What is islanding ?
Consider the power network as shown in fig.1
Now if we disconnect the line AB from the infinite transmission grid there will be an isolated region . The D1, D2 are power sources (eg : inverter , solar power cells ). The power generated in this region is fed to the island only.
We see that there no longer is any control over the island voltage at the bus X . Also there is no mechanism here for control of frequency.
This state is referred to as islanding.
This slide presents an introduction to microgrid. This is the second class for the subject 'Distribution Generation and Smart Grid'. Class wise I will provide all the discussions and analysis.
These slides present about islanding detection techniques in microgrid systems. Later on the classes other aspects of microgrid protection will be discussed in more detail
Types of islands in power systems with DR
Issues with unintentional islands
Methods of protecting against unintentional islands
Standard testing for unintentional islanding
Advanced testing of inverters for anti-islanding functionality
Probability of unintentional islanding
The future of anti-islanding protection
This slide presents an introduction to microgrid. This is the second class for the subject 'Distribution Generation and Smart Grid'. Class wise I will provide all the discussions and analysis.
These slides present about islanding detection techniques in microgrid systems. Later on the classes other aspects of microgrid protection will be discussed in more detail
Types of islands in power systems with DR
Issues with unintentional islands
Methods of protecting against unintentional islands
Standard testing for unintentional islanding
Advanced testing of inverters for anti-islanding functionality
Probability of unintentional islanding
The future of anti-islanding protection
These slides presents the different challenges and issues related to DG integration to Micro-grid distribution systems. The possible solutions are also presented. Later of the class I will try to upload the mathematical presentations and simulation results related to each protection scheme. However, your suggestions are always welcome.
Load / Frequency balancing Control systems studyCAL
In this project, the load and frequency control problem on the power generator at 'Britannia sugar factory' is investigated under different governor action. The existing system employs a Mechanical-hydraulic governor. It is desired to improve the system's response to load disturbances on the interconnected power grid.
The solar energy is converted to electrical energy by photo-voltaic cells. This energy is stored in batteries during day time for utilizing the same during night time. A charge controller, or charge regulator is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panels going to the battery.
The electric power supplied by a photovoltaic power generation system depends on the solar radiation and temperature. Designing efficient PV systems heavily emphasizes to track the maximum power operating point.
This work develops a three-point weight comparison method that avoids the oscillation problem of the perturbation and observation algorithm which is often employed to track the maximum power point. Furthermore, a low cost control unit is developed, based on a single chip to adjust the output voltage of the solar cell array.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
These slides presents the different challenges and issues related to DG integration to Micro-grid distribution systems. The possible solutions are also presented. Later of the class I will try to upload the mathematical presentations and simulation results related to each protection scheme. However, your suggestions are always welcome.
Load / Frequency balancing Control systems studyCAL
In this project, the load and frequency control problem on the power generator at 'Britannia sugar factory' is investigated under different governor action. The existing system employs a Mechanical-hydraulic governor. It is desired to improve the system's response to load disturbances on the interconnected power grid.
The solar energy is converted to electrical energy by photo-voltaic cells. This energy is stored in batteries during day time for utilizing the same during night time. A charge controller, or charge regulator is basically a voltage and/or current regulator to keep batteries from overcharging. It regulates the voltage and current coming from the solar panels going to the battery.
The electric power supplied by a photovoltaic power generation system depends on the solar radiation and temperature. Designing efficient PV systems heavily emphasizes to track the maximum power operating point.
This work develops a three-point weight comparison method that avoids the oscillation problem of the perturbation and observation algorithm which is often employed to track the maximum power point. Furthermore, a low cost control unit is developed, based on a single chip to adjust the output voltage of the solar cell array.
International Journal of Engineering Research and DevelopmentIJERD Editor
Electrical, Electronics and Computer Engineering,
Information Engineering and Technology,
Mechanical, Industrial and Manufacturing Engineering,
Automation and Mechatronics Engineering,
Material and Chemical Engineering,
Civil and Architecture Engineering,
Biotechnology and Bio Engineering,
Environmental Engineering,
Petroleum and Mining Engineering,
Marine and Agriculture engineering,
Aerospace Engineering.
