  Series FACTS devices are one of the key enablers for very high penetration of
renewables due to their capabilities in continuously controlling power flows on
transmission lines. This paper proposes a bilevel optimization model to
optimally locate variable series reactor (VSR) and phase shifting transformer
(PST) in the transmission network considering high penetration of wind power.
The upper level problem seeks to minimize the \textcolor{black}{investment
cost} on series FACTS, the cost of wind power curtailment and possible load
shedding. The lower level problems capture the market clearing under different
operating scenarios. Due to the poor scalability of $B\theta$ formulation, the
\textsl{shift factor} structure of FACTS allocation is derived. A customized
reformulation and decomposition algorithm is designed and implemented to solve
the proposed bilevel model with binary variables in both upper and lower
levels. Detailed numerical results based on 118-bus system demonstrate the
efficient performance of the proposed planning model and the important role of
series FACTS for facilitating the integration of wind power.
