Search

The Dynamic Economic Dispatch (DED) problem consists in satisfying a certain demand for electric power among scheduled generating units over a certain interval of time while satisfying the operating constraints of these units. The consideration of the valve-point effect (VPE) makes the problem more practical but also more challenging due to the non-linear and non-smooth constraints that are required for representing the model. We present a method, based on a sequence of piecewise linear approximations, which produces a feasible solution along with a lower bound on the global solution. In this way, this deterministic approach can trade off the speed which characterizes certain heuristics that are usually used to solve the DED-VPE for a better solution and insights about the problem. The method is applied to a widely used case study and provides a lower solution objective than the best known solution to date.

We present a stochastic unit commitment model for assessing the reverse requirements resulting from the large-scale integration of renewable energy sources and deferrable demand in power systems. We present three alternative demand response paradigms for assessing the benefits of demand flexibility in absorbing the uncertainty and variability associated with renewable supply: centralized co-optimization of generation and demand by the system operator, demand bids and coupling renewable resources with deferrable loads. We present simulation results for a model of the Western Interconnection.

SNCF is the largest electricity consumer in France. The rolling stock has the highest share of France railway system electricity consumption at 84%. The traction power of High-Speed Trains (HST) can reach up to 50% of the total rolling stock electricity consumption during the rush hours of weekdays. Given the new policies regarding energy regulation in peak power demand periods, load modulation by the traction power of HST is one of the flexibilities that are investigated by SNCF in the Smart Grid project. This paper presents the study related to the feasibility of a Targeted Traction Power Modulation (TTPM) of HST. Experimental tests have been achieved as proof of concept on the SNCF South-Europe-Atlantic HS line. Experimentation results showed between 20 and 30% of energy savings during the peak power demand period. Refereed/Peer-reviewed

This paper optimally determines the configuration of the system, as well as each component capacity, in order to design a cost-effective and environment-friendly AC mini-grid hybrid power system for a remote area in South Australia. To this purpose, a modified Multi-Objective Particle Swarm Optimization (MOPSO) algorithm is applied. In each iteration of the modified proposed MOPSO, first, renewable power sources, including photovoltaic arrays and wind turbines along with energy storage components, are selected to form a hybrid power system along with the diesel generator. Then, the capacities of the components are optimized based on two objective functions, including Levelized Cost of Energy (LCOE) and CO2 emission, by analyzing the system using real data in hourly time-step for the load, solar insolation, ambient temperature, and wind speed over a 20-year timespan. Afterward, positions for system configuration and component capacities are updated according to the objective functions. Refereed/Peer-reviewed

Robustness, low cost and high torque density are the main characteristics of switched reluctance machines (SRM) that have made them promising for a variety of applications. In this paper a small diameter, long stack length (small aspect ratio) 6kW SRM is designed. In the first step, the dimensions of the studied SRM are derived based on conventional sizing equations. The significance of the rotor and stator pole arcs and also the effective torque zone as a constraint of the design are discussed. A finite-element study is carried out to validate the analytical model of the proposed SRM. The performance of the machine is comprehensively studied in different operating speeds. Simulation results demonstrate the capability of the machine for operation over a wide speed range.pa Refereed/Peer-reviewed

Load flow problems in electricity distribution systems (EDS) are generally solved through iterative methods such as Newton-Raphson, Gauss-Seidel, Forward-backward Sweep-based methods, etc. These methods are subject to problems such as poor convergence for EDSs with high R/X ratio branches and huge mathematical/programing burden in some cases. Moreover, in EDS studies such as power loss minimization, energy management, EDS planning/expansion, etc., load flow calculations need to be conducted alongside the required objective function and the related constraints of the study. To solve such models, optimization techniques such as metaheuristic methods, are used in which load flow calculation is conducted in each iteration, bringing extra mathematical burden. To address these limitations, this paper presents a new directly solvable and non-iterative load flow model which is developed using a new bus indexing procedure. A connectivity matrix is introduced to characterize the configuration of EDS and provide a feasible general representation of load flow equations. This enables the proposed modified load flow equations to be mergeable in any type of EDS study as model constraints. Moreover, unlike previous iterative models, it can be solved directly through standard optimization packages in a single shot with no need to further iterative optimization procedures, such as metaheuristic methods. This results in a moderate mathematical and programing burden. The 33-bus system is employed to evaluate the effectiveness of the proposed load flow model. The obtained results are reported and compared with forward-backward sweep-based load flow as a benchmark. Accordingly, it is shown that the proposed model maintains the same outcome without using iterative optimization techniques. Refereed/Peer-reviewed

