Dynamic Voltage Restorer Research Articles

WITHDRAWN: Optimized FOPID controller for power quality enhancement between feeders using interline dynamic voltage restorer

This paper proposes a novel control scheme for Interline dynamic voltage restorer (IDVR). The optimized fractional order PID (FOPID) controller is used in this work for power quality enhancement such as voltage regulation, harmonics distortion reduction, voltage sag and swells compensation, fault compensation etc. The gain parameters of FOPID controller are tuned by gravitational search algorithm (GSA). The performance of the suggested controller is evaluated by contrasting it with other optimization technique such as particle swarm optimization and cuckoo-search optimization algorithm. These simulation results represents that FOPID with GSA works better than the other techniques in terms of power quality enhancement.

Modelling Analysis and Simulation of Dynamic Voltage Restorer in the Distribution System

Modelling Analysis and Simulation of Dynamic Voltage Restorer in the Distribution System

Performance of DVR Using Optimized PI Controller Based Gradient Adaptive Variable Step LMS Control Algorithm

A custom power device known as dynamic voltage restorer (DVR) has been investigated to operate a distribution system at its desired performance. The distribution system with voltage-related power quality issues in the supply side has been addressed through this article using DVR. Four different grid disturbances, such as voltage sag, swell, unbalances, and distortions, have been taken into account while testing the DVR capability. DVR has been controlled using optimized proportional and integral (PI) gains integrated with gradient adaptive variable learning rate least mean square control algorithm. Adaptiveness of variable step-size in LMS makes the control robust in case of dynamics in the system, which assures better performance. Also, the other major contribution of this article is the implementation of optimization-based self-tuning PI gains in the proposed control. The evaluation of optimizer in estimating the PI gains is presented in terms of the response of dc-link voltage DVR. The simulation work of proposed control algorithms on DVR has been done and satisfactory results are found. For the experimental validation, d-SPACE made Micro Lab Box is used as control processor, and both dynamic and steady-state results are discussed for its effectiveness.

Voltage quality improvement in electrical distribution networks using dynamic voltage restorers: design, simulation and experimental tests of a robust controller

This paper presents a simulation and implementation of a proportional integral (PI) and adaptive neuro-fuzzy inference system (ANFIS) control scheme of single-phase dynamic voltage restorer (DVR) for the mitigation of load voltage sag, swell and harmonics. The objective of the control strategies is to regulate the voltage of the DVR via an injection transformer to compensate for the voltage required and maintain the load voltage at a constant value. However, the conventional compensation techniques are grouped only on the load voltage and the DVR itself. The aim is to regulate the injection voltage of the DVR to compensate the grid voltage via the injection transformer in addition to maintaining the load voltage stable. These methods have been adapted to sinusoidal references and is resistant to sags, swells and harmonics. The proposed control strategies of the DVR are initially evaluated in simulations under MATLAB/Simulink and then validated on a laboratorial prototype of the single-phase DVR. n in-depth analysis across different controllers would show the performance and their robustness in mitigating network power quality issues. The robustness of the proposed ANFIS controller is examined by comparative studies with the PI controller. We notice that the proposed ANFIS controller was able to obtain a lower total harmonic distortion than that of the PI method.

Combined low voltage ride through and power smoothing control for DFIG/PMSG hybrid wind energy conversion system employing a SMES-based AC-DC unified power quality conditioner

An Interline AC-DC unified power quality conditioner (UPQC) protection device is proposed and designed based on superconducting magnetic energy storage (SMES) in this paper to improve low voltage ride through (LVRT) capacity and smooth output power for doubly fed induction generator (DFIG)/ permanent magnet synchronous generator (PMSG) hybrid wind energy conversion system (WECS). The AC side of the proposed UPQC is connected in series with the terminal of DFIG as a dynamic voltage restorer (DVR), and the DC side of the UPQC is connected in parallel with the DC bus of PMSG for DC bus voltage maintenance and output power adjustment. For a case verification, a 4.76-H/1760-A superconducting coil (SC) is designed as an energy storage device utilized in UPQC to carry out the energy conversion. Finally, the performances of the proposed protection scheme under the conditions of wind speed variation, three-phase-to-ground fault and two-phase-to-ground fault have been presented and analyzed via simulation, to verify the effectiveness of the proposed AC-DC UPQC in DFIG/PMSG hybrid WECS.

