Point Impedance Research Articles

Optimal distributed generation planning in distribution networks: A comparison of transmission network models with FACTS

In Distributed Generators (DG) optimal planning solutions, transmission section is modelled as an ideal voltage-controlled bus at 1.0 pu., this ignores the impacts of Flexible Alternating Current Transmission Systems (FACTS). However, modern transmission networks include optimally placed FACTS for improved power quality. Moreover, voltages at Point of Common Coupling (PCC) between transmission and distribution networks varies with FACTS control operations. Hence, these can result in local optimal DG planning solutions. In this paper, a two-bus Thevenin’s equivalent model of transmission section to account for FACTS is proposed. Hybrid line voltage stability indices and particle swarm optimization (LVSI-PSO) obtain a reduced search space, location and sizes of FACTS at transmission section, while Particle Swarm Optimization (PSO) is used to locate and size DG in the distribution section of the test system. The test system is an integrated transmission-distribution network; with modified IEEE 9 bus as transmission section and IEEE 16 node as distribution section. Modification of driving point and transfer impedance of Zbus matrix account for Thyristor Controlled Series Compensator (TCSC) and Static Var Compensator (SVC). Results show that solutions obtained with transmission network modelled as an ideal voltage-controlled bus is a local optimal solution compared with integrated transmission-distribution network model and Thevenin’s equivalent model. The Proposed Thevenin’s equivalent model through parameter estimations Eth and Zth closely matches results from the integrated test system.

Boundary Analysis for the Derivative of Driving Point Impedance Functions

Four theorems are presented in this brief by performing boundary analysis of the derivative of driving point impedance functions evaluated at the origin. Also, the circuits corresponding to these driving point impedance functions, which are obtained as the natural results of presented theorems, are given. Driving point impedance functions are mainly used for synthesis of networks containing RL, RC, and RLC circuits. Considering that the driving point impedance function, ${Z(s)}$ , is an analytic function defined on the right half of the s- plane, we derive inequalities for the modulus of the derivative of driving point impedance function, ${|}{Z}^{\prime } {(0)|}$ , by assuming the ${Z(s)}$ function is also analytic at the boundary point ${s=}{0}$ on the imaginary axis with ${Z(0)=}{0}$ . Finally, the sharpness of these inequalities are proved. Unique driving point impedance functions are obtained as intuitive results of presented theorems in the study and it is also shown that the extremal functions correspond to the driving-point impedances of simple LC circuits.

Estimation of body input force transmission change due to parts’ modification using the impedance method under rolling excitation

This study aims to estimate the change in suspension to body input force transmission due to the softening of the connecting elastomer under rolling excitation. In this respect, the suspension coupled to a vehicle body via an elastomer bushing is modeled using point impedance. A numerical study is performed for achievable force reduction due to a softened bush under the influence of different impedance combinations for the suspension and the vehicle body. Following a numerical study, the proposed model is validated through empirical testing of McPherson strut type suspension in the lateral arm Y direction and multilink type rear suspension in the front mount X direction, which represent extremely stiff and extremely soft coupling cases for the suspension type, respectively. Due to the difficulties in measuring road-induced operational forces within an actual vehicle, a validation test is performed using a previously developed rig that enables direct measurement of the force without modifying the structure of the suspension. Additionally, the rig-measured force, which is potentially misleading due to the large deviation in stiffness between the rig and an actual vehicle, is investigated under varying combinations of suspension and bush stiffness.

Dynamic Matching System for Radio-Frequency Plasma Generation

Plasma generation systems represent a particularly challenging load for radio-frequency power amplifiers owing to the combination of high operating frequency (e.g., 13.56 MHz) and highly variable load parameters. We introduce a dynamic matching system for inductively coupled plasma (ICP) generation that losslessly maintains near-constant driving point impedance (for low reflected power) across the entire plasma operating range. This new system utilizes a resistance compression network (RCN), an impedance transformation stage, and a specially configured set of plasma drive coils to achieve rapid adjustment to plasma load variations. As compared to conventional matching techniques for plasma systems, the proposed approach has the benefit of relatively low cost and fast response, and does not require any moving components. We describe suitable coil geometries for the proposed system, and treat the design of the RCN and matching stages, including design options and tradeoffs. A prototype system is implemented and its operation is demonstrated with low pressure ICP discharges with O $_{2}$ , C $_{4}$ F $_{8}$ , and SF $_{{6}}$ gases at 13.56 MHz and over the entire plasma operating range of up to 250 W.

