Application of Advanced Early Warning Systems with Adaptive Protection

This project developed and field-tested two methods of Adaptive Protection systems utilizing synchrophasor data. One method detects conditions of system stress that can lead to unintended relay operation, and initiates a supervisory signal to modify relay response in real time to avoid false trips. The second method detects the possibility of false trips of impedance relays as stable system swings “encroach” on the relays’ impedance zones, and produces an early warning so that relay engineers can re-evaluate relay settings. In addition, real-time synchrophasor data produced by this project was used to develop advanced visualization techniques for display of synchrophasor data to utility operators and engineers

Low-cost implementation and characterization of an active phasor data concentrator

The main components of an advanced measurement system based on synchrophasor technology for the monitoring of power systems are the phasor measurement unit (PMU), which represents the ‘sensor’, and the phasor data concentrator (PDC), which collects the data forwarded by PMUs installed on the field. For the purpose of extending the benefit of synchrophasor technology from transmission grids to distribution networks, different projects are seeking to use low-cost platforms to design devices with PMU functionalities. In this perspective, in order to achieve a complete synchrophasor-based measurement architecture based on low-cost technologies, this work presents a PDC design based on a low-cost platform. Despite the simplicity of the considered hardware, advanced PDC functionalities and innovative control logics are implemented in the prototype. The proposed device is characterised by several experimental tests aimed at assessing its performance in terms of both time synchronisation and capability of managing several PMU data streams. The feasibility of some additional functionalities and control logics is evaluated in the context of different possible scenarios

Design and Implementation of a Centralized Disturbance Detection System for Smart Microgrids

RÉSUMÉ L’excursion de fréquence et de tension sont parmi les défis nombreux qui se posent aux microréseaux. La détection des perturbations peut être effectuée par le système de surveillance centralisé de micro-réseaux qui utilise des données de synchrophasor rapportées à partir de différents noeuds. Les réseaux de communication de synchrophasor présentent des retards et des Pertes de paquets qui peuvent détériorer l’intégrité des données et donc compromettre la fiabilité des systèmes de surveillance et de contrôle des micro-réseaux intelligents. Ce mémoire présente un nouveau concentrateur de données de vecteurs de phase avancé (APDC) capable de contrer les manques de la communication et d’améliorer la qualité des ressources de la production décentralisée (DER) dans les micro-réseaux. L’APDC proposé utilise un système de compensation adaptatif pour obtenir une estimation efficace des éléments de données manquants. L’estimateur adaptatif utilise le taux de changement d’éléments de données pour choisir entre l’estimateur LMMSE et un estimateur basé sur les dérivés pour prédire les valeurs futures des éléments de données. Si, à un instant donné, les éléments de données synchrophasors de certaines unités de mesure de phasor (PMU) manquent, les valeurs estimées sont utilisées pour compenser les données manquantes. En outre, une unité de surveillance est proposée pour détecter de manière fiable les excursions en fréquence et identifier les DERs affectés par les îlotages. L’unité de surveillance utilise un algorithme de détection centralisé élaboré qui traite les données de fréquence pour distinguer entre l’îlotage possible des DERs et les perturbations du réseau de distribution. L’APDC proposé est développé sur la plate-forme OpenPDC en temps réel et sa performance est évaluée à l’aide d’une configuration expérimentale comprenant trois PMUs, un réseau de télécommunications, des interrupteurs, et un concentrateur de données de vecteurs de phase classique (PDC). Les résultats expérimentaux confirment une intégrité des données de haut niveau dans les conditions normales et perturbées des micro- réseaux. Des études sur l’effet du bruit de mesure montrent que l’APDC proposé est même efficace en présence de bruits sévères. De plus, une détection rapide et fiable des événements d’îlotage est obtenue en raison de l’amélioration considérable du temps de détection même en cas de pertes de données sévères et de bruit de mesure. Enfin, la performance de l’APDC proposé est comparée à une méthode d’estimation existante. Les résultats montrent l’avantage important de l’APDC, en particulier dans des conditions perturbées.----------ABSTRACT Microgrids are subject to various disturbances such as voltage transients and frequency excursions. Disturbance detection can be performed by a microgrid centralized monitoring system that employs synchrophasor data reported from different nodes within the microgrid. Synchrophasor communication networks exhibit delays and packet dropout that can undermine the data integrity and hence compromise the reliability of the monitoring and control systems of the smart microgrids. In this thesis, an advanced phasor data concentrators (APDC) is proposed that is capable of counteracting the communication impairments and improving the quality of monitoring of distributed energy resources (DERs) in microgrids. The proposed APDC utilizes an adaptive compensation scheme to achieve an efficient estimate of missing data elements. The adaptive estimator employs the rate of change of data elements to choose between the vector linear minimum mean square error (LMMSE) and the derivative-based estimators to predict the future values of data elements. Whenever the synchrophasor data elements of some phasor measurement units (PMU) are missing, the estimated values are used to compensate for the missing data. Moreover, a monitoring unit is proposed to reliably detect frequency excursions and identify the DERs affected by islanding events. The monitoring unit utilizes an elaborate centralized detection algorithm that processes frequency data to distinguish between possible islanding of DERs and disturbances occurred within the host grid. The proposed APDC is developed on a real-time OpenPDC platform and its performance is evaluated using an experimental setup including three PMUs, communication links, switches, and a conventional phasor data concentrator (PDC). The experimental results confirm a high-level data integrity under both normal and disturbed conditions. Studies on the effect of measurement noise show that the proposed APDC is even efficient in the presence of noise. Moreover, fast and reliable detection of islanding events is achieved even under severe data losses and measurement noise. Finally, the performance of the proposed APDC is compared with a recently proposed estimation method that shows the significant advantage of the APDC, especially under disturbed conditions

