Protection Scheme for Island Operated Medium-Voltage Microgrid

2015 ◽  
Vol 10 (4) ◽  
pp. 510 ◽  
Author(s):  
Hannu Laaksonen
Keyword(s):  
Medium Voltage ◽  
Protection Scheme

scholarly journals Evaluation of Lightning Induced Voltage due to the Effect of Design Parameters on Medium Voltage Distribution Line

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
N. Rameli ◽  
M. Z. A. Ab Kadir ◽  
M. Izadi ◽  
C. Gomes ◽  
J. Jasni
Keyword(s):  
Power Line ◽  
Design Parameters ◽  
Induced Voltage ◽  
Voltage Distribution ◽  
Medium Voltage ◽  
Protection Scheme ◽  
Lightning Channel ◽  
Utility Companies ◽  
Distribution Line ◽  
Ground Conductivity

This paper investigates the effect of design parameters on the induced voltages on a distribution power line. This investigation is based on perfect ground conductivity, single stroke lightning and lightning without branches. The design of the parameters includes, d, the striking distance of the lightning, h, the height of the conductor, and r, the diameter of the conductor, all of which are elements that produce the variations in the induced voltage on a distribution power line with respect to a vertical or an inclined lightning channel. Thus, the outcome of this investigation can act as a guide for utility companies or other power engineers in order to plan an appropriate protection scheme for a distribution power line.

scholarly journals Investigating Phase Over-Current (OC) Protection in Medium-Voltage networks

2019 ◽  
Vol 4 (6) ◽  
pp. 41-49 ◽  
Author(s):  
Aniagboso John Onah
Keyword(s):  
Power System ◽  
Electric Power ◽  
Electric Power System ◽  
Normal Operation ◽  
Electrical Network ◽  
Power Circuit ◽  
Medium Voltage ◽  
Protection Scheme ◽  
Overcurrent Protection ◽  
Overcurrent Relays

Overcurrent protection is protection against excessive currents or current beyond the acceptable current rating of equipment. It generally operates instantly. Short circuit is a type of overcurrent. Magnetic circuit breakers, fuses and overcurrent relays are commonly used to provide overcurrent protection. There is always a need to protect expensive power equipment. Protective relaying is a very important part of any electric power system that comes into play during trouble, fault or abnormal condition. The purpose is to isolate unhealthy part of electrical power system while the rest continue their normal operation. The entire electric power system from source to load centers is exposed and subject to natural hazards. The effects of these hazards are capable of interrupting normal operations of the system. Since these hazards cannot be prevented, precautions are taken to minimize or eliminate their effect on the system. The relay is a basic component of any protection scheme. The information (or signals) received from the power system actuates the relay, when necessary, to perform one or more switching actions. The signals are proportional to the magnitudes and phase angles of power system voltages and currents. When the relay receives these signals, it decides to close (or open) one or more sets of normally open (or closed) contacts, and consequently, the trip coil of a circuit breaker will be energized to open the power circuit. This paper investigates over-current relay protection scheme applied to medium-voltage electrical network. Methods of current and time grading have been applied in the coordination of the overcurrent relays in a radial network. Different time/current characteristics of relays such as the normal inverse (NI), very inverse (VI), and extreme inverse (EI) have been examined in order to obtain optimum discrimination.

scholarly journals Microgrid Protection Strategy Based on the Autocorrelation of Current Envelopes Using the Squaring and Low-Pass Filtering Method

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2350 ◽  
Author(s):  
Shazia Baloch ◽  
Saeed Zaman Jamali ◽  
Khawaja Khalid Mehmood ◽  
Syed Basit Ali Bukhari ◽  
Muhammad Saeed Uz Zaman ◽  
...  
Keyword(s):  
Reactive Power ◽  
Short Circuit ◽  
Backup Protection ◽  
Medium Voltage ◽  
Protection Scheme ◽  
High Penetration ◽  
Islanded Operation ◽  
Three Phase ◽  
Low Pass ◽  
Efficient Protection

