Voltage hierarchical control of flexible DC distribution network based on zero-crossing feature
The flexible DC distribution network system contains a large number of converter stations,and the voltage levels vary under different operating modes,which increases the difficulty of controlling the distribution network.Therefore,a voltage hierarchical control method based on zero crossing characteristics for the flexible DC distribution network is studied.Starting from the typical topology structure of the distribution network,analyze the distribution network with a power supply structure at both ends,and describe the operating status of the distribution network under the principle of symmetry.Set the relationship between the converter station and the active network in the distribution network,and establish a mathematical model for bidirectional transmission in the distribution network.Select the zero crossing feature theory to identify and process voltage vectors,calculate the voltage vector function value with windowed interval density,and achieve voltage hierarchical control of flexible DC distribution networks.In the experiment,a multi terminal flexible DC distribution network was used as the test object to control the voltage when the converter station was out of operation.It was found that after applying this method,effective control can be achieved both when the main station exits and when the secondary station exits.
Zero crossing featureFlexible DC distribution networkDistribution network voltageControl method
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