Research On Automatic Generation Control Strategy Of HVDC Islanded Sending End System

High Voltage Direct Current(HVDC)has unique advantages in long-distance and large-capacity electric power transmission,and has now become the preferred way for long-distance power transmission in China.As a special scenario of HVDC,the sending-end Islanded DC delivery system has received great attention in engineering planning and construction,due to the reason that it can avoid large-scale current transfer in AC system and reduce the risks of AC-DC parallel operation.However,the island system with small inertia lacks the support of main power grid,especially for islanded grid consisting of wind and thermal bundling,the frequency regulation capability is limited.Under the background of large-scale wind power consumptive,frequency stability has serious implications.In this paper,based on the fluctuation characteristics of wind power output,the research on the control strategy of automatic generation control(AGC)of wind-thermal bundling islanded sending end is carried out,and a strategy for real-time coordinated control of thermal units and energy storage battery systems is proposed.Based on HaZheng DC project and the main grid structure at the transmitting end,a new energy island DC delivery system model is built in PSCAD/EMTDC simulation platform including thermal power units,wind farms,energy storage batteries,and HVDC.According to the composition of the islanded grid,an AGC system based on the traditional PI controller is constructed.The operating characteristics of thermal plants are studied,and the inherent disadvantages are simulated and analyzed.Ways in which energy storage participates in AGC are also studied in this paper,strategy based on different proportion is simulated.This paper make use of the characteristics of islanded power grid to be small,and the dynamic behavior of system is easy to predict,a model predictive control(MPC)AGC controller considering SOC recovery based on was established,By building the objective function,the strategy of thermal units and energy storage frequency regulation was optimized.And the simulation analysis was performed in PSCAD/EMTDC to verify the control effect.