Analysis Of Electrical Systems Research Articles

Electrical System of URSM Science and Technology Building: An Analysis

The main goal of this research was to evaluate if the existing power supply, which is three-phase, four-wire, and 400 volts, was safe and cost-effective. The study also intends to perform an Electrical System Analysis of the existing 400V, 3-phase, 4-wire power supply, including short circuit calculations, protective device coordination and protection, and arc-flash analysis. This research is based on the Philippine Standard of Electrical Design as it is applied and used by electrical professionals in the Philippines. Electrical System Analysis calculations are based on the National Electrical Code, IEEE Standards, and the most recent edition of the Philippine Electrical Code (PEC 2017). According to the findings, the URSM Science and Technology Building's current power supply is adequate and ready for future expansion. It was also cost-effective, as they discovered that the URSM's old ISR Building needed to be upgraded. The Short Circuit Analysis reveals that the installed protective devices' KAIC ratings are underrated and should be upgraded. The protective device coordination and protection reveals that the protective equipment must have a 0.2 to 1 second time setting. The required PPE for the building's electrical maintenance staff is shown in the arc flash analysis. This study's overall implications provide necessary inputs and corrective measures for the safety of URSM faculty, students, and other stakeholders.

Integration of PMSG-Based Wind Turbine into Electric Power Distribution System Load Flow Analysis

In this paper, a simple method for modeling and integrating PMSG (Permanent Magnet Synchronous Generator)-based WPP (Wind Power Plant) for load flow analysis of electric power distribution systems is proposed. The proposed model is derived based on: (i) the PMSG torque current equations, (ii) the relationships between PMSG voltages/currents in q-axis and d-axis, and (iii) the equations of WPP powers (namely: turbine mechanical power input, WPP power loss and power output). Application of the proposed model in representative electric power distribution system is also investigated and presented in this paper. The results of the investigation confirm the proposed model validity. The confirmation can also be verified by observing the load flow analysis results where, for each value of turbine power, the substation power output plus the WPP power output is always equal to the total system load plus total line loss (the line loss has been calculated based on the impedances and currents of the distribution lines).

Stability Boundary Analysis of Islanded Droop-Based Microgrids Using an Autonomous Shooting Method

This paper presents a stability analysis for droop-based islanded AC microgrids via an autonomous shooting method based on bifurcation theory. Shooting methods have been used for the periodic steady-state analysis of electrical systems with harmonic or unbalanced components with a fixed fundamental frequency; however, these methods cannot be directly used for the analysis of microgrids because, due to the their nature, the microgrids frequency has small variations depending on their operative point. In this way, a new system transformation is introduced in this work to change the droop-controlled microgrid mathematical model from an non-autonomous system into an autonomous system. By removing the explicit time dependency, the steady-state solution can be obtained with a shooting methods and the stability of the system calculated. Three case studies are presented, where unbalances and nonlinearities are included, for stability analysis based on bifurcation analysis; the bifurcations indicate qualitative changes in the dynamics of the system, thus delimiting the operating zones of nonlinear systems, which is important for practical designs. The model transformation is validated through time-domain simulation comparisons, and it is demonstrated through the bifurcation analysis that the instability of the microgrid is caused by supercritical Neimark–Sacker bifurcations, and the dynamical system phase portraits are presented.

Uncertainty propagation in flight performance of multirotor with parametric and model uncertainties

This paper focuses on the uncertainty propagation in the flight performance of multirotor-type unmanned aerial vehicles from the systematic perspective in conceptual design phase. The multirotor performance is estimated by a conceptual design and analysis framework which is capable of predicting the performance for given mission profiles and multirotor specifications. In this study, not only are parametric uncertainties considered in multirotor components such as rotor, motor and battery, but also model uncertainties in aerodynamics and electric propulsion system analysis models of the framework are taken into account. The model uncertainties in the analysis methods are considered by adopting model uncertainty parameters calculated from experimental data, which is particularly important in conceptual design phase where mathematical methods have relatively lower accuracy. The performance variance under various flight conditions with different multirotor configurations is quantified using Monte Carlo Simulation with 10,000 samples determined by Latin Hypercube Sampling. It is found that the uncertainties in the electric components and circuit analysis are far more dominant than those related with the rotor aerodynamics. Also, the uncertainty effect is nearly independent of the multirotor configuration, yielding similar results in the quadrotor and hexarotor configuration.

