N. V. Srikanth

Unified Philips-Heffron Model of Multi-Machine Power System Equipped with PID Damping Controlled SVC for Power Oscillation Damping

This paper presents a novel approach to small signal stability enhancement using static VAR compensator (SVC) with PID damping controller. Static VAR compensator is proven the fact that it improves the dynamic stability of power systems apart from reactive power compensation; it has multiple roles in the operation of power systems. The supplementary auxiliary control signals to SVC play a vital role in mitigating the rotor electro-mechanical low frequency oscillations. A proportional- integral-derivative (PID) type controller is designed using the generator speed deviation, as a modulated signal to SVC, to generate the desired damping, is proposed in this paper. The PID damping controller for SVC is used to improve the dynamic performance of power system by reducing the steady-state error and for fast settling. The simulations are carried out for Multi- machine power system at different operating conditions.

Performance of SVPWM based vector controlled HVDC light transmission system under balanced fault condition

The recent developments in power electronics technology have lead to the improvements of insulated gate bipolar transistor (IGBT) based Voltage source converter High voltage direct current (VSC HVDC) transmission systems. These are also commercially known as HVDC Light transmission systems, which are popular in renewable, micro grid, and electric power systems. Out of different pulse width modulation (PWM) schemes, Space vector PWM (SVPWM) control scheme finds growing importance in HVDC Light applications because of its better dc bus utilization. In this paper, SVPWM scheme is utilized to control the HVDC Light system in order to achieve better DC bus utilization, harmonic reduction, and for reduced power fluctuations. The simulations are carried out in the MATLAB/SIMULINK environment and the results are provided for steady state and dynamic conditions. Finally, the performance of SVPWM based vector controlled HVDC Light transmission system is compared with sinusoidal pulse width modulation (SPWM) based HVDC Light system in terms of output voltage and total harmonic distortion (THD).

An adaptive neuro fuzzy inference system controlled space cector pulse width modulation based HVDC light transmission system under AC fault conditions

In HVDC Light transmission systems, converter control is one of the major fields of present day research works. In this paper, fuzzy logic controller is utilized for controlling both the converters of the space vector pulse width modulation (SVPWM) based HVDC Light transmission systems. Due to its complexity in the rule base formation, an intelligent controller known as adaptive neuro fuzzy inference system (ANFIS) controller is also introduced in this paper. The proposed ANFIS controller changes the PI gains automatically for different operating conditions. A hybrid learning method which combines and exploits the best features of both the back propagation algorithm and least square estimation method is used to train the 5-layer ANFIS controller. The performance of the proposed ANFIS controller is compared and validated with the fuzzy logic controller and also with the fixed gain conventional PI controller. The simulations are carried out in the MATLAB/SIMULINK environment. The results reveal that the proposed ANFIS controller is reducing power fluctuations at both the converters. It also improves the dynamic performance of the test power system effectively when tested for various ac fault conditions.

A novel approach to dynamic stability enhancement using PID damped fuzzy susceptance controlled SVC

This paper presents a novel approach to dynamic stability enhancement using PID damped fuzzy susceptance controlled static VAR compensator (SVC). Static VAR compensator is proven the fact that it improves the dynamic stability of power systems apart from reactive power compensation; it has multiple roles in the operation of power systems. The additional auxiliary control signals to SVC play a very important role in mitigating the rotor electromechanical low frequency oscillations. A proportional-integral-derivative (PID) type controller is designed using the generator speed deviation, as a modulated signal to SVC, to generate the desired damping, is proposed in this paper. The fuzzy logic controller is considered to generate the required incremental firing angle delays for SVC. The simulations are carried out for multi-machine power system at different operating conditions.

A comparative study of SPWM and SVPWM controlled HVDC Light systems

Recent upgrades in power electronics technology have lead to the improvements of insulated gate bipolar transistor (IGBT) based Voltage source converter High voltage direct current (VSC HVDC) transmission systems. These are also commercially known as HVDC Light systems, which are popular in renewable, micro grid, and electric power systems. Out of different pulse width modulation (PWM) schemes, Space vector PWM (SVPWM) control scheme finds growing importance in power system applications because of its better dc bus utilization. In this paper, SVPWM scheme is utilized to control the HVDC Light system in order to achieve better DC bus utilization, harmonic reduction, and for reduced power fluctuations. The simulations are carried out in the MATLAB/ SIMULINK environment and the results are provided for steady state and dynamic conditions in comparison with the existing sinusoidal PWM (SPWM) controlled HVDC light system. Finally, it is shown that SVPWM control enables the output voltage by nearly 15% and low Total harmonic distortion (THD) as compared to SPWM control.

Two-quadrant clamping inverter scheme for three-level open-end winding induction motor drive

This article proposes a space-vector based pulse width modulation (SVPWM) scheme for a three-level dual-inverter-fed open-end winding induction motor drive. The proposed method introduces clamping of one inverter for 180° span of the rotation of the reference space vector. The proposed scheme neither requires sector identification nor lookup tables for the generation of the gating pulses. The switching pattern adopted in the present work ensures alternative clamping and switching modes every 180° for both the inverters. In the present scheme, the zero sequence currents are denied a path by using isolated power supplies. The proposed switching strategy envisages two-quadrant clamping of the inverters which results in lowering of the losses that occur in power electronic switches. Simulation studies have been carried out for the proposed SVPWM strategy using MATLAB/Simulink.

