DC Ring Topology – A Comprehensive Solution to Mega City Power Grids

Mohamed Y. Haj-Maharsi


Power System Operation, power system Stability, FACTS and HVDC Transmission System, DC ring


The development of mega cities leads to increased load concentration and brings additional challenges to managing the electrical grid while keeping power available for critical loads. The evolving Shanghai power grid faces enormous challenges in the areas of generation, transmission, and distribution of the rapidly increasing amounts of electrical energy in demand. Its development should address issues of congestion, voltage stability, short-circuit power restriction, permits, and scarcity of land or right of way. In this paper, an equivalent model of the Shanghai power grid projected for 2012 is implemented using the ABB power transient software analyzer (SIMPOW) where detailed modeling of the generators including exciters and governors is performed. Solutions including Fault Current Limiters (FCL), Static Var Compensators Light (SVC-Light®) and High Voltage Direct Current (HVDC) systems were analyzed to assess their effectiveness in addressing the grid issues stated above. The optimal solution was obtained when the individual AC subsystems were decoupled so a fault in a given subsystem is not propagated to another subsystem and short-circuit currents are limited only by local generation capacity. This solution was obtained using a DC ring where power sources and loads are connected to a common DC bus through Voltage Source Converters (VSC).

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