基于前景理论和灰关联分析法的黑启动方案优选

为了解决电力系统恢复过程中黑启动方案优选问题,提出了基于前景理论和灰色关联理想解法的黑启动方案优选模型。结合相关资料,构建了电力系统黑启动方案的综合评价指标体系。运用（TOPSIS）灰关联理想解法和灰关联分析法构建了正（负）关联系数矩阵;再基于前景理论及其正负前景价值函数构成了正（负）前景价值矩阵和黑启动方案综合前景值最大化的约束非线性优化模型,求解模型得出各方案的综合前景值;得到综合前景值最大的黑启动方案。通过实例验证了所提模型的科学性和实用性,且模型的决策灵敏度很好。     

基于可拓理论的变压器状态综合评估

笔者基于可拓理论,提出了一种可拓评价法和可拓层次分析法相结合的变压器状态综合评估方法。首先,采用可拓层次分析法(EAHP),将变压器状态信息之间的相对重要度采用一个可拓区间数来表示,构造可拓判断矩阵,准确计算变压器状态信息指标的权重。然后,应用可拓评价法,通过计算物元之间的关联函数同时进行定性和定量分析,实现变压器状态的综合评估。实例分析证明了该方法的正确性和有效性,为变压器的状态维修提供了合理的决策依据。     

基于最小叉熵与前景理论的综合能源系统评价方法

综合能源系统可以提高能源供应的可靠性和灵活性,具有良好的经济效益和环境效益。综合能源系统评价对综合能源系统项目实施具有重要意义。提出了一种基于最小叉熵模型和前景理论的综合能源系统评价方法。首先,采用最小叉熵模型求得各评价指标的综合列向量。其次,根据差异性权重法确定出指标权重。最后通过建立正、负前景值矩阵,根据得到的综合前景值大小完成综合能源系统方案的优劣排序。采用上海某宾馆综合能源系统数据集验证了所提方法的有效性。     

基于云模型和灰关联投影法的烟气脱硫技术优选

针对烟气脱硫技术优选中存在自然语言型评价信息和评价指标间具有灰色关联性的问题,提出基于云模型和灰关联投影法的烟气脱硫技术综合评价模型。由技术性指标、经济性指标、环保性指标构成烟气脱硫技术综合评价指标体系。通过层次分析法确定指标的主观权重,采用熵权法确定指标的客观权重,基于加法原理融合主客观权重信息得到各指标的综合权重值。利用云模型表示自然语言型评价信息,实现了定性概念向定量表示的合理转换。在此基础上,结合灰色系统理论和矢量投影原理,计算评价对象的优属度,实现烟气脱硫技术方案优选。通过对6种有代表性的烟气脱硫技术进行比较分析,表明该模型具有客观科学、简单有效、灵敏度高的优点,能够为烟气脱硫技术优选提供可靠的决策依据。     

基于区间权重和改进云模型的变压器状态评估

针对变压器状态等级边界信息随机性和模糊性的问题,提出建立基于正态云理论的变压器状态评估模型。考虑变压器状态评估数据的有限性,提出对变压器少数运行数据进行正态云处理。对于变压器等级边界模糊性问题,提出对变压器各等级进行适度扩展,建立变压器指标等级正态云。根据不同云滴在数据正态云出现的不同概率,计算变压器数据正态云云滴与各评估指标等级正态云之间的关联度,得到评判矩阵。其次,对变压器运行数据进行区间表示。针对各指标区间数据的波动性,计算区间数据的方差和平均差,进而赋予指标不同的权重,在此基础上进行变压器状态评估。通过分析某台变压器运行数据,验证了该方法应用于变压器状态评估中的有效性。     

基于灰色理论的电力变压器运行状态评估

本文提出了一种基于灰色理论的电力变压器运行状态评估方法,建立了变压器运行状态评估模型。该方法首先运用改进后的非等间隔GM(1,1)模型和缓冲算子GM(1,1)模型对已知的变压器油色谱试验信息进行分析预测,再对其进行评分,根据评分结果将变压器综合运行状态进行分类,并给出相应的维修策略,从而为变压器的检修和维护提供相应的技术依据。实例评估分析表明,该评估方法是可行实用的。     

