57 research outputs found
Development of automatic power factor correction system by using PIC microcontroller through simulation study
No full textThis thesis presents the design and analysis of an automatic power factor correction
system using PIC microcontroller for single phase low voltage distribution system
(230V/50Hz). Power factor plays a great role in an electrical system. A low power
factor will draw more current in the system and this will lead to high electricity bills and
higher power loses. Conventional way to improve power factor is by installing a static
capacitor bank which is connected permanently to the electrical system through fused
switches. However, this method is not effective as the load is usually fluctuating
according to demand. Hence, the operation and power factor correction is not optimized
as the capacitive compensation does not change according to load variations. Therefore,
a system that will adjust the power factor automatically according to load fluctuations is
needed. So, in this project an automatic power factor system will be designed and
developed in order to solve this problem. The designed system is basically used a PIC
18F452 microcontroller to calculate and control power factor in an electrical system by
automatically connect or disconnect capacitor banks according to load changes. The designed system has been tested in Proteus development software
Application of D-STATCOM to mitigate high inrush current during start-up of three-phase induction motor
No full textThis thesis presents the application of Distribution Static Compensator (D-STATCOM) to mitigate inrush current during start up three phase induction motor. Three phase induction motor draws high current during starting period and will from 6 to 7 times of
the rated current of the motor. The effect of high starting current will cause severe
damage to motor itself, especially overheating and making motor life expectancy short.
In addition, the high starting current will cause the voltage of the power supply rapid
drop and affect other devices’ running in the same power line. The purpose of this thesis
is to demonstrate that a D-STATCOM is capable to mitigate inrush starting current
during start up induction motor. The controller circuit of D-STATCOM has been
simulated by using Power System Computer Aided Design (PSCAD/EMTDC)
software. The research methodology of this project is to design D-STATCOM circuit
which consists of Voltage Source Converter as a main circuit. The function of this
circuit is to convert AC to DC and then invert DC to AC before transmit to the threephase
power line. The circuit’s has a capability to absorb and inject the reactive and
active of the power system which is to control the magnitude of the VSC output voltage.
To compare the capability of the D-STATCOM, a Soft starter is developed. The Soft
starter circuit is controlled by six thyristors. There were three methods which can be
used such as starting the induction motor with direct start-up, starting the induction
motor by connecting with the D-STACOM and starting the induction motor with Soft
starter. The starting currents of these three methods were observed up to 30
milliseconds and compared. The analysis result shows that the D-STATCOM had
mitigated inrush current during start-up induction motor up to 74% higher compared to
direct start-up and 164 Ampere is the highest inrush current recorded while direct startup
was 637 Ampere recorded. The D-STATCOM was compared with Soft starter to
determine the ability of reducing inrush current during start-up induction motor. The
result shows that the D-STATCOM had mitigated of 54.3% higher inrush current
compared with Soft starter. Hence, the conclusion of this research is the D-STATCOM
has a higher capability to reduce inrush current during start up the induction motor
compared with Soft starter
Determination of optimized soft starter firing angle to mitigate high inrush current during motor starting using PSCAD
No full textMaster of Science in Electrical Power EngineeringStarting of an induction motor is a process that creates many challenging problems for
the motor and operations of the power system. The induction motor can be damaged,
characteristic can be changed and performance of the motor can be worsen. An
induction motor draws a high starting current and develops a high torque during the
start-up. Inrush current often causes problem such as voltage dips and sags that occur in
electrical power system associated with motor. The different motors starters available in
Malaysia market are being discussed and analyzed. It includes both conventional
electromechanical starters and power electronic drives. A comparison between the
starters found that soft starter is the most convincing because the configuration just
involves some power conductor device that control the current flow from power source
to the motor. The switch is in the form of thyristor and being connected back-to-back.
