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The number of DGs located at distribution site, which uses renewable energy sources, forms a Micro-grid system. The problem of using DG with the utility is unplanned islanding. This paper has focus...

Islanding of Microgrid is important in case of grid disconnection. There are various methods of islanding in which passive islanding methods are easy to implement but have large non detection zone (NDZ). The majority of the islanding methods are tested on single phase PV– grid connected system. Very few methods were studied for the multi DG systems. In this paper, passive and active islanding detection methods (IDM) are presented when measurements are carried out at point of common coupling (PCC) when two DGs are linked in parallel. Additionally a new technique is projected here for islanding in which recursive least square algorithm (RLS) is applied for measuring the frequency of active frequency drift (AFD) current. Further comparative analysis is done for active frequency drifts (AFD) with the new proposed method on multi DG system connected to the grid. A change in the distorted frequency generates the tripping signal, in fast manner as compare to AFD. The simulation results are reported based on MATLAB software. The analysis shows that estimation of frequency for current of AFD with RLS approach is more suitable for islanding.

Multilevel Inverters are now increasingly used in most of the power electronics applications including medium and high voltage devices. SHE is useful for eliminating the switching losses particularly for high voltage applications. This paper presents selective harmonic elimination through Hybrid optimization algorithm for elimination of lower order odd harmonics and THD in the multilevel inverter output. This hybrid algorithm is a combination of Ant colony optimization and Newton-Raphson algorithm where ant Colony optimization algorithm is applied for first four cycles and then the output of this algorithm will be treated as a starting consideration for N- _R algorithm. The primary advantage of this algorithm is its simplicity of design, less computational efforts, faster convergence and elimination of need of initial guess compared to other conventional iterative methods. Results show that third, fifth and seventh harmonics along with THD are minimized greatly. MATLAB/Simulink software is used to simulate these results. Experimental results are also presented to prove the efficacy of proposed system.

A Belt Weigh Feeder (BWF) is a flat belt conveyor designed for feeding bulk material into a chemical process in a controlled fashion for better process control. The dynamic weight of bulk material is measured with a belt weigh bridge and the belt speed is controlled to compensate for any variation in the weight so that the mass feed rate is maintained as per the set feed rate. The problem of belt speed control is challenging as the dynamic response of system is non-linear and there are frequent changes in belt load due to variation in bulk material characteristics. The control accuracy of belt weigh feeder is fully dependent on the controller’s performance in providing precise control of speed of motor/belt. Any delay in achieving the set feed rate or frequent deviation between set and actual feed rate affects the quality and efficiency of downstream process. Conventional PI controller is unable to provide optimum control due to system non-linearity. To overcome this problem, in this paper first the operating data of the BWF system is analysed and the nature and cause for the nonlinearity is investigated. The system is then modelled using the design parameters of plant belt weigh feeder, which is then simulated to have a better insight into its non-linear response. Subsequently, based on simulation results, a PI Fuzzy Logic (PI-FL) controller is designed to improve the control accuracy of the system. Further, to ensure the stability of the system, an adaptive controller is introduced in cascade to fine tune the gains of PI-FL controller as per the operating speed of the BWF. Finally, an advanced PI-FL with cascade adaptive controller is implemented in the plant DCS (microprocessor based process control system). The actual test results indicate reduction in the Integral of Absolute Error (IAE) of the system by about 34% using this controller.

This paper presents, ant colony optimization based hybrid algorithm for selective harmonic elimination in single phase seven level multilevel inverter with reduced switches. For high power and high voltage applications, multilevel structure with selective harmonic elimination (SHE) modulation scheme is used. The output voltage of multilevel inverter contains fundamental component along with harmonics. SHE technique aims to solve non-linear transcendental equations maintaining the fundamental harmonic component to its desired value and to eliminate lower order odd harmonics. Many optimization algorithms have been implemented to solve this problem. But these algorithms are complicated and time consuming. The Newton–Raphson algorithm is also very convergent for solving these non-linear equations. The main disadvantage of this method is, it requires strong initial guess. To overcome these drawbacks, hybrid optimization algorithm is used in this paper. This algorithm is performed in two stages, during first stage ant colony optimization has been run and in second stage the solutions obtained from ACO is used as a initial guess for Newton–Raphson algorithm which confirms the exact converged solution. Thus the drawback of Newton’s method i.e. requirement of good initial guess is overcomed by proposed hybrid algorithm. The MATLAB/SlMULINK software is used for comprehensive simulation of seven-level inverter. Experimental results validate the simulated results.