基于灰色累积前景理论分布式电源投资风险型决策

针对分布式电源投资决策问题,在选取经济效益和环境效益作为投资决策分析指标的基础上,考虑到决策者主观风险态度对分布式电源投资的实际影响,设定了投资项目的影响参数,提出一种基于累积前景理论的分布式电源投资项目灰关联分析决策模型。该方法首先引用奖优罚劣线性变换算子将初始决策矩阵进行标准化处理,并借鉴TOPSIS方法以正负理想方案作为决策的参考点,将灰关联分析法融入累积前景理论中构建了正负前景价值矩阵,进而以各方案综合前景值最大化构建权重函数优化模型,通过Matlab软件编程求解模型得出最优权重,据此得出各投资项目的综合前景值及排序。最后通过实例分析验证了该模型的科学性和合理性,为分布式电源的投资决策提供一种新的思路和方法,,     

基于模糊综合评价的变压器状态评分方法研究

状态维修是变压器维修策略的发展方向,准确对变压器状态进行量化评分是状态维修的基础工作。目前变压器状态评分方法较少,已有的方法多为定性评价,也有文献提出了对电气设备状态信息进行评分并加权处理的方法,但评分方法比较简单且缺乏客观依据。基于此本文提出了一种综合考虑变压器状态信息,将变压器状态信息评分与模糊综合评价相结合的变压器状态评分方法和步骤。实例分析表明了该方法的有效性和实用性。     

基于模糊综合评价的变压器状态评分方法研究

状态维修是变压器维修策略的发展方向,准确对变压器状态进行量化评分是状态维修的基础工作.目前变压器状态评分方法较少,已有的方法多为定性评价,也有文献提出了对电气设备状态信息进行评分并加权处理的方法,但评分方法比较简单且缺乏客观依据.基于此本文提出了一种综合考虑变压器状态信息,将变压器状态信息评分与模糊综合评价相结合的变压器状态评分方法和步骤.实例分析表明了该方法的有效性和实用性.     

基于DGA的反馈云熵模型电力变压器故障诊断方法研究

为了解决变压器故障诊断中存在的随机性和模糊性问题,提出了基于反馈云熵模型的电力变压器故障诊断新方法。通过对大量电力变压器故障征兆及故障类型的统计分析,并将其视作云滴输入贝叶斯反馈逆向云发生器中,得到故障特征气体的云模型参数值,构建变压器故障诊断标准正态云模型。将云关联系数和信息熵理论有机结合起来,降低了对单个标准正态云模型的依赖性,充分挖掘变压器油中溶解气体所包含的故障信息,提高了变压器故障诊断的准确率。通过不断丰富输入样本、修正云模型参数值的方法,可以进一步提高模型诊断效果。实例分析结果表明该模型的故障诊断准确率较高,并具有较好的理论价值和应用前景。     

Capacitor theory

A new linear capacitor model is proposed. It is based on Curie's empirical law of 1889 which states that the current through a capacitor is i(t)=U₀/(h₁tⁿ), where h₁ and n are constants, U₀ is the dc voltage applied at t=0, and 0i(t)=h₁tⁿ, that is, it increases almost in proportion to time since n nearly equals 1.0. For a general input voltage u(t) the current is i(t)=Cdⁿu(t)/dtⁿ where use is made of the fractional derivative, defined by means of its Laplace transform. The model gives rise to a capacitor impedance Z(iω=1/[(iω)ⁿC], with a loss tangent that is independent of frequency. The model has other properties: the capacitor `remembers' voltages it has been subjected to earlier, dielectric absorption is an example of this. Capacitor problems require solving integral equations. The model is dynamic, i.e. electrostatic processes are simply slow dynamic processes. The model is applied to several problems that cannot be treated with conventional theory     

Number theory

Number theory, an abstract branch of mathematics that deals with relationships between whole numbers, has provided highly useful answers to numerous real-world problems. The author briefly reviews earlier uses of number theory and then examines recent applications to music, cryptography, and error-correction codes     

Cmos latchup theory

The purpose of this paper is to study the CMOS latchup phenomenon from a non-linear circuit theoretic standpoint by using some recently developed results on negative-resistance devices. We introduce a simple mechanism to describe the latchup phenomenon based on a special circuit topology called feedback structure, which is shown to be responsible for the occurrence of latchup. Several guidelines are proposed to prevent latchup by destroying the feedback structure. In addition to the characterization of the steady-state behaviour, we use a first-order circuit model to analyze the latchup dynamics during the turn-on process and give a stability analysis of the circuit dynamics. All existing techniques to prevent latchup are shown to follow naturally from our guidelines, which are derived using nonlinear circuit theory.     

