scholarly journals Improved Three-Phase AFD Islanding Detection Based on Digital Control and Non-Detection Zone Elimination

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2421
Author(s):  
Xinxin Zheng ◽  
Rui Zhang ◽  
Xi Chen ◽  
Nong Sun
Keyword(s):  
Control System ◽  
Phase Angle ◽  
Digital Control ◽  
Detection Method ◽  
Frequency Drift ◽  
Phase System ◽  
Islanding Detection ◽  
Detection Zone ◽  
Three Phase ◽  
Three Phase Inverter

This paper proposes an improved active frequency drift (AFD) islanding detection method of a three-phase inverter. Different than the existing single-phase AFD method, in the three-phase system, the disturbance is added to the phase angle, which takes part in coordinate transformation calculations. Thus, the frequency drift of the three-phase reference current can be realized by the disturbance of the phase angle. It is unnecessary to add frequency drift to each phase respectively with the proposed method, which can simplify the control system. Furthermore, the non-detection zone can be eliminated by updating certain parameters; therefore, the detection method is sensitive. In this paper, the application of the proposed method in a digital control system is discussed in detail. The non-detection zone is analyzed, and an elimination method is proposed. Finally, the simulation and experimental results are given to verify the theoretical analysis.

Composite Islanding Detection Method of Grid-Connected Photovoltaic Generation System

2013 ◽  
Vol 339 ◽  
pp. 574-578
Author(s):  
Guo Zhao ◽  
Xue Liang Huang
Keyword(s):  
Detection Method ◽  
Islanding Detection ◽  
Generation System ◽  
Photovoltaic Generation ◽  
Three Phase ◽  
Reactive Current ◽  
Environment Simulation ◽  
Simulation Results ◽  
Pv Generation ◽  
Three Phase Inverter

Islanding detection is an important issue for grid-connected photovoltaic (PV) generation systems. The paper puts forward a new composite islanding detection method combining active current disturbance and reactive current disturbance. This islanding detection method for three-phase inverter is simulated in the Matlab/Simulink environment. Simulation results show that, when the inverter output and the load power are balanced, the new islanding detection method can detect islanding quickly with little influence on the power quality.

scholarly journals Evaluation of Passive Islanding Detection Methods for Line to Ground Unsymmetrical Fault in Three Phase Microgrid Systems: Microgrid Islanding Detection Method

2021 ◽  
Vol 11 (5) ◽  
pp. 7591-7597
Author(s):  
L. Bangar Raju ◽  
K. Subba Rao
Keyword(s):  
Phase Angle ◽  
Power Distribution ◽  
Distribution Systems ◽  
Detection Method ◽  
Rate Of Change ◽  
Detection Methods ◽  
Islanding Detection ◽  
Detection Zone ◽  
Local Methods ◽  
Nuisance Tripping

Distributed Generators (DGs) are incorporated in the power distribution systems to develop green energies in microgrids. Islanding is a challenging task in a microgrid. Different types of islanding methods, e.g. local and remote methods, have been developed for handling this task, with local methods being easier to implement, while remote methods are communication-based and costly. The local methods are classified as passive, active, and hybrid, out of which the passive methods are more simple and economical. In this paper, a passive islanding detection method is proposed to detect single line to ground fault. This fault is considered to represent the 60 to 70% of the total un-intentional faults of this category. The available passive methods cannot detect islanding at lower power mismatches as the variations in voltage and frequency fall within thresholding values. In this method, the voltage signals are first retrieved at the targeted DG output and then the phase angle is estimated. Finally, the phase angle is differentiated to get Rate Of Change Of Voltage Phase Angle (ROCOVPA) to detect islanding, and then it is compared with the Rate Of Change Of Frequency (ROCOF) at zero percent power mismatch. Simulation results depict that the ROCOVPA is more effective than ROCOF. The proposed method not only reduces detection time and Non-Detection Zone (NDZ) but is also stable during non-islanding cases like load connection and disconnection to avoid nuisance tripping.

