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Optimization of wireless power transfer (WPT) systems with high performance and misalignment tolerance is investigated in this paper. Key performance indices of WPT are power transfer efficiency (PTE), transferred power (TP), and misalignment tolerance. Misalignment can be radial, axial, or angular, depending on the WPT receiver's degrees of freedom (DoF). A figure of merit (FOM) is proposed to optimize PTE, TP, and six-DoF (6DoF) misalignment tolerances simultaneously. Misalignments in 6DoF are segmented into subregions, and performance within each region is prioritized based on probability of alignment in deriving the FOM. A WPT system with tri-spiral repeater is introduced with the use of proposed FOM as the optimization objective. Theoretical analysis is experimentally validated.

This paper presents a high step-up scalable voltage multiple cell (SVMC)-based DC/DC converter, which has the features of high gain, low and adjustable components stresses and automatic input-current sharing in each input-phase. In virtue of above features, the converter is applicable for the DC collection grids for offshore wind farms. In this paper, the converter in terms of working principle and property characteristics are analysed with 4 input-phases and 3 SVMCs. The converter has also been evaluated in terms of the component stress and voltage conversion ratio against some other converters for high power occasions. Moreover, a 2.5MW simulation model and a 1.2kW prototype were constructed for verification.

A non-isolated high-voltage gain dual-input DC/DC converter with a zero voltage turn-off (ZVT) auxiliary circuit has been presented. Two photovoltaic (PV) modules can be connected to the proposed converter with separate maximum power point tracking (MPPT). The cost of whole PV power generation system can be decreased significantly as a single converter is employed instead of two converters. All switches can achieve ZVT by an auxiliary circuit, and turn-off switching losses can be decreased and the efficiency of the converter can be improved. Working principle and performance characteristics of the proposed converter are analysed in detail, a dual-input maximum power point tracking control algorithm has been designed for the proposed converter. An 800 W experimental prototype has been built to verify the theoretical analysis.

The series and parallel arc-faults on the DC-side have different characteristics than that of the AC-side of PV systems and hence require advanced detection strategies. This paper proposes a robust, reliable technique for the detection of different types of DC arc-faults. The method uses a fault detector algorithm called the Decomposed Open-Close Alternating Sequence (DOCAS) using morphological filters. The proposed method detects the existence of an arcing fault by generating spikes at its output. The proposed method is tested for different types of series and parallel DC arc-faults under different levels of irradiance. Simulation results demonstrate that the proposed method maintains the selectivity and distinguishes changes in irradiance and load levels from series and parallel faults effectively.

Coupled inductors can be used to connect cells in parallel in a voltage source inverter to increase both rated power and bandwidth. To successfully implement this strategy it is critical to achieve a balanced contribution to the output current by all paralleled cells. Circulating currents should also be controlled and minimized to prevent additional losses in the switching devices. This paper presents an effective method to achieve current sharing between inverter cells paralleled via magnetically coupled inductors, using a state feedback controller. Experimental results are presented validating the performance of the proposed balancing method.

The capability of a distributed renewable generator (DRG) in providing load low-voltage ride-through (LVRT) is examined. The harnessed renewable power, load demand, and the occurrences of low-voltage incidents are treated as random variables. The probability of successful load LVRT is assessed through the use of a copula function to quantify the stochastic dependency between the load and the renewable power. The analysis is then applied to the case of a series-connected photovoltaic DRG incorporated with capacitor energy storage, wherein the focus is to establish the analytical relationship between the probability of successful load LVRT and the rated power/energy capacities of the DRG capacitor. Determination of the optimal capacities of the DRG capacitor is achieved through maximization of the expected economic benefits obtained from the renewable energy harness and load LVRT minus the cost of the DRG capacitor.

Multilevel Modular Cascade Converters (MMCC) can be used to provide higher effective switching frequencies and reduce harmonic distortion in classical converter problems such as BESS and STATCOM. To successfully implement a MMCC in a STATCOM application it is necessary to balance dc-link voltages of the individual modules and track a reference output current. This work presents master and individual module controls utilizing feedback linearization and sliding mode control. Simulation results demonstrate that the control strategy presented in this paper can balance dc-link voltages of individual modules and provide output current tracking within the first cycle.