Generalized transmission line theory as an antenna theory for EMC analysis

This contribution exhibits the equivalence between generalized transmission line theory and antenna theory, as applied to thin-wire structures. While in antenna theory focus is put on the direct solution of appropriate field integral equations, in the derivation of generalized transmission line theory the relevant field integral equations are first transformed into equivalent generalized Telegrapher equations and eventually solved by methods which are tailored to transmission line theory. This is illustrated by two examples that exemplify the use of generalized transmission line theory in EMC analysis for the investigation of radiating transmission line systems.     

Using fuzzy set theory

Two main trends are mentioned: the fuzzy set theory and the fuzzy logic. Both build upon set theory and logic, respectively. Three features distinguish the approaches: (1) the use of so called linguistic variables, instead of or together with numeric variables; (2) the use of fuzzy conditional statements to represent simple relations between variables; and (3) the characterization of complex relations by fuzzy algorithms. Fuzzy linguistic variables and fuzzy algorithms offer an effective, more flexible way to describe a system's behavior too complex for a classical mathematical model. They are very successful in economics, management science, artificial intelligence, information retrieval systems, pattern recognition, image processing, psychology, biology, and other fields rendered inherently fuzzy do to the unpredictable behavior of their components. Expert systems, fuzzy neural computing and pattern recognition are discussed in some detail     

Network theory and CAD

Methods used to teach fundamental network theory and computer-aided design of analog networks are discussed. It is shown that although the classical nodal and mesh formulations are needed for hand calculations, students should also get information about modified nodal analysis. It is also shown that DC solutions of linearized networks can easily be explained by using modified nodal formulation and the simplest numerical integration formula     

Teaching electrodynamic levitation theory

A theoretical approach to teaching the principles of electrodynamic levitation is described. Two theories are used to obtain analytical solutions to predict the performance of a simple MAGLEY arrangement. The first theory, based on Maxwell's equations and vector force relationships, is for a simplified model allowing for a finite-thickness track conductor. The second theory is for a thin plate track and is a straightforward calculation of the lift and drag forces for a particular electromagnetic repulsion geometry, involving solution by one-dimensional integral equations. The magnetic flux source travels at a constant velocity and is derived from a sinusoidally distributed current sheet which in practice can be derived from windings or permanent magnets. Edge and end effects are neglected in both cases, which is equivalent to assuming infinite iron above the excitation surface and below the conducting plate. The simplified theory is illustrated quantitatively by a laboratory experiment in which a tray of permanent magnets is suspended over a rotating conducting plane. Gap magnetic field and drag force are measured as functions of velocity. The theoretical approach allows the following aspects to be investigated: the magnetomotive force and physical dimensions to produce suitable field magnitudes and measurable forces; the effect of harmonics by practical measurement of field profiles; and the effect of skin depth and conducting plate dimensions     

基于博弈论和概率论的发电商竞价策略研究

电力市场环境下,发电公司可以通过策略性投标来获得最大利润.在分析策略性报价研究现状的基础上,建立了基于博弈论和概率论的发电报价数学模型,结合发电公司追求利润最大化的目标,对发电公司竞标成功的概率进行了详细的分析,通过比较发电报价与市场出清价两者之间大小关系的可能性概率及其数学期望的求解,给出了满足发电公司期望效用函数最大的最优报价策略方法.算例分析的结果验证了该方法的有效性和可操作性.     

Lyapunov和最优控制理论相结合的非线性励磁控制器设计及仿真

把Lyapunov稳定性理论和最优控制理论相结合应用于单机无穷大系统设计励磁控制器，推导出发电机非线性最优励磁控制规律。并对推导出的控制规律在Matlab的Simulink环境下进行仿真，仿真结果表明，利用此方法设计的控制器对于扰动有较好的控制效果，能很快使扰动产生的暂态过程得到抑制。改进了电力系统的稳定性能。