Multilayer control for inverters in parallel operation without signal interconnection

A multilayer control is proposed for inverters with wireless parallel operation in this paper. The control is embedded in every inverter respectively and consists of three layers. The first layer is based on an improved droop method, which shares the active and reactive power in each module by adjusting the phase and amplitude of the output voltage respectively. The second layer is to compensate the droop voltage caused by the droop control and thus improve the load regulation performance of the inverter. The third layer limits the phase deviation between the inverter and the shared ac bus in order to ensure all the paralleled inverters keeping in phase. The operational principle and implementation are analyzed in details. A prototype, configured by two paralleled inverters, is set up. Experimental results verify the validity of the proposed control.