With the predicted proliferation of Electric Vehicles (EV) worldwide over the next decades, effective EV charging strategies and the associated costs are of utmost interest. In addition to EV charging at home, various countries are introducing public charging facilities for fast charging of EVs. While there are implications of the various charging strategies on the load demand profile of the grid, the cost of charging EVs as well as the overall energy cost for households remain important drivers for the uptake of EVs in countries around the world. This paper investigates these critical aspects in the South Australian context, by examining various EV charging strategies and tariffs. The paper also investigates the impact of the charging strategies on the South Australian load demand profile. Refereed/Peer-reviewed

This paper presents the design and analysis of a novel axial-flux synchronous reluctance motor (AFSynRM). A magnetic equivalent circuit (MEC) model for the proposed axial-flux machine is derived. The feasibility of fabrication is discussed. Finite-element analysis is applied to predict the performance of the proposed motor design. This paper provides a baseline study by comparing the performance of the proposed AFSynRM design with a similar rating radial-flux motor. The motors are designed to have similar volume and both have three rotor barriers. The operating parameters are obtained through static and dynamic FEA. The power, torque, power factor and efficiency of the motors are studied. The saturation and flux distribution in the motor structures are investigated. Refereed/Peer-reviewed

This paper investigates a comparative study on optimal sizing of fuel cell (FC) and battery energy storage (BES) systems coupled with solar photovoltaic (PV) and wind turbine (WT) for a remote area power system. Two system configurations: (1) PV-WT-BES and (2) PV-WT-FC are optimally sized based on actual annual data of wind, solar radiation, ambient temperature and load profile of a remote area community in South Australia. The costs of generation and storage units are considered based on real Australian market prices. The levelized cost of electricity (LCOE) is used as the objective function and appropriate optimization constraints are considered for each system. It is found that the BES technology is more economic than FC system for power system design in Australian remote areas. However, the PV-WT-FC system results in lower dumped energy. Sensitivity analysis is conducted to investigate the effects of the FC system price and its efficiency on LCOE and dumped energy of the system. The option of adding reactor/reformer to the FC system to produce hydrogen from the human waste is also studied in terms of optimal capacities, economic and dumped energy. Refereed/Peer-reviewed

This paper proposes a dual rotor halbach array permanent magnet vernier machine (DRHAVM). Proposed vernier machine demonstrate high power factor with high torque density at low speed which is promising for low speed transportation applications. Proposed permanent magnet vernier machine structure omits necessity of gearbox and directly convert energy to low speed rotation. A comprehensive FEA of proposed DRHAVM including sensitivity analysis, back-EMF, torque density, torque per magnet volume, power factor, core loss, copper loss and efficiency are performed. Additionally, a detailed comparison is conducted between proposed DRHAVM and other types of Vernier machines in the literature. Results display that proposed halbach array vernier machine structure can achieve an appropriate power factor (0.84) and generate higher torque (2850 Nm) at speed rotation of 30 rpm. Refereed/Peer-reviewed

To eliminate the negative-sequence and harmonic currents in the traction system of electric trains, a novel compensatory algorithm is proposed for half-bridge-converter-based railway static power conditioner (HBRPC) by applying impedance-matching (IM) transformers. HBRPC is composed of two half-bridge converters along with two capacitors which makes use of a smaller number of power switches in comparison with conventional compensators. It consequently becomes cheaper than the conventional compensators. This article proposes an algorithm to generate reference current composing of active, reactive, and harmonic current which compensates negative-sequence and harmonic currents on the three-phase side. The simulation results show that the proposed algorithm compensates negative-sequence and harmonic currents in the same range as other compensators, respecting lower expenses.

