Microgrid Protection Strategy Based on the Autocorrelation of Current Envelopes Using the Squaring and Low-Pass Filtering Method

To resolve the protection issues caused by high penetration of distributed energy resources, this paper proposes an efficient protection scheme for microgrids based on the autocorrelation of three-phase current envelopes. The proposed strategy uses a squaring and low-pass filtering approach for evaluating the envelope of the current signal. Then, the variance of the autocorrelation function is used to extract the hidden information of the distorted envelope to detect the fault signatures in the microgrid. Furthermore, the reactive power is used for determining the fault direction. The performance of the proposed protection scheme was verified on a standard medium-voltage microgrid by performing simulations in the MATLAB/Simulink environment (Version: R2017b). The proposed scheme was shown to be easy to implement and have good performance under looped and radial configuration for both grid-connected and islanded operation modes. The simulation results showed that the scheme could not only detect, locate, classify, and isolate various types of short-circuit faults effectively but also provide backup protection in case of primary protection failure.

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Advance Protection for Three Phase Induction Motor using Microcontroller Atmega32

International Journal of Advanced Research in Computer Science and Software Engineering ◽

10.23956/ijarcsse.v8i1.566 ◽

2018 ◽

Vol 8 (1) ◽

pp. 172

Author(s):

Karan S Belsare ◽

Gajanan D Patil

Keyword(s):

Induction Motor ◽

Low Cost ◽

Short Circuit ◽

Cost Factor ◽

Protection Scheme ◽

Three Phase ◽

The Cost

A low cost and reliable protection scheme has been designed for a three phase induction motor against unbalance voltages, under voltage, over voltage, short circuit and overheating protection. Taking the cost factor into consideration the design has been proposed using microcontroller Atmega32, MOSFETs, relays, small CTs and PTs. However the sensitivity of the protection scheme has been not compromised. The design has been tested online in the laboratory for small motors and the same can be implemented for larger motors by replacing the i-v converters and relays of suitable ratings.

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Research on Transient Power Quality of Large-capacity Electric Arc Furnace

10.20944/preprints202103.0305.v1 ◽

2021 ◽

Author(s):

Liu Yang ◽

Qinyue Tan ◽

Di Xiong ◽

Zhengguang Liu

Keyword(s):

Power Quality ◽

Reactive Power ◽

Short Circuit ◽

Electric Arc Furnace ◽

Electric Arc ◽

Normal Operation ◽

Arc Furnace ◽

Three Phase ◽

Transient Power Quality

The overrun of transient power quality index caused by the large-capacity electric arc furnace (EAF) has become a prominent problem affecting the safe and stable operation of the power system. (1) In this paper, the relationship between arc furnace volt-age and current is derived based on the different stages of arc combustion, and the random variation of chaotic phenomenon of the arc voltage are simulated. Established an EAF model suitable for the study of transient power quality problems. (2) Take 50t AC EAF as an example to analyze the reactive power impact and the influence on the point of common coupling (PCC) voltage caused by the three-phase short circuit of the electrode. The results show that the experimental results are consistent with the theoretical analysis, verifying the correctness and effectiveness of the model. (3) When the three-phase short-circuit occurs, the reactive power impact is nearly 6 times that of normal operation, the short-circuit current is 2.66 times that of normal operation, and the effective value of the PCC voltage has dropped by 40.37%, which provides a theoretical basis for real-time compensation of impulsive reactive power and improvement of the transient power quality of the EAF.

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A Novel Multilevel DC-Link Three-Phase T-Type Inverter

Energies ◽

10.3390/en13164186 ◽

2020 ◽

Vol 13 (16) ◽

pp. 4186

Author(s):

Saddam Shueai Alnamer ◽

Saad Mekhilef ◽

Hazlie Mokhlis ◽

Nadia M. L. Tan

Keyword(s):

High Efficiency ◽

Short Circuit ◽

Multilevel Converters ◽

Passive Components ◽

Medium Voltage ◽

Three Phase ◽

Unbalanced Voltage ◽

Flying Capacitors ◽

Voltage Deviation ◽

Current Commutation

This research proposes a four-level T-type inverter that is suitable for low-power applications. The presented topology outranks other types of inverters in terms of a smaller number of semiconductor devices, absence of passive components such as clamping diodes and flying capacitors, low switching and conduction losses, and high efficiency. The proposed topology is free from voltage deviation and unbalanced voltage occurrences that are present in other multilevel converters having clamping diodes or flying capacitors. The proposed inverter can extend to N levels using unequal dc-link voltage sources for medium-voltage application. The inverter employs the simple fundamental frequency staircase modulation technique. Moreover, this paper presents a current commutation strategy to prevent the occurrences of short circuit and minimizing the number of required switching devices and switching transitions, resulting in improving the efficiency of the inverter. This paper also analyses the theoretical converter losses showing lower switching and conduction losses when compared to existing four-level inverters. The experimental validation of the proposed inverter shows its operating feasibility and a low output voltage THD.

