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An interval type-2 fuzzy logic based strategy for microgrid protection
Bukhari, Syed Basit Ali,Haider, Raza,Saeed Uz Zaman, Muhammad,Oh, Yun-Sik,Cho, Gyu-Jung,Kim, Chul-Hwan IPC Science and Technology Press 2018 International journal of electrical power energy s Vol.98 No.-
<P><B>Abstract</B></P> <P>The concept of microgrids has been introduced to facilitate the integration of the distributed energy resources (DERs) into distribution networks in a more economical, reliable and environment-friendly manner. One of the critical challenges associated with microgrids is devising an appropriate protection strategy. This is because the fault current level continuously varies owing to the existence of DERs and to the fact that the microgrid can operate in grid-tied and islanded modes. This paper proposes a new protection strategy for microgrids using an interval type-2 fuzzy logic system. The proposed strategy considers various uncertainties associated with faults and employs two different fuzzy systems to detect, classify, and locate the faults in microgrids. The phase angle between superimposed modal voltage and modal current is used as an input to the fuzzy system designed to identify the fault direction. The significant feature of the proposed strategy is that it can protect the microgrid after a single-phase tripping event. To validate the effectiveness of the proposed strategy, we have performed extensive simulations using MATLAB/SIMULINK. The simulation results show that the proposed strategy can detect, classify, and isolate various faults in the microgrid. Moreover, the strategy also provides backup protection in case of failure of the primary protection.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Develop a new microgrid protection strategy based on interval type-2 fuzzy logic system. </LI> <LI> Considers various uncertainties associated with faults in microgrids. </LI> <LI> Identify fault direction using phase angle between superimposed modal voltage and modal current. </LI> <LI> Capable to protect the microgrid after a single-phase tripping event. </LI> </UL> </P>
Gush, Teke,Bukhari, Syed Basit Ali,Haider, Raza,Admasie, Samuel,Oh, Yun-Sik,Cho, Gyu-Jung,Kim, Chul-Hwan IPC Science and Technology Press 2018 International journal of electrical power energy s Vol.102 No.-
<P>The concept of microgrids has been proposed as an economical, reliable, and efficient way to integrate a large number of distributed energy resources (DERs) into distribution networks. To ensure the safe operation of a microgrid fast and accurate fault detection and location are crucial. This paper proposes fault detection and location in a microgrid using mathematical morphology (MM) and recursive least-square (RLS) methods. The proposed method first applies dilation and erosion median filter (DEMF) on a current signal to detect and classify the faults in microgrids. Then, the RLS method estimates the fault location using a differential equation derived from an equivalent model of the microgrid. The performance of the proposed method is evaluated on a medium voltage microgrid test system through simulations using MATLAB/SIMULINK. The simulation results depict that the proposed method provides faster fault detection and accurate fault location.</P>
Frequency Profile Improvement of a Microgrid under Abnormal Conditions via a Demand Response Program
Muhammad Saeed uz Zaman,Raza Haider,Syed Basit Ali Bukhari,Yun-Sik Oh,Min-Sung Kim,Muhammad Mehdi,Chul-Hwan Kim 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.10
The frequency deviation of an electric power system from its nominal range is a significant indicator of the system’s instability. This issue is further highlighted when the system is incorporated with intermittent renewable energy resources. In this work, the frequency regulation of a microgrid is achieved by a demand response program. The proposed plan is implemented in a central controller that has two control sections. The frequency deviation is controlled by manipulating responsive loads. In the case of higher frequency deviation, the command of the first control section is proportional to the magnitude of frequency deviation and a large amount of responsive loads is manipulated to restore the frequency to its nominal range quickly. The other section of the central controller addresses minor frequency deviations. The proposed plan is implemented on a test system and outperforms the conventional methods in terms of frequency restoration. The improvement in voltage profile is also observed during abnormal conditions after the proposed plan is implemented.
Protection Coordination Using Superconducting Fault Current Limiters in Microgrids
Raza Haider,Muhammad Saeed Uz Zaman,Syed Basit Ali Bukhari,Zahoor Ahmed,Muhammad Mehdi,Yun-Sik Oh,Chul-Hwan Kim 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.10
Power generating units in the form of distributed generation (DG) are integrating with microgrid (MG) systems to supply reliable power to users. The trend of an integrated power supply is increasing continually to meet growing energy demands. Besides certain advantages of the MG system, some interconnection and system protection issues pose a challenge in terms of implementation. These problems need to be addressed in order to facilitate smooth operation of power systems. Superconducting fault current limiters (SFCLs) provide the best performance and unique protection features to electrical power systems during various fault conditions. This paper describes modeling, characterization, and implementation of SFCL in an MG system to enhance protection coordination. The proposed SFCL is modeled in MATLAB/ Simulink software and the performance of the system is validated through simulation results. It is also shown that the proposed SFCL provides a means of better relay coordination during various fault conditions. This is achieved by incorporating well-calculated design parameters of SFCL and its placement at optimal locations.
Saeed Zaman Jamali,Muhammad Omer Khan,Syed Basit Ali Bukhari,Muhammad Mehdi,Gi-Hyeon Gwon,Chul-Ho Noh,Chul-Hwan Kim 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.10
Low voltage DC (LVDC) distribution systems are gaining attention as customer loads are shifting towards power electronics-based equipment. The DC distribution system has the advantage of supplying power to these power electronic-based loads with high efficiency and without undergoing an energy conversion process. However, the power electronic components used in the LVDC distribution system are vulnerable during short-circuit faults. These components must be protected during the short-circuit faults for a safe and reliable operation. Therefore, this paper proposes a protection technique based on DC short-circuit fault current behavior. The fault is detected via a superposition principle. A fault current limiter (FCL) is used to suppress DC fault strength and reduce the stress from the circuit breaker. Finally, a solid state circuit breaker (SSCB) is used to isolate the fault point. The simulation results show that the proposed protection Scheme operates quickly enough as per expectations to avoid damage to sensitive power electronic devices.