skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: A New Harmonic-based Protection structure for Meshed Microgrids
This paper presents a novel harmonic-based overcurrent relay which detects and isolates three-phase faults in a meshed microgrid. The harmonic signals are generated by two Distributed Generators (DGs) which each of them communicate with its adjacent DG. In the first step, a set of features are extracted from DG output signal and then fed to a Support Vector Machine (SVM) to detect occurrence of fault. Once the fault is detected, based on minimum voltage measured by DG, two closest DGs will recognize and these two DGs inject two distinct harmonics to activate harmonic-based relays. As each set of relays located at either beginning or end of each section is activated by current with specific frequency, these relays behave like directional relays without using voltage transformers. As a result, the proposed method is cost-effective solution. The optimum Time Dial Settings (TDSs) of these relays are obtained by solving a coordination problem with Particle Swarm Optimization (PSO) algorithm. Real-time results are taken by OPAL-RT to show the effectiveness of the proposed method for two different locations of fault in a meshed microgrid.  more » « less
Award ID(s):
1650470 1747757
PAR ID:
10082514
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
2018 IEEE Power & Energy Society General Meeting (PESGM)
Page Range / eLocation ID:
1 to 6
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, 2018 IEEE Energy Conversion Congress and Exposition (ECCE))
    This paper presents a novel noncommunication protection architecture based on utilizing the selected Distributed Generators (DGs) which provide high-frequency harmonics for harmonic-based overcurrent relays to detect and isolate three-phase faults in meshed microgrids. The most prominent features of this structure include limited number of DGs required to inject harmonics, no need for using centralized communication system, and the fault can be detected and located in all conditions such as load disconnection/connection and DG disconnection/connection. The optimum Time Dial Settings (TDSs) of these relays are obtained by solving a coordination problem with Particle Swarm Optimization (PSO) algorithm. Real-time results are produced using OPAL-RT to show the effectiveness of the proposed method for two different locations of faults in a meshed microgrid. 
    more » « less
  2. ; ; ; ; (, IET Generation, Transmission & Distribution)
    This paper proposes a novel method to locate faults in an AC‐meshed microgrid. To this end, a set of features is first extracted and selected from the measured signals and fed to a Support Vector Machine (SVM) to detect the occurrence of fault. Then, the Distributed Generator (DG) with the lowest amount of fundamental voltage, which is the closest one to the fault, injects an appropriate voltage/current harmonic. As the faulted section has the lowest impedance value from the Point of Common Coupling of the DG, the harmonic current of the corresponding line has the highest value. Based on this fact, the first candidate DG sends a notification signal to the second candidate DG, in which the fault occurs between them. Finally, the impedances in the injected frequency are measured from these two DGs and fed into a multi‐class SVM to locate the faulted line. The proposed method has the ability to locate faults for islanded and grid‐connected microgrids with variable configurations. Real‐time simulation results are taken by OPAL‐RT to show the effectiveness of the proposed method in the meshed microgrid. 
    more » « less
  3. ; ; ; ; ; (, IEEE Transactions on Power Systems)
    null (Ed.)
    In this paper, we introduce a distributed secondary voltage and frequency control scheme for an islanded ac microgrid under event-triggered communication. An integral type event-triggered mechanism is proposed by which each distributed generator (DG) periodically checks its triggering condition and determines whether to update its control inputs and broadcast its states to neighboring DGs. In contrast to existing event-triggered strategies on secondary control of microgrids, the proposed event-triggered mechanism is able to handle the consensus problem in case of asynchronous communication. Under the proposed sampled-data based event-triggered mechanism, DGs do not need to be synchronized to a common clock and each individual DG checks its triggering condition periodically, relying on its own clock. Furthermore, the proposed method efficiently reduces communication rate. We provide sufficient conditions under which microgrid's frequency and a critical bus voltage asymptotically converge to the nominal frequency and voltage, respectively. Finally, effectiveness of our proposed method is verified by testing different scenarios on an islanded ac microgrid benchmark in the MATLAB/Simulink environment as well as a hardware-in-the-loop (HIL) platform, where the physical system is modeled in the Opal-RT and the cyber system is realized in Raspberry Pis. 
    more » « less
  4. ; ; ; (, IET Generation, Transmission & Distribution)
    Microgrid, which is one of the main foundations of the future grid, inherits many properties of the smart grid such as, self‐healing capability, real‐time monitoring, advanced two‐way communication systems, low voltage ride through capability of distributed generator (DG) units, and high penetration of DGs. These substantial changes in properties and capabilities of the future grid result in significant protection challenges such as bidirectional fault current, various levels of fault current under different operating conditions, necessity of standards for automation system, cyber security issues, as well as, designing an appropriate grounding system, fast fault detection/location method, the need for an efficient circuit breaker for DC microgrids. Due to these new challenges in microgrid protection, the conventional protection strategies have to be either modified or substituted with new ones. This study aims to provide a comprehensive review of the protection challenges in AC and DC microgrids and available solutions to deal with them. Future trends in microgrid protection are also briefly discussed. 
    more » « less
  5. ; ; ; ; (, IEEE Transactions on Industrial Electronics)
    Fault Current Limiters (FCLs) are one of the main solutions to upcoming challenges in microgrid protection. Regarding the high penetration of distributed generations (DGs) in future power system, designing cheap and effective FCL is a necessity. The present study addresses this issue by proposing an embedded FCL operating based on modifying the secondary control of four-wire DG. As this method is presented for a four-wire system, besides very low implementing cost, it has independency and flexibility to only limit the current of DG faulted phase. This study also provides real-time simulation results by OPAL-RT to compare the proposed method with a virtual-impedance-based FCL to validate its effectiveness. Finally, experimental results are presented to validate the effectiveness of the proposed FCL. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email