Thesis (M.S.)--Virginia Polytechnic Institute, 1954. / Vita. Includes bibliographical references (leaves 77-78). Also available via the Internet.

Thesis (M.S.)--Virginia Polytechnic Institute, 1954. / Vita. Includes bibliographical references (leaves 65-66). Also available via the Internet.

A thesis submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2017 / The research presented in this thesis conclusively shows that the most effective method to perform synchronous turbo-generator rotor Thermal Instability Testing is by utilising the current injection method of condition assessment. Analysis of the experiences of a local utility for well over a decade has uncovered a high number of rotors failing thermal instability testing in recent years. This trend has brought the current testing methodology into question. Two different assessment modes of testing have been found to be utilised internationally without preference, namely, current injection and friction/windage. By determining the method that is best suited to detect a thermally sensitive rotor a service provider can benefit by improved rotor reliability as well as cost saving. The evaluation is accomplished by utilising a scaled down experimental setup based on the model of a local testing facility as well as a 600 MW turbo-generator rotor. A direct thermal mapping technique has been devised utilising infrared thermography to capture the thermal distribution of the rotor surface under different test conditions. The results obtained have shown that the methods differ substantially with the friction method exhibiting a uniform surface distribution and the current-injection method exhibiting areas of higher temperature concentration around the rotor pole faces. However, weaknesses do exist in present-day testing techniques in the form of inaccurate temperature measurements during testing as well as little consideration given to external factors such as the interaction between the slip-ring and brush-gear that have the potential to influence test outcomes. A presented augmented method of performing thermal sensitivity testing taking advantage of infrared thermography is found to improve testing accuracy and aid in fault detection and location. Current thermal instability testing coupled with the direct thermal mapping method has been demonstrated to be the most effective means for performing rotor thermal sensitivity testing. / MT2018

Subsynchronous Resonance (SSR) is a condition which occurs when turbogenerators are connected to series capacitively compensated transmission systems and it can cause large scale damage to the turbogenerators. The accuracy of predictions of this phenomenon are limited by the accuracy of the mathematical models used for the various system elements. The modal method of modelling a turbogenerator shaft, in which parameters are associated with each natural torsional mode of the shaft, is investigated in detail and the sensitivity of SSR predictions (both small signal and transient) to uncertainties in the mode parameters is evaluated. The modal model is then used to obtain reduced order shaft models and the accuracy of these reduced order modal models in SSR predictions is ascertained. The determination of mode parameters from generator transient response waveforms is investigated. A continuing problem in this field is the separation of damping values obtained from measurements on a synchronized generator, into their mechanical and electrical components. A method is proposed in this thesis which uses eigenvalue scanning techniques together with FFT analysis to achieve this separation. The SSR stability of, and the torsional interaction between two adjacent generators at a power station is studied. The analysis covers identical generators, nominally identical generators with small differences between their mode parameters and different generators with a coincident torsional mode. In addition, the torsional interaction between generators at different power stations which are remote from each other is investigated. This entire analysis is greatly assisted by modelling the turbogenerator shafts in modal form. Finally the damping of SSR oscillations in two non-identical adjacent turbogenerators with a single controlled shunt reactor, which uses the sum of the generator speed signals as an input to the controller, is investigated. / Thesis (Ph.D.)-University of Natal, Durban, 1987.

The ever-growing interest of the modern-day rotor dynamicist in the early detection of rotor cracks in turbomachinery has been the direct result of multiple catastrophic experiences that industry has had to face in recent times due to cracked rotors. The complete failure of the rotor due to crack propagation is easily recognized as one of the most serious modes of plant failure. Even so, this aspect has without question not received the attention it warrants. The last decade has, however, witnessed some laudable attempts that have been moderately successful in detecting cracked rotors. This work presents the design and set-up of a complete test rig that can be used for experimental research on response characteristics of cracked rotors. The results of this research will permit increased confidence in detecting the presence of rotor cracks in turbomachinery. The designed rig is capable of testing cracked shafts under the effect of lateral and coupled lateral-torsional vibrations. The conventional vibration signature analysis approach has been employed for the purpose of test rig evaluation and condition monitoring. The test rig has been shown to be essentially functional and the experimental data generated with the test rig are compared to appropriate analyses and published results. / Master of Science

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Gregory Allen Thomas. / M.S.