Now a day, distributed sources are emerging widely due to their advantages owing to renewable-based power generation. In this paper, a novel passive islanding method for the inverter-based ...

This paper presents the multilevel inverter (MLI) based Electric spring (ES) for smart grid applications. Due to the superior performance of Diode-clamped MLI (DCMLI) over other MLI topologies, in this paper ES is realized using 5-level DCMLI. Further the performance of two-level and five-level DCMLI based ES is investigated in terms of Total Harmonic Distortion (THD). It is ascertained that five- level DCMLI achieves voltage regulation with lesser THD in compensated voltage. Moreover, the use of DCMLI based ES as a distributed source is also elaborated. To extract the digitally simulated results and to validate system performance of MLI based ES, detailed simulation studies are carried out using MATLAB environment.

This paper presents a control scheme for variable speed wind energy conversion system (WECS) using permanent magnet synchronous generator (PMSG). The control scheme extracts maximum power from wind using maximum power point tracking (MPPT) technique. In this paper, the proposed control scheme is achieved using two back-to-back voltage source converters (VSC) with the DC-link whose voltage is to be maintained. The control scheme discussed in this paper is zero direct-axis current (ZDC) control where the d-axis stator current is kept zero. Performance evaluation of the system is carried out and detail simulation results are demonstrated using MATLAB/SIMULINK environment. The simulation results proves the effectiveness of application of the ZDC control for variable speed WECS.

The grid connected inverters are increasingly used nowadays in distributed generation and smart grid. But the main challenge in grid connected systems is their compatibility with grid utility and also to maintain the harmonic contents of output current. To overcome these challenges, different current control techniques are used so far. This paper presents a multilevel inverter for single phase grid connected system. The switching of the inverter is based on Selective Harmonic Elimination PWM method where switching angles are calculated by Newton Raphson (NR) method. The main objective is to inject power in to the grid, to reduce the harmonics of grid current and to synchronise the grid frequency with inverter frequency. The results are verified through MATLAB/Simulink and experimentally using low cost microcontroller.

Integration of solar photovoltaic (PV) panels with existing utilities requires effectively controlled converters. While developing and testing such converters, it is difficult to test them with actually installed PV panels owing to unavailability of practical onsite conditions for all the time. For such cases, PV simulators are preferred, which are required to exhibit PV system behavior under working conditions without the use of real outdoor installation. This reduces the time and cost of experimentation. In this paper, a real-time PV simulator based on a dc–dc buck converter is investigated to obtain true PV characteristics. The practical difficulty with PV simulators is that they often get oscillations in the constant current region or constant voltage region of PV characteristics, particularly when the controller is designed using a low-cost digital controller. This paper introduces a novel hysteresis controller to ensure effective operation in both these regions. This dual control strategy ensures effective control in both regions and provides smooth trajectories as per mathematical model or lookup table to mimic any PV characteristics under various temperatures and insolations with the use of the low-cost digital controller. The hardware prototype is constructed with the digital signal controller to demonstrate the efficacy of the proposed simulator.

Total harmonic distortion, produced with the existing PWM techniques for a Z-source inverter topology, is higher due to the unsymmetrical shoot-through, if separate controls of ac and dc sides are required. This paper proposes the concept of symmetrical shoot-through-based modulation and compares the performance with the case of the popular simple boost control. The proposed modulation method achieves a sinusoidal and symmetrical distribution of shoot-through states. This ensures an improved current and voltage profile at the output, along with the capability of decoupled control for the shoot-through and the modulation index control. The effectiveness of the proposed method has been demonstrated and validated through analysis, simulation, and experimentation. This concept can be applied to all the variants of Z-source-based power conversions.

