Projected Gradient Descent-Based Distributed Security Control in Real Time of Medium-Voltage DC Distribution System

With the increasing demand for DC-driven sources and loads, coupled with the advantages of DC distribution, DC networking technology has become an important trend. Medium-voltage DC distribution system (MVDC-DS), which facilitates flexible interconnection of multi-region AC distribution systems and large-scale integration of distributed renewable energy sources (RESs), is faced with security challenges such as line overloads and voltage violations. Traditional control methods struggle to meet the real-time regulation requirements of the system. To solve these problems, this paper proposes a distributed security control method in real time for MVDC-DS based on projected gradient descent (PGD) method. Firstly, considering the security management constraints, an optimal operation model for MVDC-DS is established with the objective of minimizing generation cost, and the improved optimality conditions are derived by introducing projection operator. Secondly, a novel real-time distributed security control method based on PGD is proposed, which utilizes a negative feedback mechanism in the controller to achieve an iterative optimization process. On the basis, the stability and convergence of the proposed method are analyzed. Finally, simulation results verify the effectiveness and accuracy of the proposed method, which achieves both real-time security management and operating economy.