Seminar Ppt

A Cost-effective Three-phase Grid-connected Inverter with Maximum Power Point Tracking

CONTENTS  INTRODUCTION  MULTILEVEL INVERTERS  THREE-PHASE BOOST-TYPE GRID-CONNECTED

INVERTER CIRCUIT  CONTROL PRINCIPLE OF MPPT  EXPERIMENTAL VERIFICATION  APPLICATIONS  CONCLUSION  REFERENCE

INTRODUCTION  Because

of global environmental concerns and increasing energy demands, more attention is being concentrated on the renewable energy technologies.

 Compared

to the traditional energy resources, the PV system, which converts sunlight into electric power, releases no pollutants for environmental concern.

 These

types of sources supply dc power while the present power grid accepts 60Hz ac power

A

solar cell is the basic building block of a PV system. A typical cell produces 0.5 to 1V of electricity. Solar cells are combined together to become modules or if large enough, known as an array.. ig.1. cell to array model

MULTILEVEL INVERTERS

ig.2. Cascade H-bridge Multilevel inverter

THREE-PHASE BOOST-TYPE GRID-CONNECTED INVERTER

Fig.3. Power Stage of the boost type inverter With PV Array Connection.

 In

Region-1 (0~60º), Va>0, Vc>0 and Vb<0. Additionally, their differential voltages are:

Fig.4. Six Region In A Line Cycle

Stage-1 Stage-

Stage-2

Stage-3

Fig.5. Three stages for different switching patterns

OCC-one cycle controller  It

has a single power stage.

A

low value dc side inductor and its input dc

voltage can vary over a wide range.

 These

key features of OCC are all desirable for

low cost high efficiency PV power generation.

OCC-one cycle controller

Fig. 6. Diagram Of The OCC Core For The Boost Type Inverter

Control principle of MPPT a

cost-effective MPPT method integrated within the OCC controller.

It features the following advantages:  i) A single power stage: MPPT and dc-to-ac power conversion can be achieved within a single power stage.  ii)

Simple control circuit: only the PV output voltage is sensed and used to achieve MPPT.

 iii)

Good MPPT capability with acceptable precision: well tracks the real MPP.

Control principle of MPPT For a generic PV array that is comprised of M modules in parallel and N cells in series in each module, the output power is:

Where, ILG -- light-generated current of each module; Ios

-- reverse saturation current of each module; q -- Electronic charge; Rgs -- series resistance; A

-- Ideality factor; K -- Boltzmann’s constant; C

OCC Controller With MPPT Function

Fig.7 OCC Controller With MPPT Function



Fig.8 Simulation Result For Pg and Pin Versus Vg

EXPERIMENTAL VERIFICATION  Model  Peak

type: Shell SP75;

power: 75W

 Short

circuit current: 4.8A;

 Open

circuit voltage: 21.7V;

 CLK1

and CLK2 frequency: fs = 40 kHz;

 DC

side capacitor: C = 3mF;

 DC

side inductor L = 0.6mH;

 kg

= 0.0675; Rs = 0.332Ω; k = 0.0096;

Fig.9 The Extracted Power Pg The Maximum Pmax And Relative Error vs. Time.

Fig.10 Input Of The Inverter

Fig.11 Output Of The Inverter:

APPLICATION  City

Residential homes

 Industrial Applications  Central Power Stations  Commercial

buildings

Fig.12 GRID CONNECTED SOLAR SYSTEM

CONCLUSION  By

using this proposed system we can effectively use the solar energy to meet a part of the day to day energy demand.





The control method is simple . The proposed circuit requires only one power stage to achieve the MPPT function and dc-to-ac power conversion.

 Data

shows that the proposed method has good MPPT capability and high quality output performance

REFERENCE  G.K. Andersen, C. Klumpner, S.B. Kjaer, F. Blaabjerg, “A new green power inverter for fuel cells”.

 C. Qiao, K.M. Smedley, “Three-phase gridconnected inverters interface for alternative energy sources with unified constant-frequency integration control”.  G.R. Walker, P.C. Sernia, “Cascaded DC-DC converter connection of photovoltaic modules”.  F. Antunes, A.M. Torres, “A three-phase gridconnected PV system”.