Thus it seems difficult to achieve the potential energy savings compared to conventional approaches without a good control strategy. We discuss candidate variables which may be used as feedback variables in order to keep the column operation close to optimal in a “self-optimizing” control scheme.     

Optimal design and operation of a wastewater purification system

Due to the importance of coastal areas, is of the highest interest to implement purification systems that with minimum cost are able to assure water quality standards in agreement with the regional legislations. This work addresses the optimal design (outfall locations) and optimal operation (level of oxygen discharges) of a wastewater treatment system. This problem can be mathematically formulated as a two-objective mixed design and optimal control problem with constraints on the states and the design and control variables.     

多台冷水机组联合运行优化控制策略

冷水机组通常占建筑物系统总能耗的主要部分,因此冷水机组运行数量控制在实现空调系统节能方面起着重要作用。针对多台冷水机组联合运行时台数选择和负荷分配不合理的问题,文章将通过TRNSYS模拟得出的负荷值聚类分析,确定不同负荷值对应的冷水机组运行台数,并提出一种冷水机组排序优化控制方法改善顺序控制方式以实现其合理运行与节能。以某大型办公建筑为例,将优化控制前后冷水机组运行的进行总能耗对比。实验结果表明:与顺序控制相比,冷水机组优化控制后两个工作日总能耗分别节约126.1kW和342.5 kW,节能率分别为4.15%和5.22%。通过利用冷水机组顺序优化控制可满足建筑的冷负荷需求同时实现降低系统能耗,在空调系统节能方面具有工程实际应用价值。     

Optimal operation of batch reactors—a personal view

This paper presents a personal, thus necessarily subjective, view of the operation of batch and semi-batch reactors. The emphasis is on safety, product quality and scale-up. Key characteristics of discontinuous reaction systems are discussed, along with the resulting implications for monitoring, control and optimization. The industrial needs are compared with the research solutions proposed by academia. It is argued that, in industry, measurement and modeling issues are often more important than the algorithmic aspects related to the computation of control and optimization strategies. Major challenges and selected research opportunities are discussed.     

Optimal design of thermal loaded composites filled with curvilinear fibers

The problem of optimal design of shape and orientation of fibers in composite material, leading to the local inhomogeneity of its parameters, is considered in this paper. The paper concerns the problem of curvilinear fibers arrangement in the composite material, so that the structural element made from this material can fulfill the requirements imposed on its thermal properties. An equivalent homogeneous orthotropic model of the composite is utilized for this purpose and next, basing on this model, the attempt is taken to determine the most profitable orientation and arrangement of fibers in the layers of the composite in order to obtain the desired behavior of structure. To solve this problem, the optimization method based on evolutionary algorithm is applied, and it is supplemented with finite element method for heat transfer analysis.     

Optimal control of rapid thermal annealing in a semiconductor process

This study focuses on the optimal control of rapid thermal annealing (RTA) used in the formation of ultrashallow junctions needed in next-generation microelectronic devices. Comparison of different parameterizations of the optimal trajectories shows that linear profiles give the best combination of minimizing junction depth and sheet resistance. Worst-case robustness analysis of the optimal control trajectory motivates improvements in feedback control implementations for these processes. This is the first time that the effects of model uncertainties and control implementation inaccuracies are rigorously quantified for RTA.     

Optimal operation of oil and gas production using simple feedback control structures

The purpose of this paper is to describe the control challenges related to optimal operation of oil and gas production wells, and show that optimal operation can be achieved using simple feedback control structures. In particular, we find that conventional feedback control structures can efficiently handle changes in active constraint regions using simple logics such as split-range and selectors. This eliminates the need for complex models to be used in the optimization problem, and in addition eliminates the need to solve numerical optimization problems online. Thus, by using only simple feedback controllers that have been used widely in the oil and gas industry, it has a higher chance of implementation. We demonstrate the use of simple feedback controllers on two application examples; 1) a gas-lift optimization simulation study with a network of six gas-lifted wells, 2) an experimental study of optimal control of electrical submersible pump (ESP) lifted oil wells tested on a large-scale experimental test facility with a full scale ESP and live viscous crude oil.     