Efficient Decoupling Capacitor Placement Based on Driving Point Impedance

With rapidly increasing switching speeds and surge current requirements, placement of local decoupling capacitors is becoming critically important in high-speed low-power designs. In this paper, utilizing the driving-point impedance (viewed from the device pin) as a metric, a new method is presented for the placement of decoupling capacitors in parallel-plate power ground pairs of high-speed circuits. In the proposed approach, instead of using the traditional trial-and-error method to identify an appropriate placement distance, the process is formulated in the form of a transcendental function. The resulting function is solved using Newton–Raphson (N-R) iterations to give a direct solution for the distance. Also, an analytical representation based on Hankel functions for the driving point impedance and its derivatives is developed to speed up the N-R iterations. The proposed method is validated by comparing the results with the full-wave electromagnetic simulations.

Design of High Efficiency Broadband Continuous Class-F Power Amplifier Using Real Frequency Technique With Finite Transmission Zero

In this paper, a new methodology using a distributed ladder structure with finite transmission zero at finite frequencies is proposed for designing a broadband high-efficiency continuous Class-F (CCF) power amplifier (PA). The approach of realizing finite transmission zeros in Richard domain using Real Frequency Technique is first presented. By applying the proposed approach, the characteristics of the driving point impedance (DPI) of the proposed structure can be deduced and obtained in theory. Furthermore, the synthesis methods in Richard domain are extended to synthesize the DPI of the proposed structure. Four types of distributed elements are investigated to synthesize the DPI of the proposed structure. This proposed structure can improve the performance of the CCF PA when the bandwidth approaches an octave as the finite transmission zero can be used to control the second harmonic impedance of the lower frequency which is near the upper frequency of the operation band. To verify the validity of the proposed method, a broadband high-efficiency CCF PA working from 1.15 to 2.2 GHz is designed. Experimental results show that the fabricated PA achieves 11.3–13.7 dB power gain and 40.5–43.2 dBm output power in the operation band. And the PA has also achieved a high-efficiency characteristic of 70%–83% drain efficiency (DE) over the whole operation bandwidth.

Identification of Modeling Boundaries for SSR Studies in Series Compensated Power Networks

Given large-scale power networks with series compensation, the study of subsynchronous resonance (SSR) is a significant challenge, in practice, due to the model complexity and computation burden. To tackle these difficulties, this paper proposes a method to reduce a large-scale system to an equivalent model using a metric called damping sensitivity index. The proposed metric can quantitatively identify the boundaries of the equivalent model that ensure the accurate studies of SSR and reduce the computation burdens greatly. The effectiveness of the method is verified by its application to the SSR investigation of the modified IEEE New England 10-machine 39-bus system and 16-machine 68-bus system. The equivalent models obtained by the proposed method are compared with the original systems in terms of driving point impedances, electrical damping, and transient torques. These results obtained show that the equivalent models from the proposed method can reproduce the SSR dynamics of the original systems with a much shorter computation time.

Multiphysical Study of an Atmospheric Microwave Argon Plasma Jet

In this paper, the multiphysical and frequency-dependent characterization of a microwave argon plasma jet in the GHz range is presented. Three different frequency ranges around 1.3, 2.4, and 3.5GHz are compared using electrical, geometrical, optical, and thermal analyses for different power levels between 2 and 10 W at a constant gas flow. Based on measurements using the large signal S-parameter measuring technique, the plasma base point impedance and microwave conductivity are determined via circuit and finite-element method simulations. Major changes within a small frequency interval are exhibited. Optical measurements are dependent on the geometrical dimension changes of the microwave plasma. It is shown that the geometrical dimensions are strongly dependent on frequency and applied power. These investigated dependencies of the microwave plasma on operation conditions open up new degrees of freedom to match the frequency to the application needs. A description of different applications is given based on the different areas of the measurement results.