This paper presents a novel dual-stator linear-vernier permanent-magnet (DSLVPM) machine. The proposed machine utilizes consequent-pole permanent magnets (PMs) rather than the adjacent topology of conventional linear-vernier permanent-magnet (LVPM) machines. The proposed structure of DSLPMV is analyzed and compared against the conventional topology of the LVPM machine. 2D finite-element analysis is utilized to evaluate the electromagnetic aspects and performance parameters of the machines at no-load and full-load conditions. To assess the machines with different PM volume usage, indices such as thrust force per magnet volume (FPMV) and back-EMF per magnet volume are introduced. Simulation results display a better performance of the proposed linear vernier machine in comparison with the typical machine due to the optimized usage of magnets in the consequent-pole configuration.

The proliferation of rooftop solar PV has caused reverse power flow in low voltage distribution networks leading to elevated voltage levels. As the voltage is raised, PV inverters reduce output power to combat voltage rise and may result in inverter shutdowns causing PV curtailment (loss of PV output power). Residential battery storage can store excess PV energy and hence reduce reverse power flow, over voltage and PV curtailment. This study aims to determine the reduction in PV curtailment achieved by the installation of optimally sized residential battery storage. A method to calculate the reduction in PV curtailment and the reduction in corresponding financial losses incurred by PV owners and the energy market is presented. The method is applied to an 11-kV feeder in South Australia along with prevailing feeder and inverter voltage limits. Results show that with the installation of optimally sized battery storage, PV curtailment and the corresponding financial losses can be reduced by more than 50%. Refereed/Peer-reviewed

Flexible ac transmission systems (FACTS) devices are commonly used in power systems to improve the dynamic and static performances of the system. Battery energy storage systems (BESS) are now increasingly being installed in modern power systems for energy arbitrage and ancillary services. This paper describes a technique to improve the transient stability limit of a simple power system using a BESS. A previously developed control strategy to improve stability using STATCOM is applied to control the BESS. The strategy is based on a combination of the maximum and continuous current control. The stability limit, and hence the critical clearing time, obtained using BESS is compared with that obtained using STATCOM. A classical model of the system has been implemented in Matlab Simulink and DIgSILENT PowerFactory software for the analysis. Further analysis has been conducted for a higher order machine model implemented in PowerFactory. The investigations revealed that the BESS is more effective in enhancing the stability limit of the system compared to a STATCOM of the same current rating for both classical and higher order machine models. Refereed/Peer-reviewed

This paper proposes a piecewise-affine decision rule based stochastic optimal power flow approach for reserve dispatch of generators under uncertain demand and renewable energy source generation. The ambiguity set comprises a predefined set of scenarios to capture the plausible uncertain realizations. The objective is to minimize the expected generation cost under those scenarios. A piecewise-affine decision rule is established with auxiliary control parameters to compute the optimal participation of generators depending on the amounts of reserve requirements. Such a reserve dispatch rule would be less conservative compared to the traditional affine decision rule. The results illustrate that the proposed piecewise-affine generation redispatch rule improves the optimality of operation via efficient resource utilization for reserve support. Ministry of Education (MOE) Accepted version Mohasha Isuru and Eddy Y. S. Foo acknowledge the support of the Singapore Ministry of Education Academic Research Fund Tier 1 Grant (MOE2018-T1-002-093).

This paper presents design optimization of axialflux induction motors (AFIMs) for electric vehicles. The approach is based on an analytical resolution of the Maxwell's equations inside a set of subdomains. The analytical method is verified against 2D finite-element analysis. It allows detailed modelling and accurate steady-state performance prediction of AFIMs in a very short time (under 1sec), making possible evaluation of numerous design for the optimization. The optimization effortlessly simulates and predict the performance of various AFIM designs based on driving cycles and vehicle limitations. An optimization based on driving cycle of electric vehicles is studied through considering a driving cycle and designing minimum-mass AFIMs capable of fulfilling it. It is observed that driving-cycle based motor designs benefit from mass reduction and ensures the feasibility of all operating conditions Refereed/Peer-reviewed

