Sangram Keshari Routray

A robust control strategies to improve transient stability in VSC-HVDC based interconnected power systems

This paper presents a robust non linear sliding mode controller(SMC) for VSC-HVDC transmission link in parallel with an AC transmission line connecting a synchronous generator to infinite bus. A non linear sliding mode controller has been proposed to provide voltage support by means of reactive control at both ends; to damp power oscillations and improve transient stability by controlling either active or reactive power, and to control the power flow through the HVDC link. The proposed control scheme is tested under several system disturbances like changes in short-circuit ratio, faults on the converter and inverter buses. Based upon the time domain simulations in MATLAB/SIMULINK environment, the proposed controller is tested and its better performance is shown compare with the PI controllers whose gains are optimized with teaching learning optimization technique. The proposed controller improves voltage stability, damping of power oscillations and transient stability.

Non-linear control and stabilisation of VSC-HVDC transmission system based on Type-2 fuzzy sliding mode control

This paper presents a robust non-linear hybrid controller based on Type-2 fuzzy and sliding mode control strategy for VSC-HVDC transmission link, which inherits the benefits of these two methods. The interval Type-2 fuzzy (IT2FSMC) is used to handle the uncertainties to enhance the real time performance. The sliding mode control combines with the fuzzy system to compensate the influence of un-modelled dynamics and chattering phenomena on the system response, and also to improve the robustness of the reaching phase of the sliding mode control (SMC). The effectiveness of the proposed controller is demonstrated through digital simulation studies using MATLAB/SIMULINK software package. The simulation results show that the proposed controller contribute significantly towards improving the damping behaviour of the VSC-HVDC system with regard to parameter variations and external load disturbances compared to conventional PI controller under a wide range of operating conditions.

Damping of interarea oscillations of a wind farm based multimachine power system using an unified Power Flow Controller

An adaptive second order sliding mode control strategy is proposed for of the Series Synchronous Static Compensator (SSSC) of the Unified Power Flow Controller (UPFC) which is installed in a multimachine power network penetrated with a Doubly Fed Induction Generator (DFIG) based wind power. The proposed controller utilizes the instantaneous power components of the SSSC instead of the conventional current or torque components (thus the dynamics of the phase lock loops (PLL) is avoided) and has been made to adapt according to the diverse operating conditions of the network. This feature has made the proposed controller to be more significant (in terms of improvement of the transient stability) as compared to the conventional techniques as both the inter area as well as local oscillations have been improved. The overall power system network has been modeled in MATLAB/Editor environment, and the proposed controller has been investigated for both lower and higher wind penetration conditions and the results obtained are satisfactory.

An MIWO based approach of power system transient stability enhancement with STATCOM

The main objective of this paper is to investigate the enhancement of damping power system oscillations under various operating conditions with static synchronous compensator (STATCOM). The design of STACOM controller is formulated as an optimization problem and an modified invasive weed optimization (MIWO) algorithm is employed to search for optimal controller parameters settings. In this paper, a modified IWO algorithm with parallel probabilistic search method is applied for better convergence of the optimization process. The proposed controller is evaluated on a single machine infinite bus (SMIB) power system with STATCOM installed at mid point. To assess the effectiveness of the proposed design, eigen value analysis as well as time domain simulations are carried out to compare with results of genetic algorithm technique within MATLAB/SIMULINK environment.

Design of Takagi-Sugeno fuzzy controller for VSC-HVDC parallel AC transmission system using differential evolution algorithm

This paper presents an optimised Takagi-Sugeno (TS) fuzzy controller using differential evolution (DE) technique for a VSC-HVDC transmission link with a parallel AC line, through the analysis on voltage source converter (VSC) equation in d-q reference frame. The state space model for a VSC-HVDC transmission link is formulated. The controller is designed to provide high dynamic performance and complete decouple control of active and reactive power. The DE technique is used to optimise the rule consequent parameters of a TS fuzzy controller. The effectiveness and performance of the proposed controller is demonstrated though digital simulation studies on a VSC-HVDC power system, using MATLAB/SIMULINK software package. The simulation results and the comparison with conventional PI and simple fuzzy logic controller show that proposed controller contributes significantly towards improving the transient characteristics of the VSC-HVDC system under a wide range of operating conditions under severe disturbances.

Optimal design of PID controller for AVR in a multi machine power system using modified PSO and fire fly optimization technique

The stability of power system when subjected to disturbances is one of the most important challenges. The Automatic voltage regulator (AVR) is used to enhance the performance of power system due to its acceptability to reduce damping. In this work the problem is formulated as a single objective optimization function to tune the AVR parameter gains of the PID controller. Here the firefly optimization algorithm which is found robustly for this type of problems is selected as a tool to find the optimum solution. Comprehensive simulations are carried out on a four machine power system under various operating conditions. The results are obtained under different fault conditions with FF optimization technique and compared the same with MPSO. At last it is observed that the FF technique performs better in damping the overshoot and settling time.

Power quality disturbance recognition using hybrid signal processing and machine intelligence techniques

This paper presents two novel approaches for power quality (PQ) event classification. It is a two stage system in which optimal features that characterise the complete signal behaviour are extracted in the first stage and in second stage, based on these features various disturbance waveforms are classified. In the first classifier, a hybrid approach between S-transform and decision tree (DT) is presented. In the second classifier, the S-transform (ST) technique is integrated with neural network (NN) model with multilayer perceptron. Power system suffers from different PQ events such as sag, swell, momentary interruptions, impulsive transients, notch, spike, harmonics and also combination of the above with noise. The above-mentioned events comprise high-frequency and low-frequency components. Thus, it is difficult to classify these PQ events using traditional approaches. Both the classification methods derive various statistical parameters of eight types of single power disturbance and two types of complex...