Voltage Sag Compensation Research Articles

Compensation of Sag and Swell Voltage by Using Dynamic Voltage Restorer

There is an introduction to the dynamic voltage restorer in this paper that discusses voltage sags and swell. Also, it is about the compensation of voltage sag and swells. The power quality requirement is one of the most important issues. The power quality problem includes voltage sag, swell, notch, spike, transient, etc. Voltage sags and swells are serious problems requiring immediate attention. In order to compensate for them, there are a number of methods to employ. One of the most effective methods of sag and swell compensation is DVR, which is used in low voltage and medium voltage applications. This paper deals with the compensation of sag and swell voltage. The sag and swell of voltage are compensated by using DVR.. Then the operation of hardware and elements in DVR is explained with their rating dynamic voltage restorer. Keywords - Dynamic Voltage Restorer, Voltage Sag and Swell, Voltage Source Converter, Power Quality.

Power quality improvement in distribution system based on dynamic voltage restorer using PI tuned fuzzy logic controller

Purpose. This article proposes a new control strategy for Dynamic Voltage Restorer (DVR) in utility grid for distribution system. The proposed DVR using PI tuned fuzzy logic scheme is based on replacement of conventional DVR and voltage sag compensation in distribution system network. The novelty of the proposed work consists in presenting an enhanced PI tuned fuzzy logic algorithm to control efficiently the dynamic voltage restorer when voltage sag is suddenly occurred. Methods. The proposed algorithm which provides sophisticated and cost-effective solution for power quality problems. Our strategy is based on tuned fuzzy control of reactive powers and also closed loop for harmonic reduction in distribution system. The proposed control technique strategy is validated using MATLAB / Simulink software to analysis the working performances. Results. The results obtained clearly show that DVR using PI tuned fuzzy logic have good performances (sag compensation, harmonic reduction) compared to conventional DVR. Originality. Compensation of voltage sag/ swell in distribution for reactive power and current harmonic reduction by using DVR based PI tuned fuzzy logic controller. Practical value. The work concerns the comparative study and the application of DVR based on PI tuned fuzzy techniques to achieve a good performance control system of the distribution system. This article presents a comparative study between the conventional DVR control and PI tuned fuzzy DVR control. The strategy based on the use of a PI tuned fuzzy controller algorithm for the control of the continuous voltage sag and harmonic for the distribution network-linear as well as non-linear loads in efficient manner. The study is validated by the simulation results based on MATLAB / Simulink software.

Nonlinear Observation and Control of Series Active Power Filters in the Presence of Voltage Sags

This study addresses the problem of controlling series active power filters for voltage sag compensation. Indeed, we can control this kind of filter to generate a voltage series that compensates the grid voltage sag in order to protect the sensitive loads against this perturbation. This study is aimed at seeking a control strategy that meets the main control objective, which is the compensation of grid voltage sags and this by considering the following technical constraints: (i) the nonlinearity of the system dynamics, (ii) the high dimension of the system model, and (iii) the inaccessibility of some system variables to measurements. To meet the main control objective, we propose a nonlinear controller that is designed based on the system nonlinear model, using the backstepping technique. This controller involves a nonlinear regulator and a grid observer. The former copes with the compensation issue. The observer provides online the grid voltage estimations. In addition to a theoretical analysis of the control system, the performances of the proposed controller are evaluated by simulation using MATLAB/Simulink.

Magnetically Coupled Single-Phase AC-AC Converter With Reduced Number of Passive Components

An AC-AC direct single-phase converter based on an impedance network is presented in this manuscript. It possesses all privileges of similar impedance source AC-AC converters such as buck-boost ability, maintaining or reversing the phase angle and sharing the same ground between input and output voltage. Furthermore, a magnetic coupling is exploited to provide high voltage gain by adjusting its turns ratio along with the duty cycle. A safe commutation strategy is implemented to avoid current and voltage spikes across switches needless to utilize snubber circuits. The presented converter offers continuous input current, and ac to ac conversion is done directly without using dc storage, making it appropriate for dynamic voltage restorer to compensate voltage sags and voltage swells. In addition, LC input and output filters are eliminated thanks to impedance network structure. In this regard, the presented topology offers good features in size and cost by reducing passive components compared to similar structures. Also, the comparative investigation shows that the proposed converter benefits from superior operational ranges among similar well-known topologies for the same conditions. Finally, theoretical analyses and operation modes of the proposed converter are discussed and testified by both simulation and experimental results.

