Research On Multi-level Distributed Photovoltaic Consumption Strategies Based On Energy Routers

With the depletion of traditional fossil energy and the increasingly worsening environmental problems,new energy generation technologies represented by distributed photovoltaics have developed rapidly.However,under the constraints of voltage level and harmonic content,distributed photovoltaics can not be directly and massively connected to traditional distribution network.In order to improve the capacity of distribution network for distributed photovoltaics,this thesis studies the topology of an AC-DC hybrid distribution network based on energy routers,and studies the four-level consumption strategy of distributed photovoltaics under this structure.Firstly,the topology of an energy router is studied in this thesis,which includes a gateway converter,a mutual converter,an AC load port converter and a DC load port converter.The thesis analyzes the working principle,control method and power transmission characteristics of each converter.Secondly,this thesis studies the four-level consumption strategy of distributed photovoltaic in a new AC/DC hybrid distribution network based on energy routers.The first level of consumption is the busbar internal consumption.Photovoltaic connected to the AC/DC hybrid distribution network must first complete the first level consumption,and try to meet the power demand of the bus.The second level of consumption is cross-busbar consumption.When the distributed photovoltaic output is greater than the total load of the bus,the remaining power in the bus is transmitted to the bus with power shortage.The third level of consumption is the cross-substation area consumption.When the PV output in the station area is greater than the total load,the excess power inside the station area is transmitted to the power station with power shortage through the DC mutual aid bus.The fourth level of consumption is returning the energy to the power grid.When each station has power surplus,the remaining power will be returned to the power grid separately.For the third-level consumption,this thesis proposes a variable-intercept adaptive droop control strategy.The strategy can adaptively adjust the intercept of the droop curve according to the real-time power of the PV output and the load of each station.So the surplus power can be transmitted from the station with power remaining to the station with power shortage through the DC mutual aid bus.At the same time,the stability of the mutual aid bus voltage is maintained.In this way,energy support can be achieved between the stations,and multi-level consumption of distributed photovoltaics can be achieved.Since the remaining power generation is not directly injected into the distribution network,the impact on the distribution network can be reduced.Finally,this thesis verifies the PV four-level consumption in the MATLAB/Simulink simulation environment.In order to further verify the validity and correctness of the variable-intercept adaptive droop control strategy,this thesis also builds an AC-DC hybrid distribution network simulation model including three energy routers,and set the PV output sufficient or zero in each station.Simulations were carried out under extreme conditions such as sudden load changes in some stations.The simulation results show that the AC/DC hybrid distribution network based on energy router can realize the four-level consumption of distributed photovoltaic.