Hydro

Management options

Follow load modulation

bool Defines whether the seasonal heuristic target should follow the residual demand. Used in the heuristic to dispatch inflows.

Inter-daily breakdown

float Used in the heuristic to dispatch the monthly generation target across days, proportionally to the residual demand (the load net of non-dispatchable generation, e.g. run-of-river) raised to the power of this coefficient. If equal to one, inflows are split proportionally to the residual demand; if lower than one, inflows are dispatched more evenly (flatter profile); if greater than one, more importance is given to periods of high residual demand.

Intra-daily modulation

float Value between 1 and 24, only used in the optimization when Use heuristic target is enabled. For storage power, this is the maximum authorized ratio between the daily peak and the average power generated throughout the day. The average power per day is the result of the heuristic and may not be equal to the real average power. This parameter is meant to allow simulating different hydro management strategies. Extreme cases are: 1, where the generated power must be constant throughout the day, and 24, where the whole daily energy may be used within a single hour.

Reservoir management

bool Defines whether the storage capacity should be explicitly modeled. Used in both the heuristic and the optimization: if enabled, the optimization includes a variable storage level.

Hard bounds on rules curves

bool States whether, in addition to being targeted on a best-effort basis by the preliminary heuristic stage (if any), the lower and upper reservoir rule curves should also be enforced as hard constraints in the optimization. This option is not recommended, as it could lead to infeasibility.

Use heuristic target

bool Defines whether a seasonal heuristic target should be computed for hydro generation. See the heuristic for more details.

Reservoir capacity (MWh)

float Size of the reservoir. Only used if Reservoir management is enabled, in both the heuristic and the optimization.

Inter-monthly breakdown

int Used in the heuristic to dispatch the annual inflows across months, proportionally to the residual demand (the load net of non-dispatchable generation, e.g. run-of-river) raised to the power of this coefficient. If equal to one, inflows are split proportionally to the residual demand; if lower than one, inflows are dispatched more evenly (flatter profile); if greater than one, more importance is given to periods of high residual demand.

Pumping efficiency ratio

float Between 0 and 1. Only used in the optimization. Setting the value to \(r\) means that, for the purpose of storing 1 gravitational MWh, pumps will have to use \(1/r\) electrical MWh.

Initialize reservoir level on

enum Month whose 1st day is used to initialize the reservoir level. Only used if Reservoir management is enabled, in both the heuristic and the optimization.

If the corresponding entry in the scenario builder is left to rand (the default), the initial level is drawn at random: the "initial level" is assumed to follow a "beta" variable with expectation "average level", upper bound \(U\) (max level) and lower bound \(L\) (min level) — read from the average, maximum and minimum values of the Reservoir levels time series on the initialization date — and standard deviation \(\sigma = (U-L)/3\). If a specific value is set instead in the scenario builder, that value is used directly as the initial reservoir level.

• January
• February
• March
• April
• May
• June
• July
• August
• September
• October
• November
• December

Use water values

bool States whether the energy generated from / pumped into the reservoir should be optimized based on the prices defined in the Water values table below.

Warning

When water values are used, compliance with the rule curves is not guaranteed unless the Hard bounds on rules curves option is activated, and the reservoir level at the end of the year will not necessarily be the same as at the beginning.

Use leeway

bool States whether, in the optimization, the heuristic target defined by the heuristic should be followed exactly, or within a margin defined by Leeway low bound and Leeway upper bound. Should be used together with Use heuristic target, and can be used with or without Use water values.

Power to level modulations

bool Only used in the optimization. Defines whether the standard maximum generating and pumping power should be multiplied by level-dependent modulation coefficients defined in the Credit modulations table, based on the reservoir level at the beginning of each week.

Leeway low bound

int Leeway lower bound. See Use leeway.

Leeway upper bound

int Leeway upper bound. See Use leeway.

Inflow structure

Inter-monthly correlation

float The average correlation between the energy of a month and that of the next month. Used to generate inflows if not set by the user.

