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Re: [TRNSYS-users] simulation time error



LiaoGang,

 This is quite a common issue and the behavior you are seeing is normal. The short answer to your question is: stick to using a small time step.

 Remember that TRNSYS iterates at each timestep to find a converged solution if there are any control decisions to be made then TRNSYS can make one control decision (such as turning on or off a piece of equipment) per time step. The equipment must then stay on (or off) for the entire duration of the next timestep. If your time step is big then the system will be driven a long way from where it started before the end of the time step. Imagine if the thermostat in your home could decide to turn on heating only once per hour. If the heating had to stay on for the entire hour then chances are that the home would be uncomfortably hot by the time the thermostat was allowed to make a new decision. TRNSYS forsees this (in a way) and can't decide whether it is better to leave the heat on or off. If you shorten the time step then the on/off decision becomes quite a lot simpler and overheating and undercooling become less of a problem.

kind regards,

 David



On 04/19/2018 04:11, 廖刚 via TRNSYS-users wrote:

 Dear TRNSYS users,

 I met a very strange problem when I run my simulation model, I found that my model works well when the simulation time is relatively small, but when I increase the simulation stop time , it gives warning “The inputs to the listed units have not converged at this timestep “and then corrupted with an fatal error.

  I would be very appreciated if someone can help me solve this problem,

 Best

LiaoGang



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