A Novel Hybrid Islanding Detection Method for Inverter-Based DGs Using SFS and ROCOF

SUMMARY There is an abundant interest in microgrids due to its innate ability to operate in either utility connected or isolated mode. The existing conventional methods disconnect the individual distributed generators on loss of utility. In this work, a combined islanding detection algorithm at the point of common coupling (PCC) of the whole microgrid is proposed. It detects islanding using islanding detection monitoring factor, rate of change of inverse hyperbolic cosecant function, and voltage at the PCC as the islanding detection elements with the help of phasor measurement units. On detection of islanding event, the whole microgrid is transferred to autonomous mode. Moreover, any fault in the microgrid side which may isolate the distributed generator is detected using dilation and erosion mathematical morphological operators. The algorithm estimates the probability of power balance and probability of islanding duration at the control centre for events within the microgrid. The decision for islanded operation or disconnecting the distributed generator is communicated based on this. The proposed method is tested on a microgrid test system and verified on a section of the realistic local feeder of the Indian utility system. The simulation results indicate that the developed algorithm is quick, reliable, and secure in discriminating between the islanding and nonislanding scenarios for the various cases during both import and export conditions with an accuracy of 100%. It eliminates the nondetection zone completely even during zero power mismatch conditions. With the proposed method, any unnecessary distributed generator outage can be avoided enhancing the microgrid utilisation.

Section: Probability Of Power Balance and The State Of Probability mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A combined islanding detection algorithm for grid connected multiple microgrids for enhanced microgrid utilisation

Radhakrishnan

Ashok

Sunitha

2019

“…These methods are low priced to apply, and they have no disturbance in the power system, but their main downside is large NDZ . In the case that power inconformity between load and DGs is small, the voltage and frequency fluctuations at PCC will not go beyond the threshold, and a passive method fails to identify the islanded condition . In addition, other non‐islanding events such as any kind of transient faults can cause fluctuation in parameters and errors in the detection process.…”

Section: Introductionmentioning

confidence: 99%

“…Active methods are effective even when the power mismatch is small, but their disadvantages are poorer power quality and detection speed in comparison with passive methods. Some active methods introduced in the literatures are slip‐mode frequency shift (SMS), Sandia frequency shift (SFS), Sandia voltage shift method, and robust islanding algorithm …”

Section: Introductionmentioning

confidence: 99%

A hybrid islanding detection technique for inverter‐based distributed generator units

Seyedi

Taher

Ganji

et al. 2019

Summary Due to high importance of islanding detection as an essential protection requirement, especially for the distributed generation (DG), a new approach to islanding detection is developed in the present paper. The method is based on a mixture of both active and passive algorithms, which uses voltage phase angle (VPA) and voltage unbalance (VU). The suggested method presents a combination of benefits of each individual passive/active method, and therefore it is useful to appropriately detect islanding situation in a wide range of scenarios. The use of the suggested method results in smaller nondetection zone (NDZ), faster response, and improved power quality. In order to illustrate the effectiveness of this approach, simulation results are provided under different conditions, showing that the suggested algorithm can reach the required islanding protection requirements. In addition, the performance of the proposed method and some other methods are compared by the presence of a variety of transient faults and insignificant power mismatch.

Single‐phase reclosing technique for reducing islanding events of distributed generators during temporary faults

Milošević

Đurišić

2019

Summary Integration of renewable energy sources into a distribution system requires adjustments and improvement of the existing relay protection systems. Application of the three‐phase reclosing in radial distribution networks often leads to the island operation of the distributed power generation, which causes the generator's disconnection from the network. The application of the upgraded single‐phase reclosing technique, which is proposed in this paper, enables a partial transfer of energy into the electric power system during the temporary fault. Thus, it contributes to the maintenance of the distributed generator transient stability during temporary faults in the distribution network. Improvement of single‐phase reclosing technique is reflected in the adaptation to eliminate various types of faults that may occur. The analyses include different operation conditions and stability requirements of distributed generators. The proposed solution is presented in the paper by example of different types of distributed generation: a small hydropower plant with a synchronous generator that is directly connected to the distribution network, and a wind power plant with double fed induction generator and photovoltaic systems. The results of the analyses are presented in the form of dynamic simulations performed by DIgSILENT PowerFactory software using IEEE 33‐bus model of distribution network.