This investigation is concerned with the effectiveness of Distributed STATic COMpensators (DSTATCOMs) at providing voltage support in Single Wire Earth Return (SWER) networks. The reason for the focus on SWER lines is the high cost of upgrading them in the traditional way to solve voltage regulation problems that result from load growth in some of the feeders. A number of aspects of DSTATCOM installation and operation have been explored. These include their location, reactive power circulation, reactive power prioritising, four quadrant operation and the timing of installation and operation. It has been possible to derive analytical expressions only for the case of a single Thevenin source equivalent and a single load in parallel with a DSTATCOM. From one of those expressions it was deduced that, on a voltage increment per kVAr basis, DSTATCOMs are most effective as voltage regulators when they are installed at the customer terminals rather than further upstream into the network. This result has been found to apply generally to all practical SWER lines. Another derived expression predicted a peak value of customer terminal voltage when active power (P) and reactive power (Q) are injected by the DSTATCOM at constant kVA (S). This maximum voltage represents a stability limit for the case where DSTATCOMs are controlled to operate at constant kVA. Load flow studies revealed that in general this stability limit exists for all practical SWER lines. To avoid VAr circulation it is proposed that droop control with hysteretic band is used for DSTATCOM operation. The standard Newton-Raphson load flow formulation has been extended to accommodate DSTATCOMs operating under droop control and with operating point on a defined trajectory on the P-Q plane. Four defined trajectories have been investigated under given hourly load demand profile. These are the Q-only scheme, the constant kVA scheme with Q-priority, the load power factor follow scheme and the power factor correction scheme. For each one of those defined trajectories a modified Jacobian had to be derived. Load flow studies were based on each of the modified formulations. The load flow programs were designed to automatically provide a solution for each hour of a 24-hour demand profile representing the worst case peak demand for a particular year in the life of any practical SWER line. The customer DSTATCOM is either left on line, brought on line, left off line or taken off line, depending on the calculated customer voltage. Those special features of the load flow programs allowed them to be used to determine when and at what customer location DSTATCOMs should be installed and what their ratings should be. While the focus of the thesis has been on undervoltage problems; the proposed solutions and algorithms are applicable to overvoltage problems caused by the Ferranti Effect.

Active ripple current reduction method is proposed for isolated DC/AC dual active bridge (DAB) converter to reduce the double grid frequency ripple in the DC current. Unlike those active methods that require extra switches to construct separate ripple reduction circuit, in this method, one or two branches of LC ripple steering circuits are used along with existing full bridge switches in a multiplexing manner. For the purpose of the ripple elimination, unsymmetrical phase shift modulation and duty cycle regulation methods are proposed and applied to both legs of the converter on the primary side of DAB converter. Also a current sharing (CS) scheme is presented to balance the current on both LC ripple steering circuits.

Arc faults in a PV system are difficult to study using models developed for conventional power sources mainly due to non-linear behavior of PV current and its dependence on external factors such as irradiance, shading and maximum power tracking controls. This paper presents a unique model derived from fundamentals of Mayr and Cassie arc models and introducing a hyperbolic tangent function to approximate arc current at near zero gap. Arc impedance widely changes with heat dissipated through arcs periphery. Unique feature of the proposed model is that it takes into account this change of impedance with time which could be used to analyze arcs with changing lengths due to movements of current carrying elements. A test bench has been built with adjustable gap between two electrodes to conduct experiments. Both experimental results and simulation outcomes are presented to verify the proposed model.

A frequency modulation scheme is proposed for a Capacitor-Inductor-Inductor-Capacitor (CLLC) Resonant Dual Active Bridge (RDAB) that relies on dynamic retuning of the resonant capacitors to the switching frequency as it is modulated. The proposed modulation scheme greatly reduces the circulating reactive currents in the High Frequency Link (HFL) by operating at a range of fixed discrete switching frequencies. A Triple Phase Shift (TPS) modulation scheme is used in between the discrete steps of switching frequencies and capacitances. In this paper, a mathematical analysis is presented of the RDAB and the proposed modulation scheme is compared to all of the existing modulation schemes. The CLLC RDAB is implemented in simulation and the simulation results demonstrate the effectiveness of the proposed modulation scheme at decreasing the circulating reactive currents, and therefore, greatly decreasing the conduction losses of the converter at light load, while maintaining its soft switching capability.

Induction motors (IMs) have been extensively used in industrial applications because of their inexpensiveness, ruggedness and reliability. Generally, to improve the performance of IM drives, one position sensor, one DC-link voltage sensor and at least two AC current sensors are necessary. However, failure of any of these sensors can cause degraded system performance or even instability. Consequently, it is very important to develop a sensor fault resilient control system for IMs drives so that continuous and normal operation is maintained even in cases of sensor faults. This study proposes a compact and robust sensor fault detection, isolation and system reconfiguration algorithm based on extended Kalman filter and reduced number of adaptive observers. A comprehensive set of experimental results are provided to verify the effectiveness of the proposed algorithm.

