Pulse Tripling Circuit and Twelve Pulse Rectifier Combination for Sinusoidal Input Current

In this paper, a novel pulse tripling circuit (PTC) is suggested, to upgrade a polygon autotransformer 12-pulse rectifier (12-PR) to a 36-pulse rectifier (36-PR) with a low power rating. The kVA rating of the proposed PTC is lower compared to the conventional one (about 1.57% of load power). Simulation and experimental test results show that the total harmonic distortion (THD) of the input current of the suggested 36-PR is less than 3%, which meets the IEEE 519 requirements. Also, it is shown that in comparison with other multi-pulse rectifiers (MPR), it is cost-effective, its power factor is near unity and its rating is about 24% of the load rating. Therefore, the proposed 36-PR can be considered as a practical solution for industrial applications

An Improved 24-Pulse Rectifier for Harmonic Mitigation in More Electric Aircraft

Abstract To increase the power rating and reduce the cost and complexity of a multi‐pulse rectifier (MPR), it is well known that the pulse number must be increased. In some practical cases, a 12‐pulse rectifier (12PR) is suggested as a good solution considering its relatively simple structure and low weight. However, 12‐pulse rectifiers cannot technically meet the standards of harmonic distortion requirements for some industrial applications, and therefore they must be used along with output filters. Two cost‐effective 24‐pulse rectifiers (24PRs) are suggested in the article, which consist of a polygon autotransformer 12PR and two pulse doubling circuits (PDCs) at dc link. The first PDC (PDC1) is based on an inter‐phase transformer (IPT) with a step‐up secondary winding, and the second one (PDC2) is based on an IPT with a step‐down secondary winding. To show the advantages of the proposed combinations compared with other solutions, simulation results are used, and also a prototype is implemented to evaluate and verify the simulation results. The simulation and experimental test results show that the total harmonic distortion (%THD) of the input current for the 12PR with PDC1 is less than 3.67%, and the 12PR with PDC2 is less than 1.45%, which meets the IEEE 519 and DO‐160G requirements. Also, it is shown that in comparison with other solutions, the proposed two configurations are cost‐effective, power factor is near unity, rating is almost 29% of the load rating, and the efficiency is almost 97.5%, which makes them a practical solution for more electric aircraft

Comparative Analysis of Two Novel Passive Harmonic Suppression Circuits for Industrial Applications

The 12-pulse diode rectifier (12-PDR) fails to comply with the limits of total harmonic distortion (THD) of supply current to be less than 5% specified in the IEEE Standard 519. Passive harmonic suppression circuits (PHSCs) have been observed to be a viable and cost-effective solution to improve the THD of AC-mains current at a reduced cost. PHSCs increase the number of rectification pulses without leading to significant changes in the installations and yield harmonic reduction in both AC and DC sides. This paper presents a comparative analysis of two novel PHSCs connected at the DC-bus of 12-PDR. One is PHSC-I based on four tapped reactors (FTRs) and four auxiliary diodes; the other is PHSC-II, with two tapped reactors (TTRs) and two auxiliary diodes. The operation modes and optimal parameters of both PHSCs are analyzed with similar inputs (AC side) and outputs (DC side). Both 12-PDR are connected to the same AC source as input, and both PHSCs supplied similar DC loads at their outputs, thus leading to an accurate and fair comparison between the two PHSCs. The results show that the input current THD of a 12-PDR with PHSC-II is lower than that of a PHSC-I and lower than existing passive harmonic suppression circuits. In addition, PHSC-II leads to lower connection losses, current stress, and cost than PHSC-I, so in industrial applications that require low input current THD, low connection losses/current stress, and low cost, PHSC-II is highly recommended

Power Quality in Electrified Transportation Systems

"Power Quality in Electrified Transportation Systems" has covered interesting horizontal topics over diversified transportation technologies, ranging from railways to electric vehicles and ships. Although the attention is chiefly focused on typical railway issues such as harmonics, resonances and reactive power flow compensation, the integration of electric vehicles plays a significant role. The book is completed by some additional significant contributions, focusing on the interpretation of Power Quality phenomena propagation in railways using the fundamentals of electromagnetic theory and on electric ships in the light of the latest standardization efforts