Research on dynamic voltage restorer based on self-coupled proportional–integral controller

Aiming at dynamic voltage restorer (DVR) needs real-time detection of voltage sag and fast compensation. However, the traditional proportional–integral (PI) control of DVR is difficult to take into account the fast following, immunity, and robustness of the system. This paper presents a DVR based on a self-coupled PI (SC-PI) controller. Because it contains a differential to a given voltage signal, it improves the speediness of the system. This control method defines unknown, uncertain dynamic, and external disturbance as a total disturbance d. The disturbance rejection and robustness of the system are enhanced by the cooperative control of output and given deviation through the controller speed factor. Through the cooperative control of the output and the given deviation by the controller speed factor, the immunity and robustness of the system are enhanced, and an adaptive speed factor model is introduced to avoid overshoot and oscillation due to integral saturation in the initial stage of dynamic response. The system’s stability is proved, and the effect of voltage sag compensation is analyzed by simulation. The response time of DVR based on SC-PI is 4 times faster than that of traditional PI, the voltage variation is 2.6923 times lower than that of traditional PI, and the harmonic distortion rate of load side voltage is 8.8333 times lower than that of traditional PI control. The results show that the DVR controlled by SC-PI can simultaneously take into account the fast following, immunity, and robustness of the system, proving the scheme’s feasibility and effectiveness.

Circuit Principle and Design of Superconducting Shunt Resonator for Voltage Sag Mitigation

Voltage sags are the most frequent power quality disturbances for modern industrial users, which can be mitigated by installing voltage sag compensation devices. However, most existing voltage sag compensation devices are high cost. This paper proposes a practical cost-effective device to protect sensitive equipment from voltage sags. The proposed device consists of a capacitor and a superconducting coil in parallel as an LC resonance circuit, and a static switch is used to switch the power supply mode. When voltage sags occur, the sensitive load is directly powered by the device, and the energy stored in the circuit is discharged, then switches when grid voltage recovers. Compared with regular voltage sag compensation devices such as DVR, the device has the advantages of low cost, low complexity, and simple control. Further, the device can mitigate voltage swell. The circuit principle of the device is presented. Besides, the correlations between LC parameters and supporting time are revealed. The feasibility of the device is verified by simulations under both voltage sag and voltage swell.

A DC Voltage Sag Compensator Based on SMES-Battery Hybrid Energy Storage

This paper investigates a new DC voltage sag compensating scheme by using hybrid energy storage (HES) technology involved with one superconducting magnetic energy storage (SMES) unit and one battery energy storage (BES) unit. Two fault simulations of power supply fluctuation and sensitive load fluctuation are carried out to evaluate the dynamic voltage and power smoothing behaviours. The results obtained show that this HES-based DC voltage sag compensator has the ability to suppress the discharging / charging current overshoots for the BES unit and to enlarge the voltage compensating time for the SMES simultaneously.

Voltage sag compensation of radial feeders of distribution system by using interline bridge‐type fault current limiter (IBFCL)

Voltage sag compensation of radial feeders of distribution system by using interline bridge‐type fault current limiter (IBFCL)

Measurement and Compensation of Voltage Sag Employing open-loop Single-Phase Dynamic Voltage Restorer

Measurement and Compensation of Voltage Sag Employing open-loop Single-Phase Dynamic Voltage Restorer

A modified bridge-type nonsuperconducting fault current limiter for distribution network application

The electrical distribution network is undergoing tremendous modifications with the introduction of distributed generation technologies which have led to an increase in fault current levels in the distribution network. Fault current limiters have been developed as a promising technology to limit fault current levels in power systems. Though, quite a number of fault current limiters have been developed; the most common are the superconducting fault current limiters, solid-state fault current limiters, and saturated core fault current limiters. These fault current limiters present potential fault current limiting solutions in power systems. Nevertheless, they encounter various challenges hindering their deployment and commercialization. This research aimed at designing a bridge-type nonsuperconducting fault current limiter with a novel topology for distribution network applications. The proposed bridge-type nonsuperconducting fault current limiter was designed and simulated using PSCAD/EMTDC. Simulation results showed the effectiveness of the proposed design in fault current limiting, voltage sag compensation during fault conditions, and its ability not to affect the load voltage and current during normal conditions as well as in suppressing the source powers during fault conditions. Simulation results also showed very minimal power loss by the fault current limiter during normal conditions.

