Bus Node Research Articles

The value of waiting spaces: Tourists’ willingness to pay for high-quality bus terminals

Transport quality has long been recognized as an important factor in influencing travelers’ behavior, and transport terminal quality undoubtedly plays no small part. Indeed, transit promotion policies explicitly based on qualitative factors and high-standard architecture are increasingly being adopted in designing new bus terminals and stops. High architectural standards can be found in several bus terminals worldwide. Nevertheless, the literature in transport sector has yet to explore the impact of bus terminal “hedonic quality” on users’ behavior or use their willingness to pay (WTP) in cost–benefit analyses or other transport policy applications. Hedonic value is here intended as the aggregate of all elements related to travelers’ pleasure in spending time in a terminal where architectural beauty and the passenger services offered are arguably the most visible and representative attributes. Within this context, we propose a quantitative analysis of the perceived hedonic value of bus nodes in terms of users’ WTP (pure preference) for a high-quality bus terminal. To this end a discrete choice experiment based on a visual immersive experience was performed, and data were collected from 324 residents of Milan (Italy) traveling for tourism. Different binomial Mixed Logit models with panel data and random coefficients were estimated for the purpose. Monetary valuation of pure preference for using a high-quality bus terminal was estimated with a mean of about 25 % of the average trip cost observed for the case study considered. This pure preference means that the Italian tourist is willing to spend up to €4.35/trip more for a high-quality bus waiting space or travel up to 28.2 min/trip more, instead of using a traditional bus terminal for the same trip. Category-specific analyses show that females > 30 years old have a greater pure preference for a high-quality bus terminal (up to + 220 %) against males and young users. The employed also have a higher (+42 %) pure preference for the beauty of a bus terminal against others. The results of this paper should be compared with those from other case studies as they have a potential impact for transportation planning applications, underling the importance of also incorporating “hedonic quality” as explicit design variables for new/revamped transportation hub. At the same time, new challenges are posed for modeling user behavior and determining quality-related indicators and measures.

A Novel DWT-ERT-based Fault Location for Distribution Network

Background: A new DWT-ERT-based fault location method is suggested in the IEEE test feeder. Objective: The fault location approach in the distribution network has been proposed in this pa-per that utilizes the discrete wavelet transform (DWT) and ensemble regression tree (ERT). Methods: The fault location methodology has been validated by simulations conducted on an IEEE 13 bus node test feeder. Results: The results show that the suggested solution has low compute burden and memory re-quirements, and is unaffected by system and fault situations. Conclusion: In this study, the fault location approach for the distribution system employing DWT and ERT has been proposed.

Single-phase grounding line selection method for closed-loop distribution network adapted to medium voltage microgrid access

Aim: The access of the medium-voltage (MV) microgrid changes the radial structure of traditional distribution networks, causing the distribution network to operate in a closed-loop manner. The closed-loop operation complicates the fault characteristics of the distribution network, and the traditional single-phase grounding (SPG) line selection method is no longer applicable. Therefore, it is necessary to propose a new targeted SPG line selection method. Methods: This paper analyzes the network structure of MV microgrids and MV distribution networks and establishes a multi-level closed-loop operation distribution network model with MV microgrid access. Then, the SPG fault characteristics of the closed-loop operation distribution system under the small current grounding mode are analyzed from the perspective of two-level bus nodes. Furthermore, based on the analysis of fault characteristics, a closed-loop operation distribution network line selection method suitable for microgrid access is proposed, and a detailed design is carried out in terms of equipment configuration and communication schemes, forming a relatively complete automatic line selection system. At the same time, the proposed line selection scheme is based on the two-level bus nodes, which can be analogously applied to the multi-level closed-loop operation distribution network. Results: The simulation results show that the proposed line selection scheme can be effectively applied to the closed-loop operation distribution network with MV microgrid access. Conclusion: The traditional SPG line selection method will have misjudgment problems after the MV microgrid is integrated into the distribution network, but the line selection method proposed in this paper has good adaptability.

