Identification and development of microgrids emergency control procedures

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

Control and operation of multiple distributed generators in a microgrid

Small sized synchronous generator based distributed generators (DG) often have low start-up times, and can serve as dispatchable generators in a microgrid environment. The advantage is that it allows the power network to operate in a true smart grid environment. The disadvantage is that such DGs typically tend to have low inertia and the prime movers driving these resources need to be controlled in real time for them to operate effectively in islanded, grid-connected modes and during transition from grid-connected mode to islanded mode and vice versa. When multiple DGs are present in the microgrid, the overall control can become complicated because of the need for sharing the resources. A smart grid environment is then necessary to control all dispersed generation sources in the microgrid. The most common control strategy adopted for multiple DGs connected to a network is droop control. Droop control ensures that the load needed to be served is shared by all the generators in the network in proportion to their generating capability. When DGs operate in a microgrid environment, there is a need for coordinated operation between the DGs, the utility grid and the loads. A MicroGrid Central Controller (MGCC) can keep track of the status from the system standpoint and command the local Microsource Controllers (MC) to ensure system stability. In various modes of operation like grid connected, islanding and during transition, the MGCC can support the MCs by giving them necessary information to contribute towards stable operation --Abstract, page iii

Design, Implementation and Evaluation of a Microgrid in Island and Grid Connected Modes with a Fuel Cell Power Source

The ability to connect a microgrid to the grid is an important step in the development and evolution of the modern power system. The principle objectives of this research are (1) to simulate a simple microgrid consisting of a PEM hydrogen fuel cell, load and connection to the grid and (2) to evaluate the resulting microgrid control system on a corresponding experimental microgrid. The microgrid simulation demonstrated that the control algorithms can operate the microgrid in both islanded (VSC with voltage and frequency regulation) and grid connected (VSC with current control for power transfer). The experimental laboratory microgrid was constructed and operated in real-time performing its black start and managed transitions between island and grid connected modes of operation. The synchronization method adjusted the island microgrid to become in phase with the grid and tracked well under steady state and load changing conditions. The synchronization process brought the island in phase with the grid within 400 ms. Passive island detection was demonstrated with the restoration to grid operation. The grid connected voltage and current THD were under 1%

Islanding Detection and Power Quality Analysis in Microgrid

芝浦工業大学2019年

Using Renewable-Based Microgrid Capabilities for Power System Restoration

Power system restoration (PSR) is a very important procedure to ensure the consumer supply. In this paper, a decentralized multi-agent system (MAS) for dealing with the microgrid restoration procedure is proposed. In this proposed method, each agent is associated to a consumer or microsource (MS) and these will communicate between each other in order to reach a common decision. The agents solve a 0/1 knapsack problem to determine the best load connection sequence during the microgrid restoration procedure. The proposed MAS is tested in two different case studies: a total blackout and a partial blackout, in which the emergency demand response programs are considered. It is developed in the Matlab/Simulink environment and is validated by performing the corresponding dynamic simulations.Power system restoration (PSR) is a very important procedure to ensure the consumer supply. In this paper, a decentralized multi-agent system (MAS) for dealing with the microgrid restoration procedure is proposed. In this proposed method, each agent is associated to a consumer or microsource (MS) and these will communicate between each other in order to reach a common decision. The agents solve a 0/1 knapsack problem to determine the best load connection sequence during the microgrid restoration procedure. The proposed MAS is tested in two different case studies: a total blackout and a partial blackout, in which the emergency demand response programs are considered. It is developed in the Matlab/Simulink environment and is validated by performing the corresponding dynamic simulations

Functional Analysis of the Microgrid Concept Applied to Case Studies of the Sundom Smart Grid

The operation of microgrids is a complex task because it involves several stakeholders and controlling a large number of different active and intelligent resources or devices. Management functions, such as frequency control or islanding, are defined in the microgrid concept, but depending on the application, some functions may not be needed. In order to analyze the required functions for network operation and visualize the interactions between the actors operating a particular microgrid, a comprehensive use case analysis is needed. This paper presents the use case modelling method applied for microgrid management from an abstract or concept level to a more practical level. By utilizing case studies, the potential entities can be detected where the development or improvement of practical solutions is necessary. The use case analysis has been conducted from top-down until test use cases by real-time simulation models. Test use cases are applied to a real distribution network model, Sundom Smart Grid, with measurement data and newly developed controllers.. The functional analysis provides valuable results when studying several microgrid functions operating in parallel and affecting each other. For example, as shown in this paper, ancillary services provided by an active customer may mean that both the active power and reactive power from customer premises are controlled at the same time by different stakeholders.© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed

A Real Multitechnology Microgrid in Venice: A Design Review

Electrical grids are evolving rapidly toward smart, self-regulating systems capable of managing distributed generation from intermittent renewable sources. Apart from hydroelectric, the large majority of them are photovoltaic (PV) systems grasping the fluctuating solar radiation and wind turbines (WT) capturing fickle wind energy, but other sources, which are at different stages of development, also generate energy with predictable or unpredictable intermittency. Several investigations have highlighted that, when power production from intermittent sources exceeds 20% of the total generation, the grid may face instabilities that can evolve into blackouts. Energy storage (ES) is a measure to balance source-load mismatches and to avoid such occurrence, but it can also provide a number of additional services which are part of the smart-grid paradigm. The operation of energy storage systems (ESSs) depends on the interface converters that manage the power flow and on the supervisors that control them according to the ESS, grid, and load features. Furthermore, the transmission system operator (TSO) may impose constraints on the ESS operation such as the obligation of contributing to primary regulation. Several numerical analyses have been developed to investigate the behavior of electrical grids provided with energy generation from renewable sources and energy storage, either islanded or connected to the national/transnational grid (macrogrid)

Modeling, Analyses and Assessment of Microgrids Considering High Renewable Energy Penetration

Microgrids are receiving attention due to the increasing need to integrate distributed generations and to ensure power quality and provide energy surety to the customers. Since renewables need to be in the mix for energy surety, a high renewable-energy penetrated microgrid is analyzed in this paper. The standard IEEE 34 bus distribution feeder is adapted and managed as a microgrid by adding distributed generation and load profiles. The 25kV system parameters are scaled down to 12kV and renewable sources including solar PV and wind turbines, an energy storage system, and a natural gas generator have been added to the 34-bus system. The distribution generations (DG) and renewables are modeled in detail using PSCAD software and practical constraints of the components are considered. The droop control and autonomous control for microgrid normal operation in islanded mode and grid-tied mode have been proposed and studied. A novel comprehensive supervisory control scheme has been defined to manage the microgrid transition from or to the bulk grid, and to minimize the transients on voltage and frequency. Detailed analyses for islanding, reconnection, and black start are presented for various conditions. The proposed control techniques accept inputs from local measurements and supervisory controls in order to manage the system voltage and frequency. The monitoring of the microgrid for measuring power quality and control requirements for DGs and storage are modeled. The power quality issues are discussed and indexes are calculated. A novel probabilistic assessment of microgrid reliability has been proposed. At last, several extended researches are presented. An experimental system has been built which includes three 250kW inverters emulating natural gas generator, energy storage, and renewable source. The simulation and experimental results are provided which verifies the analytical presentation of the hardware and control algorithms

Automation, Annunciation, and Emergency Safety Shutdown of a Laboratory Microgrid Using a Real-Time Automation Controller (RTAC)

Over the last decade, microgrid deployments throughout the world have increased. In 2019, a record number of 546 microgrids were installed in the United States [1]. This trend continues upward to combat extreme weather conditions and power shortages throughout the country. To better equip students with the necessary skillsets and knowledge to advance in the microgrid field, Cal Poly San Luis Obispo\u27s Electrical Engineering Department and the Power Energy Institute have invested resources to develop a laboratory microgrid. This thesis sets to improve the laboratory microgrid\u27s existing automation using the Schweitzer Engineering Laboratory SEL-3530 Real-time Automation Controller (RTAC). The improved automation features a new load-shedding scheme, LCD annunciator and meter panel, and emergency safety shutdown system. The load shedding scheme aims to enhance the grid\u27s frequency stability when the inverter-based power output declines. The LCD annunciator and meter panels provide real-time oversight of the microgrid operating conditions via the RTAC Human Machine Interface (HMI). The emergency safety shutdown enables prompt de-energization and complete isolation of the laboratory microgrid in hazardous conditions such as earthquake, fire, arcing, and equipment malfunction and activates an audible siren to alert help. This safety system provides safety and peace of mind for students and faculties who operate the Microgrid. Lastly, this thesis provides an operating procedure for ease of operation and experiment