Advances in the Field of Electrical Machines and Drives

Electrical machines and drives dominate our everyday lives. This is due to their numerous applications in industry, power production, home appliances, and transportation systems such as electric and hybrid electric vehicles, ships, and aircrafts. Their development follows rapid advances in science, engineering, and technology. Researchers around the world are extensively investigating electrical machines and drives because of their reliability, efficiency, performance, and fault-tolerant structure. In particular, there is a focus on the importance of utilizing these new trends in technology for energy saving and reducing greenhouse gas emissions. This Special Issue will provide the platform for researchers to present their recent work on advances in the field of electrical machines and drives, including special machines and their applications; new materials, including the insulation of electrical machines; new trends in diagnostics and condition monitoring; power electronics, control schemes, and algorithms for electrical drives; new topologies; and innovative applications

Investigation of domestic level EV chargers in the Distribution Network: An Assessment and mitigation solution

This research focuses on the electrification of the transport sector. Such electrification could potentially pose challenges to the distribution system operator (DSO) in terms of reliability, power quality and cost-effective implementation. This thesis contributes to both, an Electrical Vehicle (EV) load demand profiling and advanced use of reactive power compensation (D-STATCOM) to facilitate flexible and secure network operation. The main aim of this research is to investigate the planning and operation of low voltage distribution networks (LVDN) with increasing electrical vehicles (EVs) proliferation and the effects of higher demand charging systems. This work is based on two different independent strands of research. Firstly, the thesis illustrates how the flexibility and composition of aggregated EVs demand can be obtained with very limited information available. Once the composition of demand is available, future energy scenarios are analysed in respect to the impact of higher EVs charging rates on single phase connections at LV distribution network level. A novel planning model based on energy scenario simulations suitable for the utilization of existing assets is developed. The proposed framework can provide probabilistic risk assessment of power quality (PQ) variations that may arise due to the proliferation of significant numbers of EVs chargers. Monte Carlo (MC) based simulation is applied in this regard. This probabilistic approach is used to estimate the likely impact of EVs chargers against the extreme-case scenarios. Secondly, in relation to increased EVs penetration, dynamic reactive power reserve management through network voltage control is considered. In this regard, a generic distribution static synchronous compensator (D-STATCOM) model is adapted to achieve network voltage stability. The main emphasis is on a generic D-STATCOM modelling technique, where each individual EV charging is considered through a probability density function that is inclusive of dynamic D-STATCOM support. It demonstrates how optimal techniques can consider the demand flexibility at each bus to meet the requirement of network operator while maintaining the relevant steady state and/or dynamic performance indicators (voltage level) of the network. The results show that reactive power compensation through D-STATCOM, in the context of EVs integration, can provide continuous voltage support and thereby facilitate 90% penetration of network customers with EV connections at a normal EV charging rate (3.68 kW). The results are improved by using optimal power flow. The results suggest, if fast charging (up to 11 kW) is employed, up to 50% of network EV customers can be accommodated by utilising the optimal planning approach. During the case study, it is observed that the transformer loading is increased significantly in the presence of D-STATCOM. The transformer loading reaches approximately up to 300%, in one of the contingencies at 11 kW EV charging, so transformer upgrading is still required. Three-phase connected DSTATCOM is normally used by the DSO to control power quality issues in the network. Although, to maintain voltage level at each individual phase with three-phase connected device is not possible. So, single-phase connected D-STATCOM is used to control the voltage at each individual phase. Single-phase connected D-STATCOM is able maintain the voltage level at each individual phase at 1 p.u. This research will be of interest to the DSO, as it will provide an insight to the issues associated with higher penetration of EV chargers, present in the realization of a sustainable transport electrification agenda

Emerging Converter Topologies and Control for Grid Connected Photovoltaic Systems

Continuous cost reduction of photovoltaic (PV) systems and the rise of power auctions resulted in the establishment of PV power not only as a green energy source but also as a cost-effective solution to the electricity generation market. Various commercial solutions for grid-connected PV systems are available at any power level, ranging from multi-megawatt utility-scale solar farms to sub-kilowatt residential PV installations. Compared to utility-scale systems, the feasibility of small-scale residential PV installations is still limited by existing technologies that have not yet properly address issues like operation in weak grids, opaque and partial shading, etc. New market drivers such as warranty improvement to match the PV module lifespan, operation voltage range extension for application flexibility, and embedded energy storage for load shifting have again put small-scale PV systems in the spotlight. This Special Issue collects the latest developments in the field of power electronic converter topologies, control, design, and optimization for better energy yield, power conversion efficiency, reliability, and longer lifetime of the small-scale PV systems. This Special Issue will serve as a reference and update for academics, researchers, and practicing engineers to inspire new research and developments that pave the way for next-generation PV systems for residential and small commercial applications

