Passenger Car Equivalent Value for Commercial Vehicles: A New Approach

Within the framework of the present paper an attempt has been made to develop a methodology for the calculation of a Passenger Car Equivalent (PCE) factor in order to express the number of commercial vehicles in the equivalent number of passenger cars. The methodology is based on the Highway Capacity Manual, the examination of the international literature and an extended field survey. The research area is the Municipality of Thessaloniki, Greece and specifically 27 at-grade, signalized intersections which were examined. The field survey was performed during two time-periods in order a comparison to be possible

COVID-19′s Pandemic Effects on Bike Sharing Systems: A New Reality for Urban Mobility?

On 11 March 2020, the World Health Organization made the assessment that a new disease (COVID-19) caused by a novel coronavirus (SARS-CoV-2) could be characterized as a pandemic. From that point, a chain reaction of events and difficult decisions requiring action was launched. National governments all over the world announced partial or total quarantine lockdowns in an effort to control the virus’ spreading in order to save as many lives as possible. The effects of the pandemic were multifaceted and transport was not excluded. The current paper examines data regarding the level of usage (provided by the administrator) of bike-sharing systems in three case studies/medium-sized Greek cities (Igoumenitsa, Chania, and Rhodes) and through a statistical analysis identifies if there is a correlation between the implemented measures and the modal choice of the residents. The main results and conclusions of this analysis reveal that the level of usage of these specific bike-sharing systems was significantly increased during the lockdown period compared to the situation before the lockdown and the pandemic in general

The Distance Between Real Time Data and Decision Making in Urban Road Freight Transportation Systems; The Example of the City of Thessaloniki

Road freight transport in urban areas (city logistics) is under study worldwide, especially during the last years, mainly due to its negative impacts to the environment and to the efficient operation of the road network. The modern approach to deal with this rising issue includes the deployment of strategies and measures that take into consideration the conditions prevailing in each study area. In order the decision makers to adopt the proper measures and define the strategy, it is vital for them to have full knowledge of the way an Urban Road Freight Transportation (URFT) system is organized and functions in the field. For this to happen, the decision makers must have under their disposal reliable real time data. After all URFT systems evolve through time and space and it is s crucial that the necessary data not only will be collected correctly but also they will be accessible anytime and anywhere. In this paper a new approach is proposed in order to achieve real time monitoring for URFT systems in order to provide the decision makers with all the necessary data for the case of Greece

The Distance Between Real Time Data and Decision Making in Urban Road Freight Transportation Systems; The Example of the City of Thessaloniki

Road freight transport in urban areas (city logistics) is under study worldwide, especially during the last years, mainly due to its negative impacts to the environment and to the efficient operation of the road network. The modern approach to deal with this rising issue includes the deployment of strategies and measures that take into consideration the conditions prevailing in each study area. In order the decision makers to adopt the proper measures and define the strategy, it is vital for them to have full knowledge of the way an Urban Road Freight Transportation (URFT) system is organized and functions in the field. For this to happen, the decision makers must have under their disposal reliable real time data. After all URFT systems evolve through time and space and it is s crucial that the necessary data not only will be collected correctly but also they will be accessible anytime and anywhere. In this paper a new approach is proposed in order to achieve real time monitoring for URFT systems in order to provide the decision makers with all the necessary data for the case of Greece

Power distribution network reconfigurations for loss reduction and reliability improvement under real operating conditions

