Electrical Interconnection System Research Articles

Study of the location for the installation of a photovoltaic plant for the generation of electric power in Puerto Rico

The description of the geographical location study of a photovoltaic plant to be constructed in the coming years in Puerto Rico is presented as part of a major project the island has embarked upon to enhance its electrical service. This study entailed selecting the terrain based on its topography, as well as assessing the convenience of its location concerning its proximity to the national electrical interconnection system. Additionally, relevant consultations were conducted regarding the rights over the lands that will be affected by the construction of the photovoltaic plant (easements). As a result of this study, a plot of land spanning 131.56 hectares in the Juana Díaz sector, 1.59 kilometers from the electrical interconnected system, was identified as a suitable location, impacting only five easements.

Safety risk assessment of aircraft EWIS based on the improved combined weight and cloud model

Purpose This study aims to conduct the aircraft electrical wiring interconnection system (EWIS) safety risk assessment process abundantly and hierarchically and establish the assessment index system considering the weights and interrelationships of different levels of indices. Design/methodology/approach Due to the failure of EWIS being multifactorial, hidden and diverse, this paper divides the factors influencing the failure of EWIS into 3 primary indices, 13 secondary indices and 38 tertiary indices. Taking open circuit failure (OCF) and short circuit failure (SCF) as examples, calculate the weights of assessment indices based on the triangular fuzzy number analytic hierarchy process (TFNAHP) and triangular fuzzy number decision-making trial and evaluation laboratory (TFNDEMATEL). The cloud model (CM) divides the risk levels and obtains the safety risk assessment results. The comparative analyses of different weight calculation methods, different failure modes and different aircraft EWIS zones verify the effectiveness and practicability of the proposed method. Findings The results show that the proposed method aligns more with the actual situation than other methods. Also, the results identify key focus objects in EWIS safety risk assessment, such as the surrounding environmental factors among the primary indices having the most significant influence on OCF and SCF, the risk level of SCF being higher than that of OCF, etc. Originality/value This paper proposes a safety risk assessment index system for aircraft EWIS based on the cable parameters, surrounding environmental factors, installation and protection methods. The weight assignment is added to the assessment index system, and the safety risk assessment model is constructed by combining TFNAHP, TFNDEMATEL and CM.

Low-Pressure Optical Detection, Location, and Quantification of Electrical Discharges in Aircraft Wiring Systems

Strict regulations issued by international administrative bodies limit the CO2 equivalent emissions for new aircraft, while increasing efficiency requirements. To reach this goal, next generations of aircraft will use more electrical power than their predecessors, so distribution voltage levels will inevitably increase to limit the weight of the electrical wiring interconnect system (EWIS). However, such increased voltage levels generate higher electric stresses in insulation materials as well as in electric and electronic components; thus new failure modes triggered by electrical discharges will appear, their effects being aggravated by harsh environments typical of aircraft systems. The combined effect of higher electrical stresses, compact designs, and low-pressure operating conditions greatly intensifies the risks of premature insulation failure due to electrical discharge activity. This paper shows that by using image sensors, it is possible to detect, localize, and quantify the intensity of electrical discharges occurring in aircraft environments. Through experiments carried out in a low-pressure chamber using an image sensor, this work detects and determines the intensity of electrical discharges generated in electrical wires in their initial stage, long before major faults develop. This paper also shows that the intensity of the discharges calculated from the digital images obtained with the image sensor is directly proportional to the electrical energy involved in the discharge process and increases linearly with the applied voltage. Due to the difficulty of detecting these failure modes at a very early stage, this strategy could potentially facilitate predictive maintenance tasks while contributing to increased levels of aircraft safety.

Active-reactive power collaborative optimization model of electrical interconnection system based on deep learning under the goal of “carbon neutrality”

With the goal of carbon neutralization put forward, new energy units have gradually become the main power supply, and its volatility has brought great challenges to the control and optimization of the system, especially the distribution network. In order to solve the reactive power problem caused by the high proportion of renewable energy connected to the distribution network, a source network load storage centralized optimal dispatching model considering reactive power optimization and multi energy collaborative interaction is proposed. The model aims at the optimal operation cost, minimum network loss and minimum carbon emission of the multi energy system, and considers reactive power compensation, energy storage regulation and energy conversion, so as to realize the safe and low-carbon economic dispatching of the electrical interconnection system. The switching capacity of the discrete reactive power compensation device is linearized, and the model is transformed into a mixed integer second-order cone programming problem for solution. The simulation results show that the proposed method can effectively compensate the reactive power required by the wind turbine parallel network, coordinate the energy interaction between electricity and gas, and improve the stability and flexibility of the distribution network after large-scale renewable energy access, According to the charging and discharging power and charge state, and the automatic adjustment of the gears of on load voltage regulating transformer and compensation capacitor bank, this paper shows that the system has safe and stable operation performance.

