Effective Operation and Control of Hybrid Wind-Pv Water Pumping System With Minimal Power Electronics Interface

Abstract

With the growing population, the need for water and energy is compelled to increase. Employing conventional sources like fossil fuels for water pumping increases Green House Gas (GHG) emissions and the pump’s Life Cycle Cost (LCC). For a sustainable future, it is inevitable to replace these conventional energy sources with renewable energy. Furthermore, with the recent advancement in power electronics and drives, renewables like solar PV and wind energy are becoming readily available for water pumping application, reducing GHG emissions and pump’s LCC. Hence, considering the tremendous acceptance of renewable sources, especially so- lar photovoltaic (PV) and wind energy for Water Pumping System (WPS) using AC motor. This research work’s primary objective is focused on e↵ective operation and control of standalone hybrid Wind-PV WPS em- ploying Induction Motor (IM) pump with reduced part count for better utilization of renewable energy sources. The aforementioned problem statement is decomposed into solar PV fed boost converter and bidirectional Voltage Source Converter (VSC) as- sisted SEIG based Wind Energy Conversion System (WECS) to deliber- ate four notable contributions of this thesis. Firstly, a solar PV fed boost converter is investigated to examine the e↵ect of input capacitor, digital filter cut-o↵ frequency, system time constant and sampling time on imple- menting a perturbation-based Maximum Power Point Tracking (MPPT) algorithm. Based on two simple step tests, comprehensive guidelines to accomplish optimal performance of perturbation-based MPPT technique are suggested. Secondly, two algorithms are proposed for bidirectional VSC assisted SEIG feeding IM pump, one for DC-link voltage regulation (DC-link voltage regulation scheme) and another for MPPT (speed sensorless hill-climbing MPPT algorithm). The advantage of the proposed DC-link voltage reg- ulation scheme is that it senses only DC-link voltage for algorithm pro- cessing. The merit of the proposed speed sensorless hill-climbing MPPT algorithm is that it requires only dc-link voltage and two SEIG line cur- rents information and is independent of other system parameters making i the algorithm easy to implement, generic and cost-e↵ective. Additionally, these developed algorithms ensure a constant ‘V/F’ ratio of the supply at the Point of Common Coupling (PCC) for the entire operating range to prevent saturation issues concerning the SEIG and the IM pump. Deci- sively active and reactive power balance is investigated for both algorithms to demonstrate power balance at the PCC. Lastly, a stand-alone hybrid Wind-PV Water Pumping System (WPS) with minimal power electronics interface, low-complex composite controls and optimal Energy Management Strategy (EMS) for e↵ective utilization of both renewable sources is proposed. The system consists of Perturb and Observe (P&O) algorithm applied to the boost converter of the Solar PV system and voltage regulation algorithm/hill-climbing MPPT algorithm with Zero Steady-State Oscillation (ZSSO) applied to bidirectional VSC of WECS for optimal power extraction at all times. Besides optimal power extraction from the renewables, the proposed composite controller frame- work ensures a constant ‘V/F’ ratio at the PCC for the entire operating range against variations in wind velocity, solar irradiation and load. The solar PV system, WECS, the hybrid Wind-PV system and all the developed control schemes are modeled in MATLAB/Simulink and the operability of these control algorithms are experimentally verified using a low-cost TMS320F28069M controller. Extensive simulation and test results are presented to prove the viability of the proposed control schemes.