Research On Stable Operation Technology Of DC-Microgrid

With problems plaguing the human on energy and environment, micro power grid serves as a new type of distribution network through the integration of renewable energy such as wind, solar, and some of the energy storage equipment, load to relieve the energy crisis.DC micro power grid as a form of micro power grid, has several key problems to be solved:the characteristics of the power supply, DC load characteristic, DC-DC converter topology, the DC circuit breaker, the steady state operation and fault of the control strategy, the stability of the DC micro grid global, etc.Studying the characteristics of DC micro power system stability makes an important theoretical and practical significance.Distributed power supply and load is the main component of micro grid. This paper studied the DC micro grid distributed photovoltaic power, energy storage devices and load characteristics, established the mathematical model of them, analyzed their external characteristic, and furtherly discussed their influence on stable operation of DC micro power grid.Secondly, we designed the structure of the DC micro power grid parameters, established the model of DC micro power grid, power electronic converter topologies, set up a small signal model of DC-DC converter, and switching function method was used to establish "the mathematical model of the network side converter. Using the staggered parallel topology both inner flow control, energy storage converter realized the two-way flow of energy, photovoltaic power maximum power tracking control and network side converter control.In order to realize the DC micro power grid stability control, and maintain the stability of the DC micro at different states of power grid voltage, the voltage hierarchical control strategy was used to set up a network model in PSCAD/EMTDC, and verify the validity of the control strategy. The research and development of the DC micro power grid stability controller, ensure the dynamic balance of power system. Again, on the basis of DC micro grid structure, using DC micro grid impedance normative analysis, we discussed and analysised about the stable operation range of the box, the capacity of the "source" and "load" configuration.Finally, through the actual project test platform, the micro power grid stability of the controller and the corresponding control strategy are verified.