核电站蒸汽发生器水位的自抗扰多模型控制方法研究

针对核电站蒸汽发生器水位控制的非线性分布特点,在自抗扰控制技术的基础上结合多模型控制提出了蒸汽发生器水位系统新的控制方案.在该控制方案中,对蒸汽发生器设计了多模型控制系统,并针对各个模型分别设计了不同负荷下的自抗扰控制器,可以对扩张状态进行在线实时估计,因此设计的扰动补偿不依赖于模型便能够达到快速消去扰动的效果.将该方法用于蒸汽发生器水位控制系统进行仿真研究,结果表明：该控制方案实现了对蒸汽发生器水位良好的动态控制,具有较强的鲁棒性和抗干扰能力,且算法简单,便于调试.     

核蒸汽轮机系统数模混合实时仿真

本文建立了核动力装置蒸汽轮机系统的数学模型和数模混合实时仿真模型,考虑了汽水分离器ＭＳ容积惯和热惯性对系统的影响,     

基于遗传算法的核电站蒸发器高阶水位模型的降阶方法

针对核电站蒸汽发生器的高阶水位输出模型,提出了次最优降阶算法与遗传算法相结合的模型降阶方法.利用该方法对典型负荷下的核电站蒸发器水位系统模型进行了降阶,并在Matlab平台上对降阶后的模型进行了仿真.结果表明:采用次最优降阶算法与遗传算法相结合的降价方法得到的优化模型比传统降阶方法得到的模型更接近原始模型,利用该方法可以解决高阶线性控制系统模型优化降阶的问题.     

单元机组过热汽温控制系统的负荷适应性

为了增强过热汽温控制系统的负荷适应能力,以一个600MW机组的过热汽温系统为研究对象,设计了由4组局部控制器组成的负荷调度控制系统,并以主蒸汽流量作为系统的调度变量。每一组局部控制器对应一种典型工况,采用串级内模原理进行设计和整定,其中,高阶的外回路控制器通过Taylor级数展开的方法简化为实际PID形式。控制系统各局部控制器之间的跟踪与无扰切换通过Hanus方法实现。系统保留了传统串级控制系统克服内回路扰动、提高系统工作频率的优点。在不同负荷下的仿真试验以及大范围变工况试验均表明,该系统具有良好的负荷适应能力。图5表3参3     

某核电堆型蒸汽发生器排污系统设计改进

根据全范围事故分析结果,在发生蒸汽发生器传热管破裂(SGTR)事故中,为使发生故障的蒸汽发生器水位不会上升太快,需通过蒸汽发生器排污系统排污管线来控制故障蒸发器的水位和压力。通过对蒸汽发生器排污系统进行设计改进,提高系统的设计标准,将破损蒸汽发生器内漏液排向内置换料水箱,使破损蒸汽发生器降压,同时限制破损蒸汽发生器水位,防止破损蒸汽发生器满溢,满足蒸汽发生器排污系统在设计基准事故工况下承担安全功能的要求。改进后的蒸汽发生器排污系统满足国内三代核电技术的要求,为国内三代核电的安全性提供理论依据。     

基于混杂自动机的大型风力发电机组全程控制

风力发电系统是具有不确定性的复杂非线性系统,机组运行工况变化十分频繁。通过对风力发电机组的系统特性分析,发现风力发电系统呈现出混杂系统的典型特征。因此,基于混杂自动机理论建立了1.5 MW双馈型风电机组的混杂动态模型,并根据风力发电机组控制策略设计了能够在机组运行中实现全程自动化的混杂控制系统。仿真结果表明,基于混杂自动机的动态模型可以实现风电机组的全程模拟,所设计的混杂控制系统能够满足风电机组全程控制要求,证明了混杂系统理论应用于风力发电研究领域的有效性。     

A simplified dynamic model of building structures integrated with shaped-stabilized phase change materials