The current output can be controlled by varying the firing angle. This changing of firing
angle is managed by a firing angle control circuit. PSCAD/EMTDC software is used for
model implementation and in carrying out extensive simulation studies. Firstly, the
power source was directly connected to the induction motor and the circuit is simulated
to analyze the inrush current. The analysis of the starter is repeated by using star delta
starter and soft starter. For soft starter, the thyristor acts as a gate to control the voltage
applied to the motor. The firing angle was varied until the high current was mitigated.
This research was finally concluded that soft starter circuit is designed to be used to
mitigate inrush current
Comparative study of motor high inrush current mitigation by improvisation of soft starter firing angle using PSCAD
No full textMaster of Science in Electrical Power EngineeringInrush current can be determined as current drawn by an induction motor during start-up period. This starting current will shoot up about 5 to 7 times of rated current. Usually, it was occurred at the starting period of induction motor and effect the lifetime of
motor.To overcome this, several techniques can be implemented to reduce the high starting current. One of the technique isusing the soft starter which is the most convincing because of its simplicity in configuration, easy to control and low cost. The
configuration involves power semiconductor devicewhich is thyristor that acts as a switch to control the current flow from power source to the motor. The current output can be controlled by varying the firing angle. Thechanging of firing angle is managed
by a firing angle control circuit. The whole research was conducted through PSCAD/EMTDC software. In simulation, the power source, AC voltage was connected directly to the induction motor called direct on-line (DOL) and the DOL circuit was
simulated to analyse the inrush current. From the simulation of DOL, the soft starter was added to the original circuit. The firing angle for soft starter was changed to several angles and what can be concluded that the high current succeed to mitigate with the
altering firing angles.Simulation DOL and soft starter method were carried out with 3 different rated power which were 116kVA, 232kVA and 435kVA. Higher rated power resulting higher inrush current. As for the overall result, the inrush current was
mitigated for all 3 rated power by using soft starter with the best adjusted firing angle
Energy encryption for medium field of wireless power transfer system
No full textMaster of Science in Electrical System EngineeringNowadays, the wireless power transfer (WPT) on mobile charging application of power transfer is the process of transferring power using WPT technology are progressing rapidly. The launching of more mobile embedded with WPT system make it as currently most demanding technology. In WPT, the main issue that being investigated are focused on power transfer efficiency (PTE), effective distance and the size of transmitter and receiver itself. Apart from that, the security of the power transfer is very important from transmitter to selected receiver must be completely secure. The failure to secure WPT
system has affected the process to transfer power from transmitter to correct receiver.
This thesis presents method which manipulates chaos theory to ensure the security of
energy is encrypted to transfer and recovered as security at the correct receiver efficiently
with higher security. In chaos theory technique, there are chaotic behaviour element
which being embedded using the logistic map and Lyapunov exponent for additional
security with matching the switching frequency of the transmitter and receiver. Chaotic
behaviour is triggered on each characteristic which are Lyapunov exponent, logistic map
and switching frequency. For this research, the application of WPT is focused on mobile
charging application and its security efficiency is tested through chaos theory. Thus,
detailed study is carried out by varying the power operation, distance of effective PTE
and the capacitor combination. The system is simulated using MATLAB programming
by creating and simulating WPT environment. The simulation took all the characteristic
and specification of mobile charging application which is resides within medium field
range. The operating frequency is around 100 kHz, operating power of 10 W and distance
are adjusted from 3 cm to 5 cm. The simulation is done by sample taking into account
that characteristic of chaos theory which are logistic map, Lyapunov exponent, matching
switching frequency and matching security key. Lyapunov exponent which triggered the
matching frequency process must be greater than 3.50. As for this research, the Lyapunov
exponent value is chosen by random and it is greater than 3.50. The sampling result shows
that, the power is securely transferred by the following data: delivered power of 10 W,
matching frequency of 102 kHz (±2% at 100 kHz) and matching security key for
transmitter and receiver of 1.02 and 0.86 respectively. As the conclusion, results show
that chaos theory technique is effectively employed for security of energy encryption
process. It also managed to transfer energy from a transmitter to the intended receiver.
