Supplementary damping control of VSC-HVDC for interarea oscillation using goal representation heuristic dynamic programming

The interarea oscillation is one of the main challenges for the secure and stable operation of a large-scale interconnected AC/DC power system. As the voltage source converter high voltage direct current (VSC-HVDC) transmission system features the fast and flexible power regulation capability, supplementary damping controller (SDC) can be designed for VSC-HVDC to suppress interarea oscillation in a large-scale AC/DC power system. In this paper, an innovative adaptive dynamic programming approach, namely the goal representation heuristic dynamic programming (GrHDP), is proposed to design SDC for VSC-HVDC. The GrHDP based SDC consists of three neural networks, which can automatically form an internal adaptive reward signal to facilitate better mapping between the system state and the control action. Therefore, the GrHDP based SDC can significantly improve the dynamic performance of the power system. Without knowing the exact mathematic model of the power system, the GrHDP based SDC still conducts the quick learning and universal control characteristics and has strong adaptability, which is superior to the conventional lead-lag SDC. Case study is undertaken based on a two-area four machine power system with one VSC-HVDC transmission line. The conventional lead-lag SDC has also been studied for comparison. Simulation results show that the proposed GrHDP based SDC has better performance in damping interarea oscillation than that of the conventional lead-lag SDC in a wide range of system operating conditions.