To make a secondary distribution system operate at its optimal performance, the use of an advanced power custom power device known as dynamic voltage restorer (DVR) has been proposed and researched. Optimum performance means acceptable voltage profile, increased reliability of supply, no overloading of cables and distribution transformers, the absence of unbalances in both voltage and current phases, and acceptable loss. This study involves the effective mitigation of power quality disturbance in secondary distribution networks as a result of voltage variation and voltage imbalance using a very effective power electronics-based custom power controller known as DVR. A DVR is connected between the secondary distribution transformer and the customer load along a feeder with a radial arrangement. An innovative new design-model of the DVR has been proposed and developed using dq0 controller and the proportional integral controller method. Model simulations were carried out using MATLAB/Simulink in Sim Power System tool box. The simulation results attest to the optimal performance of the proposed DVR configuration in mitigating the power quality problems, correcting voltage unbalance, and enhancing the voltage profile at the customer side to a statutory limit of ±5.

Effectiveness of Dynamic Voltage Restorer for Unbalance Voltage Mitigation and Voltage Profile Improvement in Secondary Distribution System

Design and modeling of SMES based SAPF for pulsed power load demands

This paper presents literature review for improving the power quality by using the unified power quality conditioner (UPQC). There is a more complex network in the power system, in which generating station is connected with the load center through long transmission and distribution line. For improving the performance of distribution network the new concept came into existence known as custom devices. One of the custom power device is unified power quality conditioner is one of the custom power devices. The different configurations of UPQC system for single phase and three phases are well discussed in this paper. The various researchers have given different names to the UPQC according to their function, topology and application. The various topologies of UPQC explained are, left shunt (UPQC-L), right shunt (UPQC-R), open UPQC, Interlined UPQC (UPQC-I), Modular UPQC (UPQC-ML).

Power Quality Improvement by Using UPQC: A Review

An improved control strategy of 3P4W DVR systems under unbalanced and distorted voltage conditions

This paper presents a discrete-time domain control scheme for balanced voltage sag compensation using a Dynamic Voltage Restorer (DVR), which is recognized to be an appropriate and economical power electronic device with which to ameliorate these disturbances. The proposed control method is implemented in the synchronous reference frame (SRF), with two nested regulators, one of which includes an integral action. This algorithm has some advantages with respect to other control algorithms, such as the fact that the proposed methodology permits all the closed-loop poles of the DVR system to be placed in the desired locations in order to define the dynamical behavior with a reduction in the number of the electrical magnitudes to be measured and without the need for state observers, as occurs in traditional control methods. What is more, the well-known inner current loop implemented in other control schemes, which is employed to attenuate the resonance of the plant, is unnecessary. Furthermore, the unbalanced voltage sag compensation can be achieved by adding a “plug-in” controller and following the same methodology presented for balanced voltage sags to design the controller. The good performance of the proposed control scheme is validated by means of simulation and experimental results carried out with a 5 kW DVR laboratory prototype. The discrete-time control method is also compared with two control schemes previously proposed in literature.

/pdf/a-discrete-time-control-method-for-fast-transient-voltage-2i1rxer4w9.pdf

A Discrete-Time Control Method for Fast Transient Voltage-Sag Compensation in DVR

An improved Dynamic Voltage Restorer for power quality improvement

An improvised RLC interface filter for a Dynamic Voltage Restorer (DVR) is proposed. The RLC filter is connected in the front end between the IGBT based Voltage Source Inverter (VSI) and the injection transformer and is able to eliminate voltage harmonics in the system and also switching harmonics generated from VSI. The voltage at the sensitive load end is pure sinusoidal. In this method, the DVR produced Pulse Width Modulation (PWM) voltage with voltage harmonic canceling the voltage harmonic generated from the supply main. The VSI handles harmonic power. The low order switching harmonics generated by the IGBT based VSI is suppressed. The DVR has greater voltage injection capability. Good dynamic and transient results recorded and Total Harmonic Distortion (THD) at the sensitive load end is minimized. The voltage at the sensitive load is sinusoidal and at 1.0 pu. PSCAD/EMTDC is used to validate the performance of the interface filter and the DVR. Simulated results are presented.

https://iopscience.iop.org/article/10.1088/1742-6596/622/1/012058/pdf

Power System Harmonic Elimination to Improve Power Quality

A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented.

https://iopscience.iop.org/article/10.1088/1757-899X/78/1/012010/pdf

Voltage harmonic elimination with RLC based interface smoothing filter

The power quality disturbance in a power distribution network was voltage sag and swell and voltage harmonic. New ideas, methods and techniques had been introduced by researchers to improve the quality of supply particularly at the sensitive load end. Many of these methods have their own drawbacks such as complexity, slow response and sensitivity to parameter variations. In this research, an improved Dynamic Voltage Restorer (DVR) topology has been designed and modeled to be used on a 415 Volts distribution network. A seven level cascaded multilevel inverter using multicarrier SPWM technique controller was proposed to handle the voltage imperfections. An innovative controller based on the Synchronous Rotating Reference Frame (SRRF) to overcome the disadvantages of the existing controller schemes by reducing the complexity, number of signal measurements and computing time has been developed. The controller was able to control the zero sequence voltage during unbalance fault period. The switching frequency of the phase shift SPWM was low and hence, the switching loss was low. The Total Harmonic Distortion (THD) with the proposed DVR was significantly reduced to 1.64 % as compared to other traditional models and was within the IEEE Standards 519-2014. The proposed controller algorithm provides excellent voltage compensation.

K. Chandrasekaran

Papers

An improved Dynamic Voltage Restorer for power quality improvement

Power System Harmonic Elimination to Improve Power Quality

Voltage harmonic elimination with RLC based interface smoothing filter

Design of seven level Dynamic Voltage Restorer for voltage sag and harmonics mitigation