Study on safety design and analysis method for electrical wiring interconnection system

A safety assessment for electrical wiring interconnection system (EWIS) was required, since the 4th revision of CCAR-25. At present, there is no systematic safety assessment method, which affects the airworthiness certification of military and civil aircraft. According to the safety assessment requirements, the requirements of new regulation 25.1709 were interpreted. Combining with the current situation of military and civil aircraft, the safety design and analysis method was established, and the safety verification technology was expanded, which can effectively identify the potential safety hazards of EWIS. Through the development of reasonable and effective mitigation to avoid the occurrence of the potential safety hazards, it can provide support and certification for airworthiness. Taking the thrust reverse system as an example, the safety application method of quantitative and qualitative for EWIS was explored. The results show that the proposed EWIS safety design and analysis method can effectively identify the potential safety hazards, and guide the safety design of EWIS.

Addressing Safety concerns in Hybrid Electric Aircrafts: In-Flight Icing Detection, Moisture Detection in Fuselage and Electrical Wiring and Interconnect System (EWIS)

Moisture - in the form of water or ice – has adverse consequences on the performance of an aircraft including wing stall, tail stall, loss of thrust, engine flameout, and material damage arising from corrosion and electrical shortcuts. During flight, a large flux of supercooled water droplets on the surface of a hybrid electric aircraft per unit time could result into icing. A prototype to detect ice accretion on supercooled aircraft surface using acoustic emissions is developed. Moreover, during descend, a large portion of frost/ice melts rapidly due to rise in temperature. If not controlled, water may seep inside a hybrid electric aircraft body through gaps in joints. Furthermore, for the problem of water ingression in the wiring of hybrid aircrafts, titanium carbonitride-polyvinyl alcohol (TiCN-PVA) composite material is placed in direct water contact to work as grid health monitoring sensor. For the problem of water ingression inside structural parts (floor, bilge, etc.), an electrically conductive epoxy – carbon black composite is fabricated, characterized using SEM, and tested for DC conductivity under dry and wet conditions. Effect of different mixing intensities on morphology of carbon black in epoxy has also been explored. Through literature survey and trial and error, an optimized method at laboratory scale for preparation of carbon black-epoxy composite material has been presented.

An Evaluation Method for Electrical Contact Failure Based on High-Frequency Impedance Model

As a major component of electrical wiring interconnection systems (EWISs), aircraft electrical connectors are used for the transmission of electrical signals and electrical connection between electrical equipments. It is known that electrical contact failure is the primary failure mode of connectors. Contact resistance often presents a transient characteristic that is difficult to reflect the degradation comprehensively. The electrical contact failure mechanism of connectors is studied in this article. In order to evaluate and quantify the electrical contact failure state, a high-frequency contact impedance model is established to represent the relationship between microphysical characteristics and electrical parameters. Furthermore, the influence of surface roughness and corrosion degree on the high-frequency contact impedance model is investigated by finite-element simulation and accelerated degradation experiment. The trends of contact impedance at high frequency are compared with that of contact resistance at dc condition under the circumstances of different degradation degrees. Finally, the variation law of contact impedance at high frequency is revealed, which can provide the theoretical basis for performance degradation assessment, service life prediction, and reliability evaluation for electrical connectors.

Special Issue on Embedded Sensors for Fault Diagnosis in Electrical Wiring Interconnection Systems, Power Grids, Structural Cables, Pipelines, and Electrical Machines

In the era of the Internet of Things (IoT), electrical wiring interconnection systems (EWIS) are massively hosted everywhere in many fields where the transfer of energy and information is a fundamental pillar to guarantee the good performance of a system. In addition, the huge technological and industrial uprising ensured by the emerging fourth Industrial Revolution is forcing electrical machines and instruments toward massive transformations and more complexity than ever before. Accordingly, the health and integrity of any system are essential for the proper operation of any application. Yet, faults and failures are inevitable. They can lead to catastrophic problems on both economical and human levels. Airplane crashes, massive fires, explosions, and so on are examples of such consequences. Accordingly, fault detection, diagnosis, and location have been always substantially important for ensuring safety, security, integrity, and optimal performance for any system. Notably, fault diagnosis of structural cables integrated in dams, bridges, concrete, and so on have also formed a cornerstone in the context of health monitoring of such structures. The same applies for oil and gas pipelines, subsea cables, umbilicals, and so on.

