Due　to　the　dispersion　and　randomness　of　photovoltaic　(PV)　power　generation,　the　photovoltaic　output　power　is　fluctuant.　As　the　increasing　penetration　of　photovoltaic　system,　it　plays　an　important　role　for　the　stability　of　power　system.　In　this　paper,　photovoltaic　is　combined　with　the　battery　to　form　a　photovoltaic-battery　system.　And　a　novel　control　strategy　is　proposed　to　restrain　the　photovoltaic　power　fluctuations　and　suppress　the　low　frequency　oscillations　of　power　system.　The　energy　storage　device　of　the　photovoltaic-battery　system　is　composed　of　a　battery　and　a　BUCK/BOOST　converter.　The　PV　array　and　energy　storage　device　connect　to　the　DC　side　of　the　grid-connected　inverter　in　parallel.　The　control　strategy　of　the　BUCK/　BOOST　converter　is　composed　of　voltage　loop　and　current　loop,　which　can　make　the　PV　array　work　at　the　maximum　power　point　and　decide　to　charge　or　discharge　the　battery.　And　the　control　strategy　of　the　grid-connected　inverter　is　composed　of　speed　loop,　power　loop　and　current　loop,　which　can　make　the　grid-connected　inverter　output　active　power　and　reactive　power　according　to　power　references.　Simulations　are　carried　out　with　MATLAB/SIMULINK.　And　the　practicability　of　the　proposed　control　strategy　is　verified　in　simulations.