International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017
p-ISSN: 2395-0072
www.irjet.net
A Review on Unified Power Quality Conditioner for 3P4W System Abhishek Singh1, A K Jhala2, Manish Prajapati3 1PG
Scholar, RKDF College of Engineering, Bhopal, M.P., India Professor, RKDF College of Engineering, Bhopal, M.P., India 3Assistant Professor, RKDF College of Engineering, Bhopal, M.P., India ---------------------------------------------------------------------***--------------------------------------------------------------------2Associate
Abstract – Power Quality is the hot issue in the power
world. Due to continuous use of the non-linear loads the voltage and current waveform shows the distortions. This distorted waveform produces quality issues in the distribution system. Power quality (PQ) mainly deals with issues like maintain a fixed voltage at the point of common coupling (PCC) for various distributed voltage levels irrespectively of voltage fluctuation, blocking of voltage and current unbalance from various distribution levels. In this paper discuss the various type of harmonics generated due to presence of the non linear loads. Also discuss the literature behind the Unified Quality Conditioner (UPQC) for three phase four wire system (3P4W). Key Words: Power Quality, PCC, PCC, UPQC, 3P4W, etc,…
1. INTRODUCTION With the advent of power semiconductor switching devices, like thyristors, GTO's (Gate Turn off thyristors), IGBT's (Insulated Gate Bipolar Transistors) and many more devices, control of electric power has become a reality. Such power electronic controllers are widely used to feed electric power to electrical loads, such as adjustable speed drives (ASD's), furnaces, computer power supplies, HVDC systems etc. The power electronic devices due to their inherent non-linearity draw harmonic and reactive power from the supply. In three phase systems, they could also cause unbalance and draw excessive neutral currents. The injected harmonics, reactive power burden, unbalance, and excessive neutral currents cause low system efficiency and poor power factor. In addition to this, the power system is subjected to various transients like voltage sags, swells, flickers etc. These transients would affect the voltage at distribution levels. Excessive reactive power of loads would increase the generating capacity of generating stations and increase the transmission losses in lines. Hence supply of reactive power at the load ends becomes essential. 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 equipments etc. have become intolerant to voltage fluctuations, harmonic content and interruptions. Power Quality (PQ) mainly deals with issues © 2017, IRJET
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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 equipments 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. Active Power Filters can be classified, based on converter type, topology and the number of phases. Converter types are Current Source Inverter (CSI) with inductive energy storage or Voltage Source Inverter (VSI) with capacitive energy storage. The topology can be shunt, series or combination of both. The third classification is based on the number of phases, such as single phase systems, three phase systems or three phase four wire systems. The UPQC is now a day’s more popular for reduction in voltage and current issue in power quality. In this paper discuss the literature regarding to the different approach utilize in reduction of harmonics in the UPQC
2. HARMONICS IN POWER SYSTEM Many of researchers are work together for reducing the harmonics in the power grid. Due to growing use of nonlinear loads and devices harmonics are generated. This harmonic produce distorted voltage in the supply system. So it reduces power quality. AhChoy Liew [1] analyzed excessive neutral currents in 3P4W fluorescent lighting due ISO 9001:2008 Certified Journal
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