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Lighting represents a significant component of commercial buildings, particularly office buildings. Fluorescent lighting is invariably used in all commercial, industrial and residential areas. A significant amount of lighting energy is wasted every day by leaving the lights on and not utilizing daylight energy. However, if daylight illuminance can be harnessed, this will reduce the electricity consumption of fluorescent lamps and save energy. This paper explains possible significant savings in lighting energy consumption and hence in costs, without reducing the performance and visual satisfaction in office or industrial buildings. It is proposed to obtain energy saving by reducing the supply voltage without degradation in lighting performance. Experimental results confirm that as much as 20% of electrical energy can be saved by reducing about 9% of the supply voltage, without noticeably affecting light output while complying with lighting standard limits.

An ac/dc/ac power converter is an important device used to extract power from variable speed permanent magnet wind generators and feed it into the grid. This paper describes how these converters incorporate maximum power point tracking based on its power feed to the grid at different wind speeds. Using the permanent magnet generator voltage, grid current, and grid voltage samples, the proposed system achieves an enhanced dynamic behavior. This feature effectively prevents the grid from “boost” charging the dc side of the H-bridge inverter at the start of operation. Since small wind turbines normally do not have expensive pitch control mechanisms, a thyristor-based “dump-load circuit” is employed to protect the turbine from high wind speed operation when disconnected from the grid. The thyristor controller also protects the inverter from high dc voltage input from the wind generator at high wind speed. Preliminary results are included using a laboratory 2-kW prototype converter.

The performance, including efficiency, harmonics and dead-time effect of the three major digital sinusoidal pulse width modulations (DSPWMs) presented in Part 1 are investigated in this study using a 2 kVA single-phase full-bridge inverter. Each DSPWM is implemented using a low-cost 8-bit micro-controller and the effect of different switching frequencies on the inverter performance is analysed and the inverter switching, conduction and transformer losses investigated. The experimental results confirm the validity of the mathematical and simulation analysis presented in Part 1. The work shows that the type of DSPWM used for a single-phase full-bridge inverter and the switching frequency selected can have a significant effect on the inverter performance and that switch and transformer losses make up the majority of the inverter losses.

Voltage source inverters (VSI) have been widely used in uninterruptible power supplies, unified power flow controllers or unified power quality conditioners, and distributed generation systems (DGS). VSIs are inherently efficient, compact, and economical devices used to control power flow and provide quality supply. VSIs can be classified as voltage-controlled VSIs (VCVSIs) and current-controlled VSIs (CCVSIs), depending on their control mechanism. In this paper, a detailed comparison of VCVSIs and CCVSIs for DGS applications is presented. This paper examines the advantages and limitations of each control technique in a single-phase DGS, without incorporating additional hardware and/or extra complex control techniques. Discussions on the concepts, hypotheses, and computer simulations of different VSIs in the presence of different loads and conditions are presented. The experimental results confirm the validity of the analysis and simulations outlined. The paper provides design recommendations for the use of VCVSIs and CCVSIs in various applications

In this paper, the implementation of a shunt active power filter with a small series inductor for a three-phase system is presented. The filter consists of a three-phase current-controlled voltage source inverter (CC-VSI) with a filter inductance at the ac output and a dc-bus capacitor. The series inductor is primarily used to handle the harmonic voltage source. The main concern is the size of the series inductance so that it is as small as possible but effective in compensating the harmonics. In order to select the proper value of the series inductance, the simulation is conducted to evaluate the value for different types of load.

Developing countries are faced with large shortfalls of electric-power generation, shortages of usable indigenous fuels, and transportation bottlenecks for those fuels. The loss of revenue that is forced upon the industry due to power cuts and frequent interruptions of power supply is substantial. Renewable sources of energy have an important role to play in providing much needed power in the context of growing global concern about sustainable energy supplies and protecting the environment from the adverse effects of fossil fuel utilization. The purpose of the study is to identify the factors that influence the adoption of solar-based technology. An examination of the literature in the area of diffusion of technology has led to the identification of different variables. The possible relationships that may exist between these variables is depicted in the conceptual framework. This paper attempts to clarify the relationships between the variables that have been identified and the decision to adopt.

