A Pattern-Recognition Approach for Detecting Power Islands Using Transient Signals—Part II: Performance Evaluation

Abstract

Part I of this paper describes the design and implementation of an islanding detection method based on transient signals. The proposed method utilizes discrete wavelet transform to extract features from transient current and voltage signals. A decision-tree classifier uses the energy content in the wavelet coefficients to distinguish islanding events from other transient generating events. The verification tests performed in Part I, for a two generator test system having a synchronous generator and a wind farm, showed more than 98% classification accuracy with 95% confidence and a response time of less than two cycles. In Part II, the proposed methodology is applied to an extended test system with a voltage-source converter-based dc source. The proposed relay's performance is compared with the existing passive islanding detection methods under different scenarios. Furthermore, the effect of noise on the performance of the proposed method is studied. The transient-based islanding detection methodology exhibits very high reliability and fast response compared to all other passive islanding detection methods and shows that the relay can be designed with a zero nondetection zone for a particular system.

Impact of Islanding Detection Time Duration on the Stable Operation of a Synchronous Generator Controlled Microgrid

“…Results reveal that over/under voltage relays take more than 600 ms while over/under frequency relays taking nearly 1 s to detect power islanding. It is concluded in [20] that both these relays present a larger non-detection zones as well. Fig.…”

“…4 Microgrid control changes involved upon disconnecting from the grid From Table 2 it shows that voltage vector shift relay takes less than 30 ms to detect power islanding. However, in [20] it has shown that voltage vector shift relays' reliability is less at lower settings and presents a higher non-detection zone at higher relay settings. Rate of change of frequency relay response times, which indicates to be above 150 ms, highly depends on the relay setting and power imbalance.…”

“…Passive islanding detection methods use these parameters to identify a power island. In [20], response times of different passive islanding detection relays are compared. Table 2 presents average detection times of different passive islanding detection relays for the 250 islanding events tested in [20] for the same power system shown in Fig.…”

“…Rate of change of frequency relay response times, which indicates to be above 150 ms, highly depends on the relay setting and power imbalance. In [20], it has shown that rate of change of frequency relay too has a considerable non-detection zone at higher settings while presenting low security at lower relay settings.…”

Anti-Islanding Protection of Distributed Generation Based on Social Spider Optimization Technique

“…The disturbances inserted in the distribution system may cause power quality deterioration. The passive method uses wavelet [5]. The wavelets extract voltage and current features and use a decision tree to identify the islanding.…”