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BCVTB + EnergyPlus8.2 - unable to set constant value of solar radiance through the whole simulation

asked 2016-06-19 09:19:04 -0500

BBlaszczyk gravatar image

updated 2016-06-20 10:50:00 -0500

I am using EnergyPlus and BCVTB to simulate nonlinear plant model for my Matlab MPC controller. For purpose of experiment i need to set direct and diffuse solar radiance to constant value through the whole simulation. I am using EMS ExternalInterfaces:Actuators defined in this way in idf file:

ExternalInterface:Actuator,

DirSolarRad,             !- Name
Environment,             !- Actuated Component Unique Name
Weather Data,            !- Actuated Component Type
Direct Solar,            !- Actuated Component Control Type
300;                     !- Optional Initial Value

ExternalInterface:Actuator,

DiffSolarRad,            !- Name
Environment,             !- Actuated Component Unique Name
Weather Data,            !- Actuated Component Type
Diffuse Solar,           !- Actuated Component Control Type
100;                     !- Optional Initial Value

In simulation (3 days long) i set those actuators to constant values (30, 10 W/m^2). When i read output variables (Site Diffuse Solar Radiation Rate per Area, Site Direct Solar Radiation Rate per Area) i get square wave (see attached plot), not (what i want) straight horizontal lines.
For some reason during significant amount of time those values are set to 0. I suppose there is some kind of availability schedule inside, but i can't find the exact reason of this behavior.

Does anyone have any ideas what causes this behavior and how can i make those value constant in time?

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answered 2016-06-20 08:21:25 -0500

Archmage gravatar image

There is code inside EnergyPlus that zero's out the solar radiation when the sun angle is below the horizon. I don't think there is a way to change this on input.

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Isn't solar radiation already zeroed out in the EPW file? Does EnergyPlus weight the incoming radiation based on sun angles? If so, why is it weighted in the EPW file as well?

carlobianchi89 gravatar image carlobianchi89  ( 2017-10-11 16:45:52 -0500 )edit

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Asked: 2016-06-19 09:19:04 -0500

Seen: 201 times

Last updated: Jun 20 '16