This paper presents the complete system modelling, designing and controlling of an islanded minigrid power supply to the town of Carnarvon, Western Australia. Carnarvon power system is an isolated network supplying power to approximately 5000 people via 205km of distribution lines. The existing power system is supplied by a number of large centralized 21MW Diesel Generators. The objective of this paper is to report the design, development and installation of a Photovoltaic (PV) diesel hybrid-power system such that the operating cost can be minimized and the load on the aging generators could be significantly reduced. The proposal includes the installation of two 25kW DC variable speed diesel generators and a suitably sized advanced battery bank at each suburban transformer to ensure hundred percent penetration of solar power by residential customers in the local area. This method of control is modelled and simulated in HOMER, PSpice and Matlab. The different modes of control used to integrate maximum solar energy, reduce diesel consumption and also the methodology imposed to store excess renewable energy for operation during the night. Keywords— Hybrid system, Renewable energy, Variable speed generator, remote, Carnarvon, Ultrabattery.

Blade-tip-speed ratio feedback control is applied to a wind turbine driven, grid connected, three phase, induction generator whose wound rotor winding is connected to a rectifier via slip rings. Power from the rotor winding flows through the rectifier to a switch-mode, step-up, DC to DC converter to re-charge a bank of batteries. The switch in the DC to DC converter has a variable duty cycle, and this design feature is used in a feedback control loop. A dynamic model of the complete system is presented along with simulation results.

This paper presents the optimum operation strategy and economic analysis of a photovoltaic-diesel-battery-mains hybrid uninterruptible power supply (UPS). The system involves a photovoltaic, battery and bi-directional inverter that is connected in parallel to the grid. A diesel generator is required when the grid is not available for a longer time. The optimum operation strategy of the system is proposed for the diesel-connected mode (when the grid fails for several hours), while the economic analysis is evaluated for the grid-connected mode. The optimum strategy determines the ‘set point’ value for starting and stopping the diesel generator, resulting in a lower system operation cost within its lifetime. The optimum value is obtained by comparing the cost of the diesel fuel consumption and the battery wear. The economic analysis includes the system operation as UPS and demand side management. The system will reduce the power flow from the mains by increasing the power from the inverter to the load when the tariff is high. However, when the grid tariff is low, the power from the mains is used to charge the battery and to meet the load simultaneously.

Hybrid energy systems, integrating renewable energy technologies with diesel generators, batteries and inverters, can provide 24 h grid quality power to remote communities. Work in the Centre for Renewable Energy Systems Technology Australia (CRESTA) has been carried out to develop a new hybrid/wind/diesel/battery/mains energy system. In the system, the switching operations of different modes play an important role in the proper running of the system. From the view of discrete event dynamic systems, a novel supervisory control approach for the switching operations of modes has been explored, in which the switching actions are defined as events, switching modes as states and events take the system from one state to another. The supervisory controller for a prototype of the hybrid wind/diesel/battery/mains energy system has been designed and it has been simulated in PSCAD/EMTDC. The results reveal that this technique could facilitate the analysis and design of supervisory controllers for switching operations, particularly in the complicated hybrid energy systems.

Inverter performance is typically measured against its ability to produce a high fidelity output sinusoidal waveform with narrow band switching frequency and good transient response. For this purpose, pulse-width modulation techniques are used to generate the required control signals for the inverter semiconductor switches. Current control voltage-source inverters can be realized using one of the recently proposed zero average current error (ZACE) techniques based on analogue technology. A new and improved algorithm that belongs to the family of ZACE methods suitable for digital technology is proposed in this paper. Advantages include a more robust algorithm with quicker computation allowing fast response and higher switching frequency from a digital signal processor. The effectiveness of the new current control algorithm is demonstrated through simulations first. Experimental results taken from a low power laboratory prototype are also presented to verify the theoretical considerations.

