Unit Template Synchronous Reference Frame Theory Based Control Algorithm for DSTATCOM

This work discusses an experimental performance of a four-leg Distribution Static Compensator (DSTATCOM) using an adaptive filter based approach. It is used for estimation of reference supply currents through extracting the fundamental active power components of three-phase distorted load currents. This control algorithm is implemented on an assembled DSTATCOM for harmonics elimination, neutral current compensation and load balancing, under nonlinear loads. Experimental results are discussed, and it is noticed that DSTATCOM is effective solution to perform satisfactory performance under load dynamics.

An increasing growth of non-linear load in the three-phase four-wire distribution system, results in various power quality problems in the distribution system. Custom power devices (CPD) have been evolved to solve the power quality problems in the distribution system. Among the various custom power devices, Distribution Static Compensator (DSTATCOM) is one of the effective solutions for solving the power quality problems. This paper reveals about Distribution static compensator (DSTATCOM) for balancing of source currents, harmonic mitigation and neutral current compensation in three-phase four-wire distribution system. A synchronous reference frame (SRF) theory is projected for the control of DSTATCOM. Four-leg voltage source converter (VSC) with a dc capacitor is used as four-wire DSTATCOM. Here DSTATCOM is operated in load compensation mode. The first three-legs are used for balancing of source current and harmonic mitigation and the fourth leg is used for neutral current compensation. The compensation performance of DSTATCOM using the proposed control strategy is demonstrated using simulation results obtained from MATLAB/SIMULINK.

This paper presents single-phase P-Q theory for four-leg VSC based distributed static compensator (DSTATCOM) in the distribution system. The proposed DSTATCOM maintains unity power factor at source, zero voltage regulation, eliminates current harmonics, load balancing and neutral current compensation. The advantage of using four-leg VSC based DSTATCOM is to eliminate isolated/non-isolated transformer connection at point of common coupling (PCC) for neutral current compensation. The elimination of transformer connection at PCC with proposed topology will reduce cost of DSTATCOM. The single-phase P-Q theory control algorithm is used to extract fundamental component of active and reactive currents for generation of reference source currents which is based on indirect current control method. The proposed DSTATCOM is modelled and the results are validated with various consumer loads under unity power factor and zero voltage regulation modes in the MATLAB R2013a environment using simpower system toolbox.

Proportional and Integral (PI) controllers are usually accustomed for the control operation of Distribution Static Compensator (DSTATCOM) for the distribution system. However, since the system is very nonlinear and subject to numerous disturbances, the PI controlled DSTATCOM cannot offer optimum performance for various operation points. Additional controllers like the Instant Power Theory (IPT) supported fuzzy logic approach is needed for the DSTATCOM to supply adequate dynamic current control and to enhance power quality and stability of the distribution system. This paper presents the planning of fuzzy logic Controllers (FLC) of a DSTATCOM for improving power quality for a distribution system. The IPT based FLC for the DSTATCOM is used for improving the power quality and the dynamic performance of a distribution system is compared with a DSTATCOM controlled IPT based PI controller. The performances of the DSTATCOM controllers are evaluated throughout grid-side currents with linear and non-linear loads of the distribution system. Simulation results show that the DSTATCOM with IPT based FLC will improve the power quality by reducing reactive currents and harmonic currents with higher system dynamic performance than the DSTATCOM with IPT based standard PI controller.

The requirement of a robust and adaptive control algorithm in active filters is inevitable nowadays. In this paper, an ADAptive LINEar neuron (ADALINE) based Least Mean Square (LMS) control algorithm is proposed for a three-phase-four-wire (3P4W) distribution power system under unbalanced loading conditions. The proposed controller has a unique inbuilt characteristic to extract the fundamental active positive sequence component from an unbalanced load current. Particularly, the control algorithm is intended to calculate an adaptive and suitable amplitude for the three-phase reference source currents which are used for the switching pulse generation in the subsequent steps. Moreover, the Distribution STATic COMpensator (DSTATCOM) is performed to eliminate harmonic contents of supply current and harmful excessive neutral current in the system. Further, the DC-link voltage is regulated in order to reduce the power loss across the DSTATCOM, and to attain a balanced, high-quality power availability at the Point of Common Coupling (PCC). The proposed system is accomplished in the MATLAB2014a/Simulink, and a low power rated 3P4W DSTATCOM prototype incorporating with the dSPACE1104 real-time environment to verify the proposed control algorithm.

