Điều khiển hệ thống pin mặt trời kết nối lưới sử dụng bộ biến đổi flyback đan xen

Phong Tien Le et al Journal of SCIENCE and TECHNOLOGY 127(13): 37 - 42

37

CONTROL OF GRID-CONNECTED SOLAR POWER SYSTEMS WITH

INTERLEAVED FLYBACK CONVERTERS

Phong Tien Le*

, Huong Thi Mai Nguyen, Hung Tien Nguyen

University of Technology – TNU

ABSTRACT

This paper proposes a control system connecting for the grid-connected PV (Photovoltaic) system.

The control structure includes two alternating flyback converters, a control unit for connecting PV

system to the grid, filter circuits at input and output of the converters. The output voltages of two

flyback converters having half sinusoidal wave are is converted to completely sinusoidal wave by

unfolding converter with the grid synchronization. This control system monitors the load demand

and generated power capacity of PV in order to regulate power getting from the grid. The

simulation is carried out bay MATLAB/Simulink.

Keywords: Photovoltaic panel, flyback converter, connecting grid, inverter, regulate power.

INTRODUCTION *

Electric power from PV is only generated in

daylight time having irradiance and stored in

batteries to adapt to the load or generated

directly to grid by electronic power converters

[1-3].

Converters are widely used in many fields

that convert DC to AC using electronic power

components such as IGBT or MOSFET. With

the development of digital microprocessors,

more and more converters have high quality,

simple structure and low cost [1-4].

There are two different kinds of inverters. The

first kind is voltage source inverter and the

second kind is current source inverter in

which the output current is AC with fixed

power factor. For the control of a grid￾connected PV power system, we consider a

PV panel with a maximum power point

tracker (MPPT) to have voltage operating at

fixed value.

A design of a PV power system is presented

in detail in [5]. However, this report was not

completed since it still has some missing

parts. Hence, this paper is a complementary

for [5], in which we will present the whole

controlled system with unfolding converter

and the intergration of a simulated MPPT

block.

*

Tel: 0986938968; Email: [email protected]

INTERLEAVED FLYBACK CONVERTER

The DC/DC flyback converter type is the

simplest one since it has only one switch, one

transformer and no inductor at the output.

Another type of the flyback converter is

alternating flyback converters that operate in

discontinuous mode with two flyback

converters as shown in Fig. 1.

Figure 1. Interleaved flyback converter

The principle operation of this converter is

following [6]:

- Step 1 (t0t1): The main switch Q1 is

allowed to conduct and Q2 is non-conducted.

The current ipv1 at the primary side of T1

flows from source to Q1 and backs to source.

Energy is stored in main transformer T1. At

the same time, the energy from capacitor C0 is

supplied to load (Fig. 2).