Generator Shaft Research Articles

Slip Control of a Squirrel Cage Induction Generator Driven by an Electromagnetic Frequency Regulator to Achieve the Maximum Power Point Tracking

A new topology was recently developed to drive generators, aiming to avoid power electronic devices directly connected to the grid, and making possible the hybridization of the wind power with other sources. The system is composed by an induction machine with rotor in squirrel cage, and a rotating armature endowed with a three-phase winding that may be fed by a secondary source. The previous purpose was to convert a variable velocity imposed by the wind turbine to the armature in a constant velocity to be developed by the cage rotor, driving a shaft of synchronous generator. This article proposes the use of an induction generator instead of a synchronous one in order to explore the maximum available wind energy (MPPT). The simulation results show that the proposed topology is viable and supports both variations in wind speed and disturbances in power grid.

Control Strategy to Start a Shaft Generator System Employing DFIM Under Power Take Me Home Mode

Comparing to the traditional synchronous or induction electric machines, the doubly-fed induction machine (DFIM) with the partially rated converter is a good solution for a shaft generator system which normally operates within a relatively small adjustable speed range. However, the application of DFIM is limited in the real systems due to the lack of self-start capability under the power take me home (PTH) mode when the main engine fails. To overcome this problem, an approach is proposed in this paper. The basic idea is first to start the machine in the induction machine (IM) mode feeding from the ship-borne power grid (SPG) and then to switch over into the DFIM mode when the speed reaches its normal speed range. The hardware scheme, start procedure and control algorithm of the start approach are presented in the paper. Simulation and experimental studies were carried out to validate the feasibility and effectiveness of the approach.

A comparative ANSYS-based force analysis of a new horizontal-axis semi-exposed wind turbine

Renewable energy sources are growing fast. Nowadays, much effort has been made by inventors to devise new and more efficient configurations of wind turbines. This article describes the mechanical design and resultant force dynamic simulation of an innovative horizontal-axis semi-exposed wind turbine structure. The innovation in wind turbine structure includes the flat shape of its blades and their orientation towards the wind that minimizes the axial component of wind force on the shaft bearings. As a result, wind power is fully utilized to generate a useful rotary force that drives the generator rotor. This enhances the efficiency of the turbine as compared to complex shape blades in traditional horizontal-axis wind turbines. The distinctive feature of the system is also an oscillating shield that automatically protects the generator shaft from overspeeding at extreme wind speeds and, therefore, from generating power above its nominal capacity. The overspeeding may even cause physical damage to the generator. The force analysis of the new wind generator has been conducted for various wind conditions by using ANSYS Fluent. The results are compared to a traditional three-blade horizontal wind turbine to prove the ability of the new semi-exposed wind turbine to collect more driving torque on the shaft. The results of the simulation show the efficiency of the system and the advantage of using this system with the overspeed shield protection.

Feasibility Analysis for Repair of Large Diameter Hydro Turbine Shaft Based on Weldability Test and Welding Cycle Simulation

Turbine and generator rotors and shafts undergo high stresses during regular working life and, from a safety and operational aspect, are the most significant components of a power generation system. Depending on the appropriate operating conditions, like temperature and/or corrosion the, shafts can be fabricated out of low/high alloy heat resistance material or of low alloyed, highly toughened material for different application. Despite known good practice and developed operation procedures, the failures of shafts sometimes occur. The right and well-defined failure analysis is the basis for feasibility analysis of repair method in the power generating industry. The analysis of direct and indirect costs of repair after the failure analysis as well as the analysis of the repair and post-repair conditions of the repaired element is the vital for decision on the key question. Is it possible to repair this element and what is the optimal repair strategy This paper compares and analyses two approaches, by weldability analysis and weld cycle simulation, in order to determine welding feasibility analysis of cracked hydro turbine shafts.

A Rotor-Sync Signal-Based Control System of a Doubly-Fed Induction Generator in the Shaft Generation of a Ship

A doubly-fed induction machine in generator-mode is popularly used for energy generation, particularly in the case of a variable speed, such as in the wind generator, the shaft generator of a ship, because the doubly-fed induction generator is able to maintain a stable frequency when changing the rotor speed. This paper aims to propose a novel method for controlling the shaft generation system of a ship using a doubly-fed induction generator. This method uses the rotor signals of a small doubly-fed induction machine as base components to create the control signal for the doubly-fed induction generators. The proposed method will be proven by both theory and a simulation model. The advantage of the proposed method is that the control system of the generator can be simply built, but it functions effectively. The generator voltage always coincides with the grid voltage, even when the grid voltage and the rotor speed are changed, and the reactive and active power of the generator fed into the grid can be separately controlled.