A Multi-Frequency DQ Impedance Measurement Algorithm for Single-Phase Vehicle-Grid System in Electrified Railways

Dq impedance measurement is of great importance as a part of the impedance-based analysis. At present, impedance of objects in single-phase vehicle-grid system are mainly obtained by injecting the voltage or current disturbance of one single frequency into the system circularly. However, as the number of measurement frequency points increases, there will produce much time-consuming of measurement. In this paper, a quick dq impedance measurement algorithm for single-phase vehicle-grid system based on multi-frequency sweep is proposed. First, pseudo-random binary sequences (PRBS) and ternary sequences are modified as the driving signals rather than directly injecting into the control link. Then three types of disturbance with specific frequency characteristics are introduced into the system and their parameters setting principle are given for the first time. According to the different characteristics of measurement objects, the proposed algorithms are also different to ensure the maximum specificity and sensitivity. Finally, for different objects in vehicle-grid system like traction network, single-phase converter and dual-interleaved converter, simulation and experimental results based on the hardware in the loop real-time simulation platform both show the correctness of the proposed algorithm, and the possible causes of errors are also analyzed in detail. Moreover, the proposed algorithm makes it possible to quickly measure the dq impedance of the single-phase vehicle-grid system, and the correctness of the theoretical and measured value can be judged and used for the stability analysis of electrical systems.

Voltage Profile Enhancement and Power Loss Reduction with Economic Feasibility Using Small Capacity Distribution Transformers

Usually, rural areas can be electrified via three-phase distribution transformers with relatively large capacities. In such areas, low voltage lines are used for long distances, which cause power losses and voltage drop for different types of consumers. Reducing losses and improving voltage profiles in rural distribution networks are significant challenges for electricity distribution companies. However different solutions were proposed in the literature to overcome these challenges, most of them face difficulties when applied in the conventional distribution network. To address the above issues, an applicable solution is proposed in this paper by installing a number of small-capacity distribution transformers instead of every single large-capacity transformer in rural areas. The proposed approach is implemented in the branch network of Al-Hoqool village, which belongs to the Nineveh distribution network. The network has been inspected on-site, drawn, and analyzed using the electrical systems analysis program (ETAP). The analysis showed that using the single-phase pole-mounted transformers can improve the voltage in the network’s end by 29% and enhance the voltage profile for all consumers. The analysis has also demonstrated that the modification can reduce the total power losses by 78% compared to the existing network. Concerning the economic aspect, the payback period for the proposed network is assigned to be 20 months.

Electrothermal Model of Coupled Inductors with Nanocrystalline Cores

The paper proposes a new electrothermal model of a coupled inductor containing a nanocrystalline core dedicated to the analysis of electrical energy conversion systems. The formulated model has a form of a subcircuit for SPICE. The model takes into account the influence of direct current, frequency, skin effect, temperature, self-heating, and mutual thermal couplings on the parameters and characteristics of the coupled inductors. The form of the developed model and the method of model parameter estimation are presented. The applied measuring system is presented. The results of measurements and calculations made with the use of the proposed model are presented and commented on.

Power jacking your station: In-depth security analysis of electric vehicle charging station management systems

The demand for Electric Vehicles (EVs) has been exponentially increasing, and to achieve sustainable growth, the industry dictated rapid development of the supporting infrastructure. This requires building a reliable EV charging ecosystem that serves customer demands while ensuring the security of the Internet-enabled systems and the connected critical infrastructure against possible cyber attacks. To this end, we devise a system lookup and collection approach to obtain a representative sample of widely deployed EV Charging Station Management Systems (EVCSMS). Furthermore, we leverage reverse engineering and penetration testing techniques to perform a first-of-a-kind comprehensive security and vulnerability analysis of the identified EVCSMS and their software/firmware implementations. Indeed, our systematic analysis unveils an array of vulnerabilities, which demonstrate the insecurity of the EVCSMS against remote cyber attacks. Considering the feasibility of such attacks, we discuss attack implications against the EV charging stations (EVCS) and their users. More importantly, we simulate the impact of practical cyber attack scenarios against the power grid, which result in possible service disruption and failure in the grid. Finally, while we recommend mitigation measures, our discoveries raise concerns about the lack of adequate security considerations in the design of the deployed EVCS, which will motivate vendors to take immediate action to patch their developed systems. Indeed, our communication with the concerned parties resulted in positive responses from some vendors such as Schneider Electric, who acknowledged our findings by reserving 12 CVEs, respectively.

