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POWER QUALITY IMPROVEMENT IN A PV

DISTRIBUTION SYSTEM BY USING D-STATCOM

Guide : Prof. S.SRIKANTH PROFESSOR

BY:P.S.V.SUBRAHMANYAMREGD No: 11221D4313

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ABSTRACT:

The main aim of this paper is the voltage regulation & power quality which is the most important operational requirements in power network at both transmission and distribution levels. Whenever there is a penetration of photovoltaic cell power to the low voltage distribution grid, there occur the problem of mismatch in voltage and frequency in the network, perhaps caused by non linear loads, generating harmonics. In this D-STATCOM is used to improve the voltage regulation thereby the power system stability.

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OBJECTIVES

To analyze the effect of non-linear loads on power system.

To study different methods already proposed for mitigation of harmonics due to non-linear loads.

To propose a Best way to mitigate the current harmonics and reactive power compensation.

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CONTENTS:

Introduction

Operation Of D-STATCOM

Proposed Topology

Photovoltaic Cell

Matlab modeling

References

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INTRODUCTION

In today’s scenario power quality maintenance in a power system is very essential because of the increase in different types of loads that pollute power systems.

The use of the power electronic devices in power distribution system gives rise to harmonics and reactive power disturbances.

o A voltage dip will occur, if the reactive power is consumed from the grid, this affects other sensitive loads which are connected to the grid.

Hence compensation is necessary for these types of

loads for requiring reactive power.

SOLUTIONS TO POWER QUALITY PROBLEMS

There are two approaches to the mitigation of power quality problems.

1. load conditioning 2. line-conditioning

Passive filters have been most commonly used to limit the flow of harmonic currents in distribution systems.

The performances of Conventional method (LC filter) is not satisfactory due to the drawbacks

Among the different new technical options available to improve power quality, D-STATCOM have proved to be an important and flexible alternative to compensate for current and voltage disturbances in power distribution systems.

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DISTRIBUTION NETWORK

Simple line presentation of generating distribution network

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DISTRIBUTION STATIC SYNCHRONOUS COMPENSATOR (D-STATCOM)

oD-STATCOM is the most important controller for distribution networks. It has been widely used to precisely regulate system voltage, improve voltage profile, reduce voltage harmonics, reduce transient voltage disturbances and load compensation.

oD-STATCOM uses a power-electronics converter to synthesize the reactive power output.

oA D-STATCOM converter is controlled using pulse width modulation (PWM) or other voltage/current-shaping techniques .

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D-STATCOM controllers can be constructed based on both voltage source inverter (VSI) topology and current source inverter (CSI) topology

In practice, CSI topology is not used for D-STATCOM. The reason for this is related to the higher losses on the DC reactor of CSI compared to the DC capacitor of VSI.

VSI-based topology has the advantage because an inductance of a coupling transformer Tr (if present) can constitute, partially or completely, the inductance of AC filter

The VSI converters for D-STATCOM are constructed based on multi-level topologies, with or without use of a transformer. These solutions provide support for operation with a high level of terminal voltage

General Topology

10General topology of VSI-based and CSI-based DSTATCOM

OPERATION OF D-STATCOM

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Configuration of D-STATCOM

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PHOTOVOLTAIC CELL: A PV system consists of a number of interconnected

components.

At present, photovoltaic (PV) generation is assuming increased importance as renewable energy Sources(RES) application because of advantages such as simplicity of allocation, high dependability, absence of fuel cost, low maintenance and lack of noise and wear due to the absence of moving parts.

There are two main system configurations

1. stand-alone PV system 2. stand-alone and grid-connected

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Schematic Diagram of Grid-Connected PV System

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STAND-ALONE AND GRID-CONNECTED SYSTEM

Schematic diagram of grid-connected photovoltaic system

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THREE-PHASE GRID-CONNECTED PHOTOVOLTAIC ENERGY CONVERSION SYSTEM:

Mathematical model for PV cell

Open circuit voltage

Light generated current

Reverse saturation current

Short circuit current

Irradiation

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MATLAB/SIMULINK MODEL OF PROPOSED GRID CONNECTED PV SYSTEM WITH OUT D-STATCOM

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SIMULATED OUTPUT WAVE FORMS OF SOURCE VOLTAGE, SOURCE CURRENT, LOAD CURRENT WITH OUT COMPENSATOR

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SIMULATION SHOWING NON UNITY POWER FACTOR WITH OUT D-STATCOM

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MATLAB/SIMULINK MODEL OF PROPOSED GRID CONNECTED PV SYSTEM WITH D-STATCOM

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SIMULATED OUTPUT WAVE FORMS OF SOURCE VOLTAGE, SOURCE CURRENT, LOAD CURRENT WITH COMPENSATOR

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SIMULATION SHOWING UNITY POWER FACTOR BY USING D-STATCOM

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CONCLUSION

In this paper we have modeled and analyzed the PV (photovoltaic) power system is being integrated with D-Statcom to low voltage power distribution grid at consumer end to compensate the harmonics coming from grid side inverter and other side we have different loads in that, most of the unbalanced nonlinear loads injects harmonic currents to source side and effects the source current. By using D-Statcom, the source current does not effect. In this, we have studied and analyzed the operation and performance of D-statcom at unbalanced non linear load condition and also gives the comparison by using with and without D-statcom. This proposed model is implemented using MATLAB SIMULINK software and the obtained resultant waveforms are evaluated and system stability effectiveness and power system performance have been established.

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REFERENCE: [1]. Furuhashi.T, S.Okuma, Y. Uchikawa, “a study on the theory of

instantaneous reactive power”, IEEE Trans. Industrial Electronics, , vol.37, No. 1, pp. 86-90, 1990.99

[2].Ghosh A., G..Ledwich, “Load compensating DSTATCOM in weak ACsystem”, IEEE Trans. Power Delivery, vol.18, No. 4, pp. 1302-1309,2003.

[3]. Hingorani NG, Gyugyi L. Understanding FACTS. Concepts and Technology of Flexible AC Transmision Systems. New York: IEEE Press, 19

[4]. H Akagi . Active Filters and Energy Storage Systems for Power Conditioning in Japan. Proc. of First International Conference on Power Electronics Systems and Application, 2004; 80–88.

[5]. J. Solanki and B. Singh , "A Comparison of Control Algorithms for dstatcom" ieee t ransactions on industrial elect ronics, VOL. 56, NO.7, mL Y 2009.

[6]. Ledwich.G , A.Ghosh,. “Power Quality Enhancement Using CustomPower Devices”, Kluwer Academic Publisher, 2002.

[7]. Papic I, Blazic B,. Improved D-STATCOM Control for Operation with UnbalancedCurrents and Voltages. IEEE Trans. Power Delivery, Vol. 21, No. 1, 2006; 225–233.

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Queries ?

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