Renewable energy systems modelling

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This article is about planned development or proposed functionality. Comments welcome.

We should merge Energy system modelling with ASCEND into this page.

We would like to improve the capability of ASCEND in the area of modelling of renewable energy systems. In particular, we would be like to be able to model things like domestic solar hot water systems, solar thermal power stations, photovoltaic arrays, and possibly wind turbines.

ASCEND currently has the ability to solve systems of non-linear steady-state equations, as well as to integrate continuous systems of nonlinear differential-algebraic equations. There are some areas that need to be expanded, however:

  • robust reading of weather data, including wind speed, temperature, global radiation and beam radiation.
  • 'clever' smoothed interpolation of hourly solar data including estimation of the time of day when the sun sets.
  • use of short time-scale weather data, for modelling 'cloud transients'
  • models for solar collectors (with incidence angle modifier, etc)
  • models for thermal storage tanks, including stratified hot water tanks, twin-tank molten salt storage, etc.
  • models of on-off flow controllers (which requires boundary detection, see below).
  • models for stationary, single-axis and dual-axis tracking solar collectors
  • accurate calculation of sun position using unix time as the input
  • models of pressure drop in pipe flow
  • models of output from photovoltaic panels
  • models of inverters
  • models of wind turbines
  • models of pumps, turbines, compressors, heat exchangers

These models will require some new features in the ASCEND engine, including but possibly not limited to

  • boundary detection and equation reconfiguration in the IDA solver
  • support for integrating models that contain no derivatives
  • possibly improving ASCEND's DAE syntax
  • improving the ascend Data reader component
  • implementing a calculation of sun position that is more suitable for using in dynamic models
  • implementing some way of outputting simulation time (seconds) in date format (month, date, time of day)
  • improved output of simulation results (see Observers)
  • support for high-accuracy thermodynamic properties for more fluids (eg FPROPS)

Things that can hopefully be implemented as models in the ASCEND modelling language include

  • stratified tanks
  • molten salt storage tanks
  • solar collectors
  • wind turbines
  • turbines
  • pumps
  • heat exchangers
  • control valves
  • on-off controllers?