Conservation voltage reduction
Conservation voltage reduction
(OP)
I'm working on a cvr project on a small rural cooperative. I was hoping someone might be able to share their experiences with conservation voltage reduction. Specifically I've been wondering:
1) do you control the voltage primarily from the regulators at the substation or do you control down line devices (regulators/capacitors)
2) what has your experience shown the best bang for the buck? Ive lowered voltage 1, 2 and 3% and found that for a short period I reduced demand by greater then 10%. Is that common?
3) Are there particular loads that seem to respond better than others? How do motor loads responds?
4) is there a time limit to the cvr? I have heard some people believe that using cvr for greater then 3hrs has no benefits and the load crawels back to normal levels.
5) how do you decide to use cvr? Temperature or load forecasting?
I appreciate any help you can provide!!
1) do you control the voltage primarily from the regulators at the substation or do you control down line devices (regulators/capacitors)
2) what has your experience shown the best bang for the buck? Ive lowered voltage 1, 2 and 3% and found that for a short period I reduced demand by greater then 10%. Is that common?
3) Are there particular loads that seem to respond better than others? How do motor loads responds?
4) is there a time limit to the cvr? I have heard some people believe that using cvr for greater then 3hrs has no benefits and the load crawels back to normal levels.
5) how do you decide to use cvr? Temperature or load forecasting?
I appreciate any help you can provide!!






RE: Conservation voltage reduction
My impression is that you can expect to get roughly a 1:1 situation, that is, getting 1% demand reduction for a 1% voltage reduction. If you're getting 3% demand change for a 1% voltage change, then you're getting additional load dropping off for other reasons and not simply as a response to the voltage reduction.
There's an EPRI report on CVR that you should be able to get through NRECA.
A lot of your other questions are a little difficult to answer. When you switch on CVR, you should be comparing it to a similar day in terms of temperature, humidity and energy usage. That's the only fair comparison.
What are you trying to achieve with your CVR program? Energy reduction? Demand reduction?
RE: Conservation voltage reduction
Thanks!
RE: Conservation voltage reduction
Any load with a drive or switch mode power supply will function as a constant power load and your losses will go up as the current goes up in response to reduced voltage. Directly connected motors tend to exhibit constant power properties around nominal voltage also eliminating the possibility of gains from cvr.
Snake oil, I tell you, snake oil.
RE: Conservation voltage reduction
The problem with demand reduction schemes is that they have to be perfect. In my part of the world, there is a 12 month ratchet on peak demand. So if your demand reduction scheme misses one peak hour, you're screwed for the next year.
RE: Conservation voltage reduction
The trick is to get some smart meters (smarties) so you can actually see what your voltage profile is. Common voltage regulation practice seems to assume a primary drop in the feeder, make allowance for distribution transformers and secondary and assume you've got it. What we've seen with our smarties is that some customer voltages may already be outside of range. And those customers with low voltages may be closer to the substation than you think. Without these meters, you really don't know how far you can go with your CVR.