This paper presents the design and finite-element analysis of a permanent-magnet generator using neodymium-iron-boron magnets for directly coupled wind turbines. For the sake of small size and light weight with extra low speed for direct coupling, the outer rotor structure is used. The simple magnetic equivalent circuit approach is used for initial design iteration, and the finite-element method is applied to analyze the detailed characteristics. Comprehensive experimental tests were conducted to verify the theoretical predictions. Agreement between the theoretical work and testing results was good.

This paper presents dispatch strategies for the operation of a solar photovoltaic (PV)–diesel–battery hybrid power system using ‘set points’. This includes determination of the optimum values of set points for the starting and stopping of the diesel generator to minimise the overall system costs. A computer program for a typical dispatch strategy has been developed to predict the long-term energy performance and the lifecycle cost of the system.

A model of a stand alone power supply comprising a diesel engine driven synchronous generator, a power conditioner, a bank of batteries, and an adjustable dump load is presented. The response of the power system to two different load profiles is included.

The interaction between the natural oscillatory characteristic of a nonlinear system with a periodic driving source gives rise to oscillations whose frequency depends on the amplitude of the oscillation. The existence of combination tones (both harmonic and subharmonic) in such systems, gives rise to complicated oscillatory behaviour induced by either the occurrence of the saturation of transformer cores or by system conditions leading to the reduction in the magnitude of damping. By studying the frequency characteristics (Bode plot) of single phase nonlinear power networks, the possible oscillatory modes that may be excited can be anticipated. This aspect is then extended to three phase power networks to include the influence of mutual coupling between phases and unbalance due to non-transposition of transmission lines. The Frequency Scan feature in the Alternative Transients Program (ATP) is used for that purpose.

A prototype current-controlled power conditioning system has been developed and tested on a weak rural feeder line at Kalbarri, about 600 km northwest of Perth in Western Australia. This system sources 20 kW of power from a photovoltaic array with maximum power point tracking control. In addition, it provides voltage support for the power grid at Kalbarri by varying its reactive power in response to the measured voltage at the point of connection. This paper describes the development and testing of the power conditioning system.

The occurrence of quasiperiodic (QP) oscillations in power systems, a phenomena hitherto unknown, was first experienced in the French grid when attempting to energize an unloaded transformer at the end of a long transmission line. There are no simple analytical tools available to study conditions for the occurrence of QP oscillations. In this paper, the conditions necessary for the occurrence of quasiperiodicity are shown by solving the system equations using the method of harmonic balance. It is shown that QP oscillations will occur due to the severity of magnetizing nonlinearity of the transformer core. It is also shown that if core losses are high, only frequency locked oscillations can occur. The results are confirmed by numerical solution on the original set of differential equations.

Unity and controlled power factor AC-DC power converters require a current control technique with zero average current error (ZACE) in each switching period. Acting on the current error signal alone, a ZACE controlled converter offers complete real and reactive power flow control with negligible low order current harmonics, a narrow switching frequency band, and relative immunity to DC link or AC line voltage harmonics. Slope-generated hysteresis, a new ZACE current control method is introduced. Simulation and experimental results in a three phase converter are presented. >

Nonlinear oscillations in power systems involving the excitation of nonlinear inductance with a linear capacitance in series have been termed ferroresonant oscillations, Such oscillations are unpredictable and their occurrence is of serious concern predominantly because of possible damage to equipment such as transformers. The probability of system disruption due to the occurrence of ferroresonance has increased with improvements in the characteristics of transformer steel and the use of higher and higher voltages for transmission of bulk power. Conditions that lead to the occurrence of ferroresonant oscillation, given a system, therefore, need to be known. It will be shown that for any disturbance the autonomous form of the nonlinear differential equation representing the system with two-degrees of freedom deca ys to a point attractor; that is, it is always stable. The non-autonomous form of the system's equation, however, exhibits the possibility of occurrence of a cyclic fold bifurcation which causes ferroresonant oscillations with two stable states to co-exist. Each stable state can, however, be either harmonic, periodic, subharmonic or aperiodic. Aperiodic oscillations occur when satisfactory conditions for the occurrence of subharmonic cascade exist.

