A Novel Coordinated Control Strategy for VSC-MTDC System

Voltage source converter based multi-terminal direct current(VSC-MTDC) syetem has great advantages in renewable energy grid connection. In order to realize additional functions such as frequency support and reasonable power distribution, in this paper, a coordinated control strategy for voltage source converter based multi-terminal direct current system based on Multi-Agent System (MAS) is proposed. Firstly, a multi Agent cooperative control system for information interchange of multiple converter stations is established, The strategy regards VSC as the interface of AC and DC system, and establishes the coupling relationship between frequency in AC system and voltage in DC system. The frequency support of AC system is realized by transferring the frequency value between agents and adjusting the power distribution between VSC in real time. At the same time, Agent monitors the local VSC load rate and communicates with each other, adjusts the active power distribution in time to avoid the VSC load situation. After that, the complete control scheme of converter station based on MAS is given.Finally, based on DIgSILENT/Powerfactory power system simulation software, a 6 terminal VSC-MTDC system have been built, the effectiveness of the proposed control strategy in power grid which can control frequency effectively and allocate the active power reasonably is verified by the simulation model.