scholarly journals Overcurrent and Earthfault Relay Coordination for Microgrid with Numerical Relay Features

2020 ◽  
Vol 9 (3) ◽  
pp. 1626-1630
Keyword(s):  
Distribution System ◽  
Short Circuit ◽  
Renewable Energy Sources ◽  
Short Circuit Current ◽  
Load Flow ◽  
Active Distribution System ◽  
Relay Coordination ◽  
Overcurrent Relays ◽  
Numerical Relay ◽  
Short Circuit Analysis

This Paper deals with the Relay Coordination for microgrids by considering the symmetrical and unsymmetrical faults. A microgrid is an active distribution system in which the renewable energy sources and loads connected to feeders operate parallel or autonomously from the main power grid. In a microgrid, Overcurrent relays can be used as the protection device. When there is changeover from grid connected to islanded mode or disconnection of DG will lead to variation in short circuit current. So, the relay may fail to operate or there will be delay in operation. Relay Coordination is done on the basis of load flow and short circuit analysis. Simulation is done using the ETAP (Electrical Transient and Analysis Program) Software by taking the 9 bus 18 node system.

scholarly journals Optimal over Current Relay Coordination of IEEE 9 Bus System using Mipower

2020 ◽  
Vol 8 (5) ◽  
pp. 1481-1485
Keyword(s):  
Power System ◽  
Short Circuit ◽  
Operating Time ◽  
Test System ◽  
Load Flow ◽  
Circuit Analysis ◽  
Main Function ◽  
Relay Coordination ◽  
Protective Relays ◽  
Short Circuit Analysis

The protective system plays a major role which has great effect on the power system operation. The modern interconnected power system consists of large numbers of protective relays and circuit breakers which constitute an integral part of the protective scheme. The main function of the relay is to sense and locate the fault and sends a command to the breaker to isolate the faulty element. The objective of the relay coordination is to provide primary as well as backup protection from any fault that is likely to occur in the power system. In this paper, overcurrent relay coordination is implemented on an IEEE 9 Bus test system using MiPower software for phase and earth faults. The Load flow analysis and the short circuit analysis on the IEEE 9 Bus test system is initially done followed by relay coordination. Fault MVA and Fault current data obtained from short circuit analysis enables us to obtain operating time of the relays used in the test system. The calculated value of operating time gives the coordinated operation of all the relays. The MiPower software has unique feature which is very useful in proper coordination of overcurrent relays.

scholarly journals Microgrid Protection through Adaptive Overcurrent Relay Coordination

Electricity ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 524-553
Author(s):  
Haneen Bawayan ◽  
Mohamed Younis
Keyword(s):  
Power Flow ◽  
Short Circuit ◽  
Operating Time ◽  
Specific Area ◽  
Short Circuit Current ◽  
Protection System ◽  
Second Phase ◽  
Nonlinear Program ◽  
Overcurrent Relays ◽  
Overcurrent Relay

The inclusion of distributed energy resources (DER) in Microgrids (MGs) comes at the expense of increased changes in current direction and magnitude. In the autonomous mode of MG operation, the penetration of synchronous distributed generators (DGs) induces lower short circuit current than when the MG operates in the grid-connected mode. Such behavior impacts the overcurrent relays and makes the protection coordination difficult. This paper introduces a novel adaptive protection system that includes two phases to handle the influence of fault current variations and enable the MG to sustain its operation. The first phase optimizes the power flow by minimizing the generators’ active power loss while considering tolerable disturbances. For intolerable cases, the second phase opts to contain the effect of disturbance within a specific area, whose boundary is determined through correlation between primary/backup relay pairs. A directional overcurrent relay (DOCR) coordination optimization is formulated as a nonlinear program for minimizing the operating time of the relays within the contained area. Validation is carried out through the simulation of the IEEE 9, IEEE 14, and IEEE 15 bus systems as an autonomous MG. The simulation results demonstrate the effectiveness of our proposed protection system and its superiority to a competing approach in the literature.

scholarly journals Design and computational modeling of fault current limiter topologies

2020 ◽  
Author(s):  
Alexandre Bitencourt ◽  
Daniel H. N. Dias ◽  
Bruno W. França ◽  
Felipe Sass ◽  
Guilherme G. Sotelo
Keyword(s):  
Electric Power ◽  
Distributed Generation ◽  
Distribution System ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Economic Feasibility ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Fault Current Limiters ◽  
Current Limiter

The increase in demand for electric power and the insertion of a distributed generation led to the rise of the short-circuit current in substations. Most of these Brazilian substations were designed decades ago, because of that their equipment may not support the new short-circuit current levels. To protect the installed equipment and avoid excessive costs replacing old devices, it is possible to install Fault Current Limiters (FCLs). This document is a report from an R&D project that evaluated FCL topologies considering real parameters in simulation from used equipment, concluding that the selected FCL topologies accomplished their technical objective. However, before implementing these topologies in the distribution system, one should consider the technical and economic feasibility of using semiconductor switching devices.

scholarly journals Analysis of Effective Three-Level Neutral Point Clamped Converter System for the Bipolar LVDC Distribution

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 691 ◽  
Author(s):  
Ju-Yong Kim ◽  
Ho-Sung Kim ◽  
Ju-Won Baek ◽  
Dong-Keun Jeong
Keyword(s):  
Distribution System ◽  
Low Voltage ◽  
Balance Control ◽  
Short Circuit ◽  
Renewable Energy Sources ◽  
Neutral Point ◽  
Extreme Load ◽  
Zero Sequence ◽  
Zero Sequence Voltage ◽  
Short Circuit Condition