Measuring the efficiency map of an electric machine is a complex and time-consuming process. This paper examines means for estimating the efficiency map of PM machines using a reduced number of tests. It uses a modified saturation model which gives good results even in the presence of high cross-saturation. It also models the iron loss variation with load and speed using curve fitting in the constant torque and power regions based on a limited number of load points. Both the flux-linkage and iron loss methods are applicable to finite element (FE) simulation and have the capability of being generalized to other electrical machine types. The results are verified both with FE simulation and experimental tests. Refereed/Peer-reviewed

Step-up DC-DC converters play a determinative role in traction vehicles by providing the required DC- link voltage for traction drives supplied by battery packages or fuel cells. Bi-directional converters are preferred to be used in the construction of battery-based traction drives to charge batteries when drivetrains system work in the generation mode. However, due to the fact that fuel-cells cannot be charged electrically, the bi-directional structure is not required for fuel cell-based traction drives. The proposed step up converter benefits from the resonance between its elements to provide the soft- switching condition for the converter switches. The resonance assists to transmit high power from input and to output while there is no high-frequency transformer or coupled inductor in the converter topology. In brief, the generated resonance not only leads to a high power density converter but also result in a soft-switching which means higher efficiency in comparison to previously introduced high-step up converters working in hard switching condition. So, the proposed high-efficiency high power density high step-up (HHH) converter could be employed as a reliable DC-DC converter for traction vehicles supplied by fuel cells. Refereed/Peer-reviewed

Self-sustainable autonomous microgrids with 100% converter-connected generation are most suitable for powering remote areas without impacting the environment. This work focuses on the regulation aspect of such islanded microgrids by sizing and controlling energy storage systems to support the renewable energy-based microgrids. Each generation unit in the microgrid acts as a voltage-source that contributes to frequency and voltage regulation, wherein the regulation is achieved by a modified droop control that emulates the inertia property of synchronous machines. The size of energy storage systems that support this task is estimated based on the allowable regulation standard and control scheme. The designed storage and control are validated with the help of real-time simulation. Accepted version

This paper presents a Zero-Voltage-Detector (ZVD) circuit for buck converters working in discontinuous conduction mode (DCM). A novel comparator with pre-amplification property is proposed to provide fast sensing and comparison to optimize the switching timing of power transistors, hence minimizing the power losses caused by the reverse inductor current. The proposed DCM buck converter is fabricated using 0.18um CMOS technology with a chip area of 0.9mm 2 . The simulated sensing delay of the proposed ZVD is only about 6ns. It achieves > 85% power efficiency for load currents of > 10mA when the input and output voltages are 3.3V and 2.4V respectively. Agency for Science, Technology and Research (A*STAR) Economic Development Board (EDB) Nanyang Technological University The author would like to acknowledge MediaTek and EDB for JIP scholarship, and funding support from NTU-A*STAR Silicon Technologies Centre of Excellence under the program grant No. 11235100003.

In this paper, an active shaping method of the capacitor voltage for a cascaded H-bridge (CHB) Iow-capacitance static synchronous compensator (LC-StatCom) is introduced. The traditional LC-StatCom is able to operate with large capacitor voltage ripples when it is operating with rated current. However, as the current is reduced below rated current, voltage ripple on the capacitors decreases. Decreasing the current therefore removes the advantages of the LC-StatCom such as better current quality and reduced switching losses. The active shaping method aims to keep consistent large voltage ripple on the capacitor using a simple boost converter cell to inject an appropriate auxiliary capacitor current. Simulation results are provided to confirm the performance of the proposed CHB-StatCom system. Accepted version

The use of film capacitors to substitute traditionally utilized electrolytic capacitors is a well-known trend in the power electronics industry as it significantly increases the overall reliability of the system. Control challenges arise due to the reduced capacitance of film capacitors with similar volume and weight as electrolytic capacitors. To address these control challenges, previous works have shown the good accuracy and fast dynamic performance of analytical filters to remove low-frequency capacitor voltage ripples. However, as these filters are based on an idealized mathematical model of the system, some harmonic content remains in the filtered signal due to discrepancies between the real system and utilized model, which deteriorates the overall performance of the system. In this paper, an improved adaptive filtering scheme for a low-capacitance static compensator (LC-StatCom) is proposed. The scheme mitigates both time delays and harmonic-contamination in the outer capacitor voltage control loop. Hence, the proposed solution allows the use of a high bandwidth controller and the generation of a current reference free of low-frequency harmonics. The effectiveness of the proposed approach is validated via simulation results on a seven-level 0.35-kVA single-phase LC-StatCom. The results demonstrate that the proposed solution overcomes drawbacks of previous schemes in terms of time response and filtering performance in steady-state operation. Accepted version

