Methods used for evaluation of actual power generating thermal cycles and comparing them

In this study, thermodynamic optimization criteria used for assessing thermal engines are investigated and compared. The Purpose of this is to determine the most advantageous criteria. An irreversible Carnot cycle is analyzed by using five different methods and results are compared. According to calculations, the ecological function criterion (ECF) is defined as the most convenient optimization method. Although, its work output is less than the maximum work criteria and maximum available work (MAW), it has advantageous in terms of entropy generation and first law efficiency. In addition, ecological coefficient of performance (ECOP) and exergetic performance criteria (EPC) values provide minimum entropy generation and maximum efficiency at their maximum, however, their work output is very small. ECF obtains its maximum values at x = 0.488 (377.175 kW) for endoreversible cycle and at x = 0.477 (329.812 kW) for irreversible cycle. For these reasons, ECF is suggested as the best optimization criteria.     

Effect of varying concentration and temperature on steady and dynamic parameters of low concentration photovoltaic energy system

Low-concentration photovoltaic (LCPV) system has huge potential for further cost reduction of solar photovoltaic (PV) power as compared to flat panel PV. The dependence of steady state and dynamic parameters on concentration and temperature is crucial to extract maximum power from solar photovoltaic system. This article aims to present the effect of varying concentration and temperature on steady state and dynamic parameters of LCPV system under actual test conditions (ATC). The rate of change in I_SC with solar irradiation i.e., dI_SC/dG is found as 0.25 A/W assuming ≈±1 °C change in module temperature. The effect of temperature on inherent material properties responsible for photo-conversion efficiency is studied using impedance spectroscopy technique. A linear response of series resistance of LCPV module is observed with respect to change in module temperature, i.e. dR_S/dT from 297 to 333 K is in the range of 1.15–1.20 Ω with a rate of 1 mΩ/K. From real-time analysis of LCPV system open-circuit voltage found decreasing from 21 to 20.6 V with temperature coefficient of voltage ≈−0.061 V/K. The dynamic resistance has a positive coefficient of module temperature i.e., dr_d/dT given by 0.49 Ω/K.     

基于瞬态热网络法的细长型永磁电机优化设计研究

本文将瞬态热网络法应用到起重机用细长型外转子永磁电机的优化设计中,以电机效率和成本为优化目标,对一台37.0kW永磁电机进行优化设计。选择永磁体厚度、气隙长度g、电机铁心轴向长度、每槽导体数、导线线规、永磁体厚度六个参数为优化变量,同时约束其槽满率、定子齿部磁密、定子轭部磁密、最大温升、最大转矩在一定范围内。本文分析了细长型永磁电机结构参数对铜损耗和效率的影响,再利用粒子群优化算法对永磁电机进行优化设计。优化结果显示:电机效率提高1.1%,成本也略有下降。最后通过有限元仿真,验证了瞬态热网络法的可行性和准确性。     

Modeling and Design Optimization Of Permanent Magnet Motors

ABSTRACT

Variable-speed permanent (PM) magnet motors are being used in an ever-increasing range of industrial and commercial applications. The objective of this paper is to provide a basis for optimizing the design of such permanent magnet motors and, through this, to provide insight into a comparison of PM motors with other types of drive motor. First, design models are presented for the approximate analysis of torque capability, losses, thermal characteristics, magnet protection and power factor control. These models are then used in an optimization program using sequential unconstrained minimization techniques to produce designs for a wide range of motor torque ratings. In order to examine the potential for large PM motor drives, the design criterion chosen for emphasis in optimization is the minimum total lifetime cost, including the cost of losses. The high efficiency and good power-to-weight ratio of the optimized PM motors leads to a total present value cost which is expected to be significantly lower than achieved with induction motors.     

Robust non-fragile power system stabilizer

This paper presents a step towards the design of robust non-fragile power system stabilizers (PSSs) for single-machine infinite-bus systems. To ensure resiliency of a robust PSS, the proposed approach presents a characterization of all stabilizers that can guarantee robust stability (RS) over wide range of operating conditions. A three-term controller (x₁ + x₂s)/(1 + x₃s) is considered to accomplish the design. Necessary and sufficient stability constraints for existing of such controller at certain operating point are derived via Routh–Hurwitz criterion. Continuous variation in the operating point is tackled by an interval plant model where RS problem is reduced to simultaneous stabilization of finite number of plants according to Kharitonov theorem. Controller triplets that can robustly stabilize vertex plants are characterized in a similar manner. The most resilient controller is computed at the center of maximum-area inscribed rectangle. Simulation results confirm robustness and resiliency of the proposed stabilizer.     