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Use of the Particle Swarm Technique to Optimize Parameters of Photovoltaic Generators on Networks with High Integration of Distributed Generation

10.48011/sbse.v1i1.2301 ◽

2020 ◽

Author(s):

Luiz G. R. Tonini ◽

Felipe Z. da Silva ◽

Renato S. F. Ferraz ◽

Oureste E. Batista ◽

Augusto C. Rueda-Medina

Keyword(s):

Distributed Generation ◽

Reactive Power ◽

Short Circuit ◽

Short Circuit Current ◽

Energy Sources ◽

High Penetration ◽

Power Injection ◽

Major Disruption ◽

Electricity Power ◽

Photovoltaic Generators

In search of greater diversity in energy sources, to meet the demand of the electricity power, the use of photovoltaic generators is increasing. Such components have their power generation specified by IEEE 1547/2018, which limits the power parameters of each one. In a situation of high penetration of distributed generation, generators can contribute to the electric current that will circulate within the system in case of a fault, causing major disruption to the mesh and the users. Seeking to reduce this impact, the paper will minimize the value of the short circuit current by adjusting the parameters of the photovoltaic generators. The analysis will be done on IEEE Test Feeder 13 and 34 nodes and will refer to generators from category A, B and without reactive power injection in the mesh.

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Faulty Synchronization of Salient Pole Synchronous Hydro Generator

Energies ◽

10.3390/en13205491 ◽

2020 ◽

Vol 13 (20) ◽

pp. 5491

Author(s):

Adam Gozdowiak

Keyword(s):

Phase Shift ◽

Reactive Power ◽

Short Circuit ◽

Full Range ◽

Point Of View ◽

System Stability ◽

Salient Pole ◽

Three Phase ◽

Voltage Phase ◽

Physical Quantities

This article presents the simulation results of hydro generator faulty synchronization during connection to the grid for various voltage phase shift changes in a full range (−180°; 180°). A field-circuit model of salient pole synchronous hydro generator was used to perform the calculation results. It was verified using the measured no-load and three-phase short-circuit characteristics. This model allowed observing the physical phenomena existing in the investigated machine, especially in the rotor which was hardly accessible for measurement. The presented analysis shows the influence of faulty synchronization on the power system stability and the construction components which are the most vulnerable to damage. From a mechanical point of view, the most dangerous case was for the voltage phase shift equal to −120°, and this case was analyzed in detail. Great emphasis was placed on the following physical quantities: electromagnetic torque, stator current, stator voltage, rotor current, current in rotor bars, and active and reactive power. The physical quantities existing during faulty synchronization were compared with a three-phase sudden short-circuit state. From this comparison, we selected the values of physical quantities that should be taken into account during design of new hydro generators to withstand the greatest possible threats during long-term work.

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Differential method for damage location determining in 10 kV distribution networks with isolated neutral

E3S Web of Conferences ◽

10.1051/e3sconf/201912401003 ◽

2019 ◽

Vol 124 ◽

pp. 01003

Author(s):

V. Kozlov ◽

E. Kirzhatskikh ◽

R. Giniatullin

Keyword(s):

Transmission Lines ◽

Short Circuit ◽

Distribution Networks ◽

Differential Method ◽

Medium Voltage ◽

Damage Location ◽

Damage Repair ◽

Three Phase ◽

Isolated Neutral ◽

Emergency Mode

Half of the length of all transmission lines (TL) are medium voltage networks. Single-line-to-ground short circuit (SLGSC) in distribution networks is the most common type of damage, accounting up to 70% of all types of damage. Faults in damage repair leads to an overvoltage of two healthy phases, resulting in double shorts, two-, three-phase shorts, which contributes to consumers’ disconnection. Remote damage location (DL) determination in tree-type networks is considered to be the most relevant, since these networks are spread over large areas, crossing rivers, ravines, lakes, forests, etc. This paper presents a differential method for DL determining based on steady-state voltage of damaged phase frequency. Measuring the parameters of emergency mode at the beginning and at the ends of 10kV TL allows compact stand-alone sensors using without their synchronization.

