Enhancing Power Quality using a Dynamic Voltage Restorer (DVR) with PI Controller

Abstract

Nowadays, many people are shifting and adapting to the renewable energy sources like wind and solar which are free of cost and easily available to us. But shifting to the renewable energy sources comes with some problems, and we need to focus on those problems. So the power quality is the main problem in this power system and maintaining it consistently time to time. Some situations like voltage sags, voltage swells, harmonic content and so on has major effect on load side. To overcome this problems custom power devices like Dynamic Voltage Restorer(DVR), Distribution Static Compensator are used in power distribution networks. From this custom devices I picked the Dynamic Voltage Restorer(DVR) for my project. The Dynamic Voltage Restorer has much quality like fast flexible and efficient solutions to the voltage sag and swell problems. The DVR works by injecting the voltage in series and synchronize with the standard voltage ensuring a stable power supply. It continuously monitors the standard voltage and if any deviations occur it quickly injects are decreases the voltage keeping the power supply stable. The important parts of the DVR are voltage source inverter(VSI), boost transformer, filter and DC energy source (Solar energy, Wind energy, Battery).This DVR has an excellent performance in protecting the critical load from voltage sag and swell problems.So that’s why I am going with this custom device. By using this I will compensate the voltage fluctuations and instability in the power distribution networks.

Introduction

Introduction

Modern power systems must provide a stable, uninterrupted sinusoidal voltage. However, nonlinear loads, capacitor switching, motor startups, and faults degrade power quality, leading to voltage sags, swells, and harmonics, which damage sensitive equipment.

Problem Statement

Voltage disturbances (especially sags and swells) severely impact load performance. Custom Power Devices (CPDs) are used for mitigation, with Dynamic Voltage Restorers (DVRs) being the most economical and efficient. However, DVRs face switching losses and harmonic distortions, which need to be minimized using PWM techniques and better control strategies.

Literature Review

• PI Controllers are widely used in DVRs due to their simplicity and effectiveness, but they show slow responses in dynamic conditions.

• Researchers have explored advanced control methods like fuzzy logic, ANN, and optimization algorithms (e.g., GA, PSO) to improve performance.

• PI controllers, despite their limitations, remain popular due to ease of implementation.

DVR Functionality

• DVR connects through an injection transformer and operates in bypass mode under normal conditions.

• On detecting a voltage sag or swell, the DVR injects a series compensating voltage to stabilize the load.

• It can block voltage harmonics and provide voltage balancing using negative or zero-sequence injection.

Control Strategy

• PWM-based VSI (Voltage Source Inverter) generates the required voltage with minimized THD.

• PI controller generates corrective voltages based on deviations from reference values.

• The control uses dq0 transformation with feedback from PLL for synchronized voltage correction.

• The wind energy source supplies the DVR, contributing to sustainability.

Simulation and Results

1. Steady State:

• Voltage remains stable at 1 p.u. (pure sine wave).

2. Three-Line-to-Ground Fault (TLGF):

• Simulated fault from 0.1–0.2s (swell) and 0.3–0.4s (sag).

• Voltage deviates drastically beyond IEEE 1159 standard.

3. With DVR:

• DVR detects the fault, activates, and injects corrective voltage during the disturbance.

• Harmonics are filtered, and sinusoidal output is restored.

• Post-compensation, THD reduced from 23.6% to 1.93%, showing significant improvement.

Key Findings

• DVR using PI control effectively compensates voltage disturbances during faults.

• PWM and dq0 control ensures fast and accurate response.

• Wind energy integration enhances reliability and sustainability.

• DVR ensures voltage stability, reduces harmonic distortion, and protects sensitive loads in dynamic conditions.

Conclusion

In conclusion, the objectives of this project to design DVR for compensating voltage sag and swell caused by TLGF are achieved. The performance of DVR in distribution system against voltage sag and swell has been developed by using MATLAB/Simulink (2024b). Also TLGF is considered in distribution line. The problem of voltage sag and swell has been determined by referred in three cases which is steady state, TLGF case and its mitigation with DVR. The outcome show that all result are obtained successfully based on the three cases.

References

[1] S. C. Devi, P. Shah, S. Devassy and B. Singh, \"Solar PV Array Integrated UPQC for Power Quality Improvement Based on Modified GI,\" 2020 IEEE 9th Power India International Conference (PIICON), Sonepat, India, 2020, pp. 1-6, [2] Comparative Analysis between Dynamic Voltage Restorer and PWM-Switched Auto-transformer in Voltage Sag Mitigation Article in International Journal of Integrated Engineering • December 2023. [3] Shah, P., & Singh, B. (2019). Robust EnKF with improved RCGA-based control for solar energy conversion systems. IEEE Transactions on Industrial Electronics, 66(10), 7728-7740. [4] B.Singh, A. Chandra, K. Al-Haddad, “Power quality: problems and mitigation techniques,” Wiley, London, 2015. [5] H.Fujita and H. Akagi, “The unified power quality conditioner: the integration of series- and shunt-active filters,” IEEE Trans. Pow. Electronics, vol. 13, no. 2, pp. 315-322, March 1998. [6] Teke, L. Saribulut and M. Tumay, “A novel reference signal generation method for power-quality improvement of unified power quality conditioner,” IEEE Trans. Pow. Delivery, vol. 26, no. 4, pp.2205-2214, Oct. 2011. [7] Y. Y. Kolhatkar and S. P. Das, “Experimental investigation of a single-phase UPQC with minimum VA loading,” IEEE Trans.Pow. Delivery, vol. 22, no. 1, pp. 373-380, Jan. 2007. [8] Design of DVR using SVPWM, Fuzzy and PI controller Mrs. Varsha Shikhare, Mrs. Yogini Bhosale P.G. Student, Dept. of Electrical Engineering, RIT collage, Maharashtra, India Professor, Dept. of Electrical Engineering, RIT collage, Maharashtra, India. [9] Mitigation of Voltage Sag Caused by Single Line to Ground Fault in Distribution System by using Dynamic Voltage Restorer in Matlab/Simulink Muhammad Afiq Mohamad Rosli1, Dur Muhammad Soomro1* Faculty of Electrical & Electronic Engineering, Universiti Tun Hussein Onn Malaysia, Parit Raja, Batu Pahat, 86400, MALAYSIA DOI: https://doi.org/10.30880/eeee.2021.02.02.061

Copyright

Copyright © 2025 Bekkam Saiteja, Dr. B. Suresh Kumar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.