Mitigation of Voltage Dip and Voltage Flickering by Multilevel D-STATCOM

The basic power quality problems in the distribution network are voltage sag (dip), voltage flickering, and the service interruptions. STATCOM is a Flexible AC Transmission Systems (FACTS) technology device which can independently control the flow of reactive power. This paper presents the simulation and analysis of a STATCOM for voltage dip and voltage flickering mitigation. Simulations are carried out in MATLAB/Simulink to validate the performance of the STATCOM. A comparison between the six-pulse inverter and the five-level diode-clamped inverter is carried out for the performance of 66/11？KV distribution system. 1. Introduction STATCOM has got a much more widely application due to the advent of the concepts of the smart grid and the microgrid and the rapid development of new energy and the distributed generation. The Distributed Static Compensator (D-STATCOM) becomes the tendency of the reactive power compensation and the power quality control in distributing networks at the present time. It is of great significance to enhance the power quality and keep the relay protection devices working normally as it can make a comprehensive compensation to voltage fluctuation, voltage flicker, and three-phase unbalance. The output harmonic in D-STATCOM comes to our attention, as it is a member of the power electronic devices. The relationship between power quality and distribution system has been a subject of interest for several years. The application of a high-voltage multilevel inverter in a 13.8？kV distribution system Static Synchronous (SSC) is examined in [1]. The capability of the multi-level inverter to limit device voltage stress makes it suitable for high-voltage power conversion. A capacitor voltage balancing controller maintains operation of the multi-level inverter SSC under conditions of phase voltage imbalance shown in EMTP simulations. The concept of power quality describes the quality of the supplier voltage in relation to the transient breaks, falling voltage, harmonics, and voltage flicker. Utility distribution networks, sensitive industrial loads, and critical commercial operations suffer from various types of power quality problems like voltage sag, voltage flickering, service interruptions, and harmonics. The various characteristics of voltage sags experienced by customers within industrial distribution systems are described in [2]. The influence of the induction motor load on the characterization of voltage sags is discussed. It came to know that during a fault, an induction motor operates as a generator for a short period of time and