See my responses to each question below ... On Mar 3, 2020, at 10:07 AM, Yang <yang_hong_...@163.com<mailto:yang_hong_...@163.com>> wrote:
Deae Ray, Thanks for your reply, and I have dour questions as folllows. 1. If I have daily load data, like total load = [270.33 257.07 247.20 243.93 247.20 253.47 ... ](24 data), I wrote a loop to run, and use apply_changes to input these data, and change ramp rate to implement it. Is this method right? In this way, it likes I change data by hand and then I get results. From what you said, my understanding is that it takes ramp rate in account, but not very perfect. That sounds correct to me. 2. If I do as what I think in 1., the sum Pd change, and how do every bus load change? I want to use case30.m, do every bus change in proportion to the change of total load? It depends how you define the changes you apply with apply_changes(). If you are using a single value (system-wide load) and applying it with the CT_ROW column equal to 0 (apply to all rows), then, yes, it will scale the loads proportionally to make the total equal the value you specify. 3. If I want to achieve 1. by using MOST, the case is supposed to be simplified into DC model. Yes, MOST uses a linearized DC model approximation of the network. 4. If I want to reduce 10% active power of the branch 15-23 in case30.m, do I change the rate A of bus 15 or bus 23, or both? using chgtab = [1 0.002 CT_TBRCH 30 RATE_A CT_REL 0.9;]; You have to find the row index in the branch matrix of the line from bus 15 to bus 23, and use that as the row index. Hope this helps, Ray I don't know whether it is right. Warm regards. Yang. At 2020-03-03 00:31:27, "Ray Daniel Zimmerman" <r...@cornell.edu<mailto:r...@cornell.edu>> wrote: There are two main options ... If a linearized DC model of the network is adequate for your purposes, then MOST is probably the way to go. It can solve a full multi period OPF problem taking into account ramp limits. This allows restrictions in one period to affect the dispatch in previous periods, finding the dispatch trajectories that are optimal for the entire planning horizon. The other option is simply to run the single-period OPF (using runopf) sequentially for each hour in a loop and use the ramp rate to limit the feasible dispatch range in the input to runopf. That is, you would set the PMIN and PMAX for each generator in hour t to the more restrictive of (1) the physical capacity limits of the generator, (2) the maximum down/up ramp from the hour t–1 dispatch. The latter is simpler and allows you to use an AC network model, but dispatches in a given hour are not affected at all by future hours, only past hours, so the overall trajectory may not be optimal. For example, you won’t start ramping up a cheaper slow ramping unit ahead of time to be available for a peak hour, since that would require “look-ahead”. Hope this helps, Ray On Mar 1, 2020, at 12:32 PM, yang_hong_yue <yang_hong_...@163.com<mailto:yang_hong_...@163.com>> wrote: Dear Ray, I want to run opf with 24h daily load, how can I add the ramp rate constraint in code? Can I make it in add some codes or in MOST? Thanks a lot. Yang. ------------------ Original ------------------ From: Ray Daniel Zimmerman <r...@cornell.edu<mailto:r...@cornell.edu>> Date: Sat,Feb 29,2020 6:36 AM To: MATPOWER-L <matpowe...@list.cornell.edu<mailto:matpowe...@list.cornell.edu>> Subject: Re: how to modify parameter to redcuce branch power The RATE_A column of the branch matrix is used by the OPF to constrain the branch flow. Ray On Feb 28, 2020, at 7:35 AM, Yang <yang_hong_...@163.com<mailto:yang_hong_...@163.com>> wrote: Dear everyone, I want to reduce the power of branch, which parameter value should be changed in OPF? For example,if I want to reduce 50% power of branch 15-23 in case30.m, how can I make it? Thanks a lot. Best wishes. Yang
