Multilevel Three Phase Voltage Source Inverter With Simple Space Vector Pulse Width Modulation

Multilevel inverter has brought a great revolution in many industrial applications. The performances of multilevel inverter depend on the suitable modulation technique and topology. There a number of modulation techniques and topologies are already developed during last three decades. The most popular multilevel inverter topology is cascaded h-bridge inverter due to not having any clamping diode or capacitor and better performances. But it requires several number of separated DC sources that increase complexity as well as system cost. Three phase cascaded multilevel inverters with reduced number of DC voltage sources are proposed in this research that requires only 2, 3, 4, 5 and 6 separated DC sources for three phase 3, 4, 5, 6 and 7-level. Three phase cascaded multilevel inverters with single DC voltage source are also proposed in this research. On the other hand, the most popular modulation technique is space vector pulse width modulation (SVPWM) because of their easier digital realization, over modulation, high switching frequency, better DC bus utilization and lower THD. The complexity of switching control algorithms for multilevel inverter is increasing with the number of level due to increasing the number of switching states in space vector diagram. This research simplifies the space vector diagram that reduces the switching states to 26 from 27, 56 from 64, 98 from 125, 152 from 216 and 218 from 343 for 3, 4, 5, 6 and 7-level SVPWM respectively. The simplified strategy used in the research, the lower weighted digit values of switching states are omitted because performance of the multilevel inverter depends on the more weighted digit value of switching states. However it still has a constraint of having different number of switching states for different sub switching triangle of each sector. Therefore, the best four different active switching states will be selected for each switching triangle that makes the overall PWM algorithm simpler. The proposed three phase cascaded multilevel inverters (CMLI) based on simple space vector pulse width modulation have been modeled, simulated and evaluated using MATLAB/SIMULINK. Simulation results based on the proposed technique demonstrated the significant improvement in terms of output voltage and THD. The inverters of each level have been implemented using a single eZdsp control board embedded with TMS320F2812 processor. The results obtained from the experimental investigation for 3, 4, 5, 6 and 7 level inverter are consistent with the results obtained from the simulation. The three phase 7-level CMLI demonstrated 10.69% THD that is closest the IEE519 standard of 10% THD

A green Economy in the Context of Sustainable Development and Poverty Eradication: What are the Implications for Bangladesh?

This paper justifies the necessitate for interpretive forms of economic study and then deals with their practical application in Bangladesh.               At present green economy is the burning issue in Bangladesh. To create awareness and provide information about green economics this is the main theme of this paper. Convincing evidence for policymakers and business leaders to supply in clean technologies, renewable energy and natural infrastructure will be presented in the Green Economy Report (GER), a ground-breaking study being conducted as part of the Green Economy Initiative. Sustainable development has been the overarching goal of the international community since the UN Conference on Environment and Development (UNCED) in 1992. Amongst numerous commitments, the Conference called upon governments to develop national strategies for sustainable development, incorporating policy measures outlined in the Rio Declaration and Agenda 21. Despite the efforts of many governments around the world to implement such strategies as well as international cooperation to support national governments, there are continuing concerns over global economic and environmental developments in many countries. These have been intensified by recent prolonged global energy, food and financial crises, and underscored by continued warnings from global scientists that society is in danger of transgressing a number of planetary boundaries or ecological limits.   Keywords: Green Economy, Sustainable development, Poverty Eradicatio