Comparative Analysis of PI controller, Fuzzy controller and Interval Type-2 Fuzzy based Performance of Dynamic Voltage Restorer for Compensation of Voltage Sag and Swell

In today’s scenario, the power quality issues like voltage sag and swell are major concerns in power systems. On the distribution, side to overcome this issue a custom power device DVR(Dynamic Voltage Restorer) is proven to be a more effective solution that is lower in cost, smaller in size, and offers a faster dynamic response for the protection of sensitive load. DVR is a series compensating device which operates as a voltage booster. The application of DVR is entitled to be a flawless compensating device for the compensation of voltage sag and swell. This paper presents the modeling and simulation using various controller topologies like PI controller based on synchronous reference frame algorithm, fuzzy controller, and interval type 2 fuzzy controller. The results are then verified using a Matlab-Simulink environment.

간단한 듀티비 제어 기법에 의한 quasi Z-소스 동적전압보상기

The quasi Z-source dynamic voltage restorer using the conventional switching scheme was able to obtain only the compensation voltage in the out of phase buck-boost mode for voltage swell compensation of the power source and the in-phase boost mode compensation voltage for more than 50% voltage sag compensation. Since this method cannot compensate for the voltage sag of 1-50%, which mainly occurs in industrial fields, a method of connecting additional quasi Z source converter in series and parallel was studied. In this study, a simple duty ratio scheme was proposed which is can be operated as an out of phase buck boost mode to compensate for swell, an in-phase boost mode to compensate for sag of 50% or more and an in-phase buck mode to compensate for sag of 1-50%. In order to prove the validity of this study, PSIM simulation and DSP based experiment were performed. As a result, by the proposed duty ratio control scheme, it was possible to compensate both the in-phase buck boost mode and the out of phase buck boost mode for sag and swell with a single quasi Z-source dynamic voltage compensator. Finally, for each load of 50Ω and 100Ω even if the voltage sag and swell were generated step by step by 10%, the voltage compensation rate remained almost 1, and the THD of the voltage was all good at 5% or less.

Compensating Voltage Sagin Single Phase and Three Phase Lines Using FCL

Voltage sag compensation is provided on both sides of the Point of Common Coupling (PCC) by using FACTS Devices (STATCOM, APF, DSTATCOM, DVR, UPFC) and FCL. The FACTS dev ices provide compensation on input side and FCL provides compensation on output side. A sensitive load is considered at output side of PCC. This paper presents a component called Fault Current Limiter (FCL) in three phase lines. The main objective of the designed component is to protect the sensitive load from the shunt faults. The compensation is being provided at output side of PCC. Load voltage reduces upon the occurrence of shunt fault. The planned structure prevents voltage sag and counter balance the phase-angle of the PCC once fault prevalence. As a result, different feeders which are interlinked to the sub-station PCC can have attentive power quality. During this paper a high performance 3-phase fault current electrical model is planned. The analysis and design is carried out in MATLAB with SIMULINK.

Modeling and Control of a Multiport Converter based EV Charging Station with PV and Battery

As an environmental friendly vehicle, the increasing number of electrical vehicles (EVs) leads to a pressing need of widely distributed charging stations, especially due to the limited on-board battery capacity. However, fast charging stations, especially super-fast charging stations may stress power grid with potential overload at peaking time, sudden power gap and voltage sag. This project discusses the implementation and modeling of space vector modulation to multiport converter based EV charging station integrated with PV power generation, and battery energy storage system. In this paper, the control scheme and combination of PV power generation, EV charging station, and battery energy storage (BES) provides improved stabilization including power gap balancing, peak shaving and valley filling, and voltage sag compensation. As a result, the influence on power grid is reduced due to the matching between daily charging demand and adequate daytime PV generation. Simulation results are presented to confirm the benefits at different modes of this proposed multiport EV charging circuits with the PV-BES configuration with SVM technique. Furthermore, SiC devices are employed to the EV charging station to further improve the efficiency.

Highest Voltage Sag and Swell Compensation using Single Phase Matrix Converter with Four Controlled Switches

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

Mitigation of voltage sag for DVR to comply with voltage security protocol via elliptical trajectory compensation

In this paper, a flexible power dispatch strategy based on the elliptical trajectory is proposed to maximize the operating region for dynamic voltage restorer (DVR) during voltage sags. This control scheme introduces two individual parameters to accomplish continuous power delivery within the voltage security boundaries required by the loads. These two key parameters are presented in the exact mathematical equations of instantaneous power dispatch, which allows the individual control of active power and reactive power of DVR. Under the provisions of the given control strategy, the load voltage regulation and flexible power dispatch are combined together by the voltage sag compensation of the elliptical trajectory. Thus, the voltage source converters output current can be limited within the maximum rated value. A smooth transition can be achieved as well during changes in the operation scheme when fulfilling the presented power delivery. Eight scenarios of different active and reactive power delivery are presented to validate the feasibility of the proposed strategy. Finally, laboratory results are used to reveal the effectiveness of the given control schemes.