This paper proposes two suitable converter topologies for more electric aircraft (MEA) starter generator application. The commercially available silicon (Si) and silicon carbide (SiC) semiconductor devices are also sourced to fit the given design requirements. Different possible configurations of the evaluated converter topologies are discussed. The rectifier design methodology is presented, considering device loss distribution, converter efficiency, required heatsink thermal resistance, dc-link capacitance sizing, delivered power quality and estimated gravimetric power density. The quantitative evaluations have demonstrated the beneficial needs of driving multilevel converter at higher switching frequency operation using SiC semiconductor technology. National Research Foundation (NRF) Accepted version This work was conducted within the Rolls-Royce@NTU Corporate Lab with support from the National Research Foundation (NRF) Singapore under the Corp Lab@University Scheme.

In this paper, a new modulation technique is presented which aims to enhance the natural voltage balancing capability of neutral-point-clamped converters. The traditional carrier-based pulsewidth modulation technique with zerosequence injection faces some drawbacks, namely, its inability to balance initial capacitor voltage imbalances quickly and the divergence of the capacitor voltages in the presence of nonlinear loads with even harmonics. This paper aims to find a trade-off between voltage balance performance and switching losses by reducing the difference between the average capacitor voltages without incorporating any external circuitry. A reference neutralpoint (NP) current is generated using the average difference between the capacitor voltages. Depending on the reference NP current and predicted NP current, appropriate duty cycles are applied to switch the three phases. These duty cycles are directly linked to the voltage unbalance between the capacitor voltages and thus provides the necessary ‘push’ to mitigate deviations in natural balancing characteristics. To validate the proposed modulation technique, simulation results are presented for linear loads as well as for nonlinear loads with even harmonics. Accepted version

The concept of community microgrid distribution system presents a new framework for operation and management of the future distribution systems with various operating constraints and a business model. It aims at extending the benefits of traditional microgrid by sharing the energy resources among multiple partners. Peer-to-peer (P2P) energy trading model seems to be one of the suitable models for energy trading in the future community microgrid distribution system. This paper proposes a hierarchical peer-to-peer (HP2P) energy trading framework for future community microgrid distribution networks to provide efficient energy trading in the microgrid energy market. The proposed HP2P framework is applied to a sample community microgrid distribution system. It results in cost saving and hence its effectiveness is verified by simulation study. Accepted version

The maximum power point tracking (MPPT) is generally implemented in grid-connected photovoltaic (PV) power plants to maximize the energy yield. However, as the penetration level increases, challenging issues such as overloading and overvoltage arise in PV applications. Accordingly, a constant power generation (CPG) operation, in which the PV output power is limited to a specific value, has been imposed by some grid regulators to alleviate the integration challenges. In that case, the combined operation of MPPT and CPG is required, which increases the complexity of the controller design. To generalize the two control objectives, a flexible active power control algorithm that combines both MPPT and CPG operating modes is proposed. The proposed algorithm can optimize the performance in both modes (i.e., MPPT and CPG). By adjusting the voltage-step between two consecutive operating points, fast dynamics and low-power oscillations can be obtained. The performance of the proposed strategy is evaluated through simulations and experiments under different irradiance and power reference profiles. Accepted version

International audience; This paper presents the initial findings on a new forecast approach for ancillary services delivered by aggregated renewable power plants. The increasing penetration of distributed variable generators challenges grid reliability. Wind and photovoltaic power plants are technically able to provide ancillary services, but their stochastic behavior currently impedes their integration into reserve mechanisms. A methodology is developed to forecast the flexibility that a wind-photovoltaic aggregate can provide. A bivariate Kernel Density Estimator forecasts the probability to provide reserve. The methodology is tested on a case study where volumes of automatic Frequency Restoration Reserve (aFRR) are forecasted on a day-ahead horizon. It is found that the wind-photovoltaic aggregate can dedicate a limited share of its forecast production to aFRR. The frequency of insufficient reserve capacity is assessed, by comparing the capacities offered with the measured production.