Industrial IoT based condition monitoring for wind energy conversion system

Wind energy has been identified as the second dominating source in the world renewable energy generation after hydropower. Conversion and distribution of wind energy has brought technology revolution by developing the advanced wind energy conversion system (WECS) including multilevel inverters (MLIs). The conventional rectifier produces ripples in their output waveforms while the MLI suffers from voltage balancing issues across the DC-link capacitor. This paper proposes a simplified proportional integral (PI)-based space vector pulse width modulation (SVPWM) to minimize the output waveform ripples, resolve the voltage balancing issue and produce better-quality output waveforms. WECS experiences various types of faults particularly in the DC-link capacitor and switching devices of the power converter. These faults, if not detected and rectified at an early stage, may lead to catastrophic failures to the WECS and continuity of the power supply. This paper proposes a new algorithm embedded in the proposed PI-based SVPWM controller to identify the fault location in the power converter in real time. Since most wind power plants are located in remote areas or offshore, WECS condition monitoring needs to be developed over the internet of things (IoT) to ensure system reliability. In this paper, an industrial IoT algorithm with an associated hardware prototype is proposed to monitor the condition of WECS in the real-time environment. © 2015 CSEE

Effectiveness of scapular mobilization to reduce shoulder pain among the patients with Spinal Cord Injury

Background: Patients with Spinal Cord Injury often experience debilitating shoulder pain. This study investigates the effectiveness of scapular mobilization as a potential intervention to alleviate this pain and enhance the quality of life for these individuals.Objectives: The objectives were to identify the effectiveness of scapular mobilization in reducing shoulder pain among patients with spinal cord injury. Methodology:Pretest and posttest designs were used to conduct this study. 16 participants were selected according to inclusion criteria. The 'VAS' and 'Goniometer' were used to assess the shoulder pain and joint range of motion (ROM). Analysis was done through SPSS v22. To analyze the pre-post test data, the Wilcoxon signed-rank test was used. Result: Among 16 participants, the mean age was 27.69 with a standard deviation of ±11.5, median 27, mode 18, maximum age 52, minimum age 13. Male participants were predominantly higher than female participants. Out of the 16 participants, 93.8% (n=15) were male, and 6.3% (n=1) were female. Among them, 50% (n=8) of the participants were caused to fall from a height, 37% (n=6) were caused by a road traffic accident, and 12.5% (n=2) were caused by heavy objects falling on them. The most significant neurological level was T12, with a percentage of 31.3%, while 25% were at L1, and 12.4% were at T7 and T11, respectively. The right-sided shoulder joint was affected in 43.75% of cases, the left-sided in 31.25%, and 25% were affected on both sides. In the statistical analysis, there was a significant improvement in shoulder pain reduction, shoulder flexion, and extension.Conclusion:Overall, this dissertation showed that scapular mobilization was more dominant than only conventional physiotherapy in reducing shoulder pain and improving shoulder movement

Recent Progress and Future Trends on State of Charge Estimation Methods to Improve Battery-Storage Efficiency : A Review

Battery storage systems are subject to frequent charging/discharging cycles which reduce the operational life of the battery and reduce system reliability on the long run. As such, several Battery Management Systems (BMS) have been developed to maintain system reliability and extend the battery's operative life. Accurate estimation of the battery State of Charge (SOC) is a key challenge in the BMS due to its non-linear characteristics. This paper presents a comprehensive review on the most recent classifications and mathematical models of the SOC estimation. Future trends of the SOC estimation methods are also presented

Active Charge Balancing Strategy Using the State of Charge Estimation Technique for a PV-Battery Hybrid System

: Charging a group of series-connected batteries of a PV-battery hybrid system exhibits an imbalance issue. Such imbalance has severe consequences on the battery activation function and the maintenance cost of the entire system. Therefore, this paper proposes an active battery balancing technique for a PV-battery integrated system to improve its performance and lifespan. Battery state of charge (SOC) estimation based on the backpropagation neural network (BPNN) technique is utilized to check the charge condition of the storage system. The developed battery management system (BMS) receives the SOC estimation of the individual batteries and issues control signal to the DC/DC Buck-boost converter to balance the charge status of the connected group of batteries. Simulation and experimental results using MATLAB-ATMega2560 interfacing system reveal the effectiveness of the proposed approac