A Review of Various Optimization Strategies for Handling Optimal PMU Placement Problems

Abstract: The Phasor Measurement Unit (PMU) is the most fundamental power system technology that is utilized to protect, monitor, and control power networks. It not only allows real-time, synchronized voltage measurements on the buses but also the current phasor of lines connected to the buses where these PMUs are placed. The positioning of PMUs at each bus node is unnecessary and is restricted by the installation's high cost and complexity. As a result, the fundamental goal of Optimal PMU placement (OPP) is reducing the total no. of PMUs along with maximum observability, while simultaneously considering measurement redundancy. There are several methods for fixing this problem, and they fall into two categories: Metaheuristic methods and mathematical approaches. This study examines a variety of optimization strategies for handling OPP problems

Power Flow Analysis of Electrical Network Systems Using Gauss-Seidel Method and Python

This study aims to analyze the power flow in a 150kV radial power system on the island of Bali, the reason the author uses the Bali island system is because the number of busbars in the system is not too many and the data on the system is known. The problem of this research is limited by determining the voltage, power flow, and power losses in the system. The method used in this study is the Gauss-Seidel method through simulation with the help of Visual Studio Code software and the Python 3.9.2 program. The simulation is carried out by producing a total of 8 iterations. The simulation is carried out to find the parameters of the load voltage, apparent power on the slack bus, current, power flow and power losses on the line. The simulation results show that, under a load condition of 70% of the load transformer capacity, the voltage at the load bus node experiences a voltage drop, reaching 4.48% at bus 10. So when the system operates for generation conditions, the power that can be generated is 1,275.6 MegaWatt of the total generator installed, and the power delivered to each bus node is 2,090 MVa and the power losses in the system are 3.69% of the total power distributed to the bus nodes

Multi-Robot Distributed Communication in Heterogeneous Robotic Systems on 5G Networking

This work aims at new opportunities for the development of the robot communication network. Besides, a robot operation and decision control method driven by Digital Twins (DT) is designed to utilize lasers in a virtual environment. The multi-agent is integrated with the Proximal Policy Optimization (PPO) algorithm, forming the Muti-PPO algorithm for robot path planning. In addition, a consistent hashing algorithm is introduced and optimized as a Weighted Consistent Hash of Multiple Mappings (WCHMM) algorithm with multiple mappings. The experimental results indicate that the average task execution time of the WCHMM algorithm in the case of three bus nodes is 8.09s, which is 32.47 percent and 21.38 percent lower than the task execution time in the case of a single bus node and two bus nodes, respectively. The multi-robot distributed communication system based on Service Oriented Architecture (SOA) gives full play to the various inherent advantages of the multi-robot system.

Design and Evaluation of a 180 nm Powerline Communication ASIC for Harsh Environment

Modern complex drilling systems contain communication nodes like sensors, actuators, and controllers, spread along the lower end of a drill string. Here, temperatures of more than 150°C and pressure levels up to 200MPa are present. These environmental conditions and mechanical shocks, are extremely challenging for the reliable use of electronic components. A powerline communication system is designed and evaluated to establish a robust communication channel with low amounts of wiring. This system can operate on highly distorted physical transmission channels by adding redundancy at the sender that can then be used to correct errors at the receiver. In order to synchronize the real-time clocks among different powerline stations, a new preamble extension approach that enables precise time synchronization between multiple bus nodes is added. After design and verification, this system was manufactured in XFAB 180nm Silicon-On-Insulator (SOI) technology allowing operating temperatures of up to 175°C. The die size is 5.25 mm × 5.25 mm and contains a complete HomePlug 1.0 communication stack with an environment for boot, interfacing, and debugging. Its data rate reaches 6.1Mbit/s using the fastest transmission mode and the theoretical maximum of 0.55Mbit/s in the robust OFDM (ROBO) mode, which is of particular interest for harsh environment applications. After verifying the fabricated die, a Printed Circuit Board (PCB) for climate chamber evaluation was designed and fitted. Measurements in this chamber carried out a maximum ambient temperature of 190°C for communication with a minimum self-heating of the die of 20°C measured at room temperature. In combination, this is 35°C above the specification of the technology process. The timing synchronization evaluation showed a precision of 55.6ns over the temperature range from -30°C to 185°C, which is as low as 1.5 clock cycles. Power measurements of up to 190°C have shown an average power consumption increase of only 63μW/K below 150°C and a maximum increase of 394μW/K above 150°C. To the best of the authors’ knowledge, this is the first high-temperature evaluation of a powerline communication ASIC, which is particularly designed for a drilling system’s harsh environment.