A Two-Grid Interline Dynamic Voltage Restorer Based on Two Three-Phase Input Matrix Converters

Energy quality problems can cause diverse failures of sensitive equipment. Dynamic voltage restorers (DVRs) are devices that have been proposed to protect sensitive loads from voltage sag effects. However, the compensation capacity of DVRs is limited by the amount of energy stored in the restorer. One way to overcome this limitation is to use the interline DVR (IDVR) structure in which two or more DVRs connected to different feeders share a common DC-link. This paper proposes a new IDVR topology based on two three-phase input matrix converters (TTI-MC) without a capacitor in the dc-link. The TTI-MC integrates the power from two feeders and synthesizes the dc-link voltage. The inverters take the dc-link voltage and generate the appropriate compensation voltages to keep the load voltages stable. Each one of the inverters has its own modulation algorithm which are synchronized with the TTI-MC control. Inverter control is carried out in the reference frame dq and a modified space vector pulse width modulation (MSV-PWM) technique is used. TTI-MC control is performed in the dq reference frame with proportional-integral controllers and the modulation is based on the carrier-based pulse width modulation (MCB-PWM) technique. The proposed Two Input Interline DVR (TI-IDVR) extends its compensation range and has multifunctional capabilities. The efficiency of the proposed TI-IDVR is corroborated by simulations on MATLAB/Simulink.

A novel intrinsic space vector transformation based solar fed dynamic voltage restorer for power quality improvement in distribution system

Electric power aims to generate electrical energy and distribute to the end-user application at an acceptable voltage level. The quality of power will be affected by various factors like voltage sag, swell, harmonic and Power interruptions, etc. The major reason behind the deteriorations of the power quality is nonlinearity in loads which draws out harmonics. Due to this nonlinearity, all loads cause disturbances in the voltage waveform. In this paper, an Intrinsic Space Vector Transformation (ISVT) based solar fed Dynamic Voltage Restorer (DVR) is connected in series with the power grid to compensate for the reactive power. The operation of the proposed DVR model produces reactive power based on the voltage sag and voltage swell. The ISVT controller produces an appropriate pulse to the voltage source inverter (VSI), which delivers a suitable reactive power to compensate for the sag and swell voltages in the grid. Moreover, solar fed DVR reduces Total Harmonic Distortion (THD) value at the time of voltage sag mitigation. The performance of the proposed system is evaluated by analysing the power consumption and efficiency. Finally, the proposed system is compared with other existing methods. The simulation is carried out using MATLAB SIMULINK 2017b software.

Identification Design for Dynamic Voltage Restorer to Mitigate Voltage Sag Based on the Elliptical Transformation

In this article, a new identification tool for dynamic voltage restorer (DVR) is proposed to achieve flexible active and reactive power dispatches during voltage sags. The presented tool entirely relies on the theoretical analysis of the elliptical transformation, and identification marks are determined for different power injections by using one set of digital codes. Besides, two parameters are presented in the accurate mathematical description of the current references, which guarantees continuous power delivery by selecting the proper values. The chief advantages include the smooth transition state during changes in different power deliveries and the elimination of active and reactive power oscillations. Then, the characteristics of the identification tool corresponding to the different power dispatch are analyzed to reveal the feasibility of the given current references. Finally, experimental tests utilizing a laboratory prototype are used to verify the flexibility of the proposed control schemes.

Investigation of Voltage Sags Effects on ASD and Mitigation Using ESRF Theory-Based DVR

Voltage sag is a frequently occurring power quality disturbance in the industries equipped with adjustable speed drives (ASD). A detailed investigation of voltage sag effects on ASD performance with the novel mathematical analyses to estimate the ASD parameters during different types of voltage sag is discussed in this article. The effects of voltage sags are mitigated using an enhanced synchronous reference frame (ESRF) theory-based dynamic voltage restorer (DVR). The working principle of the ESRF theory-based DVR during sag is also described. The investigation of the effects of type A, type B and type F voltage sags on ASD parameters are verified using the simulation and the experimental studies. Further, these effects are mitigated by the ESRF theory-based DVR using the developed simulation and experimental models. The ESRF controller of DVR is working effectively during voltage sags by improving its transient response, which tightly regulates the DC-link voltage of ASD around its reference value. Also, the steady-state response of DVR is enhanced during severe voltage sag, which further validates the ability of the ESRF theory-based DVR. This type of improved performance of ASD during voltage sags cannot be obtained using other existing SRF theories of the DVR.