This paper discusses the unit template control strategy for load balancing and voltage regulation of induction generator based DG (Diesel generator) set for islanded system. The proposed system consists of DG set along with DSTATCOM (Distributed Static Compensator) and BESS (Battery Energy Storage System) is used for load balancing along with harmonics elimination and reactive power compensation. An isolated T-T Connected transformer is used to reduce size of two-leg VSC and also neutral current compensation. The battery on two-leg VSC (Voltage Source Converter) of DSTATCOM with BESS is able to supply active power when the load requirement is more than rating of DG set and battery can store energy when load requirement is less than DG set rating. The reference sources for two-leg VSC are estimated using unit template control strategy and this algorithm has quick dynamic response. The proposed DG set system with DSTATCOM is modeled in MATLAB R2009a along with Simulink and results are verified under three phase linear/non-linear loads.

Distribution static compensator (DSTATCOM) is a shunt compensation device that is generally used to solve power quality problems in distribution systems. In an all-electric ship power system, power quality issues arise due to high-energy demand loads such as pulse loads. This paper presents the application of a DSTATCOM to improve the power quality in a ship power system during and after pulse loads. The control strategy of the DSTATCOM plays an important role in maintaining the voltage at the point of common coupling. A novel adaptive control strategy for the DSTATCOM based on artificial immune system (AIS) is presented in this paper. The optimal parameters of the controller are first obtained by using the particle swarm optimization algorithm. This provides a sort of innate immunity (robustness) to common system disturbances. For unknown and random system disturbances, the controller parameters are modified online, thus providing adaptive immunity to the control system. The performance of the DSTATCOM and the AIS-based adaptive control strategy is first investigated in MATLAB-/Simulink-based simulation platform. It is verified through a real-time ship power system implementation on a real-time digital simulator and the control algorithm on a digital signal processor.

This paper discusses an Amplitude Adaptive Filter (AAF) based control algorithm for distribution static compensator (DSTATCOM) in three-wire supply system. The DSTATCOM is used in the power factor correction mode for removal of current-based power quality issues such as source-side current harmonics, poor power factor along with load balancing. An AAF not only computes the amplitude and frequency of the signal but it is also adapting the amplitude of the signal under variations. The estimated amplitude is employed to create the reference source currents to generate gating pulses. Tests were carried out using real time digital simulators (RT-LAB) to validate the function of DSATCOM in distribution system.

Large penetration of PV in a microgrid connected distribution system impacts the weak utility distribution system by creating various power quality (PQ) problems such as voltage sag or swell, unbalance, harmonics and DC current injection etc. These power quality (PQ) issues and they are broadly classified as current related PQ issues and voltage related PQ issues. The current related issues are mitigated by one of the custom power device connected in parallel namely distribution static compensator (DSTATCOM), by operating in current controlled mode (CCM). The dynamic voltage restorer (DVR) is another custom power device (CPD) for mitigating voltage related PQ problems. It is reported in literature that, a suitable modification of a DSTATCOM can achieve the capability to compensate voltage disturbances also. A multiple functions of DSTATCOM is thus achieved by operating the device so as to mitigate the current and voltage related PQ issues. Thus a multi-functional control strategy allow DSTATCOM to compensate voltage and current related PQ problems. This paper presents a hybrid DSTATCOM which can be used in highly PV penetrated distribution system to control the voltage and current related PQ issues. The topology uses a suitably designed foreign inductor, connected between the grid and load. A dynamic reference load voltage generation algorithm using instantaneous symmetric component theory (ISCT) is presented. The simulation is done with real time voltage level using MATLAB/SIMULINK.