Inductive Power Transfer (IPT) systems have been more and more popular as they offer numerous advantages over conventional wired power transfer systems in terms of convenience, safety, isolation, and flexibility. This paper presents an overview of power converter topologies as well as modulation strategies for IPT systems. Besides, a brief introduction to the overview of fundamental components in IPT systems will also be presented to give a better basic knowledge of IPT systems to the readers.

In the development of control strategies for traction control in railway systems or locomotive applications, the dynamic interaction is known as traction force coefficient between the wheel and the rail must be carefully considered. Identification of the traction force coefficient between a railway wheel and rail track is a challenging task because of the difficulty in its measurement directly. Railway systems experiences wheel slip due to their acceleration and deceleration and also due to rail surfaces. Therefore, the traction force coefficient is an important factor in maintaining high acceleration and braking performance of railway. This study proposes a new approach to estimate the traction force coefficient using a Kalman Filter structured to included unknown input and then utilize the traction force between the wheel and rail where it reaches the maximum traction force level which is an adhesive force. For proper acceleration or braking of the wheel, the driving torque should be kept near to the adhesive level for the desired anti-slip control. Consequently, the motor drive system is required to make an instant and fast torque control to adjust the speed of a railway vehicle. The focus of this research project is to develop a dynamic model of the wheel slip controller that will be subsequently used to design a model for an induction motor driven locomotive.

The improvement of misalignment tolerance is a key challenge for the optimization of wireless power transfer (WPT) systems. WPT coil design plays an imperative role in improving the misalignment tolerance. However, misalignment tolerance needs to be considered along with the dynamics of the receiving coil. This paper presents a coil optimization method to improve misalignment tolerance according to the receiver positioning behavior. A novel figure-of-merit (FOM) is introduced by incorporating maximum efficiency and the probability of alignment (PA). A case study for parameter optimization of circular spiral coils is presented with the use of the proposed FOM.

The more-electric trend is there in almost all the corners of the automotive industry. The same trend is followed by the maritime transportation industry as well and as a result, conventional mechanical transmission based propulsion systems are gradually being overtaken by electric power transmission based propulsion systems. An azimuth thruster driven by an electric motor is a common configuration found in modern electric propulsion systems. Due to the tight speed control and stiff drivetrain in these propulsion systems load transients easily get propagated into the dc-link of the motor drive and subsequently into the upstream power bus as well. These transients can cause disturbances to the other loads connected to the power system. In the worst case, stability of the shipboard power system gets affected by the transients. This paper proposes to use the capacitor-clamped inverter based motor drive itself to absorb such transients and thereby prevent the propagation into the power bus. The efficacy of the proposed concept is verified through computer simulations. Simulation results show that the capacitor-clamped inverter is capable of absorbing load transients without passing them to the upstream power bus.

Battery modelling is a significant component of advanced Battery Management Systems (BMSs). The full electrochemical model of a battery can represent high precision battery behavior during its operation. However, the high computational requirement to solve the coupled nonlinear partial differential equations (PDEs) that define these models limits their applicability in an online BMS, especially for a battery pack containing hundreds of cells. Therefore, a reduced SPM-Three parameter model is proposed in this paper to efficiently model a lithium ion cell with high accuracy in a specific range of cell operation. The reduced model is implemented in a Simulink block for developing an advanced battery modelling tool that can be applied to a wide variety of battery applications.

This study proposes two novel modularised battery systems capable of controlling the power of each module independently, and with inductive interface for convenient battery swapping. The proposed systems aid in overcoming the limitations such as unavailability of electric vehicle (EV) due to battery pack fault and lengthy battery recharging time which largely hampers the adoption of EVs for personal transportation. The proposed systems consist of a plurality of battery modules which are wirelessly coupled to the EV through inductive power transfer technology. The proposed systems are described in detail, and models are presented to analyse their steady-state behaviours. A design guideline for a 24 kWh 80 kW battery micro-pack system is discussed. Performances of the proposed topologies are investigated using simulations. To demonstrate the applicability, prototype systems of 1.5 kW are implemented and tested under various operating conditions. Results convincingly indicate that the proposed systems improve the vehicle's availability under fault condition. Published version

The incorporation of a repeater with a wireless power transfer (WPT) system for the performance improvement is investigated in this paper. Tuning of the self-resonance frequencies of transmitter, receiver and repeater coils is investigated as a promising approach to improve the performance against load variation. Theoretical analysis is presented using equivalent circuit method, and the 2-coil equivalent of WPT system with a repeaters is explored. Numerical results are presented along with experimental results to validate the proposed method.

