Papers by Nikolaos Manousakis
Iet Generation Transmission & Distribution, Nov 1, 2015
This study presents an algorithmic approach for optimal placement of phasor measurements units (P... more This study presents an algorithmic approach for optimal placement of phasor measurements units (PMUs) to ensure complete observability in the presence of conventional measurements and zero injection buses. The financial or technical restrictions prohibit the deployment of PMUs at every bus, which in turn motivates their strategic placement around the power system. Topology-based transformations are implemented for observability analysis. The PMU problem allocation is optimized based on measurement observability criteria for achieving solvability of the power state estimation. The Branch-and-Bound algorithm (BB) and Binary-Coded Genetic algorithm (BCGA) are applied to solve the optimization problem. The BCG algorithm incorporates a special truncation procedure to handle integer restrictions on decision variables along with a penalty parameter approach for handling constraints. The proposed algorithms detect the minimum PMU number and their locations required to make the power system numerically observable. The proposed algorithms are applied to IEEE systems as well as a large-scale system with 1011 buses to exhibit the applicability of them to practical power systems. The solution points located using the BCGA are interpreted as nonstrict global minima since they are in complete agreement with those obtained by the BB algorithm in solving the (zero-one) constraint integer linear program.
Processes, May 18, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Τις τελευταίες δεκαετίες, η βιομηχανία ενέργειας ισχύος υπόκειται σε πολλαπλές αλλαγές εξαιτίας τ... more Τις τελευταίες δεκαετίες, η βιομηχανία ενέργειας ισχύος υπόκειται σε πολλαπλές αλλαγές εξαιτίας της απελευθέρωσης της αγοράς. Στις μέρες μας, οι ανταγωνιζόμενες μεταξύ τους αγορές ενέργειας παρέχουν επαρκή παραγωγή ισχύος, τεχνολογικές καινοτομίες, και πιο φθηνά τιμολόγια. Σ’ αυτό το περιβάλλον, η ασφαλής λειτουργία των ηλεκτρικών συστημάτων απαιτεί στενή παρακολούθηση των συνθηκών λειτουργίας τους. Αυτό επιτυγχάνεται μέσω των κέντρων ελέγχου, που συγκεντρώνουν τα δεδομένα που λαμβάνονται από διάφορους υποσταθμούς για να παράσχουν μία εκτίμηση των φασιθετών τάσης, των λήψεων των μετασχηματιστών, των καταστάσεων των διακοπτών, και άλλων μετρούμενων και μη μετρούμενων ηλεκτρικών μεγεθών και παραμέτρων του ηλεκτρικού συστήματος. Παραδοσιακά, τα διαθέσιμα δεδομένα είναι μετρήσεις οι οποίες παρέχονται από το σύστημα SCADA, και περιλαμβάνουν ενεργές και άεργες ροές και εγχύσεις ισχύος, όπως επίσης μέτρα τάσεων και καταστάσεις διακοπτικών στοιχείων. Με την έλευση του παγκοσμίου συστήματος προσδιορισμού θέσης (GPS), το σύνολο των μετρήσεων διευρύνθηκε ώστε να συμπεριλάβει τις διαθέσιμες συγχρονισμένες μετρήσεις φασιθετών, οι οποίες παρέχονται από τις μονάδες μέτρησης φασιθετών (PMUs). Αυτές είναι μετρητικές συσκευές που παρέχουν την απαραίτητη πληροφορία για την ελαχιστοποίηση και τον έλεγχο των απωλειών ισχύος και την αποφυγή προβλημάτων όπως οι μεγάλου μεγέθους διακοπές παροχής ισχύος. Αυτή η διατριβή επικεντρώνεται στα οφέλη από τη χρήση συγχρονισμένων μετρήσεων φασιθετών και μονάδων PMU με σκοπό την βελτίωση της εποπτείας και του ελέγχου του ηλεκτρικού συστήματος. Τα οφέλη διερευνώνται σε σχέση με την ανάλυση της παρατηρησιμότητας του μετρητικού συστήματος, τη βέλτιστη τοποθέτηση μονάδων PMU και την εκτίμηση κατάσταση του ηλεκτρικού συστήματος. Αρχικά, η διατριβή παρουσιάζει απλούς και αποτελεσματικούς αλγορίθμους που αφορούν την ανάλυση παρατηρησιμότητας, τον έλεγχο και την αποκατάσταση, για συστήματα που περιλαμβάνουν τόσο συμβατικές όσο και μετρήσεις φασιθετών. Καινοτόμες μέθοδοι βέλτιστης τοποθέτησης μονάδων PMU βασισμένες σε ευρετικούς και μαθηματικούς αλγορίθμους που διασφαλίζουν μέγιστη περίσσεια μετρήσεων και λαμβάνουν υπ’ όψιν την ύπαρξη ή μη συμβατικών μετρήσεων, επίσης προτείνονται. Τέλος, παρουσιάζονται διατυπώσεις του προβλήματος εκτίμησης κατάστασης βασισμένες στα ελάχιστα σταθμισμένα τετράγωνα, που περιλαμβάνουν τόσο κλασικές όσο και μετρήσεις φασιθετών τάσεως και ρεύματος. Οι προτεινόμενες διατυπώσεις επεξεργάζονται ταυτόχρονα ή μη τους διαφόρους τύπους μετρήσεων και αποφεύγουν οποιοδήποτε αριθμητικό πρόβλημα μπορεί να προκύψει από την χρησιμοποίηση πολικών ή καρτεσιανών συντεταγμένων των φασιθετών ρεύματος.Τα αποτελέσματα δείχνουν ότι η στρατηγική τοποθέτηση μερικών μονάδων PMU στο σύστημα μπορεί να αυξήσει σημαντικά την περίσσεια των μετρήσεων, και με τη σειρά της να βελτιώσει την ικανότητα ανίχνευσης και εντοπισμού των εσφαλμένων δεδομένων.
