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 Short Circuit Faults Identification and Localization in IEEE 34 Nodes Distribution Feeder Based on the Theory of Wavelets

2018 ◽  
Vol 14 (1) ◽  
pp. 65-79
Author(s):  
Sara Authafa
Keyword(s):  
Fault Location ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Discrete Wavelet ◽  
Detection Scheme ◽  
Protection Scheme ◽  
System Protection ◽  
Fault Type ◽  
Distribution Feeder ◽  
System States

In this paper a radial distribution feeder protection scheme against short circuit faults is introduced. It is based on utilizing the substation measured current signals in detecting faults and obtaining useful information about their types and locations. In order to facilitate important measurement signals features extraction such that better diagnosis of faults can be achieved, the discrete wavelet transform is exploited. The captured features are then utilized in detecting, identifying the faulted phases (fault type), and fault location. In case of a fault occurrence, the detection scheme will make a decision to trip out a circuit breaker residing at the feeder mains. This decision is made based on a criteria that is set to distinguish between the various system states in a reliable and accurate manner. After that, the fault type and location are predicted making use of the cascade forward neural networks learning and generalization capabilities. Useful information about the fault location can be obtained provided that the fault distance from source, as well as whether it resides on the main feeder or on one of the laterals can be predicted. By testing the functionality of the proposed scheme, it is found that the detection of faults is done fastly and reliably from the view point of power system protection relaying requirements. It also proves to overcome the complexities provided by the feeder structure to the accuracy of the identification process of fault types and locations. All the simulations and analysis are performed utilizing MATLAB R2016b version software package.

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 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 Photovoltaic Maximum Penetration Limits on Medium Voltage Overhead and Underground Cable Distribution Feeders: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3843
Author(s):  
Sultan Sh. Alanzi ◽  
Rashad M. Kamel
Keyword(s):  
Power System ◽  
Power Factor ◽  
Distribution System ◽  
Power Flow ◽  
Underground Cables ◽  
Overhead Lines ◽  
Medium Voltage ◽  
Load Power ◽  
Bus Voltage ◽  
Pv Penetration

This paper investigates the maximum photovoltaic (PV) penetration limits on both overhead lines and underground cables medium voltage radial distribution system. The maximum PV penetration limit is estimated considering both bus voltage limit (1.05 p.u.) and feeder current ampacity (1 p.u.). All factors affect the max PV penetration limit are investigated in detail. Substation voltage, load percentage, load power factor, and power system frequency (50 Hz or 60 Hz) are analyzed. The maximum PV penetration limit associated with overhead lines is usually higher than the value associated with the underground cables for high substation voltage (substation voltage = 1.05 and 1.04 p.u.). The maximum PV penetration limit decreases dramatically with low load percentage for both feeder types but still the overhead lines accept PV plant higher than the underground cables. Conversely, the maximum PV penetration increases with load power factor decreasing and the overhead lines capability for hosting PV plant remains higher than the capability of the underground cables. This paper proved that the capability of the 60-Hz power system for hosting the PV plant is higher than the capability of 50 Hz power system. MATLAB software has been employed to obtain all results in this paper. The Newton-Raphson iterative method was the used method to solve the power flow of the investigated systems.

Protection Scheme for DC Microgrid Distribution System

2012 ◽  
Vol 614-615 ◽  
pp. 1661-1665
Author(s):  
Ling Hui Deng ◽  
Zhi Xin Wang ◽  
Jian Min Duan
Keyword(s):  
Distribution System ◽  
Cost Efficiency ◽  
Power Flow ◽  
Low Voltage ◽  
Dc Microgrid ◽  
Protection Scheme ◽  
High Level ◽  
Bidirectional Power Flow ◽  
Efficiency And Reliability ◽  
Laboratory Prototype

The low voltage DC (LVDC) distribution system is a new concept and a promising technology to be used in the future smart distribution system having high level cost-efficiency and reliability. In this paper, a low-voltage (LV) DC microgrid protection system design is proposed. Usually, an LVDC microgrid must be connected to an ac grid through converters with bidirectional power flow and, therefore, a different protection scheme is needed. This paper describes practical protection solutions for the LVDC network and an LVDC system laboratory prototype is being experimentally tested by MATLAB/SIMULINK. The results show that it is possible to use available devices to protect such a system. But other problems may arise which needs further study.

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