Multiphase induction machine modelling represents a crucial research topic for both machine control and performance evaluation purposes. Generally, multiphase induction machines are preferably ...modelled using the vector space decomposition technique with some assumptions to simplify the mathematical model. However, different sources of non-linearities, including low order harmonics mapped to secondary subspaces, cross-coupling saturation and iron losses result in a notable deviation from the experimentally measured waveforms. Furthermore, considering full symmetry amongst motors phases seems to be a rather idealistic assumption. Fractional order modelling has recently emerged as a promising mathematical technique to model highly nonlinear electrical and mechanical systems. This paper proposes an improved vector space decomposition (VSD)-based fractional order model of an asymmetrical six-phase induction machine under both healthy and open phase fault conditions with different neutral arrangements. The appropriate differentiation orders have been obtained by optimizing the error function between simulated and experimental waveforms. The results are compared with the conventional integral order-based model. Experimental validation has been carried out using a 1.5Hp prototype induction machine.
With the accelerated development in semiconductor power devices along with the dictated rigorous reliability standards in some industrial sectors, the application of a medium-voltage high-power ...multiphase induction machine with multiple three-phase windings is now considered as a leading technology in high-power safety-critical applications. This paper proposes a parameter-independent postfault control scheme for an asymmetrical six-phase induction machine based on simple scalar V/f control, which can successfully ensure the most common postfault scenarios used in this respect, namely, equal stator copper loss and minimum copper loss modes. Moreover, the proposed controller can effectively be used in either open-loop or closed-loop speed control modes. The proposed controller is experimentally validated using a 1.5-kW prototype induction machine. The effect of the neutral arrangement on the dynamic performance is also explored.
This paper proposes a multiport DC-DC converter for EV fast-charging stations. The proposed converter is comprised of Ring-Connected Dual Active Bridge (RCDAB) DC-DC converters, where the connection ...point between every two adjacent DABs provides a DC port. Bypass switches are added to each DAB to eliminate unnecessary power processing stages in the event of idle ports (no EVs) (open circuit ports). The nature of the ring connection of the RCDAB theoretically allows infinite internal power flow solutions within the ring to satisfy a certain power flow scenario at the DC ports, hence, the optimal power flow solution can be selected to minimize total RMS current and losses. Single-phase shift control is applied to this optimization problem to make it simple. A novel closed-loop control scheme using Bisection optimization is developed to minimize the total RMS current. A control-hardware-in-the-loop (CHiL) validation is carried out for a 5-port network of the proposed topology to investigate the converter efficiency and fault tolerance/availability characteristics. Also, an experimental hardware validation is implemented for a 3-port network where different scenarios for power flow and faults are performed. Finally, a comparative discussion between the proposed topology and other multiport topologies in literature is presented revealing the superior performance of the RCDAB topology.
Power grid pattern is expected to evolve from generator-based power systems towards converter-based systems in the forthcoming decades. Therefore, grid-forming converters will be pertinent to ...interconnected power grids in pursuance of enhancement their resilience against disturbances. This paper introduces a new efficient damping control method for grid-forming converters that provides a smooth power modulation and an efficient damping response against frequency and voltage deviations. First, an averaged state-space representation for a grid forming application in dq synchronization frame is derived. Based on this model, a new hybrid damping controller, including the concept of state feedback control and PI control, is proposed to address the main issues in existing controllers. The state feedback controller is optimally designed using a linear-quadratic regulator (LQR) approach to optimize the system performance. Moreover, the PI controller is optimally designed using the pattern search algorithm. The proposed damping control method integrates optimally between the control loops through a mapping matrix to rapidly synchronize with the grid and efficiently damp the oscillations. Simulations are carried out to prove the proposed method robustness. Finally, a comparative study using controller hardware-in-the-loop (CHiL) is employed against conventional system to validate the proposed damping method.
This paper proposes a new family of discontinuous PWM strategies to control the quasi-Z-source nine-switch inverters (qZS-NSI). The presented strategies provide buck and boost inversion capabilities, ...and suitable for common-frequency and different-frequency modes of operation. Accordingly, two different shoot-through (ST) approaches are introduced and compared. The first approach uses three-leg ST, while the second uses single-leg ST to reduce the number of switching commutations, therefore minimizing switching losses. Both approaches can be implemented using simple-boost (SB) and maximum boost (MB) control methods. The operating principles, performance criteria, and PWM modulator of each scheme are introduced. Compared to the conventional PWM technique for the same output voltage gains, the proposed schemes ensure continuous input current with minimum ripples, and the voltage stresses on the switching devices and capacitors could be reduced in the proposed MB control schemes. Moreover, the effective switching frequency of upper and lower switches of all schemes is fixed and could be reduced by 1/3 from the switching frequency of the conventional technique of the qZS-NSI, while only the single-leg ST schemes ensure minimum effective switching frequency of the middle switches. The proposed modulation strategies are digitally implemented and tested on the LAUNCHXL-F28379D DSP. The feasibility of the proposed modulation schemes is confirmed via simulation and experimental results, which show good agreement with the theoretical analysis. Moreover, the presented strategies can be applied to other types of Z-source NSIs.
