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The vibration environment in which the vehicle runs is very complex, and impact vibration threatens the ride comfort and structural safety of the vehicle, and at the same time causes premature wear and fatigue damage to the vehicle components. Using TRIZ theory, the reasons for the lack of adaptability of the existing multidimensional frame excitation device are analyzed, and a multidimensional simulation test platform for frames and a supporting multidimensional vibration exciter are innovatively designed, which can achieve real-time position and direction adjustment of the excitation source and meet the needs of specific environments for different vibration effects. The overall frame can be disassembled and reused, which provides more effective data support for the optimization of frame structures of different dimensions. [ABSTRACT FROM AUTHOR]

The vibration environment in which the vehicle runs is very complex, and impact vibration threatens the ride comfort and structural safety of the vehicle, and at the same time causes premature wear and fatigue damage to the vehicle components. Using TRIZ theory, the reasons for the lack of adaptability of the existing multidimensional frame excitation device are analyzed, and a multidimensional simulation test platform for frames and a supporting multidimensional vibration exciter are innovatively designed, which can achieve real-time position and direction adjustment of the excitation source and meet the needs of specific environments for different vibration effects. The overall frame can be disassembled and reused, which provides more effective data support for the optimization of frame structures of different dimensions. [ABSTRACT FROM AUTHOR]

Accurate and timely fault diagnosis of the rotating rectifier for a wound-rotor synchronous starter/generator is of great importance to improve system reliability. In the generation mode of the system, there is one idle stator winding of the main exciter. The terminal voltage characteristic of the idle stator winding is analyzed, and a novel fault diagnosis method for the rotating rectifier in the generation mode of the system is proposed. In this method, two feature voltages, namely, the maximum peak voltage and any other peak voltage of the idle stator winding terminal voltage are extracted through voltage sequence reconstruction to calculate the feature ratio for fault detection. The corresponding rotor position obtained by an inherent position sensor where the maximum peak voltage occurs is collected to determine the faulty diode location. The experimental results verify the feasibility and effectiveness of the proposed fault diagnosis method.

Weak grid scenarios and low-inertia systems are emerging issues in power systems, which could lead to voltage and frequency instabilities. Synchronous Condensers (SynCons) have recently drawn renewed attention as a promising solution to provide system strength and inertia support. Even though the exciter control of SynCons is a well-established technology, further developments are required to guarantee the stability of post-fault operations, in particular, in weak grids. This paper proposes a data-driven approach for designing higher-order optimized exciter controllers to meet this requirement. A pseudo-random binary sequence (PRBS)-based system identification method is used to obtain frequency response data of the power system, from the exciter point of view, which is then fed into the proposed optimal control design procedure. The proposed exciter controller is tested for voltage ride-through and fault scenarios in a single machine infinite bus (SMIB) case and the IEEE 39-bus test system to assess its performance compared to the conventional AC1A exciter controller. The results obtained through simulation tests carried out using the PSCAD/EMTDC software verify that the proposed exciter controller guarantees the post-fault stability in both strong and weak grids.

A double electrical excitation synchronous generator (DEESG) with an embedded brushless exciter is proposed to achieve brushless excitation for a brush excitation electrical excitation synchronous generator (EESG). A set of extra stator excitation windings is placed in the stator slots with armature coils to generate a static magnetic field. There are two sets of windings on the rotor: pulsating excitation winding (Wp) and main excitation winding (WF). The winding direction of the coils of Wp and WF on the same rotor-pole-body is the same. The AC voltage of Wp which is induced by static magnetic field provides dc excitation current for WF by diodes. Both currents in the coils of the Wp and WF generate the rotor excitation flux which induces voltage in the armature coils. In this study, the operating principle is analyzed theoretically. The no-load and load characteristics are studied using Maxwell. The influence of the novel winding structure on the output voltage when the load varies is also analyzed. The voltage regulation rate of DEESG is reduced because the rotor excitation currents can be increased with armature current. A 1.5 kVA prototype is fabricated for experiment. The measured results agree well with the theoretical and FE-predicted results.

This article proposes a rotor position estimation method for brushless electrically excited synchronous starter/generator (BEESSG) at low speed region. Based on the multistage characteristics of BEESSG, two high frequency pulsating voltages with different frequencies are injected into phase $\alpha$ and phase $\beta$ of stator of the main machine simultaneously. The rotor position is estimated by the high frequency induced signals extracted from the stator windings of the main exciter through a position estimator. Low-pass filters are replaced by an auxiliary square wave sampling method to demodulate the rotor position from high frequency induced signals. Due to the amplitude unbalance of demodulated position related signals. A novel first quadrant definite integral method is proposed in this article for position compensation. Furthermore, the effectiveness and feasibility of the proposed method are verified by experimental results.