To resolve the protection issues caused by high penetration of distributed energy resources, this paper proposes an efficient protection scheme for microgrids based on the autocorrelation of three-phase current envelopes. The proposed strategy uses a squaring and low-pass filtering approach for evaluating the envelope of the current signal. Then, the variance of the autocorrelation function is used to extract the hidden information of the distorted envelope to detect the fault signatures in the microgrid. Furthermore, the reactive power is used for determining the fault direction. The performance of the proposed protection scheme was verified on a standard medium-voltage microgrid by performing simulations in the MATLAB/Simulink environment (Version: R2017b). The proposed scheme was shown to be easy to implement and have good performance under looped and radial configuration for both grid-connected and islanded operation modes. The simulation results showed that the scheme could not only detect, locate, classify, and isolate various types of short-circuit faults effectively but also provide backup protection in case of primary protection failure.

scholarly journals Efficient Protection Scheme Based on Y-Source Circuit Breaker in Bi-Directional Zones for MVDC Micro-Grids

Inventions ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 18
Author(s):  
Haider Al-khafaf ◽  
Johnson Asumadu
Keyword(s):  
Power Flow ◽  
Circuit Breaker ◽  
Magnetic Coupling ◽  
Medium Voltage ◽  
Protection Scheme ◽  
Fault Type ◽  
Source Impedance ◽  
Source Current ◽  
Efficient Protection ◽  
Micro Grids

A new bi-directional circuit breaker is presented for medium-voltage dc (MVDC) systems. The Y-source impedance network topology is used to implement the breaker. The current transfer function is derived to show the frequency response and the breaker operation with the high frequencies. Mathematical analysis is achieved with different conditions of coupling among the breaker inductors. The minimum level of the magnetic coupling is determined, which is represented by the null condition. The effect of the turns-ratio on this condition is investigated as well. The breaker is designed with two types of fault conductance slope rates. The Y-source breaker is simulated, and the results verify the breaker operation during the fault condition and the load change. The results also demonstrate the effect of the coupling level on the minimum values of the source current when the fault occurs. Based on the expected fault type in the MVDC systems, the proposed breaker is developed to interrupt the overcurrent due to any of these fault types. A protection scheme is proposed for a 12-bus, two-level micro-grid, where the Y-source breakers are used in the bi-directional zones. The results verify the ability of the breaker to conduct and interrupt the current in both directions of the power flow.

scholarly journals Micro-Grid Design and Protection System under Several Fault Conditions

2019 ◽  
Vol 8 (6) ◽  
pp. 875-880
Keyword(s):  
Fault Analysis ◽  
Environmental Benefits ◽  
Protection System ◽  
Small Scale ◽  
Photovoltaic Module ◽  
Distributed Generator ◽  
Medium Voltage ◽  
Protection Scheme ◽  
Micro Grid ◽  
Design Protection

As distributed generators and renewable energies are now becoming the fastest growing technologies in the energy industries, the technical issues and environmental aspects are to studied and examined. The large number of small scale Micro grid components with their characteristics is a vital challenge for Micro grid modelling, operation, simulation and operation. Micro-grid gives clear, economic and environmental benefits for end users, utilities, and societies. However, their implementation faces lot of challenges, such as a protection of micro-grid. Micro-grid works in two modes, grid-connected and islanded mode that operates connected with medium voltage grid or islanded from the grid with controlled coordinate manner. The major goal of this thesis is to design protection for. First, the work is done to present the detailed description of the micro grid models and lines. Then the paper will discuss the distributed generator models that have been implemented in MATLAB/Simulink including photovoltaic module, fuel cell stack system with short term storage (Li-ion battery system). Then the fault analysis is done for the whole Micro-grid, whether the micro grid is working in fault condition or not. Then Micro grid protection is done for the grid connected modes and islanding modes of Micro grid. To design the protection system for the micro grid over current relay protection scheme is used.

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