基于博弈论的电动汽车轮毂电机热源损耗优化

为降低具有高功率、高转矩密度等特点的电动汽车轮毂电机热源损耗,提出了基于博弈论的外转子式永磁同步轮毂电机的多目标优化设计方法。首先应用磁路法推导了电机各项损耗的解析表达式;其次以定子槽形的尺寸为设计变量,以定子铁耗、绕组铜耗、永磁体涡流损耗和电机效率为优化目标,建立电机优化设计数学模型;最后应用基于博弈论的多目标优化算法(Game Theory Optimization Algorithm,GTO),同时结合改进粒子群算法(Advanced Particle Swarm Optimization Algorithm,APSO)对电机定子槽型进行优化设计,并借助有限元仿真软件进行了辅助计算。研究结果表明：相较于原设计方案,优化后电机功率损耗减少32.6%,效率提高6.12%。     

Pole-zero assignment adaptive stabiliser

This paper presents a new adaptive power system stabiliser able to provide acceptable damping over a wide range of operating points. The control strategy is based on a new adaptive technique named Pole-Zero Assignment Controller (PZAC) in which a particular power system transfer function (G_d(s) = Δδ/ΔP_m) is modified to a standard form based on an explicit system identification. Controller design is mainly based on continuous-time system because of using the delta operator rather than the more usual shift operator. Simulation studies performed on a multimachine model are presented. Results clearly show the benefits of the proposed adaptive controller for stability enhancement of a power system, especially where there are large changes in operating point.     

Parameter Sensitivity Analysis for Line-Start Permanent Magnet Motors

ABSTRACT

A comprehensive study of the parameter sensitivity on both the synchronous and asynchronous performances of permanent magnet machines is presented. Based on the 2-axis theory for permanent magnet motor, performance equations are derived In terms of normalized machine parameters. Such an analysis can be used successfully in design optimization of permanent magnet machines.

A normalized power equation for evaluating the steady-state stability limits of such type of motor is also given. Simulation results obtained are confirmed with experimental results using a number of different rotor designs. Useful conclusions have been provided, which are considered to be a good aid for designing any permanent magnet motor.     

基于裂比的非晶合金永磁电机设计技术

非晶合金材料电磁性能优异,应用于电机领域能显著降低电机铁心损耗,提高电机效率。针对非晶合金材料的特点,基于永磁电机基本设计理论,推导了非晶合金电机铜耗与铁心损耗的解析表达式。基于非晶合金永磁电机损耗的解析表达式对非晶合金永磁电机裂比(定子内外径之比)、磁密比值(气隙磁密与铁心磁密之比)的设计进行了研究,得出了非晶合金永磁电机裂比、磁密比值的设计规律。在对非晶合金永磁电机设计规律研究的基础上完成了一台非晶合金永磁电机的设计并进行了试验。所做的研究对非晶合金电机的设计及优化具有一定的参考价值。     

Automatic generation control of a multi-area system using ant lion optimizer algorithm based PID plus second order derivative controller

This article presents the automatic generation control of an unequal three area thermal system. Single stage reheat turbines and generation rate constraints of 3%/min are considered in each control area. Controllers such as Integral (I), Proportional – Integral (PI), Proportional – Integral – Derivative (PID), and Proportional – Integral – Derivative Plus Second Order Derivative (PID + DD) are treated as secondary controllers separately. A nature inspired optimization technique called Ant Lion Optimizer (ALO) algorithm is used for simultaneous optimization of the controller gains. Comparison of dynamic responses of frequencies and tie line powers corresponding to ALO optimized I, PI, PID and PID + DD controller reveal the better performance of PID + DD controller in terms of lesser settling time, peak overshoots as well as reduced oscillations. Robustness of the optimum gains of best controller obtained at nominal conditions is evaluated using sensitivity analysis. Analysis exposed that the optimum PID + DD controller gains obtained at nominal are robust and not necessary to reset again for changes in loading, parameter like inertia constant (H), size and position of disturbance. Furthermore, the performance of PID + DD controller is found better as compared to PID controller against random loading pattern condition.     

永磁同步电动机电磁场的有限元分析

以一台永磁同步电动机作为分析模型,应用Ansoft公司的Maxwell 2D有限元分析软件对永磁同步电动机的电磁场进行了仿真,结果可以用来指导水磁同步电动机的优化设计。     

Thermo-economic multi-objective optimization for a solar-dish Brayton system using NSGA-II and decision making

A 100 kW regenerative Brayton heat engine driven by the hybrid of fossil fuel and solar energy was considered for optimization based on multiple criteria. A thermodynamic model of such hybrid system was developed so that the power output, thermal efficiency and dimensionless thermo-economic performance with the imperfect performance of parabolic dish solar collector, the external irreversibility of Brayton heat engine and conductive thermal bridging loss could be obtained. Evolutionary algorithm based on NSGA-II (Elitist Non-dominated Sorting Genetic Algorithm) was employed to optimize triple-objective and dual-objective functions, where the temperatures of hot reservoir, cold reservoir and working fluid, the effectiveness of hot-side heat exchanger, cold-side heat exchanger and regenerator were considered as design variables. Using decision makings, including Shannon Entropy, LINMAP and TOPSIS methods, the final optimal solutions were selected from Pareto frontier obtained by NSGA-II. The results show that there exists an appropriate working fluid temperature to cause optimal solution under each given condition. The comparisons of triple-objective and dual-objective optimization with single-objective optimization indicate that multi-objective optimization can yield the more suitable results due to the lower deviation index from the ideal solution. In the analysis of triple-objective optimization, an expected result is obtained that the optimal values of the power out, efficiency and dimensionless thermo-economic performance of solar-dish Brayton system (68.65 kW, 0.2331 and 0.3077) are 22.6%, 34.9% and 18.4% respectively less than that of convectional Brayton heat engine. Finally, a range of functional relationship between the optimized objectives in Pareto frontier is fitted to provide more detailed insight into the optimal design of solar-dish Brayton system.     

