Research on the Configuration and Capacity Calculation of DC Side Dynamic Braking System

The Flexible DC Transmission technology circumvents the limitation of transmission distance caused by the charging power of AC cables. Additionally, it boasts technical advantages such as effectively isolating the interactions between onshore AC power grids and offshore wind farms, providing stable grid-connected voltage for offshore wind farms, and enabling flexible regulation of system operations. These factors make it the preferred technology for transmitting power from remote offshore wind farms. The offshore wind power flexible grid-connected system incorporates a DC-side dynamic braking system, which functions to absorb excess power injected by the wind farm and prevent system overvoltage when the AC main grid malfunctions, leading to the inability of the onshore converter station to deliver rated power. In this paper, the technical route, configuration scheme and capacity demand of DC side dynamic braking systems are studied, and the DC side dynamic braking system configuration scheme applicable to unipolar and bipolar isolated island new energy transmission flexible system is proposed, and the capacity demand of DC side dynamic braking system is analyzed, and the capacity design scheme of DC side dynamic braking system that conforms to the national calibration and meets the demand of system power balancing and fault ride-through and other requirements under the faulty AC system is proposed. The capacity design scheme of energy consuming devices is proposed in compliance with national calibration and can meet the system power balance and fault ride-through requirements in case of AC system failure and other working conditions.