CFD Modelling of a Pump as Turbine (PAT) with Rounded Leading Edge Impellers for Micro Hydro Systems

A Pump as Turbine (PAT) is one of micro hydro system components that is used to substitute a commercially available turbine due to its wide availability and low acquisition cost. However, PAT have high hydraulic losses due to differences in pumpturbine operation and hydraulic design. The fluid flowing inside the PAT is subjected to hydraulic losses due to the longer flow passage and unmatched fluid flow within the wall boundaries. This paper presents the effect of rounding the impeller leading edges of the pump on turbine performance. A CFD model of a PAT was designed to simulate virtual performance for the analysis. The aim of this study is to observe the internal hydraulic performance resulting from the changes in the performance characteristics. Highest efficiency was recorded at 17.0 l/s, an increase of 0.18%. The simulation results reveal that there is an improvement in hydraulic performance at overflow operation. The velocity vector visualization shows that there is a reduction in wake and consequently less flow separation along impeller flow passages. However, adjusting the sensitive impeller inlet geometry will also alter the velocity inlet vector and consequently change the velocity triangles for the turbo machinery system

Development and Modelling of Three Phase Inverter for Harmonic Improvement using Sinusoidal Pulse Width Modulation (SPWM) Control Technique

This paper describes the design of a 400 V, three-phase voltage source inverter system using Sinusoidal Pulse Width Modulation (SPWM) control technique. Pulse Width Modulation (PWM) is an internal control technique for inverters. The Sinusoidal Pulse Width Modulation (SPWM) technique is the type of PWM used in this work. The aim is to reduce the harmonic produced by the inverter. Current standards require that total harmonic distortion (THD) be minimal. A three-phase SPWM signal is implemented in order to create an output voltage which is closer to a true sine wave and reduce harmonics. The development and model were implemented using MATLAB Simulink soft-ware and hardware parameters. The addition of a low pass filter circuit aids the achievement of smoother sine waveforms and a reduced THD value of 0.17%. The proposed concept has been validated through experimentally on a laboratory prototype by using DSP TMS320F28335 real-time digital control. The experimental outcomes emphasize the authenticity of the suggested technique in reducing harmonics, which can be promising to power quality improvement

Active Cell Balancing Control Method for Series-Connected Lithium-Ion Battery

Power conveyance potentiality for series and parallel allied battery-packages are constrained by the wickedest cell of the string. Every cell contains marginally dissimilar capability and terminal voltage because of industrialized acceptances and functional situations. During charging or discharging progression, the charge status of the cell strings become imbalanced and incline to loss equalization. Therefore, the enthusiasm of this paper is to design an active charge balancing system for Lithium-ion battery pack with the help of online state of charge (SOC) estimation technique. A Battery Management System (BMS) is modeled by means of controlling the SOC of the cells to upsurge the efficacy of rechargeable batteries. The capacity of each cell is calculated by dint of SOC function estimated as a result of Backpropagation Neural Network (BPNN) algorithm through four switched DC/DC Buck-Boost converter. The simulation results confirm that the designed BMS can synchronize the cell equalization via curtailing the SOC estimation error (RMSE 1.20%) productively

Design and Implementation of a Voltage Tracking with Artificial Neural Network Controller for a Double-input Buck-Boost Converter

This paper proposes an Artificial Neural Network (ANN) control voltage tracking scheme of a double-input buckboost DC-DC converter. In this topology, a back-propagation algorithm topology is implemented. The controller is developed to improve the performance of the double-input converter during transient and steady-state operations. The neural network controller design, which is developed against output voltage command tracking is proposed. The proposed concept has been investigated and validated experimentally on a laboratory prototype using DSP TMS320F28335real time digital controller to verify the dynamic response of the proposed controller. The experimental results confirm the validity of the proposed neural network control technique, which is a promising an efficient control topology that ensures doubleinput converter suitable for electric vehicle and renewable energy applications

Clustered Coordinator SABTS (CC-SABTS) for Beacon Transmission in IEEE802.15.4 LR-WPAN

