جستجوی مقالات مرتبط با کلیدواژه "dynamic voltage restorer" در نشریات گروه "برق"

The Power Quality (PQ) issue refers to the occurrence of irregular voltage, current, or frequency that leads to failure or incorrect functioning of equipment used by end users. The PQ meter is utilized to monitor a diverse range of power supply characteristics, all of which possess the capacity to impact the effectiveness of both operational procedures and machinery. The dynamic voltage restorer (DVR) performs the role of a specialized power device employed to mitigate the voltage drop experienced at the terminal of a sensitive load. DVR can be controlled by various control designs. This work conducts a comparative analysis on a normally managed voltage system and a medium-power DVR controlled by a neural network (NN), fuzzy logic (FL), or adaptive neuro-fuzzy inference system (ANFIS) by utilizing an output voltage regulator. The identification and rapid compensation of voltage perturbations, such as voltage sag, are essential elements in monitoring and controlling DVRs. The conventional PI controller is commonly employed in regulating DVRs. While the traditional controller possesses certain merits, it is not free of limitations. One such downside pertains to its utilization of constant gains, which can impede its capability to provide optimal control performance in instances where system parameters undergo fluctuations. Possible solutions have been proposed to effectively tackle this issue, such as the use of NNs, FL, or ANFIS controllers. Furthermore, to attain both rapid dynamic response and robustness, a modified d-q converted three-phase voltage regulator was adopted. Instead of employing a conventional three-phase regulator, this particular regulator is operated by means of an NN, FL, ANFIS, or PI controller. The suggested voltage regulator offers a prompt solution for rectifying voltage irregularities, such as voltage sag, by promptly restoring the voltage to the nominal magnitude. The primary source of power adopted in this study is a wind turbine unit.

Applying distributed energy resources (DERs) to power systems has been promoted as a promising option to meet the growing electricity demand. Despite significant economic, environmental, and resiliency benefits, integrating DER, including power electronic devices, into the existing power networks causes stability and power quality issues. Therefore, to meet stability and power quality standard limits, a sort of compensation using cost-effective and energy-efficient technologies and power electronics-based concepts is needed. This paper presents a novel configuration of compensating type custom power devices (CPDs) and fault current limiters (FCLs) for limiting balanced and unbalanced faults and improving the transient performance of distributed generation (DG) sources in a hybrid power system. Moreover, three power grid operational scenarios are addressed to reflect the impact of the type of fault and variable power generation capacity of DGs on transient stability. Four configurations are implemented using two FCLs (BFCL and SFCL) and two energy compensation devices (DVR and UPQC). The transient performance of involved DGs with and without applying proposed compensation methods is simulated. Simulation experiments were carried out using MATLAB/SIMULINK software. The simulation results indicate that UPQC- BFCL is the best solution in all scenarios that improve the transient stability of the proposed power system under both balanced and unbalanced faults.

Due to the increased sensitive loads, improving power quality in distribution grids by custom power tools is one of the important fields of electrical engineering. This paper proposes a new kind of three-phase three-wire dynamic voltage restorer (without including storage sources or DC link) and also its control method.

The proposed structure includes an AC/AC converter, low-pass filters at the input and output sides, and three-phase injection transformers. The control system is based on the combination of feedback and feedforward control that its advantages are high speed, good response quality, and very simple implementation. To overcome the harmonics raised from AC/AC converter switching on the main line, a SOGI-PLL has been used. Also, SOGI-PLL operates independently on each phase so that the asymmetric voltage variations can be identified.

The proposed control method is capable to compensate the power quality problems such as voltage sag, swell, and harmonics in balanced and unbalanced conditions. The detailed modelling and design of the proposed controller are verified through computer simulations and experimental results under different operating conditions. Simulation and experimental results show that the proposed control strategy can compensate the power quality events as close as possible to the desired values under different operation modes.

In this paper, a three-phase three-wire dynamic voltage restorer (DVR) was assessed using direct AC/AC converters without a supply source and DC link. A control system based on combined feedback and feedforward control (CFBFFC) and SOGI-PLL has been proposed for the DVR. The simulation results on a three-phase 20kV system as well as the experimental results obtained from a single-phase 220V system verified the performance of the DVR and the control system. It was shown that this structure can compensate for 0.5pu voltage sag, above 1pu voltage swell, and all kinds of harmonic faults.

Sensitive loads cannot tolerate voltage sags and swells in power distribution networks and lots of problems are engendered for them. Therefore, dif f e rent instruments are pla nn ed to compensate volt a ge swells and sags. Between them dynamic voltage restorer (DVR) has found special import a n c e, because it operates better than others for this purpose and restores voltage to its initial value conveniently. A DVR is a power-electronic controller that can protect sensitive loads from disturbances in the supply system. The DVR is installed in series to the network. In this paper 9 level cascaded inverters with cas ca d ed transfor m e r s are used in DVR internal circuit, but the difference in magnetic flux in cascading transformers has adverse effects on the plan. Therefore, a new switching pattern is used.