Several power converter topologies have been presented for Inductive Power Transfer (IPT) systems to generate high frequency current to cite the primary side inductive coils/tracks. This paper proposed the neutral point clamped (NPC) and flying capacitor (FC) multilevel converters based IPT systems which are suitable for high power IPT applications. The modulation strategies for single phase as well as three phase converters are carried out. The simulation results are presented to demonstrate the feasibility of the proposed system.

This paper presents a novel topology for the generation of high voltage pulses that uses both slow and fast solid-state power switches. This topology includes diode-capacitor units in parallel with commutation circuits connected to a positive buck-boost converter. This enables the generation of a range of high output voltages with a given number of capacitors. The advantages of this topology are the use of slow switches and a reduced number of diodes in comparison with conventional Marx generator. Simulations performed for single and repetitive pulse generation and experimental tests of a prototype hardware verify the proposed topology.

PurposeMulti‐level diode‐clamped inverters have the challenge of capacitor voltage balancing when the number of DC‐link capacitors is three or more. On the other hand, asymmetrical DC‐link voltage sources have been applied to increase the number of voltage levels without increasing the number of switches. The purpose of this paper is to show that an appropriate multi‐output DC‐DC converter can resolve the problem of capacitor voltage balancing and utilize the asymmetrical DC‐link voltages advantages.Design/methodology/approachA family of multi‐output DC‐DC converters is presented in this paper. The application of these converters is to convert the output voltage of a photovoltaic (PV) panel to regulate DC‐link voltages of an asymmetrical four‐level diode‐clamped inverter utilized for domestic applications. To verify the versatility of the presented topology, simulations have been directed for different situations and results are presented. Some related experiments have been developed to examine the capabilities of the proposed converters.FindingsThe three‐output voltage‐sharing converters presented in this paper have been mathematically analysed and proven to be appropriate to improve the quality of the residential application of PV by means of four‐level asymmetrical diode‐clamped inverter supplying highly resistive loads.Originality/valueThis paper shows that an appropriate multi‐output DC‐DC converter can resolve the problem of capacitor voltage balancing and utilize the asymmetrical DC‐link voltages advantages and that there is a possibility of operation at high‐modulation index despite reference voltage magnitude and power factor variations.

There is a trade off between a number of output voltage levels and the reliability and efficiency of a multilevel converter. A new configuration of diode-clamped multilevel inverters with a different combination of DC link capacitors voltage has been proposed in this paper. Two different symmetrical and asymmetrical unequal arrangements for a four-level diode-clamped inverter have been compared, in order to find an optimum arrangement with lower switching losses and optimised output voltage quality. The simulation and hardware results for a four-level inverter show that the asymmetrical configuration can obtain more output voltage levels with the same number of components compared with a conventional four-level inverter and this will lead to the reduction of the harmonic content of the output voltage. A new family of multi-output DC-DC converters with a simple control strategy has been utilised as a front-end converter to supply the DC link capacitor voltages for the optimised configuration.

This paper presents a sensorless direct torque control (DTC) scheme for interior permanent magnet synchronous motors (IPMSMs) drives over a wide speed range including very low speeds. The stator flux observer comprises the voltage model augmented by the current model. The position information required by the current model is derived from the examination of the stator current response due to machine saliency. Unlike the signal injection method, the proposed method utilizes only the applied voltage vectors to the machine stator windings. The simulation results presented verify the effectiveness of the proposed approach.

Major advances in power electronics during recent years have prompted considerable interest within the traction community. The capability of new technologies to reduce the AC railway networks' effect on power quality and improve their supply efficiency is expected to significantly decrease the cost of electric rail supply systems. Of particular interest are Static Frequency Converter (SFC), Rail Power Conditioner (RPC), High Voltage Direct Current (HVDC) and Energy Storage Systems (ESS) solutions. Substantial impacts on future feasibility of railway electrification are anticipated. Aurizon, Australia's largest heavy haul railway operator, has recently commissioned the world's first 50Hz/50Hz SFC installation and is currently investigating SFC, RPC, HVDC and ESS solutions. This paper presents a summary of current and emerging technologies with a particular focus on the potential techno-economic benefits.

Proposed in this paper is a low-cost, half-duplex optical communication bus for control signal isolation in modular or multilevel power electronic converters. The concept is inspired by the Local Interconnect Network (LIN) serial network protocol as used in the automotive industry. The proposed communications bus utilises readily available optical transceivers and is suitable for use with low-cost microcontrollers for distributed control of multilevel converters. As a signal isolation concept, the proposed optical bus enables very high cell count modular multilevel cascaded converters (MMCCs) for high-bandwidth, high-voltage and high-power applications. Prototype hardware is developed and the optical bus concept is validated experimentally in a 33-level MMCC converter operating at 120 Vrms and 60 Hz.

