Updating Structural System Parameters Using Frequency Response Data

2000 ◽  
Vol 126 (12) ◽  
pp. 1240-1246 ◽  
Author(s):  
Philip D. Cha ◽  
James P. Tuck-Lee
Keyword(s):  
Frequency Response ◽  
Structural System ◽  
System Parameters ◽  
Response Data

Identification of Multi-Input Multi-Output Linear Systems From Frequency Response Data

1982 ◽  
Vol 104 (1) ◽  
pp. 58-64 ◽  
Author(s):  
P. L. Lin ◽  
Y. C. Wu
Keyword(s):  
Frequency Response ◽  
Composite System ◽  
Transfer Functions ◽  
Generalized Least Squares ◽  
Minimal Realization ◽  
Minimal Order ◽  
System Parameters ◽  
Response Data ◽  
Output System ◽  
Individual Input

A procedure for identifying a multi-input multi-output linear system from frequency response data is developed. Individual transfer functions from individual input to individual output are identified via the generalized least-squares theory. Orders of the transfer functions are determined by testing the residual. The minimal order multi-input multi-output system is identified based on the formation of a composite system comprising the subsystems associated with all individual outputs followed by decomposition. This is actually the problem of minimal realization involving inexact system parameters.

Damping Matrix Identification Using the Spectral Basis Technique

1988 ◽  
Vol 110 (3) ◽  
pp. 332-337 ◽  
Author(s):  
J. Fabunmi ◽  
P. Chang ◽  
J. Vorwald
Keyword(s):  
Frequency Response ◽  
Mass Matrix ◽  
Structural System ◽  
Linear Combinations ◽  
Response Data ◽  
Damping Matrix ◽  
Linearly Independent ◽  
Forced Responses ◽  
Pseudo Inverse ◽  
Basis Vectors

This paper presents a method for estimating the damping matrix of a structural system when the stiffness matrix, mass matrix, and frequency response data are given. The method is based on the fact that the forced responses of a structure can be decomposed into linear combinations of sets of frequency-dependent function. A set of orthonormal basis vectors of the frequency response is first determined. The forced responses are then expressed as linear combinations of these basis vectors. The coefficients of the damping matrix are then solved using the pseudo inverse of these basis vectors. Because the vectors that span the space of the frequency response are required to be linearly independent, an orthogonalization process is used to identify the number of significant basis vectors. Several examples are presented to illustrate the use and advantages of the proposed method.

scholarly journals Impact of the Generation System Parameters on the Frequency Response of the Power System: A UK Grid Case Study

Electricity ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 143-157
Author(s):  
Jovi Atkinson ◽  
Ibrahim M. Albayati
Keyword(s):  
Power System ◽  
Frequency Response ◽  
Power Grid ◽  
Sudden Increase ◽  
Generation System ◽  
System Parameters ◽  
Primary Frequency ◽  
Primary Frequency Response ◽  
The Impact ◽  
System Inertia

The operation and the development of power system networks introduce new types of stability problems. The effect of the power generation and consumption on the frequency of the power system can be described as a demand/generation imbalance resulting from a sudden increase/decrease in the demand and/or generation. This paper investigates the impact of a loss of generation on the transient behaviour of the power grid frequency. A simplified power system model is proposed to examine the impact of change of the main generation system parameters (system inertia, governor droop setting, load damping constant, and the high-pressure steam turbine power fraction), on the primary frequency response in responding to the disturbance of a 1.32 GW generation loss on the UK power grid. Various rates of primary frequency responses are simulated via adjusting system parameters of the synchronous generators to enable the controlled generators providing a fast-reliable primary frequency response within 10 s after a loss of generation. It is concluded that a generation system inertia and a governor droop setting are the most dominant parameters that effect the system frequency response after a loss of generation. Therefore, for different levels of generation loss, the recovery rate will be dependent on the changes of the governor droop setting values. The proposed model offers a fundamental basis for a further investigation to be carried on how a power system will react during a secondary frequency response.

Estimation of Transformer Winding Capacitances through Frequency Response Analysis – An Experimental Investigation

2013 ◽  
Vol 14 (6) ◽  
pp. 549-559 ◽  
Author(s):  
Krupa Shah ◽  
K. Ragavan
Keyword(s):  
Frequency Response ◽  
Wide Frequency Range ◽  
Response Analysis ◽  
Voltage Distribution ◽  
Response Data ◽  
Non Invasive ◽  
Transformer Winding ◽  
Invasive Method ◽  
Ladder Network ◽  
Good Agreement

Abstract This article focuses on developing a non-invasive method for determining capacitances using frequency response data. The proposed methodology involves acquiring driving-point impedance of the winding under consideration over wide frequency range. With certain terminal conditions and using the terminal impedance measured at specific frequencies, input and shunt capacitances are determined. For the purpose of estimating series capacitance of the winding, an algorithm is proposed. To demonstrate the capability of the method, initially model coils that have provisions for connecting external capacitances are considered. Then, it is found that the estimated values of capacitances are nearly same as those of connected capacitances. The method is, then, extended to transformer winding, and a capacitive ladder network is constructed. To assess the accuracy of estimation, capacitive voltage distribution is utilized. That is, the voltage distribution in the winding is compared with that of synthesized circuit. A good agreement between those data reveals that the estimated capacitance values are accurate.

Mechanical Contact Frequency Response Measurements

2000 ◽  
Vol 122 (4) ◽  
pp. 828-833 ◽  
Author(s):  
S. S. Kupchenko ◽  
D. P. Hess
Keyword(s):  
Frequency Response ◽  
Phase Lag ◽  
Lithium Grease ◽  
Mineral Oils ◽  
Vibration Data ◽  
Response Data ◽  
Lubricated Contacts ◽  
Wide Range ◽  
Contact Frequency ◽  
Dry Conditions

This paper presents friction frequency response measurements taken from a planar steel contact subjected to controlled random broadband normal vibration. Data are included from both dry and various lubricated contact conditions under different vibration input levels and different sliding velocities. Frequency response data for dry contacts are found to have nearly steady magnitude and negligible phase lag over a relatively wide range of frequencies. This suggests a coefficient of friction, independent of frequency but dependent on levels of normal acceleration and sliding velocity, may adequately define the dry contact frequency response. The frequency response data for lubricated contacts are mixed. For example, with MoS2 grease the frequency response may adequately be defined by a constant, as with dry conditions. However, frequency response data for contacts with pure mineral oils, mineral oils with additives, and lithium grease are found to be dependent on frequency. [S0742-4787(11)00101-9]

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