In this article, an exciter–quadrature–repeater transmitter pad is proposed in order to achieve high lateral misalignment tolerance and low leakage flux emission in electric vehicle wireless charging applications. In the proposed WPT system, a single half-bridge inverter unit is needed to energize the exciter coil, which is magnetically coupled to two larger quadrature repeater coils. The currents in the two repeater coils naturally adjust based on the lateral misalignment of the receiver pad to reduce the leakage flux density around the charging zone. The system can maintain zero phase shift between excitation voltage and current and achieve constant current charging conditions with fixed compensation capacitors in the ±150-mm lateral misalignment range. In order to verify the attributes of the proposed wireless power transfer (WPT) system, a 3-kW experiment setup with a 200-mm vertical gap was built and compared to a three-coil WPT system, which consists of a small transmitter coil, a single large repeater coil, and a receiver coil. According to the experiment results, even under extreme 150-mm lateral misalignment, the proposed WPT system has 90.7% coil-to-coil transmission efficiency. Furthermore, it achieves a 30% reduction of leakage flux density compared to the three-coil system in the 150-mm lateral misalignment case.

Fault detection of a rotating rectifier for a wound-rotor synchronous starter/generator (WRSSG) without a rotor position sensor in the stationary state is necessary for a successful engine start. Based on high-frequency (HF) voltage injection, a novel fault detection method of the rotating rectifier for the WRSSG in the stationary state is proposed. The rotating HF voltage is imposed on the stator windings of the main machine, and the HF feature current signal extracted on the stator windings of the main exciter is used for fault detection. In this article, the HF current signal in the main exciter with the rotating rectifier under different working conditions is analyzed first. To obtain the HF response current on the stator windings of the main exciter, the HF model of the WRSSG is analyzed. Through the Fourier series, the HF feature current signal together with fault detection is achieved. Compared with the existing fault detection methods, the proposed method shows no dependency on the rotor position information. Experimental results verify the feasibility and effectiveness of this method.

The present paper describes a theoretical and an experimental investigation of Clamped-Simply-Clamped-Simply supported isotropic rectangular plates subject to a large amplitudes forced transverse vibration. The theoretical model is based on Lagrange equations and the harmonic balance method which is used to obtain the non-linear algebraic equation of the problem. To examine our results, a test rig is designed and made. Furthermore, an electrodynamic exciter is used to provide the transverse harmonic vibrations, whereas an accelerometer measures the displacements. The approximate analytical solutions are obtained, and the experimental measurements are discussed and compared which are highlight the nonlinear hardening resonance.

Purpose Due to the installation of the new, more powerful gearbox and the dismantling of the exciter machine, the vibration characteristics of the shaft train will be changed. Therefore, it is necessary to reassess the shaft train. It is to be investigated if the shaft train of the compressor meets the general requirements for bending and torsional vibrations and can be safely operated within the electrical network. The purpose of this paper is to show the necessary alignment of modification, calculation and measurement in such a project.. Design/methodology/approach After some modification work on the shaft train of an air compressor, it was necessary to do some engineering calculations regarding the bending natural and torsional natural frequencies and their mode shapes. The correctness of the calculated values was proven by vibration measurements performed at the shaft train in operation. Findings It can be concluded that the change and replacement of rotating equipment in a shaft train never should be done without any engineering calculations in advance and measurements after the component modification. Most important is that the calculation results have to be compared with the measurement results for verifying the calculation assumptions. In the case described above, one can see that theory and practice match well. In addition to this, the very low damping of torsional vibrations is proved again, which can be a significant problem in some situations. Originality/value Also, today one can find torsional vibration measurements of rotating machines, including frequency, magnitude and damping factor, very seldom. Especially for smaller machines, there are no real comparisons between calculation and measurement are usual. This paper shows that an alignment between theoretical and practical approaches is necessary to avoid operational problems for rotating machines.

The literature contains evidence that the membrane potential of a biological neuron exhibits several behaviors such as quiescent, spiking, bursting and chaotic states when the external excitation current is adjusted. This paper proposes a model of the photosensitive neuron and the thermosensitive one driven simultaneously, by optical signals and heat acting as the external exciter current. The analysis of the equilibrium points and the stability of the model is carried out. It is shown that the temperature variation produced by the thermistor modifies the number and the nature of the equilibrium points of the system. This temperature also induces a Hopf bifurcation showing that the neuron can go from a state of rest to an oscillatory state and vice versa. The excitation current produced by the phototube and the thermistor makes it possible to generate behaviors already observed in the literature (biological characteristics of the neuron) and complex phenomena. These complex phenomena are among others, bifurcations such as period-doubling, reverse period-doubling, intermittence (crisis) and antimonotonicity. Finally, an on-board system implementation of this neuron model is presented using microcontroller technology. It can be seen that these special behaviors can be easily produced in their actual electrical nature. This constitutes an important tool that can be applied in biomedical technology for the design of artificial neurons.

