1186 / 2019-08-12 20:50:54

Optimal Control of MTDC for improving rotor angle stablity of AC system

Multi-terminal DC grid (MTDC),Rotor angle stability,Optimal based control,Voltage Source Converter (VSC)

Rotor angle stability of meshed AC/DC system due to the decreased effective inertia with the high penetration of renewables has become a major challenge. An easy and feasible way to enhance the rotor stability of power system provided by Multi-terminal DC (MTDC) grid is to fast modulate the power reference of standard power sharing droop control of each converter based on the rotor speed deviations of the selected generators. However, this feedback based scheme does not consider the coordination of each converter, which cannot render an optimal solution for the stability issue of the system and cannot make full use of the connected converter capability. To overcome this, this paper proposes an optimal based control of MTDC grid for improving the rotor angle stability of power system. First, MTDC grid model is well established by the linearization of power flow equations of DC grid. Then AC/DC meshed system model with the power modulation control of DC grid is further established. Furthermore, the optimal based control of MTDC grid is deduced by the online minimization of the rotor angle deviations of generators and the control energy. Finally, the nonlinear numerical simulations of one simple three generators nine buses AC/DC meshed system have demonstrated the effectiveness of the proposed optimal based scheme in three phase fault and sudden load changes in AC system.