This paper presents a novel method for using Graph Neural Networks in combination with reinforcement learning for power reliability studies. Monte Carlo methods are the backbone of such probabilistic power system reliability analyses. Recent efforts from the authors have shown that it is possible to replace Optimal Power Flow solvers with the policies of deep reinforcement learning agents and obtain significant speedups of Monte Carlo simulations while retaining close to optimal accuracies. However, a limitation of this reinforcement learning approach is that the training of the agent is tightly connected to the specific case being analyzed, and the agent cannot be used as is in new, unseen cases. In this paper, we seek to overcome these issues. First, we represent the state and actions in the power reliability environment by features in a graph, where the adjacency matrix can vary from time step to time step. Second, we train the agent by applying a message passing graph neural network architecture to an integrated variant of an actor-critic algorithm. This implies that the agent can solve the problem independently of the power system grid structure. Third, we show that the agent can solve small extensions of a test case without having seen the new parts of the power system during training. In all of our reliability Monte Carlo simulations using this  graph neural network agent, the simulation time is competitive with that based on optimal power flow, while still retaining close to optimal accuracy.
Industrial demand response will become increasingly important in power grids with high shares of variable renewables, yet the existing knowledge on how the industrial electricity demand and flexibility will change with the decarbonization of chemical processes is limited. Here we develop a mixed-integer linear optimization model, which we use to compare the cost and flexibility of the most relevant decarbonization options for the combined chlor-alkali electrolysis (CAE) and vinyl chloride monomer (VCM) production process. We combine product and energy storage to enable the full flexibility potential of the decarbonized process. Our results show that flexible operation of the CAE process is deemed technically possible but limited by internal process dependencies due to decarbonization of the VCM production. Combining energy and product storage for demand response enables up to 4% operational cost reduction by shifting loads during peak price hours. High overcapacity of PEM electrolyzers are required to release the full flexibility potential in the hydrogen based decarbonization option, while the less flexible direct electrification option shows a potential for OPEX reduction. Full decarbonization of the combined CAE and VCM process without increasing operational cost significantly appears difficult. Our study emphasizes demand response through product and energy storages as a viable pathway for minimizing the added cost, and also enables a significant reduction of electric demand in high-price hours.