Quasi-Z-source inverters (qZSIs) are nowadays increasingly used owing to advantages such as single-stage operation, lower component rating, and continuous input current and common dc rail. These benefits lead to investigate this converter for grid-connected applications. This paper presents a grid-connected qZSI with both ac and dc side control. Sliding mode control (SMC)-based controller for capacitor voltage regulation has been proposed to ensure a fast and dynamic response for wide variations in input voltage, output load, and reference controlled quantity. A detailed mathematical model of the system is presented. A stable and fast response of SMC has been demonstrated using simulation and is validated by experimental results.

Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System (WECS) is highly preferred these days with back-to-back converter topologies. In order to overcome the sudden converter failure problems, to reduce DC-link rating and for continuity of power supply to the grid; this paper proposes variable speed WECS using PMSG with parallel back-to-back converters with separate DC-links. In both the converter strings the generator-side converters are controlled by using separate Zero Direct-axis Current (ZDC) control with Optimal Torque Control (OTC) technique for Maximum Power Point Tracking (MPPT) and both the grid-side converters are controlled with the help of separate grid-side control. In addition, the problem of zero sequence circulating current has been taken into account. The proposed scheme is been implemented using the MATLAB environment and the overall performance of the system is evaluated through experimental studies.

In present era to meet the increasing load demand there is integration of intermittent Renewable Energy Sources (RES) in the power sector. The penetration of these clean energy sources causes voltage instability, frequency fluctuation and propagation of harmonics in the system. This paper presents Electric Spring (ES) to suppress the harmonics caused by the non-linear critical load. Basically Electric Spring is a current controlled voltage source with Voltage Source Inverter (VSI) as a basic building block. To switch the inverter current controlled techniques are used. Therefore, this paper proposes Modified Space Vector based Hysteresis Current controller (SVM-HCC) for Electric Spring applications in smart grid to achieve constancy in switching frequency. The proposed technique capitalized on the combined advantages of both Space Vector Modulation (SVM) and Hysteresis Current Control (HCC) techniques. Simulation results are obtained using MATLAB environment are used to demonstrate the advantages of Modified Hysteresis Controller compared to Conventional Hysteresis Controller to achieve constancy switching frequency.

Looking towards the current power scenario, it is observed that the use of distributed generation (DG) is spread widely. Micro-grid consists of the number of DG unit located at distribution site and in present days most of them uses nonconventional energy sources. But the problem which has to solve while using DG with utility is unintentional islanding as it is hazardous to power system equipment and workers life. In this paper comparative analysis of rate of change of frequency (ROCOF) ripple and voltage ripple based passive islanding detection method (IDM) has been done for single-phase utility connected micro-grid system. The proposed methods are verified under a wide range of operating condition of islanding and nonislanding in MATLAB/SIMULINK software. Both the proposed techniques are accurate, and overcome the limitations of conventional passive islanding method. The proposed methods are also capable of distinguishing islanding and non-islanding condition. The voltage ripple based passive IDM is faster than ROCOF ripple based IDM and other conventional methods.

This study aims to propose a control which is a combination of model predictive control (MPC) and hysteresis current control (HCC) referred as hysteresis-based predictive control. Similar to MPC, the system model is incorporated and used to determine predicted compensator currents without considering cost function. Further, these currents are compared with the reference currents extracted using instantaneous symmetrical component theory to generate switching for inverter. The control provides nearly constant switching frequency of neutral-point-clamped (NPC) inverter in distributed static compensator applications. The method employs possible voltage vectors to obtain output current predictions. The zero tracking error is verified using validating condition (quality function) to ensure the proper current predictions. Further, by controlling the uncontrolled states and selecting maximum ON time with symmetrical switching sequence, nearly constant switching frequency is obtained. The performance of the proposed current control is compared with HCC and MPC and the remarkable improvement in terms of tracking; reduced current error bandwidth; reduced and constant switching frequency and load compensation are presented. Moreover, the theoretical and analytical comparisons are carried out to demonstrate the superiority of the proposed control. An extensive simulation and programming are carried out using MATLAB to extract the simulated results and validated through experimental studies.

