| Under the "dual carbon" goal,the photovoltaic energy storage microgrid(PESM)which integrating photovoltaic power and energy storage has been widely used.With the increase of the operating cost of the PESM and the dependence on the power supply of the distribution network,how to consider the different power supply states in the distribution network and optimize the control load and energy storage operation is significant for improving the economy and reliability of the PESM.In addition,as an important component of the PESM,energy storage not only improves the operation economy and energy reliability,but also increases the investment cost.Therefore,when considering the multi-state operation of the PESM,how to properly configure energy storage is also worth researching.In view of the unplanned absence of power supply from the distribution network in actual operation,an operation optimal model of PESM considering important loads demand during unplanned off-grid is proposed.On the load side,considering the demand response characteristic of flexible electric load and the regulation flexibility characteristic of flexible thermal load to adjust the load demand.On the energy storage side,the state of energy level is divided,according to important loads demand,the reserve capacities during unplanned off-grid at each moment is propoesed and calculated.Taking the operation cost minimum as the goal,the simulation shows that the proposed model not only improves the economics of the grid-connected operation of the PESM,but also meets the short-term energy demand of the important loads when it is off-grid at any time at the expense of a small loss of operating cost,and improves the energy reliability,so that the operation of the PESM has both reliability and certain economy.In view of the periodic shortage of power supply in the distribution network due to insufficient power supply,an operation optimal model of the PESM considering the emergency shortage of the distribution network is proposed.On the basis of establishing the load classification model,for transferable loads,a translation optimization model is established to ease the power supply pressure during periods of low photovoltaic output,for interruptible loads,according to the estimated situation of energy storage charging and discharging power and stored energy,an interruptible load switching strategy is formulated to ensure the balance of power supply and demand in the PESM and meet the reliable power demand of important loads.The simulation example shows that the proposed model can promote the optimal utilization of the limited electric energy of the PESM in the state of emergency power shortage of the distribution network,guarantee the power demand of various loads of the PESM to a certain extent,and improve the reliability of power supply.Aiming at the optimal configuration of electric-thermal energy storage of PESM,an optimal configuration model of energy storage considering flexible load and reliable energy use is proposed.While taking the flexible load response to improve the load curve,consider the impact of the reserved energy storage capacity for reliable energy consumption on the optimal configuration of energy storage.The model aims to minimize the total annual cost,the simulation shows that considering the flexible load response can reduce the configuration capacity of energy storage and ensure the economy,considering reliable energy consumption and reserving energy storage reserve capacity will increase the investment cost,but it can ensure that the reliable energy consumption demand of important electric and thermal loads can be met at any time off-grid.In the PESM system,reasonable coordination and optimization control the operation of electrical equipment and energy storage in different states,and the optimal configuration of energy storage can effectively improve its operating economy and reliability.The work of this paper can provide reference for the operation optimization control and energy storage configuration of photovoltaic energy storage microgrid. |
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