A hybrid approach for optimal location and capacity of UPFC to improve the dynamic stability of the power system

This paper proposes the Firefly algorithm and Cuckoo Search (CS) algorithm based optimal location and the capacity of UPFC to improve the dynamic stability of the power system.Here, the FA technique optimizes the maximum power loss line as the suitable location of the UPFC. The affected location parameters and dynamic stability constraints are restored into secure limits using the optimum capacity of the UPFC, which in turn, has been optimized with reduced cost by using the CS algorithm. The attained capacity of the UPFC has been located in the affected location and the power flow of the system is analyzed.The proposed method is implemented in the MATLAB/Simulink platform and tested under IEEE 30 and IEEE 14 standard bench mark system. The advantage of the proposed method is capability and robustness to solve the complex optimization problem.In the results, system bus voltage, power loss, real and reactive power flow were analyzed. Then the proposed methods effectiveness was tested by the comparison analysis with the ABC-GSA, GSA-BAT & BAT-FF algorithms. The comparison results proved that the proposed method is the most effective technique to maintain the dynamic stability of the power system, which is competent over the other techniques. In this document, the Firefly Algorithm (FA) and Cuckoo Search (CS) algorithm based on optimal location and the capacity of UPFC to improve the dynamic stability of the power system are proposed. The novelty of the proposed method is exemplified in the improved searching ability, random reduction and reduced complexity. In this regard, the generator fault affects the system dynamic stability constraints such as voltage, power loss, real and reactive power. Here, the FA technique optimizes the maximum power loss line as the suitable location of the UPFC. The affected location parameters and dynamic stability constraints are restored into secure limits using the optimum capacity of the UPFC, which in turn, has been optimized with reduced cost by using the CS algorithm. The attained capacity of the UPFC has been located in the affected location and the power flow of the system analyzed. The proposed method is implemented in the MATLAB/Simulink platform and tested under IEEE 30 and IEEE 14 standard bench mark system. The proposed method performance is evaluated by comparison with those of different techniques such as ABC-GSA, GSA-Bat, Bat-FA and CS algorithms. The comparison results invariably prove the effectiveness of the proposed method and confirm its potential to solve the related problems.

Optimization of UPFC location and capacity to improve the stability using ABC and GSA algorithm

In this paper optimal location and capacity of Unified Power Flow Controller to improve the power system stability using hybrid technique composed of ABC-GSA algorithms is proposed. Here, the maximum power loss bus is identified as the most suitable location for connecting the UPFC under generator outage conditions. The optimum location has been determined using the Artificial Bees Colony (ABC) algorithm. Depending on the violated power flow quantities the Gravitational Search Algorithm (GSA) optimize the required capacity of the UPFC to recover the initial stable operating condition. The proposed work is implemented in the MATLAB platform and the performance is analyzed by comparison with individual algorithms ABC and GSA. The comparison results demonstrate the superiority of the proposed Hybrid approach and confirm its potential to solve the problem.

An Adaptive Coordinated Control for an OffshoreWind Farm Connected VSC Based Multi-TerminalDC Transmission System

Abstract The voltage source converter (VSC) based multiterminal high voltage direct current (MTDC) transmission system is an interesting technical option to integrate offshore wind farms with the onshore grid due to its unique performance characteristics and reduced power loss via extruded DC cables. In order to enhance the reliability and stability of the MTDC system, an adaptive neuro fuzzy inference system (ANFIS) based coordinated control design has been addressed in this paper. A four terminal VSC-MTDC system which consists of an offshore wind farm and oil platform is implemented in MATLAB/ SimPowerSystems software. The proposed model is tested under different fault scenarios along with the converter outage and simulation results show that the novel coordinated control design has great dynamic stabilities and also the VSC-MTDC system can supply AC voltage of good quality to offshore loads during the disturbances.

ANFIS based coordinated control for an offshore wind farm connected VSC MTDC system

Offshore wind farms are becoming an attractive solution for wind power in many developed countries. The voltage source converter (VSC) based multi-terminal high voltage direct current (MTDC) transmission system is an attractive technical option to integrate these offshore wind farms with the onshore grid due to its unique performance characteristics and reduced power loss via extruded DC cables. In this paper, an adaptive neuro fuzzy inference system (ANFIS) based coordinated control design has been addressed for MTDC system in order to enhance the reliability and to balance the power. A four terminal VSC-MTDC system which consists of an offshore wind farm and oil platform is implemented in MALAB/SimPower Systems software. The proposed model is tested under different fault scenarios and simulation results show that the novel coordinated control design has great dynamic stabilities and also the VSC-MTDC system can supply Ac voltage of good quality to offshore loads during the disturbances.