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Proposal for a High Quality dc Network with Distributed Generation. A. Agustoni, M. Brenna, E. Tironi Politecnico di Milano – Italy G. Ubezio SIEL S.p.A. – Italy. Introduction. Integration in a local dc distribution network. Need of high-quality power supply UPS with dc section
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Proposal for a High Quality dc Network with Distributed Generation A. Agustoni, M. Brenna, E. Tironi Politecnico di Milano – Italy G. Ubezio SIEL S.p.A. – Italy
Introduction Integration in a local dc distribution network Need of high-quality power supply UPS with dc section Distributed Generation Generation in dc Electronic devices dc section
dc bus ac public network ac users public network dc users dc users ac generators ac generators dc users ac users dc generators storage ac users dc generators dc users storage storage Comparison between ac and dc distribution systems
dc distribution advantages • Island operation • Reduction of power converters number and their complexity • Increase in power quality for • end users • public network • Better integration of DG
dc system choice criteria Keep the same ac distribution systems apparatuses Sinusoidal absorbtion Bidirectional power flow Forced-commutated ac/dc interface converter Same MV/LV substation transformer dc voltage = ±400 V
Proposed network schemes Use existing distribution lines 1 2 3 N load load load DG storage PE
Proposed network schemes Connection of the neutral to the grounding system of MV/LV substation 1 2 3 N load load load DG storage PE
Control system – characteristics • dc bus is the only connection common to all converters control system is based on dc voltage • Presence of different supply sources possibility to integrate and optimize system management with field bus systems • Control system must be robust
Control system – functions • Keep dc voltage within acceptable range • Renewable generators must supply all the available power, if loads, network or storage systems can absorb it • Storage systems have to be recharged as soon as possible and need to be discharged if necessary • ac/dc interface converter has to absorb or deliver power from or to the network
Control system – strategy By varying the reference values is possible to adjust system performance
Simulation results ac input currents dc bus voltage renewable power delivered storage system current
Conclusion • A new dc distribution system has been proposed • The system permits an increase in power quality both for end users and network • The system allows an easier integration of DG • It is possible to optimize the system management by means of field bus systems
Simulation results power absorbed from the network ac voltages
Simulation results ac input current and phase voltage ac input currents storage system current dc bus voltage
Simulation results renewable power delivered power absorbed from the network ac voltages
Storage system Photovoltaic arrays DC-DC Converter DC Bus Inverter Rectifier Loads Auxiliary generator A dc distribution system realization