Interactive Solar Water Pumping Unit With Enhanced Frequency Locked Loop-Based Synchronization for Smart Residential Prosumers

An interactive solar water pumping unit (SWPU) with enhanced frequency locked loop (FLL) based synchronization to ensure uninterrupted power for smart residential prosumers is presented in this paper. Enhanced FLL ensures rejection of both DC-offset and selected harmonics unlike conventional FLL, thereby improving performance of interactive SWPU, and hence power quality of prosumers’ residential environment. A photovoltaic (PV) array, battery storage system (BSS), motor-pump unit (MPU) and power electronics interface consisting of synchronization unit (SynU), grid-connected voltage source converter (GC-VSC) and motor-connected VSC (MC-VSC) qualifies as main components of interactive SWPU. PV array and BSS supply power to both MPU and prosumers’ residential load when grid is unavailable. Once grid voltage is restored, enhanced FLL is used to synchronize SWPU with grid, thereby facilitating interoperability and interconnection between prosumers’ home and utility grid such that both of them function efficiently. Besides, current control and voltage control for operating GC-VSC are developed under presence and absence of grid. Even a sensorless control to remove motor position sensor from MPU is developed for reducing cost of SWPU. Meanwhile, test performances of interactive SWPU in different operating modes including synchronization with grid are reported to demonstrate effectiveness of enhanced FLL.