Measurement Platform for Latency Characterization of Wide Area Monitoring, Protection and Control Systems

Wide area monitoring, protection and control (WAMPAC) systems have emerged as a critical technology to improve the reliability, resilience, and stability of modern power grids. They are based on phasor measurement unit (PMU) technology and synchronized monitoring on a wide area. Since these systems are required to make rapid decisions and control actions on the grid, they are characterized by stringent time constraints. For this reason, the latency of WAMPAC systems needs to be appropriately assessed. Following this necessity, this article presents the design and implementation of a measurement platform that allows latency characterization of different types of WAMPAC systems in several operating conditions. The proposed WAMPAC Characterizer has been metrologically characterized through a WAMPAC Emulator and then used to measure the latency of a WAMPAC system based on an open-source platform frequently used by transmission system operators (TSOs) for the implementation of their PMU-based wide area systems

Architecture and Experimental Validation of a Low-Latency Phasor Data Concentrator

The paper presents the design principles of a Phasor Data Concentrator (PDC) that implements both the absolute and relative time data pushing logics together with a third one that aims at minimizing the latency introduced by the PDC without increasing the data incompleteness, as suggested in the IEEE Guide C37.244-2013. The performance of the aforementioned logics are assessed and compared in terms of reliability, determinism and reduction of the overall latency in two real Phasor Measurement Unit (PMU) installations adopting different telecom infrastructures. The first one is based on optical fiber links that transmit synchrophasor data measured by 15 PMUs installed in the sub-transmission network of the city of Lausanne, Switzerland. The second one adopts a 4G LTE wireless infrastructure to support the data streaming of 10 PMUs installed in a distribution network supplying the city of Huissen, in the Netherlands. The experimental results show that the proposed logic is characterized by the lowest latency, whereas the absolute time logic better mitigates the synchrophasor data latency variations

Novel performance evaluation of information and communication technologies to enable wide area monitoring systems for enhanced transmission network operation

