8 research outputs found
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An Assessment of PIER Electric Grid Research 2003-2014 White Paper
This white paper describes the circumstances in California around the turn of the 21st century that led the California Energy Commission (CEC) to direct additional Public Interest Energy Research funds to address critical electric grid issues, especially those arising from integrating high penetrations of variable renewable generation with the electric grid. It contains an assessment of the beneficial science and technology advances of the resultant portfolio of electric grid research projects administered under the direction of the CEC by a competitively selected contractor, the University of California鈥檚 California Institute for Energy and the Environment, from 2003-2014
Modeling and Control of Power Electronics Interfaced Load for Transmission Power Network Analysis
The penetration level of power electronics (PE) interfaced loads has been gradually increasing in recent years. It is beneficial to equip the electric load with a PE interface since it allows for more advanced control of the load performance. Furthermore, the increasing penetration of PE interfaced loads will bring both challenges and opportunities to power network resilience and reliability.
However, the lack of modeling and control design for PE interfaced load units in the transmission-level power network analysis, especially for these high-penetrated high-power-rating load applications, limits the accuracy of evaluating the dynamic performance and stability status of the power network. Additionally, the complex configuration and high bandwidth dynamic performance of the PE interfaced load computationally prohibit the model development in transient stability (TS) simulation programs.
Therefore, the dynamic PE interfaced load model can be characterized considering the following aspects: 1) Utilize the real-time experimental platform to represent the PE load dynamic performance since the power testbed can reflect the power grid operation with more robustness. 2) Adapt the simplified PE-based model to TS simulation tools, which focus on grid electromechanical transients and oscillations between 0.1 and 3 Hz.
Research of the PE interfaced load towards its modeling and control design in different simulation environments and the flexible contribution to the grid operation has been conducted. First, the variable speed drive (VSD) based motor load is studied as a typical PE interfaced load, which can actively interact with power grid operation. The model of VSD load is introduced and applied to the power emulator for the multi-converter-based hardware testbed (HTB) in the Center of Ultra-wide-area Resilient Electric Energy Transmission Network (CURENT). Second, the aggregated performance of multiple VSD load units with grid frequency support function is characterized. Third, the fast electric vehicle (EV) charging unit is studied as a typical PE interfaced load with high power consumption. The generic model of EV charger load is developed based on the detailed switching model. The accuracy of the proposed EV charger load TS model has been verified by comparing it to simulation results of the equivalent electromagnetic (EMT) model
Modelling and Co-simulation of Multi-Energy Systems: Distributed Software Methods and Platforms
L'abstract 猫 presente nell'allegato / the abstract is in the attachmen
Ontologies for the Interoperability of Heterogeneous Multi-Agent Systems in the scope of Energy and Power Systems
Tesis por compendio de publicaciones[ES]El sector el茅ctrico, tradicionalmente dirigido por monopolios y poderosas
empresas de servicios p煤blicos, ha experimentado cambios significativos en las
煤ltimas d茅cadas. Los avances m谩s notables son una mayor penetraci贸n de las
fuentes de energ铆a renovable (RES por sus siglas en ingl茅s) y la generaci贸n
distribuida, que han llevado a la adopci贸n del paradigma de las redes inteligentes
(SG por sus siglas en ingl茅s) y a la introducci贸n de enfoques competitivos en los
mercados de electricidad (EMs por sus siglas en ingl茅s) mayoristas y algunos
minoristas. Las SG emergieron r谩pidamente de un concepto ampliamente
aceptado en la realidad. La intermitencia de las fuentes de energ铆a renovable y su
integraci贸n a gran escala plantea nuevas limitaciones y desaf铆os que afectan en
gran medida las operaciones de los EMs. El desafiante entorno de los sistemas de
potencia y energ铆a (PES por sus siglas en ingl茅s) refuerza la necesidad de
estudiar, experimentar y validar operaciones e interacciones competitivas,
din谩micas y complejas. En este contexto, la simulaci贸n, el apoyo a la toma de
decisiones, y las herramientas de gesti贸n inteligente, se vuelven imprescindibles
para estudiar los diferentes mecanismos del mercado y las relaciones entre los
actores involucrados. Para ello, la nueva generaci贸n de herramientas debe ser
capaz de hacer frente a la r谩pida evoluci贸n de los PES, proporcionando a los
participantes los medios adecuados para adaptarse, abordando nuevos modelos
y limitaciones, y su compleja relaci贸n con los desarrollos tecnol贸gicos y de
negocios.
