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A New Islanding Detection Method Based on Feature Recognition Technology
Xinxin Zheng,Lan Xiao,Wenwen Qin,Qing Zhang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2
Three-phase grid-connected inverters are widely applied in the fields of new energy power generation, electric vehicles and so on. Islanding detection is necessary to ensure the stability and safety of such systems. In this paper, feature recognition technology is applied and a novel islanding detection method is proposed. It can identify the features of inverter systems. The theoretical values of these features are defined as codebooks. The difference between the actual value of a feature and the codebook is defined as the quantizing distortion. When islanding happens, the sum of the quantizing distortions exceeds the threshold value. Thus, islanding can be detected. The non-detection zone can be avoided by choosing reasonable features. To accelerate the speed of detection and to avoid miscalculation, an active islanding detection method based on feature recognition technology is given. Compared to the active frequency or phase drift methods, the proposed active method can reduce the distortion of grid-current when the inverter works normally. The principles of the islanding detection method based on the feature recognition technology and the improved active method are both analyzed in detail. An 18 kVA DSP-based three-phase inverter with the SVPWM control strategy has been established and tested. Simulation and experimental results verify the theoretical analysis.
A New Islanding Detection Method Based on Feature Recognition Technology
Zheng, Xinxin,Xiao, Lan,Qin, Wenwen,Zhang, Qing The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2
Three-phase grid-connected inverters are widely applied in the fields of new energy power generation, electric vehicles and so on. Islanding detection is necessary to ensure the stability and safety of such systems. In this paper, feature recognition technology is applied and a novel islanding detection method is proposed. It can identify the features of inverter systems. The theoretical values of these features are defined as codebooks. The difference between the actual value of a feature and the codebook is defined as the quantizing distortion. When islanding happens, the sum of the quantizing distortions exceeds the threshold value. Thus, islanding can be detected. The non-detection zone can be avoided by choosing reasonable features. To accelerate the speed of detection and to avoid miscalculation, an active islanding detection method based on feature recognition technology is given. Compared to the active frequency or phase drift methods, the proposed active method can reduce the distortion of grid-current when the inverter works normally. The principles of the islanding detection method based on the feature recognition technology and the improved active method are both analyzed in detail. An 18 kVA DSP-based three-phase inverter with the SVPWM control strategy has been established and tested. Simulation and experimental results verify the theoretical analysis.
Ch. Rami Reddy,K. Harinadha Reddy 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.2
Grid integration of renewable energy sources in distributed generation (DG) is increasing day to day life due to their advantages of increasing system reliability and power quality. Ahead of their advantages, they are suff ering with the problem of unintentional islanding. Islanding is caused in the DG due to problems in the main grid. It is required to detect the islanding within 2 s after islanding as per DG interconnection standards. In this paper a new passive islanding detection method for single synchronous generator based DG and multiple DG units is proposed with rate of change of exciter voltage, over the rate of change of reactive power (dE/dQ). Due to inertia, the response of these exciter voltage and reactive power are very sensitive to small changes compared to other passive parameters, because in the real world the exciter voltage and reactive power are directly depends on the excitation of the generator. The investigations are made on the Matlab/Simulink environment. This method is clearly diff erentiating between islanding and non islanding events. The eff ectiveness of this method compared with other passive methods is, it detects islanding during zero power imbalance conditions of active and reactive power.
A Novel Active Current Disturbance Method Based on Discrete Wavelet Analysis
Wu Tiezhou,Xiong Jinlong,Wu Xiaomin,Luo Meng 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.12
Islanding detection method of active current disturbances in three-phase photovoltaic-to-grid system makes the common connection point (PCC) voltage appear high frequency components on account of load variation, the surge current occurrence and other factors. This high frequency component cause islands misjudgment. Using Db10 wavelet to detect and analysis PCC’s voltage high-frequency components on real-time based on the active current disturbances principle. And selecting an effective wavelet domain values as the voltage harmonic detection amount islanding detection. Islands simulation test is conducted in the case of the inverter output power and load input power to match, the test results show that this method can quickly detect islanding, and effectively prevent pseudo-island phenomenon of false positives.
Hybrid ROCOF Relay for Islanding Detection
Rami Reddy Ch.,Harinadha Reddy K.,Aymen Flah,Srikanth Goud B.,Bajaj M.,Abdulaal M. J.,Milyani A. H. 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.1
Distributed generation (DG) is increasing in day to day life to meet the global energy consumption demand. One of the major problems with such DG is islanding. The islanding is caused in the grid connected system when a part of DG is disconnected from the main grid and continues to feed the load connected. As per the IEEE 1547 DG interconnection standards, the islanding should be detected within 2 s after islanding. This paper presents, a new rate of change of frequency (ROCOF) based hybrid islanding detection approach. It combines the passive and active ROCOF methods. The simulation results indicate this method is very effi ciently classifying the islanding and non islanding events. It detects the zero power balanced islanding within 200 ms and unbalanced islanding within 100 ms. The simulation results are carried on Matlab/Simulink 2018B environment.