Direct Current Deadbeat Predictive Controller for BLDC Motor Using Single DC-Link Current Sensor

2020 ◽  
Vol 38 (8A) ◽  
pp. 1187-1199
Author(s):  
Qaed M. Ali ◽  
Mohammed M. Ezzalden
Keyword(s):  
Control System ◽  
High Speed ◽  
Fast Response ◽  
Bldc Motor ◽  
Current Controller ◽  
Three Phase ◽  
Predictive Controller ◽  
Two Phases ◽  
Dc Current ◽  
Three Phase Inverter

BLDC motors are characterized by electronic commutation, which is performed by using an electric three-phase inverter. The direct control system of the BLDC motor consists of double loops; including the inner-loop for current regulating and outer-loop for speed control. The operation of the current controller requires feedback of motor currents; the conventional current controller uses two current sensors on the ac side of the inverter to measure the currents of two phases, while the third current would be accordingly calculated. These two sensors should have the same characteristics, to achieve balanced current measurements. It should be noted that the sensitivity of these sensors changes with time. In the case of one sensor fails, both of them must be replaced. To overcome this problem, it is preferable to use one sensor instead of two. The proposed control system is based on a deadbeat predictive controller, which is used to regulate the DC current of the BLDC motor. Such a controller can be considered as digital controller mode, which has fast response, high precision and can be easily implemented with microprocessor. The proposed control system has been simulated using Matlab software, and the system is tested at a different operating condition such as low speed and high speed.

scholarly journals Over/Undervoltage and Undervoltage Shift of Hybrid Islanding Detection Method of Distributed Generation

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Manop Yingram ◽  
Suttichai Premrudeepreechacharn
Keyword(s):  
Control System ◽  
Distributed Generation ◽  
Hybrid Method ◽  
Detection Method ◽  
System Simulation ◽  
Detection Methods ◽  
Islanding Detection ◽  
Active Method ◽  
Passive Method ◽  
Simulation Results

The mainly used local islanding detection methods may be classified as active and passive methods. Passive methods do not perturb the system but they have larger nondetection zones, whereas active methods have smaller nondetection zones but they perturb the system. In this paper, a new hybrid method is proposed to solve this problem. An over/undervoltage (passive method) has been used to initiate an undervoltage shift (active method), which changes the undervoltage shift of inverter, when the passive method cannot have a clear discrimination between islanding and other events in the system. Simulation results on MATLAB/SIMULINK show that over/undervoltage and undervoltage shifts of hybrid islanding detection method are very effective because they can determine anti-islanding condition very fast.ΔP/P>38.41% could determine anti-islanding condition within 0.04 s;ΔP/P<-24.39% could determine anti-islanding condition within 0.04 s;-24.39%≤ΔP/P≤ 38.41% could determine anti-islanding condition within 0.08 s. This method perturbed the system, only in the case of-24.39% ≤ΔP/P ≤38.41% at which the control system of inverter injected a signal of undervoltage shift as necessary to check if the occurrence condition was an islanding condition or not.

The Analysis of the Performance of Active Frequency Drift Islanding Method

2013 ◽  
Vol 846-847 ◽  
pp. 750-755
Author(s):  
Wen Huang ◽  
Tao Zheng ◽  
Shi Guang Xu ◽  
Zhi Yuan Liu ◽  
Jing Hua Wen
Keyword(s):  
Frequency Characteristic ◽  
Detection Method ◽  
Frequency Drift ◽  
Islanding Detection ◽  
Factors Affecting ◽  
Distributed Generator ◽  
Major Factors

Active frequency drift islanding detection method is one of most widely used in the distributed generator islanding detection. Now domestic researches of islanding detection have not been done deep researched about the reason why islanding detection method will become invalid. Therefore, the paper analyses the performances of the frequency drift islanding method from load phase frequency characteristic and algorithm phase frequency characteristic, which are the major factors affecting the effectiveness of islanding detection method. At last, this paper proved the analysis results with MATLAB.

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