Cost-Effective Design of IoT-Based Smart Household Distribution System

The Internet of Things (IoT) plays an indispensable role in present-day household electricity management. Nevertheless, practical development of cost-effective intelligent condition monitoring, protection, and control techniques for household distribution systems is still a challenging task. This paper is taking one step forward into a practical implementation of such techniques by developing an IoT Smart Household Distribution Board (ISHDB) to monitor and control various household smart appliances. The main function of the developed ISHDB is collecting and storing voltage, current, and power data and presenting them in a user-friendly way. The performance of the developed system is investigated under various residential electrical loads of different energy consumption profiles. In this regard, an Arduino-based working prototype is employed to gather the collected data into the ThingSpeak cloud through a Wi-Fi medium. Blynk mobile application is also implemented to facilitate real-time monitoring by individual consumers. Microprocessor technology is adopted to automate the process, and reduce hardware size and cost. Experimental results show that the developed system can be used effectively for real-time home energy management. It can also be used to detect any abnormal performance of the electrical appliances in real-time through monitoring their individual current and voltage waveforms. A comparison of the developed system and other existing techniques reveals the superiority of the proposed method in terms of the implementation cost and execution time

An Intelligent Controlling Method for Battery Lifetime Increment Using State of Charge Estimation in PV-Battery Hybrid System

In a photovoltaic (PV)-battery integrated system, the battery undergoes frequent charging and discharging cycles that reduces its operational life and affects its performance considerably. As such, an intelligent power control approach for a PV-battery standalone system is proposed in this paper to improve the reliability of the battery along its operational life. The proposed control strategy works in two regulatory modes: maximum power point tracking (MPPT) mode and battery management system (BMS) mode. The novel controller tracks and harvests the maximum available power from the solar cells under different atmospheric conditions via MPPT scheme. On the other hand, the state of charge (SOC) estimation technique is developed using backpropagation neural network (BPNN) algorithm under BMS mode to manage the operation of the battery storage during charging, discharging, and islanding approaches to prolong the battery lifetime. A case study is demonstrated to confirm the effectiveness of the proposed scheme which shows only 0.082% error for real-world applications. The study discloses that the projected BMS control strategy satisfies the battery-lifetime objective for off-grid PV-battery hybrid systems by avoiding the over-charging and deep-discharging disturbances significantl

Monitoring of renewable energy systems by IoT‐aided SCADA system

With the rapid increase of renewable energy generation worldwide, real‐time information has become essential to manage such assets, especially for systems installed offshore and in remote areas. To date, there is no cost‐effective condition monitoring technique that can assess the state of renewable energy sources in real‐time and provide suitable asset management decisions to optimize the utilization of such valuable assets and avoid any full or partial blackout due to unexpected faults. Based on the Internet of Things scheme, this paper represents a new application for the Supervisory Control and Data Acquisition (SCADA) system to monitor a hybrid system comprising photovoltaic, wind, and battery energy storage systems. Electrical parameters such as voltage, current, and power are monitored in real‐time via the ThingSpeak website. Network operators can control components of the hybrid power system remotely by the proposed SCADA system. The SCADA system is interfaced with the Matlab/Simulink software tool through KEPServerEX client. For cost‐effective design, low‐cost electronic components and Arduino Integrated Development Environment ATMega2560 remote terminal unit are employed to develop a hardware prototype for experimental analysis. Simulation and experimental results attest to the feasibility of the proposed system. Compared with other existing techniques, the developed system features advantages in terms of reliability and cost‐effectivenes

Control of a Multilevel Inverter for Wind Energy Conversion System with Energy Storage and Condition Monitoring Options

A generalized three-phase cascaded multilevel inverter (CMLI) is proposed which requires four non-isolated series-connected dc-link capacitors only. A simplified space vector pulse width modulation (SVPWM) controller is proposed to control the three-phase CMLI, to balance and minimize the ripples of dc-link voltages. In addition, algorithms are proposed to monitor the condition of dc-link capacitors and switching devices in real-time remotely over internet. Three-phase CMLI, simplified SVPWM, and algorithms have been tested through simulation and experiment