The real-time AC optimal power flow (OPF) problem is a key issue in making fast and accurate decisions to ensure the safety and economy of power systems. With the rapid development of renewable energies

the fluctuation has grown more vibrant

thus a novel approach called safe deep reinforcement learning is proposed in this paper. Herein

the real-time ACOPF problem is modeled as a constrained Markov decision process

and primal-dual optimization (PDO) based proximal policy optimization (PPO) is used to learn the optimal generator outputs in the primal domain and security constraints in the dual domain

which avoids manually selecting a tradeoff between penalties for constraint violations and rewards for the economy. Before training

behavior cloning clones the expert experience into the initial weights of neural networks. Moreover

multiprocessing training is utilized to accelerate the training speed. Case studies are conducted on the IEEE 118-bus system and the modified IEEE 118-bus system. Compared with other methods

the experimental results show that the proposed method can achieve security and near-optimal economic goals by fast calculating the real-time ACOPF problem.