A novel load shedding methodology to mitigate voltage instability in power system

Aim. A novel technique for detecting imminent voltage instability is proposed in this paper, accompanied by a novel load shedding approach to protect the system from voltage instability. Methodology. The proposed methodology utilizes the computation of nodal reactive power loss to voltage sensitivities with load increments in the system. Originality. The nodal reactive power loss to voltage sensitivity is a novel computation and is explored to detect the likelihood of voltage instability in this work. Results. If the system is experiencing an unprecedented load growth and if all the measures reach their limits, then load shedding is the last resort to safeguard the system against instability. The sudden change in nodal reactive power loss to voltage sensitivities is utilized to devise the quantity of load to be cut in the system. Practical value. The time-based simulations performed in New England 39 bus test system (NE-39 bus), the simulated results show that nodal reactive power loss to voltage sensitivities can be used as a trusted indicator for early diagnosing of menacing voltage instability and the timely implementation of load shedding developed from nodal reactive power loss to voltage sensitivities on the system ensures voltage stability.Мета. У статті пропонується новий метод виявлення навислої нестабільності напруги, що супроводжується новим підходом до скидання навантаження для захисту системи від нестабільності напруги. Методологія. У запропонованій методиці використовується розрахунок вузлових втрат реактивної потужності залежно від чутливості до напруги при збільшенні навантаження у системі. Оригінальність. У цій роботі вузлові втрати реактивної потужності залежно від чутливості до напруги являють собою новий розрахунок і досліджуються визначення ймовірності нестабільності напруги. Результати. Якщо система відчуває безпрецедентне зростання навантаження і всі заходи досягають меж своїх можливостей, скидання навантаження є останнім засобом захисту від нестабільності. Раптова зміна вузлових втрат реактивної потужності, залежно від чутливості до напруги, використовується для визначення величини навантаження, яка повинна бути відсічена в системі. Практична цінність. Моделювання, засноване на часі, виконане в тестовій системі шини New England 39 (шина NE-39), та результати моделювання показують, що залежність вузлових втрат реактивної потужності від чутливості до напруги може використовуватися як надійний індикатор для ранньої діагностики загрозливої нестабільності напруги та своєчасного впровадження скидання навантаження, що виникає внаслідок втрати реактивної потужності у вузлах, до чутливості системи до напруги,а забезпечує стабільність напруги

Wide-Area Time-Synchronized Closed-Loop Control of Power Systems And Decentralized Active Distribution Networks

The rapidly expanding power system grid infrastructure and the need to reduce the occurrence of major blackouts and prevention or hardening of systems against cyber-attacks, have led to increased interest in the improved resilience of the electrical grid. Distributed and decentralized control have been widely applied to computer science research. However, for power system applications, the real-time application of decentralized and distributed control algorithms introduce several challenges. In this dissertation, new algorithms and methods for decentralized control, protection and energy management of Wide Area Monitoring, Protection and Control (WAMPAC) and the Active Distribution Network (ADN) are developed to improve the resiliency of the power system. To evaluate the findings of this dissertation, a laboratory-scale integrated Wide WAMPAC and ADN control platform was designed and implemented. The developed platform consists of phasor measurement units (PMU), intelligent electronic devices (IED) and programmable logic controllers (PLC). On top of the designed hardware control platform, a multi-agent cyber-physical interoperability viii framework was developed for real-time verification of the developed decentralized and distributed algorithms using local wireless and Internet-based cloud communication. A novel real-time multiagent system interoperability testbed was developed to enable utility independent private microgrids standardized interoperability framework and define behavioral models for expandability and plug-and-play operation. The state-of-theart power system multiagent framework is improved by providing specific attributes and a deliberative behavior modeling capability. The proposed multi-agent framework is validated in a laboratory based testbed involving developed intelligent electronic device prototypes and actual microgrid setups. Experimental results are demonstrated for both decentralized and distributed control approaches. A new adaptive real-time protection and remedial action scheme (RAS) method using agent-based distributed communication was developed for autonomous hybrid AC/DC microgrids to increase resiliency and continuous operability after fault conditions. Unlike the conventional consecutive time delay-based overcurrent protection schemes, the developed technique defines a selectivity mechanism considering the RAS of the microgrid after fault instant based on feeder characteristics and the location of the IEDs. The experimental results showed a significant improvement in terms of resiliency of microgrids through protection using agent-based distributed communication

Hardware implementation of an automatic adaptive centralized under frequency load shedding