A tandem induction motor comprised of two independently housed stator windings, one housing stationary and the other able to be physically rotated, and a squirrel-cage rotor common to both stators is described. When the motor is fed from a single source, altering the position of the moveable stator changes shaft speed in a similar manner to operating a normal induction motor at variable terminal voltage This paper presents an equivalent circuit model of the tandem induction motor for series-delta connected stator windings. Using the equivalent circuit stator current, power factor, and torque are calculated and then compared to laboratory test results obtained from a 3 kW tandem motor test rig

Electrical energy for remote areas has traditionally been obtained from diesel-engine driven alternators characterised by high running costs, low efficiency and high maintenance. Hybrid energy systems integrate renewable energy technologies with diesel generators, batteries, and inverters to provide highly reliable 24-h grid quality AC power to remote communities. This paper describes the application of hybrid energy systems to the electrification of remote communities in Australia. Results from a few field installations using solar and wind power are also included.

Generalized machine theory applied to a three phase twin stator squirrel-cage induction motor This paper uses generalized machine theory to develop an equivalent circuit model of a three phase induction motor comprised of two independently housed stator windings with one stator housing moveable, and a single squirrel-cage rotor whose bars extend the full length of the two stators.

A closed loop rotor resistance controller using a thyristor chopper in the rotor circuit for improving the DC dynamic braking performance of a wound rotor induction motor is presented. The control of rotor resistance is achieved by varying the duty cycle of the chopper from zero to almost unity based on the magnitude of the rotor current. During braking the feedback controller maintains a constant rotor current which results in reduced stopping time and minimum heat dissipation. The unique design of the controller allows torque control even at low speeds without the need for an auxiliary power supply for forced commutation of the controller's thyristors.

An analytical tool for studying transformer inrush current An analytical tool for studying transformer inrush current is proposed. The existing approaches dwell at length in solving differential equations which do not provide any insight into the parameters that affect inrush current. A block diagram form of representing the transformer has been proposed and verified based on typical transformer data.

This paper examines the ability of capacitors connected in the supply lines to one stator to improve the power factor and efficiency of a two stator (one moveable), single squirrel-cage, three phase induction machine termed a tandem machine. An equivalent circuit model incorporating the series capacitor is presented. Theoretical modeling for a typical set of equivalent circuit parameters and optimum capacitance show the tandem induction generator's power factor transformed from lagging to leading and the efficiency improved by one to three percentage points. Results from laboratory tests on a one horse power tandem motor for two different values of capacitance are included.

In most of the remote areas of Australia and in many other parts of the world, diesel generators are used to provide electrical power. Such systems are often characterised by either poor efficiency and high maintenance costs because of prolonged operation at low load levels, or intermittent power because the unit is only run during period of significant load. The addition of a battery bank and a power conditioner to produce a diesel-battery-inverter hybrid system has been identified as produccing a number of benefits. Such systems can be broadly classified according to their configuration as series, switched, or parallel hybrid systems. A new parallel hybrid energy system developed in Western Australia is described in this article. The heart of the system is a high quality sinewave inverter which can also be operated in reverse as a battery charger. The system can cope with loads ranging from zero (inverter only operation) to approximately three times the generator capacity (inverter and diesel operating in parallel) with excellent efficiency. The system is fully automatic, provides continuous power, and can readily incorporate input from wind or photovoltaic systems. This article also includes a description of a 5 kW wind generator charging a battery bank as part of the hybrid system, and an economic analysis indicates a favourable result for this hybrid system with payback period estimated to be the order of three years.

A predictive dispatch algorithm and control for a Photovoltaic-Variable Speed Diesel Generator battery-less hybrid energy system is proposed in this paper. The diesel generators are dispatched based on the predicted net load from the incorporated prediction models. The proposed algorithm is based on the one-hour ahead prediction models to forecast the renewable resource and the load demand. Besides, an adaptive dispatch which is based on one minute average data is also included to complement the predictive dispatch strategy. The adaptive dispatch reacts to the power flow imbalances occur during the intervals in between the prediction periods. This dual-dispatch algorithm is to ensure the on-line diesel capacity is always sufficient throughout the operation. Simulation of the system is performed using MATLAB/Simulink.

