Arash Anzalchi

A survey on security assessment of metering infrastructure in Smart Grid systems

Effective integration of renewable energy resources, energy management and better usage of the high voltage transmission system are major motivating forces for an improved electric grid regularly called the Smart Grid. Along with the soundless features of the Smart Grid, cyber security appears to be a serious issue because many electronic devices are connected via communication networks throughout critical power services, which has a direct impact on the reliability of such a common infrastructure. An assessment of cyber security topics in the Smart Grid is presented in this paper especially, security necessities of AMI, network vulnerabilities, attack countermeasures, secure communication protocols and architectures in the Smart Grid. Cyber-attacks against the power grid may aim to disrupt operations modifying or inserting messages. For example, malicious entities might change the set points at outstation devices, by pretending to be a master device at a control center, and cause instability in the grid. Satisfactory protection contains authenticating both the devices and control commands.

Artificial neural network based Duty Cycle estimation for maximum Power Point tracking in Photovoltaic systems

According to a nonlinear current-voltage characteristic of Photovoltaics (PV) we need to track maximum power output of PV generation units instantly. The aim of this paper is to introduce a non-complicated method for tracking the maximum Power Point without any previous knowledge of the physical parameters linked with a Grid-Connected photovoltaic (PV) system using artificial neural networks (ANN) modelling. The ANN is trained in various conditions of PV Output Voltage and PV Output Current to forecast the Duty Cycle of DC-DC boost converter as the MPPT device. The proposed technique is implemented in Matlab/Simulink and compared with the conventional method of incremental conductance. Simulation results show a good performance of the ANN based MPPT controller. MPPT techniques that properly detect the global MPP has been widely investigated in the literature. They include hill climbing (HC), incremental conductance (IncCond), perturb-and-observe (P&O), and fuzzy logic controller (FLC). As the best of our knowledge estimation of the duty cycle of the DC-DC boost converter by Artificial Neural Network and using it in place of the whole MPPT controller and using Voltage and current has not been done so far in the literature.

A New Topology of Higher Order Power Filter for Single-Phase Grid-Tied Voltage-Source Inverters

In order to reduce the influence of the grid harmonic currents and voltages, harmonic compensation is regularly implemented for a grid-tied inverter. In this study, a new topology of a higher order power filter for single-phase grid-tied voltage-source inverters, named L(LCL)2, is presented. The subscript is added to the name to prevent confusion with the LLCL filter. In the proposed design, the inverter side inductance is divided into three parts, and the grid side inductor is removed. Also, an additional resonant branch at the double of the switching frequency is added to the traditional LLCL filter to attenuate high-frequency harmonics. The overall inductance of the recommended filter is smaller than the LLCL filter. A comparative study and discussions on the subject of the traditional LLCL filter and the proposed L(LCL)2 filter have been conducted and assessed through an experimental hardware implementation on a 700 W, 120 V/60 Hz single-phase grid-tied inverter. Furthermore, a straightforward engineering design benchmark is suggested to discover parameters of the L(LCL)2 filter. Moreover, stability analysis, loss analysis and an optimization of the L(LCL)2 filter parameters have been conducted in this study. The analysis shows that in comparison with the LLCL filter, the L(LCL)2 filter not only has lower voltage drop and less total inductor size, but also has improved performance in decreasing high-order current harmonics.

Single-Stage Three-Phase AC–AC Matrix Converter for Inductive Power Transfer Systems

A direct three-phase ac-ac matrix converter for inductive power transfer (IPT) systems with soft-switching operation is introduced. The proposed topology is expected to have a high reliability and extended lifetime due to the soft-switching operation and elimination of short-life electrolytic capacitors. The soft-switching operation will also reduce switching stress, switching loss, and electromagnetic interference of the converter. A variable-frequency control strategy based on the energy-injection and free-oscillation technique is used to regulate the resonant current, the resonant voltage, and the output power. With the use of reverse-blocking switches, the proposed converter can be built with a reduced number of switches (only seven), which will consequently increase the reliability and efficiency and reduce the cost of the converter. The converter operates in eight modes, which are described in detail. With the use of the proposed converter as the primary converter, simulation analysis and experimental implementations on a case study IPT system show that the current regulation control method can fully regulate the output current and output power around user-defined reference values, thus making it suitable for dynamic IPT applications, where the system has inherent variations.

Analysis of Carbon Tax as an Incentive Toward Building Sustainable Grid with Renewable Energy Utilization

This study presents an analysis of technical and financial viability of hybrid grid/Renewable Energy System (RES) configurations for a neighborhood in Miami. Assessment criteria comprised reduction in net present cost (NPC), cost of energy (COE) and greenhouse gases (GHG). Mat lab® Simulink and the RES software HOMER were utilized as the assessment tool. The modeling is performed based on hourly load data of Miami, south east coast of the USA. Grid connection is required to provide the energy backup and as well to commercialize the system. This research analyses cost efficacy to encourage use of renewable energies, specifically, wind and solar. For this purpose, an evaluation of the Co2 tax level of cost effectiveness of the system is also conducted. Outcomes demonstrate that there is remarkable potential of Co2 mitigation along with COE reduction and sustainable and resilient energy development from employing RES. The results show that there are enough prospects for renewable based DG generation in existence of appropriate policy allocation for GHG emission penalties and Market Price Referent (MPR). Thither is a considerable quantity of literature available on renewable incentives. The focus of the experimental studies is mostly on the comparison of the different supporting action plans and in their advantage to promote the utilization of renewable technologies but not on their cost to reduce Co2 emissions.