Metamaterials (MMs) have been proposed to improve the performance of wireless power transfer (WPT) systems. The performance of identical unit cells having the same transmitter and receiver self-resonance is presented in the literature. This paper presents the optimization of tunable MM for performance improvement in WPT systems. Furthermore, a figure of merit (FOM) is proposed for the optimization of WPT systems with MMs. It is found that both transferred power and power transfer efficiency can be improved significantly by using the proposed FOM and tunable MM, particularly under misaligned conditions.

A switch-mode assisted linear amplifier (SMALA) combining a linear (Class B) and a switch-mode (Class D) amplifier is presented. The usual single hysteretic controlled half-bridge current dumping stage is replaced by two parallel buck converter stages, in a parallel voltage controlled topology. These operate independently: one buck converter sources current to assist the upper Class B output device, and a complementary converter sinks current to assist the lower device. This topology lends itself to a novel control approach of a dead-band at low power levels where neither class D amplifier assists, allowing the class B amplifier to supply the load without interference, ensuring high fidelity. A 20 W implementation demonstrates 85% efficiency, with distortion below 0.08% measured across the full audio bandwidth at 15 W. The class D amplifier begins assisting at 2 W, and below this value, the distortion was below 0.03%. Complete circuitry is given, showing the simplicity of the additional class D amplifier and its corresponding control circuitry.

Multilevel converters can achieve an overall effective switch frequency multiplication and consequent ripple reduction through the cancellation of the lowest order switch frequency terms. This paper investigates the harmonic content and the frequency response of these multimodulator converters. It is shown that the transfer function of uniformly sampled modulators is a bessel function associated with the inherent sampling process. Naturally sampled modulators have a flat transfer function, but multiple switchings per switch cycle will occur unless the input is slew-rate limited. Lower sideband harmonics of the effective carrier frequency and, in uniform converters, harmonics of the input signal also limit the useful bandwidth. Observations about the effect of the number of converters, their type (naturally or uniformly sampled), and the ratio of modulating frequency and switch frequency are made.

A high-frequency-link micro-inverter is proposed for integrating a single photovoltaic panel to a local load or utility grid. The number of power switches is minimized in addition to reduced magnetic components in order to design a low cost, light weight, compact and efficient inverter. A front-end current-fed isolated boost converter is used to integrate the photovoltaic panel to the rest of micro-inverter that consists of a half-wave cycloconverter and half-bridge inverter. The two basic building modules are interconnected via a high voltage DC-link capacitor. A series resonant tank is used to implement soft-switching in the half-bridge inverter and in the half-wave cycloconverter at the grid side. A highly optimized switching scheme is proposed to have soft-switching in all possible power conversion stages. The proposed micro-inverter is simulated using the MATLAB/Simulink Simpower block-set and with PSIM in order to verify the feasibility of the proposed converter and the effectiveness of the proposed switching control scheme.

An electronically-controlled series resonant circuit based micro-inverter with a full-bridge inverter and a half-wave cycloconverter is proposed for single phase distributed photovoltaic (PV) systems rated up to 400W. A series resonant circuit and a high frequency transformer are used to couple the full-bridge inverter and the half-wave cycloconverter. Inductor of the series resonant circuit is used to control output current of the micro-inverter. The proposed current control strategy of the micro-inverter is mathematically analyzed. The proposed micro-inverter is simulated using the MATLAB/PLECS block set in order to verify feasibility of the proposed current control method in series resonant circuit based DC-AC converters. Experimental results are obtained to further validate the proposed current control method.

A photovoltaic micro-inverter with a half-bridge inverter, half-wave cycloconverter and front-end boost converter is proposed with a series resonant circuit. A PV panel is connected to the micro-inverter via the front-end DC-DC converter. The micro-inverter is integrated to the grid by using the half-wave cycloconverter. The Half-wave cycloconverter and the half-bridge inverter are interfaced by using the series resonant tank. The series resonant tank is used to obtain soft switching at turn-on of the half-bridge and the half-wave cycloconverter switches. The front-end DC-DC converter is controlled by using pulse width modulation and it is used to track the maximum power point of the PV panel. Phase shift power modulation is used to obtain grid synchronized 50Hz current. The proposed micro-inverter is analyzed to obtain an expression for average output power over one switching cycle and to identify possible control variables. The micro-inverter is simulated by using the MATLAB/Simulink and PLECS toolboxes. Soft switching behavior of the power switches is analyzed by using the obtained switching wave-forms from the simulation.