Diesel generators are widely used to supply electric power to remote and isolated areas where grid extension is prohibitive due to financial and technical constrains. In order to maintain an acceptable efficiency and moderate operation condition, the conventional constant speed diesel generators are designed to run above a specific minimum load requirement, which is normally over 50% of rated power, even though the actual load power demand is low. This results in low fuel efficiency. Operating the diesel generator running under variable speed operation can avoid the defects of conventional constant speed diesel generator. This paper proposed a simulation analysis of a stand-alone variable speed diesel generator that the rotating shaft of diesel engine is directly coupled to a doubly-fed induction generator (DFIG) to obtain an output voltage with constant frequency and constant magnitude. Indirect stator flux orientation vector control strategy is adopted to control DFIG for stand-alone operation and the simulation results are presented and confirm the validity of the strategy.

Design and optimization of a hybrid power system is site specific. It depends mainly on the available of renewable sources and the load demand. Sizing of the components has significant influence on the system performance. Due to the weather dependant nature of renewable energy sources, a fossil fuel based constant-speed generator is an essential component in traditional hybrid power systems. However, the efficiency of this generator especially at light loads can be significantly improved by adopting a variable-speed operation. This paper presents a combined sizing and operation control programme that can be used with both traditional constant-speed generators as well as novel variable-speed generators. The programme uses the polynomial curve fitting for the fuel consumption characteristics of variable-speed generators. The accuracy of the calculations is verified by comparing with a well known renewable energy optimization package.

PSPICE simulation and implementation of a thyristor d.c. chopper Simulation and laboratory results are presented of an SCR forced commutation d.c. chopper. Chopper and model operation are discussed and compared.

A controller for delivering either constant power or maximum power from a wind-turbine-driven grid connected induction generator with double stator windings, one fixed and the other able to be physically rotated, and a squirrel-cage rotor common to both stators is described. The load torque of the generator is controlled by varying the angular displacement between the two stators. The generator can feed power to the grid at variable speed and constant frequency and is termed a Tandem Induction Generator. Dynamic models for the wind energy conversion system are proposed for both controlled and uncontrolled operation to predict changes in shaft speed to shifts in wind speed using data pertaining to a commercial wind turbine. Results based on laboratory tests on a 1hp tandem machine driven by a dc motor demonstrating the feasibility of both controllers are presented. A steady state model of the tandem generator is also proposed and compared to measurements made on the test machine.

This paper examines two electric generator options for use in autonomous wind systems producing asynchronous electric power. The first makes use of a capacitor-excited squirrel-cage induction generator feeding a battery bank and an induction motor driven centrifugal pump. The second uses a permanent magnet alternator. Results obtained from field tests and laboratory experiments are included. A model to calculate the wind energy captured by a commercial 5 kW wind turbine, used in the field tests, is presented. This information is then used in a cost benefit analysis based on the present value method.

This paper presents an innovative wind/PV/diesel hybrid system implemented in three remote islands in the Republic of Maldives. The design methodology and preliminary results are presented. It is expected that the newly developed and installed system will provide very good opportunities to showcase high penetration of renewable energies using state of the art wind turbines, photovoltaic modules and advanced power electronics and control technology and the future possibilities of distributed generation in remote locations.

This paper presents a new modular hybrid power system incorporating photovoltaic and small scale wind generators connected to an AC grid formed by a doubly fed induction generator driven by a variable speed diesel generator operating in the optimum fuel efficiency mode. Preliminary experimental and simulation results of the DFIG are included. The system is proposed to replace medium scale diesel-only power stations experiencing significant variation between the peak loads and the minimum loads resulting in high fuel and maintenance costs.

