DIPLOMA THESIS
CHRISTOS LOUKAS
«THEORETICAL STUDY AND CONSTRUCTION OF A SINGLE PHASE
INVERTER FOR THE INTERCONNECTION OF A WIND TURBINE TO
THE LOW VOLTAGE GRID»
SUPERVISORS :
EMMANUEL TATAKIS, DR.-ING. PROFESSOR, DIRECTOR OF LEMEC
CHAROULA ZOGOGIANNI , PHD CANDIDATE, UNIVERSITY OF PATRAS
THE UNDER STUDY SYSTEM
1. Wind Turbine
2. P.M.S.G.
3. Three phase Rectifier (AC/DC)
4. Interleaved Boost (DC/DC)
5. DC BUS
6. Full Bridge Single Phase Inverter with MOSFET (DC/AC)
7. LC Filter
8. Transformer
9. Power Grid 230V/50Hz
CONTROL OF THE
INVERTER
CONTROL OF THE INVERTER
CONTROL OF ACTIVE AND REACTIVE POWER INJECTED TO THE GRID
1. Direct Control of Active and Reactive Power
V V
P  1 2 sin 
X
V12 V1 V2
Q

sin 
X
X
CONTROL OF THE INVERTER
CONTROL OF ACTIVE AND REACTIVE POWER INJECTED TO THE GRID
2. Control of Active and Reactive Power in d-q Axis
•Quick response
•Zero Steady State Error
•Usage of PLL
CONTROL OF THE INVERTER
3. Proportional Resonant Controller- PR
 PR ( s )  K p  K I 
C  s
s 2  2  C  s   2
SIMULATIONS
SIMULATION FOR THE CONNECTION TO THE GRID
WITH CONSTANT DC INPUT
DIRECT CONTROL OF ACTIVE AND REACTIVE POWER
Active Power injected to the grid
Reactive Power injected to the grid
CONTROL OF ACTIVE AND REACTIVE POWER IN D-Q
AXIS
Active Power injected to the grid
Reactive Power injected to the grid
PR CONTROLLER
Active Power injected to the grid
Reactive Power injected to the grid
CURRENT INJECTED TO THE GRID IN EACH CONTROL
Current injected to the grid in Direct Active
and Reactive Power Control
Current injected to the grid in Active and
Reactive Power Control in d-q axis
Current injected to the grid in PR
Controller
HARMONICS
Is the Grid
IDEAL??
CONTROL IN GRID WITH HARMONICS-CURENT
WAVEFORMS
Direct Active-Reactive Control
PR Controller
Active-Reactive control in d-q axis
PR CONTROLLER WITH SELECTIVE HARMONIC
COMPENSATOR
H HC ( s) 

3,5,7...
K Ih 
c  s
s 2  2  c  s  (  h)2
PR CONTROLLER WITH SELECTIVE HARMONIC
COMPENSATOR
Current injected to the grid
FFT analysis of current injected to the grid
CONTROL OF THE DC BUS
Active Power injected to the grid (black)
DC Voltage
Reactive Power
Current injected to the grid
PLL
1.Single Phase PLL with virtual signals
2.Second Order Generalized Integrator (SOGI) PLL
PLL
Basic Harmonic of the grid(green), signal
in the input of PLL (blue)
Frequency output of the PLL
Output of the PLL (green) compared
with basic harmonic of the grid (blue)
Vd, Vq, V0 components
CONSTRUCTION
CONTROL OF THE PULSATION OF THE INVERTER
Digital Control of the pulsation with the
Microcontroller dsPIC30F4011
Inputs:
•Grid Voltage
•Pulse by the Zero-Crossing Detector
• Current Injected to the grid
•Signals by 2 trimmers
Outputs:
• 4 Signals for the control of the MOSFETs of the Inverter
CONSTRUCTION OF THE CONVERTER
BOARD OF THE INVERTER
Inverter-Top View
Inverter-Side View
CONSTUCTION OF THE CONVERTER
BOARDS OF THE MICROCONTROLLER, POWER SUPPLIES, TRANSDUCERS
Microcontroller
Power Supplies
Voltage and Current Transducers
EXPERIMENTS
EXPERIMENTS ON A RESISTIVE LOAD
Voltage (blue) & Output Current (yellow)
Power (red)
Experimental Setup
Input (W)
Output (W)
Power Rating
With transformer
234
203,3
86,8%
500
442,2
88,4%
800
673,32
84,2%
Input (W)
Output (W)
Power Rating
Without transformer
60
56,4
94%
198
186,52
94,2%
240
233,68
97,3%
345,6
339,11
98,1%
Dead Time
EXPERIMENT RESULTS
CONNECTION TO THE GRID- TESTS BEFORE THE CONNECTION
Pulse from the zero-crossing detector (blue), grid
voltage (yellow)
Grid Voltage (purple), Inverter Voltage (blue), Invert
Current (yellow), Power (red)
Pulse from the zero-crossing detector (blue), grid voltage
(yellow)-Zoom in
EXPERIMENT RESULTS
CONNECTION TO THE GRID- OPEN LOOP
Current injected to the grid (yellow) for Active Power of 280W
530W
430W
FFT analysis of the grid injected current for Active
Power of 430 W
EXPERIMENTAL RESULTS
CONNECTION TO THE GRID- OPEN LOOP –INJECTION OF HARMONICS
Sinusoidal of 50 Hz
Sinusoidal of Higher Harmonics (150, 250 Hz)
Voltage of the inverter (blue), Voltage of
the grid (purple), Current on a resistive
load (yellow)- Before the connection
530W
EXPERIMENTAL RESULTS
CONNECTION TO THE GRID- OPEN LOOP –INJECTION OF HARMONICS
Current injected to the grid (yellow) for Active Power of 230W
445W
400W
EXPERIMENTAL RESULTS
COMPARISON OF THE RESULTS WITH AND WITHOUT HARMONICS INJECTION
Without Harmonic Injection for 280W
Without Harmonic Injection for 380W
With Harmonic Injection for 230W
Without Harmonic Injection for 400W
Thank you for listening!!!