  This paper proposes a new method to monitor and mitigate fault induced
delayed voltage recovery (FIDVR) phenomenon in distribution systems using
{\mu}PMU measurements in conjunction with a Reduced Distribution System Model
(RDSM). The recovery time estimated from a dynamic analysis of the FIDVR is
used to monitor its behavior and a linear optimization is formulated to control
air conditioner loads and DER reactive power injection to mitigate the FIDVR
severity. The RDSM is made up of several sub-models, each of which is analogous
to the Composite Load Model (CLM) with selected parameters. The linear
formulation in combination with the RDSM reduces the computation time, enabling
online execution. Simulated {\mu}PMU measurements from the IEEE 37 node
distribution system connected to the IEEE 9 bus system under various fault
scenarios are used to evaluate the proposed methodology. The resulting
mitigation schemes are validated using combined transmission-distribution
system simulations, thereby demonstrating that {\mu}PMU measurements along with
the RDSM enable FIDVR mitigation by optimal control of reactive power injection
from DERs with minimal load disconnection
