In this paper, the theory of instantaneous symmetrical components is applied to explore various control strategies of load compensation, under different supply voltages. When the supply voltages are balanced and sinusoidal, all of these strategies converge to the same compensation characteristics. However, when the supply voltages are not balanced sinusoids, these control strategies result in different degrees of compensation in harmonics, power factor, neutral current, and compensator ratings. These control strategies are discussed in detail and a comparative study of their performance in terms of the rms value, total harmonic distortion, power factor of source currents, and compensator ratings is presented. Based on this study, it is possible to select the best strategy to meet the required load compensation characteristics for available supply voltages. A three-phase four-wire distribution system supplying an unbalanced and nonlinear load is considered for simulation study. The detailed simulation results using MATLAB are presented to support the proposed compensation strategies. © 2008 IEEE.

Mahesh Kumar Mishra

Department of Electrical Engineering

Active filters

ELECTRIC FILTERS

Electric network analysis

Electric power factor

Harmonic analysis

MATLAB

OPTICAL FILTERS

Wave filters

Active power filter (APF)

INSTANTANEOUS SYMMETRICAL COMPONENT THEORY

Load compensation

PERFECT HARMONIC CANCELLATION

UNBALANCED AND DISTORTED SUPPLY VOLTAGES

Unity power factor

Electric power factor correction

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Control Strategies for Load Compensation Using Instantaneous Symmetrical Component Theory Under Different Supply Voltages

IEEE Transactions on Power Delivery

This paper proposes a new three-leg voltage source inverter (VSI) based distribution static compensator (DSTATCOM) topology to compensate unbalanced and nonlinear loads in low voltage three phase four wire distribution systems. The proposed topology uses a three-leg VSI with a single DC storage capacitor and an additional capacitor which is connected between negative DC bus to the system neutral. As the proposed topology uses a single DC link capacitor, the DC voltage balancing issues associated with the popular split capacitor neutral clamped VSI topology is avoided. Moreover, the topology is able to compensate neutral current without using four-leg inverter topologies. Analysis and modelling of the proposed topology is explained in detail. Simulation studies are carried out to verify the performance of the proposed schemes and results are presented. © 2014 IEEE.

India International Conference on Power Electronics, IICPE

A three-leg inverter based DSTATCOM topology for compensating unbalanced and nonlinear loads

This paper presents a dual voltage source inverter (DVSI) scheme to enhance the power quality and reliability of the microgrid system. The proposed scheme is comprised of two inverters, which enables the microgrid to exchange power generated by the distributed energy resources (DERs) and also to compensate the local unbalanced and nonlinear load. The control algorithms are developed based on instantaneous symmetrical component theory (ISCT) to operate DVSI in grid sharing and grid injecting modes. The proposed scheme has increased reliability, lower bandwidth requirement of the main inverter, lower cost due to reduction in filter size, and better utilization of microgrid power while using reduced dc-link voltage rating for the main inverter. These features make the DVSI scheme a promising option for microgrid supplying sensitive loads. The topology and control algorithm are validated through extensive simulation and experimental results. © 2010-2012 IEEE.

IEEE Transactions on Sustainable Energy

A Grid-Connected Dual Voltage Source Inverter with Power Quality Improvement Features

This study proposes a new three-leg voltage source inverter (VSI)-based distribution static compensator (DSTATCOM) topology to compensate unbalanced and non-linear loads in low-voltage three-phase four-wire distribution systems. The proposed topology uses a three-leg VSI with a single DC storage capacitor. This scheme has an additional small AC capacitor which is connected between negative DC bus to the system neutral. As the proposed topology uses a single DC-link capacitor, the DC voltage balancing issues associated with the popular split capacitor neutral clamped VSI topology is avoided. Moreover, the topology is able to compensate neutral current without using four-leg inverter topology. Analysis and modelling of the proposed topology is explained in detail. Simulation studies are carried out to verify the performance of the proposed scheme and results are presented. The performance of the new topology has been compared with conventional three-leg two level split capacitor VSI-based DSTATCOM topology. Results are also experimentally verified on a laboratory prototype of DSTATCOM. © The Institution of Engineering and Technology 2015.