A Flicker Source Location Method Based on Wide-Area Information

The voltage fluctuation and flicker level are important indicators for evaluating power quality. Correct identification of flicker sources can effectively help to improve power quality. To solve the problems of insufficient accuracy and lack of propagation path analysis in current flicker source location research, a flicker source location method based on wide-area information is proposed. Based on the frequency-amplitude binary characterization, the main components of the voltage data from each bus node are used to determine the main frequency of the voltage fluctuation. By comprehensively comparing the voltage data of each node at the main frequency, the flicker source can be located. Simulations in PSCAD/EMTDC verify that the flicker source in the regional power grid is accurately detected and the flicker propagation path is identified by the proposed method.

Vector correlation learning and pairwise optimization feature selection for false data injection attack detection in smart grid

Abstract This paper mainly studies vector-related learning and pairwise optimization feature selection for false data injection attack detection in smart grid. In order to provide experimental detection of false data injection attacks, this article will conduct a detailed analysis of the power system segmentation. This paper comprehensively considers the similarity of nodes, security control and confidentiality strategies to complete the optimal partition. Next, we preprocess the measurement data. In order to improve the adaptability of the algorithm structure to the grid structure and further improve the accuracy and convergence speed of the algorithm output, a differential evolution algorithm with swarm intelligence is proposed. Obtain a higher-precision state estimate useful for detecting bad data. In the experiment of this article, if false data account for 20% of all data, the detection accuracy exceeds 75%. As the number of experimental groups increases, the detection accuracy of only one type of false data that does not meet the rules will continue to increase, but the detection accuracy of other types of false data will not change much, but the overall detection accuracy will become higher. Experimental results show that the detection framework can not only effectively detect and identify false data injection attacks on multiple bus nodes, but also has high detection accuracy and can effectively recover false data.

A Generic Small-Signal Stability Criterion of DC Distribution Power System: Bus Node Impedance Criterion (BNIC)

The dc distribution power system has drawn widespread attention and rapidly developed in recent years; however, its stability issue is one of the urgent challenges, requiring much attention. In previous stability studies, the line impedance network is often overlooked, which is convenient for the geographically centralized systems, but inaccurate for the distributed systems. In this article, the modeling and stability criteria of these two systems are simultaneously studied. For the distributed systems, first, the transfer functions from each input voltage or current disturbance to the bus voltage are derived. On this basis, the sufficient and necessary condition for the system stability is discussed. Subsequently, a bus node impedance criterion (BNIC) is proposed to assess the small-signal stability of the dc distribution power system. For the centralized systems, by ignoring the line impedance network, its small-signal model can be deduced by the distributed system, and the proposed BNIC is proved to be still valid. In addition, some existing impedance-based stability criteria are analyzed and compared with the proposed BNIC. Finally, the correctness and effectiveness of the proposed BNIC are verified by the cases study and experiments.

A New Standalone Tool for DC‐Equivalent Network Generation and GIC Calculation in Power Grids With Multiple Voltage Levels

AbstractSpace Weather phenomena pose a major socio‐economic threat due, in part, to the vulnerability of power network transformers to geomagnetically induced currents (GIC). In 1985, Lehtinen and Pirjola (LP) provided a method to calculate GICs in a single‐voltage‐level network. The need to account for lower voltages has caused the proliferation of GIC risk assessments applied to power grids with multiple voltages. We hereby present a tool to systematically generate the direct currents (DC)‐equivalent of a multiple‐voltage‐level network. The LP and Nodal Admittance Matrix methods are the most popular schemes to compute the GIC from the resulting equivalent network by solving the circuit laws for the earthing current or the voltage at each node, respectively. A new scheme is presented here that solves the circuit laws for the current flowing between the bus nodes and the neutral point which, unlike LP, requires no (infinite‐resistance) earth connections for the buses. The number of equations/unknowns of the resulting GIC matrix equation is reduced compared to the traditional methods, thus optimizing the computational cost ‐an advantage that becomes important for large networks‐, while keeping a good condition of the design matrix associated with the inversion. Examples are shown for different test cases and a standalone computationally efficient code is provided.

Grid‐forming requirements based on stability assessment for 100% converter‐based Irish power system

The fault response of a 100% converter-based system can be significantly different to that of a synchronous generator-based system, considering the lower capacity headroom, but flexible control capability, of power electronic converters. The system response is investigated for an Irish grid under balanced three-phase faults comprising of 100% converter-based generation: grid-forming (GF) and grid-following (GL). Electro-magnetic transient (EMT) simulations show that a system consisting only of GF converters (all droop control, all dispatchable virtual oscillator control, or a mix of both) is robust against three-phase faults, with little variation in performance, despite the fault location or choice of GF control methods. However, the rating and location of GF converters are critical to operating the grid securely in the presence of both GF and GL converters. Assuming that individual converter bus nodes are either GF or GL, a minimum GF requirement (by capacity) is found to be 37–40%, with these GF converters located close to the major load centres. Assuming instead that individual generation nodes consist of a mix of GF and GL converters, it is found that the GF requirement can be relaxed by 8–10%.

