Generator Rotor Research Articles

Spectrum characteristics and temperature measurement error of FBG sensor based on rotor temperature monitoring system

For real-time temperature monitoring of a generator or electric motor rotor, the effects of rotation on the reflection spectrum of a polyimide-coated Fibre Bragg Grating (FBG) were analyzed using formulas. The measurement error resulting from the low-speed operation was evaluated, combined with the finite element method. Secondly, the key design of the FBG sensors and the mating part of the fiber optic rotary joint (FORJ) were investigated. The temperature of a rotating shaft was monitored to test the reliability of the measurement system. With a resolution of 0.1℃, the system was able to achieve an error of 0.5℃ over a range of 30-180℃. Finally, the critical conditions for the application of polyimide-coated and metal-coated FBGs were discussed. The results show that the variation of the center wavelength is more sensitive to the radius of the small-sized rotor, and the rotation speed of the large-sized rotor. It is at higher speeds that the thickness of the coating has a more pronounced effect on error, demonstrating that the accuracy of FBGs used in high-speed rotors could be rapidly improved by reducing the thickness of the metal coating. The reported results provide a basis for the thermal monitoring performance of FBG sensors during rotation.

Analysis of Performance Improvement of Passenger Car Synchronous Homopolar Generator with the Addition of Ferrite Magnets

Electric machines with hybrid excitation have increased torque density while maintaining a wide range of speed control. This article presents the results of the optimal design of a synchronous homopolar generator (SHG) with ferrite magnets on the rotor and excitation winding on the stator for passenger cars. The use of ferrite magnets on the rotor of a synchronous homopolar generator makes it possible to use the stator surface more efficiently, which in turn increases energy efficiency and reduces the dimensions of the generator. At the same time, the excitation winding on the stator provides a reliable brushless design and the ability to control the excitation flux. The problem of long-time calculation of the three-dimensional SHG structure, which is especially relevant when using multi-iterative computer optimization, is solved by using the computationally efficient Nelder-Mead method and a simplified SHG model using two-dimensional finite element analysis. It is also clear that the low torque ripple of SHG with ferrite magnets with two stator-rotor stack combinations (SRSC) is largely provided by the fact that the torque ripples of individual SRSCs are in antiphase. The problem of considering the magnetic properties of magnetic core sections made of structural low-carbon steel is discussed. It has been found that with an increase in both the saturation level of the magnetic circuit and the magnetomotive force (MMF) of the SHG excitation winding, resistance to irreversible demagnetization of ferrite magnets on the rotor can be increased by increasing their height. In addition, it is shown that there is a significant increase in performance when using the hybrid excitation, in comparison with the conventional SHG design without magnets.

Erosion-damage-induced vibration response of aero-gas generator rotor system

When a turboshaft engine operates in harsh environments such as deserts, plateaus, and coastal areas, the erosion damage to compressor blades leads to uneven mass distribution of the blade disk of the gas generator and further induces unbalance fault vibration of the rotor system, which seriously endangers helicopter flight safety and mission execution. The vibration characteristics of the rotor system of the gas generator of an aero-turboshaft engine under blade erosion damage are studied innovatively in this paper. The theoretical formula for the blade erosion damage depth is derived. The key parameters for the calculation of the erosion damage to the blades are obtained by combining the particle impact velocity test, Ti-6Al-4 V alloy erosion wear test, and finite element analysis. A new data extraction method for erosion damage based on distribution characteristics and the sparseness–denseness path (DC-SP) is proposed. The unbalance fault mechanism of the rotor system caused by erosion damage is revealed. Using a turboshaft engine as an example, a dynamic model of the rotor system of a gas generator is developed. Unbalance load samples caused by erosion damage are applied, and the whirl trajectory and vibration spectrum characteristics of the rotor system analyzed. The results show that the unbalance magnitude of 1-stage and 3-stage rotor blades caused by erosion damage is 2.33 times and 1.22 times that of 2-stage rotor blades, respectively. The vibration response of the supporting position of the rotor changes with the unbalance phase difference of the rotor blade disk. The vibration amplitude of the supporting position is the lowest when the unbalance phase difference is 0°-180°-180° and is the highest when the unbalance phase difference is 0°-0°-0°. At design speed, the vibration amplitude fluctuation range of the left side of the supporting position is concentrated, whereas that of the right side is large. When the unbalance magnitude increases from 20 to 120 g·mm, the vibration amplitudes of the left and right sides of the supporting position increases by 97% and 263%, respectively.

