Medium & Low-Voltage DC Power Distribution Demonstration Project, Wujiang, Suzhou

Case Details

Large-scale grid integration of wind power, photovoltaic and other new energy sources, together with rapid growth of DC loads including electric vehicles and data centers, bring prominent challenges to conventional AC power grids in terms of power conversion loss, regulation difficulty and overall energy utilization efficiency. Accordingly, developing high-efficiency, low-loss and dependable DC power supply and distribution systems has become a vital development route for the construction of new-type power systems.

As a national key research and development program project, the Wujiang medium & low-voltage DC power distribution demonstration project boasts a DC load capacity of 10 MW. Led by State Grid Jiangsu Electric Power Co., Ltd., the project covers an area of 176 square kilometers within Wujiang Economic Development Zone (Tongli Town), Suzhou City, Jiangsu Province. It is currently the most sophisticated DC power supply & distribution system worldwide with diversified application scenarios, abundant source-load categories and state-of-the-art technical equipment.

Case Highlights

DC Selective Protection

The entire power distribution system features a huge and complicated structure, where a local fault may trigger systemic impacts across the whole network. To confine system faults to the minimal scope, selective disconnection of low-voltage faults within 100 ms is mandatory, which imposes stringent requirements on the tripping characteristics of low-voltage DC circuit breakers.

LAZZEN upgrades NDM3Z series molded case circuit breakers and NDB2ZB miniature circuit breakers. A fault current limiting based selective coordination strategy is adopted to realize selective fault clearance on the low-voltage side within 100 ms. Furthermore, the system cuts off fault current within 80 ms to safeguard large-capacity power sources on the low-voltage side.

Special Application Requirements for Hybrid Supercapacitor Integrated Assemblies

LAZZEN independently develops NDW3Z-4000 DC air circuit breakers applicable for ultra-high current and ultra-high voltage working conditions. The product supports a maximum rated operating voltage of DC1500 V and integrates advanced DC sampling technology featuring high sampling precision and wide measurement range. The equipment size is further downsized to achieve intelligent high-density power distribution.