| PhD Viva

Name of the Speaker: Mr. Nafih Muhammad I (EE14D026)
Guide: Prof. Mahesh Kumar
Online meeting link: https://meet.google.com/hhb-qzbb-bfh
Date/Time: 24th June 2024 (Monday), 3:00 PM
Title: Design and Control of Multi-functional DSTATCOM with Battery-supercapacitor Hybrid Energy Storage System

Abstract :

Distribution Static Compensator (DSTATCOM) is mainly used to mitigate current power quality problems. A typical DSTATCOM includes passive filter components, a voltage source converter (VSC), and DC-link capacitors. Proper design of these components is necessary for getting good performances from the DSTATCOM. Hysteresis current control is normally used due to its simplicity in implementation, good dynamic response, and inherent peak current limiting capability. But this control scheme has a variable switching frequency. In a variable switching frequency control scheme, it is challenging to design the VSC parameters without knowing the maximum and minimum switching frequencies. In this research work, a detailed analysis of the switching dynamics of hysteresis current controlled four-leg DSTATCOM is conducted, and the design of various VSC components for compensating unbalanced and nonlinear loads is presented. The results obtained from this analysis can be used in any applications involving hysteresis current-controlled four-leg VSC.

The VSC of DSTATCOM can compensate for the source voltage sag and swell. However, it cannot compensate for the voltage interruption. On the other hand, the VSC of the Uninterruptible Power Supply (UPS) can compensate for the source voltage interruption. However, it cannot compensate for the voltage sag and swell. A combined operation of the DSTATCOM and UPS is needed to overcome these limitations. Conventionally, an energy storage system and two VSCs are required to combine the operation of DSTATCOM and UPS.

A control algorithm that uses a single VSC and a battery-supercapacitor hybrid energy storage system (HESS) to function as DSTATCOM and UPS is proposed in this research work. The VSC and the battery-supercapacitor energy storage system mitigate the sag, swell, and interruption of the source voltages. Under the standard source voltages, this system mitigates the load current harmonics, unbalance, and reactive power. The proposed control algorithm uses a State of Charge (SoC) based scheme to control the battery-supercapacitor HESS. This control scheme protects the battery and supercapacitor from overcharging. Also, it eliminates the ripples in the load angle during voltage sag and swell.