scholarly journals A Novel Hybrid Active Anti-Islanding Method For Multi-Converter Fed Distributed Generation Systems

2021 ◽  
Author(s):  
Sasan Mostafaei

This thesis presents a novel active anti-islanding detection scheme for the three phase gridconnected converters. The proposed hybrid method works based on the combination of Positive Feedback Frequency Shift (PFFS) and Reactive Power Variation (RPV) methods, and therefore it combines the features of both methods. Unlike the RPV scheme, this method is capable of synchronizing all power converters with each other in a distributed generation (DG) system. Therefore, it can effectively detect islanding when the DG system has multiple renewable energy sources interfaced to the system by multiple converters. The proposed method can also be combined with other active methods, such as the active frequency drift method. This minimizes the power quality degradation since the scheme is called upon only when 0.1Hz deviation in the grid frequency is detected. Moreover, unlike other positive feedback methods, this scheme has little impact on the stability of the DG system, since the positive feedback reference is only limited to

2021 ◽  
Author(s):  
Sasan Mostafaei

This thesis presents a novel active anti-islanding detection scheme for the three phase gridconnected converters. The proposed hybrid method works based on the combination of Positive Feedback Frequency Shift (PFFS) and Reactive Power Variation (RPV) methods, and therefore it combines the features of both methods. Unlike the RPV scheme, this method is capable of synchronizing all power converters with each other in a distributed generation (DG) system. Therefore, it can effectively detect islanding when the DG system has multiple renewable energy sources interfaced to the system by multiple converters. The proposed method can also be combined with other active methods, such as the active frequency drift method. This minimizes the power quality degradation since the scheme is called upon only when 0.1Hz deviation in the grid frequency is detected. Moreover, unlike other positive feedback methods, this scheme has little impact on the stability of the DG system, since the positive feedback reference is only limited to


Author(s):  
S. Govinda Raju ◽  
K. Harinadha Reddy ◽  
Ch. Rami Reddy

Background: The growth of renewable energy sources is increasing in the world to meet the energy consumption demand. The major problem after the integration of renewable sources is islanding. The islanding is not safe for equipment and customers. As per Distributed Generation (DG) interconnection standards, it should be detected within 2 seconds. Objective: This paper presents the review of various islanding detection methods for increasing the stability of islanded DG. This will help future researchers for selecting the best islanding detection method with zero NDZ. Methods & Results: The islanding detection methods are classified as local and remote techniques. The local techniques are again classified as active, passive and hybrid methods. Each method is presented with their islanding detection time, power quality issues, Non Detection Zone (NDZ), advantages and disadvantages. Conclusion: The fuzzy based artificial intelligence with Particle Swarm Optimization (PSO) passive methods have been reduced the NDZ to zero and increase the stability of DG without degrading the power quality as active and passive methods.


Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2819 ◽  
Author(s):  
Reza Zamani ◽  
Mohamad-Esmail Hamedani-Golshan ◽  
Hassan Haes Alhelou ◽  
Pierluigi Siano ◽  
Hemanshu R. Pota

There has been a considerable importance for the islanding detection due to the growing integration of distributed generations (DGs) in the modern power grids. This paper proposes a novel active islanding detection scheme for synchronous DGs, considering two additional compensators and a positive feedback for each of active and reactive power control loops. The added blocks are designed using the small gain theorem and stability margins definition considering characteristics of open loop transfer functions of synchronous DG control loops. Islanding can be detected using the proposed method even where there is an exact match between generation and local load without sacrificing power quality. In addition, the performance of the proposed method can be retained even with high penetration of motor loads. The proposed scheme improves the stability and power quality of the grid, when the synchronous DG is subjected to the grid-connected disturbances. Furthermore, this method augments the stability margins of the system in the grid-connected conditions to enhance the disturbances ride-through capability of the system and reduce the negative impact of the active methods on the power quality. Simultaneous advantages of the proposed scheme are demonstrated by modeling a test system in MATLAB software and time-domain simulation achieved by PSCAD.


Author(s):  
Bineeta Soreng ◽  
Raseswari Pradhan

In this paper, an optimal controller-based islanding detection scheme is proposed for an inverter-based distributed generation system (DGS). Islanding is both harmful and unsafe but unavoidable state in a DGS. Therefore, islanding state is required to be detected quickly and accurately. A reactive power control strategy for islanding is presented in this work. It is reported that the active and reactive power mismatches in a DGS forces its voltage or frequency to deviate. That deviation is recorded continuously in this scheme and islanding state is reported when the deviation touches the thresholds. To help in this tracking process, a modified H8-based optimal controller whose parameters are tuned with LMI is proposed. It can offer both feedback and feed-forward control actions. The proposed DGS is modelled using MATLAB/SIMULINK and tested taking several case studies. It is found that, islanding condition is rapidly detected compared to that of the uncontrolled scheme yielding an optimal solution. Further, it is an inexpensive, robust, compact in structure and very easy to implement too.


Author(s):  
J. Rajesh Reddy ◽  
A. Pandian

<p>In recent years to meet the energy consumption demand of the world, all are working on renewable distributed generation (RDG) due to shortage of fossil fuels. The RDG systems after integrating with grid, has a disadvantage of islanding in the power system. Islanding is caused, if the RDG is supplying power to load connected due to failures in the grid. As per IEEE 1547 distributed generation (DG) interconnection standards, the islanding should be detected within 2 seconds after islanding. In this paper a hybrid islanding detection scheme is presented with rate of change of frequency (ROCOF) and reactive power injection with positive feedback. It will reduce the non detection zone (NDZ) of passive ROCOF relay to zero and can detect balanced islanding. The computer simulations are performed on MATLAB-2016. The simulations results show the effective performance of the proposed method.</p>


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