# Multiperiod Integrated Ultra-Supercritical Power Plant

The Multiperiod Integrated Ultra-Supercritical Power Plant is an example model to determine the optimal schedule and operation of a pulverized coal-fired ultra-supercritical power plant integrated with thermal energy storage system (TES) for given electricity prices over a time horizon. The multiperiod model uses the Integrated Ultra-Supercritical Power Plant model for each period in the horizon. A more detailed description of the model is given in the sections below.

## Model Structure

The multiperiod power plant model is developed by creating multiple instances of Integrated Ultra-Supercritical Power Plant model, where every instance is indexed by a time period, along with two coupling variables to link each time period. These coupling variables are: the optimal power produced by the power plant and the amount of storage material available at the end of each time period. A scheme showing how the multiperiod model is constructed is shown in the figure below:

## Degrees of Freedom

The multiperiod model has a total of 4 \(n\) degrees of freedom, where \(n\) represents the number of time periods. The degrees of freedom for each time period are listed below:

Boiler feed water flow (\(boiler.inlet.flow_-mol\)),

Steam flow to charge heat exchanger (\(HXC.inlet_-1.flow_-mol\))

Condensate flow to discharge heat exchanger (\(HXD.inlet_-2.flow_-mol\)),

Cooler enthalpy at outlet (\(cooler.outlet.enth_-mol\))

## Notable Variables

Variable Name |
Description |
---|---|

\(NetPower_t\) |
Net power out from the power plant at each time period in MW |

\(SaltInventory_t\) |
Solar salt inventory at each time period in kg |

## Notable Constraints

Power plant ramping is limited by including the following equations for a given \(ramp_-rate\):

The salt inventory \(SaltInventory\) is given by the hot salt and total salt material balances, the latter involving a fixed amount of salt \(total_-salt\). The material balances are shown in the following equations:

Note that the notable constraints and variables in the multiperiod model also consider the notable variables and constraints given in Integrated Ultra-Supercritical Power Plant.