Hysteresis SVM for Coupled Inductor Z Source Diode Clamped 3-Level Inverter B...IAES-IJPEDS
Due to its advantages such as it can defeat problems such as leakage current
and insertion of DC in the grid and provides low stress on power devices,
Diode-clamped three-level inverter (DCTLI) is habitually used in
transformerless photovoltaic (PV) connected to grid network. But it still has
a problem of shoot-through which dwells in its legs, so its operation not
reliable. Z source network is employed to permit operation without shoot
through risk and improve its reliability. Coupled inductors are replaced the
line transformers in to attain lower cost, reduced size, and improved its
reliability and efficiency. Coupled inductor which avoids leakage current
problem and losses. It employs coupled inductor z source diode clamped
three level inverter (CI-Z-DC-TLI) to boost the voltage and further progress
the consistency of the proposed system by avoiding the shoot through the
problem. The proposed system assures that common-mode voltage
and shoot-through risk is avoided. Moreover, controlling DC-TLI with
Hysteresis SVM algorithm which improves output voltage and current
control. Simulation and experimental results of this proposed system were
analyzed using MATLAB environment and FPGA hardware.
Design of Soft Switching Converter with Digital Signal Processor Based MPPT f...IDES Editor
This paper is based on the design of soft
switching converter (ZVS-ZCS resonant action) with
digital signal processor (DSP) based maximum power
point tracking (MPPT) algorithm for solar hybrid
applications. The converter aims to get the regulated
output voltage from several power sources like wind
turbines, photovoltaic (PV) arrays and energy from these
sources are simultaneously transferred to the load. The
input stage circuits for different energy sources are put in
parallel using a coupled inductor and the converter to
prevent power coupling effect it acts in interleaving
operating mode. As the buck/boost converter input range
is restricted interleaved ZVS-ZCS converter with low
switching loss and conduction loss and efficiency of more
than 92% can be easily achieved. DSP based MPPT
algorithm adjusts solar array voltage (equal to battery
voltage) with a digital compensator technique and
discrete PI control to track the MPP with high tracking
efficiency. Hence the proposed work gives a novel idea in
the modern hybrid energy system.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Performance analysis of active clamped interleaved fly-back inverter for phot...eSAT Journals
Abstract
A new control strategy has been proposed for the interleaved flyback inverter. the proposed method consists of two control strategies,
they are active clamp control and phase control. Based on the output power of the PV module each converter phase of an ILFI i s
controlled. due to the active clamp control method the energy in the leakage inductance can be fully recycled. the concept of
interleaving reduces the ripple and reduces the usage of capacitors. The induction motor drive has been used the speed performance
of the drive has been analyzed .simulations are done using MATLAB. The parameters are analyzed without PV and with PV. The
explanations, theories and results are discussed further.
Keywords- interleaved flyback inverter, active clamp, photovoltaic, induction motor drive
A Flexible AC Distribution System for a Microgrid with a Photovoltaic System ...IJMTST Journal
This paper presents a FACT ac distribution system device for micro grid applications. The device aims to improve the power quality and reliability of the overall power distribution system that the micro grid is connected to. The control design employs a new model predictive control algorithm which allows faster computational time for large power systems by optimizing the steady-state and the transient control problems separately. Extended Kalman filters are also employed for frequency tracking and to extract the harmonic spectra of the grid voltage and the load currents in the micro grid. Simulation results is verified through different case studies.