Ways of reduction of pollution of an environment by ship power installations

In the report are discussed ways of reduction of pollution of an environment by ship power installations. Among them it is necessary to select optimization of regimes of operations of main traditional ship sources of the electric power, the installation of systems of utilization of refuse energy of the exhaust gases and cooling water from main and auxiliary engines, application of new types of sources of the electric power and the using of complex automation and control systems for exhaust gases and for selecting of regimes main engine, auxiliary engine, utilize boiler, auxiliary boiler, shaft generator.

A tacholess order tracking method for wind turbine planetary gearbox fault detection

Wind turbine (WT) usually works under a poor condition, its operating speed varies almost all the time, therefore, the transmission mechanism of planetary gearbox tends to occur fault to a large extent, and an effective fault detection method for WT planetary gearbox is urgently needed. However, the traditional fault detection methods which are based on constant operating speed assumption will be invalid in such a complex situation, this paper provides a novel tacholess order tracking method based on generalized demodulation (GD) for WT fault detection. Firstly, the conventional GD is modified with dual path optimization ridge estimation (DPORE) strategy, and the main innovative idea of the proposed method is that the phase reference information is obtained from the generator shaft vibration signal through GD and Hilbert transform rather than the gearbox vibration signal. Then the raw gearbox vibration signal could be resampled with uniform angle. Finally, the envelope order spectrum is obtained and the fault characteristic order (FCO) related to the WT planetary gearbox fault can be identified without auxiliary sensors. The effectiveness of the proposed method is demonstrated by real-world WT vibration signals, compound-faults on planetary gearbox can be effectively uncovered and a better performance is obtained when compared with the conventional method.

DAMPING SUB SYNCHRONOUS RESONANCE IN POWER SYSTEM USING TCSC & SVC

when the steam turbine-generator is connected with series of compensation along the transmission line, the sub synchronous resonance may happen. The Flexible Ac Transmission System (FACTS) controller of the devices wide use which has been used to reduce and suppress the phenomenon of sub-synchronous resonance the Thyristor Control Series Compensation (TCSC) and Static VAR Compensation (SVC) are the types of FACTS controller that has been used to put down the SSR and also for the purpose of provide a better and efficient solution to improve the transferred capacity system to connect the series compensation along the transmission line. Series capacitor work to increase the chance of creating sub synchronous resonance. Series capacitors also have an inclination to amplify the shaft stress during considerable network transien toccurrence, SSR phenomena happen which can cause damage of the shaft generator turbine. The first standard model of IEEE was adopted to study this phenomenon. This research deals the PID control of SVC( Static VAR Compensation) and TCSC (Thyristor Controlled Series Compensator) and excitation system controller for reducing SSR in power system. In this research, the method of Eigenvalue was used to analysis the sub-synchronous resonance phenomenon and the result was verified using DYMOLA simulation

STUDYING OF THE SOURCES OF THE DESTRUCTION OF TURBINE GENERATOR BEARING MADE OF THE BABBIT OF GRADE B83

The article is devoted to the diagnostics of friction bearing of turbine generator and determination of the reasons of its destruction during exploitation. We have studied chemistry and mechanical properties of metal, have calculated strains acting on the shaft of turbine generator in the case of asymmetrical electric load. In the article we present the results of macrostructural and microstructural analysis with usage of modern technologies. According to the data diagnosis obtained, we conclude that the source of bearing destruction is babbit fatigue damage caused by asymmetrical electric load of generator. We recommend controlling the rate of bearing wear by monitoring of babbit components presence in oil and asymmetry of electric load to prevent similar destructions.

Simulation and Study of Asynchronous Generator with a Short-Circuited Rotor with a Scalar Method of Frequency Control

The article deals with the issues of frequency scalar control of these machines with the fan nature of the moment variation on the generator shaft. It is shown that with the specified nature of the moment change, the known law of regulation for the constancy of the overload capacity (the law of Academician M.P. Kostenko) transforms into a relatively easily realizable expression establishing a relationship between the amplitude of the voltage applied to the stator winding and the product of the stator current of the asynchronous machine and the frequency rotation of its rotor. On the developed mathematical model of a frequency-controlled asynchronous machine with a short-circuited rotor, the control processes were simulated and the values of the operating parameters of the machine were obtained. Comparison of the simulation results obtained by the modified control law for the constancy of the overload capacity with the well-known and most frequently applied control law for the constancy of the magnetic flux (kus=kfs), it is shown that the proposed control option significantly exceeds the kus=kfs law in terms of reactive power consumption, while the output of active power is not very significant, but also rising. It is shown that the control on the constancy of the absolute slip β = const = sn, as expected, almost completely coincides with the control according to the law of M.P. Kostenko. Thus, the article shows that the control under the modified law of Acad. M.P. Kostenko for asynchronous generators with a fan-like nature of the load, preferably when these generators are connected to the so-called “weak” networks, i.e. to load nodes with reactive power deficit.

