# PowerModelsAnnex QC\_OPF
**URL:** https://discourse.julialang.org/t/powermodelsannex-qc-opf/43459
**Category:** Optimization (Mathematical)
**Created:** [July 22, 2020, 12:39am UTC](https://discourse.julialang.org/t/powermodelsannex-qc-opf/43459 "2020-07-22T00:39:57Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@fnbillimoria](https://discourse.julialang.org/u/fnbillimoria)
#### Post date: [July 22, 2020, 12:39am UTC](https://discourse.julialang.org/t/powermodelsannex-qc-opf/43459/1 "2020-07-22T00:39:57Z")
I am looking through the PowerModelsAnnex.jl module and particularly the src/model/opf.jl file. I noted that there is a build of a quadratically constrained opf in there? (i.e. build\_qc\_opf) Could I please confirm what specific formulation has been used, and the paper reference if available?
Would it by any chance be Kaarthik Sundar, Harsha Nagarajan, Sidhant Misra, Mowen Lu, Carleton Coffrin and Russell Bent “Optimization-Based Bound Tightening using a Strengthened QC-Relaxation of the Optimal Power Flow Problem”, 2018 arXiv:1809.04565.
@ccoffrin @sidhant172 @harshangrjn - any thoughts would be greatly appreciated?
Many thanks
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### Author:  [@ccoffrin](https://discourse.julialang.org/u/ccoffrin)
#### Post date: [July 22, 2020, 1:13am UTC](https://discourse.julialang.org/t/powermodelsannex-qc-opf/43459/2 "2020-07-22T01:13:56Z")
Hi @fnbillimoria! That’s a good question. That model in PowerModelsAnnex is implementing the QC-TLM formulation from the referenced paper.
The way you can figure this out is to first look in the PowerModelAnnex test to see which model it is validated against, [https://github.com/lanl-ansi/PowerModelsAnnex.jl/blob/master/test/model/opf.jl#L92](https://github.com/lanl-ansi/PowerModelsAnnex.jl/blob/master/test/model/opf.jl#L92), and find the model it is compared to is, `QCLSPowerModel`.
Then look in the PowerModels documentation for a reference to this model, [Formulation Details · PowerModels](https://lanl-ansi.github.io/PowerModels.jl/stable/formulation-details/#PowerModels.QCLSPowerModel)
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### Author:  [@fnbillimoria](https://discourse.julialang.org/u/fnbillimoria)
#### Post date: [July 23, 2020, 1:21am UTC](https://discourse.julialang.org/t/powermodelsannex-qc-opf/43459/3 "2020-07-23T01:21:00Z")
Many thanks @ccoffrin ! Most appreicated.