Accurate Methodology to Obtain Efficiency Mapping of Synchronous Machines

Bortoni, Edson C.; Uemori, Mauro K. I.; Araujo, Bruno T.; Bernardes, José V.; Siniscalchi, Roberto T.

doi:10.1109/pesgm41954.2020.9281622

Cited by 9 publications

(9 citation statements)

References 14 publications

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“…O VER the last decade, the load cycling intervals of large hydropower plants have changed fundamentally from rated conditions to a diverse set of operating points. As a result of a significant integration of intermittent renewable energy sources (RES) to the grid, the classical generators have responded more often to dispatch the fluctuations in both voltage and power [1]- [3]. These operating regimes bring new economic costs into consideration, as the efficiency now becomes a significant differentiator.…”

Section: Nomenclature ∆T Imentioning

confidence: 99%

“…The increasing prevalence of these kinds of operational regimes requests the need for calculation models that can accurately quantify the overall impact for hydrogenerators [7], in addition to the operational burden at the turbine-side as well [12], [13]. The calculation model weighted average efficiency (WAE) offers a viable solution to quantify the RES' impact on hydro generators [1]- [3]. The computational scheme is a sampling average approximation approach to obtain the overall operating efficiency of generators varying over different loading conditions during a finite time period.…”

Section: P(t)mentioning

confidence: 99%

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The Energy Transition's Impact on the Accumulated Average Efficiency of Large Hydrogenerators

Karekezi¹,

yvang

Nland

2022

IEEE Trans. Energy Convers.

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Section: Nomenclature ∆T Imentioning

confidence: 99%

Section: P(t)mentioning

confidence: 99%

The Energy Transition's Impact on the Accumulated Average Efficiency of Large Hydrogenerators

Karekezi¹,

yvang

Nland

2022

IEEE Trans. Energy Convers.

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“…To quantify the impact of intermittent operation, an accumulated average efficiency (AAE) model was recently proposed to improve the accuracy in the determination of the power losses [13]. It was proposed as an alternative to the mainstreamed weighted average efficiency (WAE) model [14]- [16].…”

Section: Nomenclaturementioning

confidence: 99%

Loss Modeling of Large Hydrogenerators for Cost Estimation of Reactive Power Services and Identification of Optimal Operation

Karekezi¹,

Melfald²,

Øyvang³

et al. 2022

Preprint

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<p>As a result of the worldwide energy transition, reactive power generation has started to become a more scarce resource in the power grid. Until recently, reactive power has been an auxiliary grid service that classical power generation facilities have provided without necessarily allocating any cost for this valuable service. In this paper, a new approach for predicting the additional costs of reactive power services delivered by large hydrogenerators is proposed. We derive the optimal reactive power with minimal losses as a function of the active power level within the generator's capability diagram. This pathway can then be used to calculate additional losses from operational regimes deviating from the optimal reactive power for each active power level. To back up the analysis, a dedicated population study was handpicked consisting of four real-world generators scaled in terms of power rating, i.e., 15 MVA, 47 MVA, 103 MVA, and 160 MVA. The objective was to identify how the optimal reactive power scale from smaller to larger MVA-sized generators. Moreover, a sensitivity analysis explores the link between the standard parameters, the stator losses, the rotor losses, the optimal reactive power, and the optimal efficiency. We find the ratio between the rotor and stator losses as the determining factor. Finally, the operational pathway introduces a new way to allocate the power producer's cost associated with their reactive power services and can be used to justify potential profit for this service, especially considering that the intermittent reactive power needs are projected to increase in the future. </p>

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Section: P(t)mentioning

confidence: 99%

The Energy Transition’s Impact on the Accumulated Average Efficiency of Large Hydrogenerators

Karekezi¹,

Øyvang²,

Nøland³

2021

Preprint

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<div><div><div><p>The energy transition is aimed to take advantage of the operational flexibility of hydropower to extend the in- tegration of intermittent renewable sources. Consequently, the hydrogenerators will have to operate in regimes far away from their designed best-point operation. In order to accurately assess the impact, this paper presents a useful approach to determine the overall operating efficiency of synchronous generators under intermittent operation. An accumulated average efficiency (AAE) model is proposed and compared against an alternative approach; the weighted average efficiency (WAE) model. It is found that the WAE approach produces unrealistic low efficiencies when the generator operates in synchronous condenser mode (SCM) for long periods. In general, the AAE supersedes the WAE for all the different load distributions that were investigated. This was further illustrated by a worked example and by constructing more complex load distributions. A load distribution dominated by SCM yields a difference as high as 33.18%, while an even distribution deviates 1.43 % in their respective efficiencies. Finally, a yearly on-site measurement of our studied 103MVA generator’s concentrated load distribution revealed a discrepancy of 0.67 %, which is a significant deviation considering what the operating regime would mean in terms of economic implications.</p></div></div></div>

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Accurate Methodology to Obtain Efficiency Mapping of Synchronous Machines

Cited by 9 publications

References 14 publications

The Energy Transition's Impact on the Accumulated Average Efficiency of Large Hydrogenerators

The Energy Transition's Impact on the Accumulated Average Efficiency of Large Hydrogenerators

Loss Modeling of Large Hydrogenerators for Cost Estimation of Reactive Power Services and Identification of Optimal Operation

The Energy Transition’s Impact on the Accumulated Average Efficiency of Large Hydrogenerators

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