Variable Speed Pump Storage for the Mitigation of SSR in Power System with Wind Generation

Subsynchronous resonance (SSR) can bring significant negative effects on the grid system like stability, security, and even generator shaft damage. This work presents a new method of using a doubly‐fed induction machine (DFIM) based system of variable speed pumped storage plant (VSPS) to mitigate SSR in the power system with high penetration of wind generation. The mitigation is reached based on the principle of balanced shaft mechanical input power and electromagnetic power. The fundamental concepts and phenomena of SSR with wind farm are discussed in brief in this work. For the sake of analysis and verification of performance of the proposed system, the network model including wind farm, VSPS, HVDC, and synchronous machine is built based on Ningxia grid for the SSR study using PSCAD platform. The result shows that VSPS brings significant effect to dampen the SSR in the power system with high penetration of wind generation.

Stabilization device for hydraulic drive of an electric generator on a vehicle

The paper considers the design of a hydraulic drive of an additional electric generator installed on a car, which should provide stable electrical power to consumers with standard parameters (voltage 220 (380) V, frequency 50 Hz). To solve this problem a hydraulic regulator for a hydraulic drive connected to the motor shaft of the vehicle was proposed, it automatically stabilizes the rotational speed of the hydraulic motor shaft and the generator shaft connected to it. In this case a stable frequency current by the generator is obtained. The authors carried out selection of hydraulic machines for the proposed hydraulic drive with a rated power of generated current of 8 kW as well as a quasistatic analysis of its operation was performed.

Experimental and Educational Platform for Operation Tests and Parameterization of Power System Regulators and Stabilizers

This paper presents the development and application of an experimental and educational platform for operation testing of synchronous machines and power system regulators. This platform is composed by an asynchronous motor, which simulates the primary machine, that is coupled to a synchronous generator shaft. The platform also includes a supervisory and control system, which acts on the parameterization of the regulators and drives the primary machine and generator’s excitation field. It is possible to carry out operation tests with the generator stator running in open circuit, stand-alone or connected to the grid, and to simulate disturbances in the system to observe the power system behavior and control performance in such cases. The main contribution of this research is a real platform for experimental validation of digital models of automatic voltage regulators, power system stabilizers and governors, consequently optimizing control design and parameterization. Regarding to the teaching in power system control, the differential of this platform is the unified approach of theory understanding with the comprehension of techniques for implementation of control and instrumentation in real systems, thus contributing to the improvement of student learning, professional formation and motivation for practical activities.

An Improved Fast Detection Method on Subsynchronous Resonance in a Wind Power System With a Series Compensated Transmission Line

Subsynchronous resonance (SSR) occurs mainly in series compensated transmission line connected to the wind power system. This phenomenon (SSR) can lead to electrical instability and potential turbine generator shaft failure. Thus, the protection system is an essential part to avoid the harm of SSR. In this paper, an improved fast detection method is proposed to detect the SSR phenomenon in a very short time. It consists of two stages; first, the positive or negative half-cycle time of each cycle of voltage signal is detected based on four steps, namely, signal conversion, comparison, integrator, and sample and hold; second, the obtained time is compared with the damping and trip threshold values, and the best action is determined (addressing or trip) based on the value of half-cycle time. The effectiveness and superiority of the improved fast SSR detection method are validated at different compensation levels and compared with the traditional method and subsynchronous oscillation relay (SSO). The simulation results prove that the improved method is more efficient in all types of SSR phenomenon; induction generator effect (IGE), control interactions (CI), and torsional interaction (TI) at different compensation levels. In addition, a comparative study among these three types of SSR with the proposed method is carried out, and the obtained results show that the CI is a suitable type with the proposed method.

Method of calculating variable section shafts shear deformations

This article considered method to measure low-frequency angular oscillations of rotors of electric machines and solved the problem of assess shear deformations of rotating shafts in transient conditions. Method of calculating torsional torques is considered by the example of electric generator shaft of diesel generator unit. This method allows taking into account the angular deformations of the rotating shafts, and reducing vibration overloads, and increasing in both resource and reliability.