Las plataformas basadas en m煤ltiples agentes son particularmente
adecuadas para analizar interacciones complejas en sistemas din谩micos, como
PES, debido a su naturaleza distribuida e independiente. La descomposici贸n de
tareas complejas en asignaciones simples y la f谩cil inclusi贸n de nuevos datos y
modelos de negocio, restricciones, tipos de actores y operadores, y sus
interacciones, son algunas de las principales ventajas de los enfoques basados en
agentes. En este dominio, han surgido varias herramientas de modelado para
simular, estudiar y resolver problemas de subdominios espec铆ficos de PES. Sin
embargo, existe una limitaci贸n generalizada referida a la importante falta de
interoperabilidad entre sistemas heterog茅neos, que impide abordar el problema
de manera global, considerando todas las interrelaciones relevantes existentes.
Esto es esencial para que los jugadores puedan aprovechar al m谩ximo las
oportunidades en evoluci贸n. Por lo tanto, para lograr un marco tan completo aprovechando las herramientas existentes que permiten el estudio de partes
espec铆ficas del problema global, se requiere la interoperabilidad entre estos
sistemas.
Las ontolog铆as facilitan la interoperabilidad entre sistemas heterog茅neos al
dar un significado sem谩ntico a la informaci贸n intercambiada entre las distintas
partes. La ventaja radica en el hecho de que todos los involucrados en un dominio
particular los conocen, comprenden y est谩n de acuerdo con la conceptualizaci贸n
all铆 definida. Existen, en la literatura, varias propuestas para el uso de ontolog铆as
dentro de PES, fomentando su reutilizaci贸n y extensi贸n. Sin embargo, la mayor铆a
de las ontolog铆as se centran en un escenario de aplicaci贸n espec铆fico o en una
abstracci贸n de alto nivel de un subdominio de los PES. Adem谩s, existe una
considerable heterogeneidad entre estos modelos, lo que complica su integraci贸n
y adopci贸n. Es fundamental desarrollar ontolog铆as que representen distintas
fuentes de conocimiento para facilitar las interacciones entre entidades de
diferente naturaleza, promoviendo la interoperabilidad entre sistemas
heterog茅neos basados en agentes que permitan resolver problemas espec铆ficos de
PES.
Estas brechas motivan el desarrollo del trabajo de investigaci贸n de este
doctorado, que surge para brindar una soluci贸n a la interoperabilidad de
sistemas heterog茅neos dentro de los PES. Las diversas aportaciones de este
trabajo dan como resultado una sociedad de sistemas multi-agente (MAS por sus
siglas en ingl茅s) para la simulaci贸n, estudio, soporte de decisiones, operaci贸n y
gesti贸n inteligente de PES. Esta sociedad de MAS aborda los PES desde el EM
mayorista hasta el SG y la eficiencia energ茅tica del consumidor, aprovechando
las herramientas de simulaci贸n y apoyo a la toma de decisiones existentes,
complementadas con las desarrolladas recientemente, asegurando la
interoperabilidad entre ellas. Utiliza ontolog铆as para la representaci贸n del
conocimiento en un vocabulario com煤n, lo que facilita la interoperabilidad entre
los distintos sistemas. Adem谩s, el uso de ontolog铆as y tecnolog铆as de web
sem谩ntica permite el desarrollo de herramientas agn贸sticas de modelos para una
adaptaci贸n flexible a nuevas reglas y restricciones, promoviendo el razonamiento
sem谩ntico para sistemas sensibles al contexto
Secure Control and Operation of Energy Cyber-Physical Systems Through Intelligent Agents
The operation of the smart grid is expected to be heavily reliant on microprocessor-based control. Thus, there is a strong need for interoperability standards to address the heterogeneous nature of the data in the smart grid. In this research, we analyzed in detail the security threats of the Generic Object Oriented Substation Events (GOOSE) and Sampled Measured Values (SMV) protocol mappings of the IEC 61850 data modeling standard, which is the most widely industry-accepted standard for power system automation and control. We found that there is a strong need for security solutions that are capable of defending the grid against cyber-attacks, minimizing the damage in case a cyber-incident occurs, and restoring services within minimal time.
