Dynamic Voltage Restorer Voltage Research Articles

Research on power quality improvement system based on dynamic voltage restorer

AbstractPower quality is a critical issue in power systems that can affect the performance and reliability of sensitive equipment. The dynamic voltage restorer (DVR) is a widely used technology for improving power quality, but it mainly focuses on mitigating voltage sags and often neglects the issue of harmonic distortion. This paper proposes a DVR voltage compensation strategy based on the discrete Fourier transform (DFT). This strategy utilizes the DFT to analyze the voltage waveform, separating the fundamental and desired harmonic components. With this strategy, the DVR can effectively compensate for voltage sag and achieve selective harmonic compensation, thereby improving the power quality of the power system. Additionally, a method utilizing hardware circuitry and an LED as a timestamp is proposed to dynamically estimate digital siginal processor (DSP) resource occupancy rate in real‐time, ensuring effective compensation while minimizing resource occupancy. A 3 kW DVR experimental prototype was constructed and tested to evaluate the practicality of the proposed strategy. The simulation and experimental results show that the method proposed in this paper successfully realizes the compensation of voltage sag and harmonics in the power system, and improves the stability and reliability of the power system.

Hybrid control mechanism-based DVR for mitigation of voltage sag and swell in solar PV-based IEEE 33 bus system

<p><span lang="EN-US">The power quality issues are raised due to sag/swell, which affects the overall performance of the grid-connected system. This study introduces the hybrid control mechanism based on a dynamic voltage restorer (DVR) to mitigate the sag and swell issues in the solar PV-based IEEE 33 bus system. The hybrid controller improves the dynamic performance and boosts the overall efficiency of the DVR system. The proposed work is also used to address the distribution system's voltage quality issues with minimal energy drawn out from the utility grid and effectively use solar energy. The sag and swell are introduced at the grid side and compensated at the load side by injecting DVR voltage. The proportional-integral (PI) controller followed by the fuzzy logic controller (FLC) is used to create the hybrid control mechanism for DVR. In this work, the solar PV system with DVR system is connected to the 29<sup>th </sup>location in the IEEE 33 bus system for performance realization. The hybrid control mechanism-based DVR provides 1.06% and 1.05% total harmonic distortion (THD) at sag and swell conditions for load voltage. The proposed work meets the IEEE 519 standards in terms of THD calculation. The proposed design compares with existing work and shows better THD reduction for load voltages.</span></p>

Dynamic voltage restorer using sliding mode controller: Experimental studies

The simulation and implementation of a sliding mode control strategy for a single-phase dynamic voltage restorer (DVR) to mitigate load voltage sag swell and harmonics is presented in this work. The control strategy's goal is to compensate for the required voltage by regulating the DVR's voltage via an injection transformer while keeping the load voltage constant. The ability of the DVR to achieve a good performance greatly depends on its control strategy. The controller used in this work is based on SMC theory, which consists of creating a passivation output and a storage function to use as a function of Lyapunov. The proposed control scheme of the DVR is initially evaluated in simulations using MATLAB and validated using a laboratory-scale prototype of the entire system, including a source, the DVR circuit and a load. The control scheme is implemented on a dSPACE 1104 board and the MATLAB real-time toolbox. Both the experimental results have demonstrated the effectiveness the proposed control strategy of DVR in mitigating power qualities issues and therefore enhancing the performance of the network.

Dynamic voltage restorer using sliding mode controller: Experimental studies

The simulation and implementation of a sliding mode control strategy for a single-phase dynamic voltage restorer (DVR) to mitigate load voltage sag swell and harmonics is presented in this work. The control strategy's goal is to compensate for the required voltage by regulating the DVR's voltage via an injection transformer while keeping the load voltage constant. The ability of the DVR to achieve a good performance greatly depends on its control strategy. The controller used in this work is based on SMC theory, which consists of creating a passivation output and a storage function to use as a function of Lyapunov. The proposed control scheme of the DVR is initially evaluated in simulations using MATLAB and validated using a laboratory-scale prototype of the entire system, including a source, the DVR circuit and a load. The control scheme is implemented on a dSPACE 1104 board and the MATLAB real-time toolbox. Both the experimental results have demonstrated the effectiveness the proposed control strategy of DVR in mitigating power qualities issues and therefore enhancing the performance of the network.

