International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017
p-ISSN: 2395-0072
www.irjet.net
POWER ANGLE CONTROL SCHEME FOR INTEGRATION OF UPQC IN GRID CONNECTED PV SYSTEM Akkela Krishnaveni 1, Addagatla Nagaraju 2. 1 2
Lecturer in Electrical Engineering, Dr. B.R. Ambedkar GMR Polytechnic, for Women, Karimnagar, Telangana, India
Lecturer in Electrical Engineering, Government Polytechnic, Station Ghanpur, Warangal, Telangana, India
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Abstract - The quality of electric power is greatly affected
by the proliferation of non-linear loads in electrical energy processing applications like switched mode power supplies, electric motor drives, battery chargers, etc., The custom power devices like UPQC has gained more importance in power quality arena as it gives the best solution for all power quality issues. UPQC is the combination of both shunt and series active power filters connected through a common DC link capacitor. The shunt active power filter is the most corrective measure to remove the current related problems, power factor improvement by supplying reactive power and regulates DC link voltage. The series APF acts as controlled voltage source and corrects voltage related problems, like sag or swell, flickering, harmonics, etc.,. As a combination of both of these, UPQC improves service reliability. In the present work, shunt inverter control is based on modified active- reactive (p-q) power theory, uses High selectivity filter (HSF) for reference current generation. The series APF uses Power Angle Control (PAC) scheme for compensating sag/swell, interruption and voltage related problems along with sharing a part of load reactive power demand with shunt APF and thus ease its loading and makes the utilization of UPQC to be optimal. The topology uses three phase three leg inverters for both shunt APF and series APF. The gating signals were generated using Hysteresis controller. The output of High step-Up DC-DC Converter is used to work as DC voltage source for both APFs. The input voltage for the converter is provided by Photo Voltaic array incorporated with P&O MPPT technique. The use of high step-up DC-DC converter is for high voltage gain with better efficiency. The present topology avoids the PLL in shunt active power filter. The simulation results are presented to show the effectiveness of the three phase, three-wire PV-UPQC and here obtained an acceptable THD for source current and kept load voltage at its nominal value. Key Words: Unified Power Quality Conditioner (UPQC) High selectivity filter (HSF) Voltage Source Inverter(VSI) INTRODUCTION: The term power quality got significant importance in the electric power industry. The increasing application of electronic equipment and distributed generation has led to the degradation of power quality by injecting harmonics, flicker and voltage imbalance into the system. In addition, switching of capacitor banks, lightning strikes on transmission lines and various faults on the network also Š 2017, IRJET
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creates the power quality issues such as transients, voltage sag or swell, interruptions, etc.,.. The equipment which is increasingly susceptible to the variations in Power Quality is termed as Sensitive Equipment or Sensitive Load [4]. For proper load operation, it requires pure sinusoidal voltage. With fast growing digital technology, the devices that depending upon volatile memory chip for storages are increasing and these are potentially at risk from power quality events. To achieve this pure sinusoidal voltage and to meet the power quality standards, it is necessary to use some compensation techniques. Previously passive filters using tuned LC components have been used to mitigate the harmonics, which are low in cost, simple in configuration. But this has drawbacks of fixed compensation, bulky in size and creates resonance problems. Hence a modern solution is found in the form of active power filtering. The shunt APF is suitable for suppressing source current harmonics and the series APF is suitable to compensate source voltage imperfections. The power electronic controllers used in distribution system for the purpose of supplying a level of reliability or power quality, which is essentially required by sensitive load, is termed as custom power devices [4]. These devices have the ability to perform voltage regulation and current interruption functions within the distribution system and hence it can be treated as power conditioning device. UPQC is one of those efficient custom power devices which is the combination of both shunt and series active power filters connected through a common DC link capacitor [1], [2], [6]. The shunt active power filter is the most corrective measure to remove the current related problems, power factor improvement by supplying reactive power and regulates DC link voltage [6]. The series APF acts as controlled voltage source [6] and corrects voltage related problems such as sag/swell, flickering, harmonics etc.,. As a combination of both of these, UPQC improves service reliability. In the present work a modified p-q theory is used for reference current generation shunt APF. It uses two high selectivity filters (HSF) [15], [16], which are used to obtain the fundamental components from current and voltage signals in �-� reference frame. The fixed power angle control
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