Effect of Generator Rotor Radial Deviation on the Unbalanced Magnetic Pull of 1000 MW Hydro-Generator Unit

The 1000 MW hydro-generator unit has huge geometrical dimensions and requires high installation accuracy. The control of its installation deviation will directly affect the installation quality and operational performance of the unit and the rotor eccentricity is one of the core problems faced in the installation and operation of the giant hydro-generator unit. This paper presents a method to calculate the asymmetric magnetic field by means of the transient finite element calculation to reveal the effect of the generator rotor radial deviation on the unbalanced magnetic pull of the unit. The effects of rotor dynamic eccentricity on the magnetic field are analyzed in the time and frequency domains, respectively. The results show that both the DC component and the key harmonic component of the unbalanced magnetic pull increase with the increase of the eccentricity value, and this variation relationship is nearly linear. when the eccentricity is no more than 0.15 mm, the unbalanced magnetic pull caused by the rotor eccentricity is calculated to be small, which is acceptable. The conclusions of this investigation can help to straighten out the requirements and standards for the installation deviation control of the large hydro-generator units.

Effect of Unbalanced Magnetic Pull of Generator Rotor on the Dynamic Characteristics of a Pump—Turbine Rotor System

In pumped storage units, the rotor-bearing electromagnetic system is under the joint influence of hydraulics, mechanics, and electromagnetics, and the mechanism of unit vibration problems is very complex to investigate. ANSYS software is used to establish a three-dimensional model of a pumped storage power plant’s rotor-bearing electromagnetic system, and the stiffness coefficient of the unbalanced magnetic traction forces is calculated using the Fourier series of the magnetic conductivity of the air gap. This shows that the nonequilibrium magnetic attraction increases non-linearly with increasing excitation current and eccentricity of the rotor. At each order, the critical velocity of the rotor system increases as the stiffness factor of the bearing increases, with the greatest increase in critical velocity at the third and fourth orders. In the first-order mode-oscillation pattern, the unbalanced magnetic attraction has an effect on the intrinsic frequency of the transverse oscillation, with a reduction in the amplitude of the intrinsic frequency by 34.65%. Axial and transverse modal vibrations manifest themselves as upward and downward motions and transverse oscillations in different portions of the rotor system, respectively, whereas torsional modal vibrations manifest as a radial broadening or reduction in the generator rotor, runner, and coupling portions of the rotor system. The results of the study provide a theoretical foundation and a computational method for the dynamic analysis and design of the rotor system of pumped storage power stations.

Microgrid-Based Wind and Solar Power Generation on Moon and Mars

This letter proposes a DC microgrid for sustainable power generation on the Mars/Moon for a human inhabitation base. The proposed microgrid includes: (i) A wind turbine (WT) system with a dual rotor generator (DRG) whose output is rectified using a passive rectification state and connected to the microgrid common DC bus with a fixed voltage using a DC-DC converter. (ii) Solar panels that use Passive Emitter and Rear Cell (PERC) material suitable for in-space application whose data are available to the authors; the solar panels are connected to the DC bus using a DC-DC converter. (iii) Battery energy storage system (BESS) that uses a modified lithium-ion material that is space-tested and connects to the DC bus via a bidirectional DC-DC converter. The microgrid feeds three loads, a constant DC load, a 3-phase AC load, and a Mars Rover charger station. A maximum power point tracking (MPPT) controller is proposed for the WT and solar system while a supervisory controller is developed that manages the power flow strategy from the sources to the loads based on the BESS state of charge (SoC). The letter discusses conditions of the Mars/Moon, the challenges for sustained power generation and provides simulation results for the steady-state and transients analyses.

Application of Improved Process Neural Network Based on the Fireworks Algorithm in the Temperature-Rise Predictions of a Large Generator Rotor

Building an effective algorithm model for large key power equipment has very important research significance and application value. Aiming at the typical operating state characteristics of large generators and taking the temperature changes as the main research indicators, the improved fireworks algorithm was used to optimize the process neural network, and the key data characteristics were studied based on the machine experiment and actual operation data of a 300 MW generator so as to find the variation and development trends of the maximum temperature rise caused by negative-sequence current. Furthermore, the effectiveness of the neural network model suitable for large generators established in this paper was verified by test functions and experiments. On this basis, the calculation method was applied to different working conditions, component materials, and heating positions of the generator. Moreover, the temperature-rise prediction results of the structural components for the generator rotor were obtained, and the optimization scheme of the slot wedge material given, which provide a reference for temperature-rise research and the selection of component materials for large generators.

