Research On Coordinated Control Strategy For PV-battery-diesel Systems In Micro-grid

In remote areas,the power supply is not very convenient,therefore,we need to rely on micro-grid to provide residents there with electricity for living and production.Therefore,a variety of distributed power stations have been applied into the field of the micro-grid.In order to take full advantage of the distributed power,we need to coordinate control various micro-sources,while ensuring micro-grid lasting,stable and efficient.In order to improve the energy utilization and stability of the micro-grid,in this paper we will study a strategy which can coordinate the distributed power for a long time under the condition of limited capacity of hybrid energy storage system.Firstly,we build models for the distributed power of the micro-grid.By analyzing the basic working principles of photo-voltaic power generation system,diesel generator system,lead-acid battery and super capacitor,we build the grid-connected inverter model of photo-voltaic power generation system,the speed control system of diesel generator and the excitation system model,lead-acid battery model and super-capacitor model respectively,mainly for analysis of the lead-acid battery and super-capacitor charge and discharge characteristics of the simulations.Secondly,we come up with a control strategy for coordinate control hybrid energy storage system consisting of the lead-acid battery and super-capacitor to optimize the charging and discharging processes.On the basis of DC/DC converter,we design a current controller,and add measures to manage the battery charge and discharge limits and in protection of the super-capacitor terminal voltage,with the purpose to optimize charge and discharge process in the energy storage system and lengthen the period of usage.The simulation model is built and verified in MATLAB/Simulink.Finally,we research on the control strategy between the photo-voltaic power generation system,the diesel generator system and the hybrid energy storage system in the micro-grid.On the basis of the micro-grid structure established in this paper,we study the control of the lower distributed power inverter by PQ control and V/f droop control.The upper layer mainly controls the power generation sequence and power generation of eachdistributed power,including the judgment part of the working state of the hybrid energy storage system,the power calculation part of the diesel generator and the load detection part.In this paper,the micro-grid simulation model is established in MATLAB/Simulink.The control strategy is compared with the analysis of whether or not there is coordinated control strategy in the micro-grid operation.It is proved that the control method can be used to long-term stably regulate the frequency and voltage of micro-grid,reasonably distribute the power supply of the micro-sources,and effectively improve the energy utilization of the micro-grid under the condition of limited capacity of hybrid energy storage system.