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Table 5 Distinctive features of investigated signal processing-based protection schemes

From: Comparative framework for AC-microgrid protection schemes: challenges, solutions, real applications, and future trends

References

Year

Citation

DER

Required measures

Method

Features

[110]

2016

20

Synchronous and inverter based

Fault current

WT and decision tree

Twelve statistical features such as: mean, standard deviation, energy, entropy, etc., are extracted from fault current decomposition to train the decision tree

High impedance faults are detectable

Requires offline training, and high computational burden

[111]

2016

260

Inverter based

Actual and sequence components of fault current

WT and decision tree

Nine features are used for fault detection, while fifteen for fault classification

70% of input data are used for training, remaining 30% for testing

High computational burden due to required trainings

Low-impedance faults are only used for training

[112]

2021

10

Synchronous and inverter based

Voltage and current data

WT and random forest

Random forest is used as a data mining tool to accurately process a large input database, unlike the decision tree.

75% of input data are used for training, the remaining for testing

Considers DERs outages and fault initiation periods

Robust against measurement noise

Requires high capability software for training

[113]

2017

35

Synchronous and inverter based

Voltage or current data

WT and park’s transformation

The d-q voltages/currents feed wavelet model

Not preferable for high-impedance faults

High sampling frequency, and low accuracy

Large time response for data processing

Detection signal is delayed to distinguish false faults

[115]

2019

19

Not reported

Voltage and current waves

TWs

Fault is detected based on traveling waves polarities

Considers zero-sequence voltage to avoid false detection

Considers fault inception time, type, and resistance

Applicable for SLG faults in non-effectively grounded systems

[116]

2014

123

Inverter based

Fault current wave

TWs

Low-bandwidth communication is employed for high-speed operation

Stable during normal transients i.e. motor starting

Considers traveling wave amplitude, timing, and polarity for accurate detection

[117]

2017

5

Synchronous and inverter based

Local currents and fault current wave

TWs

Detect fault based on WT of the traveling wave, while zone classification relies on wave signs

Applicable for close-in faults

Stable during switching transients and external abnormalities

[121]

2022

2

Synchronous and inverter based

Currents at both ends of line

S-transform-based differential current

Varied threshold value with the operating mode and fault impedance, i.e. high impedance fault.

High impedance faults are detectable

Robust against measurement noise

[122]

2021

10

Inverter based

Current and voltage data

S-transform-based distance relay

Fault energy is used as a fault indicator, while distance relay defines trip timings.

Low computational burden

High impedance faults are addressed

[123]

2014

15

Synchronous and inverter based

Currents at both ends of line

S-transform and decision tree

Low computational burden

Fast response (1–1.5) cycle

Requires offline training

[126]

2021

8

Synchronous and inverter based

Currents at both ends of line

Hilbert–Huang transform

Low required time for fault detection and classification processes

Limited to fault impedance larger than 1000 Ω

Self-adaptive threshold: large in normal conditions and decreases with faults

[82]

2018

144

Synchronous and inverter based

Current measurements

Hilbert–Huang transform

Three distinctive differential features are used: phase current energy, standard deviation of phase current, and zero-sequence current energy

Applicable for high-impedance faults

Machine learning model uses 70% of input data for training, remaining 30% for testing

Offline training is needed

[127]

2008

120

Inverter based

Voltage data

Harmonic content-based

THD value is dependent on network configuration

Individual values of THD are used to classify fault type

Applicable only for identical DERs

High impedance faults are not investigated

[128]

2016

13

Inverter based

Harmonic current (5th harmonic)

Harmonic content-based

Inverter-based DER injects harmonic currents

Not applicable for high-impedance faults

Inaccurate in a harmonic rich system

[129]

2022

1

Inverter based

Multiple Harmonic components

Harmonic content-based

Multiple harmonics injection ameliorates sensitivity

Reliable and low-cost due to communication-free protocol

Injected harmonic component has a magnitude of 10% of fault current

Each inverter injects a distinct harmonic content

Detects high-impedance faults

[130]

2018

4

Inverter based

Voltage and current data

Harmonic current

Harmonic content-based

Optimized coordination settings using Particle Swarm Optimization

Only low-impedance faults are verified

Avoids resonance conditions when selecting the injected harmonic