One of the major problems observed in distributionsystems in recent days is Power Quality. Today most of the industries,commercial customers and residents are using the sophisticated electricalequipment based on semiconductor device, these equipment pollute the powerquality. Themost significant problems in the distribution system are the very high voltagedrop, especially at residential usage. This exaggerated voltage drop affectsthe performance of electric stoves and heaters that the customers are forced towait for a long time to make stew, to toast bread, and to boil water. Moreover,the working life of light bulbs, in addition to giving less-bright lights, isgetting shortened life due to under voltages. It is also a lot of times thatlight bulbs and electronic appliances get burned due to over voltages, which isa symptom of weak voltage regulation of the distribution system power system.Negligence of the effects of voltage and current distortions from both theutility side and end-user side is another motivating factor.
Even thoughutilization of semiconductor based equipments are greatly increasing from dayto day, without giving emphasis to the issue of harmonic distortions. The lossof electric power at moderate to heavy rain, and following lightning strokes;the increasing number of distribution transformers with high oil leakage;hanging overhead lines and resulting short circuits are also some of the majorobservations that lead to questionable electric power quality of the utility. Mostindustrial companies are installing capacitor bank, but it will not functional becauseof the improper rating and fuse failure due to disturbances in the system.
Tosolve this problem, custom power devices are used. One of those devicesUPQC, which isthe most efficient and effective modern custom power device used in powerdistribution networks, because the main purpose ofUPQC is to compensate for the supply voltage PQ issues such as voltage sags,swells, unbalance, flicker, harmonics, and load current PQ problems such asharmonics, unbalance, reactive current, power factor to unity and neutralcurrent.Theinvestigation of power quality issues and enhancement of power quality issuesusing UPQC in distribution system provides alternative method of mitigatingpower quality phenomena where power quality is a core issue. The studytherefore sought to address the following questions:1. What design parameters that must be considered in the systemwith respect to the size and type of filters, DC link capacitors, etc?2. What simulation techniques to utilize in order to effectivelymodel the UPQC?3. What control algorithms are suit for the UPQC?4.
What evaluation method to be used to measure theeffectiveness of the system?