The soil plate oscillator: Measuring nonlinear mesoscopic elasticity of granular medium in flexural vibration

The soil plate oscillator apparatus (SPO) consists of two circular flanges (5 inch ID, 8 inch OD, 2.5 inch thick) sandwiching and clamping a thin (1/8 inch) circular elastic acrylic plate. Granular media (soil, masonry sand, glass beads, or even edible granular material) is supported at the bottom by the plate and side walls of the upper flange. A magnetic disk (1 cm) fastened below the plate (on center) is driven by a swept sinusoidal current in a coil placed below the magnet. This electrodynamic SPO, placed in a Wheatstone bridge, was used to measure the on-axis motional electrical impedance Zmot with and without granular loading. Nonlinear tuning curves near resonance exhibit softening with increasing drive amplitude. Measurements of Real{Zmot} and Imag{Zmot} were used to predict the nonlinear mechanical point impedance (Zmech = constant / Zmot) behavior of the SPO system. A lumped element model (granular media and elastic plate system) help determine the mesoscopic nonlinear properties of the granular media alone. Nonlinear tuning curves of the magnet’s acceleration were also measured. A bilinear hysteresis model fits the tuning curve results. See I. T. Perez-Miravete et al., JASA 125, 1302 (2009) for a nonlinear mesoscopic analysis of a flexural bar.

The development of a whole-head human finite-element model for simulation of the transmission of bone-conducted sound.

A whole head finite element model for simulation of bone conducted (BC) sound transmission was developed. The geometry and structures were identified from cryosectional images of a female human head and eight different components were included in the model: cerebrospinal fluid, brain, three layers of bone, soft tissue, eye, and cartilage. The skull bone was modeled as a sandwich structure with an inner and outer layer of cortical bone and soft spongy bone (diploë) in between. The behavior of the finite element model was validated against experimental data of mechanical point impedance, vibration of the cochlear promontories, and transcranial BC sound transmission. The experimental data were obtained in both cadaver heads and live humans. The simulations showed multiple low-frequency resonances where the first was caused by rotation of the head and the second was close in frequency to average resonances obtained in cadaver heads. At higher frequencies, the simulation results of the impedance were within one standard deviation of the average experimental data. The acceleration response at the cochlear promontory was overall lower for the simulations compared with experiments but the overall tendencies were similar. Even if the current model cannot predict results in a specific individual, it can be used for understanding the characteristic of BC sound transmission in general.

Architectures for Shared Control of Vehicle Steering

The allocation of authority between a human driver and an automation system designed to share control with the driver must be managed carefully to ensure safety and driver satisfaction. A driver can tighten grip on a steering wheel, co-contract arm muscles, and change posture to increase authority relative to an automation system that has a finite mechanical impedance. In this paper we develop a system model outfitted with the features required to describe modulating impedance as a means to dynamically allocate authority. We adopt a standard modeling framework, but focus on the description of the driving point impedance of both the driver and the automation system. Haptic feedback from the steering wheel functions both to cue the driver but also to couple the driver biomechanics to the steering and automation system. We also describe a platform designed to support experiments in control sharing with dynamic allocation of authority between two humans, one of them acting as a stand-in for the automation system.

Stability Analysis of Two DimensionalContinuous Filters

The objective of this paper is to formulate an algebraic criterion to analyze stability of two dimensional continuous filters arises in testing a driving point impedance reliability condition in power transmission lines and lumped reactance. Here the stability can be analyzed with the help of complex polynomials. In the proposed scheme which is termed as Sign Pair Criterion (SPC ), Routh-like array is developed and the elements in the first column are utilized to get the stability results. The Routh multiplication rule is applied to find all the elements of the array. This criterion is very convenient and simple compared to other available algebraic procedures for stability analysis.