태양광 발전과 ESS 시스템의 연계운전시 단독운전 방지 사례 연구
임종록,황혜미,신우균,주영철,정영석,강기환,고석환 한국태양에너지학회 2019 한국태양에너지학회 논문집 Vol.39 No.1
The installation of BIPV or BAPV which is installed on building is increased in Korea, so that the cumulative installation has increased. However, the quality of power gird including distributed power sources such as PV system and wind power might degrade due to fluctuation of their output power by the source. As a solution to it, there is a method to connect PV system and ESS system. However, the ESS and PV system connected to grid in parallel can cause problems with electrical safety. This paper presents the results of case studies to detect islanding operation, which are electrical safety in situations that the photovoltaic system and ESS systems are connected in parallel to grid. The experiments were conducted under a various non-islanding detection in operating conditions. In the experiment result, when a individual inverter(PV inverter or ESS inverter) was operated under the islanding condition, it was stopped within 0.5 seconds on the Korean grid standard. However, when two inverters(PV inverter and ESS inverter) were operated at the same time in the islanding situation, the anti-islanding algorithm is not operated and two inverters continually supply the connected RLC load. So, the algorithm of islanding detection developed by each inverter manufacturer could cause this phenomenon. Therefore, the new test standard should be presented for islanding detection.
Yoshida, Yoshiaki,Fujiwara, Koji,Ishihara, Yoshiyuki,Suzuki, Hirokazu Journal of International Conference on Electrical 2014 Journal of international Conference on Electrical Vol.3 No.3
When large penetration of the distributed generators (DGs) such as photovoltaic (PV) systems is growing up in grid system, it is important to quickly prevent islanding caused by power system fault to ensure electrical safety. We propose a novel active method for islanding prevention by harmonic injection synchronized with the exciting current harmonics of the pole transformer to avoid mutual interference between active signals. We confirm the validity of the proposed method by performing the basic tests of islanding by using a current source superimposed the harmonic active signal. Further, we carry out the simulation using PSCAD/EMTDC, and verify the fast islanding detection.
Yoshida, Yoshiaki,Fujiwara, Koji,Ishihara, Yoshiyuki,Suzuki, Hirokazu The Korean Institute of Electrical Engineers 2013 The Journal of International Council on Electrical Vol.3 No.1
When distributed generators such as photovoltaic (PV) systems spread widely in distribution networks, it is important to detect islanding caused by power system fault for ensuring electrical safety. We developed the nonlinear magnetizing characteristics model of a pole transformer for analyzing islanding-prevention of PV system. Basic experiments of the islanding-detection were conducted by using the RLC resonant circuit for verification of the developed model. Analytical results by the proposed model agreed well with experimental results.
FRT Control Method Including Islanding Detection in PCS Model for Photovoltaic Generation
Miyazaki, Takahiro,Cheng, Wai Tatt,Yoshimura, Kazuaki,Taoka, Hisao,Kawasaki, Shoji,Matsuki, Junya The Korean Institute of Electrical Engineers 2013 The Journal of International Council on Electrical Vol.3 No.3
In this study, we made experiments by the simulated PV system for understanding the cause of disconnection when instantaneous voltage sag occurs. Moreover, it is understood that the PCS with the voltage phase jump detection method which is one of the main causes of the disconnection. We modeled it in the simulation. When fault occurs, even though the residual voltage is more than 20 % and the voltage sag time is within 1.0 sec, the PCS disconnected by the voltage phase jump detection was confirmed in the simulation results. If a large number of PV systems are interconnected in the power system, we verified through the simulation that the interaction caused by the disconnection which generated by the voltage phase jump detection. We proposed threshold limit value of islanding detection. The validity of proposed method was verified through the simulation in this study.
姜龍澈(Yong-Cheol Kang),車善熙(Sun-Hee Cha),張成一(Sung-Il Jang),姜海權(Hae-Gweon Kang),金容均(Yong-Gyun Kim),朴君哲(Goon-Cherl Park) 대한전기학회 2008 전기학회논문지 Vol.57 No.12
A large scale embedded generator or a micro-grid is usually interconnected to the grid through the dedicated line. Immediately after the removal of the grid supply, it must be disconnected and remain disconnected until the normal grid supplies are restored. This paper proposes an islanding detection algorithm based on complex power at the intertie. Complex power at the intertie delivered to the grid has a value depending on power flow during normal operation. When loss of mains occurs, complex power at the intertie moves to a value depending on the parameters of the dedicated line. The performance of the proposed algorithm was investigated under various operating and fault conditions. The proposed algorithm can detect an islanding operation even if no power is exchanged prior to loss of mains and discriminate the fault condition from islanding.