<p class="Abstract"><span lang="EN-US">Voltage sags are the most common power quality disturbances in electrical facilities. It may cause malfunction in sensitive equipment and process interruption. The distribution static compensator (DSTATCOM) is a device that can compensate voltage sags by injecting reactive power into distribution system. This paper shows the influence on voltage sags characteristics by the presence of twelve-pulse DSTATCOM in the modified IEEE-13 distribution system. The analysis is performed by means of a random generation of disturbances using a MATLAB routine to identify the critical buses of the test system. Further, the DSTATCOM model taking advantage of the available elements from ATP/EMTP software is described. Simulations show that when DSTATCOM is placed directly to affected bus it is possible to obtain a complete mitigation of the voltage sag. Finally, the relation between the reactive power injected by DSTATCOM, the type of voltage sag and the location of affected bus is considered.</span></p>

This paper deals with a software phase locked loop (SPLL) based control algorithm for a three phase distribution static compensator (DSTATCOM) for power quality improvement under linear/nonlinear loads in a distribution system. In this control approach, amplitude of fundamental active and reactive power components of load currents is extracted for estimation of reference source currents. The DSTATCOM is modeled in the Matlab environment using Simulink and Sim Power System (SPS) toolboxes. Matlab based developed model of DSTATCOM is used to simulate its performance. Simulated performance of DSTATCOM is found satisfactory under time varying and unbalanced linear and nonlinear consumer loads.

In this paper a new control algorithm has been proposed to control the power flow of the utility grid which has been penetrated by renewable energy sources (RES). The proposed control algorithm ensures utility grid to undergo minimum power changes. The hybrid energy storage system consisting of high power density element such as super capacitor and high energy density element such as battery storage has been used to compensate the residual power. The proposed control algorithm has been implemented to the distribution static compensator (DSTATCOM) to achieve multiple goals, such as integrating photo voltaic (PV) to the utility grid, compensating the reactive power and current related power quality issues and the power flow balancing. The balancing of the energy flows and current related power quality issues have been compensated using a DSTATCOM. The proposed configuration of the system has been implemented in MATLAB/Simulink and the corresponding simulation results are being presented in the manuscript.

LCL filter with passive damping for DSTATCOM using PI and HC regulators in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si77.gif" display="inline" overflow="scroll"><mml:mi>d</mml:mi><mml:mi>q</mml:mi><mml:mn>0</mml:mn></mml:math>current controller for load compensation

This paper presents the modelling and implementation of a three-phase DSTATCOM (Distribution Static Compensator) using an efficient control algorithm for power conditioning. This is one of an effective way for harmonic suppression, load balancing and reactive power compensation at distorted PCC (Point of Common Coupling) voltages under nonlinear loads. It is hoped at providing a broad perspective on the status of DSTATCOM control methods to researchers and application engineers dealing with harmonic cancellation issues. The proposed scheme consists of a zigzag transformer, double tuned filter, rectifiers, voltage source converter of the DSTATCOM. A fuzzy logic controller & traditional PI controller are used to control the neutral current & dc link voltage under both balanced & unbalanced loading conditions. Simulation studies are showing the better performance of three-phase DSTATCOM using MATLAB SIMULINK & power system toolboxes.

This paper proposes a modified four-leg distribution static compensator (DSTATCOM) topology for compensation of unbalanced and nonlinear loads in three-phase four-wire distribution system. DSTATCOM, connected in parallel to the load, supplies reactive and harmonic powers demanded by unbalanced nonlinear loads. In this proposed topology, the voltage source inverter (VSI) of DSTATCOM is connected to point of common coupling (point of interconnection of source, load, DSTATCOM) through interface inductor and series capacitance, unlike the conventional topology which consists of interface inductor alone. Load compensation with a lower value of input DC link voltage of VSI is possible in this modified topology compared to conventional topology. A comparative study on modified and conventional topologies in terms of voltage rating of inverter power switches, switching losses in VSI and power rating of input DC capacitor of VSI is presented. The detailed design aspects of DC link capacitor and interface series capacitor are also presented. The reference filter currents are generated using instantaneous symmetrical component theory and are tracked using hysteresis current control technique. A detailed simulation study is carried out, to compare the compensation performances of conventional, modified topologies using PSCAD simulator and experimental studies are done to validate the simulation results.