Grid tied photovoltaic (PV) system is an operation mode of PV system working together with utility power supply to provide power to the power load. Conventionally, transformer is used together with the power inverter. The power transformer works as galvanic insolation amongst PV system and power grid. It works also to raise the voltage of power inverter. However, use of transformer will add system complexity, price, weight and size of the entire system. Transformer-less system is an alternative to make the system simpler and more practical in use. The paper discusses performance of transformer-less grid tied PV systems using diode clamped and neutral point shorted inverters. Effects of transformer elimination to the feat of the grid tied PV system especially harmonics content and leakage current of PV system were examined and analyzed. The performance was also compared with the traditional system using H-bridge inverter. The leakage currents did not flow in the system applying diode clamped inverter, and neutral point shorted inverter. In case of harmonics content, the diode clamped inverter injected less harmonics components than the neutral point shorted inverter. The neutral point shorted provides a simpler inverter circuit in the transformerless systems.
This paper describes the Grid connected solar photovoltaique system using DC-DC boost converter and the DC/AC inverter (VSC) to supplies electric power to the utility grid. The model contains a representation of the main components of the system that are two solar arrays of 100 kW, boost converter and the grid side inverter. The paper starts with a system description, in this part we have given a definition and a short overview of every component used in this system and they are taken separately. The PV cell model is easy, accurate, and takes external temperature and solar radiation into consideration. It also proposes a maximum power point tracking (MPPT) algorithm. The algorithm incorporated in a DC/DC converter is used to track the maximum power of PV cell. Finally, the DC/AC inverter (VSC) of three- level is used to regulate the ouput voltage of DC/DC converter and connects the PV cell to the grid. Simulation results show how a solar radiation’s change can affect the power output of any PV system, also they show the control performance and dynamic behavior of the grid connected photovoltaic system.
Power Quality Improvement with Multilevel Inverter Based IPQC for MicrogridIJMTST Journal
A micro grid is a hybrid power system consists of several distributed resources and local loads .Now a
days with increasing on a day to day life micro grid plays a vital role in power generation using Renewable
Energy Sources. Usage of power electronic devices in a micro grid results in harmonic generation and leads to
various power quality issues. Inorder to overcome voltage fluctuations and over current a magnetic flux
control based variable reactor is proposed. The performance of IPQC can be verified by using
MATLAB/SIMULINK`
Filter Based Solar Power Generation System with a Seven Level InverterIJMTST Journal
This paper proposes a new solar power generation system, which is composed of a DC/DC power converter and a new seven-level inverter. The DC/DC power converter integrates a DC-DC boost converter and a transformer to convert the output voltage of the solar cell array into two independent voltage sources with multiple relationships. This new seven-level inverter is configured using a capacitor selection circuit and a full-bridge power converter, connected in cascade. The capacitor selection circuit converts the two output voltage sources of DC-DC power converter into a three-level DC voltage and the full- bridge power converter further converts this three- level DC voltage into a seven-level AC voltage. In this way, the proposed solar power generation system generates a sinusoidal output current that is in phase with the utility voltage and is fed into the utility. The salient features of the proposed seven-level inverter are that only six power electronic switches are used and only one power electronic switch is switched at high frequency at any time. A prototype is developed and tested to verify the performance of this proposed solar power generation system.
Implementation Of A High-Efficiency, High-Lifetime, And Low-Cost Converter Us...irjes
This paper proposes a new converter for photovoltaic water pumping and treatment systems without
the use of storage elements. The converter is designed to drive a three-phase induction motor directly from PV
solar energy. The use of this motor has the objective of presenting a better solution to the standard DC motor
water pumping system. The development is oriented to achieve a commercially viable solution and a market
friendly product. The converter topology is based on a Resonant Two Inductor Boost converter and a Threephase
Voltage Source inverter achieving 90% efficiency at a rated power of 210W.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
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Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
2. INTRODUCTION
What is islanding ?
Consider the power network as shown in fig.1
• Now if we disconnect the line AB from
the infinite transmission grid there will be
an isolated region . The D1, D2 are power
sources (eg : inverter , solar power cells ).
The power generated in this region is fed
to the island only.
• We see that there no longer is any control
over the island voltage at the bus X . Also
there is no mechanism here for control of
frequency.
• This state is referred to as islanding.
