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.

scholarly journals An Adaptive and Decentralized Protection Scheme for Microgrid Protection

2019 ◽  
Author(s):  
Mahdi Ghotbi Maleki ◽  
Hamid Javadi ◽  
Mojtaba Khederzadeh ◽  
Siamak Farajzadeh
Keyword(s):  
Short Circuit ◽  
Characteristic Curve ◽  
Short Circuit Current ◽  
Distribution Networks ◽  
The Other ◽  
Central Unit ◽  
Backup Protection ◽  
Protection Scheme ◽  
Distributed Generators ◽  
Overcurrent Relays

In this paper a protection scheme is provided to protect microgrid by considering the problems that are generated by addition of distributed generators to distribution networks and change these networks from passive to active. At first, changes in microgrid conditions that can affect short-circuit current is explained. Then Based on these changes, an algorithm is proposed to update relays settings. The algorithm can be used for both instantaneous and inverse time relays. In this protection scheme, central unit has no place and relays are responsible for monitoring microgrid and update their settings. In other words, this protection scheme is an adaptive and decentralized microgrid protection scheme. Instantaneous overcurrent relays are used in this paper. To avoid storing large amounts of setting data in relays memory, a method for calculating pickup current of instantaneous relay is provided. Since digital relays used, a new characteristic curve for instantaneous relay for better performance in the field of backup protection is defined. This new characteristic curve has two peakup currents: one of them for main protection and the other one for backup protection. Then coordination of instantaneous relay using the new characteristic curve is explained. At the end, this protection scheme is implemented on a microgrid.

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 Smart Sensors for Smart Grid Reliability

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2187 ◽  
Author(s):  
Monica Alonso ◽  
Hortensia Amaris ◽  
Daniel Alcala ◽  
Diana M. Florez R.
Keyword(s):  
Smart Grid ◽  
Real Time ◽  
Smart Grids ◽  
Short Circuit ◽  
Test System ◽  
Smart Sensors ◽  
Smart Sensor ◽  
Protection Scheme ◽  
Time Operation ◽  
Real Time Operation

Sensors for monitoring electrical parameters over an entire electricity network infrastructure play a fundamental role in protecting smart grids and improving the network’s energy efficiency. When a short circuit takes place in a smart grid it has to be sensed as soon as possible to reduce its fault duration along the network and to reduce damage to the electricity infrastructure as well as personal injuries. Existing protection devices, which are used to sense the fault, range from classic analog electro-mechanics relays to modern intelligent electronic devices (IEDs). However, both types of devices have fixed adjustment settings (offline stage) and do not provide any coordination among them under real-time operation. In this paper, a new smart sensor is developed that offers the capability to update its adjustment settings during real-time operation, in coordination with the rest of the smart sensors spread over the network. The proposed sensor and the coordinated protection scheme were tested in a standard smart grid (IEEE 34-bus test system) under different short circuit scenarios and renewable energy penetration. Results suggest that the short-circuit fault sensed by the smart sensor is improved up to 80% and up to 64% compared with analog electromechanics relays and IEDs, respectively.

scholarly journals Fault Assessment and Mitigation of the 132kV Transmission Line in Nigeria using Improved Resonant Fault Current Limiting (RFCL) Protection Scheme

2018 ◽  
Vol 3 (10) ◽  
pp. 38-44
Author(s):  
D. C. Idoniboyeobu ◽  
S. L. Braide ◽  
Wigwe Elsie Chioma
Keyword(s):  
Power System ◽  
Transmission Line ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Resonant Circuit ◽  
Fault Current ◽  
Protection Scheme ◽  
Current Limiting ◽  
Simulation Results ◽  
The Impact

This research work proposed an improved Resonant Fault Current Limiting (RFCL) protection scheme to reduce the impact of three-phase short-circuit faults in a power system sub-transmission network. The model used an interpolator-extrapolator technique based on a Resonant Fault Current Limiter (RFCL) for automating the procedure of predicting the required reactor value that must be in resonant circuit to limit the short-circuit current values to permissible values. Using the developed model, short-circuit fault simulations on the three phases of the transmission line (Phase A-C) were performed in the MATLAB-SIMULINK environment. Simulation results were obtained by varying the resonant inductance (reactor) parameter of the RFCL circuit for each of the phases to obtain permissible short-circuit current levels and the values used to program a functional interpolator-extrapolator in MATLAB; the resonant values were typically set to values of inductance equal to 0.001H, 0.01H and from 0.1H to 0.5H in steps of 0.1H. Simulation results revealed the presence of very high short-circuit current levels at low values of the resonant inductor. From the results of simulations, there are indications that the RFCL approach is indeed very vital in the reduction of the short circuit current values during the fault and can safeguard the circuit breaker mechanism in the examined power system sub-transmission system. In addition, lower fault clearing times can be obtained at higher values of inductances; however, the clearance times start to converge at inductance values of 0.1H and above.

scholarly journals Fault Analysis and Design of a Protection System for a Mesh Power System with a Co-Axial HTS Power Cable

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 220 ◽  
Author(s):  
Thai-Thanh Nguyen ◽  
Woon-Gyu Lee ◽  
Hak-Man Kim ◽  
Hyung Yang
Keyword(s):  
Power System ◽  
Fault Analysis ◽  
Protection System ◽  
Power Cable ◽  
Analysis And Design ◽  
Protection Scheme ◽  
System Protection ◽  
Protection Systems ◽  
Overcurrent Relays ◽  
System Characteristics

The uses of high-temperature superconducting (HTS) cables pose a challenge of power system protection since the impedance of the HTS cable is varied during fault conditions. The protection systems should be designed properly to ensure the reliability and stability of the whole system. This paper presents a fault analysis of the co-axial HTS cable in the mesh system and proposes a coordinated protection system. In the proposed protection system, the main protection is the differential current relay whereas the backup protections are the overcurrent and directional overcurrent relays. The normal and abnormal relay operations are considered to analyze the transient fault current in the HTS cable and evaluate the performance of the proposed coordinated protection system. Characteristics of cable impedances and temperatures under various fault conditions are presented. The proposed protection scheme is validated by the simulation in the PSCAD/EMTDC program. Simulation results show that the coordinated protection scheme could successfully protect the HTS cables in both normal and abnormal relay operations.

