Research On Power Router Of Hybrid Microgrid

With the fossil energy depletion and environmental pollution,renewable energy has become increasingly prominent position in the world energy market.Micro-grid has become a hotspot because of its convenience of using renewable energy and autonomy.However,the electrical information of the micro-grid is relatively closed,and the parameters of the micro-grid are not stable,which will adversely affect the whole power system.The power router is an intelligent,flexible power converter between traditional power grid and micro-grid which is a solution of the problem.This paper starts from the principle of power router,its structure and components are studied.The topology and mathematical model are established.The energy bi-directional flow and power transformation of power router are analyzed.And the protection system is briefly introduced.Secondly,the operation and control method of grid connection mode,isolation mode and island mode are studied.And droop control is the main control strategy.The control of DC micro-grid of power router is divided into three layers by using hierarchical control of AC and DC hybrid micro-grid with main DC and auxiliary AC as models.The first layer control is the power balance control;the second layer control is the voltage control in the island mode,and the last layer control is the energy management between the energy storage unit and the power grid.At the end of this paper,the communication system of power router is briefly introduced.The function of the communication system in protection system,hierarchical control and plug-and-play function is described.In this paper,MATLAB / SIMULINK is used to verify the control method of power router and its micro-grid.Simulation results verify the effectiveness of the droop control and prove the stability of the power router in the three modes and mode switching.The results also verifies the energy bi-directional transmission function and rationality of the energy storage unit control when SOC reach the limit value.The simulation verifies the validity of the primary control when the load is removed and reconnected.The second-layer control simulation verifies the voltage synchronization control and achieves seamless switching.The last layer control simulation shows that PCC power balance can be realized by SOC control and changing the droop curve.