Comparative analysis of battery electric vehicle thermal management systems under long-range drive cycles

Due to increasing regulation on emissions and shifting consumer preferences, the wide adoption of battery electric vehicles (BEV) hinges on research and development of technologies that can extend system range. This can be accomplished either by increasing the battery size or via more efficient operation of the electrical and thermal systems. This study endeavours to accomplish the latter through comparative investigation of BEV integrated thermal management system (ITMS) performance across a range of ambient conditions (-20 °C to 40 °C), cabin setpoints (18 °C to 24 °C), and six different ITMS architectures. A dynamic ITMS modelling framework for a long-range electric vehicle is established with comprehensive sub models for the operation of the drive train, power electronics, battery, vapor compression cycle components, and cabin conditioning in a comprehensive transient thermal system modelling environment. A baseline thermal management system is studied using this modelling framework, as well as four common thermal management systems found in literature. This study is novel for its combination of comprehensive BEV characterization, broad parametric analysis, and the long range BEV that is studied. Additionally, a novel low-temperature waste heat recovery (LT WHR) system is proposed and has shown achieve up to a 15% range increase at low temperatures compared to the baseline system, through the reduction of the necessary cabin ventilation loading. While this system shows performance improvements, the regular WHR system offers the greatest benefit, a 13.5% increase in cold climate range, for long-range BEV drive cycles in terms of system range and transient response without the need for additional thermal system equipment.

Design optimisation and cost analysis of linear vernier electric machine-based gravity energy storage systems

Energy storage technologies have been gaining increasing attention as a way to help integrate variable and intermittent renewable energy sources into the grid. In this paper, a novel gravity energy storage system which features a linear electric machine-based hoisting mechanism is investigated. The storage system utilises the inherent ropeless operation of linear electric machines to vertically move multiple solid masses to store and discharge energy. The consequent-pole linear Vernier hybrid machine is chosen as the machine topology, and a multi-objective design optimisation is conducted. The optimisation results are then used to perform a cost analysis by means of a levelised cost of storage calculation. A sensitivity analysis is also done to investigate some of the assumptions made in the levelised cost of storage calculation that have no direct influence on the design of the linear electric machine. This study shows that the proposed storage system has a cost-competitive advantage when used in applications with high power and a high number of annual cycles. The paper also highlights the most important factors that affect the economic performance, clearly indicating where further improvements can be made to further increase the viability of the storage system.

Pressure Retarded Osmosis Power Units Modelling for Power Flow Analysis of Electric Distribution Networks

Pressure retarded osmosis (PRO) power units, which produce electrical energy from salinity gradient sources located at coastlines, are a technology still in the process of maturation; however, there is an expectation that this technology will need to be integrated into electrical distribution networks. Such integration will drive changes in the electric response of the distribution systems which may lead to harmful operating conditions. Power flow analysis is a tool used to reveal the steady-state operating condition of distribution systems and which could be extended to study and address the integration of PRO power units. To the best of the authors’ knowledge, such extension of power flow analysis has not yet been addressed in the literature. Accordingly, this paper comprehensively provides a model to evaluate the electric current and complex power produced by PRO power units. This model is directly embedded in the forward-backward sweep (FBS) method, extending the power flow analysis of electric distribution systems in this way so as to consider the integration of PRO power units. The resulting approach permits revealing of the steady-state operating response of distribution systems and the effects that may be driven by the integration of PRO power units, as corroborated through numerical results on a 14-node test distribution system.