This is proven by the utilization of chaos theory technique of transmitter encrypted power
at distance of 4 cm between the transmitter and receiver
Effect of THD towards temperature properties of power conductor under harmonic influence
Get PDFPower delivery system is having a great effect
upon the existence of harmonic in power system. The
ability of harmonic to influence some variable on power
cable such as temperature and current has been a main
issue regarding the safety of power cable as many
electronic types of equipment are being introduced today,
compared to .the past. They are nonlinear loads which tend
to inject harmonic into whenever system they are in.
Harmonic current tends to raise current magnitude into
certain level and that adds extra burden of heat to the
power cable. This paper investigated power loss
component in a power cable, where an experiment
designed to enable the component of harmonic being
injected at will. The effect of THD towards temperature of
the cable is analyzed and documented in form of graphical
evidences. The pattern of current and temperature raise
also taken into account and analyzed with great interes
A New Design Of Three Phase Transformer Under Nonlinear Load Condition
Get PDFUsage of nonlinear loads such as electronic device causes current at power distribution system to be distorted and contains harmonic. Effect of current harmonic is overheating of transformer at power distribution system. Overheating is caused by the increase of copper power loss at winding wire and core power loss (hysteresis and eddy current). As result insulation is degraded and risk of permanent malfunction at transformer (burn). Existing solutions regarding this problem is by reducing and increasing transformer capacity and the reduce of transformer loading. This gives bigger area to sustain effect of current harmonic. This thesis proposes a new design three phase transformer without changing of capacity. This can be achieved by resizing of winding wire and core. This transformer is specially design for nonlinear loading with current harmonic content (THDi) of 40%. Resizing method is performed at transformer material of winding wire and magnetic core in order to sustain the additional loss caused by current harmonic. It also reduces copper loss at winding wire and hysteresis loss at transformer core. Resizing technique is based on the determination of sizing factor with the function of THDi that is proportion to rated transformer operating temperature. It is the ratio between transformer operating temperatures under nonlinear loading. Experimental result on a three phase 2 kVA, 415V, 50Hz transformer yields sizing factor of 0.012 and 0.075 for winding wire and core respectively By utilizing the determined sizing factor, a new transformer is designed with winding wire AWG 19 and core with dimension 1358cm2. It is able to sustain additional transformer power loss caused by current harmonic as much 40% THDi at rated operating temperature 55°C. This design method can be improved by considering selection of material with higher permeability to the extent design dimension of transformer is made smaller (more economical)
Determining Correction Factor Of Power Cable Sizing Under Nonlinear Load Condition
Get PDFPeralatan elektrik yang berasaskan peranti elektronik telah mengundang masalah kualiti kuasa yang serius iaitu harmonik. Peralatan berkenaan dikenali juga sebagai beban tidak linear mampu mengenakan herotan pada parameter voltan dan arus.
The invention of electronic equipment has lead to a serious power quality problem in harmonics. The equipments, also known as the nonlinear loads have the ability to distort
parameters such as voltage and current
Impact of Nonlinear and Unbalanced Loads on Neutral Conductors in Three-Phase Systems: Modelling and Simulation Analysis
No full textThe rise of nonlinear and unbalanced loads in modern electrical systems poses challenges to power quality management. These loads, prevalent in electronic devices and industrial equipment, induce harmonic distortions and unbalance, adversely affecting the neutral conductor in three-phase systems. This study investigates these effects through modeling and simulation using MATLAB/Simulink and symmetrical components theory for detailed power quality analysis. The research focuses on three scenarios: nonlinear loads, unbalanced loads, and combined nonlinear-unbalanced loads. Simulation results show that nonlinear loads significantly increase harmonic content, while unbalanced loads lead to notable power quality deviations. When combined, these conditions exacerbate harmonic distortions and unbalance, resulting in higher neutral current magnitudes. Key findings highlight the severe impact of combined load conditions on the neutral conductor, emphasizing the need for accurate modeling and analysis. This research provides valuable insights and practical recommendations for addressing the challenges of nonlinear and unbalanced loads, contributing to improved power system design and management
- …