3. PAPERS
PAPER-1: Prevention of Islanding in Grid Connected PV System Using Twelve
Pulse Line.
AUTHORS: 1. Dhanshree A. Diyewar
2. Jyoti M. Kumbhare
PAPER-2 : Micro-grid Islanding Detection Based on PQ Active method.
AUTHORS: 1. Zhu Yipeng
2.Teng Yun
4. PAPER.1
PREVENTION OF ISLANDING IN GRID CONNECTED PV
SYSTEM USING TWELVE PULSE LINE.
Outline :
• Abstract
• Introduction
• 12-Pulse Line commutated converter (LCC)
• Proposed Scheme
• Photovoltaic Characteristics
• Simulation results
• Conclusion
5. ABSTRACT
One of the major drawback of connecting PV systems to the grid is unintentional
islanding condition.
Islanding can be dangerous for utility workers and damage utility equipment so
anti islanding is a crucial subject for grid connected PV systems.
For this reason inverter in the PV system must detect islanding and stop supplying
power if the grid is down.
In this paper 12 pulse LCC is used in inversion mode for the grid connection of PV
system.
A 12 pulse LCC converter needs commutating voltage of grid to operate.
The LCC do not require maintaining synchronism between grid and converter and
having an ability to suppress all harmonics below 11 th order.
The simulation results is carried out in Matlab/Simulink.
6. INTRODUCTION
PV generation have been come into prominence all over the world.
Solar energy is the most developed energy sources and is receiving wide attention
now a days because the everlasting solar energy is the best alternative to
conventional energy sources.
Grid connected PV systems is well recognized all over the world despite the fact
that there have been some drawbacks about connecting them to the electrical grid.
One of the major drawback of connecting PV systems to the grid is unintentional
islanding condition.
Islanding can be dangerous for utility workers and damage utility equipment so anti
islanding is a important subject for grid connected PV systems.
Islanding detection methods
1. Active methods
2. Passive methods
7. Passive methods Active methods
Based on measurement of the natural
effects of islanding
The active methods use intentional
transients or harmonic effects
passive methods fail due to the small
natural effects of islanding.
The passive methods have a non
detection zone (NDZ).
The active methods can reduce the NDZ
size. However, these methods reduce the
grid power quality
Many islanding detection algorithm based on VSI inverter based PV- grid interfacing .
For high power conversion line commutated converter (LCC) is widely used.
In HVDC at receiving end LCC operate in an inversion mode.
Commutation of thyristor takes place due to ac grid voltage LCC based grid connected PV
system does not require extra synchronizing controller like VSI when connected to ac grid.
8. LINE COMMUTATED CONVERTER
(LCC)
In this paper, twelve pulse LCC operates in an inversion mode for a firing angle greater than
90°.
Twelve pulse LCC is capable of suppressing all harmonics below 11 th order which improves
power quality of the grid.
Twelve pulse LCC has come into anti-islanding feature since islanded operation will not
occur as the converter needs commutating voltage of grid to operate.
The configuration of proposed scheme is shown in fig. 1
Fig. 1. Grid connected PV system using twelve pulse line commutated inverter for islanding prevention
9. In a twelve pulse LCC, two six pulse
converter is connected in series.
There is a phase difference of 30°.
It is obtained by lower bridge lags that
of upper by 30°.
The upper bridge connected through
star-star transformer and lower bridge
through star-delta transformer.
LINE COMMUTATED CONVERTER
(LCC)
Fig. 2. Twelve pulse line commutated converter
10. PROPOSED SCHEME
Figure 1 shows, the schematic of proposed scheme for grid connected PV system
using twelve pulse line commutated inverter.
PV system is connected to grid through twelve pulse line commutated inverter
with transformer and breaker.
PV generates dc and using inverter it convert in to ac and fed to the grid. The dc
source must be connected such that positive polarity is connected to the common
anode of the bridge and negative polarity is connected to the common cathode so
that power is transfer from the DC to AC side and converter operates in an inverter
mode by making firing angle greater than 90°.