Widespread adoption by electricity utilities of Non-Conventional Instrument Transformers, such as optical or capacitive transducers, has been limited due to the lack of a standardised interface and multi-vendor interoperability. Low power analogue interfaces are being replaced by IEC 61850 9 2 and IEC 61869 9 digital interfaces that use Ethernet networks for communication. These ‘process bus’ connections achieve significant cost savings by simplifying connections between switchyard and control rooms; however the in-service performance when these standards are employed is largely unknown. The performance of real-time Ethernet networks and time synchronisation was assessed using a scale model of a substation automation system. The test bed was constructed from commercially available timing and protection equipment supplied by a range of vendors. Test protocols have been developed to thoroughly evaluate the performance of Ethernet networks and network based time synchronisation. The suitability of IEEE Std 1588 Precision Time Protocol (PTP) as a synchronising system for sampled values was tested in the steady state and under transient conditions. Similarly, the performance of hardened Ethernet switches designed for substation use was assessed under a range of network operating conditions. This paper presents test methods that use a precision Ethernet capture card to accurately measure PTP and network performance. These methods can be used for product selection and to assess ongoing system performance as substations age. Key findings on the behaviour of multi-function process bus networks are presented. System level tests were performed using a Real Time Digital Simulator and transformer protection relay with sampled value and Generic Object Oriented Substation Events (GOOSE) capability. These include the interactions between sampled values, PTP and GOOSE messages. Our research has demonstrated that several protocols can be used on a shared process bus, even with very high network loads. This should provide confidence that this technology is suitable for transmission substations.

The IEC 61850 family of standards for substation communication systems was released in the early 2000s and includes IEC 61850-8-1 and IEC 61850-9-2 that enable Ethernet to be used for process-level connections between transmission substation switchyards and control rooms. This paper presents an investigation of process bus protection performance, since the inservice behavior of multifunction process buses is largely unknown. An experimental approach was adopted that used a Real Time Digital Simulator and "live" substation automation devices. The effect of sampling synchronization error and network traffic on transformer differential protection performance was assessed and compared to conventional hard-wired connections. Ethernet was used for all sampled value measurements, circuit breaker tripping, transformer tap-changer position reports, and precision time protocol synchronization of sampled value merging unit sampling. Test results showed that the protection relay under investigation operated correctly with process bus network traffic approaching 100% capacity. The protection system was not adversely affected by synchronizing errors significantly larger than the standards permit, suggesting that these requirements may be overly conservative. This "closed loop" approach, using substation automation hardware, validated the operation of protection relays under extreme conditions. Digital connections using a single shared Ethernet network outperformed conventional hard-wired solutions. Refereed/Peer-reviewed

It can be seen presently widespread electrification of high power vehicular systems such as more electric aircrafts and electric ships. To further improve the efficiency, flexibility and reliability of such systems, zonal DC electric distribution technology is proposed. In most cases, the zonal DC bus is fed by front-end AC/DC voltage source rectifiers and is responsible for supporting many onboard loads with complex dynamic characteristics. Due to the small-signal constant power nature of tightly regulated power electronic loads and the large-signal load variations, stability of the zonal DC bus becomes a major concern. It is clear that conventional PI controllers stabilize the system in a small-signal sense. However, they are ineffective under some large-signal disturbances and load changes. Passivity based control method is known to provides global stability under passive loads, such as resistive loads. Nonetheless, the global stability of voltage regulation with nonlinear loads has not been discussed. This paper proposes a cascaded sliding mode control method with global stability and online observation of load power. Moreover, system stability limit constrained by catastrophic bifurcation is also discussed. Simulation results are provided to verify the proposed method.

Maximum power point tracking (MPPT) is considered as an important strategy to increase the power output from photovoltaic (PV) systems. The presence of multiple maximum power points (MPPs) under partially shaded conditions (PSC) means that traditional MPPT algorithms, such as perturb and observe (P&O) and incremental conductance (IncCond), are unable to effectively track the global MPP. Other existing MPPT methods are either too complex or need additional equipment. In this paper, we propose a simple and efficient hybrid MPPT algorithm for PV systems working under PSC. It combines the advantages of P&O (or IncCond) and artificial neural network (ANN)-based MPPT methods, and features a relatively lower cost, fast response, and simple structure. In this hybrid MPPT, the ANN is used to initially categorize the power based on the irradiance pattern. Based on the classified category, an initial reference duty ratio is determined. Subsequently, a conventional MPPT algorithm (such as P&O or IncCond) is used to search near the global MPP. Finally, the system is able to accurately determine the global MPP which consequently increases the power output from the PV array. The effectiveness of the proposed hybrid MPPT, under various shading patterns, is verified using both simulations and an experimental setup.

