CONTENT
1. INTRODUCTION
2. CONDITIONER TOPOLOGIES
3. SRF - BASED ALGORITHM
4. SIMULATION RESULTS
5. CONCLUSIONS
1
I. INTRODUCTION
Harmonic pollution of the power supply system has risen
significantly in recent years due primarily to an increase of nonlinear loads
Residential and commercial
Industrial customers
2
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 unbalances and voltage
harmonics have helped to decrease the power quality needed
for critical loads.
Voltage sags
or swells
3
I. INTRODUCTION
To solve or minimize some power quality problems, Unified
Power Quality Conditioners (UPQC) and Active Power Filters
(APF) have been developed
4
I. INTRODUCTION
- APFs are normally used to compensate utility voltage
disturbances such as sags, swells, unbalances and harmonic
voltages
- Shunt APFs have commonly been used to suppress the
harmonic currents of the nonlinear loads
Harmonics
Power Filtered
5
II. CONDITIONER TOPOLOGIES
static
switch
DCLink
Load
Power
Supply
series
PWM
converter
Parallel
PWM
convert
er
Fig. 1. Conditioner Topologies: UPQC and Line-interactive UPS system. 6
II. CONDITIONER TOPOLOGIES
- 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.
- 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
7
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
8