Control of transformerless T-type DVR using multiple delayed signal cancellation PLL under unbalanced and distorted grid condition

In the near future, the power system network may experience severe voltage distortions due to association of renewable energy sources (RES), and the large penetration of power electronic based loads into the microgrid. To protect sensitive loads from these distorted and unbalanced grid conditions, the commonly used dynamic voltage restorer (DVR) requires effective control algorithms. The effective control algorithm comprises a controller, and accurate estimation of grid phase angle/frequency, and magnitude, thereby the reference DVR voltage is accurately estimated. The synchronous reference frame based phased locked loop (SRF-PLL) is commonly used for phase angle estimation. However, during unbalanced, distorted, and dc-offset conditions, the performance of SRF-PLL is unsatisfactory. To improve its performance, it is cascaded with prefilters such as dual second order generalized integrator (DSOGI), cascaded delayed signal cancellation (CDSC), and multiple delayed signal cancellation (MDSC). Among these prefilters, MDSC has superior performance under all grid conditions with less delay time and memory requirement. In addition to an effective control algorithm, the DVR system requires high power density converters. The power density of the system is increased using transformerless T-type converter. In this paper, the effectiveness of MDSC-PLL for the transformerless T-type converter based DVR is evaluated in MATLAB/Simulink for various grid conditions such as voltage sag/swell, unbalance voltage sag/swell, harmonics, and dc-offset.

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.

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.

An Efficient Pseudo-Derivative-Feedback-Based Voltage Controller for DVR Under Distorted Grid Conditions

Grid integration of distributed energy resources has become a technical challenge in the distribution network operation due to the intermittent nature of renewable energy sources and their impact on grid voltage stability. Thus, a dynamic voltage restorer (DVR) is installed in the distribution network system to reduce such grid voltage impact on sensitive loads. In this article, a pseudo-derivative-feedback (PDF)-based voltage controller is implemented for the effective operation of DVR under voltage disturbances. Response of DVR primarily depends upon its controller action. This article addresses the issues in conventional P and PI multiloop controller with and without feedforward path then proposes PDF control strategy for DVR. Using the proposed controller, dynamic performance of DVR is improved. The efficacy of the proposed controller is illustrated by a comparative study with conventional P and PI controller using time response and relative stability analysis. Finally, PSCAD simulation studies for a 10 kV medium voltage DVR and experimental results using a low voltage laboratory prototype DVR are presented to prove the robustness of proposed controller for DVR under symmetric and asymmetric voltage sags.

Optimal capacity of energy storage for dynamic voltage restorer under electrical faults scenarios using SOS optimization algorithm: Case of south Algerian’s electrical autonomous grid application

In the last decade, one of the Algeria’s preoccupations is the power quality through its national electrical network such as voltage sags and swells, harmonic currents and voltages. The customers connected to the power distribution network suffer from these perturbations, to solve this problem custom power device is used which is called dynamic voltage restorer. This paper describes DVR principle and voltage restoration which will be connected to the 15KV real autonomous networks in small village of south Algeria. Moreover, optimal energy capacity for the proposed devices based on Meta heuristic methods is presented. The dynamic voltage restorer (DVR) has newly established to protect the industrial facilities from voltage sags and other voltage disturbances. The compensation ability of DVR depends primarily on the maximum voltage injection aptitude and the amount of stored available within the restorer. A detailed procedure to design the optimal system is presented by using SOS algorithm based Advancement compensation (PAC) policy in order to improve the voltage property of the device. The planed approach employs Symbiotic Organism Search technique to search for optimal value of phase advancement angle equivalent to minimum power injection from the energy storage element such as a capacitor or battery and its results have been compared to the conventional DVR techniques. According to the achieved results and detailed analysis, The corresponding values of optimized energy are 13,278W-h, 20.847W-h and optimums phase advanced angles found 131.762°, 115.536° for 17% and 40% voltage sag happened through electrical distribution network. Finally, the proposed method has been compared with other methods available in the literature and is found effective and encouraging.