The use of phase change materials (PCM) to enhance the building energy performance has attracted increasing attention of researchers and practitioners over the last few years. Thermodynamic models of building structures using PCMs are essential for analyzing their impacts on building energy performance at different conditions and using different control strategies. There are few PCM models of detailed physics providing good accuracy in simulating thermodynamic behavior of building structures integrated with PCM layers. However, simplified models with acceptable accuracy and good reliability are preferable in many practical applications concerning computation speed and program size particularly when involving large buildings or models are used for online applications. A simplified physical dynamic model of building structures integrated with SSPCM (shaped-stabilized phase change material) is developed and validated in this study. The simplified physical model represents the wall by 3 resistances and 2 capacitances and the PCM layer by 4 resistances and 2 capacitances respectively while the key issue is the parameter identification of the model. The parameters of the simplified model are identified using genetic algorithm (GA) on the basis of the basic physical properties of the wall and PCM layer. Two GA-based preprocessors are developed to identify the optimal parameters (resistances and capacitances) of the model by frequency-domain regression and time-domain regression respectively. Validation results show that the simplified model can represent light walls and median walls integrated with SSPCM with good accuracy.     

Boiler-turbine control system design using a genetic algorithm

This paper discusses the application of a genetic algorithm to control system design for boiler-turbine plant. In particular we study the ability of the genetic algorithm to develop a proportional-integral (PI) controller and a state feedback controller for a nonlinear multi-input/multi-output (MIMO) plant model. The plant model is presented along with a discussion of the inherent difficulties in such controller development. A sketch of the genetic algorithm (GA) is presented and its strategy as a method of control system design is discussed. Results are presented for two different control systems that have been designed with the genetic algorithm     

A novel methodology for scrutiny of autonomous hybrid renewable energy system

The optimal design of a hybrid system with different configurations including renewable generation is presented in this paper. A novel multi‐objective function consisting of 6 different objectives of hybrid system is reported using GA, PSO, and TLBO to decide the optimal configurations of parameters. The technical (loss of power supply probability, renewable factor), economical (cost of energy, penalty and fuel consumption), and social (job creation, human development index, and particular matter) features are investigated as objectives simultaneously for optimal design of hybrid system. The different objective indices namely cost of energy, loss of power supply probability, particular matter, human development index, job creation, and renewable factor indices are considered. The newly invented particular matter factor for design consideration of hybrid system directly shows the human health impacts, while pollutant emission is measured in the hybrid system design. The optimum values of objective indices are decided on the basis of the minimum value of multi‐objective function. The distinct cases from I to VI of hybrid system are examined for optimal configuration including different combinations of PV, wind, biomass, diesel generator, and battery bank. The resulting analysis of each case reveals that the performance of TLBO is better than PSO, and PSO is better than GA in all respect through new multi‐objective function and found case I is more efficient solution.     

Assessment of boiler tubes overheating mechanisms during a postulated loss of feedwater accident

Due to their simplicity and passive nature, natural circulation loops have many industrial applications and being increasingly used in many innovative designs as the new generation of nuclear reactor cooling systems. Consequently, special attention is increasingly considered towards their safety issues. In the current framework, a safety aspect related to the loss of feedwater in an industrial D-type steam boiler is assessed. Indeed, loss of feedwater event occurs frequently during steam generator facilities lifetime. Under such conditions, the system integrity is in jeopardy and serious hazards and economic losses could occur. Up to now, specific numerical models have been used to simulate the thermal-hydraulic phenomena occurring under such circumstances. Such models are generally based upon simplified assumptions, and if complex model are performed, their applications are generally restricted to the facility they have been developed for. In the current framework, an attempt is made to apply a multipurpose best estimate (BE) thermal-hydraulic system code, namely, RELAP5/Mod3.2 to simulate steady-state and transient dynamic behaviors of a two-phase natural circulation steam boiler. For this purpose, two loss of feedwater scenarios, with and without the actuation of the boiler control system, have been performed. The analysis results show on one hand the achievement in applying RELAP5 for a conventional boiler system, and on the other hand the efficiency of the control systems to mitigate the accident consequences.     

