Design and simulation of techniques for mitigation of harmonic distortion in a three-phase rectifier

Rectifiers are electrical devices that receive an alternating signal and deliver a direct current signal at their output, this process by which they transform one type of energy to another is known as rectification. This type of device incorporates a phenomenon called harmonic distortion into the electrical network, which consists of malformations presented in the waveform of the alternating signal from which it feeds, which generate unwanted effects on electrical systems. Because of this, this work presents the combination of two harmonic distortion mitigation strategies (12-pulse multilevel converter and harmonic frequency tuned filtering stage) in order to reduce total harmonic distortion levels generated by a three-phase rectifier. © Published under licence by IOP Publishing Ltd

Design of Proportional-Resonant Control for Current Harmonic Compliance in Electric Railway Power Systems

This paper presents the process of designing proportional-resonant controller for a four-quadrant rectifier in electric railway traction system. In the context of ever-stricter power quality and electromagnetic compatibility standards in electric railway power systems, developers of electric locomotives need to adapt with new ways to comply. This paper develops on the process of designing a four-quadrant rectifier proportional-resonant control for mitigation of low frequency current harmonic distortion, a novel method in the field of railway EMC. The control parameters are determined through analytical modeling of the rectifier through transfer functions. For the purpose of studying the harmonic distortion mitigation effects, only the current control loop was modeled and designed. The modeling starts with simplification of the model via large-signal modeling of the power converter. The parameters of the circuit then were used to develop the transfer functions, and select the appropriate parameter values of the current loop plant. The control loop and parameters were evaluated on test locomotive to validate the control, with results confirming the improved impact on the electromagnetic compatibility and conformity to regulation

Design of Proportional-Resonant Control for Current Harmonic Compliance in Electric Railway Power Systems

This paper presents the process of designing proportional-resonant controller for a four-quadrant rectifier in electric railway traction system. In the context of ever-stricter power quality and electromagnetic compatibility standards in electric railway power systems, developers of electric locomotives need to adapt with new ways to comply. This paper develops on the process of designing a four-quadrant rectifier proportional-resonant control for mitigation of low frequency current harmonic distortion, a novel method in the field of railway EMC. The control parameters are determined through analytical modeling of the rectifier through transfer functions. For the purpose of studying the harmonic distortion mitigation effects, only the current control loop was modeled and designed. The modeling starts with simplification of the model via large-signal modeling of the power converter. The parameters of the circuit then were used to develop the transfer functions, and select the appropriate parameter values of the current loop plant. The control loop and parameters were evaluated on test locomotive to validate the control, with results confirming the improved impact on the electromagnetic compatibility and conformity to regulation

Unified Control Strategy for Microgrid Solid-State Transformers

Solid-state transformers (SST) are particularly useful components in distributed generation systems (DG). This research approaches the control of the SST in a more comprehensive and an organized way. It proposes a compact, versatile and an efficient unified control strategy. This proposal gives rise to three more proposals. i) A method to mitigate the current harmonic distortion which is uniquely software-based and ii) An efficient low-voltage ride-through (LVRT) scheme. Both of those functions come at no extra cost using the proposed unified control scheme. These proposals further demonstrate the proposed strategys ability to accommodate further features and modifications. A further contribution to this research addresses the unbalanced load conditions. It proposes a simple, cost-free modification to a resonant filter - making it suitable for the proposed control strategy thus maintaining its simplicity without compromising its practicality. All the proposals of this research have been validated through simulation in Simulink

Unified Control Strategy for Microgrid Solid-State Transformers

Solid-state transformers (SST) are particularly useful components in distributed generation systems (DG). This research approaches the control of the SST in a more comprehensive and an organized way. It proposes a compact, versatile and an efficient unified control strategy. This proposal gives rise to three more proposals. i) A method to mitigate the current harmonic distortion which is uniquely software-based and ii) An efficient low-voltage ride-through (LVRT) scheme. Both of those functions come at no extra cost using the proposed unified control scheme. These proposals further demonstrate the proposed strategy’s ability to accommodate further features and modifications. A further contribution to this research addresses the unbalanced load conditions. It proposes a simple, cost-free modification to a resonant filter - making it suitable for the proposed control strategy thus maintaining its simplicity without compromising its practicality. All the proposals of this research have been validated through simulation in Simulink