磁悬浮人工心脏驱动电机的优化设计

提出了基于电磁场有限元分析技术,对磁悬浮人工心脏的驱动电机进行优化设计的方法。根据对人工脏器的设计要求,设计了一台单面轴隙式永磁无刷直流电机作为人工心脏的驱动电机。通过建立驱动电机的3D整体模型,研究电机气隙中的磁场分布。同时结合电机损耗的计算方法,以提高电机的总体效率、降低电机的整体尺寸为目标,对驱动电机的电机线圈、永磁体阵列的尺寸进行优化设计。仿真与计算得出的优化设计结果,可以为人工心脏的工程设计提供参考。     

Permanent Magnet DC Motors Design Criteria and Operation Advantages

Permanent magnet dc motors have found many successful applications in industry. In particular, the machine tool industry utilizes the major share of all the permanent magnet motors produced. These motors typically exhibit greater stability of operation, linearity, higher maximum speeds, straightforward design, and higher efficiency. The applications to which these motors are addressed, however, impose fairly sophisticated design choices to maintain high performance along with optimization of unit design. In trying to optimize motor design without loss of performance, the selection of magnet material has the greatest impact upon eventual motor performance, size, and cost. The criteria for selection of permanent magnet material are reviewed, and the major advantages to using this type of motor in comparison with a wound field dc motor are specified.     

Design optimization of permanent magnet synchronous motors for high torque capability and low magnet volume

Permanent magnet synchronous motors are being manufactured and used increasingly in low to medium power range applications due to their inherent advantages. There is a great deal of opportunity to enhance their merits by design optimization, thus reduce production costs and improve performance of the motors. In this paper a design optimization is performed on interior type permanent magnet synchronous motors to achieve high torque development capability with low permanent magnet consumption. A multi-objective optimization is performed in search for optimum magnet dimensions and location. The design optimization results in a motor structure superior to original motor specifications. Finite element method is used to evaluate the accuracy of the results.     

复合结构混合永磁电机抗退磁性能分析及优化

针对传统稀土永磁电机的稀土永磁材料用量高的问题,本文提出一种由钕铁硼和铁氧体混合永磁的交替极加局部Halbach结构的少稀土永磁同步电机,分析了该复合结构混合永磁电机的结构特点。比较分析了该电机与传统一字型钕铁硼稀土永磁电机的电磁性能,并依据退磁特性建立了该电机的局部退磁有限元模型,通过磁路耦合联合仿真对电机多运行工况进行了仿真,针对高速弱磁和变载运行工况下电机局部退磁的性能损耗,以提高永磁体工作点和降低退磁率为优化目标,给出了该电机的抗退磁优化设计方案。仿真结果验证了所提电机结构的合理性,电机抗退磁性能较优化前提升了10.3%。     

永磁无刷直流电机的电磁耦合器优化控制研究

永磁无刷直流电机的电磁耦合器是实现感应电能传输的重要器件,通过对电磁耦合器的优化控制设计,提高电磁耦合器的稳定性和输出增益。提出一种基于优化粒子群算法的电磁耦合器优化控制方法,首先进行了永磁无刷直流电机的电磁耦合器的等效电路设计,构建电磁耦合器控制的约束参量模型,以输出电压增益、功率损耗与效率为约束参量构建控制目标函数,实现控制算法的改进,进行了永磁无刷直流电机的电磁耦合器的优化设计。仿真实验结果表明,能有效提高永磁无刷直流电机的电磁耦合的输出稳定性,电机输出的电流增益、电压增益与输出效率高于传统方法,展示了较好的应用价值。     

基于改进遗传算法的永磁同步电动机优化设计

由于永磁体在永磁同步电动机成本中占有一定比例,在保证电机性能指标的前提下,对永磁体体积进行优化.同时介绍了改进遗传算法在电机优化设计中的应用,并对采用基本遗传算法和改进遗传算法的优化设计结果进行比较,得出了改进遗传算法寻优收敛速度较快,优化结果精度较高的结论.     

双三相永磁同步发电机多目标优化设计

为实现双三相永磁同步发电机(PMSG)的低固有电压调整率、高发电效率和低成本的特性,研究了侧重于降低固有电压调整率的多目标优化设计方案。采用解析法建立单元电机磁链模型,以永磁体磁化方向长度、永磁体所跨弧长和单元电机相绕组匝数为设计变量,分析上述参数对固有电压调整率、发电效率等评价指标的影响,并提出了基于权重系数的多目标优化函数。分别用标准遗传算法(SGA)、差分进化算法(DE)和基于以上2种算法的混合遗传算法(HGA)优化设计参数并进行对比。试验结果表明,HGA优化效果与设计目标具有良好的一致性,与初始设计参数相比,优化后的电机输出能力以及稳压能力均有所改善。