If islanding condition is occur then photovoltaic system continues to energies the
load after the system has been disconnected from the grid. In islanding condition
twelve pulse LCC in PV system will not operate and stop supplying power to the
load.
11. PHOTOVOLTAIC CHARACTERISTICS
In the proposed scheme PV is
connected to LCC.
For the operation of converter as
inverter the DC voltage must be
greater than the supply voltage then in
that condition power is transfer from
dc side to ac side and converter
operates in inversion mode.
For this purpose PV voltage is 1000V
and supply voltage is 400V. The
simulation result of PV characteristic
is shown in Fig.3.
Boost voltage of dc-dc converter is
1000V which is applied to LCC.
Fig. 3. Photovoltaic array voltage
12. SIMULATION RESULTS
Fig. 4. Waveform of twelve pulse LCC for
150 degree
Fig. 5. Grid side current at 33 kV
The nature of current wave is almost square wave contains harmonics from 11 th order
and above which can be eliminated using filters.
13. SIMULATION RESULTS
In proposed scheme, simulation is done by considering islanding during 0.5 to 0.8
seconds. The islanding is shown in Fig. 6, from 0.5 to 0.8 seconds for which 33 kV
grid voltage is zero.
Fig. 6. Voltage during islanding condition at 33 kV Grid side
14. SIMULATION RESULTS
Fig. 7. Voltage of transformer across 440 V side Fig. 8. Dc link voltage of twelve pulse LCC during
islanding
15. CONCLUSION
In this paper, islanding is prevented using twelve pulse LCC.
During islanding dc link voltage of twelve pulse LCC is zero thus converter will
not operate and will not supply to any local loads and workers working on
converter side is prevented due to dangerous hazards.
One major advantage of LCC is, it does not require any synchronizing circuits and
is robust topology for high power application
16. REFERENCES
I. John K. Pedersen and Soeren Baekhoej Kjaer, "A Review of SinglePhase Grid-
Connected Inverters for Photovoltaic Modules" iEEE Transactions On industry
Applications, vol. 41 ,no. 5, SEP/OCT 2005,
II. T. R. Sims, R. A. Jones and A. F. Imece, 'Investigation of potential islanding
problems of a line-commutated static power converter in photovoltaic systems',
iEEE Tr
III. S. Samerchur, S. Premrudeepreechacharn Y. Kumsuwun, and K. Higuchi , "Power
Control of Single-PhaseVoltage Source Inverter for Grid-Connected Photovoltaic
Systems", iEEE , pp. 01,2011
IV. C.Boonmee and Y. Kumsuwan, "Modified Maximum Power Point Tracking
Based-on Ripple Correlation Control Application for SinglePhase VSI Grid-
Connected PV Systems", IEEE. Department of Electrical Engineering, pp. 01,
2013. [ansactions on Energy Conversion" , pp. 429-435.1990
17. PAPER.2
MICRO-GRID ISLANDING DETECTION BASED ON
PQ ACTIVE METHOD.
Outline :
• Abstract
• Introduction
• Islanding Detection Method
• Inverter modeling
• Relationship of Frequency with Islanding Operation
• Simulation results
• Conclusion
18. ABSTRACT
Micro-grids are being developed as a building block for future smart grid system.
Islanding detection is a great challenge in connecting distributed generation (DG)
in electrical power systems.
Islanding detection methods are categorized into two groups, i.e., communication
based methods, active, and passive methods.
Communication based methods are established upon communication between
utilities and DGs and have the inconvenience of being expensive and are limited in
use.
Active methods perturb the system with a disturbance and the system response to
the disturbance is analyzed.
This detection circuit model of the micro-grid islanding is simulated by the
software of MATLAB/Simulink, and the simulation results show that the islanding
detection method does achieve the effect of the micro-grid islanding detection.
19. INTRODUCTION
Renewable energy and the development of green power has become a hot topic in
the field of electrical .