In demand side management electricity consumers are systematically encouraged by a load serving entity (LSE) to adjust their electricity demand to reduce overall costs. Li et al. [1] have presented such an iterative demand response program. In each iteration it sends price signals to the consumers against their demands for each hour of the day ahead, and smart consumer appliances adjust their usage accordingly to maximize their utility given the prices. The price signal is the marginal cost based on a single quadratic and piecewise smooth cost function. We extend previous work to allow multiple cost functions one for each supplier, and require that the LSE optimizes procurement jointly with the demand response. The price signal is then based on the optimal cost of procurement from all suppliers, computed using sequential quadratic programming (SQP). However, when the number of cost functions grows computing the price signal in each iteration becomes a bottleneck. Therefore, we also introduce an approximation technique based on knowledge compilation, in which the procurement problem is first represented in discrete form in propositional logic, and compiled into a tractable form known as decomposable negation normal form (DNNF). The DNNF is then used for efficient computation of near optimal prices in each iteration. Refereed/Peer-reviewed

This paper presents a CMOS rectifier operating at 2.45 GHz for RF energy harvesting. The diode forward voltage drop, forward peak current and reverse leakage current issues have been addressed by utilizing a novel DC-boosted biasing technique. The proposed rectifier is implemented in 65 nm 6M/1P standard CMOS technology. In simulation, the proposed rectifier achieved peak efficiency of 59.6% with input power of -12 dBm at 2.45 GHz and 29 kΩ output load. PCE greater than 20% can be achieved over an extended input power range of 19 dB from -18 dBm to 1 dBm. The proposed rectifier has sensitivity of -17 dBm for 1 V output voltage. Economic Development Board (EDB) The authors would like to thank VIRTUS, EDB Singapore and GLOBALFOUNDRIES Singapore Pte Ltd for supporting this work.

Modelling and simulation of emerging DC shipboard power system (SPS) is required to validate the hardware design, converter control and protection algorithms. As DC SPSs may be large and complicated, the simulation of such systems using high fidelity models generally consumes much time and the validation of performance using multiple test scenarios becomes impractical. An alternative method is to conduct such simulations in real-time using a multi-core simulation platform. Real-time simulation also allows protection relays (running embedded protection algorithms) to be verified through `hardware in the loop' techniques. In this paper we discuss the simulation of DC SPSs in real-time using Opal-RT simulation platform. Firstly the system is modelled for non-real-time simulation. Subsequently these models are converted for real-time simulation and executed using RT-Lab on the Opal-RT target. Modelling and control approaches of DC SPS and some of the attributes of Opal-RT are also discussed. NRF (Natl Research Foundation, S’pore) Accepted version

Solid State Power Controller (SSPC) is gaining popularity, replacing mechanical switches and circuit breakers, in niche markets like electrical power distribution systems of the more electric aircraft. Significant amount of research is being conducted to develop high power SSPCs to cater the dynamic, distributed load management. The 28V SSPCs are widely used for protection and control of the secondary distribution system. Although there are high current SSPCs for low bus voltages, the 270V SSPCs are not mature and high current 270V SSPCs are not available in the market or having limited capability, which would be used in the primary power distribution system of the aircraft. This paper presents the market availability, design challenges the design engineer should be aware of and various approaches adopted to design and develop a high current 270V DC SSPC for more electric aircraft system, its key features which may not have been available in the traditional switches and future trends. National Research Foundation (NRF) Accepted version This work is jointly funded by National Research Foundation (NRF) Singapore, Rolls-Royce Singapore Pte. Ltd, and Nanyang Technological University, Singapore.