Novel stability and passivity analysis for three types of nonlinear LRC circuits

In this paper, the global asymptotic stability and strict passivity of three types of nonlinear RLC circuits are investigated by utilizing the Lyapunov direct method. The stability conditions are obtained by constructing appropriate Lyapunov function, which demonstrates the practical application of the Lyapunov theory with a clear perspective. The meaning of Lyapunov functions is not clear by many specialists whose studies based on Lyapunov theory. They construct Lyapunov functions by using some properties of Lyapunov functions with much trial and errors or for a system choose candidate Lyapunov functions. So, for a given system Lyapunov function is not unique. But we insist that Lyapunov (energy) function is unique for a given physical system. In this study we highly simplified Lyapunov’s direct method with suitable tools. Our approach constructing energy function based on power-energy relationship that also enable us to take the derivative of integration of energy function. These aspects have not been addressed in the literature. This paper is an attempt towards filling this gap. The results are provided within and are of central importance for the analysis of nonlinear electrical, mechanical, and neural systems which based on the system energy perspective. The simulation results given from Matlab successfully verifies the theoretical predictions.

Reliability Centred Planning, Mapping & Analysis of Electronics and Electrical Systems in Electric Mobility

Reliability of a product is very critical aspect for a new product to create a success story in present age. This paper is focused on automobile industry especially in electric mobility domain. IC engines are in this market from last 100+ years and too much improvement work has been done in IC engine domain. First car powered by IC engine was made in 1885 by Karl Benzand from 1885 to present the IC engine mobility have undergone numerous process improvements and established them as a reliable mode of mobility. There are many process models available online which can be used to improve the reliability of IC engine powered mobility. In case of electric mobility there is major integration of three different domains electrical, mechanical & electronics. Electrical mobility is just 2 decade old and major developments happened in this space in last one decade. The major challenge in electric mobility domain is the change content, in IC engine mobility the if we compare one car model to another car model the change content is <25% but in case of electric mobility vs IC engine mobility the change content is >75%. Now the challenge is to manage & effectively synchronize this high change content moreover to establish the product reliability as equal or better than existing IC engine powered mobility. There are various reliability improvement models are available in electrical, mechanical and electronics domain. There is a need to integrate the reliability improvement models of electrical and electronics domain with automobile (mechanical domain) keeping automobile reliability improvement models as masters of process so that to establish product reliability in electric mobility. The overall aim of this dissertation work is to develop a reliability engineering model to establish the reliability and dependability of electric mobility in future.

A mho type phase comparator relay guideline using phase comparison technique for a power system

This paper presents a mho distance relay simulation based on the phase comparison technique using a typical electrical power systems analysis software for two cases: when the operation state is close to the static voltage limit and during a dynamic perturbation in the system. The paper evaluates the impedance variations caused by complex voltage values, the mho polarization, and the comparator operating region into the complex plane. In addition, the paper found the information for the dynamic perturbations from the outputs considering a mid-term stability program. The simulation of the mho-phase comparator in the static voltage proximity limit detects unit distance elements with impedance measured close to reach the threshold in the steady-state. Dynamic mho simulations in the complex plane are successfully tested by plotting time phase difference curves on the comparator input signals. Relay programmers can use these curves to analyze other phase comparators applications and the corresponding models in the complex plane.

An Analytical Model for Small Signal Stability Analysis in Unbalanced Electrical Power Systems

This paper presents a general model to carry out a small signal stability analysis in electrical power systems (EPSs) that operate in unbalanced conditions. The classic traditional approach is based on a phase representation where it is supposed that the triphasic electric grid does not suffer any variations during its operation. With the presence of unbalances in transmission lines and loads, it is necessary to develop a general model that allows answering the needs and challenges with which modern electric systems must deal. The present work firstly intends to address the three-phase representation of an EPS, including the controllers. The proposed model is applied to a classical test system, a three machine-nine bus system, considering all the dynamic and algebraic variations associated with angular stability analysis. The proposed approach to small signal stability analysis shows results that differ from the classical analysis. The results are backed up with time domain simulations, and therefore, these results could be used in the calculation of the controllers that operate in unbalanced multimachine systems.

Performance analysis of electrical systems of vehicles under the external electromagnetic exposure

The study results of malfunctions of electrical systems of modern vehicles due to external electromagnetic exposure are presented in the paper.

