Paladugula V Aditya

Tella Nagaraju

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International Journal of Advanced Technology in Engineering and Science              www.ijates.com  
Volume No.02, Issue No. 12, December  2014                                            ISSN (online): 2348 – 7550 
231 | P a g e  
APPLICATION OF ANN LOGIC CONTROLLER FOR 
IMPROVEMENT OF POWER QUALITY USING UPQC 
 
Paladugula V Aditya
1
, Tella Nagaraju
2
 
1
P.G.Student, Dept. of EEE, Sree Vahini Institute of Science & Technology, Tiruvuru, A.P, (India) 
2
Asst. Prof, Dept. of EEE, Sree Vahini Institute of Science & Technology, Tiruvuru, A.P, (India) 
 
 
ABSTRACT 
This project report emphasis enhancement of power quality by using UPQC with ANN logic controller (FLC), 
and with the conventional proportional-integral (PI) controller. The unified power quality conditioner (UPQC) 
is being used as a universal active power conditioning device to mitigate both current and voltage harmonics at 
a distribution side of power system network. The proposed ANN logic controllers (FLC) are capable of 
providing good static and dynamic performances compared to PID controller 
 
I. INTRODUCTION 
 
Power Quality (PQ) has become an important issue since many loads at various distribution ends like adjustable 
speed drives, process industries, printers, domestic utilities; computers, microprocessor based equipment etc. 
have become intolerant to voltage fluctuations, harmonic content and interruptions. Power Quality (PQ) mainly 
deals with issues like maintaining a fixed voltage at the Point of Common Coupling (PCC) for various 
distribution voltage levels irrespective of voltage fluctuations, maintaining near unity power factor power drawn 
from the supply, blocking of voltage and current unbalance from passing upwards from various distribution 
levels, reduction of voltage and current harmonics in the system and suppression of excessive supply neutral 
current. Conventionally, passive LC filters and fixed compensating devices with some degree of variation like 
thyristor switched capacitors, thyristor switched reactors were employed to improve the power factor of ac 
loads. Such devices have the demerits of fixed compensation, large size, ageing and resonance. Nowadays 
equipment using power semiconductor devices, generally known as active power filters (APF's), Active Power 
Line Conditioners (APLC's) etc. are used for the power quality issues due to their dynamic and adjustable 
solutions. Flexible AC Transmission Systems (FACTS) and Custom Power products like STATCOM (STATic 
synchronous Compensator), DVR (Dynamic Voltage Restorer), etc. deal with the issues related to power quality 
using similar control strategies and concepts. Basically, they are different only in the location in a power system 
where they are deployed and the objectives for which they are deployed. In this paper, various extraction 
algorithms for generating reference signals and various modulation techniques for generating pulses already 
developed and published are discussed. Criterion for selection of dc link capacitor and interfacing filter design 
are also discussed. 
 
II. UNIFIED POWER FLOW CONTROLLER 
 
Basic block diagram of UPQC is shown in Fig 1. The voltage at PCC may be or may not be distorted depending 
on the other non-linear loads connected at PCC. Here we assume the voltage at PCC is distorted. Two voltage 
source inverters are connected back to back, sharing a common dc link. One inverter is connected parallel with 
International Journal of Advanced Technology in Engineering and Science              www.ijates.com  
Volume No.02, Issue No. 12, December  2014                                            ISSN (online): 2348 – 7550 
232 | P a g e  
the load. It acts as shunt APF, helps in compensating load harmonic current as well as to maintain dc link 
voltage at constant level. The second inverter is connected in series with utility voltage by using series 
transformers and helps in maintaining the load voltage sinusoidal. 
 
Fig 1 Basic Block Diagram of UPQC 
The major disadvantage of p-q theory is that it gives poor results under distorted and/or unbalanced input/utility 
voltages. In order to eliminate these limitations, the reference load voltage signals extracted for series APF are 
used instead of actual load voltages. 
For phase a, the load voltage and current in α-β coordinates can be represented by π/2 lead as 
                                   
                                      
Considering phase a, the phase-a instantaneous load active and instantaneous load reactive powers can be 
represented by  
          .            
Where    La = La + La , La = La + La      
       
III. CONTROLING TECHNIQUES FOR UPQC 
 
3.1 PI Controller 
A PI Controller (proportional-integral controller) is a special case of the PID controller in which the derivative 
(D) of the error is not used. 
The controller output is given by 
 
The lack of derivative action may make the system more steady in the steady state in the case of noisy data. This 
is because derivative action is more sensitive to higher-frequency terms in the inputs. Without derivative action, 
a PI-controlled system is less responsive to real (non-noise) and relatively fast alterations in state and so the 
system will be slower to reach set point and slower to respond to perturbations. 
 
International Journal of Advanced Technology in Engineering and Science              www.ijates.com  
Volume No.02, Issue No. 12, December  2014                                            ISSN (online): 2348 – 7550 
233 | P a g e  
3.2 Artificial Neural Networks 
Artificial Neural Networks are relatively crude electronic models based on the neural structure of the brain. The 
brain basically learns from experience. It is natural proof that are beyond the scope of current computers are 
indeed solvable by small energy efficient packages. This brain modeling also promises a less technical way to 
develop machine solutions. Now, advance in biological research promise an initial understanding of the natural 
thinking mechanism. This research shows that brain stores information, as patterns. Some of these patterns are 
very complicated and allow us the ability to recognize individual faces from any different angles. This process 
of storing information as patterns, utilizing those patterns, and then solving problems encompasses a new field 
in computing. A one-layer network with R input elements and S neurons follow. In this network, each element 
of the input vector p is connected to each neuron input through the weight matrix W. The ith neuron has a 
summer that gathers its weighted inputs and bias to form its own scalar output n(i). The various n(i) taken 
together form an S-element net input vector n. 
 
