Development of small scale DC microgrid testbed for power sharing

Abstract

One of the most important issues in microgrid control is power sharing. Proper power sharing ensures each power modules in microgrid to output according to their rated power. This paper focus on developing a control method to solve the power sharing problems in DC microgrid. The control method applied in this project is a modified droop control with adaptive virtual impedance. This DC microgrid testbed project involves hardware circuit design, theoretical controller design and controller implementation on the Arduino UNO microcontroller using C language. The project uses Arduino as the main controller to perform the two main objectives of this DC microgrid testbed project, grid voltage regulation and power sharing among the power modules. The functions and features of Arduino are studied independently. In general, Arduino UNO controller is chosen because of following advantages: inexpensive, versatile and robustness. The main testbed circuit design is based on the DC-DC buck converter. The controlling techniques of the project is based on a novel droop control with an adaptive droop impedance control parameter. The conventional droop control in paralleling power modules suffer from some salient disadvantages of poor power sharing and trade off in voltage regulation. With an innovative concept of power sharing index (PSI) which utilizes a cooperative control processing network, an adaptive virtual impedance is updated to generate a set point voltage correction term. As a result, local set point voltage is continuously updated to match up with power sharing condition. The proper power sharing among paralleling power converters according to their nominal ratings is achieved.