A Review on Rotary Generators of Hydrodynamic Cavitation for Wastewater Treatment and Enhancement of Anaerobic Digestion Process

The issue of ever-increasing amounts of waste activated sludge (WAS) produced from biological wastewater treatment plants (WWTPs) is pointed out. WAS can be effectively reduced in the anaerobic digestion (AD) process, where methanogens break down organic matter and simultaneously produce biogas in the absence of oxygen, mainly methane and CO2. Biomethane can then be effectively used in gas turbines to produce electricity and power a part of WWTPs. Hydrodynamic cavitation (HC) has been identified as a potential technique that can improve the AD process and enhance biogas yield. Rotary generators of hydrodynamic cavitation (RGHCs) that have gained considerable popularity due to their promising results and scalability are presented. Operation, their underlying mechanisms, parameters for performance evaluation, and their division based on geometry of cavitation generation units (CGUs) are presented. Their current use in the field of wastewater treatment is presented, with the focus on WAS pre/treatment. In addition, comparison of achieved results with RGHCs relevant to the enhancement of AD process is presented.

Digitalization and hydroinformatics

Digitalization and hydroinformatics

Design of intelligent nonlinear robust controller for hydro-turbine governing system based on state-dynamic-measurement hybrid feedback linearization method

Due to the stochastic grid loads and intermittent renewable energy sources in today’s power grid, hydro-generator and grid system stability is increasingly dependent on the hydro-turbine governing system (HTGS). For the HTGS with external disturbances and system uncertainties, an intelligent nonlinear robust controller (INRC) based on state-dynamic-measurement feedback linearization (SDMFL) is proposed to enhance the HTGS’s control performance in this paper. This strategy establishes a dynamic output function including actuator displacement, generator rotor angle, and turbine parameters. The relationship between dynamic output and control input is derived based on this function to establish the corresponding linear state-space model. Then, the mixed H2/H∞ robust controller based on the linear model is designed to suppress the effects of external disturbances and system uncertainties on the system performance. In addition, the controller performance is optimized by levy flight and chaos theory-based gravitational search algorithm (LCGSA), resulting in the INRC. Simulations are performed in MATLAB, and the results are compared with the nonlinear robust controller (NRC) and PID controller. The results show that the proposed controller INRC improves the control performance of nonlinear HTGS with smaller overshoot and shorter adjustment time in all cases.

A review of opposition-based whale optimization algorithm and whale optimization algorithm tuned power system stabilizer for multimachine stability

This research aims to improve the stability of power systems using a power stabilizer. Various methods were used to finetune the conventional Power System Stabilizer (PSS) with a lead-lag compensator by minimizing the integral absolute error of speed deviations of generator rotors. To evaluate the performance of the various methods, different timedomain simulation test cases were conducted and the results were compared with the performance of the Oppositional Whale Optimization Algorithm-based Power System Stabilizer (OWOA-based PSS), Whale Optimization Algorithm-based Power System Stabilizer (WOA-based PSS), and the conventional PSS. The obtained results show that the OWOA-based PSS is more efficient in power oscillation damping than the other methods, including the WOA-based PSS. Overall, the OWOA-based PSS can be considered as a potential solution to enhance the stability of power systems by mitigating power oscillations in generator rotors. However, further studies and experiments may be required to validate all methods and compare them to ensure their effectiveness and efficiency.

Researching localization of vertical axis wind generators

The paper analyses the economic efficiency of using wind power plants in mountainous areas and small residential areas as well as the results of using vertical axis wind devices in areas with low-speed winds. So it became possible to obtain the necessary electrical energy in the less windy regions of Uzbekistan by using vertical axis wind generators. In recent years the demand for electricity is increasing gradually as a result of the sharp growth of direct production enterprises and population consumption. This demand can be compensated by using not only traditional energy sources but also non-traditional energy sources. The use of wind energy is to a certain extent the basis of energy production. Nurato district of Navoi region of Uzbekistan was selected as an object. The problems of saving and shortage of electric energy will be avoided by using the vertical axis wind generator in the regions. By moving the rotor of the wind generator the wind energy is converted into mechanical energy, which generates electrical energy through the generator. Electric power from the generator is provided by a controller that serves to monitor the charge level of the accumulator and is sent to the accumulator through the controller.