Assessment on the Behavior of Harmonic Phase Angles

Existing methodologies and protocols for characterizing the harmonic components of voltage and current from digital measurements only consider the measurement of the amplitudes of these quantities. Thus, the phase angles of the harmonic components, required for some types of analysis in electrical systems, are simply ignored. In fact, there is no standardized methodology for measuring and temporal aggregation of phase angles of harmonic components. In this context, the present article aims to contribute to the subject by presenting the behavior of the phase angles of the harmonic components over time under different conditions. For this purpose, specific voltage and current waveform measurements were performed to analyze the phase angle behavior of the harmonic components over 24 hours, considering individual electrical loads, as well as residential and commercial installations, both connected to a low voltage power distribution system. Additionally, the behavior of the phase angles of the harmonic components measured at the output of a medium voltage distribution feeder will be presented. The results show a sporadic behavior for these quantities, reinforcing the need to develop a new methodology for temporal aggregation of phase angles of harmonic components.

The Broken Symmetry of Output Currents in a Matrix Converter and Its Recovery Control

Symmetry is not only used to simplify the analysis of three-phase electrical systems, but it is also used to define its voltages, currents and loads. When the loads are symmetrical, the currents of a three-phase AC system are expected to be symmetrical as well. Given the proper conditions, in converters such as the matrix converter (MC), the output voltages and currents are expected to be sinusoidal with periodic symmetry. However, in some cases this symmetry is broken so that, there appears nonlinear behaviors such as quasiperiodicity and so on. Based on simulations and experiments, this paper focuses on an analysis of a quasiperiodic behavior and the presence of a DC component in the output currents of a Venturini modulated MC. The presence of such behaviors in the output currents indicates that the symmetry in a period is broken. The broken symmetries appear when the input and output frequencies are mismatched. In addition, this paper shows the possibility to recover the symmetry of the output currents of the MC. The method for symmetry recovery is based on a time-delayed feedback control. The simulation and experimental results indicate the possibility of attenuating the quasiperiodic behavior and DC component.

Localización óptima de plantas virtuales de generación en sistemas eléctricos de potencia basados en flujos óptimos de potencia

El presente trabajo determina la ubicación óptima de plantas virtuales de generación analizando el comportamiento en estado estacionario del sistema, la planta virtual de generación combina una amplia variedad de recursos energéticos distribuidos y los opera como un sistema unificado. Se identificará la localización óptima de plantas virtuales de generación para mejorar el perfil de tensión nodal del sistema de potencia basado en flujos óptimos de potencia de corriente directa con restricciones económicas. El análisis de sistema eléctrico se realiza mediante flujos óptimos de potencia de corriente continua basado en programación lineal entera mixta respetando restricciones económicas, ambientales, cargabilidad de las líneas de transmisión, el manejo de las demandas, nivel de sobrecarga, desviación angular y perfil de tensión. Se realiza una revisión literaria plantas virtuales de generación la cual tiene una serie de ventajas competitivas como el uso de tecnologías renovables y de alta eficiencia energética. También dispone de información para el desarrollo del flujo óptimo de corriente continua.

Interpreting Frame Transformations in AC Systems as Diagonalization of Harmonic Transfer Functions

Analysis of ac electrical systems can be performed via frame transformations in the time-domain or via harmonic transfer functions (HTFs) in the frequency-domain. The two approaches each have unique advantages but are hard to reconcile because the coupling effect in the frequency-domain leads to infinite dimensional HTF matrices that need to be truncated. This paper explores the relation between the two representations and shows that applying a similarity transformation to an HTF matrix creates a direct equivalence to a frame transformation on the input-output signals. Under certain conditions, such similarity transformations have a diagonalizing effect which, essentially, reduces the HTF matrix order from infinity to two or one, making the matrix tractable mathematically without truncation or approximation. This theory is applied to a droop-controlled voltage source inverter as an illustrative example. A stability criterion is derived in the frequency-domain which agrees with the conventional state-space model but offers greater insights into the mechanism of instability in terms of the negative damping (non-passivity) under droop control. The paper not only establishes a unified view in theory but also offers an effective practical tool for stability assessment.