ABSTRACT:
Voltage sag is literally one of power quality
problem and it become severe to industrial customers. Voltage sag can cause
miss operation to several sensitive electronic equipments. That problem can be
mitigating with voltage injection method using custom power device, Dynamic
Voltage Restorer (DVR). This paper presents modeling and analysis of a DVR with
pulse width modulation (PWM) based controller using Matlab/Simulink. The
performance of the DVR depends on the efficiency of the control technique
involved in switching the inverter. This paper proposed two control techniques
which is PI Controller (PI) and Fuzzy Logic Controller (FL). Comprehensive results
are presented to assess the performance of each controller as the best power
quality solution. Other factors that also can affect the performance and
capability of DVR are presented as well.
KEYWORDS:
1.
Voltage sag
2.
Dynamic Voltage Restore
3.
Pulse Width Modulation (PWM)
4.
PI Controller
5.
Fuzzy Logic Controller
SOFTWARE: MATLAB/SIMULINK
Figure1.
DVR Modelling using Matlab/Simulink
Figure
2. (a) Injection voltage from DVR controlled by PI ; (b) injection
voltage
controlled by FL
Figure
3. (a) Output voltage at load 1 after injection voltage from DVR controlled by
PI; (b) Output voltage at load 1after injection voltage controlled by FL.
Figure
4. (a) Injection voltage from DVR controlled by PI; (b) injection voltage
controlled by FL.
Figure
5. (a) Output voltage at load 1 after injection voltage from DVR controlled by
PI; (b) Output voltage at load 1after injection voltage controlled by FL.
Figure
6. THD generated when PI controller is applied
Figure
7. THD generated when FL controller is applied.
CONCLUSION:
In
this study, the modeling and simulation of DVR controlled by PI and FL
Controller has been developed using Matlab/Simulink. For both controller, the
simulation result shows that the DVR compensates the sag quickly (70μs) and provides
excellent voltage regulation. DVR handles all types, balanced and unbalanced
fault without any difficulties and injects the appropriate voltage component to
correct any fault situation occurred in the supply voltage to keep the load voltage
balanced and constant at the nominal value. Both controllers show an excellent
performance and generate low THD (<5%). However, it can be seen that FL
Controller gives better performance with THD generated with only 0.64% whilst
PI generated 1.68% THD. However, other several factors that can affect the
performance of DVR need to be addressed for enhancement of the output voltage.
These factors are the energy storage capacity and transformer rating. From the
simulation, it clearly shows the importance of these two factors and how they
affect the performance of DVR. Therefore, when it comes to implementation, it
is crucial to consider these factors, so that the performance of DVR is optimized.
REFERENCES:
[1]
Omar, R. Rahim, N.A. “New Control Technique Applied in Dynamic Voltage Restorer
for Voltage Sag Mitigation” Industrial Electronics and Applications, 2009.
ICIEA 2009. 4th IEEE Conference on.
[2]
Faisal, M.F. “Power Quality Management Program: TNB’s Experience”, Distribution
Engineering, TNB 2005.
[3]
Wahab, S.W. Yusof, A.M. “Voltage Sag Mitigation Using Dynamic Voltage Restorer
(DVR) System, ELEKTRIKA, 8(2),2006, 32-37.
[4]
IEEE Standard Board (1995), “IEEE Std. 1159-1995”, IEEE Recommended Practice for Monitoring Electric
Power Quality”. IEEE Inc. New York.
[5]
Kim H. “Minimal Energy Control for a Dynamic Voltage Restorer”, In proceedings
of the Power Conversion Conference, Osaka, Japan, 2002, pp. 428-433.
