Compensation of Voltage Sags and Swells Using Dynamic Voltage Restorer Based on Bi-Directional H-Bridge AC/AC Converter

In this paper, the compensation of voltage sags and swells using a dynamic voltage restorer (DVR) based on a bi-directional AC/AC converter is presented for stabilizing single-phase AC line voltage. The H-bridge AC/AC converter with bi-directional switches and without bulk capacitor is adopted as the power topology of the proposed system. The proposed novel topology of DVR is adopted to compensate both voltage sag and swell conditions. Additionally, the power factor is closed to unity because a bulk capacitor is not required. The inner and outer loop control is proposed to improve the response with gain scaling; gain control is adopted to reduce the overshoot. Finally, a 2 kVA prototype has been implemented to verify the performance and accuracy of the control method for the DVR system. The peak efficiency of the system is up to 94%, and it can compensate 50% voltage swells and 25% voltage sags.

New SOGI-FLL Grid Frequency Monitoring with a Finite State Machine Approach for Better Response in the Face of Voltage Sag and Swell Faults

The SOGI-FLL (Second-Order Generalized Integrator–Frequency-Locked Loop) is a well-known and simple adaptive filter that allows for estimating the parameters of grid voltage with a small computational burden. However, the SOGI-FLL has been shown to be especially sensitive to voltage sags and voltage swells, which deeply distort the estimated parameters, especially the frequency. This problem can be alleviated by simply using a saturation block at the Frequency-Locked Loop (FLL) output to limit the impact of distortion on the estimated frequency. Improving upon this straightforward approach, in this paper we propose the use of a finite state machine (FSM) for the definition of the different states of the SOGI-FLL frequency response during a voltage sag or swell fault. The FSM approach allows for applying different gains during the fault, enhancing the SOGI-FLL transient response. The performance of the FSM-based SOGI-FLL is evaluated by using simulation results, which show a better and faster response to these kinds of faults.

A D-STATCOM for Power Quality Improvement Under Different Fault Conditions

D-STATCOM has been used to improve the power quality problems, such as voltage sags, voltage swells for different fault conditions. In order to improve the power factor and reduce the harmonic distortions, LCL passive filter is used along with D-STATCOM. The aim of this paper is to compensate the voltage sag and harmonic distortions by designing the D-STATCOM with LCL passive filter across the distribution system. The simulations were performed by using MATLAB/SIMULINK.

Wind Based Doubly Fed Induction Generator for Effective Rotor Side Converter Control

The presence of voltage swells over the DC connection of the successful rotor side converter of a Doubly Fed Induction Generator (DFIG) is natural because of vulnerability in twist vitality and in addition the variety of rotor precise speed. This can weaken the execution of the consecutive converter associated on the rotor side of the DFIG. Subsequently, the principle goal of this paper is to plan a criticism linearization procedure to dispose of the dc-interface voltage swell and additionally acquire solidarity control factor. In this paper, the dynamic demonstrating of DFIG alongside the viable rotor side converter is performed. The criticism linearization strategy controls the inward elements of the successful rotor side converter by considering the rotor q-pivot current and DC connect voltage. The MATLAB recreation results portray the viability of the voltage control strategy, through the varieties of rotor side channel, DC interface capacitance and vulnerabilities in the DC connect voltage.

Hardware realization of DVR with 27 level multi carrier PWM based MLI

The quality of the electrical power delivered to consumers is heavily affected by the power electronics based controllers, introduced in both domestic and industrial sectors, which in turn results in malfunctioning of equipment or eventual damage. Series compensators, Shunt compensators and series-shunt compensators are some of the strategies applied to address the power quality issues effectively. In this work a series compensating device, viz. 27 level-cascaded multilevel inverter based Dynamic Voltage Restorer (DVR) with multicarrier SPWM technique is proposed to mitigate voltage swells and voltage sags. The PWM technique used in this work is Alternate Phase Opposition PWM (APODPWM), which is one of the vertical arrangement multicarrier sinusoidal pulse width modulation techniques, to control the cascaded H-bridge inverter. The single-phase version of the proposed system is simulated to verify the effectiveness in addressing voltage issues and it is found that the obtained simulation results are satisfactory. The THD is found to be 3.40%, which is well below IEEE standards apart from considerable improvement in response time. The prototype of the proposed model is developed and the pic-microcontroller PIC16F887 is employed to implement the APODPWM. The experimental results obtained from the prototype are compared with the respective simulation results and they match with reasonable accuracy.

Mitigation of Unbalanced Voltage Sags and Swells of Power System in Utility Side by using Sen Transformer

Majority of the industrial electrical loads requires balanced three phase supply but in reality there is unbalanced supply due to single phase loads like railway tracks etc.increasing use of non linear loads in modern power distribution network there are some power quality issues like voltage sags and voltage swells, this distortion of the power supply effect the loads which are connected to power distribution network. In order to improve quality of the power, in this paper a Sen Transformer (ST) technique as been proposed to minimize unbalanced voltage sags and swells. The proposed technique mitigates both voltage sag and swell during balanced and unbalanced operating conditions. The proposed ST consists of a programmable tap controller to compensate ride through faults in power system network. The proposed work as been implemented using MATLAB/SIMULINK software. To validate the proposed work, simulation results are presented.