From last two decades owing to drastic rise in industrialization and modernization the generated power by conventional energy sources are insufficient to meet the increasing power demand. In order to overcome this major problem Non-conventional energy sources are penetrating in the power grid. The integration of these Non-Conventional energy sources causes fluctuations in the voltage and power of the entire grid. “Electric Spring” (ES)is a neoteric reactive power compensator, used to compensate the voltage and power of the grid. The heart of the Electric Spring is voltage source inverter(VSI). In order to switch the inverter different pulse width modulation(PWM)techniques are used. Considering, the attractive feature of space vector pulse width modulation technique(SVPWM)over other voltage controlled PWM schemes, this paper proposes an effective structure of space vector based Electric Spring with a huge potential in regulating the Alternating Current(AC)mains voltage, despite of the penetration of N on-Conventional energy sources. Also, the operation of Electric Spring in different operating modes are discussed. Further the paper describes a detailed comparison of Sinusoidal Pulse Width Modulation technique(SPWM)with Space Vector Pulse Width Modulation (SVPWM)for stabilizing the voltage and compensating the reactive power in the grid. The dynamic performance of the proposed structure of Space Vector based Electric Spring has been tested and demonstrated through detailed MATLAB simulation and validated using Experimental studies.

Multi DG microgrid has evolved as a reliable and cost-effective solution for smart grid applications. Quasi impedance source inverter (qZSI) has emerged as an effective converter for grid-tied inverter systems. In this paper active power sharing control of two DG hybrid system using qZSI is designed for synchronisation with the microgrid. The primary advantage of the proposed scheme is that the need of additional power-sharing inductor in the conventional method is eliminated and filter inductor is taking care of the circulating current. The proposed SST-PWM based controller can be effectively used in hybrid systems with two or more numbers of sources like PV arrays, wind energy conversion system, fuel cell, biomass plant etc. The simulation results are carried out in MATLAB. This control strategy can be used for increasing the efficiency of the overall system of active power sharing.

The Electric Spring (ES) has been introduced as an advanced strategy to achieve equilibrium between power generation and consumption. For taming the erratic nature of renewable energy sources (RES), this paper provides the analysis of the three different configurations of ES. In this paper, the work is focused on the performance comparison of the three different versions of ES namely ES-1, ES-2 and Back-to Back ES (ES-B2B). The structure of different configuration is also explained. For a known span of the voltage deviation the quantity requirement for all configurations to provide the required voltage compensation is compared. It turns out that the ES-B2B configuration is highly effective in achieving the voltage regulation than the other two configurations of ES. The ES-2 configuration overcomes the limitation of ES-1 whereas ES-B2B configuration broadens the operating capability of ES-1. Also, multilevel inverter based ES configuration is simulated to demonstrate the feasibility of multilevel inverter and use of multiple ES in the grid. The performances of different configurations and their controls are discussed, while their comprehensive comparative evaluations are done using MATLAB environment.

The increasing demand of efficiency, cost effectiveness, environmental aspects has driven the development of micro grid technology. The controlling of the micro grid in standalone mode and grid connected mode is the major concern. The active power sharing after grid disconnection and resynchronization with the utility grid are the challenging task in micro grid. In this paper, proper relay coordination are proposed for islanding and power sharing of multi distribution generations (DGs) unit in single phase system. Also discussed the synchronization of DGs with utility grid using Static Transfer Switch (STS) called as micro switch. Various conditions consider for islanding, active power sharing of multi DGs and synchronization between grid with two parallel connected DG's. The simulation results reported in this paper are based on MATLAB software. Result shows that Static transfer switch works effectively and synchronized the system in proper way.

