8 research outputs found
Impacts on Power Factor of AC Voltage Controllers Under Non-Sinusoidal Conditions
ABSTRACT AC-AC conversion is obtained with the help of Cyclo-converters, DC Link converters and AC Voltage Controllers. AC voltage controllers are also referred to as voltage regulators. Main issue concerned to these converters is that they generate harmonics due to periodic variable structure system. The generated harmonics create disturbances and degrade the performance of converter. The power factor of supply side is affected due to these harmonics. This paper focuses on source side power factor of ac voltage controllers under nonsinusoidal conditions. In order to observe the power factor, measurement tool of power factor and simulation model of ac voltage controller is also developed in MATLAB software
Decentralized Hierarchical Controller Design for Selective Damping of Inter Area Oscillations Using PMU Signals
This paper deals with the decentralized hierarchical PSS (Power System Stabilizer)
controller design to achieve a better damping of specific inter-area oscillations. The
two-level decentralized hierarchical structure consists of two PSS controllers. The
first level controller is a local PSS controller for each generator to damp local mode in
the area where controller is located. This controller uses only local signals as input
signals. The local signal comes from the generator at which the controller is located.
The secondary level controller is a multivariable decentralized global PSS controller
to damp inter-area modes. This controller uses selected suitable wide area PMU (Phasor
Measurement Units) signals as inputs. The PMU or global signals are taken from
network locations where the oscillations are well observable. The global controller
uses only those global input signals in which the assigned single inter-area mode is
most observable and is located at a generator that is most effective in controlling the
assigned mode. The global controller works mainly in a frequency band given by the
natural frequency of the assigned mode. The effectiveness of the resulting hierarchical
controller is demonstrated through simulation studies conducted on a test power system
Harmonic Analysis of AC-DC Topologies and their Impacts on Power Systems
Power Electronic Converters are commonly used in different applications because of
high efficiency and low cost. Due to latest advancement in semiconductor devices it is
difficult to draw the boundaries for applications of power electronic topologies. These
topologies are variable structure systems and generate harmonics during the operation
which will affect the power quality when are connected to system network.
Rectifier is a big family of converters and used when ac-dc conversion is needed. These
converters are widely used in distribution system. Therefore, it is necessary to predict
the harmonic levels of these converters and also observe their impacts on system
network.
Pakistan now days facing serious energy crises specially, in power sector due to
increase in load demand. To bridge the gap between load demand and generation of
electricity, various steps are taken by power companies and government. The steps
include the up gradation of existing power plants, generation of power from rental
power plants, installation of renewable power sources, taking different steps of demand
side management etc. But efforts of power companies on power quality is still lacking.
This research work focuses on power quality of the system network. In this work,
harmonics of single phase and three phase full bridge diode rectifiers are analyzed by
using the fast fourier transform method of MATLAB. The effects of harmonics on the
system network are also discussed
Impacts on Power Factor of AC Voltage Controllers Under Non-Sinusoidal Conditions
AC-AC conversion is obtained with the help of Cyclo-converters, DC Link converters and AC Voltage
Controllers. AC voltage controllers are also referred to as voltage regulators. Main issue concerned to
these converters is that they generate harmonics due to periodic variable structure system. The generated
harmonics create disturbances and degrade the performance of converter. The power factor of supply
side is affected due to these harmonics.
This paper focuses on source side power factor of ac voltage controllers under nonsinusoidal conditions.
In order to observe the power factor, measurement tool of power factor and simulation model of ac voltage
controller is also developed in MATLAB software
Performance Analysis of Phase Controlled Unidirectional and Bidirectional AC Voltage Controllers
AC voltage controllers are used to vary the output ac voltage from a fixed ac input
source. They are also commonly called ac voltage regulators or ac choppers. The
output voltage is either controlled by PAC (Phase Angle Control) method or on-off
control method. Due to various advantages of ac voltage controllers, such as high
efficiency, simplicity, low cost and ability to control large amount of power they efficiently
control the speed of ac motors, light dimming and industrial heating, etc.