With the increasing penetration of renewable energy and the application of large
area, the concentration of power production in the form of more decentralized
development.
Therefore, the micro network as a part of the main network, provides a lot of
auxiliary services to network.
It is a difficult task to guarantee the stability and reliability of micro grid, especially
in the isolated island mode.
The micro-grid is aimed to provide electricity for small communities (buildings,
schools, industry), which is a small scale grid.
The fossil fuels (diesel, gas turbine) and renewable energy (photovoltaic, wind
turbine) is its main source of electricity.
The micro grid architecture is shown in Fig.1.The power is supplied by DG.
20. Distributed storage systems store energy when they produce more than they
consume, and provide energy when consumption is greater than production.
In the micro-grid, the consumer of power is the load.
Electrical connection between the micro grid and the main power grid through the
point of common coupling (PCC).
Islanding is a major issue in penetration of DGs in the power system . Equivalent
islands Circuit is shown in Fig. 2.
Fig. 1 Architecture of a micro-grid
Fig. 2 Equivalent Islands Circuit
21. the islanding condition happens when “a portion of the utility system that contains
both load and distributed resources remains energized while it is isolated from the
remainder of the utility system”.
Unintentional islanding may lead to adverse consequences such as uncoordinated
protection, inadequate grounding, and safety aspects.
Current standards such as IEEE 929-1988 and IEEE 1547-2003 requires the
disconnection of the DG immediately and with delay of 2 seconds, respectively.
If the DG is allowed to work autonomously , fast islanding detection is required to
make appropriate decisions to control the DG in the autonomous mode.
Hence, detecting islanding correctly and as fast as possible is essential in
connecting DGs to the utility system.
22. ISLANDING DETECTION METHODS
Islanding detection methods can be divided
into two main groups.
(1) DG resident techniques
(2) Communication based techniques
Communication based methods : These
methods are based on communication
between the DG and the utilities.
These methods have a zero Non Detection
Zone (NDZ) but due to their high costs are
rarely used .
Islands Circuit is shown in Fig. 3.
DG resident methods: (a) Passive
(b) Active
(c) Hybrid methods
Fig. 3 Islands Circuit
23. (a). Passive methods
In passive methods certain system parameters such as frequency, voltage, phase angle, and
total harmonic distortion are monitored continuously and islanding detection is performed
from the variation of these parameters
The main drawback of these techniques is their large NDZ.
Particularly, when the power which the DG generates is equal to the power absorbed by the
loads, no power is exchanged between the grid and the DG.
The grid parameter changes are negligible and may not be detected by the islanding detection
technique.
(b). Active methods
Active techniques reduce the NDZ of passive methods.
These techniques perturb the system with a periodic or transient disturbance and estimate the
systems response to detect islanding.
24. In one way, active methods could be classified in two subgroups.
(i). Impedance measurement
(ii). Detection
One setback of these methods is that they enter a disturbance to the grid and may
degrade the power quality of the system.
(c). Hybrid methods
Hybrid islanding detection techniques combine the principles of active and passive
techniques.
In a hybrid islanding detection method which uses total harmonic distortion and
continuous feedback and selection is presented.
In a covariance index is used as the passive method, to activate adaptive reactive
power shift action.
25. In this paper a hybrid islanding
detection method which is on the
principles of VU and HF impedance
is presented.
The imbalance of PCC voltage is
measured, if it is above the selected
threshold, a HF voltage is injected
to the system and the impedance of
the DG is estimated at the injected
frequency.
The propose method can detect
islanding in 32(ms) and discriminate
islanding from other system
disturbances.
Fig.4 Islanding test circuit
26. INVERTER MODELING
Inverters are the main interference sources of the micro-grid . In this paper, two
control strategies are used to control the inverters installed in the micro-grid.
(1). PQ inverter control.
(2). Voltage source inverter (VSI) control.