Matrix converter (MC) based grid connected bi-directional inductive power transfer (BD-IPT) systems are preferable for numerous applications such as electric vehicle (EV) charging and vehicle-to-grid (V2G) systems due to their single-stage grid integration as opposed to two-stage grid integration of conventional BD-IPT systems. However MC based BD-IPT systems essentially produce harmonics which can have adverse effects on power quality of the utility grid. This paper presents a new control technique, through which the grid side harmonic distortion of MC based BD-IPT systems can be improved. A theoretical analysis is presented with simulations to show that the proposed approach is viable, and results suggest that the presented technique improves the power quality of the system significantly by minimizing the grid side harmonic distortion.

This paper proposes an improved control of rotor side and load side converters with repetitive control in order to compensate the harmonic components in the stator voltage and current of the doubly-fed induction generator (DFIG) when connected with non-linear loads. The non-linear loads results in distorted stator voltage and current with subsequent power quality degradation and electromagnetic torque pulsations of DFIGs. The distorted stator voltage and current are compensated by the proposed hybrid control scheme with repetitive control (RC) based PI controller (PIRC). The harmonic components of different orders and negative sequence component of the stator voltage can be rejected using a single PIRC while most of the other alternative harmonic compensators require separate controllers for damping these components. The PIRC is applied in rotor side converter (RSC) for the purpose of stator voltage compensation and in line side converter (LSC) for stator current compensation, respectively. The simulation results are given and they show that the PIRC control scheme can eliminate stator voltage and current harmonic of stand-alone DFIG effectively.

State of Charge (SoC) imbalance between battery modules is unavoidable in high capacity Battery Energy Storage Systems (BESS). This paper investigates a module level SoC balancing control in cascaded H-bridge inverter (CHB) based BESS using multi-dimensional modulation technique. Multi-dimensional modulation is a generalized modulation strategy for cascaded H-bridge inverters. With the proposed control strategy, SoC can be equalized between the battery modules in a phase leg of CHB. The performance of the proposed control strategy under faulty cell operation is also studied. The multi-dimensional modulation strategy and the SoC balancing control are explained and the simulation results are given in this paper.

The use of artificial neural networks (ANNs) to identify and control induction machines is proposed. Two systems are presented: a system to adaptively control the stator currents via identification of the electrical dynamics, and a system to adaptively control the rotor speed via identification of the mechanical and current-fed system dynamics. Both systems are inherently adaptive as well as self-commissioning. The current controller is a completely general nonlinear controller which can be used together with any drive algorithm. Various advantages of these control schemes over conventional schemes are cited, and the combined speed and current control scheme is compared with the standard vector control scheme. >

A novel concept of producing high dc voltage for pulsed-power applications is proposed in this paper. The topology consists of an LC resonant circuit supplied through a tuned alternating waveform that is produced by an inverter. The control scheme is based on the detection of variations in the resonant frequency and adjustment of the switching signal patterns for the inverter to produce a square waveform with exactly the same frequencies. Therefore the capacitor voltage oscillates divergently with an increasing amplitude. A simple one-stage capacitor-diode voltage multiplier (CDVM) connected to the resonant capacitor then rectifies the alternating voltage and gives a dc level equal to twice the input voltage amplitude. The produced high voltage appears then in the form of high-voltage pulses across the load. A basic model is simulated by Simulink platform of MATLAB and the results are included in the paper.

This paper details the implementation and trialling of a prototype in-bucket bulk density monitor on a production dragline. Bulk density information can provide feedback to mine planning and scheduling to improve blasting and consequently facilitating optimal bucket sizing. The bulk density measurement builds upon outcomes presented in the AMTC2009 paper titled ‘Automatic In-Bucket Volume Estimation for Dragline Operations’ and utilises payload information from a commercial dragline monitor. While the previous paper explains the algorithms and theoretical basis for the system design and scaled model testing this paper will focus on the full scale implementation and the challenges involved.

