Seminar Ppt

A Cost-effective Three-phase Grid-connected

Inverter with Maximum Power Point Tracking

CONTENTSCONTENTS INTRODUCTION

MULTILEVEL INVERTERS

THREE-PHASE BOOST-TYPE GRID-CONNECTED

INVERTER CIRCUIT

CONTROL PRINCIPLE OF MPPT

EXPERIMENTAL VERIFICATION

APPLICATIONS

CONCLUSION

REFERENCE

INTRODUCTIONINTRODUCTION 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..

Fig.1. cell to array model

Fig.2. Cascade H-bridge Multilevel inverter

MULTILEVEL INVERTERS

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-Stage-1

Stage-2Stage-2

Stage-3Stage-3

Fig.5. Three stages for different switching patterns

OCC-one cycle controllerOCC-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.

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

OCC-one cycle controllerOCC-one cycle controller

ControlControl principleprinciple of MPPTof 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.

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;T -- Temperature in oC.

ControlControl principleprinciple of MPPTof MPPT

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 type: Shell SP75;

Peak 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:

APPLICATIONAPPLICATIONCity Residential homes

Industrial Applications

Central Power Stations

Commercial buildings

Fig.12 GRID CONNECTED SOLAR SYSTEM

CONCLUSIONCONCLUSION

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

REFERENCEREFERENCE 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 grid-connected 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 grid-connected PV system”.