Inflow pattern

matrix The average daily pattern of inflows within each month. Each day is given a relative "weight" in the month. If all days are given the same weight, daily energy time series will be obtained by dividing the monthly energy into equal days. If not, the ratio between two daily energies will be equal to that of the daily weights in the pattern array. Used to generate inflows if not set by the user.

Overall monthly hydro

matrix The expectations, standard deviations, minimum and maximum values of monthly energies (expressed in MWh), and monthly shares of run-of-river (RoR) generation within the overall monthly hydro inflow. Used to generate inflows and RoR time series if not set by the user.

Allocation

matrix Annual inter-area allocation matrix \(A(i,j)\) that may be used during a heuristic hydro pre-allocation process, regardless of whether the stochastic time series generator is used or not. This matrix describes the weights that are given to the residual demand of areas \(i\) in the definition of the monthly and weekly hydro storage generation profiles of areas \(j\).

Correlation

matrix Annual inter-area correlation matrix that will be used by the stochastic generator if it is activated. Correlations are expressed as percentages; to be valid, this matrix must be symmetric, positive semi-definite (PSD), with a main diagonal of 100s and all terms lying between -100 and +100. Used to generate inflows and RoR time series if not set by the user.

Daily power & energy credits

A "credit" is the maximum power or energy allowed for hydro generation or pumping. Standard credits set these maximum values, and credit modulations can adjust them based on the reservoir level.

Credit modulations

matrix Two level-dependent time series (101 rounded percentage values ranging from 0% to 100%) of modulation coefficients, defined for either generating or pumping.

These modulations, which can take any positive value, are only used if Power to level modulations is enabled, in which case they increase (value > 1) or decrease (value < 1) the standard credits defined below for the maximum daily power and energy, depending on the reservoir level at the beginning of each week.

Standard credits

matrix Four daily time series (365 values) defined for hourly maximum generation power, daily maximum generation energy, hourly maximum pumping power, and daily maximum pumping energy. Maximum daily energies are expressed as a number of hours at maximum power. These values are used, along with the hourly maximum power, to define a weekly maximum energy bound in the optimization, and are also used in the heuristic to define daily and monthly maximum energies.

Reservoir levels

matrix Daily time series (365 values) for the minimum, average and maximum levels set for the reservoir at the beginning of each day, expressed as a percentage of the overall reservoir volume. The lower and upper level time series form a pair of curves known as the lower and upper reservoir "rule curves".

Depending on the set of parameters chosen in the Management options tab, these rule curves may be used in different ways in the course of both the heuristic seasonal hydro pre-allocation process and the subsequent weekly optimization. See Initialize reservoir level on for details on how the initial level is derived, depending on the scenario builder configuration.

Water values

matrix Marginal values for the stored energy, which depend on the date (365 days) and the reservoir level (100 percentage values ranging from 0% to 100%). These values may have different origins. They should theoretically be obtained from a comprehensive stochastic dynamic programming study carried out over the whole dataset and dealing simultaneously with all reservoirs. Only used when Use water values is enabled.

Hydro storage

matrix Hydro inflows for each day. Only used if the generation of hydro time series is disabled; when enabled, this series is generated by Antares instead, from the Inflow structure parameters. Used in both the heuristic and the optimization. May be used immediately to generate energy if Follow load modulation is disabled, or stored in the reservoir to be generated later if Follow load modulation or Use water values is enabled.

Run of river

matrix Hourly time series of power in MW. Only used if the generation of hydro time series is disabled; when enabled, this series is generated by Antares instead, based on the run-of-river share defined in Overall monthly hydro. Used in the optimization, and in the heuristic to compute the residual demand. Run-of-river (RoR) hydroelectric generation is a type of electricity production that relies on the natural flow of a river without significant water storage, not considered in the modelling. Unlike traditional hydroelectric dams, RoR plants generate power continuously based on the river's current water level and flow rate, considered as stochastic input data, like other RES generation. This makes them highly dependent on seasonal variations and weather conditions, leading to fluctuations in electricity production.

Info

Run-of-river generation is non-dispatchable. There is no storage of energy.

Min gen

matrix Minimum generation to satisfy. Defaults to 0 if not otherwise specified. Used in the heuristic and in the optimization.