Compensation of Unbalanced Sags/Swells by Single Phase Dynamic Voltage Restorer

Authors: S.Manmadha Rao, S.V.R.Lakshmi Kumari,  B.Srinivasa Rao


Abstract

Power quality is the most important aspect in the present power system environment. Among all the power quality problems most frequently occurring disturbances, affecting the quality of power are voltage sags and swells. Custom power device, Dynamic Voltage Restorer (DVR) connected in series with a goal to protect the loads from source side voltage disturbances. In this paper single phase DVR is adopted for each phase instead of using three  phase DVR to compensate unbalanced sags/swells. Programmable voltage source is used to create sags/swells with required magnitude and time period. In this paper voltage type Impedance Source Inverter (ISI) is employed to compensate deep voltage sags/swells. DVR’s employed as series compensators in IPFC scheme to compensate voltage disturbances in individual feeders. Comparative study between PI and Fuzzy controllers is done. The project is carried out in Matlab/Simulink software.

 

Index Terms

Dynamic voltage restorer (DVR), Impedance source inverter (ISI), Interline power flow controller (IPFC)

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Compensation of Unbalanced Sags/Swells by Single Phase Dynamic Voltage Restorer

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Optimal Sizing and Placement of DG in a Radial Distribution Network using Sensitivity based Methods

Authors: Nitin Singh, Smarajit Ghosh, Krishna Murari

Abstract

In recent years, the power industry has experienced significant changes on the power distribution systems primarily due to the implementation of smart-grid technology and the incremental implementation of distributed generation. The distribution power system is generally designed for radial power flow, but with the introduction of DG, power flow becomes bidirectional. Whether the impact of the DG is positive or negative on the system will depend on the location and size of the DG. This paper focuses on testing various indices and using effective techniques for the optimal placement and sizing of the DG unit by minimizing power losses and voltage deviation. A 33-bus radial distribution system has been taken as the test system. The feasibility of the work lies on the fast execution of the programs as it would be equipped with the real time operation of the distribution system and it is seen that execution of the DG placement is quite fast and feasible with the optimization techniques used in this work.

Index Terms

Distribution Network, Distributed Generation, Load flow, Loss Sensitivity Analysis, Voltage Sensitivity Analysis

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Optimal Sizing and Placement of DG in a Radial Distribution Network using Sensitivity based Methods

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Performance and Analysis of Direct Torque Control Induction Motor FED PWM Inverter Drives

Authors: Khadim Moin Siddiqui, Kuldeep Sahay, V.K.Giri


Abstract

AC asynchronous electrical motors especially squirrel cage induction motor presents the greater advantages on cost and energy efficiency as compared with other industrial solutions for varying speed applications. The force-commutated power electronics switches (GTOs, MOSFETs, and IGBTs etc) based inverters are widely employed these days in the conversion of constant speed into variable speed induction motors. Due to the invention of these advanced power electronics switches (GTOs, MOSFETs, IGBTs etc) with improved characteristics, the PWM inverter fed induction motors are widely replacing DC motors and thyrister bridges day by day in the industries. The torque control or field control method may be used with PWM inverter fed induction motors jointly and can achieve the same flexibility in speed and torque control as with DC motors. In this present paper, an IGBT inverter fed squirrel cage induction motor with torque control technique is developed and simulated in the recent MATLAB/Simulink environment and observed the transient characteristics of the used motor. Many motor parameters have been used for induction motor analysis purpose. Further, V/f control and Total Harmonics Distortion (THD) analysis has also been carried out. Though, the stator current parameter of the motor has been widely used from last three decades with Motor Current Signature Analysis (MCSA) technique. Therefore, in the THD analysis, only stator current motor parameter has been analysed.