This paper presents a semidefinite programming (SDP) formulation with binary decision variables, ... more This paper presents a semidefinite programming (SDP) formulation with binary decision variables, for the optimal placement of phasor measurement units (PMU), considering the existence of conventional measurements and the impact of limited channel capacity (OPP-LCC). The proposed problem minimizes a linear objective function subject to linear matrix inequality (LMI) observability constraints. Simulations, using a Matlab-based SDP software, are conducted on different IEEE systems to prove the validity of the proposed method.
Iet Generation Transmission & Distribution, Nov 3, 2020
The transition from the conventional power systems to smart grids has led to the modernisation of... more The transition from the conventional power systems to smart grids has led to the modernisation of the measuring infrastructure used for their monitoring and control. Among the devices used to accomplish these tasks, phasor measurement units (PMUs) play a key role since they can provide extremely accurate synchronised voltage and current phasor measurements. The optimal PMU placement (OPP) problem, which focuses on minimising the number of PMUs for full system observability, has long been a popular research topic. The vast majority of the available OPP techniques have treated each transformer tap setting (voltage turns ratio and phase-shifting angle) as a fixed network parameter. Such an assumption can lead to misdirecting residuals in adjacent valid measurements when the modelled tap setting is incorrect. The aim of this study is to propose a substation-oriented OPP method based on a binary semidefinite programming algorithm, considering the observability of the transformer tap settings and the limited PMU channel capacity. The method is illustrated using an 8-bus test system. Numerical results using different size IEEE systems are presented and discussed. The proposed approach is further applied to the Polish 3120-bus system to show its efficacy in solving the OPP problem for large-scale power systems.
IEEE Transactions on Instrumentation and Measurement, Jun 1, 2020
This paper presents an efficient and comprehensive method to find out the minimum number and corr... more This paper presents an efficient and comprehensive method to find out the minimum number and corresponding locations of phasor measurement units (PMUs) guaranteeing full numerical observability of a power system as well as maximizing the measurement redundancy in conjunction with pre-existing conventional measurements. Furthermore, the effect of the number of available channels of PMUs on their optimal placement can be taken into account. The proposed optimal PMU placement (OPP) formulation is extended to consider the case of two types of contingencies, single PMU loss and single branch outage. The objective in the OPP method is the numerical observability, unlike the majority of earlier works which are based on topological observability and do not always ensure numerical observability required for successful execution of state estimation. The problem is formulated as a binary semidefinite programming model with binary decision variables, minimizing a linear objective function subject to linear matrix inequality observability constraints. The binary semidefinite programming problem is solved using an outer approximation scheme based on binary integer linear programming. The effectiveness of the proposed method is verified on different IEEE test systems.
IEEE Transactions on Power Systems, Jul 1, 2016
International Transactions on Electrical Energy Systems, Apr 15, 2018
This paper presents a hybrid state estimator based on measured data delivered by unsynchronized a... more This paper presents a hybrid state estimator based on measured data delivered by unsynchronized and synchronized sensors, taking into account their different refresh rates. The proposed algorithm is based on a reference-free problem formulation, using Cartesian coordinates for both the phasorial measurements and the state vector. Each time that supervisory control and data acquisition measurements are updated, a nonlinear state estimator runs using asynchronously gathered measurements and a limited number of synchronized measurements. In between supervisory control and data acquisition scans, each time that phasor measurements are refreshed, a linear state estimation is executed. The proposed scheme processes separately the conventional and the phasorial measurements. The method is validated by simulation results on the IEEE 14 and 118 bus benchmark systems.