动态规划-粒子群算法在水库优化调度中的应用

水库优化调度是一个典型的具有多约束条件的、动态的、非线性的优化问题。针对这些问题,利用动态规划-粒子群(DP-PSO)算法加以求解。利用动态规划中的多阶段最优策略原理,将水库优化调度问题转化为多阶段决策子问题,各个子问题采用粒子群算法优化求解。数值实验表明,在计算时段较多时,DP-PSO算法计算的可靠性明显优于一般的动态规划(DP)算法,在计算时间上,DP-PSO算法用时较动态规划-遗传算法(DP-GA)少。     

基于等间隔运行模式的群组电梯系统优化调度方法

针对群组电梯系统运行调度优化问题,本文采用多目标优化模型,基于电梯群组等间隔运行模式的操作规则,建立一类以乘客平均候梯时间最短为主要目标的群组优化策略.通过分析群组电梯系统运行中乘客候梯时间、服务时间、轿厢拥挤度和电梯能耗等指标,建立电梯系统运行的动态指标评价模型,考虑电梯客流的随机性因素,提出乘客候梯等间隔派梯规则和算法,实现了电梯系统多目标优化的动态调度方法.实验结果表明,对比传统的最短距离调度算法,本文方法可以降低乘客平均候梯时间13.1%,提高群组电梯系统工作性能.     

Optimal control of combined heat and power units under varying thermal loads

This paper describes a model based optimizer that allows a combined heat and power (CHP) unit to supply backup power to a Smart Grid on the one hand and minimize the cost for heat and power supply on the other hand. The model of the CHP unit is lean but nevertheless accurately represents the unit behavior, including thermal behavior of the storage as well as the aging effect of engine starts. Thanks to the small model dimension we can solve the optimal dispatch problem efficiently using dynamic programming. Two selected soft- and hard-ware in the loop tests are discussed to demonstrate the performance of the approach. A re-optimization strategy is discussed that allows reactions to wrong predictions of external influences like weather.     

Optimal annular plates with respect to their stability under thermal loadings

In the paper the uni- and multimodal optimization problems of elastic annular plates with respect to their stability under thermal loading are investigated. We look for such a distribution of a thickness of a plate (circularly symmetric), which leads to the maximum increment |ΔT| of temperature, causing buckling of the optimal structure under the equality constraint of a constant volume of the material and under inequality constraints imposed on the minimal and maximal values of a plate thickness. The optimal solutions for different modes of supports and different ratio of the inner and outer radius are looked for using the method of moving asymptotes and the simulated annealing.A short version of the paper was presented at WCSMO-6     

Optimal operation of transmission power networks by using improved stochastic fractal search algorithm

Neural Computing and Applications - This paper presents the application of an improved stochastic fractal search algorithm (ISFSA) for optimizing five single objectives of optimal power flow (OPF)...     

Optimal fusion aided face recognition from visible and thermal face images

Multimedia Tools and Applications - This paper proposes a novel Eigen face recognition that is aided by fusion of visible and thermal face images to improve the face recognition accuracy. We adopt...     

参数运算回路在火电厂炉膛压力调节系统中的应用

在研究国内外火电厂自动化技术发展的基础上,分析了我国火电厂锅炉炉膛压力调节系统的现状,提出了参数运算回路的开发思想,并结合工程应用经验,描绘了其在火电厂控制系统中的应用前景。     

基于分布参数控制理论的可变质产品最优经营策略

应用分布参数控制理论,研究了零售企业对于可变质产品的最优经营管理问题.通过建立可变质产品的最优经营管理的分布参数控制系统模型,得出了零售企业每个瞬间每种可变质产品的最优经营管理策略,并对空间伴随函数和控制变量给出了明确的经济学解释.该模型更合理地描述了可变质产品的实际经营特性,具有一定的现实意义和实用价值.     

Optimal harvesting strategies for a multi-cycle and multi-pond shrimp operation: A practical network model

In this paper, we introduce a network formulation of the optimal scheduling model for a multi-cycle and multi-pond shrimp operation grounded on the original optimal harvesting theory for a single production unit. The optimal schedule comprises the harvesting and restocking time that maximizes total profit throughout the planning horizon, bounded by the underlying biological and economic conditions. The model takes into account the information such as harvest size distribution, seasonality of price, temperature and weight-dependent growth, and labor force and market demand constraints. We applied the model to an existing shrimp operation in Hawaii with 40 one-acre ponds and generated the optimal schedule for a year that maximizes overall production. The model schedule is found to be able to increase total production by 5% when compared to the schedule generated using an “educated” trial-and-error procedure currently practiced by this operation. Further insights for this multi-cycle and multi-pond scheduling problem were also generated through several alternate simulations. It is found that labor force and market demand constraints are the key factors in scheduling multi-cycle and multi-pond shrimp operations.