DSpace Collection:
https://elibrary.tucl.edu.np/handle/123456789/17052
2024-03-19T18:20:33ZTRANSIENT STABILITY ANALYSIS OFAN INTERCONNECTED ELECTRICAL POWER SYSTEM
https://elibrary.tucl.edu.np/handle/123456789/19267
Title: TRANSIENT STABILITY ANALYSIS OFAN INTERCONNECTED ELECTRICAL POWER SYSTEM
Authors: Poudyal, Deepak; Jha, Raushan Kumar
Abstract: Since solar power systems are connected to the grid using technologies other than those used by traditional power systems, the increased penetration of solar energy into the traditional power grid may modify certain of its transitory features. Particularly, the increased use of non-synchronous generators has an impact on the Critical Clearing Time (CCT), which is crucial for protective system performance during turbulent periods. In a typical IEEE 9 bus test system, this work examines the transient stability analysis of a power system and the effects of photovoltaic (PV) penetration on it. The simulation software ETAP is used to prepare the Simulink model for the transient stability of the IEEE 9 bus test system. The study takes into account three-phase faults, and several simulations are used to examine the stability of the rotor angle. Critical clearing time is used to compare the transient stability in various scenarios, such as with and without PV in the system, and is used as an index to examine the transient stability analysis of the IEEE 9 bus test system for base case. It has been discovered that transient stability depends on the fault's duration, position, and power. While it has improved in some places, the integration of PV into the system has decreased the transient stability of the power supply at important spots.
Description: Since solar power systems are connected to the grid using technologies other than those used by traditional power systems, the increased penetration of solar energy into the traditional power grid may modify certain of its transitory features. Particularly, the increased use of non-synchronous generators has an impact on the Critical Clearing Time (CCT),2023-04-01T00:00:00Z“SELECTIVE HARMONIC ELIMINATION”
https://elibrary.tucl.edu.np/handle/123456789/19266
Title: “SELECTIVE HARMONIC ELIMINATION”
Authors: Kunwar, Jibalal; Paudel, Prakash; K.C., Ramesh; Bista, Sanil
Abstract: Selective Harmonic Elimination (SHE) is a widely used technique in power electronic converters to mitigate the detrimental effects of harmonics on system performance. Harmonics, which are undesired sinusoidal components occurring at frequencies that are multiples of the fundamental frequency, can lead to waveform distortion, increased losses, and interference with other electronic devices. The SHE technique selectively eliminates specific harmonics from the output waveform by precisely controlling the switching instants of the converter. This research project focuses on investigating the theory and implementation of Selective Harmonic Elimination for square wave inverters, which commonly produce harmonically rich waveforms due to the abrupt transitions in the output voltage. The primary objective of this study is to design a selective harmonic elimination pulse width modulation (SHE PWM) controller for square wave inverters to reduce the Total Harmonic Distortion (THD) present in the output waveform. The research project aims to develop an effective SHE algorithm capable of selectively eliminating specific harmonics while preserving the desired characteristics of the output waveform.
Description: The project encompasses several stages, including algorithm design, simulation, validation, implementation, and testing. In the algorithm design phase, the fundamental principle of SHE is explored, which involves determining a set of switching angles that result in the elimination of a particular harmonic.2023-04-01T00:00:00Z“DESIGN AND FABRICATION OF SOLID-STATE ON-LOAD TAP CHANGER”
https://elibrary.tucl.edu.np/handle/123456789/19265
Title: “DESIGN AND FABRICATION OF SOLID-STATE ON-LOAD TAP CHANGER”
Authors: Neupane, Kismat; Niraula, Kshitij; Chaudary, Mahesh; Ray, Nikesh
Abstract: In the recent time, the continuous, uninterrupted and fast power supply along with high efficiency is one of the major concerns in the field of power system. It is necessary that our system should react quick to increase and decrease in heavy as well as light load. The on-load tap changers have become one of the important parts of transformer in order to regulate the constant output voltage without disconnecting the load. The purpose of this project is to design the most convenient type of tap-changing system that omits all the disadvantage of the present type of tap changing. It focuses on how current tap changing system is working, what are the problems associated with it and hence how can we replace them by using modern tools, devices, systems and methods. Earlier mechanical type on-load tap changers were in use which had major shortcomings like arcing, slow response time, high maintenance and service costs. And these get even worse in the case distribution transformers which are manually operated that too after disconnection of load and hence do not provide dynamic control over output voltage and require constant human intervention. Due to these flaws of the mechanical type, solid-state (electronic) tap changers were introduced.
Description: This project introduces the most efficient method of tap-changing system by replacing old, bulky, manually operating and late reacting system of tap-changing. The newly introduced system is easy in designing, small in size, arc free, quick responsive, automatic, easy to handle and economical for investing, operating and maintaining. Thus, in this report implementation of such EOLTC is presented with micro- controller-based control strategy providing higher degree of flexibility in modifying the control algorithms.2023-04-01T00:00:00ZENHANCEMENT OF FAULT RIDE THROUGH CAPACITY OF GRID CONNECTED INVERTER
https://elibrary.tucl.edu.np/handle/123456789/19262
Title: ENHANCEMENT OF FAULT RIDE THROUGH CAPACITY OF GRID CONNECTED INVERTER
Authors: Yadav, Barma; Paudel, Bishnu; Pokharel, Kajal; Mahato, Rahul Kumar
Abstract: Under the demands of contemporary grid code (GC), the solar PV system should stay
attached to the grid for a certain time period depending on the voltage sag level under the
fault condition. The voltage of the point of common coupling (PCC) is the same when the
fault appears on the grid side due to compensation of voltage by the grid connected system.
But the output voltage of inverter is very low when fault occurs in the inverter side
resulting in a very high DC connection voltage and very high current through the inverter
for the power balance. This high voltage of the intermediate circuit can damage the DC
link capacitor and high current during the transient fault may damage the inverter.
Moreover, the deflection of the voltage will cause the PV plant to be disconnected from the
network based on the modern GCs. But, due to on-growing demand of consumers, it is
required to connect the PV system to grid even during faulty condition.
This study proposes a DC Braking chopper approach for the two-stage grid-integrated
solar PV system to enhance fault ride through (FRT) capability. The proposed DC Braking
control approach consists of a resistor in series with IGBT which absorbs the excess
energy in the DC link capacitor during the fault, which will regulate the DC-link
overvoltage where required PWM signal for IGBT used in DC braking chopper is
generated by the principle of power balance between DC side and AC side.
Description: This study proposes a DC Braking chopper approach for the two-stage grid-integrated
solar PV system to enhance fault ride through (FRT) capability. The proposed DC Braking
control approach consists of a resistor in series with IGBT which absorbs the excess
energy in the DC link capacitor during the fault, which will regulate the DC-link
overvoltage where required PWM signal for IGBT used in DC braking chopper is
generated by the principle of power balance between DC side and AC side.2023-04-01T00:00:00Z