On the Secure and Stable Operational Technology for Multi-DC Asynchronous Power-Sending Grid With High Proportion of Renewable Energy

In recent years, with a rapid growth of the generation of hydropower, wind and solar power, renewable energy has occupied more than 60% of the total installed capacity of power grids in Qinghai, Yunnan, Sichuan, Tibet and other areas. Along with the yearly increased power transmission from these provinces, the ultra-high voltage AC/DC hybrid power grids will be evolving to be the multi-DC asynchronous grid, which is a trend of future represented by the work done in Yunnan. Taking Yunnan province as an example, this article studies the operational problems related to the multi-DC asynchronous power-sending grid with high proportion of renewable energy, and describes a new secure and stable operational technology that has been applied into the grid in Yunnan. We case-study the effects of the operation after the application of such technology and evaluate its practical influences.