Voltage Sag (original) (raw)
A Device for Improving the Voltage Sag Ride Through Capability of PCs
2010
Voltage sags have emerged as one of the most serious power quality problem. Voltage sag disturbances which sometimes last less than a fraction of second, can cause sensitive equipment such as personal computers (PCs) to shut down and interrupt PC controlled systems and processes for considerable periods of time, which leads to loss of production and high costs. In order to overcome this problem, an electronic device to enhance the ride through capability of PCs during voltage sag is developed. The proposed device can be connected to the power supply unit of PC to add a new operational state to the PC's power supply, in which PC is supplied for one second by a capacitor bank in the events of voltage sags. It consists of sag detection circuit, control circuit, switching circuit and capacitor bank. The device is easy to use and can be built from cheap, commercially available components. Some of the salient features of the proposed device are that it does not require additional uninterruptible power supply for its operation, and it does not draw high levels of inrush currents from the mains. Furthermore, the proposed device can be adapted to other voltage sensitive devices such as lamps and ac contactors. Copyright © 2010 Praise Worthy Prize S.r.l. -All rights reserved.
The paper presents voltage restoration system is class of custom power device providing consistent distribution of power quality. It use series connected custom power apparatus which is aimed to defend sensitive loads from supply side distribution except for outage. Mainly we used UPS stabilizer to reduce voltage and the stabilizer will operate when the voltage is increased. So we designed dynamic voltage restorer that operates both condition like increase and decrease of voltage. So this is advantage and more accurate and also it is less costly then UPS and stabilizer. Due to installation of this system battery life can also be increased because when variation occurs in voltage supply from line will be continued from line and difference of voltage will be taken from battery. For example in UPS if input voltage is 180v, circuit will be trapped and entire load will be on battery that generate 50v AC inject to it with in phase, same way if output is 260v and generate 30v AC and inject it with out of phase signal in this way the output will be fixed at 230v AC this is advantageous and battery life will also increase. Keywords: DVR (Dynamic Voltage Restorer), UPS (Uninterruptible Power Supplies), APF (Active Power Filters), Voltage Source Converters (VSC), PIC Kit, Injection Transformer _______________________________________________________________________________________________________
Elektronika ir Elektrotechnika, 2020
The paper deals with an application of combined techniques of dynamical voltage restorer (DVR) and uninterruptible power supply (UPS) that make possible both the short voltage sags compensation, as well as longer power supply interruptions, under the simultaneous operation of equipment and network. This is enabled mainly by an instantaneous voltage sag detection, quick bidirectional over-switches, and an instantaneous control method of the output voltage. This needs a fast control method, which can provide a voltage recovery for phase-sensitive loads during several calculation steps, so the dead-beat regulator is used. Such a system even compensates for the influence of non-linear loads on the power supply network without a change of a phase and amplitude of the supply voltage. The simulation results in Matlab/Simulink, as well as real experiments and their comparison results, are given in the paper.
Nowadays, Power quality is identified as one of the very serious issues in electric power transmission and distribution, because of its bad impact on electricity suppliers, manufacturers and users. Generally we can define power quality as any power problem manifested in voltage, current or frequency deviations that results in failure or disoperation of customer equipment [1]. Presently, most of the industries use power electronics conversion and switching for manufacturing and processing. Sensitive loads such as digital computers, programmable logic controllers (PLC), consumer electronics and variable frequency motor drives need high quality power supplies. Good quality of electric power is necessary for right functioning of industrial processes as well as protection to the industrial machines and its long usage. The frequently occurring power quality issues are voltage unbalance, voltage sag and swell, transients, flickers and harmonic distortions. Among various power quality problem voltage sag and swell are most significant short duration variation problem. Voltage sag and swell [1] can cause sensitive equipment to fail, shutdown and create a large current unbalance. A Voltage sag is a decrease to between 0.1 and 0.9pu in rms value of voltage at the power frequency for durations from 0.5 cycle to 1 min [2]. Faults on electrical power system like short circuit due to insulation breakdown at heavy load conditions can cause voltage sag. Voltage swell, as compared to sag can be defined an increase to between 1.1 and 1.8pu in rms voltage or current at the power frequency for durations from 0.5 cycle to 1 min [2]. Switching off of large loads, supplying capacitor banks etc. can be considered as the basic causes of voltage swell. Generally, Two types of VSC-based CPDs have been commonly used for compensation of the voltage sags and swells and regulating the load voltage [3]. The first one is a shunt device, which is commonly called D-STATCOM and the second one is a series device, which is commonly called DVR [3]. In this paper, the operation of the DSTATCOM and the DVR used for the load bus voltage control have been considered, when Voltage sag & swell occur in the distribution system across the load bus. In this paper, Synchronous reference frame theory is used for generating reference voltages and Space Vector Pulse Width Modulation technique is used to produce the gate pulses for Voltage source Inverter. A generalized converter Configuration is considered for inverter and it has been proposed for medium-voltage distribution system applications. Simulation studies have been performed to check the results in a three-phase distribution system. 2. Configuration of DVR and D-STATCOM: A). Dynamic Voltage Restorer DVR is a series connected solid state device that injects voltage into the system to maintain the load side voltage as near to 1pu. It is normally installed in a distribution system between the supply and sensitive load feeder as shown in Abstract: Nowadays, the rapid developments in power electronics increases use of critical and nonlinear load in power system, due to this it results in nonstandard voltage, current and frequency and reduce quality of power. This nonstandard power results failure of the load connected to the distribution system. Voltage disturbances challenging the industry are Voltage sag and Swell, among them voltage sags are considered the most significant problem to electronic loads. To solve this type of short duration voltage variation problem, various power electronics controller based custom power devices are used. In this paper utilization of including DVR and D-STATCOM in distribution side for purpose of voltage sag and swell compensation by using PI Controller with SVPWM pulse generation technique is described. Simulation results are presented to assess the performance of each device as a custom power solution. To prove the performance of the proposed method simulation results are considered by MATLAB with its Simulink and Sim Power System toolboxes.