Index Terms

Squirrel cage induction motor (SCIM), Induction Motor (IM), Pulse width modulation (PWM), Insulated Gate Bipolar Transistor (IGBT), Time Domain Analysis, Direct Torque Control (DTC), V/f Control, MATLAB/Simulink

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Performance and Analysis of Direct Torque Control Induction Motor FED PWM Inverter Drives

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An Effective Technique for Load-Flow Solution of Radial Distribution Networks

Authors: Krishna Murari ,Smarajit Ghosh, Nitin Singh


Abstract

A new method has been developed for load-flow solution of radial distribution systems using matrix method.  The motive of this paper is to propose a technique to identify the nodes beyond each branch with less computational time. The formulated equations have been solved using matrix method. In order to find branch current, node voltage and power loss in the radial distribution network matrix method has been used. Efficacy of this method has been implemented on 33- bus radial distribution systems with constant power (CP), constant current (CC), constant impedance (CZ)  composite and exponential load modelling. The suggested method converges well for constant power, constant current, constant impedance, composite and exponential load modeling. The advantages of proposed method have compared with several existing methods in terms of relative value CPU time and memory size. The proposed method requires much less time to converge and also require less memory size when compared with the several existing methods.

Index Terms

Constant Power Load, Distribution system, Load flow, Load Flow Equations, Radial Distribution systems

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An Effective Technique for Load-Flow Solution of Radial Distribution Networks

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Firefly Algorithm based Optimal Power Flow with Static VAR Compensator for Improvement of Power System Security under Network Contingency

Authors: B.Venkateswara Rao and  G.V.Nagesh Kumar

 

Abstract

At present owing to the increase in power demand   power system have become more complex and heavily loaded, and are subjected to unstable or insecure operations. In order to provide a secure operation of the power system, it is needed to enhance the level of a security margin to the power system. In this paper Firefly algorithm based Optimal Power Flow used to select the optimal sizing of SVC which minimizes the total real power generation cost is proposed. New indices like Line security index and voltage security index are defined for measuring Power system security. This paper was also deals with the impact of SVC under network contingency with Firefly Algorithm based Optimal Power Flow. The results were presented for 5 bus system and modified IEEE 30 bus system without and with SVC in normal operating condition as well as network contingency by using Firefly Algorithm based Optimal Power Flow. The results obtained with Firefly optimization technique was compared with Genetic Algorithm (GA).

 

Index Terms

Flexible AC Transmission System, Firefly Algorithm, Optimal Power Flow, Static VAR Compensator

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Firefly Algorithm based Optimal Power Flow with Static VAR Compensator for Improvement of Power System Security under Network Contingency

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Implementation of SPWM Technique in D-STATCOM for Voltage Sag and Swell

Authors: David Vorganti and Cholleti Sriram

Abstract

This paper presents the implementation of Sinusoidal Pulse width modulation (SPWM) technique to control Voltage Source Controller (VSC) in Distribution STATCOM (D­STATCOM) to mitigate power quality problems, voltage sag and swell. Power quality determines the fitness of electrical power to consumer devices. Synchronization of the voltage frequency and phase allows electrical systems to function in their intended manner without significant loss of performance or life. The major problems in distribution system are the voltage sag and swell. To solve this problem, modern power electronic devices are used. One of those devices is the Distribution STATCOM (D-STATCOM), which is the most efficient and effective FACTS based modern power device used in power distribution networks. D-STATCOM injects a current in to the system to correct the voltage sag and swell. The control of the Voltage Source Converter (VSC) is done with the help of SPWM. The proposed and implementation of SPWM in VSC of D-STATCOM is designed and simulated using MATLAB/SIMULINK software.

Index Terms

Dynamic Analysis, DSP-Based Control, Hybrid Stepping Motor

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Implementation of SPWM Technique in D-STATCOM for Voltage Sag and Swell

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Random Search Technique Applied to Quasi-Optimal Design of a Distribution Transformer

Authors: Raju Basak, Arabinda Das and Amarnath Sanyal

Abstract

Distribution transformers are used to cater power to the consumers Power system components should be designed cost-optimally for better economy. Various techniques are used to reach the optimality condition. The specifications have to be fulfilled, generally in presence of given constraints. The objective functions are framed according to the need of the utilities and the consumers. Constraints are imposed as per directives of electricity regulatory authorities. In this paper a new approach has been made to reach the optimal design for a 3-phase distribution transformer- the random search technique. Random numbers have been generated by randomizing the timer and the values of the key variables have been randomly chosen in the variable space defined by the bounds and widened to cover the global optima. The minimal cost and the corresponding values of the key variables have been trapped by opening a counter and then the design has been made using these values. In this approach, the total no of iterations is much less as well as the level of complexity. The design is very near to optimal or quasi-optimal- it has been established by comparing the results with those obtained by exhaustive search.