IEEE802.15.4 standard for Wireless Sensor Network (WSN) provides low-power transmission in the low-rate wireless personal area network (WPAN). It has three types of topology: star, peer-to-peer and cluster tree. Star topology has limit to expand network. Peer-to-peer topology has a complex multihop routing during network expansion due to the large number of full-function devices. A full-function device can act as coordinator and personal area network coordinator (PAN-C). Cluster tree topology is preferable because it can expand networks using less number of full-function devices and thus reduces complexity in routing messages. A cluster tree topology consists of a wireless PAN-C, several cluster coordinators and a number of end devices. The coordinators periodically transmit beacon frames to one another to allow synchronization and communication. However, collision will happen if the coordinators transmit beacon frames at the same time and will degrade the network performance. Different mechanisms have been introduced to solve the collision problem and one of the mechanisms is superframe adjustment and beacon transmission scheme (SABTS). SABTS calculates the precise time for beacon transmission by assigning an accurate value of beacon order and superframe order for PAN-C, cluster coordinators and end devices. As the number of cluster coordinator increases, SABTS method reiterates the calculation for beacon transmission time numerously. Hence, in order to decrease the iteration, this paper introduces clustered coordinator SABTS (CC-SABTS) by clustering coordinator nodes that are separated by two length radius. The performance of CC-SABTS is simulated and evaluated using NS2 simulation software. Result shows that CC-SABTS provides better average throughput, packet delivery ratio and end-to-end delay compared to the conventional SABTS

Contingency Analysis of a Power Grid with the Participation of Utility-Scale Solar PV Units: A Case Study from Sarawak, Malaysia

Integrating renewable energy resources (RER) into the power grid may jeopardize the whole power system if the penetration level or solar PV uncertainty is not thoroughly managed. The critical impact on the behaviour of power system can be observed during the line outage in a power grid connected with large-scale RER. Therefore, contingency analysis (CA) is crucial to assess such hybrid power grid. This paper proposes a framework based on CA to assess the simultaneous effect of large-scale solar photovoltaic (PV) power plants integrated with the existing power grid, particularly, in the aspects of implementing effective measuring indices. Simulation studies have been carried out on a practical power system, which was modelled by considering the probability of solar irradiance at different locations in Sarawak. The study presented in this paper can provide an insight to identify the level of insecurity for a large-scale deployment of solar PV systems in Sarawak

A battery integrated multiple input DC-DC boost converter

In this paper, the proposed single boost converter aims to harness more than one renewable energy (RE) input source and achieve a high voltage gain. The interleaved technique combined with voltage multiplier (VM) cells, reduced inductor current and attained high voltage transfer ratio. The boost converter possesses two unidirectional input ports and a bidirectional input port that is connected to a battery storage. The duty ratios of the power and interleaving switches are used to regulate the output voltage of the proposed converter. Three operation modes are identified, and steady state analyses of the converter are presented and discussed. The converter can store excess energy in the battery during periods of abundance and deliver power to the loads when the RE sources are low or unavailable. In addition, the output voltage is higher than that of the conventional boost converter. The converter delivered 278 V from 12 V and 24 V dual input sources. The converter operation is simulated and verified using MATLAB/Simulink

Sizing of a Hybrid Photovoltaic-Hydrokinetic Turbine Renewable Energy System in East Malaysia

The difficulties faced in the extension of conventional grid electricity to remote locations elicit increased application of renewable energy (RE) sources in such locations. In locations that are in proximity to rivers or streams, microhydro hybrid RE systems (HRES) are employed. Similarly, hybrid photovoltaic (PV) /battery configurations exist. Unfortunately, micro-hydro turbines require a minimum height/head and expensive civil works during installation. Hydrokinetic turbines (HKTs) eliminate the height/head requirement and greatly reduce necessary civil work by generating electricity using the kinetic energy of water flow in a river or stream. This study used a software, Hybrid Optimization of Multiple Energy Resources (HOMER), to simulate and obtain the optimal size and configuration of a hybrid PV/HKT/Battery storage system for Kampung Git in East Malaysia. Techno-economic comparison of the system is done with a PV/Battery and a standalone diesel generator (DG) system. The levelized cost of energy (LCOE) and the total net present cost (NPC) are the primary indices used for comparison purposes. The optimal configuration from simulations has 89.9 kWp of PV, two 3.5 kW HKTs and 132 kWh of battery storage. Also, economic results obtained indicate that the LCOE of 1.21 RM/kWh and NPC of RM 1,431,000 for the PV-HKT-battery configuration bested those for the PV-battery and standalone DG systems by 165 % and 27 % respectively. This optimal configuration is more environmentally friendly and highlights the role of the HKT in reducing battery usage and wear in addition to achieving lower LCOE and NPC values