Modelling of Environmental Constraints for Hydropower Optimization Problems – a Review

Schäffer, Linn Emelie; Adeva‐Bustos, Ana; Bakken, Tor Haakon; Helseth, Arild; Korpås, Magnus

doi:10.1109/eem49802.2020.9221918

Cited by 16 publications

(14 citation statements)

References 57 publications

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“…The impact of minimum flows and maximum ramping rates certainly limits the flexibility of the hydro system, but from a modeling point of view these constraints fit well into algorithms relying on a convex model formulation, such as SDDP. Other environmental constraints involve state-dependencies, which are not easily treated in the SDDP algorithm, as reported in Pereira-Bonvallet et al (2016) and Helseth et al (2020), and recently reviewed in Schäffer et al (2020). The main complicating factor is the nonconvexities associated with such constraints.…”

Section: Introductionmentioning

confidence: 99%

Hydropower Scheduling with State-Dependent Discharge Constraints: An SDDP Approach

Helseth

Hågenvik

et al. 2022

J. Water Resour. Plann. Manage.

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Environmental constraints in hydropower systems serve to ensure sustainable use of water resources. Through accurate treatment in hydropower scheduling, one seeks to respect such constraints in the planning phase while optimizing the utilization of hydropower. However, many environmental constraints introduce state-dependencies and even nonconvexities to the scheduling problem, making them challenging to represent in stochastic hydropower scheduling models. This paper describes how the state-dependent maximum discharge constraint, which is widely enforced in the Norwegian hydropower system, can be embedded within the stochastic dual dynamic programming (SDDP) algorithm for hydropower scheduling without compromising computational time. In this work, a combination of constraint relaxation and time-dependent auxiliary lower reservoir volume bounds is applied, and the modeling is verified through computational experiments on two different systems. The results demonstrate that the addition of an auxiliary lower bound on reservoir volume has significant potential for improved system operation, and that a bound based on the minimum accumulated inflow in the constraint period is the most efficient.

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Section: Introductionmentioning

confidence: 99%

Hydropower Scheduling with State-Dependent Discharge Constraints: An SDDP Approach

Helseth

Hågenvik

et al. 2022

J. Water Resour. Plann. Manage.

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“…Provision of upwards and downwards reserves is implicitly restricted by Eq. (32). The problem formulation is tightened further by adding Eq.…”

Section: Ramping Constraintsmentioning

confidence: 99%

Implications of environmental constraints in hydropower scheduling for a power system with limited grid and reserve capacity

Schäffer

Korpås

Bakken

2023

Preprint

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The negative impacts of power systems on biodiversity have to be mitigated, while simultaneously ensuring affordable and secure electricity supply for the future. This may lead to trade-off situations where ecological, recreational or social needs are weighted against the need for flexible power supply. This paper explores the interaction between the security of electricity supply and environmental constraints on the operation of flexible hydropower plants in the Norwegian renewable-based power system. A long-term, stochastic scheduling model of a wind- and hydropower-dominated power system is used to assess the implications of environmental constraints and reserve capacity requirements in combination. The model is used for a representative case study where three types of environmental constraints are imposed on the operation of the hydropower plants in a region of the congested Norwegian power system. In addition, requirements for spinning and non-spinning reserve capacity have to be met. The case study results demonstrate varying impacts on the operation of the hydropower plants, curtailment of demand and provision of reserve capacity depending on the type of environmental constraint being imposed.

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“…Consequently, short-term operational decisions become inconsistent with the strategy applied when making the decisions, as discussed in [28,29] in the context of approximate representation of transmission grid constraints. Similarly, some types of environmental constraints are difficult to incorporate when computing water values and may therefore lead to unnecessary operational inefficiencies [30]. Soft reservoir filling constraints are one type of environmental constraint that is often omitted or approximated in medium-term hydropower scheduling, due to the non-convex characteristics of the constraints [31].…”

Section: Hydropower Scheduling and Modelling Complexitiesmentioning

confidence: 99%

Optimal operation of hydropower systems with environmental constraints on reservoir management

Schäffer

Bakken

Helseth

et al. 2023

Preprint

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Hydropower systems' unique capability to provide flexibility and long-term energy storage makes the low-carbon technology a key contributor to cost-effective and reliable decarbonisation of power systems. To ensure sustainable operation, environmental regulations are normally imposed on the plants. Some of these regulations can be difficult to model in existing scheduling tools based on optimisation because of their non-convex and logical characteristics. This study assesses the operational impacts of two types of environmental reservoir constraints, as well as the economic impacts of considering these constraints in medium-term hydropower scheduling. The results show that optimal reservoir management may change considerably due to these types of constraints. Furthermore, improved planning results in a decent increase in expected profit to the power producer under certain price assumptions in several of the simulated cases.

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Modelling of Environmental Constraints for Hydropower Optimization Problems – a Review

Cited by 16 publications

References 57 publications

Hydropower Scheduling with State-Dependent Discharge Constraints: An SDDP Approach

Hydropower Scheduling with State-Dependent Discharge Constraints: An SDDP Approach

Implications of environmental constraints in hydropower scheduling for a power system with limited grid and reserve capacity

Optimal operation of hydropower systems with environmental constraints on reservoir management

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