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Resonance for Multitransducer Systems
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Electrical resonance is frequently encountered during the design of electrical systems and circuits and is often modeled as a series or parallel RLC network. It is also common practice to use an equivalent electrical network to represent the operation of a mechanical resonator [25,26]. The reason for this conversion, besides its familiar presentation to electrical engineers, is that the resonator model can then be used in circuit simulators along with the interface electronics for that system, and hence, performing a more comprehensive analysis of the system. Table 31.1 illustrates the correspondence between the equivalent electrical and mechanical models of a resonator. When the resonator is modeled around its resonant frequency, the equivalent electrical models are called motional resistance, motional inductance, and motional capacitance. The motional resistance, Rm, is particularly important as it represents the resonator losses.
Textile-based 3D metamaterial absorber design for X-band application
Published in Waves in Random and Complex Media, 2022
Ediz Erdem, Ahmet Hayrettin Yuzer
The incident electromagnetic wave on the medium should not be reflected instead of transmitted from the medium to obtain perfect absorption. It should be absorbed in the medium. With its three-layered structure, impedance matching is done and so that the incident electromagnetic wave is not reflected. The conductive layer prevents transmitting the electromagnetic wave. When the shapes of the periodic resonator layer match with the sub-wavelengths of the incident electromagnetic wave, it creates a surface current on the periodic resonator. It causes electrical resonance. The conductive layer will create a reverse current to the surface current. This causes magnetic resonance. When the electrical and magnetic resonance are obtained simultaneously, and the dielectric layer is lossy, an excellent absorbent is obtained. The generated surface currents are absorbed in the metamaterial and turn into heat energy [22,29,30].
Modal Analysis on Control Impact of Fully Rated Converters-Based PMSG-WECS Connected to Turbine-Generator
Published in Electric Power Components and Systems, 2021
Janaki Muneappa Reddy, Thirumalaivasan Rajaram, Yunjian Xu
When, the FRC-based PMSG-WECS is incorporated, the equivalent reactance (Xeq) of the system is altered as shown in Figure 11. It is to be observed that, the magnitude of the equivalent reactance (Xeq) sags in low frequency region of electrical resonance frequency, whereas swells in high frequency region. This indicates that there is a rise in equivalent inductance reactance of the system by PMSG-WECS. As a result, the electrical resonance frequency (ωer) reduces [35]. The electrical resonance frequency occurs about 269 rad/sec in case-1. The complement of electrical resonance frequency found in graphical resonance condition for case-1 is ωm = ωo – ωer = 377 − 269 = 108 In case-3, the electrical resonance frequency occurs about 272 rad/s. The complement of electrical resonance frequency found in graphical resonance condition for case-3 is ωm = ωo – ωer = 377 − 271.5 = 105.5 From the graph of resonance condition in Figure 11, it is clear that, the PMSG-WECS slightly increases the equivalent inductive reactance of the system, thereby slightly increases the frequency of subsynchronous network mode (ωo – ωer).
An Integrated Electromechanical Model of the Fixed-Speed Induction Generator for Turbine-Grid Interactions Analysis
Published in Electric Power Components and Systems, 2018
Da Xie, Wangping Wu, Xitian Wang, Chenghong Gu, Yanchi Zhang, Furong Li
Several types of oscillations occur frequently, such as electrical resonance, SSI including subsynchronous resonance (SSR), subsynchronous oscillation (SSO), and low-frequency oscillation [8]. Electrical resonance will occur and DFIGs provide energy for this resonance continuously, if there is system equivalent inductance x ≃ 0 at certain subsynchronous frequency [9]. SSR is a condition where the wind farm exchanges energy with the power grid at one or more natural frequencies of the electrical or mechanical part of the power system [10]. Frequency of this energy exchange is below the fundamental frequency of the system, and this may result in shaft failure [11]. There is a risk of subsynchronous control interaction (SSCI) even if the level of compensation is very low, such as less than 10%. However, the probability of occurrence of SSR is greatly reduced [12] and [13]. SSO and harmonic resonance can occur between Wind Farms and high voltage direct current (HVDC) systems [14]. The oscillations can appear in the presence of background harmonics and is arguably resulting from the controller interaction of the wind energy conversion system (WECS) converter controller and HVDC converter controller [15]. Low-frequency oscillations occur when the rotors of machines, behaving as rigid bodies, oscillate with respect to each other using the electrical transmission path between them for exchanging energy [16]. In the conventional boost converter with pulse train (PT) control, the output voltage will produce undesirable low-frequency oscillation in continuous conduction mode [16].