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.The penetration of renewable energy sources has increased significantly in recent years due to the ongoing depletion of conventional resources and the transition to a low carbon energy system. Renewable energy sources such as wind energy are highly intermittent and unpredictable in nature, which makes the operation of the power grid more dynamic and therefore more complex. In order to operate the power system reliably under such conditions, Phasor Measurement Units (PMUs) through the use of satellite technology can offer a state-of-the-art Wide Area Monitoring System (WAMS) for improving power system monitoring, control and protection. They can improve the operation by providing highly precise and synchronised measurements near to real-time with higher frequency and accuracy. In order to achieve such objectives, a high-speed and reliable communications infrastructure is required to transfer time-critical PMU data from remote locations to the control centre. The signals measured by PMUs are transmitted across Local and Wide Area Networks, where they may encounter excessive delays. Signal delays can have a disruptive effect and make applications at best inefficient and at worse ineffective. The main research contribution of this thesis is the performance evaluation of communication infrastructures for WAMS. The evaluation begins from inside substations and continues over wide areas from substations to control centre. Through laboratory-based investigations and simulations, the performance of communications infrastructure in a typical power system substation has been analysed. In addition, the performance evaluation of WAMS communications infrastructure has been presented. In the modelling and analysis, an existing WAMS as installed on the GB transmission system has been considered. The actual PMU packets as received at the Phasor Data Concentrator (PDC) were captured for latency analysis. A novel algorithmic procedure has been developed and implemented to automate the large-scale latency calculations. Furthermore, the internal delays of PMUs have been investigated, determined and analysed. Subsequently, the WAMS has been simulated and detailed comparisons have been performed between the simulated model results and WAMS performance data captured from the actual WAMS. The validated WAMS model has been used for analysing possible future developments as well as to test newly proposed mechanisms, protocols, etc. in order to improve the communications infrastructure performance

Viiveiden vaikutus sähkömekaanisten heilahtelujen laajan alueen vaimennussäätöön

In this thesis the effects of delays on the wide-area damping control of electromechanical oscillations were studied. The research goals were two fold: to identify and define the delay sources in phasor measurement based (PMU) wide-area measurement systems for power systems, and to study the effects of delays on wide-area damping control using power system simulations as a research tool. The implementation the delays into a pre-existing power system simulation program as also a part of this work. The thesis shows and identifies the delays components and their properties in the wide-area measurement systems. It gives a survey on the reports of real delays observed in wide-area measurement systems worldwide. The simulation results show that delay has an impact on the damping control. Power system have a delay margin they are able to tolerate before turning unstable. Additionally, latency changes the properties of the electromechanical oscillations.Tässä diplomityössä tutkittiin viiveiden vaikutusta sähkömekaanisten heilahtelujen vaimennussäätöön. Työ oli karkeasti jaettavissa kahteen erilliseen osaan. Ensimmäinen osa oli voimajärjestelmien PMU-pohjaisten laajan alueen mittaus- ja ohjausjärjestelmien viivelähteiden löytäminen, tunnistaminen ja luokittelu. Toinen osa oli viiveiden vaikutusten tutkiminen laajan alueen heilahtelusäätöön käyttäen voimajärjestelmäsimulointia tutkimuksen työkaluna. Työn toteutus sisälsi viiveellistenmittauksien ja ohjauksien toteuttamisen valmiina olevaan simulaatio-ohjelmaan. Työ näyttää laajan alueen mittaus- ja ohjausjärjestelmien viivekomponentittien ominaisuudet ja vaikutuksen viiveketjuun sekä millaisia lukemia on raportoitu käytössä olevista järjestelmistä ympäri maailman. Työn viivesimulaatiot osoittavat, että viiveillä on merkitys sähkömekaanisten heilahtelujen vaimennussäätöön. Viiveellinen säätö muuttaa sähkömekaanisten heilahtelujen ominaisuuksia ja osoittaa, että voimajärjestelmillä on niille ominainen viiveen sietokyky

Real-Time State Estimation of the EPFL-Campus Medium-Voltage Grid by Using PMUs

We describe the real-time monitoring infrastructure of the smart-grid pilot on the EPFL campus. We experimentally validate the concept of a real-time state-estimation for a 20 kV active distribution network. We designed and put into operation the whole infrastructure composed by the following main elements: (1) dedicated PMUs connected on the medium-voltage side of the network secondary substations by means of specific current/voltage transducers; (2) a dedicated communication network engineered to support stringent time limits and (3) an innovative state estimation process for real-time monitoring that incorporates phasor-data concentration and state estimation processes. Special care was taken to make the whole chain resilient to cyber-attacks, equipment failures and power outages. The achieved latency is within 65ms. The refresh rate of the estimated state is 20ms. The real-time visualization of the state estimator output is made publicly available, as well as the historical data (PMU measurements and estimated states). To the best of our knowledge, the work presented here is the first operational system that provides low-latency real-time state estimation by using PMU measurements of a real active distribution network