This paper presents a scheme for transferring power from the photovoltaic (PV) modules to a battery using a solar charge controller based on a Cuk dc/dc converter. The converter is configured in parallel power transfer mode (PPT) to achieve higher efficiency. PWM control with maximum power point tracking algorithm is used to extract maximum power from the PV modules. Mathematical modelling and field test results using multi crystalline photovoltaic modules have been carried out to verify the effectiveness of the device.

This paper presents a finalist project proposal in the Mondialogo Engineering Award 2007 that was constructed through international cooperation between two student groups from Curtin University of Technology, Australia and Gadjah Mada University, Indonesia. The project proposes a development of sustainable power and water supply, by mean of mini-grid hybrid power system with reverse osmosis desalination plant as a deferrable load, for remote areas and disaster response and reconstruction in Indonesia. As a result of recent disasters that have hit Indonesia, many people have lost their access to a reliable power and water supply. Additionally, there are many remote areas and islands that still have no appropriate electricity supply due to geographical conditions that hinder the development of an electricity grid connection because of economic reasons. This paper describes concept of system design process, intercultural dialogue between two student groups from different countries, preliminary site visits on the disaster locations in Yogyakarta, Indonesia, and previous experimental results on 5 kVA mini-grid hybrid power conditioner system, a reverse osmosis desalination plant rated at 5.5 kWh/day, and the upgrading of PV arrays for solar water pumping system (SPWS) rated at 375 W, all are performed at Curtin University of Technology. Through this project, students from Australia and Indonesia collaborated to participate in attaining The United Nations' Millennium Development Goals, especially on eradicating extreme poverty and hunger, ensuring environmental sustainability, and developing a global partnership for development.

This paper will show the theory, simulation and application of maximum power point tracking for small scale wind turbines. The theoretical section of this paper will cover modelling of the wind turbine, the and the power electronic converters (the full-bridge DC/DC converter and the grid connected current controlled voltage source inverter (CCVSI)). It is shown that by controlling the duty ratio of the DC/DC converter, the wind turbine generator is operated at the maximum power point. This is achieved without measuring the wind speed using a look up table where the power output vs the shaft speed is recorded. In order to keep the output current waveform sinusoidal at varying wind speeds, the DC link voltage of the CCVSI is kept constant. This system meets the utility requirements such as galvanic isolation, anti-islanding protection and protection of the wind turbine at high wind speeds.

In this paper, the implementation of a three-phase shunt active power filter is presented. The filter is essentially three independent single-phase current-controlled voltage source inverters (CC-VSI) with a common DC bus. The CC- VSI is operated to directly control the AC grid current to be sinusoidal and in phase with the grid voltage. The APF consists of a current control loop, which uses polarized ramptime current control and a voltage control loop, which employs a simple Proportional Integral control. The experimental results indicate that the active filter is able to handle predominantly the harmonics, as well as the unbalance and reactive power, so that the grid currents are sinusoidal, in phase with the grid voltages and symmetrical.

This paper describes the development of an illumination system for open and/or isolated areas like gardens, sidewalks, outdoor lighting for residences and rural areas, demonstration plants on Universities, et cetera. The proposed system is based on a 70 W electronic ballast (EB) for high- pressure sodium (HPS) lamps designed to operate from a low voltage automotive lead-acid battery charged by a hybrid wind- solar power system. A new design criteria for a push-pull EB based on the rated current RMS of the lamp is presented. The paper also includes technical issues faced in building the prototype such as transformer losses generated by skin effect, transformer winding isolation and the effect of high MOSFET drain source current.

This paper presents a comparative analysis of the parallel operation of different switches in a switch mode power converter. In high power applications, multi-switch PWM power conditioners may be preferred despite a higher component count, due to the absence of low frequency filters, reduced switching losses and fault tolerance. The paper demonstrates how current sharing (CSH) and time sharing (TSH) lead to the reduction of switching stress in the parallel operation of switches in any converter. The solutions proposed in this study can be applied on different scales to other power conditioners for renewable energy applications. Discussions of the concepts, hypotheses and computer simulations are verified by 1 kW experimental results