The scope of this doctorate dissertation is the solution of the problem of loss reduction by network reconfigurations in Distribution Networks (DNs) in real time, and at the same time the investigation of potential reliability improvement. At first the implementation of a Multiagent System (MAS) that deals with both aforementioned problems is examined. In this analysis it is considered that the installation of MAS in DNs aims to optimize the problem of faults isolation and power restoration to the maximum possible number of customers within the minimum possible time period after the fault occurance. At the same time the analysis investigates whether the MAS’s installation could contribute in real time management of the network for loss reduction due to the increased automation level that incurs. The results of this analysis show that optimization of both problems presupposes universal automation upgrade in the DN and based on feasibility studies that are presented, the payback time for the required investments could be determined. Next, o novel algorithm that incorporates load variations in the problem of network reconfigurations for loss reduction is presented. It is assumed that the implementation of the proposed algorithm simulates real operational conditions since it takes into account the stochastic load variations and thus, it examines the influence of these variations to the necessary switching operations for optimal reconfigurations. The algorithm is implemented in 3 DNs of the published literature and in a real segment of the urban DN of Thessaloniki. Useful conclusions are depicted regarding the tolerance in load variations that defines whether a new reconfigured topology should be searched or not for real operational conditions. Finally, a novel method is proposed concerning selective automation upgrade in DNs that result in near optimum management for loss reduction in real time, and at the same time contributes in significant reliability improvement.Η παρούσα διδακτορική διατριβή πραγματεύεται την επίλυση του προβλήματος μείωσης των απωλειών στα ΔΔΗΕ μέσω ανασχηματισμού της τοπολογίας τους και ταυτόχρονα της βελτίωσης της αξιοπιστίας τους σε πραγματικές συνθήκες λειτουργίας. Αρχικά εξετάζεται η δυνατότητα χειρισμού των ΔΔΗΕ σε πραγματικό χρόνο με την εφαρμογή ενός Πολυπρακτορικού Συστήματος (ΠΣ) για την επίλυση των δύο προαναφερθέντων προβλημάτων. Σε αυτή την ανάλυση θεωρείται ότι η εγκατάσταση του ΠΣ στις γραμμές ΜΤ των ΔΔΗΕ πραγματοποιείται για την βελτιστοποίηση του προβλήματος απομόνωσης σφαλμάτων και αποκατάστασης τροφοδοσίας στο μέγιστο δυνατό αριθμό καταναλωτών. Ταυτόχρονα εξετάζεται και η δυνατότητα χειρισμών για μείωση απωλειών σε πραγματικό χρόνο εφόσον η εγκατάσταση του ΠΣ συνεισφέρει στην αύξηση του επιπέδου αυτοματισμού στο δίκτυο. Η ανάλυση που πραγματοποιήθηκε δείχνει ότι η βέλτιστη επίλυση αυτών των προβλημάτων απαιτεί καθολική αναβάθμιση του επιπέδου αυτοματισμού και οι οικονομοτεχνικές μελέτες που συντάχθηκαν καθόρισαν το απαιτούμενο χρονικό διάστημα για την απόσβεση των προβλεπόμενων επενδύσεων για νέο αναβαθμισμένο εξοπλισμό στα δίκτυα. Στη συνέχεια αναπτύσσεται ένας αλγόριθμος για την ενσωμάτωση των μεταβολών των φορτίων στο πρόβλημα μείωσης των απωλειών στα ΔΔΗΕ μέσω ανασχηματισμού της τοπολογίας τους. Θεωρείται ότι μέσω της διαδικασίας που υλοποιείται από τον αλγόριθμο προσομοιώνονται πραγματικές συνθήκες λειτουργίας εφόσον λαμβάνονται υπόψη οι στοχαστικές μεταβολές των φορτίων, και επιδιώκεται η ανίχνευση της επίδρασης αυτών των μεταβολών στους απαραίτητους διακοπτικούς χειρισμούς. Ο αλγόριθμος εφαρμόζεται σε 3 πρότυπες τοπολογίες από τη διεθνή βιβλιογραφία και σε ένα πραγματικό τμήμα του ΔΔΗΕ της Θεσσαλονίκης. Μέσω των προσομοιώσεων που υλοποιήθηκαν εξάγονται χρήσιμα συμπεράσματα για την ανοχή στις μεταβολές των φορτίων που επιβάλλει την ανάγκη διερεύνησης καινούργιας λύσης για το πρόβλημα μείωσης των απωλειών σε πραγματικό χρόνο. Τέλος με βάση τα αποτελέσματα του προτεινόμενου αλγορίθμου προτείνεται μία προσέγγιση επιλεκτικής αναβάθμισης του επιπέδου αυτοματισμού στα ΔΔΗΕ που επιφέρει σχεδόν βέλτιστη διαχείριση σε πραγματικό χρόνο για μείωση των απωλειών και ταυτόχρονα σημαντική βελτίωση της αξιοπιστίας τους