To address these risks, we focused on correlating cyber security algorithms with physical characteristics of the power system by developing intelligent agents that use this knowledge as an important second line of defense in detecting malicious activity. This will complement the cyber security methods, including encryption and authentication. Firstly, we developed a physical-model-checking algorithm, which uses artificial neural networks to identify switching-related attacks on power systems based on load flow characteristics.
Secondly, the feasibility of using neural network forecasters to detect spoofed sampled values was investigated. We showed that although such forecasters have high spoofed-data-detection accuracy, they are prone to the accumulation of forecasting error. In this research, we proposed an algorithm to detect the accumulation of the forecasting error based on lightweight statistical indicators. The effectiveness of the proposed algorithms was experimentally verified on the Smart Grid testbed at FIU. The test results showed that the proposed techniques have a minimal detection latency, in the range of microseconds.
Also, in this research we developed a network-in-the-loop co-simulation platform that seamlessly integrates the components of the smart grid together, especially since they are governed by different regulations and owned by different entities. Power system simulation software, microcontrollers, and a real communication infrastructure were combined together to provide a cohesive smart grid platform. A data-centric communication scheme was selected to provide an interoperability layer between multi-vendor devices, software packages, and to bridge different protocols together
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Smart Grid Technologies and Implementations
Smart grid has been advocated in both developing and developed countries in many years to deal with large amount of energy deficit and air pollutions. However, many literatures talked about some specific technologies and implementations, few of them could give a clear picture on the smart grid implementations in a macro scale like what is the main consideration for the smart grid implementations, how to examine the power system operation with communication network deployment, how to determine the optimal technology scheme with consideration of economic and political constraints, and so on. Governments and related institutions are keen to evaluate the cost and benefit of new technologies or mechanisms in a scientific way rather than making decision blindly. Decision Support System, which is an information system based on interactive computers to support decision making in planning, management, operations for evaluating technologies, is an essential tool to provide decision makers with powerful scientific evidence.
The objective of the thesis is to identify the data and information processing technologies and mechanisms which will enable the further development of decision support systems that can be used to evaluate the indices for smart grid technology investment in the future.
First of all, the thesis introduces the smart grid and its features and technologies in order to clarify the benefits can be obtained from smart grid deployment in many aspects such as economics, environment, reliability, efficiency, security and safety.
Besides, it is necessary to understand power system business and operation scenarios which may affect the communication network model. This thesis, for the first time, will give detailed requirements for smart grid simulation according to the power system business and operation.
In addition, state of art monitoring system and communication system involved in smart grid for better demand side management will be reviewed in order to find out their impacts reflecting to the power systems. The methods and algorithms applied to the smart grid monitoring, communication technologies for smart grid are summarized and the monitoring systems are compared with each other to see the merits and drawbacks in each type of the monitoring system.
In smart grid environment, large number of data are need to be processed and useful information are required to be abstracted for further operation in power systems. Machine learning is a useful tool for data mining and prediction. One of the typical machine learning artificial algorithms, artificial neural network (ANN) for load forecasting in large power system is proposed in this thesis and different learning methods of back-propagation, Quasi-Newton and Levenberg-Marquardt, are compared with each other to seek the best result in load forecasting.
Bad load forecasting may leads to demand and generation mismatch, which could cause blackout in power systems. Load shedding schemes are powerful defender for power system from collapsing and keep the grid in integral to a maximum extent. A lesson learned from India blackout in July 2012 is analyzed and recommendations on preventing grid from blackout are given in this work. Also, a new load shedding schemes for an isolated system is proposed in this thesis to take full advantage from information sharing and communication network deployment in smart grid.
Lastly, the new trend of decision support system (DSS) for smart grid implementation is summarized and reliability index and stability scenarios for cost benefit analysis are under DSS consideration. Many countries and organizations are setting renewable penetration goals when planning the contribution to reduce the greenhouse gas emission in the future 10 or 20 years. For instance, UK government is expecting to produce 27% of renewable energies EU-wide before 2030. Some simulations have been carried out to demonstrate the physical insight of a power system operation with renewable energy integration and to study the non-dispatchable energy source penetration level. Meanwhile, issues from power system reliability which may affect consumers are required to take into account. Reliability index of Centralized wind generations and that of distributed wind generations are compared with each other under an investment perspective