Methods for improving the efficiency of a wind power plant and reliable estimation of output control parameters and disturbances

A method for controlling a wind power plant based on the use of the optimization model that takes account of the drive vibration loading under different operating modes of the power unit is validated. The transfer functions of the rotor systems dynamic links are proposed, taking account of the influence of wind speed and electrical load, the block diagram of the control system and the transient process graph of the angular velocity regulating of the installation generator rotor. To ensure the reliability of the output control parameters and disturbing influences estimation, the determining method substantiation of the dynamic links correlation coefficients for the wind power plant rotor system is performed. These coefficients are necessary to develop models of the system dynamic behavior used in the modification of the wind power plant automated control in order to reduce the vibrations of all rotor systems elements under different operating modes of the power unit that will improve the reliability of modern wind turbines. The correlation function parameters to determine the correlation dependences for the measured values of wind speed and electrical load are found. Formulas are derived for determining the spectral density of input and output random processes at changing wind speed and electrical load, as well as the mutual spectral density of input and output random processes for dynamic links of rotor systems (rotary blades, rotor, generator, gearbox) based on the block diagram of the entire process in order to determine the correlation degree of transfer functions. The analysis of the input and output signals of the transfer functions with respect to their coherence is carried out from a correlation coefficients calculation of the rotor systems dynamic links. This makes it possible to describe the transfer function within the framework of the vibration fields analysis for the unit as a whole. Keywords wind power plant, control, rotor system, vibration, correlation coefficient

Research on fault monitoring system for collector ring and carbon brush of generator rotor

The operating status of the generator rotor's collector ring and carbon brush determines the safe and stable operation of the generator. It is critical to promptly detect and handle any abnormalities or faults in the collector ring and carbon brush to prevent accidents from expanding. At present, the status monitoring of the collector ring and carbon brush mainly relies on manual inspection, which has low efficiency and cannot discover faults in real-time. This article studies the establishment of a fault monitoring system for collector ring and carbon brush of the generator rotor. Through real-time collection and analysis of arc light, temperature, and electrical data, abnormalities and faults can be detected and alerted in a timely manner. This system can improve the accuracy and effectiveness of monitoring, and ensures the safe operation of the generator.

Design and performance analysis of opposition-based whale optimization algorithm tuned power system stabilizer for multimachine stability

A novel Opposition-based Whale Optimization Algorithm (OWOA) is utilized to build a power stabilizer and increase multimachine stability. A Conventional Power System Stabilizer (CPSS) with a lead-lag compensator is employed, and OWOA fine-tunes its settings using an objective function that minimizes the integral absolute error of speed deviations of generator rotors. Various time-domain simulations were performed to validate the superior performance of the proposed Power System Stabilizers (PSS). Furthermore, the performance of the proposed PSS is compared to a Whale Optimization Algorithm (WOA)-based PSS and a conventional PSS. The obtained results demonstrate the effective performance of the proposed OWOA-based PSS for power oscillation damping.

Energy-harvesting Efficiency Analysis of Ocean Currents: Proposing a Flow-induced Vibration Power-Generation System with Linear Generator Damping

Bai, X.; Sun, M.; Niu, J.J.; Sun, H., and Sun, L.P., 2023. Energy-harvesting efficiency analysis of ocean currents: Proposing a flow-induced vibration power-generation system with linear generator damping. Journal of Coastal Research, 39(1), 73–82. Charlotte (North Carolina), ISSN 0749-0208. The ocean current energy generation based on flow-induced vibration has mostly adopted a rotary generator, until now. In consideration of the possible shortcomings of the Vortex Induced Vibration for Aquatic Clean Energy system based on the rotary generator, this paper proposes a flow-induced coupling between the linear generator and the vibrator. For the vibration power-generation system model, this paper proposes a flow-induced vibration power-generation system model, in which the linear generator is directly coupled to the vibrator and the energy-harvesting efficiency is analyzed through numerical research methods. Results show that when the reduced velocity is 3.6 to 8.4, the energy conversion efficiency is greater and when the reduced velocity is 4.8 and the damping ratio is no more than 0.2, the maximum value of the energy conversion is 15.9%. The optimal efficiency can be achieved with the best combination of reduced velocity and damping ratio.