Interruption Avoidance with Space Vector Modified Pulse Width Modulation for Z-Source Inverter

The AC output voltage is always higher than the input DC voltage in Z-Source Inverter. Z-Source Inverter uses a Impedance network to boost DC input voltage without the use of DC-DC converter, but Z-source capacitors lead to interruptions. However, the higher rate of interruptions is directly proportional to higher instantaneous current rate. In recent years, the Z-Source Inverter is introduced in Dynamic Voltage Restorer to control voltage disturbances in the industrialized services. The biggest disadvantage faced by the Dynamic Voltage Restorer (DVR) system is its inability to mitigate the interruptions. Due to the occurrence of interruptions, the DVR collect the faults in the system but it reduces the peak voltage. In order to improve the peak voltage factor on the single phase ZSI, Dynamic Space Vector Modified Pulse Width Modulation (DSV-MPWM) scheme is proposed in this thesis. Initially, Dynamic Space Vector is developed in Z-Source Inverter and results in interruption free transmission system. The interruption avoidance is achieved with the help of switched capacitor integrator and also the current rate is reduced in DSV-MPWM scheme. Secondly, Modified Pulse Width Modulation in DSV-MPWM controls the Z-Source Inverter by generating higher voltage shoots through states. Finally, Hierarchical Dynamic Service Lookup Address Table works on varying dynamic topological circuit design to produce higher voltage factor. Therefore, DSV-MPWM scheme increases the output voltage factor by avoiding the interruptions in the Dynamic Voltage Restorer (DVR). The interruption avoidance automatically attains fault free transmission circuit. Simulation is conducted on factors such as DVR Voltage Magnitude, Source Output Current Magnitude Rate, and Normalized Capacitor Voltage Gain rate.

Compensation of Voltage Sags with Phase-Jumps through DVR with Minimum VA Rating Using PSO based ANFIS Controller

Dynamic Voltage Restorer (DVR) restores the distribution system load voltage to a nominal balanced sinusoidal voltage, when the source voltage has distortions, sag/swell and unbalances. DVR has to inject a required amount of Volt-Amperes (VA) into the system to maintain a nominal balanced sinusoidal voltage at the load. Keeping the cost effectiveness of DVR, it is desirable to have a minimum VA rating of the DVR, for a given system without compromising compensation capability. In this regard, a methodology has been proposed in this work to minimize VA rating of DVR. The optimal angle at which DVR voltage has to be injected in series to the line impedance so as to have minimum VA loading on DVR as well as the removal of phase jumps in the three-phases is computed by the Particle Swarm Optimization (PSO) technique. The proposed method is able to compensate voltage sags with phase jumps by keeping the DVR voltage and power ratings minimum, effectively. The proposed PSO methodology together with adaptive neuro–fuzzy inference system used to make the DVR work online with minimum VA loading. The proposed method has been validated through detailed simulation studies.

Design and Comparison of High Performance Stationary-Frame Controllers for DVR Implementation

The performance of a dynamic voltage restorer (DVR) is determined solely by its controller. The design of high performance control algorithms for DVR control with improved robustness and desirable steady-state and transient characteristics is therefore an important area of study. In this paper, two voltage controllers are proposed in the stationary frame for DVR voltage regulation. A P+resonant controller is first designed to achieve good positive- and negative-sequence fundamental voltage control with the virtue of having high gains around plusmn50Hz. Stationary-to-synchronous frame transformations carried out in traditional synchronous proportional-integral regulators are no longer required with this method. However, with the purpose of achieving explicit robustness in face of parameter variations, an Hinfin controller is also designed. Detailed design procedure is presented to show how an Hinfin controller with high gains around plusmn50Hz can be synthesized through careful selection of its weighting functions. A thorough discussion and performance comparison of these two controllers in both transient and steady-state conditions are also carried out. Finally, both controllers are extensively tested on a laboratory 10-kV medium voltage level DVR system with various voltage sags and loading conditions