A combinatorial approach for addressing intermittency and providing inertial response in a grid-connected photovoltaic system

The operation of a photovoltaic (PV) generating system under intermittent solar radiation is a challenging task. Furthermore, with high penetration levels of photovoltaic energy sources being integrated into the current electric power grid, the performance of the conventional synchronous generators is being changed and grid inertial response is deteriorating. This paper proposes a combined virtual inertia emulator (VIE) and a hybrid battery-supercapacitor-based energy storage system for enhancing the stability of the Microgrids and smoothing the short-term power fluctuations simultaneously. Not only could the suggested system overcome the slow response of battery system (including dynamics of battery, controller, and converter operation) by redirecting the power surges to the supercapacitor system, but also enhance the inertial response by emulating the kinetic inertia of synchronous generator. Control systems for the VIE and battery-supercapacitor storage system are presented in this paper. Correspondingly simulation results are discussed to validate the effectiveness of the proposed scheme. In this paper, Matlab Simulink software has been considered to develop control designs of VIE and Hybrid Energy Storage System (HESS). Through these studies, it will be demonstrated that the recommended method is capable of achieving voltage and frequency regulation and effective management of the hybrid storage system. Since the suggested technique focuses on short-term fluctuations and includes no long-term power regulation, it needs no mass storage device. Thus, the method is economical. The other concerns raised by renewables (e.g., forecast accuracy, low voltage ride-through, etc.) have not been addressed within this study.

Finite element based design optimization of magnetic structures for roadway inductive power transfer systems

Design optimization of magnetic structures for roadway inductive power transfer (IPT) systems based on 2D finite element analysis (FEA) is proposed. The proposed method can be used to find the optimal structure for IPT systems based on prioritization of different objectives such as efficiency, cost, etc. A Multi-objective genetic algorithm (MOGA) coupled with 2D FEA is used for the co-optimization of primary and secondary magnetic structures. Also, Electromagnetic field (EMF) emissions of the pads are considered to meet human exposure regulations in compliance with standards as defined by International Commission on Non-Ionizing Radiation Protection (ICNIRP). A 1 kW roadway IPT system is investigated as the case study and the results of the optimization are presented using different objective functions.

Pareto optimization of circular power pads for contactless electric vehicle battery charger

Design optimization of circular power pads for inductive power transfer (IPT) systems with applications in electric vehicle battery charger is proposed. A multi-objective optimization coupled with 2D finite element analysis (FEA) is used to find the Pareto-optimal solutions for circular magnetic structures considering different objective functions, such as power transfer efficiency, material cost, and horizontal misalignment tolerance of the IPT system. 2D FEA is used to calculate self and mutual inductances between primary and secondary pads, ohmic loss in coils, core loss in ferrites, stray loss in aluminum shields and electromagnetic field (EMF) emissions of the system. Practical limitations of the power electronic converters such as frequency, VA rating, operating quality factor, and EMF emissions are all considered in the proposed optimization. A 10 kW electric vehicle battery charger IPT system with circular power pads is investigated as the case study and Pareto-optimal solutions for this system are presented. Experimental test results on one of the Pareto-optimal solutions are in good agreement with the calculations using the proposed method. The proposed design optimization method provides a tool for finding highly efficient, flexible and cost-effective solutions for contactless electric vehicle battery charger.

A modified higher order power filter for grid-connected renewable energy systems

In order to reduce the influence of the grid harmonic currents and voltages, harmonic compensation is regularly implemented for a grid-tied inverter. In this paper a new topology of higher order power filter for single-phase grid-tied voltage-source inverters (VSI), named L(LCL)2, is introduced. The subscript is added to the name to avoid confusion with LLCL filter. In the proposed design the inverter side inductance is divided into three parts, and the grid side inductor is removed. Also an additional resonant branch at the double of switching frequency is added to the traditional LLCL filter to attenuate high frequency harmonics. The total inductance of this filter is less than LLCL filter with the amount of the grid side inductor. A comparative study and discussions on the subject of the traditional LLCL filter and the proposed L(LCL)2 filter have been conducted and assessed through both experimental hardware implementation and Matlab/Simulink-based simulation on a 700 W, 120V / 60 Hz single-phase grid-tied inverter. Also, a straightforward engineering design benchmark is suggested to discover parameters of the proposed L(LCL)2 filter. It is concluded that, compared with the LLCL filter, the L(LCL)2 filter not only has less voltage drop and total inductor size, but also has better performance on reducing high order current harmonics.

Power quality and voltage profile analyses of high penetration grid-tied photovoltaics: A case study

Installed Photovoltaic (PV) capacity across the smart distribution grid has been on the rise in order to reduce greenhouse gas emissions. However, under high penetration of PV, there could be potential impacts on the operation and planning of distribution networks. In order to evaluate the impacts of grid-tied PV, a case study on power quality and voltage profile analyses is conducted using a 1.1 MW AC grid-tied PV power plant located at Florida International University. As part of the power quality analysis, study explores Total Harmonic Distortion (THD) and high power and high energy ramp rate analysis. Current THD is posed to trigger problems when generation is highly intermittent wherein Voltage THD does not have a tight relationship with power output. For voltage profile analysis, the case study considers peak and minimum daytime load scenarios under different levels of penetration, including the existing level, and appraises the plants current and potential impacts in steady-state and time-series scenarios. The effect of using smart inverters with grid-support functions is also simulated. Results show that some major problems like voltage deviations and feeder losses can be expected at 60% PV penetration in minimum daytime load. The number of switching operations for voltage regulators also increase when smart inverters operate at Volt/VAr control mode. Results of the case study are discussed to highlight the significance of these issues in high penetration scenarios.