%0 Journal Article %A Daniel Arnold %A Michael D Sankur %A Matias Negrete-Pincetic %A Duncan S Callaway %B IEEE Transactions on Power Systems %D 2017 %G eng %N 1 %P 817 - 828 %R 10.1109/TPWRS.2017.2707405 %T Model-Free Optimal Coordination of Distributed Energy Resources for Provisioning Transmission-Level Services %V 33 %8 05/2017 %! IEEE Trans. Power Syst.