These converters are variable structure systems and generate harmonics during the
operation which will affect the power quality when connected to system network. During
the last couple of years, a number of new semiconductor devices and various power
electronic converters has been introduced. Accordingly the subject of harmonics and
its problems are of great concern to power industry and customers. In this research
work, initially the simulation models of single phase unidirectional and bidirectional
ac voltage controllers were developed by using MATLAB software. The harmonics of
these models are investigated by simulation. In the end, the harmonics were also
analyzed experimentally. The simulated as well as experimental results are presented
Simulation-Based Comparison of PID with Sliding Mode Controller for Matrix-Converter-Based Dynamic Voltage Restorer under Variation of System Parameters to Alleviate the Voltage Sag in Distribution System
A constant power supply is a basic need for each consumer due to the increase in sensitive equipment day by day. As per IEEE standards, a 10% reduction in voltage from the supply voltage is not acceptable and may cause the failure of equipment. Previously, different techniques have been used to alleviate the voltage sag, such as STATCOM, DSTATCOM, SVC, and shunt capacitors, but these devices are connected in parallel, which compensates for the low value of voltage sag, and they have high maintenance costs involved. Compensation for the low and high values of voltage sag is possible through a series-connected device such as a dynamic voltage restorer. In this paper, a matrix converter is presented for DVR to convert AC to AC voltage directly and free from batteries, capacitors, and multiple conversions as needed in a voltage source inverter, resulting in a reduced cost of DVR topology. The DVR is meaningless in the absence of a controller, so it is necessary to select a suitable controller for the satisfactory operation of the DVR under a variation of system parameters. In this paper, the performance of a linear PID controller is analyzed and compared with a nonlinear controller, such as a sliding-mode controller, under variation of power system parameters inorder to select a robust controller that performs satisfactorily for DVR. Earlier trial-and-error methods were used to obtain the parameters of PID gains, but they require a large time to obtain the parameters of the PID gains and there is a chance of inaccuracy. A genetic algorithm was used to obtain the gain parameters, but it has more convergence time and the particle swarm optimization technique has involves less reliability. In this research paper, the sliding surface coefficient parameters such as and Ki for the PI sliding surface of SMC and PID gains are taken through an ant colony algorithm to obtain the robustness of the controllers. The purpose of this paper is to introduce the best DVR topology with reduced cost. MATLAB simulation software was utilized to analyze the performance of the DVR with PID and SMC controllers under different fault conditions and also the THD% of proposed controllers was analyzed through FFT
Simulation-Based Comparison of PID with Sliding Mode Controller for Matrix-Converter-Based Dynamic Voltage Restorer under Variation of System Parameters to Alleviate the Voltage Sag in Distribution System
A constant power supply is a basic need for each consumer due to the increase in sensitive equipment day by day. As per IEEE standards, a 10% reduction in voltage from the supply voltage is not acceptable and may cause the failure of equipment. Previously, different techniques have been used to alleviate the voltage sag, such as STATCOM, DSTATCOM, SVC, and shunt capacitors, but these devices are connected in parallel, which compensates for the low value of voltage sag, and they have high maintenance costs involved. Compensation for the low and high values of voltage sag is possible through a series-connected device such as a dynamic voltage restorer. In this paper, a matrix converter is presented for DVR to convert AC to AC voltage directly and free from batteries, capacitors, and multiple conversions as needed in a voltage source inverter, resulting in a reduced cost of DVR topology. The DVR is meaningless in the absence of a controller, so it is necessary to select a suitable controller for the satisfactory operation of the DVR under a variation of system parameters. In this paper, the performance of a linear PID controller is analyzed and compared with a nonlinear controller, such as a sliding-mode controller, under variation of power system parameters inorder to select a robust controller that performs satisfactorily for DVR. Earlier trial-and-error methods were used to obtain the parameters of PID gains, but they require a large time to obtain the parameters of the PID gains and there is a chance of inaccuracy. A genetic algorithm was used to obtain the gain parameters, but it has more convergence time and the particle swarm optimization technique has involves less reliability. In this research paper, the sliding surface coefficient parameters such as and Ki for the PI sliding surface of SMC and PID gains are taken through an ant colony algorithm to obtain the robustness of the controllers. The purpose of this paper is to introduce the best DVR topology with reduced cost. MATLAB simulation software was utilized to analyze the performance of the DVR with PID and SMC controllers under different fault conditions and also the THD% of proposed controllers was analyzed through FFT