Fig .5 Basic structure of the PQ inverter control scheme
(1). PQ inverter control
Fig.5 Pref in Fig. 2 represents the active power
which is produced by the micro-source, which is
connected to the Micro-grid by that inverter.
Qref represents the amount of reactive power
injected into or absorbed from the Micro-grid at the
inverter’s bus.
In this model, all PQ inverters operate at unity
power factor ,which means there is no reactive power
conversion between the PQ inverter and the Micro-
grid system.
In PQ inverters were worked at unity power factor
to reduce the ratings of those inverters and the cost.
27. Fig. 6 Voltage source inverter control model.
This kind of inverter is used to feed the Micro-
grid with predefined values of voltage and
frequency subsequent to islanding occurrence.
VSI in this paper is used to interface the
storage device (flywheel) to the Micro-grid
and represents the reference bus (slack bus) for
each Micro-grid during islanding mode.
The VSI emulates the behavior of a
synchronous machine in conventional power
systems.
The VSI is controlled through droops with the
magnitude and frequency of the output voltage,
as described by the following functional
relation:
(2). Voltage source inverter (VSI) control
P and Q are the inverter active and reactive output powers
respectively.
PK and Q K are the F and V droop slopes respectively.
f0 and V0 are the idle values of the frequency and voltages
A 3-ph model of a VSI implementing the droop concepts
described by Equation no. (1)
In this model, the amount of P and Q powers injected into
or absorbed from the Micro-grid will control the V and
frequency of the Micro-grid.
28. RELATIONSHIP OF FREQUENCY
WITH ISLANDING OPERATION
Fig.4 shows the power flow chart of
inverter ,which is based on DG (IBDG)
and connected load in the presence of the
utility.
Under the islanding operation, the power
flow can be described as:
The load is replaced by equivalent RLC
elements and is connected in parallel, PCC
voltage across R and parallel LC are the
same. The load power can be calculated as
From Eqs.(2) and (3), we can get
If IBDG output power Pinv +jQinv is equal or
approximate to the rated load power Load
Load Pload +jQload, the PCC voltage frequency
will under the threshold at the moment, at the
instant the utility is disconnected, the
islanding detection fails.
29. SIMULATION
In this part, simulation results are shown to verify the effectiveness of the proposed islanding
detection algorithm.
The difference between inverter output capacity and rated load capacity is described as:
In this case, the islanding frequency will go beyond the allowable range (49.5 Hz—50.5 Hz)
immediately, and the islanding can be confirmed
The simulation parameters of the system are shown in Tab.I.
PARAMETERS VALUE
Voltage ; Frequency 220V,50Hz
Pload0 5kW,9.68Ω
QL 10KVar, 15.4mH
QC 5KVar, 328.8µH
fmax=wmax/ 2pi ; fmin =wmin/ 2pi 50.3Hz;49.7Hz
30. Fig.8 Simulation result of
Case
(the islanding frequency
exceeds the lower frequency
limit for 3 times within 0.1
s. )
Fig.7. ∆P= -1%Pload0 and the
utility is disconnected at t=0.1s
Fig.9 ∆P= 1%Pload0 , the
islanding frequency should
also shift continuously
when the proposed
algorithm is applied.
31. CONCLUSION
In this paper a hybrid islanding detection method using VU and HF impedance is presented.
The voltage unbalance is measured at PCC and if it overreaches the threshold settings, the
situation is suspicious of islanding.
Therefore, a HF voltage is injected in the DG control loop and the PCC voltages and current
are measured to estimate impedance at the injected frequency.
This hybrid method merges the advantages of active and passive methods.
Furthermore, the method does not lead to system instability since the active method does not
change any parameters of the system.
The test system is simulated in PSCAD/EMTDC to investigate the credibility of the method.
The detection method can detect islanding in 32ms (3 cycles) which is supported by standard.
In conclusion , compared to other existing algorithms, the non-detection region of this
algorithm is very small.
at the same time, it also provides an excellent detection speed of the island. The effectiveness
of the algorithm is proved by the simulation results.
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