  The disturbances from variable and uncertain renewable generation propagate
from power systems to natural gas networks, causing gas network operators to
adjust gas supply nominations to ensure operational security. To alleviate
expensive supply adjustments, we develop control policies to leverage instead
the flexibility of linepack -- the gas stored in pipelines -- to balance
stochastic gas extractions. These policies are based on multi-stage linear
decision rules optimized on a finite discrete horizon to guide controllable
network components, such as compressors and valves, towards feasible
operations. Our approach offers several control applications. First, it treats
the linepack as a main source of flexibility to balance disturbances from power
systems without substantial impacts on nominal gas supply. Second, these
policies can be optimized to minimize the variability (due to intermittency of
renewables) and variance (due to their uncertainty) of network state variables,
such as pressures. Finally, it enables topology optimization to decouple
network parts and prevent uncertainty propagation through the network. This is
demonstrated using illustrative numerical experiments.
