Comparison between piecewise linear and non-linear approximations applied to the disaggregation of hydraulic generation in long-term operation planning

Ramos, Tales Pulinho; Marcato, André L. M.; Brandi, Rafael Bruno da Silva; Silva, Ivo Chaves da

doi:10.1016/j.ijepes.2015.03.025

Cited by 10 publications

(5 citation statements)

References 13 publications

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“…The more energy stored in the reservoirs, the less thermal generation will be required in the future-resulting in lower future generation costs. Here, we use the methodology presented in [21] to compute the stored energy in each of Brazil's four subsystems: Southeast, South, Northeast, and North. In summary, the stored energy is an estimate of how much energy could be continuously generated by hydro plants with just the water that is currently in the reservoirs.…”

Section: Resultsmentioning

confidence: 99%

“…The changes in the reservoir volume itself depend on the net balance between the total inflow to the reservoir and the total outflow. In ( 16)-( 32), the inflow is represented by a and defined in (21) as a function of water discharges from turbines and spillages from upriver reservoirs, the term C H • ∑ j∈D ts h ∑ u∈U j q j,u,t−d j,h + s j,t−d j,h , water bypass, and pumped water, and the constant incremental inflow, I. In ( 21), D h are sets of reservoirs capable of sending water to h. For instance, D ts h is the set of all plants upriver of h whose turbine discharge and spillage reach h after d periods of time.…”

Section: Aggregated Hydrothermal Unit Commitmentmentioning

confidence: 99%

“…In ( 21), D h are sets of reservoirs capable of sending water to h. For instance, D ts h is the set of all plants upriver of h whose turbine discharge and spillage reach h after d periods of time. Similar to D ts h , D bp h is the set of upriver plants to h whose water bypass reaches h. Lastly, D pump h is the set of plants for which the pumped water arrives at h. In (21), the total inflow a is represented in the same unit as the reservoir volume, thus, all rates are converted to volumes through the constant C h . In contrast to (21), (22) gives the total outflow, o, of each plant in each period.…”

Section: Aggregated Hydrothermal Unit Commitmentmentioning

confidence: 99%

“…Similar to D ts h , D bp h is the set of upriver plants to h whose water bypass reaches h. Lastly, D pump h is the set of plants for which the pumped water arrives at h. In (21), the total inflow a is represented in the same unit as the reservoir volume, thus, all rates are converted to volumes through the constant C h . In contrast to (21), (22) gives the total outflow, o, of each plant in each period. Finally, (23) ensures that the mass balance in the reservoirs is satisfied at all times.…”

Section: Aggregated Hydrothermal Unit Commitmentmentioning

confidence: 99%

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Hydrothermal Unit-Commitment Problem of a Large-Scale System with Representation of Forbidden Zones

2021

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As we move towards electrical networks with a growing presence of renewable generation, the representation of the electrical components becomes more important. In hydro-dominated power systems, modelling the forbidden zones of hydro plants becomes increasingly challenging as the number of plants increases. Such zones are ranges of generation that either should be avoided or are altogether unreachable. However, because representing the forbidden zones introduces a substantial computational burden, hydrothermal unit-commitment problems (HTUC) for large systems are usually formulated ignoring the forbidden zones. Nonetheless, this simplification may demand adjustments to the solution of the HTUC, because the generation of the hydro stations may fall in forbidden zones. In practice, the adjustments are usually performed based on the experience of system operators and, then, can be far from an optimal correction. In this paper, we study the impact of explicitly representing the hydro-generation forbidden zones in a large-scale system with more than 7000 buses, 10,000 lines, and 700 hydro units. Our findings show that the simplified model that is current used can deviate significantly from the model with forbidden zones, both in terms of the generation of hydro plants, as well as the generation of thermal plants and the system marginal costs.

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Section: Resultsmentioning

confidence: 99%

Section: Aggregated Hydrothermal Unit Commitmentmentioning

confidence: 99%

Section: Aggregated Hydrothermal Unit Commitmentmentioning

confidence: 99%

Section: Aggregated Hydrothermal Unit Commitmentmentioning

confidence: 99%

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Hydrothermal Unit-Commitment Problem of a Large-Scale System with Representation of Forbidden Zones

2021

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“…In recent years, studies of the hydro-turbine governing system have been mainly divided into two categories. The first category focuses on operational conditions and the hydro-structure of hydropower stations [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Model validation and stochastic stability of a hydro-turbine governing system under hydraulic excitations

Chen

Tolo

et al. 2018

International Journal of Electrical Power & Energy Systems

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This paper addresses the stability of a hydro-turbine governing system under hydraulic excitations. During the operation of a hydro-turbine, water hammer with different intensities occurs frequently, resulting in the stochastic change of the cross-sectional area (A) of the penstock. In this study, we first introduce a stochastic variable u to the cross-sectional area (A) of the penstock related to the intensity of water hammer. Using the Chebyshev polynomial approximation, the stochastic hydro-turbine governing model is simplified to its equivalent deterministic model, by which the dynamic characteristics of the stochastic hydro-turbine governing system can be obtained from numerical experiments. From comparisons based on an operational hydropower station, we verify that the stochastic model is suitable for describing the dynamic behaviors of the hydro-turbine governing system in full-scale applications. We also analyze the change laws of the dynamic variables under increasing stochastic intensity. Moreover, the differential coefficient with different values is used to study the stability of the system, and stability of the hydro-turbine flow with the increasing load disturbance is also presented. Finally, all of the above numerical results supply some basis for modeling efficiently the operation of large hydropower stations.

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Long-Term Generation Scheduling: A Tutorial on the Practical Aspects of the Problem Solution

Pedrini

Finardi

2022

J Control Autom Electr Syst

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Comparison between piecewise linear and non-linear approximations applied to the disaggregation of hydraulic generation in long-term operation planning

Cited by 10 publications

References 13 publications

Hydrothermal Unit-Commitment Problem of a Large-Scale System with Representation of Forbidden Zones

Hydrothermal Unit-Commitment Problem of a Large-Scale System with Representation of Forbidden Zones

Model validation and stochastic stability of a hydro-turbine governing system under hydraulic excitations

Long-Term Generation Scheduling: A Tutorial on the Practical Aspects of the Problem Solution

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