Due to the shortcomings of the conventional Under Frequency Load Shedding UFLS, most researches develop an adaptive UFLS schemes. With the aid of new technology hardware that enables the implementation of Wide Area Monitoring Protection and Control (WAMPC) application, this gives the opportunity for using industrial grade hardware to implement, evaluate these schemes and, therefore, to validate the recent research findings for industrial use. This study implements a centralized adaptive UFLS algorithm using industry grade hardware such as Phasor Measurement Units (PMUs), Synchrophasor Vector Processor (SVP) that resembles real time system operation. The study examines disturbance effects on the frequency at different disturbance locations. Each time the algorithm decisions are able to restore system frequency to a safe level and improve voltage level at the load buses. Besides, the algorithm is able to distribute the amount of power to be shed differently with the disturbance locations

A Review on Equipment Protection and System Protection Relay in Power System

Power system equipment is configured and connected together with multiple voltage levels in existing electrical power system. There are varieties of electrical equipment obtainable in the power system predominantly from generation side up to the distribution side. Consequently, appropriate protections must be apt to prevent inessential disturbances that lead to voltage instability, voltage collapse and sooner a total blackout took place in the power system. The understanding of each component on the system protection is critical. This is due to any abnormal condition and failure can be analyzed and solved effectively due to the rapid changing and development on the power system network. Therefore, the enhancement of power quality can be achieved by sheltering the equipment with protection relay in power system. Moreover, the design of a systematic network is crucial for the system protection itself. Several types of protective equipment and protection techniques are taken into consideration in this paper. Hence, the existing accessible types and methods of system protection in the power system network are reviewed

Adaptive underfrequency load shedding based on real time simulation

Conventional Underfrequency Load Shedding (UFLS) is used to balance generation and load when underfrequency conditions occur. It sheds a fixed, predetermined amount of load irrespective of disturbance location. Several adaptive UFLS schemes are proposed in the literature. Recent research discussed utilizing synchrophasor messages to implement adaptive UFLS but these studies have been using virtual PMUs. Of late, hardware implementations for adaptive UFLS scheme using actual Phasor Measurement Units (PMUs) are reported but also these studies are based on small power systems. This study presents hardware implementation of adaptive UFLS based on real time simulation of IEEE39-bus system. The simulation tool used was OPAL-RT eMEGAsim real time digital simulator. To emulate the actual environment where the scheme could be used, a complete phasor network setup is established using actual devices, such as high accuracy Global Positioning System (GPS) clocks, PMUs and Synchrophasor Vector Processor (SVP). The results obtained show that the adaptive UFLS scheme restored the frequency and curtailed the load based on voltage sag. Furthermore, the results are compared with conventional UFLS scheme

Security of electric power systems : cascading outage analysis, interdiction model and resilience to natural disasters

textSecure electric power system operation is key to social warfare. However, recent years have seen numerous natural disasters and terrorist attacks that threat the grid security. This dissertation summarizes the efforts to develop a model to analyze cascading outages, an interdiction model to analyze worst-case attacks on power grids, and research on grid resilience to natural disasters. The developed cascading outage analysis model uses outage checkers to systematically simulate the system behavior after an initial disturbance, and calculate the potential cascading outage path and electric load shedding. The new interdiction model combines the previously developed medium-term attack-defense model with the short-term cascading outage analysis model to find worst-case terrorist attack. The dissertation also reviews the research on power grid resilience to natural disaster, and develops a framework to simulate the impacts of hurricanes.Electrical and Computer Engineerin

Scenarios for the development of smart grids in the UK: literature review

Smart grids are expected to play a central role in any transition to a low-carbon energy future, and much research is currently underway on practically every area of smart grids. However, it is evident that even basic aspects such as theoretical and operational definitions, are yet to be agreed upon and be clearly defined. Some aspects (efficient management of supply, including intermittent supply, two-way communication between the producer and user of electricity, use of IT technology to respond to and manage demand, and ensuring safe and secure electricity distribution) are more commonly accepted than others (such as smart meters) in defining what comprises a smart grid. It is clear that smart grid developments enjoy political and financial support both at UK and EU levels, and from the majority of related industries. The reasons for this vary and include the hope that smart grids will facilitate the achievement of carbon reduction targets, create new employment opportunities, and reduce costs relevant to energy generation (fewer power stations) and distribution (fewer losses and better stability). However, smart grid development depends on additional factors, beyond the energy industry. These relate to issues of public acceptability of relevant technologies and associated risks (e.g. data safety, privacy, cyber security), pricing, competition, and regulation; implying the involvement of a wide range of players such as the industry, regulators and consumers. The above constitute a complex set of variables and actors, and interactions between them. In order to best explore ways of possible deployment of smart grids, the use of scenarios is most adequate, as they can incorporate several parameters and variables into a coherent storyline. Scenarios have been previously used in the context of smart grids, but have traditionally focused on factors such as economic growth or policy evolution. Important additional socio-technical aspects of smart grids emerge from the literature review in this report and therefore need to be incorporated in our scenarios. These can be grouped into four (interlinked) main categories: supply side aspects, demand side aspects, policy and regulation, and technical aspects.