A Two-Stage EV Charging Planning and Network Reconfiguration Methodology towards Power Loss Minimization in Low and Medium Voltage Distribution Networks

The topic of power loss reduction in distribution systems has gained significant attention over recent years. Despite the efforts of the European Union towards the minimization of power losses, the decarbonization of the transport sector has raised several concerns, since charging overlaps of Electric Vehicles (EVs) can cause extensive power losses and power quality issues. Considering these, the present paper proposes a two-stage EV charging planning and Network Reconfiguration (NR) methodology, addressing the problem of power loss minimization in both Low-Voltage (LV) and Medium-Voltage (MV) Distribution Networks (DNs), respectively. In the first stage, considering the key role of the aggregator, the EV charging planning is applied to LV DN. In the second stage, the NR technique is applied to the MV DN, by taking into account the hourly power demand of LV DNs as obtained by the aggregators. The proposed methodology has been applied on a benchmarked MV network for which each node is represented by a real LV network. The results indicate that the proposed methodology could yield up to a 63.64% power loss reduction, in respect to the base scenario, i.e., no charging planning and no NR are applied

Quantifying the Benefits from a Major Infrastructure Improvement: The Case of Thessaloniki Western Ring Road Upgrade to Eliminate at Grade Signalised Intersections

Thessaloniki is the second largest city in Greece and its transportation system (development and operation) is hampered by the city’s geographical position and surrounding relief. Specifically, the city has been developed and expanded through the years along the coastline, the sea boundary on the southwest, and a second physical boundary, a forest, on the east side. The Thessaloniki Ring Road (divided in western and eastern part) was constructed in the early ‘90s, in order to relief the road network of the city centre from the transit traffic and confront the gradually increasing congestion. The absence of alternatives other than road transport and the increase of car ownership over the years led to an increase of motorized traffic. So even that this Ring Road had been designed to serve 30,000 vehicles daily it became to serve more than triple traffic just before the impacts of the economic crisis on transport and mobility have been made visible

A Comparison of Feature Selection Techniques for Neural Network Based Load Forecasting

The performance of neural networks in load forecasting tasks is highly influenced by the selection of the inputs. This selection is either problem specific or is relied on the literature. The scope of the present study is to compare two features (i.e. inputs) selection methods based on metaheuristics. Thus, the inputs selection process is treated as an optimization process. The test case involves the day-ahead load forecasting of the aggregated load covered by a distribution substation in a large urban area. © 2019 IEEE

Congestion management in coupled TSO and DSO networks

This paper proposes a three-stage coordination methodology to optimally manage congestion in day-ahead operation planning for Transmission Systems (TS) and Distribution Systems (DSs). The first stage provides the day-ahead model (DAM) results for the power units in the TS, and Energy Storage Systems (ESSs) and Electric Vehicles (EVs) in the DSs. The second stage applies the DAM results to the modelled TS to reveal any congestion issues. If congestion is depicted the need for congestion management (CM) by the Transmission System Operator (TSO) arises. Thus, the TSO performs an AC Optimal Power Flow (OPF) analysis, under power loss minimization, to provide the redispatch schedule in the TS and quantify the power transactions between TSO and the Distribution System Operators (DSOs). Finally, the DSOs examine if they can deliver these power transactions without congestion in their DSs, by applying AC OPF to minimize power losses. If this is not possible, then a relaxation scheme is applied to these power transactions in order to define the maximum DSO flexibility without congestion in the DS. The proposed methodology is applied to the simulated Greek TS and the results indicate that it can optimally redispatch the available assets with a coordinated interaction between TSO-DSO(s)