The most crucial functions of modern power systems are monitoring and control. These tasks can be... more The most crucial functions of modern power systems are monitoring and control. These tasks can be efficiently accomplished using synchronized phasor measurement units (PMUs) which are extremely accurate devices installed at substations providing measurements of the voltage phasor at the installation bus and the current phasors in the branches originated from that bus. Worldwide many utilities have scheduled the installation of a large number of PMUs in the near future, rendering their optimal deployment at substations a problem of major significance. This paper proposes a semidefinite programming algorithm for optimal PMU placement at substations including also the transformer tap settings as state variables, by adding a fictitious bus and branch for each tap-changing transformer. Simulation results for the IEEE 14-bus and 30-bus test systems prove the effectiveness of the proposed algorithm.
Synchrophasor measurement technology has been rapidly deployed in modern power systems and in con... more Synchrophasor measurement technology has been rapidly deployed in modern power systems and in conjunction with information and communication technology enables situational awareness, one of the key steps for the development of smart grids. Smart grid monitoring and control are crucial functions for the satisfaction of consumer energy demand. The developed applications to achieve these tasks are based on complicated models and powerful mathematical programming solving tools. This paper presents the synchrophasor measurement technology background, emphasizing in power grid applications using semidefinite programming, a major subclass of conic linear programming. Illustrative test cases from different research topics are analytically described and simulated to validate the effectiveness of the proposed techniques.
IEEE Transactions on Power Delivery, 2019
IEEE Systems Journal, Sep 1, 2018
This paper presents an advanced method for joint placement of unsynchronized conventional measure... more This paper presents an advanced method for joint placement of unsynchronized conventional measurements and synchronized phasorial measurements in unobservable power systems. Observability checking and determination of maximal observable islands are carried out either by a numerical procedure using the triangular factors of the gain matrix or by a binary semidefinite programming (BSDP) method that minimizes a linear objective function subject to linear matrix inequality constraints associated with the gain matrix representing the entire (unreduced) network and the existing measurement system. The minimal set of single measurements or groups of measurements that make the system observable is also determined by a BSDP-based placement algorithm which is applied on a reduced network and measurement set, whose size is governed by the rank deficiency of the Jacobian matrix resulting from the configuration of the existing conventional and phasorial measurements. The BSDP optimization problem is solved using an outer approximation scheme based on binary integer linear programming. Simulations are carried out on different IEEE benchmark systems to confirm the efficiency and effectiveness of the proposed approach.
Electric Power Systems Research, Dec 1, 2020
The accuracy and integrity of state estimators are perniciously influenced by false data injectio... more The accuracy and integrity of state estimators are perniciously influenced by false data injection attacks (FDIAs) trying to manipulate the values of a subset of measurements without being detected by the underlying bad data processing scheme. In the framework of vulnerability analysis, we examine FDIAs against a PMU linear state estimator based on Cartesian formulation in the presence of zero injection buses, under the assumption that the attacker would most likely try to corrupt as few measurements as possible. Exact and relaxed complementarity reformulations to cardinality minimization are proposed in order to compute minimal sets of measurements whose values need to be maliciously modified for successful FDIAs. The performance of the proposed approaches is demonstrated with experimental evaluations over IEEE benchmark systems.
Energies, Apr 28, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This paper proposes an optimization method to optimally place meters in transmission systems aimi... more This paper proposes an optimization method to optimally place meters in transmission systems aiming at enhanced state estimation accuracy and minimized number of installed meters. Two optimization criteria are considered for the meter placement formulation, both yielding objective functions with integer decision variables subject to linear matrix inequality constraints. An efficient mixed integer semidefinite programming algorithm is used for solving the problem. The validity of the proposed method is evaluated via numerical simulations on the IEEE 14- and 30- bus benchmark systems.
This paper presents a unified binary semidefinite programming (BSDP) model with binary decision v... more This paper presents a unified binary semidefinite programming (BSDP) model with binary decision variables, for optimal placement of phasor measurement units, considering the impact of pre-existing conventional and synchronized phasor measurements as well as the limited channel capacity of phasor measurement units. A linear objective function is minimized subject to linear matrix inequality observability constraints. The developed method is solved with an outer approximation scheme based on binary integer linear programming. The proposed method is illustrated using the IEEE 14-bus test system. Simulations are conducted on the IEEE 57-bus and 118-bus test systems to prove the validity of the proposed method.
Atmosphere, Feb 16, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
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Papers by Nikolaos Manousakis