Ethernet is a key component of the standards used for digital process buses in transmission substations, namely IEC 61850 and IEEE Std 1588-2008 (PTPv2). These standards use multicast Ethernet frames that can be processed by more than one device. This presents some significant engineering challenges when implementing a sampled value process bus due to the large amount of network traffic. A system of network traffic segregation using a combination of Virtual LAN (VLAN) and multicast address filtering using managed Ethernet switches is presented. This includes VLAN prioritisation of traffic classes such as the IEC 61850 protocols GOOSE, MMS and sampled values (SV), and other protocols like PTPv2. Multicast address filtering is used to limit SV/GOOSE traffic to defined subsets of subscribers. A method to map substation plant reference designations to multicast address ranges is proposed that enables engineers to determine the type of traffic and location of the source by inspecting the destination address. This method and the proposed filtering strategy simplifies future changes to the prioritisation of network traffic, and is applicable to both process bus and station bus applications. © 2011 IEEE. Refereed/Peer-reviewed

Proposed transmission smart grids will use a digital platform for the automation of substations operating at voltage levels of 110 kV and above. The IEC 61850 series of standards, released in parts over the last ten years, provide a specification for substation communications networks and systems. These standards, along with IEEE Std 1588-2008 Precision Time Protocol version 2 (PTPv2) for precision timing, are recommended by the both IEC Smart Grid Strategy Group and the NIST Framework and Roadmap for Smart Grid Interoperability Standards for substation automation. IEC 61850-8-1 and IEC 61850-9-2 provide an inter-operable solution to support multi-vendor digital process bus solutions, allowing for the removal of potentially lethal voltages and damaging currents from substation control rooms, a reduction in the amount of cabling required in substations, and facilitates the adoption of non-conventional instrument transformers (NCITs). IEC 61850, PTPv2 and Ethernet are three complementary protocol families that together define the future of sampled value digital process connections for smart substation automation. This paper describes a specific test and evaluation system that uses real time simulation, protection relays, PTPv2 time clocks and artificial network impairment that is being used to investigate technical impediments to the adoption of SV process bus systems by transmission utilities. Knowing the limits of a digital process bus, especially when sampled values and NCITs are included, will enable utilities to make informed decisions regarding the adoption of this technology.

IEC Technical Committee 57 (TC57) published a series of standards and technical reports for “Communication networks and systems for power utility automation” as the IEC 61850 series. Sampled value (SV) process buses allow for the removal of potentially lethal voltages and damaging currents inside substation control rooms and marshalling kiosks, reduce the amount of cabling required in substations, and facilitate the adoption of non-conventional instrument transformers. IEC 61850-9-2 provides an inter-operable solution to support multi-vendor process bus solutions. A time synchronisation system is required for a SV process bus, however the details are not defined in IEC 61850-9-2. IEEE Std 1588-2008, Precision Time Protocol version 2 (PTPv2), provides the greatest accuracy of network based time transfer systems, with timing errors of less than 100 ns achievable. PTPv2 is proposed by the IEC Smart Grid Strategy Group to synchronise IEC 61850 based substation automation systems. IEC 61850-9-2, PTPv2 and Ethernet are three complementary protocols that together define the future of sampled value digital process connections in substations. The suitability of PTPv2 for use with SV is evaluated, with preliminary results indicating that steady state performance is acceptable (jitter < 300 ns), and that extremely stable grandmaster oscillators are required to ensure SV timing requirements are met when recovering from loss of external synchronisation (such as GPS).

A novel H-bridge multilevel pulsewidth modulation converter topology based on a series connection of a high-voltage diode-clamped inverter and a low-voltage conventional inverter is proposed in this paper. A dc link voltage arrangement for the new hybrid and asymmetric solution is presented to have a maximum number of output voltage levels by preserving the adjacent switching vectors between voltage levels. Hence, a 15-level hybrid converter can be attained with a minimum number of power components. A comparative study has been carried out to present high performance of the proposed configuration to approach a very low total harmonic distortion of voltage and current, which leads to the possible elimination of the output filter. Regarding the proposed configuration, a new cascade inverter is verified by cascading an asymmetrical diode-clamped inverter, in which 19 levels can be synthesized in output voltage with the same number of components. To balance the dc link capacitor voltages for the maximum output voltage resolution as well as synthesize asymmetrical dc link combination, a new multi-output boost converter is utilized at the dc link voltage of a seven-level H-bridge diode-clamped inverter. Simulation and hardware results based on different modulations are presented to confirm the validity of the proposed approach to achieve a high-quality output voltage.

This paper presents a high-voltage pulsed-power system based on low-voltage switch-capacitor units that are connected to a current source for several applications such as plasma systems. A modified positive buck-boost converter topology is used to utilize the current source concept, and a series of low-voltage switch-capacitor units is connected to the current source in order to provide a high voltage with a high voltage stress (dv/dt) as demanded by the loads. This pulsed-power converter is flexible in terms of energy control because the stored energy in the current source can be adjusted by changing the current magnitude to significantly improve the efficiency of various systems with different requirements. The output-voltage magnitude and stress (dv/dt) can be controlled by a proper selection of components and control algorithm to turn on and off the switching devices.