Re: [sumo-user] Add power-limiting to electric-vehicle model

[sumo@xxxxx]

Dear Chris,

as far as I can remember one of the problems with EV simulation is the ordering of simulation steps: The simulator first moves a vehicle according to the car following model and then uses the energy model to compute the actual power that was needed to make that step -- and if that power exceeds the rated power of the engine, you have no means to influence the already executed vehicle move. This is a side effect of CFM parametrisation: the CFM knows only about vehicle acceleration/deceleration capabilities, it makes no use of engine power and vehicle mass. If you look at the code, even if the parameter MAXIMUMPOWER is stored in the MSDevice_Battery, it is not used for anything there yet. 

We have had this problem when designing the fork of EV model for our MSDevice_ElecHybrid, and if I remember correctly, what my colleague Jakub did at the end was to extend the MSVehiclie::executeMove() to limit the maximum possible acceleration of the vehicle based on the MAXIMUMPOWER of the ElecHybrid device. This will not affect the current speed and position, but it will affect the next time step. It is not quite correct but given the separate structure of the car following subsystem and the devices, there is probably no other chance to do so (except of changing the set of CFM parameters -- the current ones are de facto standard in the microsimulation world). Contrary to some reports, our simulations show acceptably similar results to those measured in real traffic. 

I am not sure that we have made some analysis of how the trolleybus model is affected by all this (it could be that the final effect of this change is quite small; this seems to be another candidate topic to appear on our TODO list).

So, to sum it up, if you feel adventurous, try to swap your Battery for ElecHybrid. In principle, it should also work for opportunity-charged electric vehicles (but we did not test it recently; I am sending a copy of this to Jakub, he might correct me).

Hope this helps,

Jan

On Wed, 14 Oct 2020, at 4:56 PM, Chris Abraham wrote:
> Hi everyone,
> 
> It seems that the built in electric vehicle model does not limit the 
> maximum power of the vehicle. The Sumo documentation indicates that 
> there is a property called `maximumPower`. However, when I set it to a 
> value, it seems that the simulation completely ignores it, because the 
> EV still uses more than the value I specify. Additionally I would like 
> this `maximumPower` to limit the regeneration power.
> 
> Chris Abraham
> 
> 
> 
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