Power Quality Enhancement Using Dynamic Voltage Restorer (DVR)-Based Predictive Space Vector Transformation (PSVT) With Proportional Resonant (PR)-Controller

In the power distribution system, the Power Quality (PQ) is disturbed by the voltage sag and swells. The Dynamic Voltage Restorer (DVR) is used to enhance various PQ problems like voltage sag, swells, and Harmonics. The previous Intrinsic Space Vector Transformation (ISVT) control techniques with DVR system, to compensate the power quality issue. It produced a steady-state error, low efficiency, and high THD. The SMES based DVR has provided excellent results in overcoming these issues. The energy is stored by DVR through a storage element, which takes alternate energy from a Solar PV cell. The Maximum Power Point Tracking (MPPT) based P&O algorithm is implemented to equalize the solar power. The Voltage Source Inverter (VSI) generates the reactive power, which has to be compensated with the help of Pulse Width Modulation (PWM) and the feedback control loop are essential to enhance the injection of reactive power to the line. Due to this reason, a proposed Predictive Space Vector Transformation (PSVT) control-based DVR is implemented. It analyzes the variation of power on the distribution side and generates the proper feedback control to the inverter systems. In the instant of voltage injection to the line with the help of DVR, the phase angle mismatch happens which is not synchronized reactive power to the grid. Due to the non-synchronization of reactive power, more harmonic distortion is generated. A Proportional Resonant (PR) controller is introduced, which is Proportional Resonant (PR) current controller. The current injected by the inverter into the grid in phase with the grid voltage maintain constant with unity power factor. The PR controller design is cascaded with a harmonic compensator to mitigate low order odd harmonic components present in the output current of VSI and minimize the total harmonic distortion (THD). The performance of the proposed is evaluated using MATLAB 2017b software.

Power quality enhancement using Artificial Neural Network (ANN) based Dynamic Voltage Restorer (DVR)

The power quality, which can affect consumers and their utility, is a key concern of modern power system. The sensitive equipment is damaged by voltage harmonics, sag and swell. Therefore, as usage of sensitive equipment has been increasing, power quality is essential for reliable and secure operation of the power system in modern times. The potential distribution flexible AC transmission system (D-FACTS) device, a dynamic voltage restorer (DVR), is widely used to address problems with non-standard voltage in the distribution system. It induces voltages to preserve the voltage profile and ensures continuous load voltage. In this paper, the voltage sag and swell is compensated by DVR with an artificial neural network (ANN) controller. For the generation of reference voltage for voltage source converter (VSC) switching, and for the voltage conversion from rotating vectors to stationary frame, synchronous reference frame (SRF) theory is applied. The DVR Control Strategy and its performance is simulated using MATLAB software. It is also shown a detailed comparison of the ANN controller with the conventional Proportional Integral controller (PI), which showed ANN controller’s superior performance with less Total Harmonic Distortion (THD).

Maiden Voltage Control Analysis of Hybrid Power System With Dynamic Voltage Restorer

This work is a maiden attempt towards the voltage stability enhancement of a hybrid power system (HPS) comprising of Parabolic Trough solar power (PSP), Dish-Stirling Solar Power (DSP) and diesel generator (DG). DSP coupled with induction generator requires reactive power for its field winding to be magnetized whereas PSP employing permanent magnet synchronous generator (PMSG) doesn’t require reactive power for excitation. So, it’s worthwhile to infer that PSP reduces the reactive power requirement for its own functionality and may meet the same load demand at low voltage compensation. Lower voltage compensation requirement results in higher voltage stability. Besides, dynamic responses of the system are also improved as the HPS has been incorporated with Voltage Compensating Devices (VCDs) like Static Var Compensator (SVC), Static Synchronous Compensator (STATCOM) and Dynamic Voltage Restorer (DVR). Inclusion of FACTS devices reduces the probability of the transient voltage instability. HPS with FACTS devices under PSP has been subjected to the critical change in load with positive and negative infinite slope at regular interval of time to see the system practicality and its feasibility. The graphical and numerical analysis of the proposed system explicitly shows that the proposed HPS with PSP retains the system voltage stability with great margin under DVR. The efficient hybrid power system as a whole has been achieved to maintain the system reliability in terms of voltage because of the presence of PSP and DVR.

