Paper Info
Title
Optimal power flow for AC-DC networks
Abstract
The presence of distributed generators with DC output power and the advancement in power electronics devices have motivated system planners and grid operators to move towards integration of DC microgrids into conventional AC grid. In this paper, we address the optimal power flow (OPF) problem in AC-DC networks. The goal of the AC-DC OPF problem is to jointly minimize the total electricity generation cost of the network and the cost of transferring active power from the AC grid to the DC microgrids. The optimization problem is subject to the power flow constraints, voltage magnitude limits, the limits of the network power lines, and the limits imposed by the power ratings of AC-DC power electronic converters. The formulated AC-DC OPF problem is shown to be nonlinear. We propose an approach to reformulate the AC-DC OPF problem as an equivalent traditional AC OPF problem. Due to the non-convexity of the AC OPF problem, we use convex relaxation techniques and transform the problem to a semidefinite program (SDP). We show that the relaxation gap is zero. That is the optimal solution of the non-convex and the transformed convex problems are equal. Simulation studies are performed on an IEEE 14-bus system connected to two 9-bus DC microgrids. We show that the sufficient condition for the zero relaxation gap is satisfied, and the proposed SDP approach enables us to find the global optimal solution efficiently.
Year
DOI
Venue
2014
10.1109/SmartGridComm.2014.7007621
Smart Grid Communications
Keywords
Field
DocType
AC-DC power convertors,costing,distributed power generation,load flow,nonlinear programming,power generation economics,9-bus DC microgrids,AC OPF problem nonconvexity,AC grid,AC-DC OPF problem,AC-DC networks,AC-DC power electronic converters,DC microgrids,DC output power,IEEE 14-bus system,OPF problem,SDP,SDP approach,active power transferring cost,convex relaxation technique,distributed generators,formulated AC-DC OPF problem,global optimal solution,grid operator,network power lines,nonconvex optimal solution,nonlinear problem,optimal power flow,optimal power flow problem,optimization problem,power electronic device,power flow constraints,power ratings,relaxation gap,semidefinite program,total electricity generation cost,voltage magnitude limits,zero relaxation gap
Power-flow study,Mathematical optimization,Power factor,Electric power transmission,AC power,Power electronics,Engineering,Optimization problem,Grid,Electricity generation
Conference
ISSN
Citations 
PageRank 
2373-6836
2
0.39
References 
Authors
3
3
Name
Order
Citations
PageRank
Shahab Bahrami1277.70
Vincent W. S. Wong239427.51
Juri Jatskevich321829.52