 

Index Terms

Distribution transformer, optimal design, design variables, specifications and constraints, random search technique

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Random Search Technique Applied to Quasi-Optimal Design of a Distribution Transformer

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Single objective optimization using PSO with Interline Power Flow Controller

Authors:  Praveen.J and B.Srinivasa Rao


Abstract

Optimal Power Flow (OPF) problem was solving from the decades with different objectives as the economy was growing. In this paper cost of generation, transmission losses and L-index are taken as three different objectives for optimal operation of power system with and without FACTS device. One of the VSC based multi type FACTS device namely an Interline Power Flow Controller (IPFC) is placed into power system network. The optimization problem has been solved by using Particle Swarm Optimization (PSO) with power injection model of the FACTS device. The proposed methodology is tested on standard IEEE 30-bus test system and the results are compared for single objective optimization with and without FACTS device.

Index Terms

IPFC, PSO, OPF

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Single objective optimization using PSO with Interline Power Flow Controller

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Comparison of Fuzzy PID Controller with Conventional PID Controller in Controlling the Speed of a Brushless DC Motor

Authors: S. Sunisith   Lizi Joseph and   M. Saritha


Abstract

Brush less DC motors are widely used for many industrial applications because of their high efficiency, high torque and compact size. The proposed speed controlling technique used to control the speed of a brushless DC motor is based on proportional integral derivative controller and Fuzzy proportional integral derivative controller. This paper describes the overview of performance of conventional proportional integral derivative controller and Fuzzy proportional integral derivative controller. It is difficult to tune the parameters and get satisfied control characteristics by using normal conventional proportional integral derivative controller. As the Fuzzy has the ability to satisfy control characteristics and it is easy for computing in order to control the Brushless DC motor. Fuzzy proportional integral derivative controller is designed to control the speed of Brushless DC motor. The modeling, control and simulation of the Brush less DC motor have been done using the software package MATLAB to control the speed of Brushless DC motor. The results proved that a Fuzzy proportional integral derivative controller is better than Conventional proportional integral derivative controller.

Index Terms

Fuzzy Proportional Integral Derivative and Brushless DC Motor, Speed Control

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Comparison of Fuzzy PID Controller with Conventional PID Controller in Controlling the Speed of a Brushless DC Motor

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Simulation of Distributed Interline Power Flow Controller (DIPFC) for Power Quality Improvement in Distribution System

Authors: Kotipalli Vineela Chandrika and Palakaluri Venkatesh


Abstract

Flexible AC Transmission System (FACTS) became very popular for control of power flow in transmission lines. The Load changes the voltage Variation in transmission lines must be limited, otherwise the consumer’s equipments are damaged at distributed side. For reducing this voltage variation a FACTS device called Distributed Power Flow Controller (DPFC) and Distributed Interline Power Flow Controller (DIPFC) is used.  The DPFC is derived from the unified power-flow controller (UPFC). The DPFC (Distribute Power-Flow Controller) modified from UPFC for increasing system reliability and reducing costs.  The DPFC can be considered as UPFC with an eliminated common DC link, to enable the independent operation of the shunt and the series converters which enhances the effective placement of the series and shunt converters. The active power exchange between the two converters, which is through the common dc link in the UPFC, is now through the transmission lines at the third-harmonic frequency in the DPFC and DIPFC. In DPFC three-phase series converter is divided to several single-phase series distributed converters through the transmission line and in DIPFC three single phase series converters are placed in between the two transmission lines. This paper consists of both active and reactive variations, using MATLAB/SIMULINK is simulated and its effects on the transmission lines observed. The simulated results are analyzed and validated with the real time results for the system considered.

Index Terms

FACTS, DPFC, DIPFC, UPFC, Power Quality

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Simulation of Distributed Interline Power Flow Controller (DIPFC) for Power Quality Improvement in Distribution System

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