WITHDRAWN: Mitigation of voltage sag/swell by dynamic voltage restorer using fuzzy based particle swarm controller

Reliability of distributed system is measured with the power quality (PQ) that gains more interest of investigators and turned to be huge concern in commercial and industrial purposes. This work examined the voltage sag and swell problem and concentrates on improving the design of dynamic voltage restorer (DVR) for enhancing power quality. Here, a novel Fuzzy based Particle Swarm controller (F-PSC) is anticipated for reference DVR voltage creation. Here, various voltage injections are given for diminishing DVR rating and to enhance performance metrics like output power, size and cost. The anticipated model is provided for PQ sag and swell problem with MATLAB environment. While in compensation, output attained from DVR is compared with other controller model. Simulation outcomes validates that this controller provides economic solution for industrial requirements by offering compensation problems in shorter time duration.

Enhanced LVRT capability of Wind Turbine based on DFIG using Dynamic Voltage Restorer controlled by ADRC-based Feedback control

For grid-connected DFIG-based wind turbine, Fault Ride Through (FRT) or Low Voltage Ride Through (LVRT) capability is vital problem that need to be improved. This paper proposes an Active Disturbance Rejection Control (ADRC) strategy applied to Doubly Fed Induction Generator (DFIG) based Wind turbine (WT), which integrates a Dynamic Voltage Restorer (DVR). The DVR connect in series the DFIG output terminal and the utility grid. The ADRC scheme of the new topology DFIG-based WT with integrated DVR is designed to compensate grid voltage disturbances, which in turn meet LVRT requirement and increase the level of wind power penetration. The performance of this WT-DFIG-DVR structure is investigated in different operating scenarios in order to show the skills of the designed controllers.

Power quality monitoring for a solar PV grid controlled system at non-linear induction drives load

This paper unveils the impact of non-linear induction motor drives on operation of transformer-less single-stage solar photovoltaic (SPV) grid tied inverter system. The system is controlled by an indirect type data-based maximum power point tracking (MPPT) technique. A fuzzy-logic controlled (FLC) dynamic voltage restorer (DVR) is operated coordinating two non-linear induction motor drives load: direct torque flux control (DTFC) and field-oriented control (FOC). Importantly, power quality (PQ) analysis for FOC induction motor drive is validated with DTFC induction motor drive. Results reveal mitigation of unbalanced voltage sag and voltage swell among the SPV converter, load and grid during transient conditions produced by fault. The effectiveness of FLC-DVR at FOC drive load is demonstrated over DTFC drive load and linear load for validation. It is worth mentioning that controlling action of FLC-DVR is implemented effectively at non-linear loads. As illustrated by IEEE-519/1547 standard, a reduction in total harmonic distortion (THD) and DC offset current is reported in grid voltage and current for accuracy. The proposed framework illustrates a comparative PQ study to justify satisfactory performance under varying environmental conditions.

Comparison the Performance of the Dynamic Voltage Restorer Based on PI, Fuzzy Logic, and Fuzzy Neural Controller

The Dynamic Voltage Restorer (DVR) is one of the most efficient and effective custom power devices in protecting the sensitive equipment against voltage sag and voltage harmonics due to; lower cost, smaller size and dynamic response. The inverter is the core of the DVR and it directly affects the performance of the DVR, incorrect injection or delay in the process would be dangerous to sensitive loads. The major functions of the DVR controller are, detection of voltage disturbances events in the system, calculation of the compensating voltage and generation the reference signal for the PWM to trigger the voltage source inverter. PI controller and fuzzy logic controller has been compared with the proposed fuzzy neural optimized fuzzy logic controller in correcting the sag problems and mitigating the harmonics distortion with linear and non-linear loads. Fuzzy Neural optimized Fuzzy Logic controller is the most efficient in improving the performance of the Dynamic Voltage Restorer in compensating any kind of voltage variations and reducing the voltage Total Harmonic Distortion (THD) by enhancing an injection capability of the DVR which is highly influenced by a control algorithm employed. The system is simulated in MATLAB and results confirm the validity and feasibility.

Voltage stability enhancement in grid-connected microgrid using enhanced dynamic voltage restorer (EDVR)