Bifurcation analysis of the influence of generator excitation forms on system voltage stability

Based on a typical power system model, this paper simulates the scenario of the increase of active power output of a proximal generator around certain bus node and applies bifurcation theory to study the influence of different excitation forms on system voltage stability after reaching generator excitation saturation. With numerical bifurcation analysis software MATCONT, the simulation analysis results show that the smaller the excitation output upper limit value is, the earlier the bus voltage reaches the Hopf bifurcation with the increase of active power output. In the case of self-shunt excitation, the output of the excitation upper limit value is constrained by the generator terminal voltage. Therefore, the bifurcation point in this case occurs earlier than that in the case of separate excitation.

CAN Implementation and Performance for Raman Laser Spectrometer (RLS) Instrument on Exomars 2020 Mission

The use of CAN bus in space applications has increased during the last fifteen years. The need of standardizing not only the physical and link layers but also the higher layers protocol to meet spacecraft specific constraints or requirements, such as bus redundancy management, node monitoring and synchronization, has aroused. Therefore, a Working Group on CAN bus was stablished by ESA in collaboration with European Industry and Space Agencies, whose effort gave as result the publication of ECSS-E-ST-50-15C in 2015. This standard defines CAN protocol extensions for space use and specifies the optional use of the CANopen standard as higher layer to be used over CAN bus. The ExoMars Mission was chosen as spreadhead for the application of this standard. The present paper provides an experience report on this novel standardized use of CAN/CANopen in Space, in particular in the Raman Laser Spectrometer (RLS) that will be boarded into the Rover of ExoMars 2020. Even though RLS makes use of considerably long science telemetries (up to around 2Mbytes) CAN has been designated as its only data interface. We report on software, hardware and data transmission performances, as well as brief description on redundancy and synchronisation of this CAN implementation.

A Double-Transistor Double Primary–Winding Flyback Converter for Marine Resources Monitoring Equipment

Li, J.; Wu, H.; Xu, T., and Lin, P., 2020. A double-transistor double primary–winding flyback converter for marine resources monitoring equipment. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 340–344. Coconut Creek (Florida), ISSN 0749-0208.The DC bus power-supply mode is the most convenient for marine resources monitoring equipment, and secondary electric power supplies at power supply nodes are featured by a wide variation range of input voltage and high electromagnetic interference (EMI) requirements. A double-transistor double primary–winding flyback converter with wide input range, low EMI noise, and active auto-starting function was designed in this study. The main circuit of this converter solves the withstanding voltage problem of switching tube via series connection of double transistors under high-voltage condition. Through the intertexture structure of the double primary windings, the main transformer reduces the drain-source voltage spike of the switch and effectively mitigates the common-mode EMI noise at output end. The large starting circuit loss is solved, and the converter efficiency is improved under wide input range through the active auto-starting circuit. The experimental results show that when the bus node voltage varies within a wide range of 100 V–1000 V, the converter efficiency is always greater than 85%, and EMI performance is superior, thus satisfying the requirements of bus power-supply system.

Novel framework for investment prioritisation based on flexibility needs assessment

This study presents a novel framework for investment prioritisation in a distribution network by performing a flexibility needs assessment with regards to power quality parameters. Power range and time instances of activation are identified with a view of maintaining normal operation. A step forward is made by incorporating the importance of the flexibility needs assessment in investment prioritisation as part of the network expansion planning. The proposed framework consists of three procedures: input data preparation, operational calculations and the post-processing of results, which are used to quantify the flexibility needs and propose an investment prioritisation list. A bus node, which forms a part of the existing distribution network in Slovenia, is used to demonstrate the general applicability of the framework. As a result, an investment prioritisation list was compiled by assessing the flexibility needs. The secure power supply buffer of the node is determined, while the quantification of the flexibility power range and time instances of activation are also provided in order to further mitigate network constraints. Apart from providing valuable information to network operators, the newly proposed framework lays the foundation for aggregators and market players to plan and self-balance their portfolio and position when providing flexibility market services.

