Download LV GRID VOLTAGE REGULATION USING TRANSFORMER

LV GRID VOLTAGE REGULATION
USING TRANSFORMER ELECTRONIC
TAP CHANGING, WITH PV INVERTER
REACTIVE POWER INJECTION
ABSTRACT
Despite increasing levels of solar-PV penetration in electrical distribution networks, to date the
inverters of these PV systems have not been significantly utilized for distribution network control.
One particular area of interest for these inverters is their potential to inject/absorb reactive power
to/from grid to help manage the voltage profile of their distribution feeder. Various reactive power
management strategies have been proposed to address this issue using different voltage-reactive
power relationships, but their effectiveness can be limited by competing performance objectives, or
simply because the higher resistance characteristics of a typical LV feeder constrain the range of
voltage regulation that can be achieved by reactive power injection.
This project addresses this issue by proposing a combined strategy, where an electronic tap-changer is
incorporated into the feeder distribution transformer to provide the feeder voltage regulation function,
and the PV DG systems at each feeder bus are then used to minimize feeder losses by providing local
load reactive power support. The investigation takes into account a variety of issues such as feeder
impedance, dynamic transformer tap changing, different load types and levels of PV penetration.
EXISTING SYSTEM
I t is becoming increasingly recognized that as penetration levels of PV generation into the electrical
grid increase, the consequential reverse power flow that occurs along the LV and MV feeders can
cause significant over-voltage problems along these feeders [1]. Various centralized and distributed
control strategies have been proposed to address these voltage rise problems by varying the reactive
power injected by the PV inverters themselves. However, centralized control strategies generally need
a significant investment in sensors and communication systems, while localized distributed control
strategies typically require relatively complex control concepts within the PV inverters to ensure that
the DG systems continue to work effectively without adverse interactions. Feeder loss reduction is
also another factor that is commonly taken into account when considering how best to regulate
reactive power injection at a local Distributed Generation.
PROPOSED SYSTEM
The integrated voltage regulation strategy proposed in this paper is to incorporate an electronic tap
changer into the primary distribution transformer of the feeder, and use its functionality as the
primary voltage control mechanism. The reactive power injection of the PV inverters at each bus is
then locally controlled to supply the load reactive power at that bus, within the overall kVA rating
capability of the inverter as shown. This control strategy approximately minimises the VA power flow
along the feeder, and hence substantially reduces the feeder power losses. Note of course that the
reactive power capacity of PV inverters is limited by their kVA rating. But if slightly overrated
inverters are installed,
TOOLS AND SOFTWARE USED:
 MP LAB
 ORCAD/PSPICE
 MATLAB/SIMULINK
OUTPUT:
 HARDWARE
 SIMULATION