International Journal of Scientific Research in Computer Science, Engineering and Information Technology, 2023
Modern power systems are become increasingly attuned to the utility company's power quality. Power quality issues include voltage sag and swell, harmonics, flicker, interruptions, and disruption of the sinusoidal waveform. These issues mostly affect industrial users with a variety of sensitive devices. These issues could cause them to lose a great deal of money. If the voltage drop is greater than the equipment's sensitivity threshold, the apparatus will break or sustain damage. In order to address this issue among consumers, gadgets like the Uninterruptible Power Supply (UPS), Static Synchronous Compensator (STATCOM), Active Voltage Restorer (AVR), and Dynamic Voltage Restorer (DVR) have been developed. A DVR is the most efficient and productive bespoke power device available. Thus, the goal of this work is to investigate how the DVR functions while voltage swell and sag are being compensated for. A sample of the distribution network will be used to investigate the DVR system. There are two feeders in this network, and each feeder is linked to the balanced load. One of the feeds has experienced a number of problems, including LG, LLG, and LLLG, which have caused voltage to sag and swell. To simulate the system, MATLAB/Simulink is selected as the software. By generating an output voltage with the least amount of distortion and harmonic distortion possible, the SVPWM-based approach can regulate the circuit with greater accuracy and enhance the DVR's reaction. The parameters, various circuit topologies, and the effects of power devices of components are discussed. The result of the simulation was recorded and discussed.
Equipment for Voltage and Reactive Power Control
Chapter 1 explained how voltage support requires reactive power control. In this chapter, we describe in detail the main equipment in power systems that are able to deliver or absorb the reactive power through particular aspects of control as they relate to voltage and reactive power.
Voltage sag correction by dynamic voltage restorer with minimum power injection
IEEE Power Engineering Review, 2001
don, UK, on 4-7 April and Power 2000. It provided an international forum for participants to share knowledge, experience, new ideas, and future trends in the ongoing process of electric utility deregulation and restructuring. The conference focused on power delivery technology for a new market and highlighted technology behind the new market brought about by deregulation and restructuring. It served as a meeting place for people from industry, utilities, and the universities to present their work and presented a full spectrum of the competitive market and engineering technologies in the electricity industry service. The symposium was organized by the City University and was cosponsored by IEEE PES and IEE. Financial sponsors included: The National Grid Company plc, UK; Electricite de France; Mitsubishi Electric Corporation, Japan; London Electricity plc, UK; ABB; and A.M. Best International Ltd. More than 140 papers on utility deregulation and restructuring, together with power technologies, were debated during the technical sessions. Delegates from more than 35 countries attended. The high standard of the papers, presentations, and technical discussions was particularly gratifying. The conference was preceded by a tutorial on "Deregulation, New Electricity Trading Arrangements, System Planning, and New Technologies." During the conference, there was an exhibition of products and services related to the theme of the conference, "Competitive Market and Engineering Technologies in Electric Service for the Next Millennium.
