it is necessary to accomplish immediate information transmission and coordination between optimal dispatch and decentralized control. Aiming at a DC distribution system with many kinds of distributed generations
energy storage device
converter stations and loads
a hierarchical control strategy with different time scales is proposed. In a short-term time scale
the first layer control enables to realize smooth system operation in the steady-state mode by means of master-slave control; in a longer time scale
secondary voltage recovery in harsh operating condition is achieved by mode switch or adjusting tie-line power; as the third layer control
targeting maximum new energy integration and minimum network loss
energy optimal dispatch system provides operation instructions for the lower control by optimal power flow calculation. Simulation results of PSCAD/EMTDC show that when new energy power or load fluctuation occurs
the system can achieve stable control rapidly by master-slave control; when the master converter station is out-of-operation
secondary voltage recovery is achieved by adjusting tie-line power. This hierarchical control strategy realizes clear information transmission and coordinated control between optimal dispatch and decentralized control to guarantee the system to operate smoothly and economically under various conditions.
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