  Phasor Measurement Units (PMUs) are used in the measurement, control and
protection of power grids. However, deploying PMUs at every bus in a power
system is prohibitively expensive, necessitating partial PMU placement that can
ensure system observability with minimal units. One consequence of this
economic approach is increased system vulnerability to False Data Injection
Attacks (FDIAs). This paper proposes a zero-sum game-based approach to
strategically place an additional PMU (following the initial optimal PMU
deployment that ensures full observability) to bolster robustness against FDIAs
by introducing redundancy in attack-susceptible areas. To compute the Nash
equilibrium (NE) solution, we leverage a reinforcement learning algorithm that
mitigates the need for complete knowledge of the opponent's actions. The
proposed PMU deployment algorithm increases the detection rate of FDIA by 36%
compared to benchmark algorithms.