Researchpaper-Dynamic-Voltage-Restorer-and-Its-application-at-LV-MV-Level
Dynamic Voltage Restorer is a power electronic device that can protect sensitive loads from various disturbances in the power supply. This paper presents the study & analysis of DVR and power quality problems, voltage sag & swells with its application at Low Voltage and Medium Voltage level. DVR is always connected in series with the distribution feeder. The basic principle of a DVR is simple, by supplying a voltage of desired magnitude and frequency, the DVR restores the load voltage to a desired pre-sag voltage quantity even when source voltage is not balanced. Implementation of DVR has been proposed at both low voltage level as well as medium voltage level thus giving an opportunity to protect high power sensitive loads from voltage deflections .
2008
The electrical energy is one of the easily used and available forms of energy. For electrical engineering, power quality is a noteworthy topic. At present day, the problem of power quality has become one of the major problems which have to be taken into account for the maintenance of power supply quality. For the power generation companies and customer, the most important issue is the power quality. Today's generation mainly depends on electrical energy for maintaining their life style. Today's equipment like electric motors, computers, machines, etc. cannot be used without electricity. In order to improve the technical performance, quality of supply is demanded by the equipment. The problem of power quality is an occurrence which is actually demonstrated as a nonstandard frequency, voltage or current. Service disruption and failure of electricity can be easily found in sensitive industrial loads, utility distribution networks and detracting commercial which causes great fin...
Sensitivity of Personal Computers to Voltage Sags and Short Interruptions
IEEE Transactions on Power Delivery, 2005
This paper discusses the sensitivity of personal computers (PCs) to voltage sags and short interruptions on the basis of the extensive test results. Existing standards and previously published works are reviewed, and a description of a used testing procedure is presented. The following tests were performed: sensitivity to rectangular voltage sags with ideal and nonideal supply characteristics, and sensitivity to voltage sags caused by the starting of large motors. The results obtained emphasize the importance of clear definition of the malfunction criteria for this equipment.
Performance Evaluation & Operation of DSP Control UPS System
Engineering, 2020
An uninterruptible power supply (UPS) is a power conditioner that provides emergency power to a load when the supply power fails. In on-line UPS, the load is always connected to the inverter through the UPS static switch. Specialized expertise was required for collection, analysis, and dissemination of technical information relating to high quality uninterruptible power systems. Inherent in these responsibilities is the coordination of technical and contractual matters relating to the procurement and installation of uninterruptible power supply (UPS) systems which were required to support these facilities. The proposed circuit incorporates an AC/DC & DC & AC converter, which provided power factor correction and to assure feedback control. In our project when the AC main is available, the rectifier circuit will supply the power to the inverter as well as to the battery and battery will be charged. If the supply power fails suddenly, the battery will supply power to the inverter without any interruption and delay. In the constant current charging technique, a digital charger was designed and controlled through PIC12F675 microcontroller. In the realized system, The PIC16C73B was used as microcontroller. It was used to generate sinusoidal PWM (Pulse Width Modulation) signals that are connected to drive n-channel MOSFETs in inverter to assure feedback control and display units. The power circuit of the proposed UPS system was presented and analyzed. Circuit models were derived and a UPS digital control system using a digital signal processing (DSP) with microcontroller has been developed. The uninterruptible Power Supplies (UPS) are widely used by power supply during interruption of regular power supply due to load shedding, power failure, power fluctuations including telecommunication systems, medical systems, industrial control systems etc.
DSP controlled voltage disturbance generator
Journal of Electrical Systems, 2018
Voltage disturbance generator (VDG) is a kind of device used to generate voltage disturbances that may occur in the network in order to test and evaluate the performance of the power quality devices such as Dynamic Voltage Restorer (DVR) and Uninterruptible Power Supply (UPS). Some of the voltage disturbance generator systems which are available in the literature and commercially available are complex and expensive while the others are simple, inexpensive but less functional. In this paper, a new transformer based, digital signal processor (DSP) controlled VDG is designed which can generate balanced and unbalanced voltage sag/swell and interruption and can adjust the depth, duration and initiation point of disturbances. The proposed system is composed of bidirectional switches, variable transformers and DSP based controller. 3 phase 20 kVA experimental setup is developed to verify the performance of the designed system with linear and non-linear loads. Moreover, the performance of V...