An empirical study in predicting heavy-weight floor impact sound levels in the 31.5 Hz octave band using driving point impedance

In studies of floor impact noise, increasing attention has been paid to the lower frequency range below 100Hz. Recently, several studies have suggested the importance of including the 31.5Hz octave band in their evaluations. In this band, the floor impact sound is audible but has not been studied sufficiently. The accuracy of two types of so-called ‘impedance’ methods is investigated for the purpose of predicting heavy-weight floor impact sound levels in the 31.5Hz octave band. Although impedance methods are widely used, they are not usually applied to the 31.5Hz octave band. One of the two models is the usual method, in which the sound field of the receiving room is assumed to be diffuse; and the other is a possible variation in which no acoustical mode is assumed in the receiving room. Floor impact sound levels were estimated from driving point impedance levels measured in existing multiple-dwelling buildings and were compared with the measured floor impact sound levels. The results indicate that a hybrid of the two models, with their use depending on the length of the longer side of the receiving room, has the advantage of minimizing the maximum error. However, the hybrid method is unable to improve the general correspondence between measured and calculated values. A simple statistical correction corresponding to the clamping condition of the slab edges is determined to improve the correspondence. A more precise evaluation of the vibration transmission characteristics within a slab would be necessary for further minimization.

Analysis and Performance Improvement of Independent Electric Coupled Resonance WPT System with Impedance Transformer

Wireless power transfer (WPT) technology is expected for the next generation power feeding system, which could supply the power to portable devices without any wires. Compare to the magnetic coupled resonance; a WPT system uses electric coupled resonance could provide a higher position of flexibility. In this paper, the concepts of independent electric coupled resonance type WPT system is investigated by using equivalent circuit including: power transfer function, critical coupling point, frequency splitting and optimum port impedance. After a pair of matching loops are added into source and receive side, the power transfer efficiency could has a great improvement is confirmed by using simulation and experiment.

Fault Location for Transmission Lines with Voltage and Current Measurements at One Bus

Abstract This paper presents a novel fault location method for transmission lines. The proposed method extends an existing method to locate faults by employing voltage and current measurements at one bus, which can be the bus of the faulted line or be far away from the faulted line. The method is applicable if a loop exists that encloses the faulted line, and the bus, of which the voltage is used, and the branch, of which the current is used. The during-fault positive-sequence bus impedance matrix is derived. Then superimposed voltages and currents due to the fault are expressed as a function of fault location and related transfer and driving point impedances. Consequently, the fault location can be evaluated using the obtained measurements. The distributed parameter line model is adopted to consider the shunt capacitances of the line. The proposed method is independent of fault resistance and fault type. Simulation studies have been carried out based on a 27-bus power system, and promising results have been achieved.

On the effect of muscular cocontraction on the 3-D human arm impedance.

Humans have the inherent ability to perform highly dexterous tasks with their arms, involving maintenance of posture, movement, and interaction with the environment. The latter requires the human to control the dynamic characteristics of the upper limb musculoskeletal system. These characteristics are quantitatively represented by inertia, damping, and stiffness, which are measures of mechanical impedance. Many previous studies have shown that arm posture is a dominant factor in determining the end point impedance on a horizontal plane. This paper presents the characterization of the end point impedance of the human arm in 3-D space. Moreover, it models the regulation of the arm impedance with muscle cocontraction. The characterization is made by route of experimental trials where human subjects maintained arm posture while their arms were perturbed by a robot arm. Furthermore, the subjects were asked to control the level of their arm muscles' cocontraction, using visual feedback, in order to investigate the effect of muscle cocontraction on the arm impedance. The results of this study show an anisotropic increase of arm stiffness due to muscle cocontraction. These results could improve our understanding of the human arm biomechanics, as well as provide implications for human motor control-specifically the control of arm impedance through muscle cocontraction.

A Broad-Band Conductively-Loaded Slot Antenna for Pulse Radiation

A slot antenna with a conductive loading profile, which is complementary to the dipole antenna with the Wu-King resistive profile, is derived based on a transmission line model. The drive point impedance of the nonreflecting slot antenna is determined using Babinet's principle. The voltage distribution along the slot arms is shown to be an outward traveling wave with no internal reflection. In addition, the radiated electric field pattern and the efficiency of the nonreflecting slot antenna are discussed. The complementary nature between the Wu-King dipole and nonreflecting slot is numerically verified. The pulse radiation and reception characteristics of the antenna are then demonstrated both numerically and experimentally.

A three-dimensional finite-element model of a human dry skull for bone-conduction hearing.