In this paper a new topology for Dynamic Voltage Restorer (DVR) with high frequency link is proposed. This topology is able to compensate different types of voltage disturbances such as voltage sag, voltage swell and voltage harmonics. According to the obtained equations, this topology operates as a controllable current source to charge the series capacitor. Due to using High Frequency Transformer (HFT), the volume and the weight of the proposed DVR is decreased in comparison with conventional DVRs. This topology contains two ac/ac converters which are using in the input and output of the device. The absence of DC link capacitors and storage elements is the other advantage of using the proposed structure. In order to verify the claimed features, the proposed topology has been simulated by PSCAD/EMTDC software and examined under several disturbance conditions. In addition, an experimental prototype has been designed and tested. The results of the simulation and experimental cases are presented.

In this paper, a new dynamic voltage restorer (DVR) based on a Trinary Hybrid Multilevel Inverter (THMI) is proposed, which is capable of compensating for voltage sag, swell and flickers for sensitive loads. A Trinary Hybrid nine-level inverter is composed of a smaller number of IGBTs and circuitry compared to similar structures. The base structure of this inverter is based on the connection of the H bridges and consists of two inverters of a single-phase bridge with a different DC voltage, each of which has a voltage of HB three times the previous HB. The inverter is also able to produce a number of higher output voltage levels and less harmonic distortion than cascade topologies, floating capacitors and diodes. This feature enables the structure to be used to compensate for the power quality of power distribution networks. Nearest Level Control (NLC) in the inverter is used to create the desired waveform. The In-Phase control method is selected to control the proposed DVR and use the synchronous reference frame (SRF) method to detect the network voltage fluctuations. To verify and validate the proposed DVR performance, simulations are carried out in the MATLAB / SIMULINK software environment, and the results indicate the optimal performance and desirability of the proposed DVR to compensate for the voltage sag, swell and flicker power distribution grids

This paper discusses the Dynamic voltage restorer (DVR) operation and control for Voltage sags compensation. DVR is a series connected power electronic based device that can quickly mitigate the voltage sags in the system and restore the load voltage to the pre-fault value. Voltage sag associated with faults in transmission and distribution systems, energizing of transformers, and starting of large induction motor are considered as most important power quality disturbances (PQD). The most of the industries uses the power electronics conversion and switching for manufacturing and processing. These technologies are needs high quality and reliable power supply. Not only the industries, but also the electric power utilities and customers are becoming increasingly anxious about the electric power quality. Sensitive loads such as digital computers, programmable logic controllers (PLC), consumer electronics and variable frequency motor drives need high quality power supplies. DVR is recognized to be the best effective solution to overcome this problem. The primary advantage of the DVR is keeping the users always on-line with high quality constant voltage maintaining the continuity of production. Also, this paper simulates the DVR with the power system using MATLAB/Simulink are demonstrated to prove the usefulness of this DVR to enhance the power system quality.

In this paper a new control strategy for dynamic voltage restorer (DVR) is presented to compensate effectively voltage sags. In this strategy, load and supply voltage magnitude and angle are estimated by least error square in short time. Advantage of this method is reducing noise, distortion and harmonic on estimation parameters. Accordingly, these parameters are controlled for each phase separately. Also, it should be noted that due to angle estimation by LES filters, control system does not require phase-locked Loop and this issue causes increase in speed of control system response. In addition, a P䗫⢝ꧭ and Posicast controller are used to eliminate the steady-state error and improve transient response in DVR, respectively. The proposed control system is simulated, using PSCAD/EMTDC software by induction motors starting is connected to 13 bus IEEE standard network. Finally, the simulation results prove that the proposed control scheme performs satisfactorily under sudden changes of load.

In this paper, a combination of simulated annealing (SA) and intelligent water drops (IWD) algorithm is used to solve the nonlinear/complex problem of simultaneous reconfiguration with optimal allocation (size and location) of wind turbine (WT) as a distributed generation (DG) and dynamic voltage restorer (DVR) as a distributed flexible AC transmission systems (DFACT) unit in a distribution system. The objectives of this research are to minimize active power loss, minimize operational cost, improve voltage stability, and increase the load balancing of the system. For evaluation purposes, the proposed algorithm is evaluated using the Tai-Power 11.4-kV real distribution network. The impacts of the optimal placement of the WT, DVR, and WT with DVR units are separately evaluated. The results are compared in terms of statistical indicators. By comparing all the testing scenarios, it is observed that the multi-objective optimization evolutionary algorithm is more beneficial than its single-objective optimization counterpart. Also, the obtained results show that the proposed SAIWD method outperforms the IWD method and other intelligent search algorithms such as genetic algorithm or particle swarm optimization.