基于改进型GA优化FNNC的SG水位控制系统仿真研究

蒸汽发生器水位直接影响到整个核电站的安全及稳定运行,但蒸汽发生器本身由于所具有的高度复杂性、非线性性、时变性等特性,导致传统的串级PID控制等方法难以取得好的控制效果.本研究在串级控制的基础上,采用模糊神经网络来对蒸汽发生器水位进行控制,该控制算法能够充分发挥模糊控制及神经网络的优点.另外,为了减小模糊神经网络参数初值的选择对控制器的性能影响,将一种改进型遗传算法用于模糊神经网络控制器的参数优化.仿真结果表明,设计的控制方法无论是抗干扰能力还是在鲁棒性方面与传统的串级PID控制及常规的模糊神经网络控制相比较都有了很大的提高.     

Electrical and electrical–thermal power plants with molten carbonate fuel cell/gas turbine‐integrated systems

In this article the calculation tool further developed and implemented in Matlab language by the authors was used to determine some optimal operating conditions in electrical and thermal or electrical terms for two different types of hybrid systems: molten carbonate fuel cells (MCFC)/gas turbine with their heat recovery system and the hybrid systems operating in these optimal conditions were analyzed. In the heat recovery system, in both cases, a part of the thermal energy of these gases is used to produce the steam necessary for the MCFC system. The remaining thermal energy is used, in one case, for the production of steam at various levels of pressure and temperature, which feeds a steam bottom plant to produce additional electric energy; in the other case, the same thermal energy is used to produce steam for cogenerative use. The heat recovery system was suitably designed according to the circumstances and the performances and the specific CO₂ emissions of the hybrid systems were evaluated. Copyright © 2010 John Wiley & Sons, Ltd.     

Optimization strategy for element sizing in hybrid power systems

This paper presents a procedure to evaluate the optimal element sizing of hybrid power systems. In order to generalize the problem, this work exploits the “energy hub” formulation previously presented in the literature, defining an energy hub as an interface among energy producers, consumers and the transportation infrastructure. The resulting optimization minimizes an objective function which is based on costs and efficiencies of the system elements, while taking into account the hub model, energy and power constraints and estimated operational conditions, such as energy prices, input power flow availability and output energy demand. The resulting optimal architecture also constitutes a framework for further real-time control designs.Moreover, an example of a hybrid storage system is considered. In particular, the architecture of a hybrid plant incorporating a wind generator, batteries and intermediate hydrogen storage is optimized, based on real wind data and averaged residential demands, also taking into account possible estimation errors. The hydrogen system integrates an electrolyzer, a fuel cell stack and hydrogen tanks. The resulting optimal cost of such hybrid power plant is compared with the equivalent hydrogen-only and battery-only systems, showing improvements in investment costs of almost 30% in the worst case.     

Supervisory and optimal control of central chiller plants using simplified adaptive models and genetic algorithm

This paper presents a model-based supervisory and optimal control strategy for central chiller plants to enhance their energy efficiency and control performance. The optimal strategy is formulated using simplified models of major components and the genetic algorithm (GA). The simplified models are used as the performance predictors to estimate the system energy performance and response to the changes of control settings and working conditions. Since the accuracy of the models has significant impacts on the overall prediction results, the models used are linear in the parameters and the recursive least squares (RLS) estimation technique with exponential forgetting is used to identify and update the model parameters online. That is to ensure that the linear models can provide reliable and accurate estimates when working condition changes. The GA, as a global optimization tool, is used to solve the optimization problem and search for globally optimal control settings. The performance of this strategy is tested and evaluated in a simulated virtual system representing the actual central chiller plant in a super high-rise building under various working conditions. The results showed that this strategy can save about 0.73–2.55% daily energy of the system studied, as compared to a reference strategy using conventional settings.     

