An improved cuckoo search algorithm and its application in vibration fault diagnosis for a hydroelectric generating unit

This article presents an improved cuckoo search (ICS) algorithm based on the parametric adaptation mechanism and non-uniform mutation. In the ICS algorithm, the biased random walk operator is modified to take advantage of the neighbourhood information of the current solution, and then the control parameters of step size, discovery probability and scaling factor are directly integrated into the optimized problems. Meanwhile, the non-uniform mutation operation is used to adaptively tune the search step of the current optimal solution. To evaluate the feasibility and efficiency of the presented algorithm, three groups of benchmark test functions are employed to perform the validation analysis. Subsequently, to diagnose the vibration fault of a hydroelectric generating unit, a combinational model is built, which combines ICS with a back-propagation neural network (ICSBP). The experimental results indicate that ICS is competitive on the optimization problems, and the ICSBP approach can effectively improve the accuracy of vibration fault diagnosis for a hydroelectric generating unit.     

深部松软煤层钻孔孔周煤体变形产渣特征研究

针对煤矿井下高瓦斯软煤顺层长钻孔排渣困难、成孔率低、施工困难等问题,通过数值模拟实验研究了井下深部软煤体变形破坏特征,分析了顺层长钻孔孔周松软煤体变形特征及应力变化,以揭示顺层长钻孔孔周松软煤体变形产渣规律。研究表明:深部高瓦斯软煤顺层钻孔孔周煤体的应力平衡临界条件破坏后将发生大体积突然垮落;钻孔水平最大变形位移为1.22mm,垂直方向最大变形位移为10.7mm;径向孔周煤体垂向变形呈现逐渐减小趋势,且垂向变形明显大于钻孔水平变形。在水平方向上,钻孔孔周煤体应力分布呈现先增大再逐渐减小的变化规律,径向距离对水平应力分布的影响逐渐减小;随着径向距离的增加,钻孔孔周煤体应力分布逐渐降低,钻孔孔壁处煤体的应力出现最大值,且垂直方向处应力值最大。     

Availability growth models and verification of power equipment

The general availability growth models for large scale complicated repairable system such as electric generating units, power station auxiliaries, and transmission and distribution installations are presented. The calculation formulas for the maintenance coefficient, mathematical expressions for general availability growth models, ways for estimating, and fitting on checking the parameters of the model are introduced. Availability growth models for electric generating units, power station auxiliaries, and transmission and distribution installations are given together with verification examples for availability growth models of 320–1000 MW nuclear power units and 1000 MW thermal power units, 200–1000 MW power station auxiliaries, and 220–500 kV transmission and distribution installations. The verification results for operation availability data show that the maintenance coefficients for electric generating units, power station auxiliaries, transmission and distribution installations conform to the power function, and general availability growth models conform to rules of availability growth tendency of power equipment.     

矿用锚链轮齿形加工方法对其使用性能的影响

说明了成形法加工锚链轮是使用其性能变差的关键因素 ,说明了展成法是锚链轮齿形加工的合理加工法。     

热电冷联产系统节能性的(火用)分析

利用分析的方法,定义了等效发电效率,对常用热电冷联产系统形式的节能性进行了分析。认为相对于全国平均供电煤耗而言,热电冷联产系统的节能是有条件的,应选取合理的方式,优化设计和运行方案;相对于当前有些热电厂夏季负荷不足的情况,热电冷联产是节能的,在不同的情况下节能率在7.8%~39%之间。建议利用现有的热电联产条件,发展热电冷联产系统,提高现有热电厂的设备利用率和运行经济性。     

太阳能光伏发电应用于公共建筑的探讨

太阳能光伏发电是一个新课题。研究这种电能的特点,结合我国国情,分析并入城市电网的可能性和必要性,提出建议在大型公共建筑采用的太阳能屋顶发电的配电方案。     

浙江省火力发电机组非计划停运统计及预防

通过对2015—2018年纳入浙江省技术监督管理系统的火力发电机组非计划停运事件的统计与分析,找出影响机组运行可靠性的主要故障原因和薄弱环节,为发电厂增强设备故障预防,加强运行、维护与管理等方面指明方向,提供建议及参考依据。     

渐近辨识建模法在1000 MW火电机组脱硝控制系统优化中的应用

介绍了渐近辨识法在某1000 MW火电机组脱硝控制优化建模中的应用。在SCR(选择性催化还原)原常规PID闭环控制系统正常运行的情况下,采用ASYM(基于渐近辨识方法)通过在SCR装置的喷氨量指令上叠加测试信号,在不干扰SCR装置正常运行的前提下,辨识获取了高精度SCR控制模型,并以此为基础搭建MPC控制器,大大改进了SCR反应器出口NOX浓度的控制品质。     

一种考虑多种保障因素的作战任务间歇期战备完好率评估模型

科学合理的战备完好性评估对于准确掌握部队实战能力,优化保障体系结构,提高装备作战能力与保障效能具有重要意义。针对现有评估模型注重维修保障因素而忽略供应保障因素、无法处理结构和状态较复杂的装备体系与保障体系问题,提出一种新的综合考虑多种保障因素的作战任务间歇期战备完好率评估模型。分析装备体系与保障体系之间的交互关系和保障过程,从装备保障需求角度出发构建装备体系中单个装备作战单元的战备完好率评估模型,在此基础上进一步构建共享同一保障体系多个装备作战单元的战备完好率评估模型。该模型考虑了装备作战单元装备保障需求相同与不同两种情况,并针对模型求解时装备体系状态难以确定的问题,给出一种基于向量通用函数的装备体系状态确定方法。通过实例分析验证了所提模型定量评估战备完好率的有效性和优越性。     

展成磨齿机磨削不同压力角渐开线圆柱齿轮的方法

展成磨齿机的砂轮磨削角为αs,当被磨削渐开线圆柱齿轮分度圆法向压力角αn不同于砂轮磨削角αs时,通过参数换算得出αjn=αs时的磨削节圆直径dj和磨削节圆螺旋角βj,使操作复杂的展成磨齿机可以磨削不同法向模数mn、不同分度圆法向压力角αn及不同齿数z等各类渐开线圆柱齿轮,减少更换修整磨削砂轮时间及工件的中间检测调整次数,提高展成磨齿机的综合效率。