Serving as a prerequisite to power system dynamic state estimation, the observability analysis of a power system dynamic model has recently attracted the attention of many power engineers. However, because this model is typically nonlinear and large-scale, the analysis of its observability is a challenge to the traditional derivative-based methods. Indeed, the linear-approximation-based approach may provide unreliable results while the nonlinear-technique-based approach inevitably faces extremely complicated derivations. Furthermore, because power systems are intrinsically stochastic, the traditional deterministic approaches may lead to inaccurate observability analyses. Facing these challenges, we propose a novel polynomial-chaos-based derivative-free observability analysis approach that not only is free of any linear approximations, but also accounts for the stochasticity of the dynamic model while bringing a low implementation complexity. Furthermore, this approach enables us to quantify the degree of observability of a stochastic model, what conventional deterministic methods cannot do. The excellent performance of the proposed method has been demonstrated by performing extensive simulations using a synchronous generator model with IEEE-DC1A exciter and the TGOV1 turbine governor.

The brushless excitation structure characteristics of the aviation wound-rotor synchronous starter/generator (WRSSG) put forward the requirement on the brushless exciter (BE) model that both the stator and rotor windings can be interfaced with the external circuit directly. In this paper, a double-side variable-parameter voltage-behind-reactance (DS-VP-VBR) model of the BE considering magnetic saturation was established firstly to realize the direct connection between the stator and rotor windings with external circuits. Then, a double-side constant-parameter VBR (DS-CP-VBR) model with completely decoupled RL circuit was developed through the algebraic transformation and numerical approximation from the DS-VP-VBR model. In order to further improve the model accuracy, the leakage inductance variation of the stator and rotor windings were also considered. Computer studies under steady-state and transient operating conditions verified the validity and accuracy of the proposed BE DS-VBR models.

The excitation system with a multi-phase annular brushless exciter (MPABE) is widely used in large-capacity nuclear power plants. It is of great significance to realize a reliable protection of the exciter for safe operation. Since the MPABE is adopted with rotary armature structure, the rotor winding short-circuit (RWSC) fault is very difficult to be diagnosed directly. However, it is an effective way to realize fault diagnosis through the characteristics reflected in the stator field winding. In this paper, based on the mutual induction relationship between stator current and rotor current, detailed theoretical analysis of the RWSC fault is conducted and the harmonic characteristics of the stator field current are obtained. Then, related experiments and simulations are carried out, verifying the correctness of the theoretical analysis. Finally, a diagnosis method based on the transient harmonic characteristics of the stator field current is proposed and its sensitivity is also analyzed. The diagnosis method proposed in this paper is simple and feasible, which helps to improve the safety and reliability of the MPABE system in nuclear power plants.

A hybrid excitation brushless dc generator (HEBLDCG) system, consisting of a main generator (MG) and an integrated exciter, is proposed and developed in this article. The excitation sources types of the stand-alone generation system and corresponding characteristics of the sources types are summarized. In the target HEBLDCG system, the integrated exciter shares a flux path with the permanent magnet machine part (PMMP), which is a part of the MG, without extracting power from the output terminal or sacrificing the efficiency of the generation system. It is the reactive power in the PMMP that leads to these aforementioned advantages. Also, the basic design flowchart of the exciter is expounded upon, and the values of some parameters are discussed. The designed exciter meets the requirements of the field power of the MG for the whole speed range and under varying load conditions. Based on the well-designed exciter, the electromagnetic performance is analyzed in terms of its open-circuit and load performance. Furthermore, the reason why the output power of the MG is not reduced by the integrated exciter is analyzed. Finally, open-circuit and load experiments for the exciter are conducted, and the proposed excitation method is found appropriate for the HEBLDCG system.

This article introduces a self-excitation technology for field wound synchronous machines (FWSMs) to eliminate conventional components required by brushless and brushed static excitation systems. This technology is based on the utilization of pre-existing airgap flux harmonics, so no exciter or brush is required. The energy of these airgap harmonics at the slotting frequency is captured using rotor-mounted harvesting coils. A power electronic converter is then used to rectify the induced harvesting coil voltage and regulate the field winding current of the FWSM. Simulation results are presented showing the efficacy of the proposed method for a prototype FWSM under various loading conditions. For demonstration, a full-scale 5.4-MVA synchronous generator is used for design and validation.