Design of Passive High Pass Filter for Hybrid Active Power Filter Applications

In recent years there has been considerable concern over power quality, at both distribution and consumer levels, and the need to control reactive power and voltage stability at transmission levels. Active filtering of electric power has now become a mature technology for harmonic and reactive power compensation in two-wire (single phase), three-wire (three phase without neutral), and four-wire (three phase with neutral) ac power networks with nonlinear loads. Active power filter and passive filters (APF & PF) are the traditional ways of compensating for harmonics. However, both of the two ways have some disadvantages, namely resonance and tuning problems in passive filters, and capacity, initial and running cost in APF. Hybrid Active Power Filter (HAPF) has been proposed to overcome the disadvantages of APF and PF. It is a combined system of PF and APF. Appropriate choice of PF and detailed design method for the same is being presented in this thesis, which when combined with APF will eliminate the higher order harmonics. A simple mathematical design procedure is derived for the passive high pass filter. In this thesis, power quality improvement based on HAPF is analyzed for a nonlinear RL-load connected to a 1-phase ac supply which can simultaneously improve the power quality and control the reactive power requirement of the load. The switching algorithm for the APF is presented. The design procedure is limited to the design of passive HPF. However using the designed PF along with existing system consisting of APF is improving the power quality. The obtained results of the proposed HAPF is compared with the existing system with only APF in terms of source current and source voltage spectrums, active & reactive power flow from the filter side to the power system at the point of common coupling (PCC). The studied system is modeled and simulated in the MATLAB/Simulink environment. The performance indices included are THD analysis of source voltage, source current

Ancillary Services in Hybrid AC/DC Low Voltage Distribution Networks

In the last decade, distribution systems are experiencing a drastic transformation with the advent of new technologies. In fact, distribution networks are no longer passive systems, considering the current integration rates of new agents such as distributed generation, electrical vehicles and energy storage, which are greatly influencing the way these systems are operated. In addition, the intrinsic DC nature of these components, interfaced to the AC system through power electronics converters, is unlocking the possibility for new distribution topologies based on AC/DC networks. This paper analyzes the evolution of AC distribution systems, the advantages of AC/DC hybrid arrangements and the active role that the new distributed agents may play in the upcoming decarbonized paradigm by providing different ancillary services.Ministerio de Economía y Competitividad ENE2017-84813-RUnión Europea (Programa Horizonte 2020) 76409

Economic assessment of a public DC charging station for electric vehicles with load shift capability

This paper presents a new concept of public DC fast charging station for Electric Vehicles (EVs) with load shift capability and simplified interface with renewable energy sources. The key element of the proposed charging system consists in an Energy Storage System (ESS) composed by reused electrochemical batteries from EVs. In the proposed system the energy storage capability is used to smooth the intermittent power demand of fast charging systems for EV batteries, present in public charging stations, and also contributes to the stability of the electrical power grid. When integrated in a Smart Grid, the proposed system may even return some of the energy stored in the EVs batteries back to the power grid, always when it is necessary, in order to improve the power grid operation. In addition to these technical advantages, the proposed topology also presents some interesting economic benefits that are analyzed along the paper.FCT – Fundação para a Ciência e Tecnologiainfo:eu-repo/semantics/publishedVersio

Minimizing harmonic distortion impact cause by CS using meta heuristic technique

Non-linear load in the distribution system has caused negative impact to its power quality especially on harmonic distortion. Charging Station (CS) is a non-linear load that widely promoted with the aim to support the continuous usage of Electric Vehicle (EV). This research is focusing on optimal placement and sizing of multiple passive filter to mitigate harmonic distortion due to CS usage at distribution system. There are 6 units of CS which being placed in low voltage buses which indirectly will inject harmonic to the system during charging. Power system harmonic flow, passive filter, CS, battery and the analysis will be model in MATLAB. Multi-objective function which are weight summation approach (WSA) and Pareto Front are used to assist meta heuristic technique which is Modified Lightning Search Algorithm (MLSA) to identify optimum location and sizing of passive filter based on improvement on propose five parameters. From the result, the optimal placements and sizing of passive filter able to reduce the maximum Total Harmonic Distortion (THD) for voltage, current and apparent losses respectively. Therefore, the propose method is suitable to reduce harmonic distortion as well as apparent losses at distribution system with present of CS