Fig 4 Single Layer Neural Network 
IV. SIMULATION RESULTS 
 
To verify the operating performance of the proposed UPQC, a 3-phase electrical system is simulated using 
MATLAB software. 
 
Fig 5 Matlab/Simulink Model 
International Journal of Advanced Technology in Engineering and Science              www.ijates.com  
Volume No.02, Issue No. 12, December  2014                                            ISSN (online): 2348 – 7550 
234 | P a g e  
 
Fig 6 Matlab/Simulink Source and Load Voltages with PI Controller 
 
 
 
 
 
 
Table 1 (THD’s) Of UPQC with Different Controllers 
V. CONCLUSION 
 
Custom power devices like DVR, D-STATCOM, and UPQC can enhance power quality in the distribution 
system. Based on the power quality problem at the load or at the distribution system, there is a choice to choose 
particular custom power device with specific compensation. Unified Power Quality Conditioner (UPQC) is the 
combination of series and shunt APF, which compensates supply voltage and load current imperfections in the 
distribution system. The UPQC considered in this project is a multifunction power conditioner which can be 
used to compensate for various voltage disturbance of the power supply, to correct any voltage fluctuation and 
to prevent the harmonic load current from entering the power system. A simple control technique based on unit 
vector templates generation is proposed for UPQC. Proposed model has been simulated in MATLAB. The 
simulation results show that the input voltage harmonics and current harmonics caused by non-linear load can 
be compensated effectively by the proposed control strategy. The closed loop control schemes of direct current 
control, for the proposed  UPQC have been described. A suitable mathematical model of the UPQC has been 
developed with different shunt controllers (PI & ANN) and simulated results have been described which 
establishes the fact that in both the cases the compensation is done but the response of ANN controller is faster 
and the THD is minimum for the both the voltage and current which is evident from the plots and comparison 
table 1. 
 
REFERENCES 
 
[1] B.Singh, K. Al-Haddad, and A. Chandra. “A review of active power filters for power quality 
improvement. “IEEE Trans. Ind. Electron., vol.45. no.5.pp. 960-971, Oct.1999. 
[2] C.A. Quinn and N.Mohan. “Active filtering of harmonic currents in three-phase, four-wire systems with 
three-phase and single-phase nonlinear loads” in proc. 7th IEEE APEC,1992. Pp. 829-836. 
Control techniques Total harmonic 
distortion (THD %) 
Pi controller 12.41% 
ANN controller 5.84% 
International Journal of Advanced Technology in Engineering and Science              www.ijates.com  
Volume No.02, Issue No. 12, December  2014                                            ISSN (online): 2348 – 7550 
235 | P a g e  
[3] H. Akagi, Y. Kanazawa and A.Nabae, “Instantaneous reactive power compensators comprising switching 
devices without energy storage components.” IEEE Trans. Ind. Appl., vol. 1A-20, no. 3. Pp. 625-630. 
May/jun. 1984. 
[4] Y.Komatsu and T.Kawabata.“A control method of active power filter in unsymmetrical and distorted 
voltage system”, in Proc. Conf. IEEE Power Converters., 1997. Vol. 1, pp. 161-168. 
[5] M.T.Haque, “Single-phase PQ theory.” In Proc. 33rd IEEE PESC,2002, vol.4, pp. 1815-1820. 
[6] J.M. Correa, S.Chakraborty, M. G. Simoes, and F.A.Farrent, “A single phase high frequency AC 
microgrid with an unified power quality conditioner”,in Conf. Rec. 38th IEEE Ias Annu. Meeting, 2003, 
vol. 2, pp. 956-962. 
[7] V.Khadkikar, A. Chandra, A.O. Barry, and T.D. Nguyen, “Application of UPQC to protect a sensitive load 
on a polluted distribution network.” In Proc. IEEE PES General Meeting, Montreal, QC, Canada, 2006. 6 
pp. 
[8] V.Khadkikar, A. Chandra, A.O. Barry, and T.D. Nguyen, “Conceptual analysis of unified power quality 
conditioner (UPQC).”, in Proc. IEEE ISTE, 2006, pp 1088-1093. 
[9] M.Aredes, K.Heumann, and E.H.Watanabe, “An universal active power line conditioner”, IEEE Trans. 
Power Del., vol.13, no. 2, pp. 545-551, Arl.1998. 
[10] R. Faranda and I. Valade, “UPQC compensation strategy and design aimed at reducing losses, “ in Proc. 
IEEE ISIE, 2002, vol. 4, pp. 1264-1270. 
 
PALADUGULA V ADITYA received his Bachelor of technology from EEE- SREE RAMA 
INSTITUTE OF TECHNOLOGY & SCIENCE (JNTUH, Kakinada). He is currently 
pursuing Masters in SREE VAHINI INSTITUTE OF SCIENCE & TECHNOLOGY 
(JNTUK) in the department of Power Systems. 
 
 
TELLA NAGARAJU working as Asst. Prof at SREE VAHINI INSTITUTE OF SCIENCE 
& TECHNOLOGY. He received his Masters from ADAM'S ENGINEERING COLLEGE, 
JNTUH. He has 2 years working experience in teaching. He guided several UG & PG 
projects. His areas of interests power systems, power electronics & Electrical Machines. 
 
 


APPLICATION OF ANN LOGIC CONTROLLER FOR IMPROVEMENT OF POWER QUALITY USING UPQC

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APPLICATION OF ANN LOGIC CONTROLLER FOR IMPROVEMENT OF POWER QUALITY USING UPQC

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