This investigation was conducted to determine the indicated annual savings which could be expected from the proposed installation of a 5000 Kw turbo-generator unit in the Virginia Polytechnic Institute Heating and Power Plant. These savings were determined by comparing three proposed plans of generating or purchasing electric power while supplying the college with steam. The daily log sheets and flow meter charts of the plant were used to determine the electric load curves and the steam demand curves for the year 1952. These curves were projected into the future to include the years, 1956, 1957, 1958, and 1959. These curves, together with performance curves for a 5000 Kw three stage extraction condensing turbo-generator were used in the investigation. The average outdoor temperature days were grouped in 5°F increments from 20°F through 70°F. A set of four daily load curves was plotted for each 5°F increment. Curve No. 1 shows the total electric load on the system. Curve No. 2 shows the steam demand on the plant when the proposed 5000 Kw three stage extraction condensing turbo-generator is carrying the total electric load while extracting the heating and process steam. Curve No. 3 shows the electric power that the proposed 5000 Kw two stage extraction back pressure turbo-generator would generate while meeting the heating and process steam demand. Curve No. 4 shows the total heating and process steam demand. The area under curve No.1 represents the total electric load in kilowatt-hours on the system for a day. The area under curve No. 4 represents the total heating and process steam demand in pounds for a day. The daily cost of plan No. 1 was obtained by multiplying these areas by their respective scale constants and then adding these products. The area under curve No. 3 and under curve No. 1 where curve No. 1 is below curve No. 3 represents the electric power in kilowatt-hours that could be generated by the proposed back-pressure unit. The daily saving of plan No. 2 was determined by multiplying this area by its scale constant. The daily cost of plan No. 2 was obtained by subtracting this saving from the daily cost of plan No. 1. The area under curve No. 2 and curve No. 4 where curve No. 4 is above curve No. 2 represents the steam demand in pounds for a day of the condensing unit carrying total electric load while extracting the heating and process steam. The daily cost of plan No. 3 was obtained by multiplying this area by its scale constant. The daily saving obtained by using the extraction condensing turbine over the plan of purchasing all the electric power was determined by subtracting the daily cost of plan No. 3 from that of plan No. 1. The daily saving obtained by using the extraction condensing turbine over the back-pressure turbine was determined by subtracting the daily cost of plan No. 3 from that of plan No. 2. The yearly costs and savings were determined by multiplying the daily costs and savings by the number of days in each group of average outdoor temperature days and adding these products. The expected yearly saving of plan No. 3 over plan No. 1 for 1956 would be $137,400.00, for 1957, $147,600.00; for 1958, $158,000.00 and for 1959, $171,300.00. The expected yearly saving of plan No. 3 over plan No. 2 for 1956 would be $64,300.00; for 1957, $73,200.00; for 1958, $79,900.00 and for 1959, $93,300.00. / Master of Science

This investigation was conducted to determine the indicated average heating season saving which could be expected from several different size turbines with different throttle conditions and varying stages of feedwater heating when operating in the Virginia Polytechnic Institute Central Heating and Power Plant. Such a saving in cost of power produced locally is possible because of the higher cost of power when purchased from the Appalachian Electric and Power Company. This investigation covers the heating season of 1966-1967, and assumes that the present turbo-generators will not be in use at that time. The electric load and steam demand load for the average heating season day of 1952-1953 were taken from existing records and were projected into the future to the heating season of 1966-1967. Two values were used as factors to project the steam demand into the future because of the uncertainty of the future college expansion. From this data electric load versus time curves and steam demand versus time curves were plotted for the average heating season day. This information, together with steam rates and exhaust rates for one, two, and three stage feedwater heating cycles for each proposed turbo-generator unit was used. Four curves were plotted for each throttle condition for the average heating season day in order to determine the kilowatt hours which could be generated by each proposed unit of sufficient size to supply the expected future steam demand. These curves were: Curve No. 1, the expected total electric load; Curve No. 2, the expected electric power generated by the proposed unit with one stage feedwater heating; Curve No. 3, the expected electric power generated by the proposed unit with two stage feedwater heating; Curve No. 4, the expected electric power generated by the proposed unit with three stage feedwater heating. The areas under curves two, three, and four represent the kilowatt hours which could be generated by the proposed unit supplying the expected steam demand. The value of these areas in terms of dollars saved was determined by multiplying the areas, in square inches, by a scale constant, 1000 Kw-hrs per square inch, and by $0.008 per Kw-hr minus the fuel cost per Kw-hr. The value $0.008 is the minimum rate of energy paid by the college for purchased power from the Appalachian Electric Power Company. The resulting figure represented the average daily saving for the heating season. This figure was used to calculate the total saving for the heating season. The indicated savings which might be expected for the heating season of 1966-1967 ranged from $89,000.00 for a throttle condition of 250 psig. and 500 F and a 3750 Kw unit with one stage feedwater heating to $249,480.00 for a throttle condition of 1200 psig. and 950 F and a 9375 Kw unit with one stage feedwater heating. The results for each throttle condition and turbine with varying heater stages are tabulated in part C of the investigation / Master of Science

In order to reduce emissions and achieve sustainable energy systems, renewable energy is increasingly being integrated into the power grid. However, the integration of renewable energy into the grid poses several challenges, including maintaining a stable power supply under changing and unpredictable conditions. Low Voltage Ride Through (LVRT) assesses a generator's ability to maintain stable voltage during grid voltage drops, which is crucial for renewables due to their low inertia and vulnerability to voltage disruptions caused by changes in wind or sunlight. LVRT requirements are defined by regional grid codes and regulations, which vary in their diversity. A study was conducted using Matlab Simulink to model and simulate the LVRT phenomenon on Siemens Energy's medium gas turbine generator. The entire power system generation system was simulated to observe the system's response and the generator's behavior during LVRT events. A previous gas turbine power plant project in Romania, delivered by Siemens Energy in Finspång, was simulated for analysis and compared against the grid code requirements. The findings indicated that the Siemens Energy gas turbine model SGT-750 satisfies the Romanian LVRT grid code requirements.