CONTENT 1 1. INTRODUCTION 4. SIMULATION RESULTS 2. CONDITIONER TOPOLOGIES 3. SRF - BASED ALGORITHM 5. CONCLUSIONS

2 I. INTRODUCTION Harmonic pollution of the power supply system has risen significantly in recent years due primarily to an increase of non- linear loads Industrial customersResidential and commercial

3 I. INTRODUCTION -Power supply voltages become distorted due to the high level of undesired harmonic current drawn from the utility Voltage sags or swells -Voltage sags or swells, voltage unbalances and voltage harmonics have helped to decrease the power quality needed for critical loads.

4 To solve or minimize some power quality problems, Unified Power Quality Conditioners (UPQC) and Active Power Filters (APF) have been developed I. INTRODUCTION

5 - APFs are normally used to compensate utility voltage disturbances such as sags, swells, unbalances and harmonic voltages I. INTRODUCTION Power Filtered Harmonics - Shunt APFs have commonly been used to suppress the harmonic currents of the nonlinear loads

6 Fig. 1. Conditioner Topologies: UPQC and Line-interactive UPS system. II. CONDITIONER TOPOLOGIES Power Supply static switch series PWM converter Parallel PWM convert er DC- Link Load

7 II. CONDITIONER TOPOLOGIES -The series PWM converter must behave as a current source with a high enough impedance to isolate the line from the load harmonic currents. -The parallel PWM converter must behave as a voltage source with a high enough admittance to absorb the harmonic currents of the load - When the UPS system is implemented, an additional static switch ( sw ) is used to provide the disconnection between the UPS system and the power supply.

8 III. SRF - BASED ALGORITHM - The SRF-based algorithms can be used to perform load unbalance compensation or to independently compensate each of the three phases. When the load unbalance compensation is implemented the source currents become balanced and sinusoidal - However, when the phases are individually controlled the source currents will be sinusoidal but unbalanced