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rate-of-change-of-frequencies
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Stabilizing a DG-fed islanded system through load shedding on the basis of the rate of change of frequency and voltage drop
, Article International Transactions on Electrical Energy Systems ; Volume 25, Issue 10 , June , 2015 , Pages 1976-1991 ; 20507038 (ISSN) ; Reza Alikhani, H. R ; Mortazavi, S. M ; Sharif University of Technology
John Wiley and Sons Ltd
2015
Abstract
The islanding of a distributed generation (DG)-fed distribution system generally results in frequency drop, which means less power is generated than it is needed. The only way of dealing with this problem is shedding loads as the system cannot generate any more electricity. Load shedding is intended to restore balance between generated and consumed power. This paper proposes a new method for load shedding based on the rate of change of frequency (RoCoF) at the first step and on voltage drop at subsequent steps. For this purpose, three lookup tables were created in order to prioritize loads to be shed according to the willingness of subscribers to pay and the RoCoF. The strength of the...
A novel hybrid islanding detection method for inverter-based DGs using SFS and rOCOF
, Article IEEE Transactions on Power Delivery ; Volume 32, Issue 5 , 2017 , Pages 2162-2170 ; 08858977 (ISSN) ; Vahedi, H ; Khazaeli, F ; Oraee, H ; Sharif University of Technology
Abstract
This paper is aimed at proposing a new hybrid method for the islanding detection of distributed-generation (DG) units. Hybrid method operation is based on the combination of an active and a passive method, for which the optimized Sandia frequency shift (SFS) method is used as the selected active method, and rate of change of frequency relay (ROCOF) is used as the passive method. In order to demonstrate the effectiveness of the proposed technique on islanding detection, several simulation studies based on IEEE 1547 and UL1741 anti-islanding test requirements are carried out. The evaluation of simulation results reveals that the control system, based on the proposed hybrid algorithm, meets the...
Power System Frequency Estimation for Protection Application in Accordance with IEC 60255-181
, M.Sc. Thesis Sharif University of Technology ; Hajipour, Ehsan (Supervisor)
Abstract
The frequency of the system is one of the important network parameters that must be continuously monitored. In new power networks, due to the fact that inverter loads and renewable power plants have increased, frequency estimation has faced many problems. Due to the fact that these renewable power plants have little inertia, the networks that include these power plants are faced with rapid frequency changes in the presence of network incidents and transients such as load shedding and power plant blackout or fault, and therefore they should Be equipped with accurate frequency relays or relays to detect the rate of frequency changes. Also, the increase in the amount of harmonic pollution of...
Relay logic for islanding detection in active distribution systems
, Article IET Generation, Transmission and Distribution ; Volume 9, Issue 12 , August , 2015 , Pages 1254-1263 ; 17518687 (ISSN) ; Amraee, T ; Ranjbar, A. M ; Mozafari, B ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
This study presents a passive model to detect islanding conditions of synchronous distributed generation resources in a distribution network or a microgrid. The proposed approach uses the classification and regression tree algorithm for distinguishing between islanding and non-islanding situations. It utilises the rate of change of frequency (ROCOF) and harmonic content of the equivalent reactance seen at the location of distributed generation as input features for decision tree construction. Indeed the thresholds of the proposed input features are extracted by the decision tree algorithm. The output if-then rules of the decision tree algorithm are then utilised to make a new relay logic for...