Alpha-SIM: A quick 3D geometry model simplification approach to support aircraft EWIS routing

Routing design of aircraft Electrical Wiring Interconnection System (EWIS) is time-consuming and error-prone. A solution, which automatically routes the EWIS inside the aircraft Digital MockUp (DMU), has been proposed and presented in the previous publications. The DMU, however, includes over-detailed features, which hardly influence the routing results but significantly increase the geometry-involved computational time thus hampering any automated routing. These features cannot be easily and efficiently suppressed. Therefore, a quick 3 D geometry simplification method, named Alpha-SIM, is proposed to enable a quick simplification of the airframe components included in the DMU and improve the benefit of the aforementioned automatic EWIS routing approach. The method is inspired by Descriptive Geometry techniques and the 3 D modelling approach using 2 D sketches, and aims at removing very detailed and/or internal features while preserving the intuitive notional shape of the given CAD model. The intuitive notional shape is represented by a 3 D point cloud of the model outer boundary and their 2 D projections on user-defined planes. These 2 D projections are then processed such to generate a set of 2 D profiles, called Alpha-Shapes, which are used, eventually, to re-build the 3 D model of the DMU components in a simplified/de-featured manner. By controlling the density of the 3 D points and the Alpha value to generate the 2 D profiles from the point projections, various geometric approximation levels can be achieved. The results of the test cases demonstrate the efficiency and effectiveness of the proposed method on the geometry simplification for automatic EWIS routing.

Three-dimensional point cloud analysis for automatic inspection of complex aeronautical mechanical assemblies

We present a robust approach for detecting defects on an aircraft electrical wiring interconnection system in order to comply with the safety regulations such as the forbidden interference and allowed bend radius of cables and/or harness in mechanical assemblies. For this purpose, we exploit 3-D point clouds acquired with a 3-D scanner and the 3-D computer-aided design (CAD) model of the assembly being inspected. Our method mainly consists of two processes: an offline automatic selection of informative viewpoints and an online automatic treatment of the acquired 3-D point cloud from said viewpoints. The viewpoint selection is based on the 3-D CAD model of the assembly and the calculation of a scoring function, which evaluates a set of candidate viewpoints. After the offline viewpoint selection is completed, the robotic inspection system is ready for operation. During the online inspection phase, a 3-D point cloud is analyzed for measuring the bend radius of each cable and its minimum distance to the other elements in the assembly. For this, we developed a 3-D segmentation algorithm to find the cables in the point cloud, by modeling a cable as a collection of cylinders. Using the segmented cable, we carried out a quantitative analysis of the interference and bend radius of each cable. The performance of the inspection system is validated on synthetic and real data, the latter being acquired by our precalibrated robotic system. Our dataset is acquired by scanning different zones of an aircraft engine. The experimental results show that our proposed approach is accurate and promising for industrial applications.

Fault Diagnosis for Electrical Systems and Power Networks: A Review

In this paper, we review the state of the art in the detection, location, and diagnosis of faults in electrical wiring interconnection systems (EWIS) including in the electric power grid and vehicles and machines. Most electrical test methods rely on measurements of either currents and voltages or on high frequency reflections from impedance discontinuities. Of these high frequency test methods, we review phasor, travelling wave and reflectometry methods. The reflectometry methods summarized include time domain reflectometry (TDR), sequence time domain reflectometry (STDR), spread spectrum time domain reflectometry (SSTDR), orthogonal multi-tone reflectometry (OMTDR), noise domain reflectometry (NDR), chaos time domain reflectometry (CTDR), binary time domain reflectometry (BTDR), frequency domain reflectometry (FDR), multicarrier reflectometry (MCR), and time-frequency domain reflectometry (TFDR). All of these reflectometry methods result in complex data sets (reflectometry signatures) that are the result of reflections in the time/frequency/spatial domains. Automated analysis techniques are needed to detect, locate, and diagnose the fault including genetic algorithm (GA), neural networks (NN), particle swarm optimization, teaching-learning-based optimization, backtracking search optimization, inverse scattering, and iterative approaches. We summarize several of these methods including electromagnetic time-reversal (TR) and the matched-pulse (MP) approach. We also discuss the issue of soft faults (small impedance changes) and methods to augment their signatures, and the challenges of branched networks. We also suggest directions for future research and development.

