Design of ultra-capacitor based DVR for power quality improvement

Power Quality (PQ) is the most significant perspectives at transmission and distribution levels. The supply of high grade electrical services required to the customers illustrates this concept. The voltage sag and swell are the most frequent PQ problems that mainly occur in the distribution systems since it may cause equipment tripping, failure of drive systems, shutdown for domestic and industrial equipment. The Dynamic Voltage Restorer (DVR)connected in series has magnificent dynamic capabilities and is a flexible solution for PQ problems. Ultra-capacitors (UCAP)have ideal characteristics such as high power and low energy density essential for the mitigation of voltage sag and swell. This paper presents an enhanced DVR topology capable of delivering deep, extended mitigation for power quality problems. In the proposed DVR, UCAP is used as energy storage as it provides excessive power in a short interval of time. The DVR is integrated into Ultra-capacitor via bidirectional DC-DC converter which supports in presenting a rigid dc-link voltage, and also helps in compensating temporary voltage sag and voltage swell. PI Controller is used in DVR for power quality enhancement. The simulation model for the proposed system has been developed in MATLAB and the performance over conventional DVR is validated with the results obtained.