The order model of synchronous generator plays very important roles of determine the accuracy of power system dynamic study. This paper presents the simulation and analysis of the sixth order model of synchronous generator for power system dynamic study by using Simulink. The mathematical model of stream turbine governor and exciter are also considered in this paper. The presented method is tested on the single machine infinite bus system.

A harmonic excitation brushless synchronous machine has higher power density compared with the traditional aerial three-stage generator due to removing the axial exciter and is suitable for use as an integrated starting-generator (ISG). However, the field current cannot always be generated in the field windings at different rotor positions in the starting mode. A new excitation scheme employing double three-phase phase orthogonal zero-sequence armature currents is proposed in this article. Harmonic electromotive forces and field current can be produced by the zero-sequence rotating excitation magnetic field and almost has no relationship with the rotor positions. In addition, in order to obtain a constant field current during the starting process, a control method of the generated field current is also presented. The rotating speed and field intensity of the zero-sequence excitation magnetomotive forces are both feedback controlled by the zero-sequence current in the whole starting process. Comparing with the original harmonic excitation machine, a higher and more stable field current can be generated in the proposed ISG whenever the rotor is at any position or at a low speed. The prototype machine is manufactured and experiments are carried out together with the excitation control method to verify the effectiveness of the theoretical and finite element analysis results.

Brushless structure is beneficial for air-core compensated pulsed alternator (ACPA) because its field current and rotation speed are too large for the slip rings and carbon brushes. To achieve the brushless structure, a cascaded brushless self-excited ACPA (CBSACPA), which consists of an exciter and a generator in cascade, is proposed, in this article. The exciter and generator have a common rotor. A novel squirrel-cage rotor winding (SCRW), which can eliminate the end winding compared with conventional wound rotor winding (WRW), is proposed to simplify the rotor structure and improve the performance. First, the structure of the CBSACPA with the SCRW is introduced. Second, the operation principles of the machine are elaborated. Third, the dynamic mathematical model is presented. Fourth, the operation principles are demonstrated by the finite-element method. In addition, the performance of the SCRW is compared with the WRW as well. Finally, a prototype of CBSACPA is developed and tested to validate the analyses and simulations. In conclusion, this study gives detailed introduction, analyses, and validation about the CBSACPA, which provides a new solution to achieve a brushless structure for the ACPA.

In this article, an online approach for joint parameter estimation of the exciter and Synchronous Generator (SG) is proposed. It only utilizes the Phasor Measurement Unit (PMU) based measurements, which can be obtained at the SG's terminal and does not require field measurements (as in brushless exciters). Compared to existing joint estimation approaches, the proposed work includes multiple aspects to put forward a pragmatic estimation framework. Firstly, the unobservable erroneous initial states are duly considered by utilizing the proposed Augmented Parameter Vector (APV). It is an essential feature in practical scenarios as an accurate representation of a dynamic system entails knowledge of true initial states and parameters. Secondly, suitable models of SG and exciter necessitate the inclusion of saturation characteristics, which is also considered in present work. Further, the estimation procedure is independent of multiple pre-tuned parameters, as such dependence may lead to tedious implementation and inaccurate estimates. Additionally, Wavelet denoising is used to improve the parameter estimation accuracy by pre-processing the noisy measurements prior to estimation. Real-Time Digital Simulator (RTDS) based simulation results, considering noise and measurement rate analogous to commercial synchrophasors, demonstrate the proposed approach's improved accuracy.

Power system economical operation consists of two aspects: active power regulation and reactive power dispatch. This multiobjective optimization problem is solved in this p ap er as two subproblems: P- and Q-problems. The solution is applied to an EEE 14-bus system using Genetic Algorithm (GA). Additionally, An exciter system lead-lag controller and feedback compensator parameters are also optimally selected using GA.

A magnetization system with active compensation of unbalanced magnetic pull for synchronous machines with rotating exciters is demonstrated. The system used switched power electronics and a digital control system to control the currents in four rotor pole groups, each consisting of 3 poles. It was mounted on the shaft of a synchronous machine, providing an interface between a permanent magnet outer-pole brushless exciter and the segmented field winding. Measurements of magnetic flux density on each pole face and current control made it possible to control the airgap magnetic flux density to balance the machine magnetically, thus removing flux density space harmonics in the airgap and also the unbalanced magnetic pull. The construction of the system is presented along with results from experiments and simulations. Tests were performed with the stator winding both in series and with two parallel circuits. Approximately $\mathbf {80\%}$ reduction of static forces and $\mathbf {60\%}$ reduction of dynamic forces between the stator and rotor were observed when the system was running.