一种设计模糊-PID复合控制器的新方法及其在电厂控制中的应用

为提高大型火电机组过热蒸汽温度串级控制的性能，提出了一种新型模糊-PID复合控制器的设计方法。该方法可实现在偏离工作点较远的区域模糊控制中起主要控制作用，在工作点附近则主要实施PID控制，实现了两种控制的优势互补，同时还为模糊控制器提供了一种系统化设计方法。实际工业应用结果表明：采用该方法设计的过热蒸汽温度串级控制系统比常规方法设计的系统具有更强的适应能力和良好的控制品质。图9表1参6     

Modelling of hybrid energy system—Part I: Problem formulation and model development

A well designed hybrid energy system can be cost effective, has a high reliability and can improve the quality of life in remote rural areas. The economic constraints can be met, if these systems are fundamentally well designed, use appropriate technology and make use effective dispatch control techniques. The first paper of this tri-series paper, presents the analysis and design of a mixed integer linear mathematical programming model (time series) to determine the optimal operation and cost optimization for a hybrid energy generation system consisting of a photovoltaic array, biomass (fuelwood), biogas, small/micro-hydro, a battery bank and a fossil fuel generator. The optimization is aimed at minimizing the cost function based on demand and potential constraints. Further, mathematical models of all other components of hybrid energy system are also developed. This is the generation mix of the remote rural of India; it may be applied to other rural areas also.     

Exergy based performance analysis of a solid oxide fuel cell and steam injected gas turbine hybrid power system

This paper presents exergy analysis of a hybrid solid oxide fuel cell and gas turbine (SOFC/GT) system in comparison with retrofitted system with steam injection. It is proposed to use hot gas turbine exhaust gases heat in a heat recovery steam generator to produce steam and inject it into gas turbine. Based on a steady-state model of the processes, exergy flow rates are calculated for all components and a detailed exergy analysis is performed. The components with the highest proportion of irreversibility in the hybrid systems are identified and compared. It is shown that steam injection decreases the wasted exergy from the system exhaust and boosts the exergetic efficiency by 12.11%. Also, 17.87% and 12.31% increase in exergy output and the thermal efficiency, respectively, is demonstrated. A parametric study is also performed for different values of compression pressure ratio, current density and pinch point temperature difference.     

蒸汽轴向流动对汽轮发电机组轴系扭振响应的影响

对在汽轮机高压和中压调节阀快关动作后蒸汽沿轴向流动过程对轴系扭振响应的影响进行了研究。轴系的计算模型采用连续质量模型。外激励模型是考虑了汽轮机ＤＥＨ系统、热力系统以及单机对无穷大电网的机电耦合数学模型。对３００ＭＷ汽轮发电机组的仿真计算表明,考虑蒸汽流动导致的激励扭矩沿汽轮机轴向瞬时变化时,对轴系的扰动和轴系扭振的激励加强,蒸汽载荷变化对汽轮发电机组轴系扭振的影响是较大的,在轴系安全评价中必须加以考虑。图４参３     

Study and control of the optimal generation temperature in NH3–H2O absorption refrigeration systems

This paper presents the results of a study on the optimal generator temperature (OGT) in single stage NH₃–H₂O Absorption Refrigeration Systems (AARS). It is well known that the generation temperature affects the AARS’s Coefficient of Performance (COP) and that there is a temperature value, called optimal generation temperature, for which the COP is maximum. Therefore, to develop new control strategies designed to maintain the optimal temperature in the system generator, it is necessary to study the dependency of this temperature on thermal operating conditions and system design parameters. One such type of study has been carried out here by means of a parametric analysis, using a simple model implemented in a computer program. Based on the results obtained a novel control system that works on two separated control-loops has been designed. The proposed control system maintains a constant temperature in the space to refrigerate as well as the optimal temperature in the system generator.     

超临界机组汽轮机调速系统模型参数确定的新方法

汽轮机调速系统模型参数的确定,对各种热力发电机组的仿真,控制系统的设计及电力系统动态研究具有重大意义.通过蒸汽发电机组有效热平衡数据计算出汽轮机模型参数,得出各种不同工况下参数的变化规律,比实测法更方便简捷实用.对600MW超临界机组汽轮机调速系统的模型参数进行分析计算,并用该模型针对特殊的阶跃响应作出仿真和分析.