High Frequency Solid State Transformer Design Considerations for Power Systems Applications

The conventional power frequency (50 or 60 Hz) transformers are economical, highly reliable and quite efficient but they suffer with certain drawbacks like sensitive to harmonics, voltage drop under load, no protection from system disruptions and overloads, poor performance under dc offset load unbalances and no scope to improve power factor. These transformers with copper wound wires on iron cores are unable to respond to control signals as power generations become distributed and intermittent. So, the need of electronic based regulated power supply with software based remote intelligence has become essential. Also, to easily connect the new energy sources to the grid and to improve the power quality by harmonic filtering, voltage sag correction and highly dynamic control of the power flow, a new type of transformer based on power electronics, known as SST has been introduced. The SST realizes voltage transformation, galvanic isolation, power quality improvements such as instantaneous voltage regulation, voltage sag compensation and power factor correction. It is a collection of high-powered semiconductor components, high frequency power transformer and control circuitry which is used to provide a high level of flexible control to power distribution networks. The SST is a high frequency switched Power Electronic Devices (PEDs) based transformer with high controllability that enables flexible connectivity between existing medium voltage power distribution network, low voltage AC residential system and envisioned DC residential system. In this paper a systematic constructional detail of a SST with a power rating of 2 kVA, operating frequency of 20 kHz and voltage rating of 600/60 V as a scaled-down prototype used for power converter topologies is presented. The design is simple and it avoids the difficulty of choosing massive amounts of empirical parameters.

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

Performance Improvement of a Distributed Generation System Using Unified Power Quality Conditioner

This paper deals with performance improvement of a distributed generation (DG) system using unified power quality conditioner (UPQC). Despite of the several benefits of DG like excellent energy supply, reducing expansion of power distribution system, environmental friendly and so on, there are several challenges existing due to the integration of DG with the grid or operating it in standalone mode. Power quality (PQ) issue is one of the main technical challenges in DG power system. Moreover, harmonic and voltage sag compensation in a DG networks has significantly reduced PQ, which affects the stability of the system. Hence, in this paper, impact of PQ issues in an adopted standalone DG system (comprising of solar, wind and fuel cell based renewable energy sources) is investigated in the presence of UPQC. The realization of UPQC is carried out using conventional synchronous reference frame (SRF) and modified SRF (MSRF) techniques for reference current generation with pulse width modulation voltage source inverter technique for generation of pulses for the inverter along with a PI controller for regulation of DC-link capacitor voltage. The voltage sag compensation with current and voltage harmonics are estimated at different source (ideal and non-ideal) conditions with different control scheme like SRF and MSRF technique. The simulation model of conventional SRF and MSRF technique based UPQC is developed under MATLAB/SIMULINKR environment. The result obtained validates the superiority of proposed technique over others in terms of harmonics elimination and sag compensation.

Autonomous group particle swarm optimisation tuned dynamic voltage restorers for improved fault-ride-through capability of DFIGs in wind energy conversion system

In this paper, a multi-objective tuning algorithm is proposed for the voltage/current controllers of the dynamic voltage restorer (DVR) in an optimal manner in order to improve the fault-ride-through (FRT) capability of the grid-connected doubly-fed induction generators. An active crowbar protection (ACB_P) coupled with the rotor of the DFIG, provides a very little compensation, on blocking the high rotor current during fault condition. Control of DVR is achieved through use of multiple PI controllers. This paper presents a novel multi-objective tuning known as Autonomous Group Particle Swarm Optimisation (AGPSO) to optimally tune the PI controllers. The optimisation algorithm uses diverse autonomous groups confined within a common target to achieve more directed and randomised search results for any population. Voltage sag compensation, total harmonic distortion (THD), RMS value of signal are the three major indices for comparison study during fault. Finally, the performance improvement in FRT of the DFIG with optimised controller was studied through DFIG responses on comparing with normal controller. Efficacy of the proposed controller proposed is verified by a simulation model of DFIG System with 1.5 MW rating in MATLAB. The results are analysed and comparative data are placed to ensure the enhanced FRT capability of the system.