Shipboard electrification : emission reduction and energy control

Phd ThesisThe application of green technology to marine transport is high on the sector’s agenda, both for environmental reasons, as well as the potential to positively impact on ship operator running costs. In this thesis, electrical technologies and systems as enablers of green vessels were examined for reducing emissions and fuel consumption in a number of case studies, using computer based models and simulations, coupled with real operational data. Bidirectional auxiliary drives were analysed while providing propulsion during low speed manoeuvring, coupling an electrical machine with power electronic converter and feeding power to the propulsion system from the auxiliary generators. Models were built to enable quantification of losses in various topologies and machine setups, showing how permanent magnet machines compared to induction machines, as well as examining different losses in different topologies. Another examination of topologies was performed for onshore power supply systems, where a number of different network configurations were modelled and examined based on the visiting profile for a particular port. A Particle Swarm Optimisation algorithm was developed to identify optimal configurations considering both capital costs as well as operational efficiency. This was additionally coupled with the consideration of shore-based LNG generation giving a hybrid onshore power supply configuration. Hybrid systems on vessels are more complex in terms of energy management, particularly with on-board energy storage. Particle Swarm Optimisation was applied to a model of a hybrid shipboard power system, optimising continuously for the greenest configuration during the ship’s voyage. This was developed into a generic and scalable Energy Management System, with the objective of minimising fuel consumption, and applied to a case study

Transmissão HVDC-ICC e retificação industrial: uma abordagem empregando novas topologias de conversores de 24 e 48–pulsos de alto desempenho para mitigação harmônica

Power quality improvement, reliability and availability of electrical power are significant concerns in power systems. In this context, multi-pulse converters are interface devices between the AC electrical system and the DC link, widely used in HVDC–TS (HVDC Transmission System) and industrial rectification of very high currents to meet harmonic requirements on both the AC and DC sides of the converter system. This thesis proposes 24 and 48–pulse converter structures for reducing AC and DC filters in conventional HVDC–TS and for excellent harmonic mitigation in industrial rectification, respectively, using special three-winding transformers with ZZ–Y–D (ZigZag–Wye–Delta) or DE–Y–D (Extended delta–Wye–Delta) connection. To prove the feasibility and applicability of both proposed prototypes, computational simulations, under certain established operating conditions, are carried out in Matlab/Simulink to verify the theoretical studies carried out with the help of the MathCad program. Finally, a reduced-scale prototype implementation is performed and tested according to available laboratory resources to validate the proposed converter systems. According to the developed analyses, the results obtained showed a theoretical-experimental consistency in terms of power quality improvement and confirmed the feasibility and applicability of SC–24P (24–Pulse System Converter) and SC–48P (48–Pulse System Converter) proposed.A melhoria da qualidade de energia, a confiabilidade e a disponibilidade da energia elé- trica são questões bastante preocupantes na área de sistemas elétricos de potência. Neste contexto, os conversores multi-pulsos constituem dispositivos de interface entre o sistema elétrico CA e o barramento CC, amplamente empregados em ST–HVDC (Sistema de Transmissão HVDC) e em retificação industrial de altíssimas correntes para atender aos requisitos harmônicos tanto no lado CA quanto no lado CC do sistema conversor. Esta tese propõe estruturas conversoras de 24 e 48–pulsos para redução de filtros CA e CC em ST–HVDC convencional e para excelente mitigação harmônica em retificação industrial, respectivamente usando-se transformadores especiais de três enrolamentos com conexão ZZ–Y–D (ZigueZague–Estrela–Delta) ou DE–Y–D (Delta Estendido–Estrela–Delta). Em seguida, no intuito de se comprovar a viabilidade e aplicabilidade de ambos os protótipos propostos, simulações computacionais, sob determinadas condições de operação estabelecidas, são realizadas em Matlab/Simulink para verificar os estudos teóricos feitos com o auxílio do programa MathCad. Por fim, para validar os sistemas conversores propostos, uma implementação de protótipos em escala reduzida é executada e testada de acordo com os recursos laboratoriais disponíveis. Os resultados obtidos em termos de melhoria da qualidade de energia, conforme as análises desenvolvidas, mostraram uma consistência teórica-experimental e confirmaram a viabilidade e aplicabilidade do SC–24P (Sistema Conversor de 24–Pulsos) e SC–48P (Sistema Conversor de 48–Pulsos) propostos