Research On Static Stability Of Ship-photovoltaic Grid-connected Power System

In the past 20 years,the capacity of solar photovoltaic system applied on ships has been continuous rising.Since the electric energy transformed by PV system is provided to the power load through the ship's distribution system,the output power of synchronous generator can be reduced in proportion.With the gradual improvement of the capacity of the solar energy system,the influence of the large capacity PV grid power system on the power flow and reliability of the marine power system becomes more obvious.In view of the influence of grid connected photovoltaic system on power flow and reliability of ship power system,simulation modeling and analysis of experimental results using ETAP,to explore the PV access location,current conditions under different load conditions,and short circuit for different short-circuit point analysis,reliability analysis of ship-photovoltaic power system.The results show that,the grid connected photovoltaic system in different access mode,has a little influence on power system static stability.Under the premise of ship power system running normally,with the change of the capacity of photovoltaic power,system voltage drop could be still stable,and the system branch loss is on the decline at the same time,it is benefit for efficient operation of the power grid.PV power can reduce the voltage drop of impedance load on a line,reduce the consumption of energy in its branch;and the nearer the photovoltaic power is,the less the static voltage stability index of load terminals;when access to the static load directly,it reduce the system voltage fluctuation significantly,and improve power system stability.With the increasing of inductive load ratio,the kW loss of every branch is decrease slightly.The ratio of inductive load should keep at a high level,in order to reduce the voltage drop and branch losses.When short circuit fault occurs,the photovoltaic capacity is larger,the current increasing of short-circuit is very small.Comparing to the ship power system,the small capacity pv power has little effect on short circuit,also prove that its influence on the static stability of ship power system is limited.Although small the short-circuit current is,also need us to keep photovoltaic power capacity in appropriate and reasonable restriction,to ensure that the static stability of ship power system,prevent the occurrence of system instability condition,to ensure the stability of power system.The closer the distance between grid node of photovoltaic power with fault point,the greater the fault current is,it means that location of photovoltaic power supply grid node has important influence on fault current,and protection have influence,so short circuit protection device should be placed on near grid node.The increasing ratio of inductive load can significantly improve the short circuit current of the system.Therefore,in order to steady operation of ship power grid,need to keep the inductive load ratio of ship,and the cable on ship should improve the carrying capacity of at the same time.