Effects of Negative-Sequence Currents on Turbine-Generator Rotors [includes discussion]

Pollard, E. I.

doi:10.1109/aieepas.1953.4498649

Cited by 13 publications

(5 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, locking the retaining ring to the rotor body is essential to ensure no mechanical stress. However, the heat from the NS current might cause a loose retaining ring which causes a significant vibration and arcing at the shrink fits [33]. In a cylindrical generator rotor, the wedges are used to hold the copper winding into the slots.…”

Section: Rotating Machinesmentioning

confidence: 99%

“…In a cylindrical generator rotor, the wedges are used to hold the copper winding into the slots. Also, the overheat from NS current in the wedges reported to cause a shear failure [33]. Additionally, [33] presents the result from an experiment which study the impact of NS current to turbine generator rotors.…”

Section: Rotating Machinesmentioning

confidence: 99%

“…Also, the overheat from NS current in the wedges reported to cause a shear failure [33]. Additionally, [33] presents the result from an experiment which study the impact of NS current to turbine generator rotors. The result shows that the rotor damage, in small generator (15-20) MW, occur due to the retaining ring overheat which happens at lower value of (I 2 2 t) than the failure of aluminium wedges (I 2 is the per unit NS current and t is time in second).…”

Section: Rotating Machinesmentioning

confidence: 99%

See 2 more Smart Citations

Balancing asymmetrical load using a static var compensator

Alsulami

Bongiorno

Srivastava

et al. 2014

IEEE PES Innovative Smart Grid Technologies, Europe

View full text Add to dashboard Cite

In practical power systems, it is normally impossible to maintain perfect balance or symmetry in phase voltages and currents. The diversity of the load, such as single phase, arc furnaces and railway, enhances the amount of unbalance or negative sequence components. Alongside asymmetrical load, further increase in negative sequence components is introduced due to the network inherent asymmetry i.e. untransposed transmission. Thus, they are usually excessive and exceeds standards at weak nodes in the network. Utilities and customers have to comply certain code agreements to limit the degree of negative sequence components in the network. This is because that negative sequence components cause deterioration to the network equipments. For instance, higher loss, torque oscillation, speed reduction and excessive rotor heat are undesirable obstacles to rotating machines. Asymmetrical load compensator can be based on passive elements, i.e. inductors and capacitors such as a Static Var Compensator (SVC), or a Voltage Source Converter (VSC) such as a Static Synchronous Compensator (STATCOM). The utilization of the negative sequence controller, an SVC or a STATCOM provides, gains a significant interest to most utilities around the globe. The compensators basically inject a different capacitive or inductive negative sequence current that has an opposite phase of the load negative sequence current. As a result, the network see symmetrical load and phase voltages and currents are balanced without exchanging active power between the network and the compensator. I would like to thank the management team Lars Stendius and Toni Blomkvist for their initial support during the summer internship and the master thesis work proposal. The financial support of this thesis was from ABB, Saudi Arabia. My acknowledgement goes to the Training Manger Awad Al-Enazy and the HR Manger Zeid Al-Rumaihi for giving me the opportunity to complete my master degree in Sweden. A special thanks is to the Talent Management Officer Mohammed Metwalli for his frequent support during the master degree. I would like to thank my family and friends in Saudi Arabia, Sweden and USA for giving me the motivation all the time. Last but not least, my greatest gratitude is to my father Meshal Alsulami (R.I.P). You will always be remembered.

show abstract

Section: Rotating Machinesmentioning

confidence: 99%

Section: Rotating Machinesmentioning

confidence: 99%

Section: Rotating Machinesmentioning

confidence: 99%

See 1 more Smart Citation

Balancing asymmetrical load using a static var compensator

Alsulami

Bongiorno

Srivastava

et al. 2014

IEEE PES Innovative Smart Grid Technologies, Europe

View full text Add to dashboard Cite

show abstract

“…Consequently, new harmonic components are induced in the magnetic field, resulting in increased rotor loss and temperature. Excessive rotor temperature rise reduces the service life of the generator, and in some severe cases [33] it may even burn the rotor insulation and the rotor core. Therefore, the investigations on the losses and the temperature variations without considering SAGE and RISC are incomplete.…”

Section: Introductionmentioning

confidence: 99%

Rotor loss and temperature variation under single and combined faults composed of static air‐gap eccentricity and rotor inter‐turn short circuit in synchronous generators

Zhang

et al. 2021

IET Electric Power Appl

View full text Add to dashboard Cite

In this study, the rotor loss as well as the temperature variations due to the static air-gap eccentricity (SAGE) and the rotor inter-turn short circuit (RISC) in synchronous generators is presented. Different from the previous studies, this study investigates the loss/ temperature changes under not only the single SAGE fault and the single RISC fault but also the combined faults (CF) that are composed of these two single faults. Detailed formula derivation on the hysteresis loss (HL) and the eddy current loss (ECL), together with the rotor temperature rise due to varied fault types and different operating conditions, are first carried out based on a theoretical analysis of the magnetic flux density (MFD) variation. Then, 3-D finite element analysis (FEA) and experimental verifications are performed on a CS-5 prototype generator that has two poles and a rated rotating speed of 3000 rpm. It shows that the occurrence of either SAGE or RISC will increase the rotor loss and temperature. Comparatively, the single RISC fault overweighs the single SAGE fault in the rotor temperature increment, while the combined fault overweighs both of these single faults. In the same fault cases, the rotor temperature will have the highest value under full-load operation.

show abstract

“…This paper investigates the magnetic field state under asymmetrical conditions. The magnetic field has been divided into the positive sequence magnetic field and negative sequence magnetic field [15][16][17][18]. The above works have only investigated the symmetrical magnetic field state.…”

Section: Introductionmentioning

confidence: 99%

Research on magnetic field state analysis of a nonsalient pole synchronous generator

Ge¹,

Lv²,

Tao³

et al. 2017

Turk J Elec Eng & Comp Sci

View full text Add to dashboard Cite

This paper is based on the definition of minor asymmetric degree and the relative position of the magnetic field. The relative position of the magnetic field is the angle between the positive and negative sequence magnetic fields.The corresponding relationship between the nonsalient pole synchronous generator steady performance and the magnetic field state is discussed when the generator operates at minor asymmetry. To analyze this corresponding relationship, the Taylor expansion formula with Lagrange remainder and symmetrical components is adopted. We study the relationship between the armature current and the relative position of the magnetic field, deducing the armature current expressions with second-order remainders. The law of the armature voltage is also obtained by phasor analysis. As an example, this paper executes two-dimensional finite element numerical calculations on a nonsalient pole synchronous generator.The result shows that the numerical calculation agrees with the deduced expression, which verifies the correctness of the expressions. In the meantime, during the process of deducing the expressions, a method of calculating the positive and negative sequence currents is proposed and their effective range is offered. When the generator works at maximum overvoltage and maximum undervoltage, the specific value of the relative position of the magnetic field is presented. This paper has important implications for generator running and protection.Key words: Minor degree of asymmetry, relative position of the magnetic field, nonsalient pole synchronous generator, positive sequence current, negative sequence current

show abstract

Effects of Negative-Sequence Currents on Turbine-Generator Rotors [includes discussion]

Cited by 13 publications

References 1 publication

Balancing asymmetrical load using a static var compensator

Balancing asymmetrical load using a static var compensator

Rotor loss and temperature variation under single and combined faults composed of static air‐gap eccentricity and rotor inter‐turn short circuit in synchronous generators

Research on magnetic field state analysis of a nonsalient pole synchronous generator

Contact Info

Product

Resources

About