완전분해 점검을 통한 장기운영 전투기 전기배선시스템의 신뢰성분석

According to the incresement of aging aircraft, Republic of Korea Air Force (RoKAF) conducted a teardown inspection of aircraft’s EWIS (electrical wiring interconnection system) to determine the status of deterioration and the influence of failure occurrences due to it. The inspected aircraft were the retired fighter jets that had been used for more than 40 years. By analyzing defect type and the defect tendency, RoKAF can establish the necessary measures for the usage extension of their fleet and furthermore, the analysis results can be used as a basic data for the preparation of it’s aircraft aging. EWIS inspection was done throughout careful visual inspection technique by removing all the ducts and pipes located in the fuselage and wings. For the aircraft wiring where no damage was found, the elongation tests were performed to determine the deterioration of wiring according to the location of the aircraft. The connectors, which is the main cause of intermittent failure, were completely disassembled and inspected for internal damage such as corrosion, abrasion, and traces of foreign objects. The detected defects were classified into 4 severity levels based on the type of damage, and the classified defects were weighted according to the criticality which may affects to it’s system to establish the action plan.

Impact of Penetration Wind Turbines on Transient Stability in Sulbagsel Electrical Interconnection System

This paper presents a rotor angle analysis when transient disturbance occurs when wind turbines enter the southern Sulawesi electrical interconnection system (Sulbagsel) both without and with the addition of a Power Stabilizer (PSS) control device. Time domain simulation (TDS) method is used to analyze the rotor angle deviation (δ) and rotor angle velocity (ω). A total of 44 buses, 47 lines, 6 transformers, 15 generators and 34 loads were modeled for analysis after the inclusion of large-scale wind turbines in the Sidrap and Jeneponto areas. The simulation and computation results show the addition of PSS devices to the system when transient disturbance occurs when the winds turbine entering the Sulbagsel electrical system is able to dampen and improve the rotor angle deviation (δ) and the rotor angle velocity (ω) towards better thus helping the system to continue operation at a new equilibrium point.

Simultaneous optimization of electrical interconnection configuration and cable sizing in offshore wind farms

Offshore wind farm (OWF) is the largest renewable energy resource. The electrical interconnection cost of OWFs is a considerable fraction of the overall design cost of the farm. In order to minimize the investment and operational costs, this paper proposes an optimization formulation to find the optimal electrical interconnection configuration of wind turbines (WTs), and the optimal cable sizing simultaneously. This simultaneous minimization of total trenching length and cable dimensions creates a complex optimization problem that is solved by the harmony search (HS) algorithm. In this paper, two distinct methods of full and partial optimal cable sizing are considered to comprehensively assess the optimal interconnection layout of OWFs. Furthermore, various shipping and burying costs as well as various WTs power ratings are considered in order to investigate their impact on the optimal electrical interconnection system. The optimal electrical interconnection design obtained by the HS algorithm corresponds to a lower cost that together with the technological developments can help policy makers increase the use of offshore wind energy as a feasible unlimited renewable resource in their energy production portfolios.

Analysis of the coupling effects on main feeder in more electrical aircraft

Isolation distance is an important consideration in aircraft wiring for coupling effect. according to electrical wiring interconnect system (EWIS) isolation requirements specified in SAE 50881D and airworthiness regulations CCAR 25.1707, explicit isolation distances are not specified. Aircraft wiring is complex or diverse. In order to evaluate coupling effects between the main feeder and signal wire, the three-phase-seven-wire main feeder with 230 VAC, 250 kVA was chosen as the simulation object. The impedance model of three-phase feeder is given with which the coupling effects can be analysed in theory at first. The coupling voltage amplitude is the main evaluation index. In the simulation process, the following cases are chosen: different distances between signal wire and main feeder; signal wire lies in the different phase of the main feeder; isolation distance analysis with types of loads; there exits arc faults on main feeder. Based on the analysis of the simulation results, proposed methods to reduce the coupling effects between wires are given. Through the work in this study, it has some guiding significance for wire or cable laying.

Security Analysis and Preventive Measures of EWIS

In the field of airborne electrical equipment safety, the major concern has been focused on the reliability of the equipment, and the long-term neglect of the connection of each of the airborne electrical equipment cable failure. In order to reduce the probability of wire fault effectively, separate it from the airborne electrical equipment system for research. Firstly, starting from the basic problem of the security of EWIS (Electrical Wiring Interconnection System), the steps of the quantitative analysis of the EWIS fault are given. Secondly, based on the analysis of the failure mechanism of the aviation wire, the advantages and disadvantages of different detection techniques are compared. Finally, the scheme of improving EWIS fault detection ability for the new and old aircraft with different maintenance modes is presented.

