In this paper, load compensation techniques under unbalanced and distorted voltages have been discussed. Two kinds of compensation methods are considered. In the first category, synchronous detection and modified equal current strategies are used under the unbalanced but sinusoidal source voltages. In the second method, load compensation based on instantaneous symmetrical component theory with positive sequence extraction is proposed and is shown to work under unbalanced and the non-sinusoidal source voltages. To support the proposed method, a 440 V (L-L) three-phase, four-wire distribution system is considered. The compensator is realized using a three-phase voltage source inverter (VSI) operated in the current control mode. Detailed digital simulation and experimental results are presented to validate the approach. © 2006 IEEE.

Mahesh Kumar Mishra

Department of Electrical Engineering

Computer simulation

Electric distortion

Electric inverters

Electric potential

INSTANTANEOUS SYMMETRICAL COMPONENT THEORY

MODIFIED EQUAL CURRENT STRATEGIES

SYNCHRONOUS DETECTION

Voltage source inverter

Electric load management

Fulltext

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

A Novel Method of Load Compensation Under Unbalanced and Distorted Voltages

IEEE Transactions on Power Delivery

This paper presents Distribution Static Compensator (DSTATCOM) for compensation of unbalanced nonlinear load with dq0 current controller (using proportional integrator and harmonic compensation regulators) and Sinusoidal Pulse Width Modulation (SPWM) switching. The dq0 current controller is implemented in Synchronous Reference Frame (SRF) rotating at fundamental frequency and consists of Harmonic Compensation (HC) regulator (realized by sum of Sinusoidal Signal Integrators (SSI)) in parallel to Proportional Integrator (PI) regulator. The SSI provides high gain to specified tuned harmonic frequency and helps in improving filter current tracking performance for harmonic load current compensation. Each SSI in fundamental rotating dq0 reference frame can simultaneously compensate for two load current harmonics and thereby reducing the computational effort compared to SSI in stationary reference frame. Neutral current compensation, which is required for compensating unbalance in load, is carried out through 0-axis controller. SPWM switching strategy results in switching of inverter switches at constant frequency. This will simplify the design of inverter output filter (L/LC), reduces stress on switches and switching noise. Simulation studies of DSTATCOM load compensation using dq0 current controller with interface L and LC filters is carried out in Matlab/Simulink and the corresponding results are presented. Experimental studies are carried out on three phase DSTATCOM prototype using dSPACE 1104 with Matlab Real Time Interface (RTI). © 2014 Published by Elsevier Ltd.

International Journal of Electrical Power and Energy Systems

SRF based current controller using PI and HC regulators for DSTATCOM with SPWM switching

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 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 Distribution Static Compensator (DSTATCOM) with interface inductor-capacitor-inductor (LCL) filter controlled using dq0 current controller and Sinusoidal Pulse Width Modulation (SPWM) switching for compensation of unbalanced nonlinear load. Voltage Source Inverter (VSI) of DSTATCOM, connected at the point of common coupling (PCC) through interface filter, injects currents corresponding to load reactive and harmonic powers. These currents consist of switching frequency ripples. LCL filter has superior switching ripple attenuation capability compared to L filter. Moreover, this can be achieved with small value of overall LCL filter inductance than L filter. However, one major concern with LCL filter is its resonating frequency (determined from its L, C, L values), which can create resonance currents and results in improper load compensation. Therefore, in the present study, a proper design of LCL filter for high switching ripple attenuation along with passive damping and proper dq0 current controller are presented. The dq0 current controller is implemented in Synchronous Reference Frame (SRF) rotating at fundamental frequency and consists of Harmonic Compensation (HC) regulator (realized by sum of Sinusoidal Signal Integrators (SSI)) in parallel to Proportional Integrator (PI) regulator. SSI provides high gain to specified tuned harmonic frequency and helps in minimizing filter current tracking error for harmonic load current compensation. Neutral current compensation, which is required for compensating unbalance in load, is carried out through 0-axis controller. SPWM strategy generates constant frequency gating pulses for VSI switches. This will simplify the design of interface LCL filter, reduces stress on switches and switching noise. A Matlab/Simulink model of LCL filter DSTATCOM is developed and detailed simulation results of load compensation are presented. Experimental validation of proposed scheme is done on a three phase DSTATCOM prototype using dSPACE 1104 with Matlab Real Time Interface (RTI). © 2015 Elsevier Ltd.

Sustainable Energy, Grids and Networks

LCL filter with passive damping for DSTATCOM using PI and HC regulators in dq0 current controller for load compensation

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

Load compensating dstatcom in weak ac systems

Electric Power Systems Research

A new compensation algorithm for balanced and unbalanced distribution systems using generalized instantaneous reactive power theory

IEE Proceedings - Generation, Transmission and Distribution

Unified shunt compensator algorithm based on generalised instantaneous reactive power theory

The use of instantaneous symmetrical components for balancing a delta connected load and power factor correction

IEEE Transactions on Power Electronics

Three-phase four-wire shunt active filter control strategies

A novel method of load compensation under unbalanced and distorted voltages

Journal	IEEE Transactions on Power Delivery
ISSN	08858977
Open Access	Yes