Bacteria foraging optimization algorithm based load frequency controller for interconnected power system

Social foraging behavior of Escherichia coli bacteria has recently been explored to develop a novel algorithm for distributed optimization and control. The Bacterial Foraging Optimization Algorithm (BFOA), as it is called now, is currently gaining popularity in the community of researchers, for its effectiveness in solving certain difficult real world optimization problems. This paper proposes BFOA based Load Frequency Control (LFC) for the suppression of oscillations in power system. A two area non-reheat thermal system is considered to be equipped with proportional plus integral (PI) controllers. BFOA is employed to search for optimal controller parameters by minimizing the time domain objective function. The performance of the proposed controller has been evaluated with the performance of the conventional PI controller and PI controller tuned by genetic algorithm (GA) in order to demonstrate the superior efficiency of the proposed BFOA in tuning PI controller. Simulation results emphasis on the better performance of the optimized PI controller based on BFOA in compare to optimized PI controller based on GA and conventional one over wide range of operating conditions, and system parameters variations.     

A Method for Presuming Total Output Fluctuation of Highly Penetrated Photovoltaic Generation Considering Mutual Smoothing Effect

Mutual smoothing effect of renewable energy (RE) is quite important because the amount and cost of countermeasures for maintaining soundness of power systems highly depend on evaluation of the effect. In spite of its importance, there is as yet no established method to evaluate the effect. The authors present a method for presuming the total output fluctuations of highly penetrated RE from a few measured data considering the effect. By analyzing the measured data, existing photovoltaic (PV) output fluctuations are revealed to be coherent at slower swing periods and random at faster swing periods. To represent the PV’s output fluctuation tendencies, a “Transfer Hypothesis” is introduced. A “Constant Transfer Swing Period Hypothesis” and “–20 dB/dec Slope Hypothesis” are also introduced. These hypotheses are verified by direct and indirect methods using the measured data. Only 3 sites’ data are able to presume total fluctuation of 15 sites successfully. The relationship between distance and the transfer swing period for every 2 sites out of the 15 sites agrees with these hypotheses. Finally, the authors show the total fluctuation presumption of highly penetrated PV deployment in the Hokuriku region using the proposed methods. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 31–42, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22327     

消失模EPS模型材料表征及性能的研究

为了探究消失模EPS模型的表面粗糙度影响因素、应力应变特征以及消失模EPS模型材料的热解规律和内部胞腔结构形态,达到降低消失模铸件的表面粗糙度,科学制定消失模工艺过程的控制参数,选择适合消失模工艺的合金材料,控制铸件内碳化物残留量,提高消失模铸件的表面质量和力学性能.本文采用激光粒度分析仪对用于消失模EPS产品模型成形...     

复杂曲面零件消失模发泡模具设计与制造

分析了不同类零件在消失模发泡模具开发过程中的关键技术,重点针对具有复杂曲面的管接头和阀体类零件,结合UG Modeling & Manufacturing软件平台,论述了三维造型、模具设计和数控编程在整个工艺路线中的使用要点,总结了行之有效的方法和经验。     

Current state of neural networks applications in power system monitoring and control

For over two decades Neural Network (NN) has been applied to power system monitoring and control. Conventional controllers suffer from certain limitations which NN as an Artificial Intelligence (AI) technique is able to overcome. Therefore, many researchers prefer to use NN technique in the monitoring and control of power systems. This paper reviews published recently schemes for control and monitoring based on NN. The performance of various NN controllers is compared with one another as well as to the performance of other types of controllers. This review further reveals that the design of a proper NN control can maintain first-swing stability, damp oscillation, ensure voltage stability and the reliable supply of electric power.     

长条对称型消失模铸件的收缩不均性分析

通过对“特殊横壁”铸件的试验测试发现，长条对称型消失模铸件，如采用不同的浇注方案，其铸件的收缩率相差较大，采用水平卧式浇注，铸件对称的两边收缩率基本相同，而采用垂直立式浇注，铸件对称的上下收缩率相差较大，分析了长条对称型消失模铸件收缩不均性的原因，对此类铸件的工艺设计原则及浇注方案的确定进行了初步探讨。     

消失模铝铸件针孔形成机理研究

探讨了铝液变质、晶粒细化、浇注温度及聚苯乙烯模样等对消失模铝铸件针孔的影响 .研究结果表明 ,干砂消失模铸造工艺冷却速度比树脂砂工艺和粘土砂工艺慢 ,更易产生针孔 ;若用0 .2 %Ti对消失模铸造铝液进行细化处理 ,则可以大大减少冷却速度慢对其针孔形成的不利影响 ,使铝件密度接近或达到树脂砂工艺的水平 .为减少针孔 ,应尽量采用低密度的聚苯乙烯模样 ,并应有一个适当高的浇注温度