Microgrid (MG) has extensive properties to overcome common problems of local distribution system. Some of those problems are generation and demand difference, blackout and brownout, environmental concerns due to burning of natural resources in power stations (indirectly), and reliability issues. Research on microgrid is being conducted to enhance its features to mitigate power quality (PQ) problems associated with distribution system. Voltage sag and swell have been major power quality problems for decades, loads in distribution system are heavily affected due to these power quality problems. In the distribution system, microgrid and power quality compensation strategy should be existed in order to ensure reliability and voltage sag/swell mitigation. Dynamic voltage restorer (DVR) is comprehensive power electronics based Flexible Alternating Current Transmission System (FACTS) device, it is third-generation FACTS device as its control scheme selection flexibility and power line coupling approach make it advance when compare to first and second-generation FACTS devices. In this paper, an Enhanced Dynamic Voltage Restorer (EDVR) is presented to efficiently mitigate voltage sag/swell in grid connected microgrid. On the one side, the presence of microgrid structure ensures reliability of distribution system for local loads on the other side, EDVR ensures voltage sag/swell free power supply for loads. The control strategy of EDVR is based on enhanced synchronous reference frame (ESRF) approach and fuzzy technique system. ESRF is specially design for fast and precise operation of EDVR whereas; fuzzy technique system is responsible for standardized voltage supply for local loads. DC link voltage of EDVR is effectively regulated with the help of proposed control scheme at the time of voltage sag/swell compensation. Stability analysis of ESRF control has been done using modeling of VSC and eigenvalue analysis system. Simulation results on MATLAB/Simulink verified the performance of EDVR under presented control approach hence the specific loads in distribution system are more secure under proposed microgrid system with EDVR.

Grid-Connected Rectifier Based Dynamic Voltage Restorer To Improve Power Quality By Compensating Voltage Sag And Swell

Voltage sag and voltage swell are frequently occurred power quality problems in present power distribution system, which are cause more problems to avoid these problems and maintain constant voltage at sensitive load during sag and swell Dynamic voltage restorer gives solution .we propose self-supported DVR, to minimize the cost by preventing external dc source in DVR, it is controlled by SRF PI control along with an inner current loop to stabilize the system and outer voltage loop to increase the system robustness. The proposed model provides fast voltage restoration for a short and long duration of voltage sags and swells manage wide load current variation for short and long voltage disturbances. In this paper, we present the effectiveness of the proposed method by using MATLAB/simulation results. A laboratory prototype DVR is modelled and we are using CCS studio to interface DSPTMS320F28027F

Design and implementation of DVR as fault current limiter in DFIG during grid faults

The wind grid code requirements for low voltage ride through of various countries demand the DFIG to remain connected to the grid during the event of occurrence of voltage dip. Dynamic voltage restorer supports the grid and enables the uninterrupted operation of DFIGs during partial voltage sag. The increased depth of voltage sag causes rise in stator current and eventual increases in rotor current and dc link capacitance voltage of DFIG. This paper focuses on an enhanced topology of fault current limiting dynamic voltage restorer for supporting the grid and DFIG during fault currents caused by severe voltage dips. The optimal parameters design of fault current limiting dynamic voltage restorer for DFIG systems are discussed in detail. The novelty of the proposed control strategy of fault current limiting dynamic voltage restorer is justified by comparing its performance with the existing methods of fault current mitigations popular with wind farms such as crowbar protection and dc chopper methods. Analytical results of fault current limiting dynamic voltage restorer with DFIG in time domain prove to have the combined effect of both crowbar protection and dc chopper-controlled rotor protection during severe unbalanced grid faults.

Fuzzy Neural Optimized Fuzzy Logic Controller Based Dynamic Voltage Restorer for Power Quality Improvement with Non-linear Loads

Recently a large attention has been focused on a power quality domain due to: disturbances caused by non-linear loads, Increase in number of electronic devices and growth of renewable energy sources. Power quality measures the fitness of electric power transmitted from generation to industrial, domestic and commercial consumers. At least 50% of power quality problems are of voltage quality type. In power system voltage sags, voltage distortion introduced by harmonics, and asymmetrical voltage are considered to be the most severe affecting power quality, because both utilities and consumers are affected by these disturbances. Different methods introduced to solve power problems but the custom power devices are the most effective and efficient methods, one of which is the use of the Dynamic Voltage Restorer (DVR). The main objectives of this research are to achieve more accuracy in compensating the voltage variations and reducing the total harmonics distortion (THD) to acceptable limits. Most of the researchers applied the control strategies to compensate the voltage disturbances in critical load but did not focus on the objective of reducing the total harmonics distortion (THD). In many sensitive loads such as, airport lighting system, medical equipment, auxiliary plant of power system, and adjustable speed drives., the level of the (THD) is more important, this research focuses on mitigating the harmonics to less than 3%. An adaptive controller like fuzzy neural optimized fuzzy logic controller is proposed to improve the performance of the DVR in injecting the required voltage to restore the load voltage to its nominal value under different voltage variations which are created by MATLAB/SIMULINK program for a period of 0.15s from 0.8s and kept till 0.95s.