Multiphase winding configurations have gained significant attention in high-performance variable speed drives and wind energy conversion systems (WECS) owing to their myriad advantages. In the ...available literature, various multiphase winding layouts have been designed aiming at boosting the machine performance to meet the requirements of the proposed applications. Ultimately, this paper surveyed the state-of-the-art in the available multiphase winding layouts proposed for various innovative applications. Various types of windings were discussed, while investigating their advantages and limitations. This typically considers the winding layouts employed in multiphase induction motors (IMs) and permanent magnet (PM) machines with prime phase and multiple three-phase orders. This study extensively provides innovative winding arrangements that offer better machine characteristics in terms of torque density, efficiency, and fault-tolerance capability. Moreover, the construction of multiphase machines with general <inline-formula> <tex-math notation="LaTeX">n </tex-math></inline-formula>-phase using standard three-phase stator frames has been elaborated. This latter technique obviates the basic necessity of special stator frames with a prime number of phases. Finally, this paper sheds light on the commercial applications that include multiphase winding layouts.
Due to simplicity, efficiency, and the ability to accommodate energy storage devices, DC distribution networks have been seen as an optimal alternative to AC distribution networks, especially aboard ...future electric ships. The emerging distribution DC system entails new control and management techniques. Therefore, an integrated DC power distribution network aboard an electric ship is selected as the case study in this paper. To meet the requirements of such a large-scale mobile power system, a multiport solid-state transformer (SST) based on silicon carbide (SiC) switches/MOSFETs is proposed. Thus, the system embodiment can significantly be reduced. Moreover, at the DC distribution level, a high penetration of renewable generation with energy storage is allowed and a six-phase asymmetrical induction machine (IM) can directly be integrated. Simulations have been conducted based on a 2 MW shipboard distribution network. The effects of the propulsion system dynamics on the SST are highlighted as well. Finally, a 2 kW lab-scale prototype has been implemented to validate the theoretical findings.
To facilitate the automated online monitoring of power plants, a systematic and qualitative strategy for anomaly detection is presented. This strategy is essential to provide credible reasoning on ...why and when an empirical versus hybrid (i.e., physics-supported) approach should be used and to determine the ideal mix of these two approaches for a defined anomaly detection scope. Empirical methods are usually based on pattern, statistical, and causal inference. Hybrid methods include the use of physics models to train and test data methods, reduce data dimensionality, reduce data-model complexity, augment data, and reduce empirical uncertainty; hybrid methods also include the use of data to tune physics models. The presented strategy is driven by key decision points related to data relevance, simple modeling feasibility, data inference, physics-modeling value, data dimensionality, physics knowledge, method of validation, performance, data availability, and suitability for training and testing, cause-effect, entropy inference, and model fitting. The strategy is demonstrated through a pilot use case for the application of anomaly detection to capture a valve packing leak at the high-pressure coolant injection system of a nuclear power plant.
Accurately estimating the state-of-charge (SOC) of lithium-ion batteries (LIBs) in electric vehicles is a challenging task due to the complex dynamics of the battery and the varying operating ...conditions. To address this, this paper proposes the establishment of an Industrial Internet-of-Things (IIoT)-based digital twin (DT) through the Microsoft Azure services, incorporating components for data collection, time synchronization, processing, modeling, and decision visualization. Within this framework, the readily available measurements in the LIB module, including voltage, current, and operating temperature, are utilized, providing advanced information about the LIBs’ SOC and facilitating accurate determination of the electric vehicle (EV) range. This proposed data-driven SOC-estimation-based DT framework was developed with a supervised voting ensemble regression machine learning (ML) approach using the Azure ML service. To facilitate a more comprehensive understanding of historical driving cycles and ensure the SOC-estimation-based DT framework is accurate, this study used three application programming interfaces (APIs), namely Google Directions API, Google Elevation API, and OpenWeatherMap API, to collect the data and information necessary for analyzing and interpreting historical driving patterns, for the reference EV model, which closely emulates the dynamics of a real-world battery electric vehicle (BEV). Notably, the findings demonstrate that the proposed strategy achieves a normalized root mean square error (NRMSE) of 1.1446 and 0.02385 through simulation and experimental studies, respectively. The study’s results offer valuable insights that can inform further research on developing estimation and predictive maintenance systems for industrial applications.
An interline dynamic voltage restorer (IDVR) is invariably employed in distribution systems to mitigate voltage sag/swell problems. An IDVR merely consists of several dynamic voltage restorers (DVRs) ...sharing a common dc link connecting independent feeders to secure electric power to critical loads. While one of the DVRs compensates for the local voltage sag in its feeder, the other DVRs replenish the common dc-link voltage. For normal voltage levels, the DVRs should be bypassed. Instead of bypassing the DVRs in normal conditions, this paper proposes operating the DVRs, if needed, to improve the displacement factor (DF) of one of the involved feeders. DF improvement can be achieved via active and reactive power exchange (PQ sharing) between different feeders. To successfully apply this concept, several constraints are addressed throughout the paper. Simulation and experimental results elucidate and substantiate the proposed concept.
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