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Efficient Protection Scheme Based on Y-Source Circuit Breaker in Bi-Directional Zones for MVDC Micro-Grids

Inventions ◽

10.3390/inventions6010018 ◽

2021 ◽

Vol 6 (1) ◽

pp. 18

Author(s):

Haider Al-khafaf ◽

Johnson Asumadu

Keyword(s):

Power Flow ◽

Circuit Breaker ◽

Magnetic Coupling ◽

Medium Voltage ◽

Protection Scheme ◽

Fault Type ◽

Source Impedance ◽

Source Current ◽

Efficient Protection ◽

Micro Grids

A new bi-directional circuit breaker is presented for medium-voltage dc (MVDC) systems. The Y-source impedance network topology is used to implement the breaker. The current transfer function is derived to show the frequency response and the breaker operation with the high frequencies. Mathematical analysis is achieved with different conditions of coupling among the breaker inductors. The minimum level of the magnetic coupling is determined, which is represented by the null condition. The effect of the turns-ratio on this condition is investigated as well. The breaker is designed with two types of fault conductance slope rates. The Y-source breaker is simulated, and the results verify the breaker operation during the fault condition and the load change. The results also demonstrate the effect of the coupling level on the minimum values of the source current when the fault occurs. Based on the expected fault type in the MVDC systems, the proposed breaker is developed to interrupt the overcurrent due to any of these fault types. A protection scheme is proposed for a 12-bus, two-level micro-grid, where the Y-source breakers are used in the bi-directional zones. The results verify the ability of the breaker to conduct and interrupt the current in both directions of the power flow.

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Detection for Rective Current Based on the Instantaneous Reactive Power Theory

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.433-440.6565 ◽

2012 ◽

Vol 433-440 ◽

pp. 6565-6571

Author(s):

Xiao Cui Lei ◽

Guang Zeng ◽

Jing Gang Zhang

Keyword(s):

Single Phase ◽

Reactive Power ◽

Phase Locked Loop ◽

Pass Filter ◽

Low Pass Filter ◽

Power Theory ◽

Instantaneous Reactive Power Theory ◽

Three Phase ◽

Reactive Current ◽

Low Pass

Three-phase circuit instantaneous reactive power theory has received a successful application in detecting harmonic and reactive current timely, the ip-iq and d-q method of first proposed require the phase-locked loop and low-pass filter. The paper make corresponding improvement on the basis of the method based on amplitude integration which only can detect fundamental current , propose a method which can detect the active and reactive current, and the method based on amplitude integration can detect fundamental current of single-phase circuit directly, and simulation. The simulation results show that the method can detect the harmonic and reactive current accurately and timely, and is suitable for various circumstances that three-phase power supply distortion and asymmetry and so on, and when only detecting the harmonic current, it does not require the phase-locked loop and low-pass filter, while detecting the harmonic and reactive current, increases the phase-locked loop; when the method based on amplitude integration is directly used to detect single-phase fundamental current, the phase-locked loop and low-pass filter are not required. The paper deduces the theory of the method and researches on simulation analysis.

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OPF-based Active Network Management Strategy for Distribution Networks with High Penetration of Distributed Generation

10.48011/sbse.v1i1.2490 ◽

2020 ◽

Author(s):

Celso Rocha ◽

Paulo Radatz ◽

Carlos Almeida ◽

Nelson Kagan

Keyword(s):

Network Management ◽

Distributed Generation ◽

Power Flow ◽

Low Voltage ◽

Distribution Networks ◽

Active Network ◽

Medium Voltage ◽

Pv Systems ◽

High Penetration ◽

Three Phase

This paper presents a near real-time strategy for Active Network Management (ANM) considering distribution networks with high penetration of Distributed Generation (DG). It is built upon a centralized framework and availability of a broad communication infrastructure. Generation curtailment level of Medium Voltage (MV), residential and commercial-scale Photovoltaic (PV) systems are considered as control variables to manage voltage and asset loading levels in MV and Low-Voltage (LV) distribution networks through a three-phase unbalanced Non-Linear (NL) Optimum Power Flow (OPF) algorithm. The effectiveness of the strategy in maintaining the regulatory operational levels, its robustness and the effect of the processing and communication delays are assessed by simulating a real Brazilian network with 788 control elements.

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