Application of Particle Swarm Optimization algorithm for finding the optimal solution of switching angles in a 3-ph seven level Cascaded Multilevel Inverter (CMLI) with unequal DC sources for elimination of lower order harmonics is presented in this paper. For Cascaded Multilevel Inverter, the common switching technologies such as low frequency Selective Harmonic Elimination-Pulse Width Modulation (SHE-PWM) technique and Optimal Minimization of Total Harmonic Distortion (OMTHD) techniques are applied to obtain staircase voltage waveform. SHE-PWM based approach is used to maintain desired fundamental component of output voltage and to reduce specific lower order odd harmonics. Whereas OMTHD is used to minimize the overall THD. The lower order odd harmonics cannot be eliminated easily as it contains non linear transcendental equations derived from Fourier series expansion. Solutions to these equations are complex and time consuming. In this paper, to solve these nonlinear equations PSO algorithm has been implemented. Simulation of seven level CMLI with unequal DC sources with proposed algorithm in MATLAB/Simulink environment is performed to validate the results.

Electric Spring is new emerging technology for stabilizing future smart grid. Due to integration of renewable energy sources with conventional one, new technological problem arises causing voltage instability in power grid. Electric spring is device which is effective in stabilizing voltage of system in decentralized manner and is more reliable over centralized way. Electric Spring is implemented earlier with using two level inverter, but this paper focused on implementation of Electric Spring using a special type of multilevel inverter i.e. NPC/H Bridge inverter. NPC/H Bridge inverter is further extension of Neutral point clamped inverter (NPC) and show additional effective features over NPC. Simulation is carried out using MATLAB/SIMULINK sucessfully showing comparision of Two-level, Three-level cascaded and Five-level NPC/H-bridge inverter THD's (Total Hormonic Distortion). ES based NPC/H bridge inverter successfully provides superior high frequency harmonic suppression along with improved system THD profile and effective voltage regulation.

A belt weigh feeder system is an electro-mechanical system consisting of variable speed flat belt conveyor designed for feeding bulk material in the process in a controlled fashion. The dynamic weight of bulk material on the belt is measured with a belt weigh bridge and the belt speed is controlled to compensate for the variation in weight so that the feed rate is maintained constant. The problem of belt speed control is challenging as the dynamic response of system is nonlinear and there are frequent changes in belt load due to variation in bulk material characteristics. The control accuracy of belt weigh feeder is fully dependent on the controller performance in providing precise control of speed of motor/belt. Any delay in achieving the set feed rate or frequent deviation between set and actual feed rate affects the quality and efficiency of downstream process. Conventional PI controller is unable to provide optimum control due to system nonlinearity. To tackle these problems, first the system is modeled and rigorously simulated in open and closed loop to have a better insight into its nonlinear response. Subsequently, PI Fuzzy Logic controller is designed for control of belt weigh feeder. The results indicate substantial improvement in control accuracy of the system with PI Fuzzy Logic controller.

This paper proposes “Electric Spring” (ES) based on Single Phase three-level Cascaded H-Bridge Inverter to achieve effective demand side management for stabilizing smart grid fed by substantial intermittent renewable energy sources (RES). Considering the most attractive features of multilevel inverter (MLI), an effective structure of Electric Spring is proposed for suppressing voltage fluctuation in power distribution network arising due to RES and maintaining the critical load voltage. Also, the operation of ES in capacitive as well as inductive mode is discussed. Further, the paper describes droop control method for parallel operation of distributed electric spring for stabilization the power grid. An exclusive dynamic performance of the system using electric spring has been tested and demonstrated through detailed MATLAB simulation.

Micro grid is a latest concept for upcoming energy distribution system that enables, renewable energy integration. It generally combination of multiple distributed generations (DG's), that are usually connected to the grid through power inverters. During the islanding operation (autonomous mode) of grid, important task are to share the load demand among multiple parallel connected inverters proportionately, and maintains the voltage and frequency stabilities. There are a variety of methods implements for an accurate power sharing in a single phase system when multiple DG's are connected in parallel with utility grid through power inverters. This paper reviews various control techniques for power sharing in micro grid. The control methods are divided into two parts, which are with communication and without communication. Along with, a various control techniques are compared in terms of their respective advantages and disadvantages.