IET Power Electronics

Three-leg inverter-based distribution static compensator topology for compensating unbalanced and non-linear loads

This paper presents a power sharing control algorithm for parallel grid interactive multifunctional voltage source inverters (PGMVSIs) which are connected to distributed renewable energy sources. The main objective of this scheme is to get proportional power sharing among PGMVSIs, so as to make the grid current balanced sinusoidal and at unity power factor. The control algorithm is derived using instantaneous symmetrical component theory (ISCT) to ensure a proper sharing of active, reactive, unbalance and harmonic power among parallel inverters. This scheme requires a central controller and communication among inverters in contrary to the droop control based techniques. However, the proposed control scheme has perfect decoupling of active and reactive power sharing, proportional unbalance and harmonic power sharing, and a very good dynamic response. The steady state and transient performance of the proposed control strategy have been verified through detailed simulation. © 2014 IEEE.

2014 IEEE International Conference on Power Electronics, Drives and Energy Systems, PEDES 2014

Current sharing control strategy of parallel inverters using instantaneous symmetrical component theory

This paper proposes a new configuration of UPQC that consists of battery and ultracapacitor connected to the DC link through DC/DC converters for compensating voltage and current related PQ problems. The main objective of this configuration is to enable UPQC to mitigate voltage interruption and reduce battery stress with the help of ultracapacitor. The proposed UPQC can compensate current harmonics, current unbalance, load reactive power, voltage sag, voltage swell and voltage interruption. The Shunt inverter inject currents to ensure a balanced, sinusoidal and unity power factor PCC current except under source voltage interruption during which shunt inverter operates in voltage control mode for maintaining balanced and sinusoidal load voltage. The Series inverter inject voltages to ensure a balanced and sinusoidal load voltage except under voltage interruption during which series inverter is isolated from the system. The combination of battery and ultracapacitor yield a power source having both high energy density and power density. Battery delivers average load power during voltage interruption while ultracapacitor takes all the load fluctuating power. The performance of the proposed UPQC with battery-ultracapacitor storage system have been verified through simulation results. © 2014 IEEE.

Control and operation of unified power quality Conditioner with battery-ultracapacitor energy storage system

In this paper, a novel control algorithm is proposed to compensate the unbalance and non-linear loads in threephase four-wire system using active power filter. The algorithm results in balanced and sinusoidal source currents under balanced as well as unbalanced and distorted three-phase supply voltages. The algorithm makes the use of the positive sequence extraction of the supply voltage and the theory of instantaneous symmetrical components. To illustrate the concept, a three-phase four-wire system with unbalance and nonlinear load is considered for compensation and detailed simulation results are presented.

IEEE Region 10 Annual International Conference, Proceedings/TENCON

A novel three-phase active power filter control algorithm with unbalanced and distorted supply voltages

i-manager's Journal on Power Systems Engineering

MULTI AREA LOAD FREQUENCY CONTROL OF A HYBRID POWER SYSTEM WITH ADVANCED MACHINE LEARNING CONTROLLER: A CASE STUDY OF ANDHRA PRADESH

Cancer Research Frontiers

The Lymphedema Evaluation in Gynecological cancer Study (LEGS): design of a prospective, longitudinal, cohort study

Analysis of Three-Phase Systems With Neutral Under Distorted and Unbalanced Conditions in the Symmetrical Component-Based Framework

This paper presents a simple control algorithm for a shunt active filter for compensation of harmonics and reactive power under nonsinusoidal supply voltage conditions. Under nonsinusoidal supply conditions, any attempt to achieve unity power factor results in a nonsinusoidal current, which increases the total harmonic distortion (THD). On the other hand, attempt at getting harmonic free current may not yield unity power factor because of the harmonics present in the voltage waveform. The proposed algorithm optimizes this trade-off using the Lagrange multiplier technique and achieves the best compromise. It does not employ the normally used p-q theory and is applicable to both single phase and three phase systems. With the proposed technique, it is possible to obtain an optimized power factor satisfying the specified THD limit. The algorithm has been tested under various supply and load conditions using MATLAB simulations and validated with an experimental prototype based on DSP TMS320LF2407A. © 2005 IEEE.

A novel, DSP based algorithm for optimizing the harmonics and reactive power under non-sinusoidal supply voltage conditions

Control strategies for load compensation using instantaneous symmetrical component theory under different supply voltages

Journal	IEEE Transactions on Power Delivery
ISSN	08858977
Open Access	No