Design of two-dimensional scaled state space filters with fixed point arithmetic

In this paper a new synthesis method has been proposed for the design of 2D scaled state space filters with fixed point arithmetic. It is based on constructing a non-singular transformation matrix which minimizes the output noise power and maintains the signal-scaling condition, besides zeroing some of the entries of the state matrices. As a result, simultaneous savings in both additions and multiplications are achieved. Numerical results are included to illustrate the performance of the proposed structures and to compare them with other structures.     

Recursive identification of a nonlinear state space model

The convergence of a recursive prediction error method is analyzed. The algorithm identifies a nonlinear continuous time state space model, parameterized by one right-hand side component of the differential equation and an output equation with a fixed differential gain, to avoid over-parametrization. The method minimizes the criterion by simulation using an Euler discretization. A stability analysis of the associated differential equations results in conditions for (local) convergence to a minimum of the criterion function. Simulations verify the theoretical analysis and illustrate the performance in the presence of unmodeled dynamics, by identification of the nonlinear drum boiler dynamics of a power plant model.     

Nonlinear state space model identification of synchronous generators

A method for identification of a synchronous generator is suggested in this paper. The method uses the theoretical relations of machine parameters and the Prony method to find the state space model of the system. Such models are useful for controller design and stability tests. The proposed identification method is applied to a third order model of a synchronous generator. In this study, the field voltage is considered as the input and the active output power and the rotor angle are considered as the outputs of the synchronous generator. Simulation results show good accuracy of the identified model.     

Design of fixed point state space digital filters with low round-off noise

A simple method is described for the design of fixed-point recursive digital filters with low round-off noise. the method is based on reducing to zero as many as possible of the coefficients of the filter state matrices. an optimization procedure is used to get the optimum value of linear transformation that minimizes the total output round-off noise power. Compared with the existing approaches, this method is characterized by its computational simplicity, very low output round-off noise (if not the lowest possible) and low coefficient sensitivity. the structure of the proposed technique is modular, which makes it suitable for VLSI implementation. the technique is then employed to obtain a reduced-order low-round-off-noise filter with characteristics equivalent to some desired FIR specifications. Illustrative examples are given to verify these advantages.     

基于状态空间模型的管路结构损伤识别系统

为避免管路系统事故发生,对管路系统的服役情况进行实时监测,以期及时发现装置结构隐患。本研究采用状态空间模型,以某高压蒸汽管路系统为研究对象,开发了一个科学、有效的损伤识别监测系统,基于振动信号检测管路系统中的失效与故障,全面地掌握管路系统的健康状态并进行预警。研究结果表明,在某些特殊情况下,系统能够很快予以调研且实时的输出监测信息,测试平均响应时间4.436 s与损伤识别准确率80%分别满足设计要求的响应时间小于20 s以及准确率大于70%,且由于基础理论和结构的适应性,该系统适用于各种类型的管道,并且可以针对一种或多种失效模式,具备较强的应用价值。     

First harmonic analysis: a circuit theory point of view

The first harmonic method is usually applied to nonlinear system analysis, being particularly adequate for the study of oscillations. As shown in this paper, oscillators analysis can be performed by using only basic concepts of circuit theory. The nonlinearities present in the oscillator electric circuits are approximated, via the first harmonic method, by resistance or source-controlled equivalent circuit elements, and the resulting linear circuits are entirely analyzed via conventional circuit theory. As a result, the analysis of electric oscillators and the first harmonic method are introduced in a comprehensible electric circuit context     

DC/DC变换器稳态运行谐波状态空间模型

针对传统的状态空间平均法在建模中损失纹波信息的缺陷,基于线性时间周期理论和谐波线性化理论,采用傅里叶分解法,建立DC/DC变换器稳态运行下的谐波状态空间模型,绘制DC/DC变换器的谐波等效电路,从频域角度描述拓扑电流和电压的映射过程;在输入侧加入小扰动,建立DC/DC变换器的谐波状态空间小扰动描述矩阵,对稳态谐波和扰动间谐波进行分析。仿真与实验结果表明,基于谐波状态空间的DC/DC电路建模方法具有极高的精确性,在未来多变流器的配网场景谐波分析中具有一定的工程运用价值。     

水力发电系统状态空间法自适应建模研究

对反映引水系统结构信息的节点进行了分类,并推导了主要类型节点状态变量的排序和状态方程的通用写法,从而使系统结构信息数字化,在此基础上提出了水力发电系统状态空间自适应建模方法并编写了自适应建模程序,通过具有复杂系统的梯级串联电站的算例说明了其自适应建模能力。为复杂的现代水力发电系统的状态空间法动态仿真和控制方案研究提供了强有力的工具。     

基于状态空间模型与PEM迭代算法的电力系统惯量辨识

惯量是保障电力系统频率安全稳定的重要参数之一,因此需对其进行精确的在线测量。针对当前采用的系统辨识方法测量精度不高的问题,研究系统辨识中算法模型的选择对测量结果的影响。首先,分析比较现有的传递函数模型、自回归滑动平均模型以及子空间辨识模型进行惯量辨识的测量原理。其次,从惯量响应初期阶段数据匹配的角度,提出基于PEM迭代算法的状态空间估计模型。最后,搭建10机39节点电力仿真系统,验证了所提辨识模型的正确性。并在不同功率扰动程度以及不同采样时间窗口下,分析4种辨识模型的适用性,为确定系统最优辨识模型提供参考依据。     

GIS insulation co-ordination: on-site tests and dielectricdiagnostic techniques. A utility point of view

This paper summarizes the Electricite de France experience with insulation coordination of gas-insulated substations (GIS). After a review of the insulation coordination practice, mainly dealing with fast front overvoltages and the one minute AC test, some results of the on-site test procedure applied for 30 years are presented and related to the insulation co-ordination practice. The in-service return of experience dealing with dielectric failures is analyzed. The dielectric diagnostic techniques now available are briefly presented with their possibilities and limitations. According to this survey, the expectations of EDF from these diagnostic techniques as well as the new on-site test and online monitoring tendencies at EDF are presented     

Networks containing periodically operated switches: A state space approach

A state space analysis is given of the networks containing periodically operated switches, by using a new approach based on the concept of time constant multiplication rather than on the conventional concept of resistance multiplication. The transfer function of two-port networks containing P.O.S. is derived from a state model that does not require a detailed topological analysis of the network. The number and the location of the switches is discussed with particular reference to the problem of their minimization. Experimental results are given by illustrating an application of variable filters to the realization of a spaceborne spectrum analyzer.     

从建筑电气设计角度浅析火灾的防范

近年来 ,由于电气线路故障引起的火灾事故增多 ,如何杜绝火灾隐患 ,本文从导线截面选择、线路敷设、电缆选型等几个方面作了介绍。