Low-voltage direct current (LVDC) distribution has attracted attention due to increased DC loads, the popularization of electric vehicles, energy storage systems (ESS), and renewable energy sources such as photovoltaic (PV). This paper studies a ±750 V bipolar DC distribution system and applies a 3-level neutral-point clamped (NPC) AC/DC converter for LVDC distribution. However, the 3-level NPC converter is fundamental in the neutral-point (NP) imbalance problem. This paper discusses the NP balance control method using zero-sequence voltage among various solutions to solve NP imbalance. However, since the zero-sequence voltage for NP balance control is limited, the NP voltage cannot be controlled to be balanced when extreme load differences occur. To maintain microgrid stability with bipolar LVDC distribution, it is necessary to control the NP voltage balance, even in an imbalance of extreme load. In addition, due to the bipolar LVDC distribution, the pole where a short-circuit condition occurs limits the short current until the circuit breaker operates, and a pole without a short-circuit condition must supply a stable voltage. Since the conventional 3-level NPC AC/DC converter alone cannot satisfy both functions, an additional DC/DC converter is proposed, analyzed, and verified. This paper is about a 3-level NPC AC/DC converter system for LVDC distribution. It can be used for the imbalance and short-circuit condition in bipolar LVDC distribution through the prototype of the 300 kW 3-level NPC AC/DC converter system and experimented and verified in various conditions.

scholarly journals Active Reduction of Short-Circuit Current in Power Distribution Systems

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 334
Author(s):  
Esteban Pulido ◽  
Luis Morán ◽  
Felipe Villarroel ◽  
José Silva
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Distribution Systems ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Short Circuit Current ◽  
Power Converter ◽  
Power Distribution Systems ◽  
Power Distribution System ◽  
In Series

In this paper, a new concept of short-circuit current (SCC) reduction for power distribution systems is presented and analyzed. Conventional fault current limiters (FCLs) are connected in series with a circuit breaker (CB) that is required to limit the short-circuit current. Instead, the proposed scheme consisted of the parallel connection of a current-controlled power converter to the same bus intended to reduce the amplitude of the short-circuit current. This power converter was controlled to absorb a percentage of the short-circuit current from the bus to reduce the amplitude of the short-circuit current. The proposed active short-circuit current reduction scheme was implemented with a cascaded H-bridge power converter and tested by simulation in a 13.2 kV industrial power distribution system for three-phase faults, showing the effectiveness of the short-circuit current attenuation in reducing the maximum current requirement in all circuit breakers connected to the same bus. The paper also presents the design characteristics of the power converter and its associated control scheme.

scholarly journals Implementation of Optimal Protection Coordination for Microgrids with Distributed Generations Using Quaternary Protection Scheme

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Panida Thararak ◽  
Peerapol Jirapong
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Test System ◽  
Distributed Generations ◽  
Protection Scheme ◽  
Protection Systems ◽  
Overcurrent Relays ◽  
Operation Test ◽  
Multiple Relay ◽  
Flexible Operation

The flexible operation of microgrids, along with the availability of distributed generation (DG) units, causes a variety of changes in short-circuit current levels, magnitudes, and directions, which has undesirable effects on the operation of protection systems. Conventional protection schemes use typical directional overcurrent relays (DOCRs) with limited operating capability, unable to respond to microgrid operations in the manner of short-circuit current changes. In this paper, a quaternary protection scheme implemented with dual-directional overcurrent relays (dual-DOCR) and a protection control strategy is developed for protecting against faults in microgrids, taking into account the existence of DGs and connection and disconnection of DG units. The optimal dual-DOCRs setting and coordination are formulated as an optimization problem solved by evolutionary programming to minimize the relay operating times. The proposed protection scheme is implemented with a centralized protection control system based on the smart grid concept to increase the adaptability of the dual-DOCRs, which have multiple relay setting groups in accordance with system state changes. The simulation case studies are performed using the IEEE 14-bus test system, which is modified as a meshed microgrid operation. Test scenarios, including possible operations of microgrids, DGs availabilities, and different fault events, are analyzed and discussed. The comparative studies and simulation results show that the proposed scheme provides efficient coordination between the primary and backup relays and increases the responsibility of the protection system, which can be observed from the significant reduction in the relay operating times, resulting in the enhancement of selectivity, sensitivity, and speed of microgrid protection systems.

The Impact of Synchronous Distributed Generation (DG) on Distribution System

2015 ◽  
Vol 785 ◽  
pp. 388-392 ◽  
Author(s):  
Hasmaini Mohamad ◽  
Shahrani Shahbudin ◽  
Nofri Yenita Dahlan
Keyword(s):  
Distributed Generation ◽  
Distribution System ◽  
System Performance ◽  
Power Flow ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Voltage Profile ◽  
Before And After ◽  
Potential Benefits ◽  
The Impact

Interconnection of Distributed Generation (DG) in distribution system presents many potential benefits as well as drawbacks. The impacts of DG might vary with the types of generator. This paper presents a study on the impacts of synchronous DG's interconnection in distribution system. Steady state analysis is carried out to analyze the impact of DG on voltage profile and short circuit current considering before and after DG interconnection. Dynamic analysis is also performed for investigating the performance of DG when a part of distribution system is being islanded. Results show that the penetration of DG contributes to the changes of power flow in the system, hence give impacts to the overall system performance.

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