A new variant for construction of a exciter of the Н01 mode of a circular metal waveguide using a smooth transition from a single-mode rectangular metal waveguide to a circular multimode waveguide is proposed and analyzed. Electrodynamic simulation and optimization of parameters of the transition are performed with the aid of the finite-element method and finite-difference method in the time domain. It is shown that the proposed device with a relatively small length provides low reflection loss and conversion to the other modes of the circular waveguide in a wider frequency band in comparison with alternative transducers.

This paper describes, the application of transient energy function and some laws of theoretical mechanics necessary to the problem of analysing Co-ordinated stabilizer in a multimachine power system. The co-ordinated stabilizing inputs for the exciter and governer loops to improve transient stability in the power system are defined. The different energies in the power system are analysed. If the power system is asymptotically stable in the first swing cycle, the rate of change of total transient energy must tend to zero. This constraint is accomplised by the proposed stabilizer. The stabilizer is designed on the base of balancing its forces with the necessary forces to damp swings of generator rotors. The effectiveness of the proposed stabilizer is demonstrated by applying it to a generating station in a 10-generator and 19-bus power system, which represents the reduced Egyptian Unified Network.

Non-Directional Beacon today remain effective ground-based radio navigation devices. Non-Directional Beacon together with on-board equipment – automatic radio compass allow aircraft crews to solve complex air navigation problems. Non-Directional Beacon and automatic radio compass system, which is a goniometric radio navigation system of the radio compass type, provides aircraft crews with the ability to measure the heading angle of the radio station and use this data during en-route flight, aircraft withdrawal to the airfield area and during landing approach. The current state of most ground-based radio-technical navigation aids, which include Non-Directional Beacon, is characterized by their unsatisfactory physical and moral condition, limited element base for repairs and requires their prompt modernization. One of the prority task of modernization of Non-Directional Beacon is the task of implementing digital frequency synthesis of excitation signals of the power amplifier of a radio transmitter of Non-Directional Beacon in a wide range of low and medium frequencies with a sufficiently small step (100 Hz) of the grid of operating frequencies. Taking this into account, the work substantiates one of the ways of constructing the Non-Directional Beacon exciter. It includes a digital synthesizer of frequencies of the decameter wavelength range and a converter of the synthesizer's output frequencies to the operating range of the Non-Directional Beacon exciter. A scheme for constructing a synthesizer based on phase automatic tuning of the frequency of a voltage-controlled oscillator to the frequency of a quartz reference oscillator is proposed. The algorithms for obtaining a fractional – variable frequency division factor and a circuit for constructing a pulse-phase detector in a ring of phase automatic frequency control of a voltage-controlled generator are substantiated.

The paper presents a case study pertaining to the analysis of factors affecting the measurement uncertainty in primary calibration of accelerometers at lower frequencies in range of 0.1 to 40 Hz using low-frequency primary vibration calibration standard realized at CSIR-National Physical Laboratory, India. The potential high accuracy and precision in measurement are achieved with a long-stroke exciter, APS 113AB having lowest transverse motion and by data acquisition at a high sampling rate and digital band pass filtering. The study evaluates the measurement uncertainty in accelerometer complex sensitivity including phase determination using a laser interferometer and an optical encoder. A comparison of the results of a laser interferometer and an optical encoder is presented. The measurement uncertainty in the sensitivity determination and phase measurements using both these approaches is validated from the results of participation in an international key comparison exercise.

Permanent magnet generator is one of the key components of a three-stage electrically excited brushless synchronous motor, with a main function to provide excitation power for the main exciter and driving power for the controller. In order to improve the reliability and safety of the operation of the three-stage electrically excited brushless synchronous motor, the permanent magnet generator is required to provide sufficient power under all operating conditions and to have low short-circuit current when its own short-circuit fault occurs, so that the generator will not be burnt out due to overheating. Thus, power characteristic and high impedance characteristic are the key goals of designing a permanent magnet generator. In this paper, the fractional slot concentrated winding was adopted to calculate and analyze the electromagnetic properties of permanent magnet generators with different rotor structures, and the optimal design was obtained. A prototype was manufactured to conduct related experiments on the electromagnetic properties. The results demonstrated that the experimental data are basically consistent with the simulation data, and the permanent magnet generator can meet the design requirements for power and high impedance characteristics, with a high power density.