27 research outputs found
Comparison between PI and PR current controllers in grid connected PV inverters
This paper presents a comparison between
Proportional Integral (PI) and Proportional Resonant (PR) current
controllers used in Grid Connected Photovoltaic (PV) Inverters. Both
simulation and experimental results will be presented. A 3kW Grid-
Connected PV Inverter was designed and constructed for this
research.peer-reviewe
Design of PR current control with selective harmonic compensators using Matlab
This paper presents a procedure to design a Proportional Resonant (PR) current
controller with additional PR selective harmonic compensators for Grid Connected
Photovoltaic (PV) Inverters. The design of the PR current control and the harmonic
compensators will be carried out using Matlab. Testing was carried out on a 3kW Grid-
Connected PV Inverter which was designed and constructed for this research. Both simulation
and experimental results will be presented.peer-reviewe
Single-phase microgrid with seamless transition capabilities between modes of operation
Microgrids are an effective way to increase the
penetration of DG into the grid. They are capable of operating
either in grid-connected or in islanded mode thereby increasing
the supply reliability for the end user. This paper focuses on
achieving seamless transitions from islanded to grid-connected
and vice versa for a single phase microgrid made up from
voltage controlled voltage source inverters (VC-VSIs) and current
controlled voltage source inverters (CC-VSIs) working together in
both modes of operation. The primary control structures for the
VC-VSIs and CC-VSIs is considered together with the secondary
control loops that are used to synchronize the microgrid as a
single unit to the grid. Simulation results are given that show
the seamless transitions between the two modes without any
disconnection times for the CC-VSIs and VC-VSIs connected
to the microgrid.peer-reviewe
Performance Comparison for Virtual Impedance Techniques Used in Droop Controlled Islanded Microgrids
Reactive power sharing and voltage harmonic distortion compensation of droop controlled single phase islanded microgrids
When paralleling multiple inverters that are capable
of operating as an island, the inverters typically employ the
droop control scheme. Traditional droop control enables the
decentralized regulation of the local voltage and frequency of
the microgrid by the inverters. The droop method also enables
the inverters to share the real and reactive power required by the
loads. This paper focuses on some of the limitations of parallel
islanded single phase inverters using droop control. Algorithms
with the aim to address the following limitations in islanded
operation were proposed: reactive power sharing and reduction
of the voltage harmonic distortion at the point of common
coupling (PCC). Experimental results were then presented to
show the suitability of the proposed algorithms in achieving
reactive power sharing and in improving the voltage harmonic
distortion at the PCC.peer-reviewe
Control of a doubly fed induction machine in a wind energy conversion system
This paper presents research done on the closed-loop control of the Doubly Fed Induction Machine (DFIM) applied to a Wind Energy Conversion System (WECS). Basic generator configurations used in wind energy systems, mainly fixed-speed and adjustable speed generators are discussed. A suitable Stator Flux Oriented (SFO) control topology for the DFIM is shown with which it is possible to control the stator active and reactive power. The control system designed was implemented on an experimental rig which emulates the behaviour of a practical WECS. A brief overview of sensorless algorithms is also presented; these algorithms are used to provide rotor speed/position estimates in the absence of a speed sensor. Practical results in both sensored and sensorless operation are shown including measurements for rotor currents, stator active/reactive power and rotor speed/position estimates.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe
Modeling of an EMC test-bench for conducted emissions in solid state applications
In the area of EMC performance of electric motor
drives, research is mainly focused on the EMC performance of
inverter based drives. However, in most instances the soft starter
is still an appropriate choice for motor control especially when
accurate speed control of the load is not a specific requirement.
The EMI generation of these converters has not been given the
required importance, with only a few publications regarding this
issue available in the last decades. A simulation model that
considers the operation of solid state devices in an EMC
conducted emission measurement laboratory environment was
developed. The model was implemented in MATLAB® and
Simulink® using a time domain approach. Models for the LISN,
EMI receiver, power cables, thyristor power modules and
induction motor load were developed and implemented. These
models were developed so as to reflect the actual physics of the
components and, where possible, model parameters were
obtained through analysis of the geometry of the system through
simplifications of the surrounding environment. The simulation
was then used to gain insight on the EMI generation
mechanisms of the solid state system.non peer-reviewe
Design of a high efficiency wide input range isolated Cuk Dc-Dc converter for grid connected regenerative active loads
The objective of this research is to build a regenerative active load unit with a very
wide input voltage range in order to support a wide variety of dc supply equipment such as dc
power supplies and batteries. These are usually tested by active or passive load units (resistive
loads) for long periods of time to detect early failures and reliability issues. The power drawn from
the devices under test are dissipated into heat by the resistive loads. The system being proposed in
this paper will consist of a grid connected inverter and an efficient wide input voltage range dc-dc
converter. This system will allow the energy drawn from the devices under test to be fed back to
the grid. The only energy consumed corresponds to the losses within the system.
The aim of the project is concerned with the construction of a 1kW regenerative active load unit.
The dc-dc converter, irrespective of the input voltage will feed power at a constant voltage of 200V
to the grid connected inverter. An input voltage ranging from 35V up to 400V will be supported by
the regenerative active load unit with a handling power of 1kW throughout the whole range.
This paper shall present the results obtained during the testing of the 1kW regenerative active load
unit.peer-reviewe