Effect of Turbine-Generator Representation in System Stability Studies

Lokay, H. E.; Bolger, Robert L.

doi:10.1109/tpas.1965.4766122

Cited by 20 publications

(3 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Changes in system frequency which affect the power-system loads have, for example, been taken into consideration by employing a system-damping coefficient 2, which will always tend to favour an optimistic assessment of performance, based on the assumption that the load falls by 1 % with 1/3% reduction in frequency, which is true only for induction-motor loads, but not for static loads, such as filament lamps and element heaters, discharge lamps, mercury-arc rectifiers, arc furnaces and electric welders; and the inclusion of the above assumptions in groups has suggested that damping has a major influence on power-system stability under transient conditions. 7 This seems difficult to accept and is inconsistent with the results of the present paper.…”

Section: Introductioncontrasting

confidence: 99%

“…Many of the above assumptions are self-compensating, and it is possible to obtain results which are reasonably accurate in practice. 7 Power-system studies, originally carried out on network analysers, now take advantage of high-speed digital computers, which offer as detailed a representation of all powersystem elements as one has the ingenuity and information to include. Comprehensive computer programs 3 ' 7 which have been developed recently do not retain the above assumptions, but it will be shown later that the treatment of damping employed therein is unsound.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transient damping torques in synchronous machines during disturbances

Akhtar

1969

Proc. Inst. Electr. Eng. UK

View full text Add to dashboard Cite

During power-system disturbances, the relative speed between the resultant flux and the rotor causes eddy currents to be induced in the rotor iron structure and an induction-motor or induction-generator torque to be developed owing to the amortisseur winding; both these effects damp out the synchronousmachine oscillations. Damping has been considered previously as directly proportional to the slip of the rotor with respect to synchronous speed for a single-machine study, and with respect to instantaneous frequency of Thevenin's equivalent e.m.f. for a multimachine study; this is erroneous and can lead to a substantially different assessment of power-system transient stability, as is shown by illustrative examples. It is indicated that the conclusions drawn from a single-machine study for damping purposes (as is sometimes done in the literature) are not really applicable to a multimachine study; and, moreover, it cannot be said with certainty that the damping will be positive or negative. The damping torque depends on the instantaneous slip between the rotor and the resultant flux, and requires knowledge of synchronous-machine torque/slip characteristics. V e v' d , X' q T" 9 ~1 D H K D eu, /o 80 8 1 List of symbols = damping power = braking power due to negative-phase-sequence current = braking power due to rapidly decaying d.c. component = negative-phase-sequence current component = d.c. component = negative-phase-sequence resistance = positive-phase-sequence resistance = infinite bus voltage = external reactance = direct-axis saturated reactance = quadrature-axis saturated reactance = Potier reactance = direct-axis transient reactance = quadrature-axis transient reactance = direct-axis subtransient reactance = quadrature-axis subtransient reactance direct-axis open-circuit transient time constant direct-axis open-circuit subtransient time constant : quadrature-axis open-circuit subtransient time constant • damping torque coefficient inertia constant slope of asynchronous characteristics expressed as p.u.-torque/p.u.-slip for synchronous machine synchronous angular velocity system nominal frequency phase angle of O at the beginning of time interval At phase angle of 0 at the end of time interval A/ phase angle of E q at the beginning of time interval Af phase angle of E q at the end of time interval A/ IntroductionIn power-system planning, various studies are normally carried out to ascertain the ability of a power system to overcome disturbances. Owing to the generally long and tedious calculations necessary, the following assumptions have been made in the past for treating synchronous machines, to achieve simplification: (a) constant flux linkages (b) transient salience neglected (c) damping torques neglected (d) voltage-regulator and -governor effects neglected (e) saturation neglected Moreover, stability has been determined by the first swing of the machine. Many of the above assumptions are self-com-

show abstract

Section: Introductioncontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transient damping torques in synchronous machines during disturbances

Akhtar

1969

Proc. Inst. Electr. Eng. UK

View full text Add to dashboard Cite

show abstract

“…The modelling of these devices and the analysis of the influence of nonlinearities in the LFC loop have been reported in the literature since the 60s, for instance [4]. One of them is the group turbine/generator.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Model Predictive Control as a LFC solution in Hydropower Plants

Donaisky

Oliveira

Santos

et al. 2015

MATEC Web of Conferences

View full text Add to dashboard Cite

Abstract. For Electric Power System safety and stable operation, planning and analysis by using simulation environments are necessary. An important point for frequency stability analysis is, on one hand, an adequate representation of Load-Frequency Control (LFC) loops and, on the other hand, the design of advanced control strategies to deal with the power system dynamic complexity. Therefore, in this paper we propose to represent the group turbine/penstock, found in hydropower plants, in a Piecewise Affine (PWA) modelling structure. Based on such modelling, we also propose the use of a Hybrid Model Predictive algorithm to be use as a control law in LFC loops. Among the advantages of this PWA representation is the use of this model in the controller algorithm, thereby improving the Load-Frequency Control performance. Simulation results, on a 200 MW hydropower plant compares the performance of predictive control strategy presented with the classical PID control strategy in an isolated condition.

show abstract

Improvement of transient stability problem for the A.R.E. 500 KV ties using optimal control

Tablawi¹,

Shabaan²

1977

IFAC Proceedings Volumes

View full text Add to dashboard Cite

Effect of Turbine-Generator Representation in System Stability Studies

Cited by 20 publications

References 2 publications

Transient damping torques in synchronous machines during disturbances

Transient damping torques in synchronous machines during disturbances

Hybrid Model Predictive Control as a LFC solution in Hydropower Plants

Improvement of transient stability problem for the A.R.E. 500 KV ties using optimal control

Contact Info

Product

Resources

About