Subject: run of river hydropower Posted: 3/3/2017 Viewed: 1326 times
I have two run of river hydropower plants placed on seperate diversions which also serve multiple agricultural demands. I do not seem to be able to divert water to these plants to create power eventhough there is enough water in the river from which the diversion takes water and there is no agricultural demand over winter.
Looking at the schematic in Priority View I notice that no figure is assigned to the plant in any of the views (supply, demand or allocation). I have set the Hydropower Priority at 50; all other supply priorities are currently set at 1.
Any suggestions where I might be going wrong?
Subject: Re: run of river hydropower Posted: 3/6/2017 Viewed: 1292 times
Don't worry about not seeing the priority number in the schematic - those don't show up for run-of-river or reservoir hydropower.
I'm not quite sure why you're having a problem with the hydropower generation. Have you tried setting the hydropower priority to 1 to see if that makes a difference?
Subject: Re: run of river hydropower Posted: 3/7/2017 Viewed: 1285 times
Yes I have tried that but I get the same result.
However I have found the problem! I had left Energy Demand and Fixed Head as what I thought were default values (i.e. 0). I had assumed that as with other variables not enetering data meant no constraint or no target whereas entering a value of 0.0 fixed the value at 0.
I can understand that one needs to provide a value for Fixed Head so that WEAP can calculate a figure for energy production. However having no defined target for Energy Demand would be useful. (In the case I am working on there are no given targets but is constrained by the maximum capacity of the plant).
Is there any way of not entering a target for Energy Demand and seeing what WEAP suggests can be produced or is the work around to put a very high target of say 1000000 and let WEAP do the rest? (I did try with a very high figure of 1000000000 and that was clearly too high as nothing was calculated).
Also perhaps this needs to be made clearer in the instructions or in the error message tab after results are run that one cannot leave these figures blank? It seems also that there is a maximum figure for Energy Demand that might need to be mentioned as well.
Subject: Re: run of river hydropower Posted: 3/7/2017 Viewed: 1281 times
Without Energy Demand, WEAP won't see a reason to reroute water from the river to the transmission links with the run-of-river hydropower (it would just produce hydropower when there happened to be water there). So it needs an energy demand.
I would think that a high figure would work. What errors are you getting?
Subject: Re: run of river hydropower Posted: 3/8/2017 Viewed: 1273 times
As I have no figures for target Energy Demand I have set an arbitrarily high demand to force WEAP to send water to the HEP. I understand that the amount sent to the HEP will be constrained by the maximum turbine flow (45CMS in this case) although if other demands are downstream of the plant then discharge can be higher. In trying to see what figure I could get away with for the arbitrary demand I increased Energy Demand over time starting with 1 million GJ increasing to 1000 Million GJ. Everything else was kept constant (supply and other demands) yet the amount diverted to HEP decreases as Energy Demand increases. If starting at 1000 GJ increasing to 1 million GJ this effect is not seen. Why should that happen? Sorry I am lost and confused!
Subject: Re: run of river hydropower Posted: 3/8/2017 Viewed: 654 times
The energy created is constrained by maximum turbine flow, but, as you said, more water can be released to demands downstream [but when in excess of max turbine flow, this flow cannot be used for energy].
You say that a increase from 1 to 1000 million GJ causes the amount diverted to decrease. That is obviously not right. I would expect to see no difference. You don't see this if starting at 1000 GJ and increasing to 1 million. Does the diverted water stay constant in that situation?