Hybrid reactive power compensation system for low voltage applications

Abstract

This Master thesis presents a three phase hybrid STATCOM (Static synchronous compensator) that provide reactive power (var) for power factor correction in low voltage distribution system. The system consist of capacitor banks and an inverter, based on a voltage sourced inverter (VSI) configuration, which allows the reactive current injection in leading and lagging to the utility voltage. This system also have master controller that controls the reactive power reference of inverter and switching of power capacitors with capability to reduce capacitors switching events to increase the life of power components. The system used phase lock loop (PLL) to synchronization with grid even with significant voltage harmonics. Vector control method is used to generate direct and quadrature components of the grid voltage in a simple and computationally efficient manner in order to generate a synchronized reference signal for the current control loop. The main goal of this project is to study and implement the control system of a grid-tied inverter with LCL filter and its performance with capacitor switching. The objectives of the project are divided in three parts: theoretical, simulation study and experimental work. The theoretical part discuss the harmonics mitigation, inverter topology and control, filter topology and the performance of overall system. Simulation is performed on Matlab/Simulink platform, for experimental verification a prototype is also developed in the lab to prove the effectiveness of the designed filter, controllers and grid synchronization method. The Opal RT-lab hardware in the loop (HIL) is used for hardware testing, which provides a good solution for analysis of design and laboratory prototype implementation