DESIGN ANALYSIS AND SIMULATION OF GRID TIE SOL

AR MICROINVERTER

WHY THIS PROJECT ?

IMPORTANCE OF ENERGY HARVESTING • Energy harvesting (also known as  energy

scavenging) is the process by which energy  is derived from

external sources captured, and stored and used to power up

household devices, small scale industrial equipments

and so on.

The different sources can be

Solar power, Thermal energy, Wind energy, Energy from piezoelectric materials .Biomass

SOLAR ENERGY HARVESTING.

In a typical solar energy-harvesting system, multiple

solar panels are connected in parallel to a single

inverter that converts the variable DC output of

multiple PV cells into a clean sinusoidal 50-Hz voltage

source.

DRAWBACKS OF STRING INVERTER/CENTRAL INVERTER

• The performance of the entire solar PV system is dictated by the performance of the weakest solar

panel. Therefore, power production is negatively

affected by non uniformity of solar panels, sunlight variations or

partial shading due to clouds, trees, dust on the panel.

High-voltage DC such as 600V is distributed in the system and has the potential to trigger a high intensity arc which can cause fire. This is a major issue for installing a central inverter based solar power system on the roof of a commercial building.

So Central inverters are not safe for the residential application.

A relatively new option for optimizing solar system

efficiency and reliability is use of micro-inverters that

connect to each individual solar panel. Equipping each

panel with its own micro-inverter allows the system to

accommodate its changing load and atmospheric

condition, which provides optimal conversion efficiency for both the individual panels and

the entire system.

INTRODUCTION

MICROINVERTER Micro Inverters are compact units built with

efficient technology that convert direct current (DC) to alternating current (AC) immediately at the

solar module.

HOW IT WORKS………

1.6 REQUIREMENTS OF SOLAR MICROINVERTER

1. High step up DC- DC converter with less amount of output ripple.

2. Isolation between the PV panel and Output of the

converter.

3. Sinusoidal inverter to convert DC Voltage to sinusoidal Voltage of very less THD and satisfying all grid tie requirements.

4.Output filter to remove harmonics.

SERIES CONNECTED FORWARD FLYBACK CONVERTER

The First stage of SMI is boosting the panel voltage to a high value. For this purpose Series connected forward flyback converter is used.

The SFFB converter has following advantages that makes it a suitable one for SMI

High step up ratio.Low output ripple voltage and current.Galvanic isolation. Simple in design and Only one switch at the input. control becomes

easier

SERIES CONNECTED FORWARD FLYBACK CONVERTER

SINGLE PHASE PV MICROINVERTER

In single phase PV Microinverter the SFFB converter is coupled with single phase PWM inverter. Control loop is employed for the inverter switching to get almost pure sinusoidal wave with THD to satisfy grid interface requirement.

This microinverter can be used both for single phase grid interface and stand alone PV systems.

SINGLE PHASE PV MICROINVERTER

THREE PHASE SOLAR MICROINVERTER

If the high stepped up voltage from PV panel is connected to Three phase inverter with a control loop then the system can be interfaced with three phase grid.

An LC filter is used to remove Harmonics so that the THD is less than 3% .

WAVEFORMS

The next stage after stepping up of panel voltage to a high DC voltage is converting the DC voltage to AC sinusoidal voltage in accordance with grid compatibility .

ADVANTAGES OF MICROINVERTER There is no high-voltage or high-current DC in a

solar power system using Micro inverters. So, it is much safer for the installer, user, and the property.

No more partial shading problems if a solar panel is partially shaded, it will not affect the performance of other panels.

Since each solar panel has its own inverter, a failure would mean that only one panel is not working;

One panel’s poor performance would not affect its neighbor’s production, but if there is a shaded panel in a system with a central inverter then it can alter the energy output of other panels;

Multiple orientations of panels are possible with micro-inverters while a central inverter usually requires its panels to all face in the same direction

Micro inverters, however, have their own set of challenges including the following:30% more costlier than central inverters .

While a Central Inverter is typically installed on a wall or on the ground out of direct sunlight, a Microinverter is typically attached to the solar panel on the roof top, which can be a very harsh environment.