An approach of multistage distribution system network expansion planning considering investment, operational cost and reliability of system

Objectives: To solve the Multistage Distribution System Planning (MSDSP) problem by a solution strategy based on investment cost, operational cost and reliability of electric power distribution system network. Method: A distinctive multi- objective function model has been developed to compute the expansion period wise cost of investment, operational cost (cost of energy losses in the distribution network) and system reliability is evaluated in terms of Non-Supplied Energy Cost (NSEC) under contingency conditions. Findings:The computed result presents the cost of investment of new equipment, operational cost and NSEC for each period of network expansion along with overall cost of investment in all periods of network expansion. Results obtained also demonstrate the corresponding bus nodes voltages in per unit (pu) for each period of network expansion to satisfy the technical constraints of the voltage profiles. Novelty: A distinctive multi-objective function model is developed to solve MSDSP problem with planning & operational constraints and results obtained encourages the prospects related to the technical, economical and system reliability issues of electric power distribution system network. Keywords: Multistage distribution system planning (MSDSP); investment cost;operational cost; distribution system reliability; non-supplied energy cost(NSEC); load flow studies

Real Time Stability Analysis with Distributed Generation in Multi-fed RDN Using PMU and Feed Forward Technique

— This paper analyses the stability issues of a multi-fed radial distribution network (RDN) by evaluating its states using a state-of-the-art technique under different operating condition. In its working principle, the entire RDN is visualized as a network comprising of N number of 2-bus sections cascaded sequentially. The required bus states are evaluated using the feed forward technique on the basis of the measurements from customized PMU(s) and smart meters (SMs) placed at suitable locations within the RDN. The inherent single iterative feature of the feed forward technique reduces the computational time leading toward the possibility of real time monitoring. The stability indices are evaluated based on these measured parameters for different case studies viz. normal, contingent, and faulty as well as inclusions and/or exclusions of renewables at different bus nodes conditions. The stability indices are also analyzed for inclusions and/or exclusions of renewables at different bus nodes. The findings of the analysis are summarized to propose the prediction about the abnormal running of the segment(s) of this multi-fed RDN in real time. The MATLAB simulation shows the nature of variation in voltage and power angle profiles of different buses with change in positions of DERs.

Optimizing wind turbine participation for frequency regulation in large scale power systems

This paper proposes an optimization approach for the participation of wind turbines in large scale power systems. The wind turbine participation optimization aims to regulate the droop slopes and the synthetic inertia of the aggregated wind turbines to command the power contribution of wind turbines proportional to their power ratings in the primary frequency response schemes. A reduced second order model of power system is firstly presented to simplify the analysis of large scale power system. Meanwhile, the internal dynamics of general wind turbines are analyzed and the concept of stability margin is proposed to describe the wind turbines' capability of enduring frequency dips at the bus node. A convex optimization based approach is then presented to regulate the droop slopes and synthetic inertia of the wind turbines incorporating their stability margin. Five case studies are conducted in New England 39-bus system, IEEE 118-bus power system and the Polish 3375-bus system. The simulation results indicate that the proposed approach is capable of transiting the bus frequency to the new steady state in a smoother and more stable manner.

Distributed Economic Dispatch for Energy Internet Based on Multiagent Consensus Control

We consider the economic dispatch (ED) for an Energy Internet composed of energy routers (ERs), interconnected microgrids, and main grid. The microgrid consists of several bus nodes associated with distributed generators (DGs) and intelligent control units (ICUs). We propose a distributed ED algorithm for the grid-connected microgrid, where each ICU iterates the estimated electricity price of the distribution system and the estimation for the average power mismatch of the whole microgrid by leader-following and average-consensus algorithms, respectively. The ER iterates the incremental power exchanged with the distribution system. By constructing an auxiliary consensus system, we prove that if the communication topology of the Energy Internet contains a spanning tree with the ER as the root and there is a path from each ICU to the ER, then the estimated electricity price of the distribution system converges to its real value, the power supply and demand achieves balance and the ED achieves optimal asymptotically. Furthermore, we propose an autonomous distributed ED algorithm covering both grid-connected and isolated modes of the microgrid by feeding back the estimated average power mismatch for updating the incremental costs with penalty factor. It is proved that if the communication topology of the microgrid is connected and there exists an ICU bidirectionally neighboring the ER, then the microgrid can switch between the two modes reliably. The simulation results demonstrate the effectiveness of the proposed algorithms.