A three-dimensional finite-element (FE) model of a human dry skull was devised for simulation of human bone-conduction (BC) hearing. Although a dry skull is a simplification of the real complex human skull, such model is valuable for understanding basic BC hearing processes. For validation of the model, the mechanical point impedance of the skull as well as the acceleration of the ipsilateral and contralateral cochlear bone was computed and compared to experimental results. Simulation results showed reasonable consistency between the mechanical point impedance and the experimental measurements when Young's modulus for skull and polyurethane was set to be 7.3 GPa and 1 MPa with 0.01 and 0.1 loss factors at 1 kHz, respectively. Moreover, the acceleration in the medial-lateral direction showed the best correspondence with the published experimental data, whereas the acceleration in the inferior-superior direction showed the largest discrepancy. However, the results were reasonable considering that different geometries were used for the 3D FE skull and the skull used in the published experimental study. The dry skull model is a first step for understanding BC hearing mechanism in a human head and simulation results can be used to predict vibration pattern of the bone surrounding the middle and inner ear during BC stimulation.

A NOVEL ARCHITECTURE OF MAXIMUM POWER POINT TRACKING FOR ULTRA-LOW-POWER BASED HYBRID ENERGY HARVESTER IN UBIQUITOUS DEVICES: A REVIEW

This research work presents a novel architecture of an Ultra-Low-Power (ULP) based Hybrid Energy Harvester (HEH) consisting of multiple input sources such as kinetic, thermal and solar energy, harvested from passive human power. Having multiple ambient sources mitigates limitations caused by single sources especially for bodily-worn applications; however, this results in impedance mismatch among the different integrated sources. To overcome this limitation, the proposed ULP-HEH will use one power management unit with Maximum Power Point Tracking (MPPT) algorithm and impedance matching considerations to efficiently manage and combine power harvested from all three sources to achieve ULP consumptions. Among other crucial sub-modules of the ULP-HEH are its Asynchronous Finite State Machine (AFSM) cum resource sharing arbiter to prioritize and share energy sources for overall power reduction, an efficient rectification scheme for the piezoelectric input, an adaptive feedback for ULP conditioning, Zero-Current Switching (ZCS) for semi-lossless switching, a self-start circuit for low ambient startup, a Boost converter, a Buck regulator, a fuzzy-based micro-battery charger and a de-multiplexer to switch between harvesting or charging capabilities. All of which are implemented for maximum output extraction and minimal losses. This ULP-HEH will be developed in PSPICE software, Verilog coding under Mentor Graphics environment and later to be verified using Field Programmable Gate Array (FPGA) board before the final layout implementation in CMOS 0.13-µm process technology. This battery-less ULP-HEH is expected to deliver 3.0-5.0V of regulated voltage output from low ambient sources of 35 mV at startup. An efficiency of 90% with an output power of 650 µm is expected when all sources are summed. Also, this ULP-HEH is aimed at reducing power consumption to at least twice (

A quest for error factors in predicting heavy weight floor impact sound levels using measured data in existing residential buildings

Abstract A number of datasets regarding the heavy weighted floor impact sound level and the driving point impedance level, i.e., twenty times the common logarithm of driving point impedance at an exciting point, were measured in existing residential buildings before the floor finishing of the excitation room and the ceiling finishing of the receiving room were installed. These data were compared to the calculated values by the impedance method, i.e., a practical method that estimates vibration energy of an excited slab using the driving point impedance at the exciting point as a major factor, as well as those using the Finite Element Method (FEM) models of slabs. Furthermore, correlations between the residual errors and the major dimensions of the receiving rooms were investigated. Two major error factors were found to influence the calculated values by the impedance method. The spectral characteristic of the tire impact source within the 63 Hz band effectively decreased the prediction errors when it was included in the calculation and combined with the FEM models of slabs. The length of the shorter side of the receiving room plan correlated to the residual errors of the receiving rooms having a pair of flat parallel walls. These errors arise from the fact that the receiving points were placed at the central and quarter positions within the wall distance, where the nodes of the horizontal mode exist. It was not possible to identify another dimension of the receiving room that significantly correlates to the residual errors of the prediction.