This paper presents new gating techniques to improve the efficiency of zero-voltage zero-current switching (ZVZCS) full-bridge DC-DC converter for battery charging in electric vehicles. The converter is assisted by a passive auxiliary circuit to extend the zero voltage switching range. The uncontrolled auxiliary circuit current increases the conduction losses of the converter when gated with conventional phase-shift modulation (PSM) technique. The controlled auxiliary circuit current with the proposed pulse-width modulation (PWM) gating techniques increases the efficiency of the converter especially at light-load conditions compared to PSM. In this paper, the steady-state analysis of the converter auxiliary circuit with the PWM gating techniques is presented. A comparative loss analysis with PWM and PSM gating techniques is also given. A 1.2-kW, 100-kHz converter is implemented on ORCAD-Pspice and the simulation results are presented to validate the improvement in efficiency of the converter with the proposed PWM gating techniques. Accepted version

Often, remote locations are not within close proximity to a mains power grid. A common solution to providing electricity in remote areas is diesel generation. Historically, it is a type of power generation that is proven reliable, but not without adverse environmental impacts. Diesel generation is not capital intensive. However, it can have long term negative financial impacts as well as producing less than desirable amounts of greenhouse gases due to excessive consumptions of diesel fuel. Alternative is the use of renewable sources especially that e.g. solar energy is vastly available in the Australian outback. However, solar generation, unlike diesel requires large initial capital investment, which companies are hesitant to allocate without a proper economic analysis of alternative solutions. To alleviate these concerns, this article investigates the economy of the use of renewable sources complemented by diesel generation for a remote area pump station. It is shown that diesel powered system not only has inevitable adverse environmental impact but also contributes to the company's financial inefficiency. Refereed/Peer-reviewed

An Integral Fast Output Sampling (IFOS) control for controlling the tip position of single link Flexible manipulator which is a multivariable system has been presented. Fast output sampling scheme eliminates the need of an observer required for the estimation of internal states of the system. The gain of the IFOS controller is obtained by solving system of Linear Matrix Inequalities (LMI's) using CVX optimization toolbox. Modelling of Flexible Link Manipulator (FLM) system has been presented. IFOS control scheme is compared with an observer based discrete time state feedback strategy.

Fault ride through (FRT) capability is one of the challenges faced in the medium to high voltage grid-tied large-scale photovoltaic (PV) power plants. This paper proposes a novel control strategy to enhance the FRT capability of a two-stage multi-string PV plant which consists of DC/DC converters and NPC inverter. The proposed control is implemented to the DC/DC converter to maintain the DC-link voltage under any grid fault conditions by adjusting the extracted PV power to the inverter output power. This is achieved by changing the PV string reference voltage from its maximum power point voltage to a new voltage point with less power. On top of that, a novel voltage-oriented control (VOC) control structure using proportional-resonant (PR) controller is proposed for the NPC inverter. Additionally, the DC-link capacitor voltages are remained balanced at all times due to the adaptive space vector modulation (ASVM) scheme. The evaluation results have verified the feasibility and the FRT capability of a 14kW PV plant using the proposed control scheme under different grid fault conditions. ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version

A five-level reduced device multilevel inverter is proposed for driving permanent magnet synchronous motor. The proposed multilevel inverter drive consists of lesser number of clamping diodes compared to the conventional five-level diode clamped inverter. An active balancing circuit is used to provide balanced voltages across the four dc-link capacitors to ensure five-level voltage waveform in all operating conditions. The field oriented control of a permanent magnet synchronous motor using space vector modulation technique is implemented to investigate the performance of the proposed inverter drive and results are presented based on simulation done in Matlab/Simulink® and PSIM environment. ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version

by Chandrasekaran Subramanian and Ragavan Kanagaraj

While penetration of Distributed Generators (DGs) has been increasing with favorable government policies coupled with technological advances in portable deployment of DGs, the challenges of efficient network operations in secondary distribution networks have also become formidable. Among other issues, the real power penetration from PV and Wind generators causes imbalance between real and reactive power flows in low voltage distribution networks where phase unbalancing and variation in demand-supply have dominant effect on voltage profile, overloads, power factor and losses. This paper attempts to apply sequential time simulations approach by performing distribution power flow simulations for time-series data points of demand and generation over a period of one year at 15 minute intervals. This approach helps in capturing the diurnal and seasonal variability of intermittent power producing DGs and that of load profiles. It also helps in undertaking time integral studies for energy losses, number of switching operations by control devices such as shunt compensators and voltage regulators. The results of this exercise are used to propose different switching strategies to limit voltage limit violations while reducing annual energy losses.