A Fast LP Approach for Enhanced Utilization of Variable Impedance Based FACTS Devices

Mostafa Sahraei-Ardakani, Kory Hedman

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


Transmission systems are under stress and need to be upgraded. Better utilization of the existing grid provides a fast and cheap alternative to building new transmission. One way to improve the utilization of the transmission network is power flow control via flexible ac transmission system (FACTS) devices. While FACTS devices are used today, the utilization of these devices is limited; traditional dispatch models (e.g., security constrained economic dispatch) assume a fixed, static transmission grid even though it is rather flexible. The primary barrier is the complexity that is added to the power flow problem. The mathematical representation of the DC optimal power flow, with the added modeling of FACTS devices, is a nonlinear program (NLP). This paper presents a method to convert this NLP into a mixed-integer linear program (MILP). The MILP is reformulated as a two-stage linear program, which enforces the same sign for the voltage angle differences for the lines equipped with FACTS. While this approximation does not guarantee optimality, more than 98% of the presented empirical results, based on the IEEE 118-bus and Polish systems, achieved global optimality. In the case of suboptimal solutions, the savings were still significant and the solution time was dramatically reduced.

Original languageEnglish (US)
Article number7153580
Pages (from-to)2204-2213
Number of pages10
JournalIEEE Transactions on Power Systems
Issue number3
StatePublished - May 2016


  • FACTS devices
  • linear programming
  • power generation dispatch
  • power generation economics
  • power system economics
  • power transmission economics
  • transfer capability
  • transmission topology optimization

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


Dive into the research topics of 'A Fast LP Approach for Enhanced Utilization of Variable Impedance Based FACTS Devices'. Together they form a unique fingerprint.

Cite this