Hydro Composite Reservoir Table

Use of Composite Reservoirs is an optional extension to the standard Hydro Shaping Logic of Aurora. It allows treatment of systems that have both seasonal hydro storage capability and significant flexibility and discretion on timing and pricing of generation. The intent is to allow representation of the value of stored energy to be reflected in the hydro pricing and operations logic. It may be appropriate for use when modeling systems where the dispatch and pricing of hydro resources plays a significant role in marginal price determination.

The logic is activated by including a Hydro Composite Reservoir table in the study. Additionally, the Hydro Vectors table will need to include the optional Composite Reservoir column which instructs the Hydro SetHydro Set(A combination of entries in both the Hydro Monthly and Hydro Vector tables.  The set is defined by the Name column.) to use a composite reservoir for operations and pricing. Operationally, sets of individual hydro resources are tied to the composite reservoirs through hydro set composition. When a hydro set points to a valid composite reservoir, each resource using that hydro set is defined to be a member of the reservoir. Similarly to the standard logic which assumes that all units in a hydro set participate proportionally in the energy availability for a set, the assumption is made that each reservoir unit shares proportionally in the composite reservoir capability. The hourly shape parameter from the Hydro Vectors input is still used to generate an hourly availability profile, however the Proportional Load Following option is unconditionally used for any hydro set using a composite reservoir. The resulting shape profile is essentially treated as the reservoir maximum capability in an hour, however this is subject to adjustment for minimum flow constraints or to avoid unnecessary spill. Note also that only the Shape Factor is used in the hydro shaping profile logic for composite reservoirs. Instantaneous min /max, sustained peaking limits, minimum energy, and energy shift options are not currently applied.

In general terms the composite reservoir logic works as follows:

NOTE: When using composite reservoirs in a study, it is recommended that a fairly dense Dispatch Sample be used and that at least all days and all weeks be included.

NOTE: A dispatch segment will be created for each price curve used for the reservoir for each participating hydro resource. There may be a run time impact dependent on data configuration. For example, if a composite reservoir resource set consists of 1000 units and 5 price curves are used, that will create an additional 4000 dispatch segments for the dispatch and accounting logic.  Run time impacts may be reduced by eliminating unneeded granularity in resource/unit definition. Individual hydro resource dispatch segment structure and results will be output to the Resource Output tables when Segment Level Reporting is selected.

 

Data Structure

There are two types of data structures used to setup a composite reservoir:

  1. Composite Storage Reservoir

These inputs will have various definitions in the Record Type column with the data structure stored in the Value column. Most of these inputs are in the form of energy content (MWh) and include items such as maximum and minimum storage, energy inflows, minimum flow, required bypass spill levels and losses due to evaporation, leakage, etc. All of these inputs are time-series compatible.

  1. Pricing Function

These inputs will have Record Type = Price Function and define hydro energy pricing as a function of reservoir storage level using the data entered in pricing related columns (e.g., Function Content, Function Price, Shadow Resource, Price Adder and Price Factor). This structure can be thought of as a series of temporal price curves drawn through reservoir energy content levels. The pricing curves allow control of how much energy is generated from a system at different points of time and at what price. In any time period, these curves need to be monotonically increasing in price with decreasing content level. There is no limit on the number of curves used, however, each composite reservoir defined in #1 above requires at least one of these pricing structures. Note also that model run time may be affected by the number of curves used.

Each composite reservoir is assigned to a hydro set in the Hydro Vectors table via the Composite Reservoir column.

NOTE: An input table Quick View sorted first by ID and then by Record Type will make working with this table easier.

NOTE: Hydro Composite Reservoirs are not currently compatible with Risk or Commitment Optimization study types.

COLUMNS INCLUDE

Function Content

Function Price

ID

Price Adder

Price Factor

Primary Key

Record Type

Shadow Resource

Value

Input Tables

Hydro Composite Reservoir Table


For further assistance, please contact Aurora Support.

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