Due to increasing importance of distributed generation and smart grid, solar PV systems are gaining more and more importance. However for the efficient design of the solar PV systems, solar emulator is necessary which mimics the actual PV characteristics. In this paper, a solar PV emulator with quasi sliding mode controller is presented which can simulate the real time PV characteristics under varying insolation and temperature. The advantage of the proposed emulator is that it can produce accurate I–V characteristics under fast varying environmental conditions. A low cost microcontroller based controller is developed for building the laboratory prototype of emulator. Moreover the software interfacing with user friendly GUI is developed. The proposed controller and emulator hardware can be useful for various applications like MPPT system design for automobile applications, battery chargers, inverters and grid connected systems.

This paper proposes three-level flying capacitor inverter based distribution static compensator (DSTATCOM) for shunt applications. Also, two new floating capacitors voltage balancing schemes using loss balancing technique have been proposed to balance capacitor voltages. Because of benefits like simplicity, transformation less implementation, and scope of desired power factor setting; a generalized instantaneous symmetrical component theory is incorporated to extract the reference compensator current. A basic three-level hysteresis controller is used to control the injected current by inverter so that it follows its reference value. DSTATCOM is applied to a three phase four wire (3p4w) distribution network and its effective performance is demonstrated in terms of floating capacitor voltage regulation, tracking performance and load compensation. The detailed simulation study has been carried out in MATLAB/SIMULINK to validate the suggested scheme.

This paper presents the dynamic performance analysis of grid connected Z-source inverter (ZSI) based distributed generation (DG). ZSI provides a single stage buck boost conversion which reduces the switching losses and becomes an economical option for DG systems. The standards set by the utility is met by the ZSI even during variable input conditions by regulation of shoot through duty ratio. The problems associated with dynamic changes in load can be overcome by proper design of closed loop system. The simulation and experimental results demonstrate the efficiency of the control scheme with reduced harmonics under dynamic conditions.

Requirements for smart grid are higher efficiency using power electronics and ensuring reliability of components. Refrigeration system is readily used in industries and is now becoming a commonly used household application. Now a day, voltage source inverter based BLDC drive is emerging as a more efficient controller option for refrigeration systems compared to conventional induction motors. Importance of smart grid in today's power scenario has lead to the increasing number of power electronic components for energy efficient operation. It is to be noted that, the reliability analysis of power electronic devices is very important owing to the absence of redundancy in these systems. Due to variable load on BLDC drive in refrigeration system, the component stresses and temperature cycles are necessary to be incorporated for predicting the lifetime and effective design methodologies. The major contribution of this paper is to present the method for reliability analysis of BLDC drive driven by IGBT based inverter and the overall refrigeration system. This particular method can be extended to any drive system in absence of the reliability data from the handbooks or manufacturer catalogs.

The presence of unbalanced and nonlinear loads in distribution network degrades the quality of power, which causes several problems such as load unbalancing, excessive neutral current and also increases the requirement of reactive power. This paper proposes three-level flying capacitor inverter based distribution static compensator (DSTATCOM) for shunt applications. A new floating capacitors voltage balancing schemes using loss balancing technique has been suggested to balance capacitor voltages. Because of benefits like simplicity, transformation less implementation, and scope of desired power factor setting; a generalized instantaneous symmetrical component theory is incorporated to extract the reference compensator current. A basic three-level hysteresis controller is used to control the injected current by inverter so that it follows its reference value. DSTATCOM is applied to a three phase four wire (3p4w) distribution network and its effective performance is demonstrated in terms of floating capacitor voltage regulation, tracking performance and load compensation. The detailed simulation study has been carried out in MATLAB/SIMULINK to validate the suggested scheme.

With the advent of increase in use of distributed energy systems, particularly for standalone grid connections, it is necessary that the effective control strategy has to be designed to improve the dynamic response. The Z-source inverter provides advantages over conventional inverters in the form of its buck-boost capability. Owing to its single stage power conversion, the Z-source inverter becomes an economically better option for Distributed Generation (DG) fed micro-grids/grids. The problems with dynamic changes in load can be overcome by the design of a proper closed loop system. This paper presents an effective control scheme with both AC and DC side control which varies the modulation index and shoot through time to provide the regulated voltage to the load and fed active power to the grid. The effect of changes in shoot through duty cycle with the changes in load / input variations are carried out in this work. The MATLAB based simulation results of the proposed closed loop controller are provided to demonstrate the control strategy used for step changes in input and load conditions.

