Pumping of water requires excessive energy for its operation by consuming a massive amount of diesel, gasoline, electric power etc. The more promising alternative energies to perform the same operation without any energy cost are solar photovoltaic (PV) and wind. These fastest growing renewable energies are more reliable and well suitable for remote villages where there is no possibility of extending transmission lines. Furthermore, these systems are optimal for conditions like only small amount of water needed to be pumped for a particular time. Unlike conventional energy sources of electric power, the renewable energy sources are not dispatchable its power output cannot be controlled. In that case, it involves power conversion stages so that it would necessitate to design an advanced control strategy technique. Those control strategies greatly avoid and protects the system from detrimental operating conditions by monitoring input voltage, water flow, torque, power, pressure, speed and motor vibration etc. Henceforth the use of efficient control strategy not only increase the performance of system it also helps to increase the number of operational hours of solar PV and wind energy systems. In this manuscript, the research work of various control strategies carried out in solar PV and wind energy-based water pumping systems are presented. Additionally, this paper intends to discuss the energy management strategies applied for renewable energy fed water pumping system when the system assisted with third energy system (battery bank, fuel cell, etc). These benefited systems ensure good design, guarantees the control speed required for the motor, regulates the flow of water, assuring accurate operation for all conversion and finally, it maintains precise balance in between the renewable energy generated and power required by the load (pump).

Control and energy management strategies applied for solar photovoltaic and wind energy fed water pumping system: A review

Analysis of logic gates for the switching sequence operation of reduced switch multilevel inverter (MLI) is introduced in this paper. Two variants of MLI with reduced switches are considered for the analysis of the logic gates to obtain proper output voltage level. One MLI is with the symmetrical voltage, and the other is with the asymmetrical voltage. The analysis of the proposed logical operation is presented through the single-phase seven-level output voltage for both symmetrical and asymmetrical inverters. Input pulse pattern for the operation of the logic gates are chosen from the multi carrier pulse width modulation (PWM) techniques as phase disposition (PD), phase opposition disposition (POD), and alternate POD (APOD). The analysis for the generation of the required pulse pattern to operate the switches in MLI is presented as logical equations. The simulation work is performed and evaluated with the MATLAB/Simulink. The real-time simulation is performed for the required pulse pattern and generated with the support of dSPACE 1104. The THD comparative analysis is analyzed with a modulation index and various PWM methods.

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Analysis of Logic Gates for Generation of Switching Sequence in Symmetric and Asymmetric Reduced Switch Multilevel Inverter

This paper proposes a new single-phase 11-level transformerless symmetric/asymmetric inverter with a reduced number of switches. The proposed structure is capable of generating high voltage levels with a lower number of power components (including power switches and gate drivers) for both symmetrical and asymmetrical structures. The symmetric results of the proposed topology are compared with the other symmetric 11-level structures in terms of total harmonic distortion, overall efficiency, total number of switches, number of gate drives and required dc sources. The results show that the system's overall efficiency is high; hence, the system's life span will be high. To regulate the injected current, the model predictive control is applied to control the switches in order to be able to follow the reference current. The performance of the proposed structure is verified by the simulation (PSCAD) results.

A New Transformerless Single-Phase Eleven-Level Inverter with Reduction of Switches Based on Model Predictive Control Method

Solar photovoltaic powered water pumping systems are becoming very successful in regions where there is no opportunity for connecting the grid. The photovoltaic technology converts solar energy into electrical energy for operating DC or AC motor-based water pump. In the case of a solar AC motor water pump, it engages two energy conversion stages (DC-DC and DC-AC) in the power conditioning unit. This usually resulted in increased size, cost, complexity and decreases efficiency of the entire system. In addition, the existing two-level inverter (DC-AC) stage generates higher harmonics in output voltage that deteriorates AC motor performance. As a consequence, a single energy conversion stage with more than two-level output voltage could be possible by utilizing multilevel inverters which replaces two-level inversion stage easily to get higher levels of output voltages as well for extracting best results from the motor. Moreover, they can able to operate with reduced switching frequency that certainly reduces switching losses. Still, the increased voltage levels comprise a higher number of power semiconductor switches, cumulative voltage stress and switching losses are making the system more complicated. In this paper an innovative seven-level inverter with five switches had been taken to investigate 0.5 H. P single phase induction motor water pump. This topology ensures minimum switching losses, lowering size along with less installation cost. In order to provide better insight into the working and performance of this proposed topology the simulation results performed in the MATLAB / Simulink environment and hardware implementation are depicted.

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Investigation of Standalone Solar Photovoltaic Water Pumping System With Reduced Switch Multilevel Inverter

A new concept in control of cascaded H-Bridge multi-level inverters is proposed in this paper. According to this concept, switching angles are considered to be independent from the fundamental voltage. A polynomial term is presented to show the relation between switching angles and DC voltages. Based on this concept, Total Harmonic Distortion (THD) calculations are updated and proved to be independent from the fundamental voltage. Thus, once calculated for minimum THD, the switching pattern can be used for any required level of output voltage. To examine the effectiveness of the proposed method, it is applied in control of an eleven level inverter. The simulation results are demonstrated and verified through experiments with a setup controlled by Xilinx SPARTAN3 family FPGA (XC3S400-PQG208).

https://www.ejece.org/index.php/ejece/article/download/58/44

T. Poompavai

Papers

Comparative analysis of modified multilevel DC link inverter with conventional cascaded multilevel inverter fed induction motor drive