Intermittent failure detection of multiple electrical connectors in EWIS

Electrical wiring interconnection system (EWIS) of civil aircraft has been paid more attention in recent years, and intermittent failure detection of electrical connectors in EWIS is a challenging problem. This paper presents a sliding mode observer (SMO) approach for the intermittent failure detection of an aircraft electrical system with multiple connector failures. The mathematical model of the aircraft electrical system which contains multiple connector failures is established for transforming the intermittent failure detection problem into observer-based multiplicative faults isolation and estimation problems. A set of adaptive sliding mode observers are designed to locate the failure connectors preliminarily, the observers can adapt the unknown upper bound of the faults. Furthermore, a fault-reconstruction scheme applying the equivalent output error injection principle is proposed for fault estimation, where the characteristic parameters of connecters are reconstructed to identify the failures. Finally, a numerical example is provided to show the effectiveness of the proposed method.

A methodology to enable automatic 3D routing of aircraft Electrical Wiring Interconnection System

Harness 3D routing is one of the most challenging steps in the design of aircraft Electrical Wiring Interconnection System (EWIS). This is due not only to the intrinsic complexity of the EWIS, but also to the increasing number of applying design constraints and its dependency on any change in the design of the airframe and installed systems. The current routing process employed by EWISdesign is largely based on the manual work of expert engineers, partially supported by conventional CAD systems. As a result, the routing process is quite inefficient, error prone and unable to deliver optimal solutions. Although many harness components are selected from catalogues and the design process is largely repetitive and rule based, it has been found that none or very limited automation solutions, which can significantly decrease the workload of engineers and increase their efficiency, are currently available. In this paper, an innovative approach is proposed to solve the 3D routing automation as an optimization problem. Knowledge Based Engineering (KBE) and optimization methods are proposed to achieve minimum cost routing solutions that satisfy all relevant design rules and constraints. The proposed solution is scalable in terms of constraints, can be deployed on any type of routing environment, and, thanks to the achieved level of automation, able to reduce the process lead time drastically. The basic idea is to achieve optimal EWIS routing solutions by optimizing the position of the harnesses clamping points, which are used as way-points to route the harnesses inside the aircraft digital mock-up. The challenge to solve this optimization problem is that the number and initial value of design variables, namely the number and position of clamping points, are not known a priori. To handle this challenge, a two-step, hybrid optimization strategy has been devised. The first step, called Initialization, uses a road map based path finding method to generate a preliminary harness definition, including the required number and preliminary position of its clamping points. The second step, called Refinement, uses a conventional optimization method to move the position of the clamps and refine the preliminary harness definition aiming for the minimum cost and the satisfaction of all the design constraints. This approach has been implemented into a KBE application connected with a commercial optimization package and tested on several routing cases. The results demonstrate that the proposed method is capable of handling cases of representative geometric complexity and design constraints and delivering proper 3D harness models in full automation.

Impact of pulsed jet actuators on aircraft mass and fuel consumption

Pulsed jet actuators (PJAs) are one of the candidate technologies to be integrated in Fowler flaps to increase the maximum lift coefficient of transport aircraft in the landing configuration. The total system consists of the actuators plus sensors, a piping system to supply pressurized air and a (redundant) power and communication system to provide actuator control. In this paper, it is investigated what increase in the maximum lift coefficient is required to justify the added weight and power off-takes that accompany the integration of pulsed jet actuators. This is done by making an automated design process for the overall aircraft, the piping assembly system, and the electrical wiring interconnection system. These last two sub-systems rely on KBE techniques that automate dimensioning and performance evaluation. A test case is specified that encompasses the design of a typical single-aisle mid-range aircraft with and without the PJA system installed. It is concluded that the introduction of the PJA system requires at least an increase in maximum lift coefficient of 0.2 to justify the increase in system mass and power off-takes. Furthermore, it is shown that if the maximum lift coefficient increases with 0.4, only small reductions in maximum take-off weight (−0.3 %) and operating empty weight (−0.6 %) can be expected, while the total fuel burn remains virtually constant.

Evaluation of the Modeling of an EM Illumination on an Aircraft Cable Harness

This paper describes the approach developed in order to model the electromagnetic response of a cable bundle, part of the electrical wiring interconnection system of a real aircraft, submitted to an external electromagnetic excitation. The aim of this study is to highlight the main challenges in the synthetic modeling and validation of a fully real setup, from the electromagnetic compatibility point of view. Both conducted and radiated excitations have been considered in the electromagnetic global model. The solution is obtained through a cooperative simulation approach involving one 3-D full-wave solver and a multiconductor transmission line solver. The results are compared with measurements and specific tools, such as feature selective validation and integrated error against log frequency, are used to assess the adequacy of the results.