Various Islanding Detection Methods (IDMs) for distributed generations are reviewed in this paper. Special consequence is put on some of the islanding detection systems based on “active methods” and “Passive Methods” for distributed generations based system. Islanding can be dangerous to utility workers, who may not realize that a circuit is still powered. Moreover, extended islanding can also prevent reconnection to power grid and may cause damage. Consequently, islanding detection, nothing but “anti-islanding”, is one of the most critical aspects of the integration of DG sources into power grid. Finally, the comparative analysis of various types of Islanding Detection Methods for multiple DG based system is overviewed on various aspects including the requirements set by interconnection standards for anti-Islanding. There are various anti-islanding detection methods and algorithms have been discussed.

For medium and high voltage applications, Multilevel inverters have been widely used as a important devices. The advantages of multilevel inverters include low electromagnetic interference (EMI) outputs, low power dissipation, low harmonic etc. The most common multilevel inverter topology is cascaded H-bridge topology constituted by IGBT semiconductors. The most common switching technology used is SPWM to obtain staircase voltage waveform. This staircase waveform contains harmonics and fundamental component. The requirement of satisfying the fundamental component is that all harmonics should be removed. The higher order harmonics can be easily removed by using filters. But lower order harmonics cannot be easily eliminated. For removing lower order harmonics non-linear transcendental equations derived from fourier series expansion should be solved. Solution to these equations can be found out by using computing methods. This paper presents a different approach, which is a advanced computing method i.e. Ant Colony Optimization method. By using ACO elimination of lower order harmonics is possible. The results shows 3rd, 5th, 7th harmonics are eliminated whereas THD is also reduced. MATLAB/Simulink software is used to validate these results.

A weigh feeder system is a small conveyor integrated with a belt weigh bridge and speed sensor and driven by a variable speed Motor. These are widely used in Mineral/Ore and chemical industry where a measured rate of solid raw material is fed to Reactors and furnaces. In order to accurately control solid flow rate, the speed of motor/ belt is varied to compensate for the variation of quantity of solid being fed on the belt. Traditionally, such electro-mechanical systems are modeled as IInd order system which ignores the non-linearity due to dead zone and frictions in the geared motor. However, as the weigh feeder is slow speed machine, the non-linearity exhibited by the machine has a bearing on fine speed control therefore the accuracy especially at low speeds. Any inaccuracy in solid feed rate affects quality and efficiency of downstream process. In order to study the effects of friction, this paper develops the model of the electro-mechanical system of an industrial weigh feeder system and studies the dynamic response of the system using MATALB SIMULINK. The results of the simulation are used to propose an innovative calculation based self-tuning discreet time PI controller to improve the control performance of the machine.

In this paper current control technique is used for reference signal generation for voltage base PWM i.e. SPWM. Voltage source inverter with the help of generalized PQ theory is implemented for shunt active filter applications. Two methods are used to generate compensated current. Current is further converted into voltage as reference signal and this is fed to the inverter's sinusoidal pulse width modulation technique (SPWM). This inverter is generating the injected current with all possible modification in the conventional single phase shunt active filter. A multipurpose single phase shunt active filter (SAPF) for domestic purpose is presented in this paper. The simulation results using MATLAB/SIMULINK are shown to validate the proposed technique. Total harmonic distortion (THD) and power factor (P.F.) are comes under the IEEE standard-519.

Now a day's distributed generations (DG) systems are generally integrated with single phase grid at small scale. The power delivered from such DG sources depends on factors like energy availability and load demand. To achieve the reliability of the system a good quality of power must be transmitted to the grid with less harmonic and unbalance. Hence proper control action is to be carried out to control the output of inverter and to transfer the power at unity power factor. This paper presents a seven level reduced switched inverter connected to the grid, which is supplied by PV array module. The MPPT is necessary to control the action of boost converter. The effective controller design for harmonic elimination and to synchronized grid frequency with inverter frequency is to be carried out using MATLAB software and simulation studies are presented.