The design and estimation of the parameters of the vertical-axial wind-mill electric generating unit for the self-generated power supply of the objects

For the first time the experimental investigation was carried out in the wind tunnel installation to evaluate the influence of the zigzag-shaped wing flaps on the work of the H-darrieus and circular rotors. It is determined that the rotation frequency of the H-Darrieus rotor increases at the average rate of 19 per cent in the presence of these wing flaps, and the rotation frequency of the circular rotor increases at the average rate of 31 per cent in this case. It will lead to the increase of the power factor. The optimization of the geometrical parameters and the improvement of the blade construction may lead to the increase of the power factor of the H-Darrieus rotor to the point of 0.72, exceeding the maximum possible point 0.45 for the horizontal axial wind-mill electric generating unit. It is appropriate to change over to the single-stage construction of the H-Darrieus rotor with the cross members only at the bottom to connect the rotor to the shaft of the electric power generator and the thin plain bandage for fastening the blades with the wing flaps in the upper part of the rotor. It is practicable to aggregate the H-Darrieus rotors with the circular rotors for activating the rotor at the far less rotation speeds. Such a combined rotor can be used in the systems of electric power supply and heating of different objects.

The Loss of Self-Excitation Capability in Stand-Alone Synchronous Reluctance Generators

This paper analyzes the capability of synchronous reluctance generators (SynRGs) to achieve successful self-excitation when operating in stand-alone systems. To initiate the self-excitation process, the machine steel core has to retain sufficient residual flux during the generator startup. This residual flux depends on the magnetic properties of the machine core as well as the previous machine operating condition. A hysteresis model is developed to simulate the flux linkage–current characteristics of the SynRG for different operating conditions. The model then calculates the machine residual flux linkage after each operation, which indicates the machine capability for self-excitation during the next startup. The simulation results show that the rotor steel core of the synchronous reluctance machine (SynRM) can be demagnetized when the generator is subjected to a short-circuit condition or when the generator shaft is subjected to abrupt deceleration. These simulation results are also validated by experimental measurements on a 5 hp SynRM.

Experimental study of local pitch variations on electric power generated by counter rotating wind turbine with single generator without gearbox

Wind energy is one of the clean renewable energy that can be used as an alternative to reduce fossil fuel consumption. The aim of this research was to design and test the performance of counter-rotating wind turbine (CRWT) model corresponded with wind velocity and planned power output. The CRWT has two rotors with a diameter of 0.70 m comprised of NACA 4412 airfoils, which separated by axial distance of 0.3D and connected directly to each shaft of DC generator without a gearbox mechanism. In this research, local pitch (θp) of the rear rotor can be varied as followed (-10°, -5°, 0°, +5° and +10°). The data collection was done in a wind tunnel with a constant wind speed of 4 m/s, and given a load from bulb lamp started from 0 to 4.5 watt every 0.75 watts. The result shows that the local pitch +10° produced the highest rotation and electrical power generated. The highest electrical power generated at a local pitch +10° was at load 0.75 watt in amount of 1.057 watts or 23.55% higher than normal rotor (θp = 0°). At the same load, the lowest electrical power generated was at the local pitch -10° which only produced 0.598 watts.

Analysis of multimode oscillations caused by subsynchronous resonance on generator shaft

Analysis of multimode oscillations caused by subsynchronous resonance on generator shaft

ReLiShaft: realistic real-time light shaft generation taking sky illumination into account

Rendering atmospheric phenomena is known to have its basis in the fields of atmospheric optics and meteorology and is increasingly used in games and movies. Although many researchers have focused on generating and enhancing realistic light shafts, there is still room for improvement in terms of both qualification and quantification. In this paper, a new technique, called ReLiShaft, is presented to generate realistic light shafts for outdoor rendering. In the first step, a realistic light shaft with respect to the sun position and sky colour in any specific location, date and time is constructed in real-time. Then, Hemicube visibility-test radiosity is employed to reveal the effect of a generated sky colour on environments. Two different methods are considered for indoor and outdoor rendering, ray marching based on epipolar sampling for indoor environments, and filtering on regular epipolar of z-partitioning for outdoor environments. Shadow maps and shadow volumes are integrated to consider the computational costs. Through this technique, the light shaft colour is adjusted according to the sky colour in any specific location, date and time. The results show different light shaft colours in different times of day in real-time.