Wind-Electric Installation Control Based on Vibration Drive Loading under Various Energy Unit Operation Conditions

Necessity of mathematical model description of the electric power production considering not only wind loading, but also drive loading under different modes of energy-unit operation by computerized control, promoting improvement of reliability indicators of modern wind-generators components, is proved. The problem, specifications of mathematical relation between generator rotor angular speed and wind speed, blade position angle and power consumption that provides the required range of wind speed within 5-20 m/s is solved, blade position angle variation within 0 - 2% under generator rotor winding current variation not exceeding allowable error (2%) and taking account parameters affecting asynchronous generator voltage stability: induction resistance, reduced induction resistance; stator winding phase resistance, reduced stator winding phase resistance, was solved. Research Necessity of wind-electrics unit control by non-stationary operating modes under the conditions of change of measurement height of wind speed that can lead to distortion of output control results caused by the big error of measured meteorological values and consequently, negative effect on energy-unit vibrating loading, is proved. The analysis of researches made, concerning change of wind speed measurement height for wind-turbine USW56-100 has shown, that wind speed measured at 10 m height, below energy-unit by 14 m is 1m/s smaller than the actual wind speed that may icrease the error between actual and nominal angular speed of rotor wind-turbine from 3% to 17% that exceeds limits of an admissible error (2%), and generates vibrating loading of energy-unit drive and consequently, demands control, wind speed measurement height alteration by means of exponential law of a profile.

The Design and Fabrication of Waterwheels with System Floating Pontoon

The use of fossil energy is currently starting to be slightly reduced by the government, and at this time the government is also starting to look at renewable energy as alternative energy, just as energy, solar, wind, biomass, and water. One of the utilization of water energy for the use of electrical energy is with a waterwheel. In this study, a pontoon-type water wheel was designed, where the ratio of rotation of the wheel to the rotation of the generator rotor was 1: 4. The dimensions of the water wheel designed and made were with a pontoon width of 1080 mm x 2000 mm x 15 mm, and the diameter of the water wheel is 1200 mm, which can be generated by a generator of 1 kW.

Multiphase Bipolar Electret Rotary Generator for Energy Harvesting and Rotation Monitoring

Inspired by an electromagnetic generator containing multi-pole radial ring magnets, we designed a bipolar electret rotatory power generator (e-RPG) with a multi-phase core-shell structure to boost output performance and achieve high-precision self-sensing capabilities. A selectively localized rotary corona discharging method is invented to uniformly inject both positive and negative charges into a single electret’s curved surface. The experimental results show that the output power of the bipolar-charged e-RPG is increased to 384% compared with those of positive or negative charging alone, which is consistent with the results obtained from the theoretical model. By introducing the core-shell-structured multi-phase electrode design, both the rotation direction and speed can be precisely detected. The frequency sensitivity and linearity <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{R}^{2}$ </tex-math></inline-formula> (coefficient of determination) are up to 3.0 rpm/Hz and 99.9%, respectively. The proposed e-RPG has potential applications in the Internet of Things, self-powered sensing and self-sensing of rotational motions.

A PSO-Based Approach for Optimal Allocation and Sizing of Resistive-Type SFCLs to Enhance the Transient Stability of Power Systems

Transient stability improvement of power systems in the event of short-circuit faults has always been an important issue in power systems analysis and studies. Resistive-type superconducting fault current limiters (RSFCL), owing to their capability in restricting fault currents, have been often taken into account as an efficient method to improve the transient stability of a power system. Regarding technical constraints as well as economic concerns, optimal allocation and sizing of RSFCLs in a power system play a crucial role in their efficient utilization. This paper aims to continue the authors’ previous work and enhance the transient stability of power systems by proposing an optimization approach for optimal sizing and the allocation of various candidate numbers of RSFCLs, as the most employed type of SFCL and the most efficient one in transient stability improvement. To solve the optimization problem, a PSO-based algorithm is solved in MATLAB through an objective function and related constraints. The efficacy of the proposed algorithm is evaluated by numerical studies on the IEEE 39-Bus New England system in various scenarios through the assessment of critical fault clearing time (CCT) as well as the generators rotor angle deviations as two crucial criteria for the transient stability of power systems. Simulating the optimization results in DIgSILENT Power Factory indicates an evident enhancement of the power system transient stability via employing optimized RSFCLs resulted from the proposed optimization algorithm. Moreover, the level of transient stability enhancement highly depends on the number of optimized RSFCLs employed in the power system. The results of this paper present a helpful guideline for power system planners to select an appropriate stability scheme based on RSFCLs besides other related technical and economic issues.