SECTION 05 –DYNAMIC UPS SYSTEM
The Dynamic UPS system performs three essential functions: 1. Cleaning and filtering the utility supply 2. Providing power continuity in the event of a utility failure 3. Generating energy for the entire duration of any utility outage The unique concept and design of Dynamic UPS systems maximizes reliability and provides the project with the highest available uptime. Depending on the capacity of the available fuel resource, the Dynamic UPS can deliver power for an indefinite period of time. Dynamic UPS systems operate automatically and seamlessly to safeguard every conceivable and vulnerable load type:
Voltage sag and mitigation using dynamic voltage restorer (DVR) system
Elektrika, 2006
This paper highlights voltage sag as one of a power quality issue and Dynamic Voltage Restorer (DVR) is using for mitigation of voltage sag. Voltage sag is short reduction voltage from nominal voltage, occurs in a short time which can cause damage and loss of production especially in industrial sector. Voltage sag always related with short circuit events and starting motor which draw very high lagging current. Since voltage sag is creating worse effects, the researchers almost keen to find the solutions for this problem. Nowadays, a lot of devices have been developed to mitigate voltage sag such as Dynamic Voltage Restorer (DVR), Distribution Static Compensator (D-Statcom) and Uninterruptible Power Supply (UPS). In this paper, focus is given only on DVR system which will be simulated by using PSCAD software in order to mitigate voltage sag. Mathematics model for calculation of voltage sag and voltage injection by DVR System also described.
Removal of Voltage Sag using Dynamic Voltage Restorer (DVR)
2015
Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that can cause failure or a miss-operation of equipment. With power quality problem utility distribution networks, industrial loads, sensitive loads etc. are suffered. Power quality problem dealt here is Voltage Sag. To overcome the problem related to power quality, custom power devices are introduced. A number of power quality solutions are provided by custom power devices. At present a wide range of very flexible controllers, which capitalize on newly available power electronics components, are introduce for custom power applications. Power system capability can be increased by the use of Flexible AC Transmission System devices (FACTS) in transmission systems experiencing high power flows. The Dynamic Voltage Restorer (DVR) is the key series compensation devices that open up new opportunities to control the power on transmission systems in order to enhance their utilization, increase p...
The widespread use of power natural philosophy devices has semiconductor diode to a whole modification in electrical load nature, of these variations in load causes disturbances in voltage waveforms. The disturbance includes Voltage sag/ swell, interruption etc. the employment of custom power devices is taken into account to be the foremost economical methodology for restoration of system voltage. Dynamic Voltage refinisher (DVR) will offer the price effective resolution for mitigation of short length voltage disturbances in distribution system. Here during this paper, 3 section Dynamic voltage refinisher supported Neural Network controller with Levenberg-Marquardt Back propagation coaching formula square measure projected for mitigating voltage sag, swell and interruptions. Short length voltage disturbances square measure simulated on a 3 section system and also the comparative results has been conferred victimization MATLAB/SIMULINK.
New control technique applied in dynamic voltage restorer for voltage sag mitigation
2009 4th IEEE Conference on Industrial Electronics and Applications, 2009
The Dynamic Voltage Restorer (DVR) was a power electronics device that was able to compensate voltage sags on critical loads dynamically. The DVR consists of VSC, injection transformers, passive filters and energy storage (lead acid battery). By injecting an appropriate voltage, the DVR restores a voltage waveform and ensures constant load voltage. There were so many types of the control techniques being used in DVR for mitigating voltage sags. The efficiency of the DVR depends on the efficiency of the control technique involved in switching the inverter. Problem statement: Simulation and experimental investigation toward new algorithms development based on SVPWM. Understanding the nature of DVR and performance comparisons between the various controller technologies available. The proposed controller using space vector modulation techniques obtain higher amplitude modulation indexes if compared with conventional SPWM techniques. Moreover, space vector modulation techniques can be easily implemented using digital processors. Space vector PWM can produce about 15% higher output voltage than standard Sinusoidal PWM. Approach: The purpose of this research was to study the implementation of SVPWM in DVR. The proposed control algorithm was investigated through computer simulation by using PSCAD/EMTDC software. Results: From simulation and experimental results showed the effectiveness and efficiency of the proposed controller based on SVPWM in mitigating voltage sags in low voltage distribution systems. It was concluded that its controller also works well both in balance and unbalance conditions of voltages. Conclusion/Recommendations: The simulation and experimental results of a DVR using PSCAD/EMTDC software based on SVPWM technique showed clearly the performance of the DVR in mitigating voltage sags. The DVR operates without any difficulties to inject the appropriate voltage component to correct rapidly any anomaly in the supply voltage to keep the load voltage balanced and constant at the nominal value.
Dynamic Voltage Restorer (DVR) System for Compensation of Voltage Sags, State-of-the-Art Review
The problem of voltage sags and its severe impact on sensitive loads is well known. To solve this problem, The DVR is a modern and important custom power device for compensation voltage sags in power distribution systems. The Dynamic Vo ltage Restorer (DVR) is fast, flexib le and efficient solution to voltage sag problem. The DVR is a series compensator used to mitigate voltage sags and to restore load voltage to its rated value. In this paper, an overview of the DVR, its functions, configurations, components, operating modes, voltage inject ion methods and closed-loop control of the DVR output voltage are reviewed along with the device capabilit ies and limitations.