Experiment of a Resistive Superconducting Fault Current Limiter Based on MgB2 under Different Supply Voltages

2013 ◽  
Vol 721 ◽  
pp. 527-530
Author(s):  
Lei Yao ◽  
Jun Mei ◽  
Jian Yong Zheng ◽  
Bin Liu ◽  
You Xu
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Test System ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Voltage Level ◽  
Superconducting Fault Current Limiter ◽  
Current Limiting ◽  
Current Limiter ◽  
Test Result

In order to limit the short-circuit current, and to prevent the power grid and its equipment from the shock of the short circuit, the fault current limiter with detection, trigger and limiting was introduced. A small resistive type superconducting fault current limiter prototype based on MgB2, cooled by liquid helium and heliumgas, was developed and tested by a test system. The test result showed that the prototype based on MgB2 produced superior limiting performance, the short-circuit current suppressing ratio was up to more than 45%, and with the rise of the voltage level, the current limiting capability was also gradually increased, up to 56%.

Microgrid Protection Based on Specific Current Injection

2013 ◽  
Vol 805-806 ◽  
pp. 1082-1086
Author(s):  
Jun Li ◽  
Zhi Fei Chen ◽  
Jun Xia Qian ◽  
Hui Gang Zhang
Keyword(s):  
Power Flow ◽  
Short Circuit ◽  
Distribution Network ◽  
Short Circuit Current ◽  
Current Injection ◽  
Harmonic Current ◽  
Matlab Simulink ◽  
Injection Method ◽  
Protection Scheme ◽  
Fault Type

Considering that microgrid (MG) can be controlled flexibly, its short circuit-current is limited and power flow is bidirectional. The paper presents a new relay protection scheme of microgrid based specific harmonic injection method. The injective harmonic flows all over microgrid and the amplitude of specific harmonic current will enhance in fault occasion. So the above characteristic can solve the problem of fault position and the symmetric characteristic can complete the identification of fault type. The discussion about the compatibility of microgrid protection and conventional distribution network line protection. At last, the combined microgrid model is built in Matlab/Simulink environment. The simulation result demonstrated that the above method can complete the identification of fault position and type and it also can coordinate with the traditional line protection well.

scholarly journals Analysis of Characteristics Over Current Relay and Ground Fault Relay on Feeder Rayon Tabing

2018 ◽  
Vol 248 ◽  
pp. 02006
Author(s):  
Arzul ◽  
Ija Darmana ◽  
Erliwati ◽  
Adiv Rama Salvayer ◽  
Tris Safri Yetno
Keyword(s):  
Electric Power ◽  
Power Distribution ◽  
Short Circuit ◽  
Relay Protection ◽  
Short Circuit Current ◽  
Phase 2 ◽  
Current Analysis ◽  
Protection Relay ◽  
Ground Fault ◽  
Overcurrent Relays

The reliability of power distribution of PT PLN (Persero) branch of Padang especially in Rayon Tabing most of the repeaters is still not optimal. This is due to an uncoordinated protection relay on each feeder. One effort made to improve the reliability of electric power is to rearrange the protection of overcurrent relays and ground disturbance relays on the feeder. So coordinated with each other well and is expected if there is interference in one of the repeater will not bring black out on other repeater. In this research we analyzed short circuit current at 20 kV side. From the analysis results obtained new relay protection settings based on the calculation of short-circuit current settings and compare the results with existing protection relays. By making efforts to improve the reliability of electric power is to rearrange the protection relay on each feeder. Based on short circuit current analysis on each repeater, the largest short circuit in 3 phase, 2 phase, and 1 phase disturbance is located at 1% disturbance location and the smallest disturbance is at 100% disturbance location. It can be concluded that the farther the location of the disturbance that occurs the smaller the disturbance, and vice versa, if the location of the disturbance that occurs closer then the greater the noise flow.

scholarly journals New Protection Scheme for Internal Fault of Multi-Microgrid

2017 ◽  
Author(s):  
Fan Zhang ◽  
Longhua Mu ◽  
Wenming Guo
Keyword(s):  
Control Strategy ◽  
Simulation Analysis ◽  
High Sensitivity ◽  
Distribution Characteristics ◽  
Distributed Generations ◽  
Protection Scheme ◽  
Fault Currents ◽  
Internal Fault ◽  
Simulation Results ◽  
Flexible Operation

Multi-microgrid has many new characteristics, such as bi-directional power flows, flexible operation modes and variable fault currents with different control strategy of inverter interfaced distributed generations (IIDGs). All these featuring aspects pose challenges to multi-microgrid protection. In this paper, current and voltage characteristics of different feeders are analyzed when fault occurs in different positions of multi-microgrid. Based on the voltage and current distribution characteristics of the line parameters, a new protection scheme for the internal fault of multi-microgrid is proposed, which takes the change of phase difference and amplitude of measured bus admittance as the criterion. This scheme with high sensitivity and reliability, has a simple principle and is easy to be adjusted. PSCAD/EMTDC is used in simulation analysis, and simulation results have verified the correctness and effectiveness of the protection scheme.

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