Mitigation of Unbalanced Voltage Sag/Swells Using Dynamic Voltage Restorer Based on Super Capacitor

Vol. 2  Issue 4
Year: 2015
Issue:Nov-Jan
Title:Mitigation of Unbalanced Voltage Sag/Swells Using Dynamic Voltage Restorer Based on Super Capacitor
Author Name:K. Venkateswarlu et.al 
Synopsis:

This paper presents the design and operation of three phase four wire Dynamic Voltage Restorer (DVR) based on supercapcitor as energy storage to compensate voltage sag/swell in electrical distribution system. The proposed system comprises of power circuit of the DVR, Voltage source inverter and supercapcitor as an energy storage device. It involves the control strategy for the operation of DVR during disturbances in the supply voltage. Control scheme is designed using SRF theory coupled to Proportional Integral (PI) controller technique which is applied to the DVR. The operation of the DVR depends on the control circuit topologies. The main aims of this paper is to design, operate DVR power circuit using SRF and PI techniques to mitigate unbalanced voltage sag/swells in three phase four wire Electrical distribution system. This paper is competent to mitigate voltage disturbances even at low voltage distribution system. The execution of supercapcitor as energy storage is to render real power to the inverter throughout malfunctioning in the supply voltage. The proposed controller was then simulated and outputs were carried out using MATLAB/SIMULINK software.

Optimal Multi-Objective Hybrid Measurement Placement Using NSGA-II

Vol. 2  Issue 3
Year: 2014
Issue:Aug-Oct
Title:Optimal Multi-Objective Hybrid Measurement Placement Using NSGA-II
Author Name:Basetti Vedik and Ashwani Kumar Chandel
Synopsis:

In this paper, non-dominated sorting genetic algorithm-II(NSGA-II) is proposed for optimal placement of hybrid, i.e. PMUs and conventional meters. The hybrid measurement placement problem has been solved by simultaneously optimizing the two conflicting objectives, viz, Maximizing the measurement redundancy and the other, minimizing the installation cost ensuring full network observability. The Pareto optimal solutions are obtained using the non-dominated sorting and crowding distance criterion. Subsequently, a decision making procedure based on VIKOR method is employed to determine the best conciliation solution from the set of Pareto-optimal front. The effectiveness and flexibility of the proposed algorithm has been tested on IEEE 14-bus, IEEE-30 bus, and IEEE 57-bus systems respectively

Observability Analysis, State Estimation & Bad Data Detection For Power System Using Measured Data

Vol. 2  Issue 3
Year: 2014
Issue:Aug-Oct
Title:Observability Analysis, State Estimation & Bad Data Detection For Power System Using Measured Data
Author Name:Manjula S. Sureban and S.G. Ankaliki
Synopsis:

This paper presents a simple algorithm for the Static State Estimation of a Power System. The proposed algorithm makes use of the Weighted Least Square Estimation techniques to estimate the Static State of Power System and hence to analyse the observability of the power system network. Concept of Chi-square test is used to detect the presence of bad measurements in the available data. Developed algorithm is demonstrated for sample 2 bus system.

Approximate System Reliability Analysis of Power System networks using Cutsets

Vol. 2  Issue 3
Year: 2014
Issue:Aug-Oct
Title:Approximate System Reliability Analysis of Power System networks using Cutsets
Author Name:D. Ravi Kumar and V. Sankar 
Synopsis:

A system is a collection of components arranged to a specific design in order to achieve desired functions with acceptable performance and reliability. Reliability engineers often need to work with systems having elements connected in series and parallel, and to calculate their reliability. To this end, when a system consist of combination of series and parallel segments, engineers often apply very convoluted block reliability formulae and use software calculation packages. As the underlying statistical theory behind the formulae is not always well understood, errors or misapplications may occur. In this paper, exponentially distributed failure rate of the components will be considered for unit or component redundancies and evaluation of basic probability indices for various system configurations like series parallel, series-parallel, parallel-series configurations and complex systems have been dealt with deriving generalized expressions for ‘n’ component repairable systems. A computer program has been developed to apply generalized expressions for various systems. Application of the derived formulae is used to obtain basic probability indices of load point and for the Power System network.

Multilevel Inverter With Variable Amplitude Multicarrier PWM Techniques

Vol. 2  Issue 3
Year: 2014
Issue:Aug-Oct
Title:Multilevel Inverter With Variable Amplitude Multicarrier PWM Techniques
Author Name:P. Suresh Pandiarajan, S.P. Natarajan and C.R. Balamurugan
Synopsis:

This paper deals with Single Phase Five level Inverter using Multi Carrier Based Pulse Width Modulation Technique. The voltage quality of conventional two level inverter is poor due to the presence of harmonics and hence produces power loss which reduces the efficiency of the system. The multilevel inverter is used to improve the voltage quality by reducing the harmonics. As the number of voltage levels of multilevel inverter is increased, the harmonics are reduced and hence losses are minimized significantly. The simulation of single phase cascaded five level multilevel is done using Multicarrier PWM technique and compared with sine wave. Here the authors compared conventional PD and variable PD and simulated outputs were given.

Role of Power Converters for DFIG based Wind Energy Conversion Systems

Vol. 2  Issue 3
Year: 2014
Issue:Aug-Oct
Title:Role of Power Converters for DFIG based Wind Energy Conversion Systems
Author Name:Venkatasubramanian. R and Raghavendiran. T. A
Synopsis:

This paper explains different converter topologies with different induction generators used for wind energy conversion system. In this focused area of renewable energy resources, wind energy conversion system is more popular than the other conversion systems. Four main types of induction generator used in wind energy conversion system (WECS) are Squirrel Cage Induction Generator (SCIG), Permanent Magnet Synchronous Generator (PMSG), Doubly Fed Induction Generator (DFIG), and Wound Field Synchronous Generator (WFSG). Presently, Doubly-Fed Induction Generator (DFIG) is widely employed in modern wind power industries. The maximum electrical power can be obtained in both wind speeds of above and below synchronous speed using DFIG. Also, it reduces the power rating of the converter. This paper mainly explains the study concepts of Power converter topologies used with Doubly Fed Induction Generator (DFIG) connected wind energy conversion system

Load Frequency Control of Multi Area Inter Connected Power System by Conventional and AI Based Controllers

Vol. 2  Issue 2
Year: 2014
Issue:May-Jul
Title:Load Frequency Control of Multi Area Inter Connected Power System by Conventional and AI Based Controllers
Author Name:Ch. Durga Prasad
Synopsis:

The main objective of load frequency control (LFC) is to minimize the deviations in frequency and tie line power due to different load disturbances. This paper presents load frequency control of multi area interconnected power system with three single area systems using conventional controllers and artificial intelligence(AI) based techniques – Fuzzy and Artificial Neural Networks. The advantage of AI based controllers is that it can handle the non linear ties and at the same time it is faster than other controllers. Studies are carried out with Fuzzy and Fuzzy PID and compared with conventional controllers and finally concluded that AI based controllers gives better performance. The techniques are implemented in MATLAB/SIMULINK.