This paper presents a grid-connected photovoltaic (PV) system with direct coupled power quality controller (PQC), which uses an inner current control loop (polarized ramp time (PRT)) and outer feedback control loops to improve grid power quality and maximum power point tracking (MPPT) of PV arrays. To reduce the complexity, cost and number of power conversions, which results in higher efficiency, a single stage CCVSI is used. The system operation has been divided into two modes (sunny and night). In night mode, the current controlled inverter (CCVSI) operates to compensate the reactive power demanded by nonlinear or variation in loads. In sunny mode, the proposed system performs PQC to reduce harmonic current and improve power factor as well as MPPT to supply active power from the PV arrays simultaneously. It is shown that the proposed system improves the system utilization factor (SUF) to 100%, which is generally low for PV systems (20%). Mathematical modelling, computer simulations and experimental results for a 1 kVA CCVSI are presented

This paper describes a novel low-cost grid-connected inverter for small-scale wind turbines based on a high-inductance PM generator operating in a constant-current output mode. The PM generator is connected to a switchedmode mode rectifier (SMR) which consists of an uncontrolled rectifier and a switch. The combination of the high-inductance generator and uncontrolled rectifier produces a constant dc current. The switch is used to modulate this current and produces an output current whose fundamental component is a full-wave rectified sinewave and is in-phase with the grid voltage. A line-frequency commutated H-bridge inverter and LC output filter is used to produce a sinusoidal output grid current. The concept is verified using simulations and experimental results.

This paper presents a study on the effect of different parameters on the DC bus of a single-phase voltage controlled voltage source inverter with conventional rms voltage feedback control and a wave-shaping controller. As rms voltage feedback control does not compensate for variations in the DC bus voltage due to its inherently slow response, the addition of DC bus feedback compensation can provide performance improvement. The paper demonstrates how a DC bus compensation controller improves the performance of a wave-shaping controller, which maintains a sinusoidal load voltage for all loading conditions. Mathematical modelling, computer simulations and experimental results based on a 2 kVA inverter are presented

This paper analyses a wave-shaping controller (WSC) in detail and examines the effect of different parameters, their advantages and limitations on the stability of a single-phase voltage controlled voltage source inverter (VCVSI) without incorporating additional hardware and/or extra complex control techniques. It is shown that the proposed improved WSC can maintain power quality in the presence of non-linear loads and abnormalities. Discussions of the concepts, mathematical modelling, computer simulations and experimental results for a 2 kVA inverter are presented

This paper presents the implementation of two digital sinusoidal PWMs (DSPWMs) using a low-cost 8-bit micro-controller. Each DSPWM is implemented using two different PWM hardware modes on the micro-controller. The benefits and limitations of each DSPWM are investigated in relation to the switching frequency and micro-controller performance from experimental verification using a 2 kVA single-phase inverter. The standard left aligned PWM module found on low-cost micro-controllers is shown to provide performance benefits similar to a DSPWM requiring a higher-cost micro-controller for its implementation. The main benefit being the reduction in microcontroller resources, allowing more time for features such as protection, monitoring, interfacing, variable switching frequency and grid synchronization

In this paper, a control and design consideration of PV/ diesel hybrid distributed generation system using dual inverter for weak grid is presented. The dual inverter employs a combination of a voltage controlled voltage source inverter (VCVSI) and a current controlled voltage source inverter (CCVSI), connected in series on the DC side and in parallel on the AC side. This system is able provide an uninterruptible power supply (UPS), load voltage stabilization, unity power factor correction, maximum power point tracking (MPPT), and demand side management (DSM). To verify the proposed system, a comprehensive evaluation with theoretical analysis and experimental results is presented.

This paper describes a novel space vector modulation method for single-phase inverters suitable for an uninterruptible power supply (UPS) and other applications. This modulation method combines the flexibility of the wellknown unipolar PWM for single-phase inverters with the maximum harmonic mitigation. Six switching methods are presented, evaluated and classified for different single-phase applications, including deadband effects. Simulations using Matlab/Simulink confirm the validity of the proposed PWM. Mathematical analysis and comparison of SPWM with the proposed space vector modulation for single-phase inverter are presented.