Protection and post-fault recovery of large HVDC networks using partitioning and fast-acting DC breakers at strategic locations

Abstract

DC fault protection arrangements for a large multi-terminal HVDC (MTDC) network are proposed where fast-acting DC circuit breakers are only used at strategic locations with the large DC network to be operated interconnected but partitioned into islanded DC zones in case of any DC fault events in one of the DC zones. Each DC network zone can be protected using low cost, slow protection devices such as AC circuit breakers (ACCBs) coordinated with DC switches or slow mechanical type DC circuit breakers. This ensures the maximum ‘loss-of-infeed’ for any AC networks connected to the large HVDC system is kept within acceptable limits with reduced investment in protection cost as expensive fast-acting DC circuit breakers are kept to a minimum. A post-fault recovery method of the faulty section is proposed including the reconnection with the healthy part of the network to ensure reliable and smooth restoration of the large MTDC network. A detailed pre-fault and post-fault power flow analyses are also conducted in a MTDC network with DC voltage droop control. The proposed protection arrangements and post-fault recovery method are validated by simulation of a two-zone, six-terminal DC network with respective radial and meshed configurations.

Keywords

• distributed power generation
• circuit breakers
• power grids
• voltage control
• power transmission faults
• power distribution faults
• HVDC power transmission
• power system faults
• HVDC power convertors
• islanded DC zones
• DC fault events
• DC network zone
• slow protection devices
• AC circuit breakers
• DC switches
• mechanical type DC circuit breakers
• AC networks
• HVDC system
• protection cost
• post-fault recovery method
• MTDC network
• detailed pre-fault
• DC voltage droop control
• six-terminal DC network
• HVDC networks
• DC breakers
• strategic locations
• DC fault protection arrangements
• multiterminal HVDC network