Power Flow Contingency Analysis with NISQ-era Hybrid Quantum Algorithms

The US electric grid currently powers nearly 130 million households, making it essential that its operation is not interrupted by environmental factors and cybersecurity threats. We present a path towards a quantum advantage in utilities security through a hybrid quantum-classical algorithm for performing power system contingency analysis. The core of the quantum advantage lies in a Hybrid Multiple Phase Estimation Algorithm (HMPEA), which can be applied to solve a linearized model of power flow in an energy grid. We discuss how, in the era of noisy intermediate-scale quantum (NISQ) devices, HMPEA provides a more realistic approach to quantum contingency analysis than standard quantum algorithms such as HHL. We outline how this problem would be approached classically, using HHL, and using HMPEA, studying parameters such as theoretical accuracy, time complexity, qubit requirements, circuit depth, and ability to scale to large power grids in the NISQ era. Finally, we address the problem of how to best distribute quantum resources across the grid to maximize the reliability of contingency analysis.