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:

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

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

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

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

Notable Variables

Variable Name



Net power out from the power plant at each time period in MW


Solar salt inventory at each time period in kg

Notable Constraints

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

\[NetPower_{t-1} - ramp_-rate \leq NetPower_t\]
\[NetPower_{t-1} + ramp_-rate \geq NetPower_t\]
  1. 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:

\[HotSaltInventory_t = HotSaltInventory_{t-1} + F^{charge}_{salt, outlet} - F^{discharge}_{salt, inlet}\]
\[total_-salt = HotSaltInventory_t + ColdSaltInventory_t\]

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.