A distributed autonomous control strategy is proposed for a modular photovoltaic DC grid-connected power system. Autonomous voltage balancing control of output voltages and input bus voltages without master-slave regulation of these modules are achieved by adding the information of output voltage into the input voltage reference of each module. Fully distributed and automatic control of photovoltaic DC grid-connected system with series/parallel modules and hot-swap of fault/new modules are achieved by the proposed control strategy without using communication or central controller. Simple control

easy realization and high reliability can be ensured with the proposed strategy. Experimental results have been presented to verify the feasibility and effectiveness of the proposed control strategy.